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Maxon Motor Presentation
Introductiondrive seminar
Page 1Page 1© 2014, maxon motor ag
maxon seminar:
Drive systems with low power DC motors
Typical performance and its significance Selection of drive components Use in dynamic drive systems
© 2014 maxon motor ag, Sachseln, Switzerland
Learning objectives
The participants … get an overview on the parts of a Servo Drive System and
the interaction between them.
learn to read the data sheets of DC motors, EC motors, gearheads.
know the main properties and application ranges of DC and EC motors and be able to select the correct system.
Introductiondrive seminar
Page 2Page 2© 2014, maxon motor ag
Agenda Electromate Seminar09.30 – 10.15 Motor selection: What is it all about?
– Application and situation analysis – Extracting key load parameters
10.15 – 10.45 Properties of brushed and brushless DC motors– Design variants– Commutation systems: brushed, brushless
10.45 – 11.00 Coffee break11.00 – 11.30 Motor data sheets
– Characteristic motor lines– Operation ranges
11.30 – 12.15 Motor selection example12.15 – 13.00 Lunch13.00 – 13.30 Motor selection example continued13.30 – 14.30 Introduction to ESCON and EPOS Systems
Media
maxon Formulae Handbook– epaper.maxonmotor.ch/formulaehandbook
maxon catalogue– epaper.maxonmotor.ch/en/
Presentation hand-outs www.maxonmotor.com
– Service & Downloads– Service Desk (FAQ)– maxon academy
Overview of the selection steps drive seminar
Page 1 Page 1 © 2013, maxon motor ag
Selection of drive components Systematics of the drive selection Situation analysis, boundary conditions
How is the integration into the environment? Preselection
Determining the load requirements Result: key data for load characterization
© 2012 maxon motor ag, Sachseln, Switzerland
Systematic selection process
Step 1 overview situation
step 2 step 3 step 4 step 5+6 step 7 load drive gear- motor type sensor head winding controller
ambient condition
communication
power
Overview of the selection steps drive seminar
Page 2 Page 2 © 2013, maxon motor ag
Step 1: Gain an overview recognize dependencies
operating mode
operating points
power
control concept
boundary conditions
mechanics
motion profile
control accuracy
analyze problem
checklist
Drive system as a black box environment temperature, atmosphere impacts, vibration …
mechanical power force, torque velocity, speed
electrical power current voltage
quality, accuracy resolution mech. play
task set values commands
emissions electro magnetic heat noise …
boundary conditions dimensions service life …
Overview of the selection steps drive seminar
Page 3 Page 3 © 2013, maxon motor ag
Operating mode
What is a working cycle? How often is it repeated? Which breaks?
continuous operation cyclic operation intermittent Short-time operation
Operating modes continuous (S1)
short term (S2)
working cycles
intermittent (S3)
time
load
Overview of the selection steps drive seminar
Page 4 Page 4 © 2013, maxon motor ag
Control concept What kind of communication?
– communication with higher level host system
Controlled variable – torque, current – speed, velocity – position
Controlled range, accuracy? – position resolution – speed stability
feedback sensor
– set value range – inputs and outputs
Controller: Heart of the drive system
Overview of the selection steps drive seminar
Page 5 Page 5 © 2013, maxon motor ag
Control parameter Feedback, sensor Position Speed, Direction
Encoder Hall sensors
Resolver
Speed, Direction DC Tacho IxR
Sensors in feedback systems
Commands, Set values
Motion Controller
Closed loop system for speed or position
Power
∆𝑝𝑜𝑠
∆𝑡
Task and control accuracy The accuracy of control is the combined result
of all components in a drive system! – resolution, precision
command controller motor gearhead, drive load
sensor
control loop
phase shifts time shifts
mechanical play signal amplification
Overview of the selection steps drive seminar
Page 6 Page 6 © 2013, maxon motor ag
position accuracy – absolute, relative, repeatability – overshoot allowed? – mechanical play in couplings, gearheads, … – encoder resolution and accuracy (linearity)
speed accuracy – Corrected in what time frame? – min. speed nmin by encoder resolution – max. speed nmax by limiting frequency of the encoder – Speed ripple by current and / or torque ripple
electronic components – resolution of A/D-converters, frequency voltage converter – bandwidth, temperature influences
Accuracy of drive systems
t
r
Time and frequency aspects
Overview of the selection steps drive seminar
Page 7 Page 7 © 2013, maxon motor ag
Power flow
energy is not stored: Power flow – Power: a „constant“ reference value of the drive system
Power consists of 2 components: – voltage and current – velocity and force or speed and torque
– One components can only increase at the expense of the other.
