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4
LOAD COMMUTATED INVERTERFED
SYNCHRONOUS MOTOR DRIVE
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CONTENTS
ARTICLE PAGE NO
Certificate. ..ii
Ackn!"e#$e%ent .iii
A&'tract...i(
Cntent'....(
Li't f fi$)re' . ..(iii
G"''ar* f '*%&"'.+i
CHAPTER ,
INTRODUCTION
General introduction................................................................................1
LCI fed synchronous........................................................................3
1.3 Scope of the project.... .4
1.4 Organization of the report ..4
CHAPTER -
Literat)re ')r(e*.
CHAPTER /
LCI FED SYNCHRONOUS MOTOR DRIVE
3.1 Syste description.............................................................................. .!
3." #asic dri$e control....!
3.3 %&el$e pulse operation...1!
CHAPTER 0
MODELING THE LCI DRIVE
4.1 #asic LCI schee.."'
4." Ipleentation of the odel...."1
4.3 Si( pulse LCI dri$e ..."1
4.4 %&el$e pulse LCI dri$e..")
4.* siulation of LCI dri$e."+
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CHAPTER 1
SIMULATION RESULTS AND DISCUSSION
Si( pulse LCI dri$e operation................................................3'
Starting of si( pulse LCI dri$e..3*
,ual channel dri$e operation -&ith t&o otors...3!
Starting of dual channel dri$e -&ith t&o otors..41
,ual channel dri$e operation -si( phase achine44
Starting of si( phase achine....4+
CHAPTER
MODIFIED LCI DRIVE
).1 Introduction of the /odel......*1
)." Ipleentation of the /odel....*"
CHAPTER 2
SIMULATION RESULTS AND DISCUSSIONS OF MODIFIED LCI DRIVE
0.1 LCI dri$e operation..*)
LCI dri$e operation of La achine....)1
Starting of the LCI dri$e -La /achine..)4
CHAPTER 3
HARD4ARE IMPLEMENTATION OF THE MODIFIED LCI DRIVE
Introduction to the ,S2 controller...))
,escription of ard&are set up....)0
CHAPTER 5CONCLUSIONS AND SCOPE FOR FUTURE 4OR6 ...2,
REFERENCES...2-
APPENDICES
2256,I7
S25CI8IC%IO6S O8 %5 LCI ,9I:5S....03
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2256,I7 #
S;8
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S;8
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$iii
LIST OF FIGURES
Fi$)re De'cri7tin Pa$e
N. N.
1.1 Load coutated in$erter fed synchronous otor 3
3.1 detailed diagra of a single channel LCI 1'
3." 8iring se=uence of the thyristors 11
3.3 S&itching otor>in$erter current fro one leg to the ne(t 1"
3.4 2hasor diagra of a synchronous otor 13
3.* 8orced Coutation 8iring /ode 1*
3.) /otor :oltage and Current in the Self;Coutated /ode 10
3.0 1" pulse -" Channel LCI dri$e scheatic diagra 1+
4.1 %ypical scheatic of the LCI fed synchronous otor dri$e "'
4." /odel of the si( pulse LCI ,ri$e ""
4.3 ,etails of the controller "*
4.4 2I Speed controller ")
4.* 2I current controller ")
4.) %&o channel dri$e "!
