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PART 1 VARIABLE SPEED DRIVE IN PUMPING STATIONS ADVANTAGESPART 2 SPEED CONTROL IN INDUCTION MOTORS
2
Variable Speed Drive in Pumping StationsADVANTAGES1
PART 1
3
Variable Speed Drive in Pumping StationsADVANTAGES
1 Introduction
2 Criteria for the selection of the Variable Speed Drives
3 Energy saving in pumps and fans with Variable Speed Drives
31 Typical pump and fan curves32 Movement of the pump curve in accordance
with the speed drop33 Movement of the power and efficiency curves
in accordance with the speed drop34 Basic relationships for the power control35 Efficiency of pumps with VSD
4 Methods for flow control
5 Needed information for a correct consulting in the energy saving field
SUMMARY ndash PART 1
4
Variable Speed Drives in Pumping StationsINTRODUCTION1
5
11 Power ElectronicsPower Electronics offers to its clients optimization options for the production process through the application of variable speed drives and softstarters in a wide variety of industrial fields
Variable Speed Drive in Pumping StationsADVANTAGES
1 INTRODUCTION
2 As a result of the application of variable speed drives and softstarters a spectacular raise of the quality of the product and an absolute improvement of the mechanical and electrical maintenance of the Company
6
Variable Speed Drives in Pumping StationsCRITERIA FOR THE SELECTION OF A VARIABLE SPEED DRIVE
2
7
Variable Speed Drive in Pumping StationsADVANTAGES
A Input Filters
B Input Chokes
C Protection Degree
D Ambient Temperature
E Constant and Variable Torque VSD
F VSD Applications
G Technical Assistance
2 CRITERIA FOR THE SELECTION OF A VARIABLE SPEED DRIVE
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
8
WHAT IS ELECTROMAGNETIC COMPATIBILITY
It is a concept linked to any electronic device
This concept means the ability of a device to avoid the generation of interferences above a defined dB level
It means the measure of its immunity versus a defined dB level
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
9
WHAT PHENOMENA PRODUCE THE RADIOFREQUENCIES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
10
RFI EMISSION SOURCES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo The RFI can be radiated and conduced raquo The conduction can be produced through the Motor Cables through the Power Supply Cables and through the Earth Connections
11
CABLE LENGTH
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Vcc = Ve 141 = 380 141 = 534= 500 141 = 720= 690 141 = 9729 raquo 40 meters of screened cable
raquo 150 meters of screened cable
12
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 90A ndash 170A
13
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 210A ndash 2200A
14
PROTECTION DEGREE FOR EXTRA PROTECTION
C PROTECTION DEGREE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo IP54 protection impedes that dust or any other particles damage the devices
raquo In this case splashing occurred near the motor donrsquot damage our products
15
OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Operation current at 45ordm
Over-heating Characteristics for SD700 Series
0
25
50
75
100
125
150
175
200
0 25 50 75 400Hz
Dri
ve C
urr
ent
()
Overload peak 1 sec
Overload 30 sec at 50ordm
Operation current at 40ordm
Operation current at 45ordm
Operation current at 50ordm
Overload peak for 1 sec
Overload for 30 sec at 50ordm
Operation current at 40ordm
Operation current at 50ordm
Overload for 60 sec at 40ordm
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
2
Variable Speed Drive in Pumping StationsADVANTAGES1
PART 1
3
Variable Speed Drive in Pumping StationsADVANTAGES
1 Introduction
2 Criteria for the selection of the Variable Speed Drives
3 Energy saving in pumps and fans with Variable Speed Drives
31 Typical pump and fan curves32 Movement of the pump curve in accordance
with the speed drop33 Movement of the power and efficiency curves
in accordance with the speed drop34 Basic relationships for the power control35 Efficiency of pumps with VSD
4 Methods for flow control
5 Needed information for a correct consulting in the energy saving field
SUMMARY ndash PART 1
4
Variable Speed Drives in Pumping StationsINTRODUCTION1
5
11 Power ElectronicsPower Electronics offers to its clients optimization options for the production process through the application of variable speed drives and softstarters in a wide variety of industrial fields
Variable Speed Drive in Pumping StationsADVANTAGES
1 INTRODUCTION
2 As a result of the application of variable speed drives and softstarters a spectacular raise of the quality of the product and an absolute improvement of the mechanical and electrical maintenance of the Company
6
Variable Speed Drives in Pumping StationsCRITERIA FOR THE SELECTION OF A VARIABLE SPEED DRIVE
2
7
Variable Speed Drive in Pumping StationsADVANTAGES
A Input Filters
B Input Chokes
C Protection Degree
D Ambient Temperature
E Constant and Variable Torque VSD
F VSD Applications
G Technical Assistance
2 CRITERIA FOR THE SELECTION OF A VARIABLE SPEED DRIVE
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8
WHAT IS ELECTROMAGNETIC COMPATIBILITY
It is a concept linked to any electronic device
This concept means the ability of a device to avoid the generation of interferences above a defined dB level
It means the measure of its immunity versus a defined dB level
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
9
WHAT PHENOMENA PRODUCE THE RADIOFREQUENCIES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
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10
RFI EMISSION SOURCES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo The RFI can be radiated and conduced raquo The conduction can be produced through the Motor Cables through the Power Supply Cables and through the Earth Connections
11
CABLE LENGTH
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
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Vcc = Ve 141 = 380 141 = 534= 500 141 = 720= 690 141 = 9729 raquo 40 meters of screened cable
raquo 150 meters of screened cable
12
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
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raquo Power electronics for SD700 series 90A ndash 170A
13
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 210A ndash 2200A
14
PROTECTION DEGREE FOR EXTRA PROTECTION
C PROTECTION DEGREE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo IP54 protection impedes that dust or any other particles damage the devices