power supply controller motor gearhead,
drive load
sensor
Losses
Pel = U * I Pmech = v * F Pmech = ω * M
Transformation of power
transformation of power – electrical to electrical:
– electrical to mechanical:
– mechanical to mechanical:
efficiency η describes losses
η = 90% η = 90 – 95%
optimum η = 80 - 90%
η = 90% per stage worm gear < 40%
ball screw spindle η = 80 - 90% trapezoidal spindle 40%
Overview of the selection steps drive seminar
Page 8 Page 8 © 2013, maxon motor ag
Drive design: linear – rotation Drive elements and coupling with load relative position of motor and load
– e.g. bridge a distance with a belt
Mechanical drive concept
Motors up to 500W
stepper motors
asynchronous motors
synchronous motors
DC motors
BLDC motors Stator winding
magnetic rotor
DC behavior (shunt)
n
M I
linear motors f
start
M
Overview of the selection steps drive seminar
Page 9 Page 9 © 2013, maxon motor ag
Particular boundary conditions dimensions
service life – specific depending on load cycle, ambient conditions and application – given as service hours or numbers of working cycles – limited by the weakest component
temperature, atmosphere
– can influence the achievable power and service life
noise, vibration – specific depending on load cycle, mounting
and ambient conditions, application – influences on service life
Interfaces: Connections
electrical connections – cable type, cable length, colours – plug – strain relief
mechanical interface – mounting type, mounting pilot, threads, number and location of bolt
holes – output shaft: length, diameter, flats – drive elements, pinions, couplings – tolerances
Overview of the selection steps drive seminar
Page 10 Page 10 © 2013, maxon motor ag
Definition of the load requirements
motion profile and operation points
mass inertia and acceleration
forces and torques
Key values
n(t), M(t) v(t), F(t)
Operating points Pair of
– torque and speed – force and velocity
standard representation: (x,y) = (M,n) or (F,v)
speed n velocity v
torque M force F
acceleration deceleration
dwell
Overview of the selection steps drive seminar
Page 11 Page 11 © 2013, maxon motor ag
Operating point and motion profile
(M1,n1) acceleration friction and acceleration (M2,n2) const. speed friction only (M3,n3) deceleration friction helps during deceleration (M4,n4) dwell depending on friction
n
M
t
n
1 2 3 1 4
1 2
3 4
extreme operating point
Key load data for characterization
maximum load average effective load (RMS)
maximum velocity or speed vmax / nmax
duration of the maximum load Δtmax
duration of a load cycle Δttot
required position resolution Δs required speed accuracy Δn
Fmax / Mmax F / M
t
FRMS / MRMS
Δtmax
Δttot
...MtMtMtt1M 2
33222
211
totRMS
Overview of the selection steps drive seminar
Page 12 Page 12 © 2013, maxon motor ag
Example: Conveyor belt for samples
pulley diameter 100 mm maximum mass on belt 3 kg coefficient of friction on
support approx. 0.3 friction force (empty belt) approx. 40 N feed velocity 0.5 m/s supply voltage 24 V
Step 1: Situation Analysis What information is missing? operating mode current task of the drive / setpoints maximum length / diameter service life movement quality emissions environmental conditions control concept
pulley diameter 100 mm maximum mass on belt 3 kg coefficient of friction on
support approx. 0.3 friction force (empty belt) approx. 40N feed velocity 0.5 m/s supply voltage 24 V
Overview of the selection steps drive seminar
Page 13 Page 13 © 2013, maxon motor ag
Step 2: Load requirements
What information is missing? acceleration value motion profiles Mass (rollers, conveyor belt) Forces / torques …….
