PPT -2 ( Static Rotor Resistance Control)

8/9/2019 PPT -2 ( Static Rotor Resistance Control)

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ALPHA BREATHING


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Solid State Drives

Unit III

Induction Motor Drives

TOPIC: Static Rotor resistance

control & V/ F Control


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EVOCATION


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Rotor resistance control

Conventional rotor resistance control

Static rotor resistance control


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Static rotor resistance control


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Closed loop control


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Speed Control of IM

Variable FrequencSpeed control aboverated !base" s#eedRequires the use of PWM inverters to control frequenc of

!otor

"requenc increased #i$e$ sincreased%

Stator volta&e held constant at rated value

Air&ap 'u( and rotor current decreases

)eveloped torquedecreasesTe#*+s%

"or control ,elo-,ase speed .use ConstantVolts/$% !ethod

8


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Constant Volts+/0 #V+f%Control

Air&ap 'u( in the !otor is related to the inducedstator volta&e E11

"or belo base s#eed operation1"requenc reduced at rated Vs 2 air&ap 'u(

saturates#f3agand enters saturation re&ion oh 42/ curve%12 e(cessive stator currents 'o-

2 distortion of 'u( -ave2 increase in core losses and stator copper loss/ence3 5eep ag'rated (u)stator volta&e Vs *ust be reduced #ro#ortional

to reduction in f #i$e$ !aintainin& Vs/f ratio%9

f

Eag

1=f

Vs Assu!in& s*all volta&edrop across Rsand Lls


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Ma($ torque re!ains al!ostconstant

"or lo s#eed operation1can6t i&nore volta&e drop

across Rsand Lls#i$e$ E*Vs%poor torque capa,ilit

#i$e$ torque decreased at lo-speeds sho-n , dottedlines%

stator volta+e *ust beboosted . to co!pensate forvolta&e drop at Rsand Llsand !aintain constant ag

"orabove base s#eedoperation #f 7 frated%1stator volta&e !aintained at

rated valueSa!e as Variable

Frequenccontrol #refer to

slide *8% 10

s

sVT

2

maxf

Eag

1=f

Vs


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11

Vrated

frated

9inear o:set

Non2linear o:set . varies -ith Is,oost

Vsvs- frelation in Constant

Volts/$% drives

Vs

f

.inear osetcurve .for hi&h2startin&torque loadse*#loed 0or

*osta##lications

1on2linearoset curve .for lo2

startin+torque loads

,oost2 toco!pensate forvolta&e drop atRsand Lls


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"or operation at frequenc Kti!es rated frequenc1

fs; Kfs3rateds; Ks3rated #*%

#Note1 in #*% 3 speed is &iven as !echanicalspeed%

Stator volta&e1

#

%

The !a(i!u! torque is then &iven ,1

#?%

-here sand Vsare calculated fro! #*% and#


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1%

"ield Wea5enin& Mode #f7 frated%

Reduced 'u( #since Vsis

constant%

Torque reducesConstant Poer

3rea!above base s#eed"

ConstantTorque3rea

!belo bases#eed"

Rated #4ase%frequenc

Note1Operationrestricted,et-eensnchronousspeed and T!a(for

!otorin& and

,ra5in& re&ions3i$e$ in the linear


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1&

Constant Poer3rea

ConstantTorque 3rea


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Constant Volts+/0 #V+f% Control. Open2loop I!ple!entation

1'

PWM

Volta&e2SourceInverter#VSI%

Note1 e; s; snchronous

speed


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Constant Volts+/0 #V+f%Control . Open2loop

I!ple!entation Most popular speed control !ethod ,ecause it is easto i!ple!ent

@sed in lo2#er0or*ance a##lications -here precise speed control unnecessar

Speed co!!and s 2 pri!ar control varia,le Phase volta&e co!!and Vs &enerated fro! V+f relation

#sho-n as the B6 in slide


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I!ple!entationPro,le!s in open2loop drive operation1Motor speed not controlled precisel

pri!ar control varia,le is snchronous speed s

actual !otor speed risless than s due to slsl depends on load connected to !otor

sl cannot ,e !aintained since rnot !easuredcan lead to operation in unsta,le re&ion of T2characteristicstator currents can e(ceed rated value . endan&erin&

inverter2converter co!,ination

Pro,le!s #to an e(tent% can ,e overco!e ,1Open2loop Constant Volts+/0 )rive -ith Slip

Co!pensation

Closed2loop i!ple!entation 2 havin& outer speedloop -ith slip re&ulation

19

( )

( )sls

mr

P

P

=

=

2

2


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Constant Volts+/0 #V+f% Control. Open2loop I!ple!entation

0

SlipCo!pensato

r

IdcVdc ; Vd

sl

r

O#en2loo# Constant Volts/$% Drive it4 Sli#Co*#ensation2 Slip speed is esti!ated and added to the referencespeed r

Note1 e; s; snchronous

speed


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I!ple!entation /o- is sl esti!ated in

the Slip Co!pensator

@sin& T2curve3 slTe

slcan ,e esti!ated ,esti!atin& torque-here1

#F%

#G%

1

O#en2loo# Constant Volts/$% Drive it4 Sli#Co*#ensation

s

SCLin

s

ag

e

PPPT

lossesinverter==

dcdcin IVP =Note1 In the H&ure3slip; sl; slip speed

sn; s; snchronous

speedratedsl

ratede

esl

T

T,

,

=

#%


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Constant Volts+/0 #V+f% Control. Closed2loop I!ple!entation

O#en2loo# sste*#as in slide


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Constant Volts+/0 #V+f% Control. Closed2loop I!ple!entationReference !otor speed r is co!pared to the actual

speed rto o,tain the speed loop errorSpeed loop error &enerates slip co!!and sl fro! PI

controller and li!iter9i!iter ensures that the sl is 5ept -ithin the allo-a,le slip

speed of the !otor #i$e$ sl slip speed for !a(i!u! torque%sl is then added to the actual !otor speed rto

&enerate snchronous speed co!!and s #or frequencco!!and%s &enerates volta&e co!!and Vs fro! V+f relation

4oost volta&e is added at lo- speedsConstant volta&e applied a,ove ,ase speed

Sche!e can ,e considered open loop torque control#sinceTs% -ithin speed control loop

#


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What is the missing number in Triangle Four?


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What is the missing number in Triangle Four?

The product of the two largest

minus the suare of the smallest,

!o the missing number is "#$1% & 2'

READING


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READING

&DISCUSSIO

N


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Surve

()at is rotor resistance control*

()at is t)e a!vanta+e o, rotor resistance control*

()at are t)e !ra-.ac/s o, rotor resistance control*


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)RAW

MIN)MAP


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S@MMARJ

MIN) MAP


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MIN) MAP

#0

StaticRotor

Resistance Control

Rotor Resistance Control

ConventionalRotor

ResistanceControl

Applications

Aratre core

Aratre -in!in+

Soot) an!Ste2less control

3ast res2onse Less 4aintenance


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4C56s

17 Rotor resistance control is e2loe! in

:a; cranes

:.; elevators

:c; -ar!


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7T)e a>or !isa!vanta+e o, rotor resistance control is

:a;lo- e,,icienc

:.;)i+) cost:c; lo- tor?e

:!; )i+) 2o-er ,actor


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#7T)e s2ee! o, an in!ction otor can .e controlle! .

sin+

:a;stator resistance control

:.;rotor resistance control

:c;2o-er ,actor control

:!;stator rotor control

Documents

PPT -2 ( Static Rotor Resistance Control)