raquo In this case splashing occurred near the motor donrsquot damage our products
15
OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
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Operation current at 45ordm
Over-heating Characteristics for SD700 Series
0
25
50
75
100
125
150
175
200
0 25 50 75 400Hz
Dri
ve C
urr
ent
()
Overload peak 1 sec
Overload 30 sec at 50ordm
Operation current at 40ordm
Operation current at 45ordm
Operation current at 50ordm
Overload peak for 1 sec
Overload for 30 sec at 50ordm
Operation current at 40ordm
Operation current at 50ordm
Overload for 60 sec at 40ordm
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
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28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
3
Variable Speed Drive in Pumping StationsADVANTAGES
1 Introduction
2 Criteria for the selection of the Variable Speed Drives
3 Energy saving in pumps and fans with Variable Speed Drives
31 Typical pump and fan curves32 Movement of the pump curve in accordance
with the speed drop33 Movement of the power and efficiency curves
in accordance with the speed drop34 Basic relationships for the power control35 Efficiency of pumps with VSD
4 Methods for flow control
5 Needed information for a correct consulting in the energy saving field
SUMMARY ndash PART 1
4
Variable Speed Drives in Pumping StationsINTRODUCTION1
5
11 Power ElectronicsPower Electronics offers to its clients optimization options for the production process through the application of variable speed drives and softstarters in a wide variety of industrial fields
Variable Speed Drive in Pumping StationsADVANTAGES
1 INTRODUCTION
2 As a result of the application of variable speed drives and softstarters a spectacular raise of the quality of the product and an absolute improvement of the mechanical and electrical maintenance of the Company
6
Variable Speed Drives in Pumping StationsCRITERIA FOR THE SELECTION OF A VARIABLE SPEED DRIVE
2
7
Variable Speed Drive in Pumping StationsADVANTAGES
A Input Filters
B Input Chokes
C Protection Degree
D Ambient Temperature
E Constant and Variable Torque VSD
F VSD Applications
G Technical Assistance
2 CRITERIA FOR THE SELECTION OF A VARIABLE SPEED DRIVE
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8
WHAT IS ELECTROMAGNETIC COMPATIBILITY
It is a concept linked to any electronic device
This concept means the ability of a device to avoid the generation of interferences above a defined dB level
It means the measure of its immunity versus a defined dB level
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
9
WHAT PHENOMENA PRODUCE THE RADIOFREQUENCIES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
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10
RFI EMISSION SOURCES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
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raquo The RFI can be radiated and conduced raquo The conduction can be produced through the Motor Cables through the Power Supply Cables and through the Earth Connections
11
CABLE LENGTH
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
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Vcc = Ve 141 = 380 141 = 534= 500 141 = 720= 690 141 = 9729 raquo 40 meters of screened cable
raquo 150 meters of screened cable
12
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
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raquo Power electronics for SD700 series 90A ndash 170A
13
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 210A ndash 2200A
14
PROTECTION DEGREE FOR EXTRA PROTECTION
C PROTECTION DEGREE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo IP54 protection impedes that dust or any other particles damage the devices
raquo In this case splashing occurred near the motor donrsquot damage our products
15
OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
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Operation current at 45ordm
Over-heating Characteristics for SD700 Series
0
25
50
75
100
125
150
175
200
0 25 50 75 400Hz
Dri
ve C
urr
ent
()
Overload peak 1 sec
Overload 30 sec at 50ordm
Operation current at 40ordm
Operation current at 45ordm
Operation current at 50ordm
Overload peak for 1 sec
Overload for 30 sec at 50ordm
Operation current at 40ordm
Operation current at 50ordm
Overload for 60 sec at 40ordm
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
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ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
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CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
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28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
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29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
4
Variable Speed Drives in Pumping StationsINTRODUCTION1
5
11 Power ElectronicsPower Electronics offers to its clients optimization options for the production process through the application of variable speed drives and softstarters in a wide variety of industrial fields
Variable Speed Drive in Pumping StationsADVANTAGES
1 INTRODUCTION
2 As a result of the application of variable speed drives and softstarters a spectacular raise of the quality of the product and an absolute improvement of the mechanical and electrical maintenance of the Company
6
Variable Speed Drives in Pumping StationsCRITERIA FOR THE SELECTION OF A VARIABLE SPEED DRIVE
2
7
Variable Speed Drive in Pumping StationsADVANTAGES
A Input Filters
B Input Chokes
C Protection Degree
D Ambient Temperature
E Constant and Variable Torque VSD
F VSD Applications
G Technical Assistance
2 CRITERIA FOR THE SELECTION OF A VARIABLE SPEED DRIVE
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
8
WHAT IS ELECTROMAGNETIC COMPATIBILITY
It is a concept linked to any electronic device
This concept means the ability of a device to avoid the generation of interferences above a defined dB level
It means the measure of its immunity versus a defined dB level
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
9
WHAT PHENOMENA PRODUCE THE RADIOFREQUENCIES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
10
RFI EMISSION SOURCES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo The RFI can be radiated and conduced raquo The conduction can be produced through the Motor Cables through the Power Supply Cables and through the Earth Connections
11
CABLE LENGTH