pulley diameter 100 mm maximum mass on belt 3 kg coefficient of friction on
support approx. 0.3 friction force (empty belt) approx. 40N feed velocity 0.5 m/s supply voltage 24 V
Example: Conveyor belt for samples
speed nL =
feed force FL =
torque ML =
power PL =
acceleration Fa =
W25495.0Fv LL
Nm5.24921.0F
2d
L
1
2dL min100
05.05.030v3030
N50409401033.0Fgm R
N5.115.03
tvm L
Overview of the selection steps drive seminar
Page 14 Page 14 © 2013, maxon motor ag
Example conveyor belt: Key values
Looking for a drive that can accomplish the following: maximum speed nmax 100 rpm
average torque Meff approx. 2.5 Nm maximum torque Mmax approx. 2.7 Nm duration of Mmax 1s
100 rpm
2.5 2.7 Nm
n
M
maxon DC and EC motors drive seminar
Page 1 Page 1 © 2013, maxon motor ag
Top
3. Low power motors
DC motors EC motors Structure, properties, options
© 2012, maxon motor ag, Sachseln, Switzerland
Top
DC motor designs conventional, slotted
e.g. Dunkermotor
coreless e.g. maxon
DC motors - overview
maxon DC and EC motors drive seminar
Page 2 Page 2 © 2013, maxon motor ag
Top
Conventional DC motor el. connections
housing (magn. return)
winding
commutator
brush system
iron core
permanent magnet (external)
flange
DC motors - overview
Top
Coreless maxon DC motor (RE 35)
el. connections
self supporting winding
commutator
brushes
permanent magnet (in the centre)
housing (magnetic return)
flange
commutator plate
shaft
ball bearing
ball bearing
press ring
press ring
DC motors - overview
maxon DC and EC motors drive seminar
Page 3 Page 3 © 2013, maxon motor ag
Top
What makes maxon motors special? no cogging
– no soft magnetic teeth to interact with the permanent magnet – smooth motor running even at low speed – less vibrations and audible noise – any rotor position can easily be controlled – no nonlinearities in the control behavior
compact design – more efficient design of the magnetic circuit – compact magnet, high power density – small rotor mass inertia – high dynamics
DC motors - overview
Top
What makes maxon motors special? no iron core - no iron losses
– constantly impressed magnetization – high efficiency, up to over 90% – low no-load current, typically < 50 mA
no saturation effects in the iron core – Even at the highest currents the produced torque
is proportional to the motor current. – stronger magnets = stronger motors
low inductance – less brush fire, longer service life – less electromagnetic emissions – easier to suppress interferences: capacitor between connections,
ferrite core at motor cable
DC motors - overview
maxon DC and EC motors drive seminar
Page 4 Page 4 © 2013, maxon motor ag
Top
maxon DC motor families DCX motor range
– configurable system – high performance motor with NdFeB magnet – high torques and speeds
RE motor range – high performance motor with NdFeB magnet
A-max motor range – attractive price-performance ratio – DC motor with AlNiCo magnet
RE-max motor range – performance between RE and A-max
6 - 65mm
12 - 32mm
13 - 29mm
10 - 35mm
DC motors - variants
Top
DC commutation systems
Precious metal bronze brush body with plated silver contact area silver alloy commutator smallest contact and brush resistance (50 mW) CLL for high service life
Graphite graphite brush with 50%
copper copper reduces the contact
and brush resistance copper commutator graphite serves as lubricant spring system (schematic)
DC motors – commutation
maxon DC and EC motors drive seminar
Page 5 Page 5 © 2013, maxon motor ag
Top
DC commutation: Characteristics Graphite + well suited for high currents and
peak currents + well suited for start-stop and
reversing operation + larger motors (>approx. 10 W)
higher friction, higher no-load
current not suited for small currents higher audible noise higher electromagnetic emissions higher costs
Precious metal + well suited for smallest currents
and voltages + well suited for continuous
operation + smaller motors + very low friction + low audible noise + low electromagnetic interference + cost effective not suited for high current and
peak currents not suited for start-stop operation
DC motors – commutation
Top
EC motors
2/4-pole EC motor internal rotor
Multipole EC flat motor external rotor
electronic commutation – with Hall sensors – sensorless – sinusoidal commutation
Multipole ECi motor internal rotor
EC motors - overview
maxon DC and EC motors drive seminar
Page 6 Page 6 © 2013, maxon motor ag
Top
Brushless DC motor names: EC motor, BLDC motor motor behavior similar to DC motor
– design similar to synchronous motor (3 phase stator winding, rotating magnet)
– the powering of the 3 phases according to rotor position
main advantages: higher life, higher speeds slotless windings: no magnetic detent, less vibrations
becomes more attractive – costs and size of electronics – strength of magnets
EC motors - overview
Top
maxon EC motor families
features in common
EC motors - variants
maxon DC and EC motors drive seminar
Page 7 Page 7 © 2013, maxon motor ag
Top
maxon EC motor families maxon EC motor
– high speeds and torques
EC-max – good value for money – not optimized for performance: relatively high torque – speeds up to 12’000 min-1
