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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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Constant Volts+/0 #V+f%Control
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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Constant Volts+/0 #V+f%Control
11
Vrated
frated
9inear o:set
Non2linear o:set . varies -ith Is,oost
Vsvs- frelation in Constant
Volts/$% drives
Vs
f
.inear osetcurve .for hi&h2startin&torque loadse*#loed 0or
*osta##lications
1on2linearoset curve .for lo2
startin+torque loads
,oost2 toco!pensate forvolta&e drop atRsand Lls
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Constant Volts+/0 #V+f%Control
"or operation at frequenc Kti!es rated frequenc1
fs; Kfs3rateds; Ks3rated #*%
#Note1 in #*% 3 speed is &iven as !echanicalspeed%
Stator volta&e1
#
%
The !a(i!u! torque is then &iven ,1
#?%
-here sand Vsare calculated fro! #*% and#
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Constant Volts+/0 #V+f%Control
1%
"ield Wea5enin& Mode #f7 frated%
Reduced 'u( #since Vsis
constant%
Torque reducesConstant Poer
3rea!above base s#eed"
ConstantTorque3rea
!belo bases#eed"
Rated #4ase%frequenc
Note1Operationrestricted,et-eensnchronousspeed and T!a(for
!otorin& and
,ra5in& re&ions3i$e$ in the linear
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Constant Volts+/0 #V+f%Control
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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Constant Volts+/0 #V+f%Control . Open2loop
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/$% Drive it4 Sli#Co*#ensation2 Slip speed is esti!ated and added to the referencespeed r
Note1 e; s; snchronous
speed
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Constant Volts+/0 #V+f%Control . Open2loop
I!ple!entation /o- is sl esti!ated in
the Slip Co!pensator
@sin& T2curve3 slTe
slcan ,e esti!ated ,esti!atin& torque-here1
#F%
#G%
1
O#en2loo# Constant Volts/$% 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