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Vcc = Ve 141 = 380 141 = 534= 500 141 = 720= 690 141 = 9729 raquo 40 meters of screened cable
raquo 150 meters of screened cable
12
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 90A ndash 170A
13
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 210A ndash 2200A
14
PROTECTION DEGREE FOR EXTRA PROTECTION
C PROTECTION DEGREE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo IP54 protection impedes that dust or any other particles damage the devices
raquo In this case splashing occurred near the motor donrsquot damage our products
15
OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Operation current at 45ordm
Over-heating Characteristics for SD700 Series
0
25
50
75
100
125
150
175
200
0 25 50 75 400Hz
Dri
ve C
urr
ent
()
Overload peak 1 sec
Overload 30 sec at 50ordm
Operation current at 40ordm
Operation current at 45ordm
Operation current at 50ordm
Overload peak for 1 sec
Overload for 30 sec at 50ordm
Operation current at 40ordm
Operation current at 50ordm
Overload for 60 sec at 40ordm
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
5
11 Power ElectronicsPower Electronics offers to its clients optimization options for the production process through the application of variable speed drives and softstarters in a wide variety of industrial fields
Variable Speed Drive in Pumping StationsADVANTAGES
1 INTRODUCTION
2 As a result of the application of variable speed drives and softstarters a spectacular raise of the quality of the product and an absolute improvement of the mechanical and electrical maintenance of the Company
6
Variable Speed Drives in Pumping StationsCRITERIA FOR THE SELECTION OF A VARIABLE SPEED DRIVE
2
7
Variable Speed Drive in Pumping StationsADVANTAGES
A Input Filters
B Input Chokes
C Protection Degree
D Ambient Temperature
E Constant and Variable Torque VSD
F VSD Applications
G Technical Assistance
2 CRITERIA FOR THE SELECTION OF A VARIABLE SPEED DRIVE
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
8
WHAT IS ELECTROMAGNETIC COMPATIBILITY
It is a concept linked to any electronic device
This concept means the ability of a device to avoid the generation of interferences above a defined dB level
It means the measure of its immunity versus a defined dB level
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
9
WHAT PHENOMENA PRODUCE THE RADIOFREQUENCIES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
10
RFI EMISSION SOURCES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo The RFI can be radiated and conduced raquo The conduction can be produced through the Motor Cables through the Power Supply Cables and through the Earth Connections
11
CABLE LENGTH
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Vcc = Ve 141 = 380 141 = 534= 500 141 = 720= 690 141 = 9729 raquo 40 meters of screened cable
raquo 150 meters of screened cable
12
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 90A ndash 170A
13
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 210A ndash 2200A
14
PROTECTION DEGREE FOR EXTRA PROTECTION
C PROTECTION DEGREE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo IP54 protection impedes that dust or any other particles damage the devices
raquo In this case splashing occurred near the motor donrsquot damage our products
15
OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Operation current at 45ordm
Over-heating Characteristics for SD700 Series
0
25
50
75
100
125
150
175
200
0 25 50 75 400Hz
Dri
ve C
urr
ent
()
Overload peak 1 sec
Overload 30 sec at 50ordm
Operation current at 40ordm
Operation current at 45ordm
Operation current at 50ordm
Overload peak for 1 sec
Overload for 30 sec at 50ordm
Operation current at 40ordm
Operation current at 50ordm
Overload for 60 sec at 40ordm
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
6
Variable Speed Drives in Pumping StationsCRITERIA FOR THE SELECTION OF A VARIABLE SPEED DRIVE
2
7
Variable Speed Drive in Pumping StationsADVANTAGES
A Input Filters
B Input Chokes
C Protection Degree
D Ambient Temperature
E Constant and Variable Torque VSD
F VSD Applications
G Technical Assistance
2 CRITERIA FOR THE SELECTION OF A VARIABLE SPEED DRIVE
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
8
WHAT IS ELECTROMAGNETIC COMPATIBILITY
It is a concept linked to any electronic device
This concept means the ability of a device to avoid the generation of interferences above a defined dB level
It means the measure of its immunity versus a defined dB level
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
9
WHAT PHENOMENA PRODUCE THE RADIOFREQUENCIES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
10
RFI EMISSION SOURCES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo The RFI can be radiated and conduced raquo The conduction can be produced through the Motor Cables through the Power Supply Cables and through the Earth Connections
11
CABLE LENGTH
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Vcc = Ve 141 = 380 141 = 534= 500 141 = 720= 690 141 = 9729 raquo 40 meters of screened cable
raquo 150 meters of screened cable
12
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 90A ndash 170A
13
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 210A ndash 2200A
14
PROTECTION DEGREE FOR EXTRA PROTECTION
C PROTECTION DEGREE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo IP54 protection impedes that dust or any other particles damage the devices
raquo In this case splashing occurred near the motor donrsquot damage our products
15
OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Operation current at 45ordm
Over-heating Characteristics for SD700 Series
0
25
50
75
100
125
150
175
200
0 25 50 75 400Hz
Dri
ve C
urr
ent
()
Overload peak 1 sec
Overload 30 sec at 50ordm
Operation current at 40ordm
Operation current at 45ordm
Operation current at 50ordm
Overload peak for 1 sec
Overload for 30 sec at 50ordm
Operation current at 40ordm
Operation current at 50ordm
Overload for 60 sec at 40ordm
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
7
Variable Speed Drive in Pumping StationsADVANTAGES
A Input Filters
B Input Chokes
C Protection Degree
D Ambient Temperature
E Constant and Variable Torque VSD
F VSD Applications
G Technical Assistance
2 CRITERIA FOR THE SELECTION OF A VARIABLE SPEED DRIVE
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
8
WHAT IS ELECTROMAGNETIC COMPATIBILITY
It is a concept linked to any electronic device