EC-4pole – optimized for performance: high torque – speeds up to 25’000 min-1
EC flat motor – very good value for money – speeds up to 12’000 min-1
– relatively large amount of torque EC motors - variants
Top
maxon EC motor
el. connections winding and Hall sensors
housing
PCB with Hall sensors
3 phase knitted maxon winding
magn. return: laminated iron stack
rotor (permanent magnet)
balancing rings
control magnet
preloaded ball bearings
EC motors - variants
maxon DC and EC motors drive seminar
Page 8 Page 8 © 2013, maxon motor ag
Top
EPOS2
block sine
Hall sensors
commutation type
rotor position
feedback
maxon controller families
encoder (+ HS) sensorless
ESCON DECS EPOS2
common goal: applying the current to get the maximum torque perpendicular magnetic field orientation of
- rotor (permanent magnet) - and stator (winding)
knowledge of rotor position with respect to winding
Electronic commutations systems
ESCON
EPOS3 EtherCAT
EC motors – electronic commutation
Top
1 1 0 0 0 1 1 0 1 1 1 0 0 0 0 0 0 1 1 1 0
0° 60° 120° 180° 240° 300° 360° rotation angle
south
north
rotor position from Hall sensor signals
Hall sensor
control magnet
EC-max and EC flat: Power magnet is probed directly
Block commutation
EC motors – electronic commutation
maxon DC and EC motors drive seminar
Page 9 Page 9 © 2013, maxon motor ag
Top
Block commutation +
–
HS3
HS1
HS2
commutation electronics
power stage (MOSFET)
Phase 1
Phase 2
Phase 3
rotor position feedback
com
mut
atio
n lo
gics
EC motor
(magnet, winding, sensor)
EC motors – electronic commutation
Top
DC and EC motor: Comparison DC motor + simple operation and
control, even without electronics
+ no electronic parts in the motor
brush commutation system limits motor life
max. speed limited by commutation system
EC motor + long life, high speeds preloaded ball bearings
+ no brush fire
iron losses in the magnetic return
needs electronics to run more cables more expensive
electronic parts in the motor (Hall Sensor)
Comparison DC and EC
maxon DC and EC motors drive seminar
Page 10 Page 10 © 2013, maxon motor ag
Top
DC and EC motor: Comparison
max. speed power density torque density mech. time (min-1) (W/cm3) (mNm/cm3) const. (ms)
maxon motor family RE (DC) EC EC-max (20 … 100 Watt) EC-4pole EC-flat EC-i
50 000 min-1 10 W/cm3 2 mNm/cm3 10 ms
25 000 min-1 5 W/cm3 1 mNm/cm3 5 ms
Comparison DC and EC
maxon Motor Data and Operating Ranges drive seminar
Page 1 Page 1 © 2013, maxon motor ag
Top
Motor data and operating ranges of maxon DC motors
Motor behaviour: speed-torque line, current Motor data and operating ranges
© 2012, maxon motor ag, Sachseln, Switzerland
DC motor as an energy converter electrical in mechanical energy
– speed constant – torque constant – speed-torque line
applies to DC and EC motors – "EC" = "brushless DC" (BLDC)
IUPel
2J IRP
MnPmech 30
Overview
maxon Motor Data and Operating Ranges drive seminar
Page 2 Page 2 © 2013, maxon motor ag
Characteristic motor data describe the motor design and general behaviour independent of actual voltage or current
strongly winding dependent values (electromechanical)
almost independent of winding (mechanical)
10 Terminal resistance (phase to phase) R Ω 11 Terminal inductance (phase to phase) L mH 12 Torque constant kM mNm / A 13 Speed constant kn rpm / V
14 Speed / torque gradient Dn/DM rpm / mNm 15 Mechanical time constant tm ms 16 Rotor mass inertia JMot gcm2
Characteristics
Different windings
high resistance winding thin wire, many turns high rated voltage low rated and starting
currents low specific speed (min-1/V) high specific torque (mNm/A)
low resistance winding thick wire, few turns low rated voltage high rated and starting
currents high specific speed (min-1/V) low specific torque (mNm/A)
R
Characteristics
maxon Motor Data and Operating Ranges drive seminar
Page 3 Page 3 © 2013, maxon motor ag
Electromechanical constants
Torque constant kM – produced torque is proportional to motor current – unit: mNm / A
Speed constant kn – law of induction: changing flux in a conductor loop – mostly used for calculating no-load speeds n0
– unit: min-1 / V
Correlation – kM and kn are inverse, but in different units – expressed in the units from catalog:
Ukn n0
indn Ukn
IkM M
Vmin
AmNm000'30kk
1
nM
Characteristics
Motor as an electrical circuit
applied motor voltage U:
+ _
EMF L R
I U EMF: induced voltage Uind
(winding) resistance R winding inductance L • voltage losses over L can be
neglected in DC motors
indtI UIREMFIRLU
IRUUind
Mn kMRU
kn
MMnUkn
MkR000'30Ukn
n
2M
n
D
D
Characteristics
maxon Motor Data and Operating Ranges drive seminar
Page 4 Page 4 © 2013, maxon motor ag
Speed-torque line speed n
torque M
U > UN
U = UN
MH
n0
Dn
DM
current I IA
Ukn n0
MMnUkn n
D
D
Characteristics
Speed-torque gradient
speed n
torque M MH
n0 Dn
DM
strong motor: • flat speed-torque line, small Dn/DM • not sensitive to load changes • e.g. strong magnet, bigger motor
weak motor: • steep speed-torque line, high Dn/DM • sensitive to load changes • e.g. weak magnet, smaller motor
by how much is the speed reduced Dn, if the output motor torque is enhanced by DM?