4.0 Synchronous /achine of t&o channel dri$e "0
4.! %&o channel dri$e &ith si( phase /achine "+
*.1 Speed profile under the load and speed $ariation 31
*." 2rofile of the %or=ue de$eloped 31
*.3 Stator current profile 3"
*.4 #ac? 5/8 profile 3"
*.* ,c lin? $oltage profile 33
*.) Supply current profile 33
*.0 %, of input current 34
*.! Speed profile during starting of the achine 3*
*.+ %or=ue profile during starting 3)
*.1' #ac? 5/8 profile during starting 3)
*.11 #ac? 5/8 profile sho&ing the spi?es during coutation 30
*.1" /otor current profile 30
*.13 Speed profile of dual channel dri$e 3!*.14 %or=ue profile of dual channel dri$e 3+
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+
*.1* Input currents of t&o channels 3+
*.1) /otor stator currents for oth /achines 4'
*.10 Supply current profile 4'
*.1! %, analysis &indo& 41
*.1+ Speed profile during starting of ,ual channel LCI dri$e 41
*."' Speed profile of synchronous otor 4"
*."1 #ac? 5/8 profile during starting of ,ual channel dri$e 4"
*."" #ac? 5/8 sho&ing the spi?es 43
*."3 /achine stator current profile 43
*."4 Speed profile of Si( phase /achine 44
*."* %or=ue profile of Si( 2hase /achine 44
*.") Instantaneous tor=ue profile 4*
*."0 /otor stator current profile for oth &indings 4*
*."! /otor #ac? 5/8 profile for oth &indings 4)
*."+ Input current profile of oth channels 40
*.3' Supply current profile of the dri$e 4!
*.31 %, analysis &indo& 4!
*.3" Speed profile of Si( 2hase /achine during starting 4+
*.33 %or=ue profile of Si( 2hase /achine during starting 4+
*.34 #ac? 5/8 profile during starting of Si( 2hase /achine *'
).1 #loc? ,iagra of LCI fed Synchronous ,ri$e *1
)." #loc? ,iagra of LCI ,ri$e &ith chopper rectifier configuration *1
).3 /odel of rectifier chopper ased LCI dri$e *4
).4 Controller loc? diagra *4
).* 2I Speed controller **
).) 2I current controller **
0.1 Speed profile under the load and speed $ariation *0
0." Instantaneous tor=ue profile *0
0.3 #ac? 5/8 profile of the /achine *!
0.4 Stator current profile *!
0.* Supply current profile *+
0.) %, of supply current )'
0.0 Speed profile under the load and speed $ariation )1
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0.! Stator current profile )"
0.+ #ac? 5/8 profile of the /achine )"
0.1' Supply current profile )3
0.11 %, analysis of supply current )3
0.1" Speed profile during starting )4
0.13 In$erter pulses during stating )4
!.1 Outline diagra of hard&are set up ))
!." Sensor circuit diagra )+
!.3 Optocoupler and isolation circuit )+
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GLOSSARY OF SYM8OLS
C lternating current
,C ,irect current
I, Induced draft
8, 8orced draft
CSI Current source in$erter
LCI Load Coutated In$erter
2 6uer of poles
pu per unit
@ /oent of inertia in ?g>"2I 2roportional Integral
wb #ase speed in radian per second
wr 9otor speed in radian per second
wbm #ase echanical speed in radian per second
%hyristor firing angle
Coutation lead angle
Coutation o$erlap angle
A /argin angle
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CHAPTER ,
INTRODUCTION
GENERAL
5$er since the industrial re$olution and in$ention of the electricityB otors ha$e
een the &or?horses of odern industries. Se$enty percent of the otors used in the
industry are C induction otors. %hese otors suffered fro the fact that speed
control &as not easy in these achines. 8or critical applications re=uiring precise
speed and tor=ue control re=uireentsB the industry relied on the ,C otors for
years. %he ,C otors suffer fro cople( design and increased aintenance cost
due to the increased &ear and tear of the coutator and rushes etc.
fter the appearance of the electronics in the last century and the de$elopent of
coponents li?e transistors and thyristorsB the industry gradually igrated to
&idespread use of djustale Speed ,ri$es -S,B resulting fro the association of
electrical otors and po&er electronics con$erters 1;3D. #ecause of its sipler
controlB the first S,s &ere ased on rush ,C otorsB ut after the ad$ent of
icroprocessors and ne& control algorithsB such as $ector control and direct
tor=ue controlB the continuing trend &as to&ards the ore roust C otors. fter
the oil crisis and the en$ironental proles faced y the &orldB the S,s ha$e
ecoe e$en ore attracti$e due to the energy sa$ings that could e otained y
a?ing use of odern control techni=ues.