This concept means the ability of a device to avoid the generation of interferences above a defined dB level
It means the measure of its immunity versus a defined dB level
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
9
WHAT PHENOMENA PRODUCE THE RADIOFREQUENCIES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
10
RFI EMISSION SOURCES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo The RFI can be radiated and conduced raquo The conduction can be produced through the Motor Cables through the Power Supply Cables and through the Earth Connections
11
CABLE LENGTH
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Vcc = Ve 141 = 380 141 = 534= 500 141 = 720= 690 141 = 9729 raquo 40 meters of screened cable
raquo 150 meters of screened cable
12
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 90A ndash 170A
13
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 210A ndash 2200A
14
PROTECTION DEGREE FOR EXTRA PROTECTION
C PROTECTION DEGREE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo IP54 protection impedes that dust or any other particles damage the devices
raquo In this case splashing occurred near the motor donrsquot damage our products
15
OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Operation current at 45ordm
Over-heating Characteristics for SD700 Series
0
25
50
75
100
125
150
175
200
0 25 50 75 400Hz
Dri
ve C
urr
ent
()
Overload peak 1 sec
Overload 30 sec at 50ordm
Operation current at 40ordm
Operation current at 45ordm
Operation current at 50ordm
Overload peak for 1 sec
Overload for 30 sec at 50ordm
Operation current at 40ordm
Operation current at 50ordm
Overload for 60 sec at 40ordm
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
8
WHAT IS ELECTROMAGNETIC COMPATIBILITY
It is a concept linked to any electronic device
This concept means the ability of a device to avoid the generation of interferences above a defined dB level
It means the measure of its immunity versus a defined dB level
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
9
WHAT PHENOMENA PRODUCE THE RADIOFREQUENCIES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
10
RFI EMISSION SOURCES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo The RFI can be radiated and conduced raquo The conduction can be produced through the Motor Cables through the Power Supply Cables and through the Earth Connections
11
CABLE LENGTH
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Vcc = Ve 141 = 380 141 = 534= 500 141 = 720= 690 141 = 9729 raquo 40 meters of screened cable
raquo 150 meters of screened cable
12
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 90A ndash 170A
13
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 210A ndash 2200A
14
PROTECTION DEGREE FOR EXTRA PROTECTION
C PROTECTION DEGREE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo IP54 protection impedes that dust or any other particles damage the devices
raquo In this case splashing occurred near the motor donrsquot damage our products
15
OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Operation current at 45ordm
Over-heating Characteristics for SD700 Series
0
25
50
75
100
125
150
175
200
0 25 50 75 400Hz
Dri
ve C
urr
ent
()
Overload peak 1 sec
Overload 30 sec at 50ordm
Operation current at 40ordm
Operation current at 45ordm
Operation current at 50ordm
Overload peak for 1 sec
Overload for 30 sec at 50ordm
Operation current at 40ordm
Operation current at 50ordm
Overload for 60 sec at 40ordm
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
9
WHAT PHENOMENA PRODUCE THE RADIOFREQUENCIES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
10
RFI EMISSION SOURCES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo The RFI can be radiated and conduced raquo The conduction can be produced through the Motor Cables through the Power Supply Cables and through the Earth Connections
11
CABLE LENGTH
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Vcc = Ve 141 = 380 141 = 534= 500 141 = 720= 690 141 = 9729 raquo 40 meters of screened cable
raquo 150 meters of screened cable
12
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 90A ndash 170A
13
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 210A ndash 2200A
14
PROTECTION DEGREE FOR EXTRA PROTECTION
C PROTECTION DEGREE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo IP54 protection impedes that dust or any other particles damage the devices
raquo In this case splashing occurred near the motor donrsquot damage our products
15
OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Operation current at 45ordm
Over-heating Characteristics for SD700 Series
0
25
50
75
100
125
150
175
200
0 25 50 75 400Hz
Dri
ve C
urr
ent
()
Overload peak 1 sec
Overload 30 sec at 50ordm
Operation current at 40ordm
Operation current at 45ordm
Operation current at 50ordm
Overload peak for 1 sec
Overload for 30 sec at 50ordm
Operation current at 40ordm
Operation current at 50ordm
Overload for 60 sec at 40ordm
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
10
RFI EMISSION SOURCES IN A VSD
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo The RFI can be radiated and conduced raquo The conduction can be produced through the Motor Cables through the Power Supply Cables and through the Earth Connections
11
CABLE LENGTH
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Vcc = Ve 141 = 380 141 = 534= 500 141 = 720= 690 141 = 9729 raquo 40 meters of screened cable
raquo 150 meters of screened cable
12
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 90A ndash 170A
13
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 210A ndash 2200A
14
PROTECTION DEGREE FOR EXTRA PROTECTION
C PROTECTION DEGREE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo IP54 protection impedes that dust or any other particles damage the devices
raquo In this case splashing occurred near the motor donrsquot damage our products
15
OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Operation current at 45ordm
Over-heating Characteristics for SD700 Series
0
25
50
75
100
125
150
175
200
0 25 50 75 400Hz
Dri
ve C
urr
ent
()
Overload peak 1 sec
Overload 30 sec at 50ordm
Operation current at 40ordm
Operation current at 45ordm
Operation current at 50ordm
Overload peak for 1 sec
Overload for 30 sec at 50ordm
Operation current at 40ordm
Operation current at 50ordm
Overload for 60 sec at 40ordm
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
11
CABLE LENGTH
A INPUT FILTERS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Vcc = Ve 141 = 380 141 = 534= 500 141 = 720= 690 141 = 9729 raquo 40 meters of screened cable