M1, n1
M2, n2
iH
i2M M
nRk000'30
Mn
D
D
Characteristics
maxon Motor Data and Operating Ranges drive seminar
Page 5 Page 5 © 2013, maxon motor ag
Winding series
speed-torque gradient basically constant for the winding series constant filling factor: a constant amount of copper fills the air gap
n
M
at U constant
thick wire
thin wire
numerous winding variants adjust electrical input power (voltage,
current of power supply) mechanical output power
(speed, torque)
Characteristics
Values at nominal voltage at rated voltage UN
at rated current IN
Motor at stall – resulting stall torque MH
– resulting starting current IA
rated working point – resulting rated speed nN
– resulting rated torque MN
No-load operating point – resulting no-load speed n0
– resulting no-load current I0
describe the special working points:
n
M Values at nominal voltage
maxon Motor Data and Operating Ranges drive seminar
Page 6 Page 6 © 2013, maxon motor ag
Thermal motor data describe the motor heating and thermal limits depend strongly on mounting conditions standard mounting:
heating and cooling – thermal resistance housing-ambient Rth2
– thermal resistance winding-housing Rth1
– thermal time constant of winding tthW
– thermal time constant of motor tthS
temperature limits – ambient temperature range – max. winding temperature Tmax
plastic plate
horizontal mounting
free convection at 25 °C ambient temperature
Specifications
Mechanical motor data
max. permissible speed – limited by bearing life considerations (EC) – limited by relative speed between collector and
brushes (DC)
axial and radial play – suppressed by a preload
axial and radial bearing load – dynamic: in operation – static: at stall
axial press fit force (shaft supported)
describe maximum speed and the properties of bearings
F5 Fd
d l
Specifications
maxon Motor Data and Operating Ranges drive seminar
Page 7 Page 7 © 2013, maxon motor ag
maxon standard tolerances
n
M
1.1 1.0
1.0 0.86 1.16
0.9
Sources – winding resistance ± 7 % – magnetic properties ± 8 % – friction and losses
Results – general tolerance level 5 to 10 % – tolerance in no-load current ± 50 % – tolerance in no-load speed ± 10 %
weaker magnet => enhanced n0 stronger magnet => reduced n0
Values at nominal voltage
Influence of temperature temperature coefficients
Cu + 0.39 % per K AlNiCo - 0.02 % per K Ferrite - 0.2 % per K NdFeB - 0.1 % per K
temperature resistance magnetic properties example: RE motor DT = + 50K R: + 19.5 % kn + 5 % (no-load speed)
kM - 5 % (more current!)
stall torque MH : - 22 %
Values at nominal voltage
maxon Motor Data and Operating Ranges drive seminar
Page 8 Page 8 © 2013, maxon motor ag
Motor limits: operation ranges
- lower ambient temperature - good heat dissipation
- higher ambient temperature - heat accumulation
Speed n
continuous operation
short term operation
MN IN
torque M current I
nmax
Operating Range
Short-term operation overload
load MN 2MN 3MN 4MN
overload duration
5tW
4tW
3tW
2tW
1tW
continous operation
motor may be overloaded for a short time and repeatedly – limit: max. permissible winding temperature – depends on thermal time constant of winding tW and amount
of overload
torque M
thermally prohibitted short term operation permissible
short term operation
Operating Range
Examples for motor and drive selection drive seminar
Page 1 Page 1 © 2013, maxon motor ag
Examples for motor and drive selection Continuous operation Cyclic operation maxon selection program
© 2012 maxon motor ag, Sachseln, Switzerland
Systematic selection process
Step 1 overview situation
step 2 step 3 step 4 step 5+6 step 7 load drive gear- motor type sensor head winding controller
ambient condition
communication
power
Examples for motor and drive selection drive seminar
Page 2 Page 2 © 2013, maxon motor ag
Step 5: Motor selection conveyor belt
selecting the motor type selection of the winding
planetary Gearhead GP 32 A – reduction 51:1
Motor requirements (key values) – Speed 5100 min-1
– average torque 70 mNm
– maximum torque about 75 mNm, 1s
Selection criteria motor type
Commutation (Service life)
Sensor
Shaft Bearing (Service life)
Electrical connection
Ambient condition
Examples for motor and drive selection drive seminar
Page 3 Page 3 © 2013, maxon motor ag
Motor type selection Combination with
selected gearhead Nominal torque
(continuous torque) max. torque max. permissible
speed
MN
n
M
continuous operation
short term operation
deceleration acceleration
nmax NRMS MM
maxon Modular System + motor RE 25, 10W RE 25, 20W A-max 26 RE-max 29
+ motor RE 30, 60W RE 35, 90W A-max 32 EC 32, 80W
according motor type MN suited? maxon modular system
Motor type selection
A-max 26
< 30 mNm RE 25
RE-max 29
RE 30
RE 35
too weak
< 18 mNm
< 30 mNm
too weak
too weak
ca. 80 mNm
100 mNm
good
strong
EC 32
A-max 32
EC 32 flat
< 45 mNm
< 45 mNm
too weak
too weak
< 10 mNm too weak
Examples for motor and drive selection drive seminar
Page 4 Page 4 © 2013, maxon motor ag
Step 6: Winding selection Goal: Reach the required speed at maximum possible motor
voltage under maximum load for a given motor size (motor type) this means: sufficiently high
speed constant
motmottheor,0 MMnnn
mot
theor,0theor,nn U
nkk
speed n
torque M
speed-torque line high enough for the required load speed
Mmot
n0,theor
nmot nmot, Mmot
speed-torque line too low for the required load speed
Example: Conveyor belt for samples
n [rpm]
M
1motmottheor,0 min57007095100M
Mnnn
70 mNm
5100
Vrpm270
215700
Un
kkmot
theor,0theor,nn
select motor 310007: – speed constant kn = 369 min-1/V
needed current – with torque constant kM
A8.215.09.25
70
Ik
MI 0M
maxmax
5700
Feedback and Motion Control maxon drive seminar
Page 1 Page 1 Page 1 © 2013, maxon motor ag
Feedback and Motion Control Feedback systems
– Specifically: Encoder Properties of controllers
– control value – performance, motor type – communication, signal processing
© 2012 maxon motor ag, Sachseln, Switzerland
Motion Control System Overview Power Supply
I/O
Encoder Motor
Gearhead
Load
CAN
Supervisor / Master (PLC / PC)
Motion Controller
v(t), F(t)
Feedback and Motion Control maxon drive seminar
Page 2 Page 2 Page 2 © 2013, maxon motor ag
Sensors in feedback systems
Commands, Set values
Motion Controller
Closed loop system for speed or position
Power
Control parameter Feedback, sensor Position Speed, Direction
Encoder Hall sensors
Resolver
Speed, Direction DC Tacho IxR
∆𝑝𝑜𝑠
∆𝑡
Drive component: Controller
Feedback and Motion Control maxon drive seminar
Page 3 Page 3 Page 3 © 2013, maxon motor ag
mmc product families controller
family EPOS ESCON
control loops current control
speed control
position control
system architecture
commanded by master system
commanded by digital and analog inputs
setup graphical user interface (Studios)
feedback sensors
needed feedback: • EC: encoder and Hall
sensor • DC: encoder
possible feedback: • encoder
• Hall sensor (EC) • DC tacho (DC)
Configuration – EPOS/ESCON Studio
Configuration
Graphical User Interface
(GUI)
Operation mode Current control Speed control Position control
Motor type DC BLDC Commutation
Feedback type Encoder (resolution) Hall sensor DC Tacho
Communication Bus types Baud rates …
Inputs / Outputs Stop Direction Enable - disable
Ready Speed comparator ….