raquo 150 meters of screened cable
12
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 90A ndash 170A
13
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 210A ndash 2200A
14
PROTECTION DEGREE FOR EXTRA PROTECTION
C PROTECTION DEGREE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo IP54 protection impedes that dust or any other particles damage the devices
raquo In this case splashing occurred near the motor donrsquot damage our products
15
OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Operation current at 45ordm
Over-heating Characteristics for SD700 Series
0
25
50
75
100
125
150
175
200
0 25 50 75 400Hz
Dri
ve C
urr
ent
()
Overload peak 1 sec
Overload 30 sec at 50ordm
Operation current at 40ordm
Operation current at 45ordm
Operation current at 50ordm
Overload peak for 1 sec
Overload for 30 sec at 50ordm
Operation current at 40ordm
Operation current at 50ordm
Overload for 60 sec at 40ordm
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
12
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 90A ndash 170A
13
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 210A ndash 2200A
14
PROTECTION DEGREE FOR EXTRA PROTECTION
C PROTECTION DEGREE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo IP54 protection impedes that dust or any other particles damage the devices
raquo In this case splashing occurred near the motor donrsquot damage our products
15
OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Operation current at 45ordm
Over-heating Characteristics for SD700 Series
0
25
50
75
100
125
150
175
200
0 25 50 75 400Hz
Dri
ve C
urr
ent
()
Overload peak 1 sec
Overload 30 sec at 50ordm
Operation current at 40ordm
Operation current at 45ordm
Operation current at 50ordm
Overload peak for 1 sec
Overload for 30 sec at 50ordm
Operation current at 40ordm
Operation current at 50ordm
Overload for 60 sec at 40ordm
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
13
USE OF INPUT CHOKES FOR HARMONIC REDUCTION
B INPUT CHOKES
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo Power electronics for SD700 series 210A ndash 2200A
14
PROTECTION DEGREE FOR EXTRA PROTECTION
C PROTECTION DEGREE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo IP54 protection impedes that dust or any other particles damage the devices
raquo In this case splashing occurred near the motor donrsquot damage our products
15
OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Operation current at 45ordm
Over-heating Characteristics for SD700 Series
0
25
50
75
100
125
150
175
200
0 25 50 75 400Hz
Dri
ve C
urr
ent
()
Overload peak 1 sec
Overload 30 sec at 50ordm
Operation current at 40ordm
Operation current at 45ordm
Operation current at 50ordm
Overload peak for 1 sec
Overload for 30 sec at 50ordm
Operation current at 40ordm
Operation current at 50ordm
Overload for 60 sec at 40ordm
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
14
PROTECTION DEGREE FOR EXTRA PROTECTION
C PROTECTION DEGREE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
raquo IP54 protection impedes that dust or any other particles damage the devices
raquo In this case splashing occurred near the motor donrsquot damage our products
15
OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Operation current at 45ordm
Over-heating Characteristics for SD700 Series
0
25
50
75
100
125
150
175
200
0 25 50 75 400Hz
Dri
ve C
urr
ent
()
Overload peak 1 sec
Overload 30 sec at 50ordm
Operation current at 40ordm
Operation current at 45ordm
Operation current at 50ordm
Overload peak for 1 sec
Overload for 30 sec at 50ordm
Operation current at 40ordm
Operation current at 50ordm
Overload for 60 sec at 40ordm
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
15
OVER-HEATING CHARACTERISTICS OF THE SD700 SERIES
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
Operation current at 45ordm
Over-heating Characteristics for SD700 Series
0
25
50
75
100
125
150
175
200
0 25 50 75 400Hz
Dri
ve C
urr
ent
()
Overload peak 1 sec
Overload 30 sec at 50ordm
Operation current at 40ordm
Operation current at 45ordm
Operation current at 50ordm
Overload peak for 1 sec
Overload for 30 sec at 50ordm
Operation current at 40ordm
Operation current at 50ordm
Overload for 60 sec at 40ordm
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
16
D AMBIENT TEMPERATURE
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
ENVIRONMENTAL TEMPERATURE
Power ElectronicsPower Electronics Variable Speed Drives are prepared to resist the hardest environmental working conditions
They CAN RESIST TILL 50ordmC 50ordmC AMBIENT TEMPERATURE WITHOUT OVER-SIZING THE VARIABLE SPEED DRIVE
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
17
raquo Competitors
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (40ordmC)
OVERLOAD 11In (40ordmC)
Temperature 60ordmC
THERMAL SHOT (85ordmC)
15 kw
11 kw
CONSTANT TORQUE
VARIABLE TORQUE
OVERLOAD 15In (50ordmC)
OVERLOAD 125 In (40ordmC)
Temperature 60ordmC
Temperature 70ordmC
Temperature 80ordmC
raquo Power ElectronicsPower Electronics
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
18
Variable Speed Drive in Pumping StationsADVANTAGES
E CONSTANT TORQUE AND VARIABLE TORQUE
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
POWER AT CONSTANT
TORQUE
POWER AT VARIABLE TORQUE
PVP
MODEL A 11 15 100MODEL B 15 185 115
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
19
F VARIABLE SPEED DRIVE APPLICATIONS
Variable Speed Drive in Pumping StationsADVANTAGES
[ BACK TO THE CRITERIA ][ BACK TO THE CRITERIA ]
CONTROL
The Variable Speed Drives extend the regulation field with regard toFlow fluctuationPressure controlTemperature controlLevel controlhellip
APPLICATIONS
Several applications can be consideredPumping stationsPressure groupsIrrigation systemsHigh concentration of carbonic monoxide oxygenhellipHeating and Air conditioninghellip
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
20
Variable Speed Drives in Pumping StationsENERGY SAVING IN PUMPS AND FANS3
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
21
31 TYPICAL PUMPS AND FANS CURVES
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
HEI
GH
T P
OW
ER A
ND
EFF
ICIE
NC
Y
H (m)
FLOW
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
22
32 MOVEMENT OF THE PUMP CURVE IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
H
16
14
12
10
8
6
4
2
20 40 60 80 100 120 140
nnom
08 n nom
07 n nom
09 n nom
Q (ls)
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
23