Selection example – step by stepDrive seminar
Page 1Page 1© 2013, maxon motor ag
Selection ofdrive components
The systematics of the drive selection on a practical application example
© 2013 maxon motor ag, Sachseln, Switzerland
Selection example – step by stepDrive seminar
Page 2Page 2© 2013, maxon motor ag
Step 1: Situation Analysis
step 2 step 3 step 4 step 5+6 step 7load drive gear- motor type sensor
head winding controller
ambient condition
communication
power
Step 1overviewsituation
What information is missing?
operating mode, motion profile– acceleration– inertias (rollers, belt)
current power supply
control concept, variable– set value– movement quality
maximum length / diameter
service life
environmental conditions– emissions
Given: pulley diameter 100 mm maximum mass on belt 15 kg coefficient of friction on
support approx. 0.2 friction force (empty belt) approx. 30 N feed velocity 0.5 m/s supply voltage 24 V
Selection example – step by stepDrive seminar
Page 3Page 3© 2013, maxon motor ag
Step 2: Load Requirements
step 2 step 3 step 4 step 5+6 step 7load drive gear- motor type sensor
head winding controller
ambient condition
communication
power
Step 1overviewsituation
Conveyor belt: load data
Maximum load speed
feed force
acceleration
power
𝑣𝐿 = 0.5𝑚
𝑠
𝐹𝐿 = 𝐹𝑅 + 𝜇 ∙ 𝑚 ∙ 𝑔 = 30 + 0.2 ∙ 15 ∙ 9.8 ≅ 60𝑁
𝑃𝐿 = 𝑣𝐿 ∙ 𝐹𝐿 = 0.5 ∙ 60 = 30𝑊
𝐹𝑎 = 𝑚 ∙∆𝑣𝐿∆𝑡
= 15 ∙0.5
0.5= 15𝑁
Selection example – step by stepDrive seminar
Page 4Page 4© 2013, maxon motor ag
Conveyor belt: Key values load
Looking for a drive that can accomplish the following: maximum velocity vmax = 0.5 m/s average force Feff = approx. 60 N maximum force Fmax = approx. 80 N duration of Fmax Δtmax = 0.5 s
0.5 m/s
60 N 80 N
v
F
Step 3: Drive
ambient condition
communication
power
Step 1overviewsituation
step 2 step 3 step 4 step 5+6 step 7load drive gear- motor type sensor
head winding controller
Selection example – step by stepDrive seminar
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Conveyor belt: load data gear
maximum speed
average torque
maximum torque
𝑛𝐺 =30𝜋∙ 𝜔 = 30
𝜋∙𝑣𝐿𝑑2
= 30𝜋∙0.5
0.05≅ 100𝑟𝑝𝑚
𝑀𝐺,𝑒𝑓𝑓 =𝑑
2∙ 𝐹𝐿 =
0.1
2∙ 60 = 3.0𝑁𝑚
𝑀𝐺,𝑚𝑎𝑥 =𝑑
2∙ 𝐹𝑚𝑎𝑥 =
0.1
2∙ 80 = 4.0𝑁𝑚
Example conveyor belt: Key values
Looking for a drive that can accomplish the following: maximum speed nG,max = 100 rpm average torque MG,eff = approx. 3.0 Nm maximum torque MG,max = approx. 4.0 Nm duration of Mmax Δtmax = 0.5 s
100 rpm
3.0 4.0 Nm
n
M
Selection example – step by stepDrive seminar
Page 6Page 6© 2013, maxon motor ag
Step 4: Gearhead selection
ambient condition
communication
power
Step 1overviewsituation
step 2 step 3 step 4 step 5+6 step 7load drive gear- motor type sensor
head winding controller
Step 4: Gearhead selection
Looking for a drive that can accomplish the following: maximum speed nG,max = 100 rpm average torque MG,eff = approx. 3.0 Nm maximum torque MG,max = approx. 4.0 Nm duration of Mmax Δtmax = 0.5 s
?