33 MOVEMENT OF THE POWER AND EFFICIENCY CURVES IN ACCORDANCE WITH THE SPEED DROP
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
p
Q
Power
Efficiency
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
24
34 BASIC RELATIONSHIPS FOR THE POWER CONTROL
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
POWER (W) = r x g x H x Q x ŋ-1
r = Density (Kgmsup3)
g = Gravity (981mssup2)
H = Height (m)
Q = Flow (msup3s)
ŋ = Efficiency
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
25
35 EFFICIENCY OF PUMPS WITH VARIABLE SPEED DRIVE
3 ENERGY SAVING IN PUMPS AND FANS WITH VSD
Variable Speed Drive in Pumping StationsADVANTAGES
50 6070
8085
80
88
8785
87
301 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
80
70
60
50
40
30
20
10
0
N = 1480 RPM
Efficiency curves
Curves H ndash Q
System curves
10 20 30 40Q flowm3min
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
26
Variable Speed Drives in Pumping StationsMETHODS FOR FLOW CONTROL4
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
27
Variable Speed Drive in Pumping StationsADVANTAGES
A Valve Control
B By ndash Pass Control
C Start ndash Stop Control (On Off)
D Variable Speed Drive
4 METHODS FOR FLOW CONTROL
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
[ SHOW ][ SHOW ]
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
28
A VALVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo Pumps always work at maximum speed
raquo The transversal section of the conduct or pipe
raquo Pressure increases when pipe cross section is reduced
raquo Problems with the over-heating of the fluids
raquo Cavitation turbulences
[ BACK TO THE LIST ][ BACK TO THE LIST ]
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
29
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s70
60
50
40
30
20
10
0
Height in m H2O
n = 1480 RPM
Efficiency curvesH-Q curves
System curves
10 20 30 40 Q Flow m3min100 Flow50 Flow
1009080706050
80 FLOW1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
30
A VALVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
QFLOW
BOTTLENECK INCREASES
1
Q
HEI
GH
T
H
OPERATIONAL POINT WITHOUT BOTTLENECK
7
POW
ER
KW
23
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
31
B BY - PASS CONTROL
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo This is the least efficient method with regard to the energy consumption
raquo The pump always works at maximum power without taking into account the flow level
Q
FLOW
BY-PASS EFFECT
Q
HEI
GH
T
H
OPERATIONAL POINT
WITHOUT BY-PASS
POW
ER
KW
System curves
Pump H ndash Q curves
Efficiency curves
[ BACK TO THE LIST ][ BACK TO THE LIST ]
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
32
C START ndash STOP CONTROL (On Off) CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It is recommendable for those systems in which the pumping flow is constant
raquo It leads to mechanical and electrical stress
raquo It does not allow to maintain constant parameters a small or big variation always exists
raquo Over-pressure during the starting
raquo Water hammering during the stop
[ BACK TO THE LIST ][ BACK TO THE LIST ]
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
33
D VARIABLE SPEED DRIVE CONTROL CHARACTERISTICS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
raquo It allows to keep constant those parameters to be controlled
raquoIt provides a reduction of absorbed power by the motor
raquo Compensation of reactive power of the motor
raquo Reduction of mechanical and electrical failures
raquo Reduction of civil construction cost in pumping systems
[ BACK TO THE LIST ][ BACK TO THE LIST ]
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
34
D VARIABLE SPEED DRIVE CONTROL GRAPHIC
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
STA
TIC
hei
ght 2
0 m
eter
s
Height in m H2O
n = 1480 RPM
Efficiency curves
H ndash P curves
System curves
10 20 30 40Q Flowm3min
70
60
50
40
30
20
10
0
80
490 kPa
637 kPa
REFERENCE
1 X n
09 X n
08 X n
07 X n
06 X n
05 X n
04 X n 1400RPM
PID
0
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
35
D VARIABLE SPEED DRIVE CONTROL TABLE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
SPEED DROP
9
8
Q
HEI
GH
T
H
OPERATIONAL POINT AT FULL LOAD
7
9
8
Q
FLOW
POW
ER
KW
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
36
D VARIABLE SPEED DRIVE CONTROL ENERGY MISUSE
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
POWER LOSSESH
EIG
HT
VALVES SYSTEM
FREQUENCY CONVERTER
REDUCED SPEED
MISUSED POWER
USEFUL POWERSTATIC
HEIGHT
SET POINT
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
37
D VARIABLE SPEED DRIVE CONTROL COMPARATIVE CURVES AND POWER REQUIREMENTS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
FLOW ()
POWER()
A Control using Variable Speed Drive
B Control using valve adjusting
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
38
D VARIABLE SPEED DRIVE IN WELLS
4 METHODS FOR FLOW CONTROL
Variable Speed Drive in Pumping StationsADVANTAGES
WINTERSUMMER
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
39
Variable Speed Drives in Pumping StationsNEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
5
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
40
ANALYSIS OF EXISTING SYSTEMSA Type of controlB Height curves and flow of the system
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
PUMP OR FAN DATAA Pump and fans efficiency curvesB Fan or pump powerC Motor curves
PROCESS INFORMATIONA Fluid or gas densityB Flows and required duty cyclesC Static and dynamic height values
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
41
IF WE DO NOT HAVE COMPLETE INFORMATION THE FOLLOWING DATA COULD BE USEFUL
5 NEEDED INFORMATION FOR A CORRECT CONSULTING IN THE ENERGY SAVING FIELD
Variable Speed Drive in Pumping StationsADVANTAGES
A HEIGHT FLOW CURVES OR CHARACTERISTICS OF THE SYSTEMB REQUIRED FLOWS AND OPERATION CYCLESC FLUID OR GAS DENSITIESD VALUES OF STATIC AND DYNAMIC HEIGHTE PUMP OR FAN POWER
MINIMUM INFORMATION REQUIRED (GRAPHICS USE)
A REQUIRED FLOWS AND OPERATION CYCLESB PUMP OR FAN POWER (DIFFERENT FLOWS)
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
42
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS2
PART 2
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
43
Speed Control in Induction MotorsINTRODUCTION 1
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
44
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 Introduction
2 Induction motors Control Outlines
3 Speed control in a Squirrel Cage Motor
4 Electronic Outlines for AC Motor Control
SUMMARY ndash PART 2
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
45
1 Induction motor control outlines variable speed drive and softstarters
22 Power ElectronicsPower Electronics technology and experience in power electronics
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
1 INTRODUCTION
3 Basic Outlines- To know the outlines of the
induction motors- Variable speed drives
performance- Softstarters performance- Harmonics in industrial provisions- Electromagnetic compatibility of
VSD- Energy saving in pumps and fans- Applications and control
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
46
Speed Control in Induction MotorsINDUCTION MOTORS CONTROL OUTLINES 2
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
47
INDUCTION MOTORS
The induction motor (asynchronous or squirrel cage) is made up of two main partsThe ROTOR fixed along an axisThe STATOR
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
48
INDUCTION MOTORS
The rotor is built with electronically short-circuit bars through rings at the edges which form the squirrel cage
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
49
INDUCTION MOTORS
Connecting the motor to a 3-phase power supply a rotational magnetic field it is generated in the stator (flux)This is due toThe physical position of the stator windings 3 coils separated physically 120ordmThe current in those windings diphase 120ordm electrically
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
50
INDUCTION MOTORS
The flux lines (arrows) induce currents on the rotor barsWhen a magnetic field acts over a conductor in which a current flow the resultant is a force which produce the torque and therefore the motor rotation
2 INDUCTION MOTORS CONTROL OUTLINES
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ROTATING FIELD
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
51
Speed Control in Induction MotorsSPEED CONTROL IN A SQUIRREL CAGE MOTOR
3
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
52
SPEED CONTROLA squirrel cage motor is a constant speed motorBut speed can be controlled acting on the number of polespoles of the motor and the frequency supplyfrequency supply
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIPMOTOR
TORQUEMAXIMUMTORQUE
STARTINGTORQUE
MOTOR SPEED
raquo Torque ndash Speed curve in a induction motor
MOTORCURRENT
MOTOR SPEED
STARTINGCURRENT
NO LOAD CURRENT
raquo Current ndash Speed curve
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
53
SPEED CONTROL
Method used by electronic speed controllers To vary the frequency supply of the motor
3 SPEED CONTROL IN A SQUIRREL CAGE MOTOR
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY IS VARYING THE FREQUENCY SUPPLY THE BEST METHOD
A high performance in the whole range of speeds is obtained
This method disposes of a continuous variation of the speed that might be electrically through control signals such as 0-10VDC o 4-20mA This makes VSD for AC motors to be the best option for process automation
The available motor torque is constant even at low speeds This offers the possibility to work with any load
It is possible to work with frequencies above 50Hz
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
54
Speed Control in Induction MotorsELECTRONIC OUTLINES FOR AC MOTOR CONTROL
4
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
55
FREQUENCY SUPPLY VARIATION
Torque ndash speed curve evolution when the frequency supply varies
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
raquo Torque ndash Speed curve
OF NOMINALTORQUE
MOTOR SPEED
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
56
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Equivalent circuit per phase can be represented according to
IR Component of load ldquoRealrdquo component that flows through the rotor This current generates the torque and therefore increases as the load of the motor increases
IM ldquoImaginaryrdquo component 90ordm diphased regarding to the ldquorealrdquo component Magnetizing current responsible of the motor flux It is convenient to keep it constant as the load varies
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
57
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Vector diagram of the motor current
Magnetizing current IM is constant regardless of the loadIt is this current which generates the magnetic field in the stator affecting to the motor capacity of producing torque
Real
cur
rent
(Tor
que)
ITTo
tal C
urre
nt
Imaginary current (Magnetizing)
Real
cur
rent
(Tor
que)
ITTo
tal C
urren
t
Imaginary current (Magnetizing)
cos = Power factor
raquo At full load raquo At medium load
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
58
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
WHY VHz CONSTANT
Controlling the voltage applied to the stator (E1) it is possible to control the magnetizing current (IM) and therefore the flux
Increasing the motor speed the slip (S) decreases and the relative frequency decreases too Then the cosR improves the losses inductance is reduced and e Ir decreases
SM Lf
EI
middotmiddotmiddot21
22
2
2
)middot(
SXR
SEI
rr
E1 = Supply voltagef = Supply frequencyLS = Magnetizing inductance of the stator
In a electronic speed controller the motor voltage supply must be adjusted proportionally to the frequency so that the magnetization current remains constant
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
59
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
RELATIONSHIP VOLTAGE ndash FREQUENCY IN A VSD VOLTAGE COMPENSATION AT REDUCED SPEEDS
Voltage increase It is necessary when the load requires a high starting torque (transport bands high inertia load hellip)
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
AREA WHERE THE MAGNETIC FIELD MAKES WEAKER
100
OU
TPU
T VO
LTA
GE
50Hz OUTPUT FREQUENCY
STARTING VOLTAGE
raquo Voltage ndash Frequency relationship in the drive raquo Voltage compensation at reduced speeds
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
60
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
DIAGRAM BLOCK FOR A VARIABLE SPEED DRIVE
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
61
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
INVERTER CIRCUIT
Output waveforms of the inverter bridge
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
62
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
CURRENT IN THE MOTOR WITH SEMI-SQUARED VOLTAGE
raquo Output voltage (quasi-rectangular wave)
Transistor current
Free flow current
raquo Output motor current