Selection example – step by stepDrive seminar
Page 7Page 7© 2013, maxon motor ag
Limits gear selection
outputspeed n
outputtorque M
MN
continuousoperation
short termoperation
Mmax
Reduction out of input and output speeds:
torque MN > MG,eff
nmax,L
nmax,in
nmax,L
𝑖 <𝑛𝑚𝑎𝑥,𝑖𝑛
𝑛𝑚𝑎𝑥,𝐿
Selection Guide maxon Gear
3 Nm
Selection example – step by stepDrive seminar
Page 8Page 8© 2013, maxon motor ag
Conveyor belt: Gearhead selection
planetary gearhead GP 32 C– continuous torque 3 Nm (at least 2 stages)– max. input speed 8000 rpm
– max. reduction
– selected reduction 79:1– efficiency ηG 70 %
requirements motor (key values)– speed
– torque
𝑖 <𝑛𝑚𝑎𝑥,𝑖𝑛
𝑛𝑚𝑎𝑥,𝐿=8000
100= 80: 1
𝑛𝑚𝑜𝑡 = 𝑛𝐺 ∙ 𝑖 = 100 ∙ 79 = 7900 𝑟𝑝𝑚
𝑀𝑚𝑜𝑡 =𝑀𝐺
𝑖 ∙ 𝜂𝐺=
3.0
79 ∙ 70%= 54 𝑚𝑁𝑚
Conveyor belt: Key values motor
Looking for a motor that can accomplish the following: maximum speed nmax = 7900 rpm average torque Meff = 54 mNm maximum torque Mmax = 72 mNm duration of Mmax Δtmax = 0.5 s
7900 rpm
54 72 mNm
n
M
Selection example – step by stepDrive seminar
Page 9Page 9© 2013, maxon motor ag
Step 5+6: Selection motortyp & winding
ambient condition
communication
power
Step 1overviewsituation
step 2 step 3 step 4 step 5+6 step 7load drive gear- motor type sensor
head winding controller
Step 5: Motor type selection
MN M
continuousoperation
short term operation
Nominal torque MN > 54 mNm
max. permissible speed > 7900 rpm
Motor type according to modular systemRE 25RE 30RE 35A-max 26A-max 32RE-max 29EC 32EC-max 22, 25WEC-max 30, 40WEC-4pole 22EC flat 32EC-i 40
Selection example – step by stepDrive seminar
Page 10Page 10© 2013, maxon motor ag
Further selection criteria motor type
Commutation (Service life)
Sensor
ShaftBearing(Service life)
Electrical connection
Ambient condition
Conveyor belt motor typeMotor type according to modular system
Nominal torque MN
suitability
RE 25 < 30 mNm Too weak, with brushesRE 30 ca. 90 mNm OK, but with brushesRE 35 ca. 100 mNm strong, but with brushesA-max 26 < 18 mNm too weak, with brushesA-max 32 < 45 mNm too weak, with brushes, nmax= 6000 rpmRE-max 29 < 30 mNm too weak, with brushesEC 32 < 45 mNm too weakEC-max 22, 25W < 23 mNm too weakEC-max 30, 40W < 34 mNm too weak, (60W version => 63 mNm)EC-4pole 22 < 64 mNm OK, only 120W version, builds longEC flat 32 < 23 mNm too weakEC-i 40 < 70 mNm OK
Selection example – step by stepDrive seminar
Page 11Page 11© 2013, maxon motor ag
Step 6: Winding selection Goal: Reach the required speed at maximum possible motor voltage
under maximum load for a given motor size (motor type) this means: sufficiently high speed
constantspeed n
torque M
speed-torque line high enough for the required load speed
Mmot
n0,theor
nmot
nmot, Mmot
speed-torque line too low for the required load speed
𝑛0,𝑡ℎ𝑒𝑜𝑟 = 𝑛𝑚𝑜𝑡 +∆𝑛
∆𝑀∙ 𝑀𝑚𝑎𝑥
𝑘𝑛 > 𝑘𝑛,𝑡ℎ𝑒𝑜𝑟 =𝑛0,𝑡ℎ𝑒𝑜𝑟𝑈𝑚𝑜𝑡
Example: Conveyor belt for samples
n[rpm]
M72 mNm
7900 select motor 311537:– speed constant kn = 497 rpm/V
needed current – with torque constant kM
9100
𝑛0,𝑡ℎ𝑒𝑜𝑟 = 𝑛𝑚𝑜𝑡 +∆𝑛
∆𝑀∙ 𝑀𝑚𝑎𝑥 = 7900 + 17 ∙ 72 ≅ 9100
𝑘𝑛 > 𝑘𝑛,𝑡ℎ𝑒𝑜𝑟 =𝑛0,𝑡ℎ𝑒𝑜𝑟𝑈𝑚𝑜𝑡
=9100
22= 415
𝑚𝑖𝑛−1
𝑉
𝐼𝑚𝑎𝑥 =𝑀𝑚𝑎𝑥
𝑘𝑀+ 𝐼0
=72
19.2+ 0.166 = 3.9 A
Selection example – step by stepDrive seminar
Page 12Page 12© 2013, maxon motor ag
Step 7: Sensor and controller
ambient condition
communication
power
Step 1overviewsituation
step 2 step 3 step 4 step 5+6 step 7load drive gear- motor type sensor
head winding controller