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
63
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MODULATION AND WAVE SHAPES OUTPUT VOLTAGE
raquo Modulation and waveforms of the output voltage
CARRIER WAVE
SINUSOIDAL WAVEREFERENCE SIGNAL
SUPERIOR TRANSISTOR ON
INFERIOR TRANSISTOR ON
INVERTER OUTPUT VOLTAGE(REGARDING TO THE MIDDLE POINT IN THE DC BUS)
OUTPUT VOLTAGE BETWEEN PHASES PWM
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
64
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
A triangular signal is compared to a senoidal one in the sinusoidal modulationThe wave shape of the current produced in the motor is very similar to the senoidal one with a very long distortion
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
65
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
OUTPUT WAVES MODULATION
raquo Output voltage modulation
NOMINAL FREQUENCY ndash NOMINAL VOLTAGE
MEDIUM LEVEL FREQUENCY ndash MEDIUM LEVEL VOLTAGE
The width and the number of hollows are electronically adjusted in order to reduce the output voltage as long as the frequency diminishes
New technology vector vector space modulationspace modulation better wave shapes and less commutations
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
66
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
VECTOR SPACE MODULATION
raquo 3-Phase vector
A system of 3-phasic senoidal waves can be represented through three rotating vectors (phasors)
V
C
N
VA
VE
Rotation speed (revsec) FrequencyFrequency
Instantaneous position Status in a cycleStatus in a cycle
Vector length Voltage amplitudeVoltage amplitude
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
67
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ADVANTAGES OF VECTOR SPACE MODULATION VERSUS SINUSOIDAL MODULATION
Small content of harmonics in the motor
Small pulsate pairs
Constant frequency modulation
Better use of voltage supply
Adapted to the wave generation using microprocessor
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
68
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC DEVICES BASED ON COMMUTATION
THYRISTORS Power semiconductor with PNPN structure Currently not used
BIPOLAR TRANSISTORS Based on NPN or PNP structure
ISOLATED GATE BIPOLAR TRANSISTORS (IGBT) the latest generation control realized by mean of voltage the commutation is done by the application of voltage to the gate
Advantages of the IGBTAdvantages of the IGBTbull Less voltage saturation bull Higher commutation frequenciesbull Higher overload capabilitybull Less power demand in the motor circuit
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
69
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
ELECTRONIC CONTROL THE BRAIN OF THE DRIVE
Functioning
It receives the required speed signalIt receives user commands stop starthellipetcIt generates waveforms modulated in vector space technology It commutates the switchesIt controls the current in the motor to protect the drive and the motor from overloadsIt allows to do the necessary adjustments for one application acceleration and deceleration ramps maximum and minimum speedhellipetcIt offers output information motor current frequency start stop failure indicationhellipetc
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
70
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
MONOPHASIC DEVICES
raquo Wiring connections for 230400V motors
Small motors are designed with windings of 230Vac
Drive with 3-phasic input of 400V Control configured with the voltage and the frequency of the motor
Drive with single-phase input of 230Vac
WIRING FOR 230V MOTOR CONNECTION WIRING FOR 400V MOTOR CONNECTION
DELTA CONNECTION OF THE TERMINALS STAR CONNECTION OF THE TERMINALS
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
71
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
REGENERATION
Current operationCurrent operation Motor operationMotor operation Generator operationGenerator operation
2 1 0 -1
Generator torqueGenerator torque
Motor TorqueMotor Torque
0
N2 N1 speedspeed
slipslip
+ve+ve-ve-ve
torquetorque+
ve+ve
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
72
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
LOADS TYPES CONSIDERATIONS
Before choosing the size of the motor and VSD it is necessary to understand the torque-speed characteristics for every single load
100100
Motor speedMotor speed
Constant TorqueConstant Torque Constant PowerConstant Power
TORQUETORQUE POWERPOWER
POW
ERPO
WER
TORQUE
TORQUE
100100 200200
5050
Magnetic field Magnetic field makes weakermakes weaker
Available TORQUE peakAvailable TORQUE peak
POW
ERPO
WERTO
RQUE
TORQ
UE
Motor speedMotor speed50Hz50Hz 100Hz100Hz
100100
200200
6363
Continuous TorqueContinuous Torque
(limited due to the motor (limited due to the motor cooling)cooling)
raquo Relation () between torque and power
raquo Torque loss due to motor cooling
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
73
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
BASIC LOADS TYPESConstant power load Constant power load The torque required by the load increases as the speed decreases Constant power (mills winding machines)
Constant load torque Constant load torque Constant torque at any speed (transport bands presses of printers crane and hoist hellipetc)
raquo Load at constant power raquo Load at constant torque
Required resistant torque
Continuous torque
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Available torque peak
TO
RQ
UE Area for
intermittent operation
Area for continuous operation
Continuous torque
Required resistant torque
Area for intermittent operation
Available torque peak
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
74
4 ELECTRONIC OUTLINES FOR AC MOTOR CONTROL
Speed Control in Induction MotorsVARIABLE SPEED DRIVE amp SOFTSTARTERS
TORQUE ndash SPEED RELATIONSHIP
raquo Torque proportional to the Speed raquo Torque proportional to the Square of the Speed
Available torque peak Area of
intermittent operation
Area of continuous operation
TO
RQ
UE
Continuous torque
Resistant torque required
Speed Resistant torque required
TO
RQ
UE
Available torque peak
Area of intermittent operationArea of continuous
operation
Continuous torque
Speed
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL
Thanks for your attention
PresentationVariable Speed Drives in Pumping Systems AdvantagesSpeed Control in Induction Motors
RealizationPilar Navarro
OrganizationMarketing Department
wwwpower-electronicscomcopy2006 Power Electronics Espantildea SL