5lectric ,ri$es technology is no& strong and atureB co$ering ranges fro fe&
Eatts to tens of /ega&atts. In the high po&er rangeB for applications li?e
copressorsB fansB pups and electric tractionB Load Coutated In$erter -LCI
fed &ound field synchronous otor is coonly used. LCI functions on the natural
coutation of thyristors. In order to reduce the haronics injected oth in the
net&or? and in the otor and to iniize the tor=ue pulsations and lossesB it is
norally used in a t&el$e;pulse $ersion.
Synchronous otors are eployed in these dri$es as these ha$e a higher full load
efficiency and po&er factor than induction otors of coparale rating. Eound
field synchronous otors can e designed for a higher po&er rating than induction
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otors. Since the air gap flu( is not produced solely y the agnetizing current
dra&n fro the aratureB a larger air gap suiting the echanical design can e
chosen.
igh efficiency and controllale po&er factor are the ad$antages offered y the
synchronous otor &hich offset the higher initial cost of the synchronous otors in
the ega&att range applications. Such otors &hen used in conjunction &ith the
current source in$erter are est suited for copressors and fan loads. In the po&er
generation industryB such dri$es find use in the 8orced ,raft -8, fansB Induced
,raft -I, fansB lo&ersB air copressors for the pneuatic control de$ices and
transportation of ash in the dry ash handling systes etc.
%husB the synchronous otor presents an e(cellent alternati$e to the induction
otor in the high po&er and $ariale speed applications. o&e$erB one of the ajor
disad$antages of the synchronous otor is that it is not self;starting. #ut &e can
use LCI as soft starters .It re=uires ore aintenance and it is costlier than an
induction otor of siilar rating.
Speed of the synchronous otor is directly proportional to fre=uency and can e
controlled y $arying the fre=uency. :ariale fre=uency control can e done in t&o
odesF -a true synchronous ode or - self;controlled or self;synchronous ode.
In true synchronous odeB stator supply fre=uency is gradually changed fro an
initial $alue to the re=uired $alue so that the difference et&een the synchronous
speed and rotor speed is sall. %he rotor can thus trac? changes in the synchronous
speed. Ehen the desired synchronous speed is reached the rotor pulls into step after
hunting oscillations.
In self;control odeB as the rotor speed changesB stator supply fre=uency is changed
proportionally to a?e the synchronous speed sae as the rotor speed. ence rotor
runs at synchronous speed for all operating points thus eliinating hunting
oscillations.
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SELF CONTROLLED LOAD COMMUTATED INVERTER 9LCI: FED
SYNCHRONOUS MOTOR ;,
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SCOPE OF THE PRO>ECT
LCI synchronous otor dri$es are coercially a$ailale fro reputed
anufacturers for alost "' years no&. %hese are norally a$ailale in oth si(
pulse and t&el$e pulse configuration. In the latterB a otor &ith t&o sets of
&indings is used. %he &indings are positioned 3' electrical degrees apart in space.
%he oject of this project is to de$elop a odel of the load coutated in$erter fed
synchronous otor dri$e for oth si( pulse and t&el$e pulse configuration using
/%L# > SI/ SI/
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and its odeling. Chapter 7 e(plains aout the siulation results and discussions of
the odified LCI fed dri$e. Chapter 8 e(plains aout the hard&are ipleentation
of the project. Chapter 9 gi$es the conclusions and scope for future &or? to e
carried out in this direction.
Appendix A gi$es the coplete specifications of the LCI dri$e installed at 6%2C
,,9I and 6%2C LGO6 and the achine in the 2G /CI65S la
Appendix B gi$es the $arious S functions used for the coutation and firing of
the load coutated in$erter and other /%L# progra listings.
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CHAPTER -
LITERATURE SURVEY
%he pre$ious chapter presented the ojecti$es of the project &or? as de$eloping a
odel for LCI fed synchronous otor dri$e in oth si( pulse and t&el$e pulse
configurationsB &hich are coercially a$ailale fro $arious anufacturers
and to study the perforance under $arious operating conditions.
,e$elopent of the odel in$ol$es understanding the concepts of the
synchronous otorsB the po&er electronic con$ertersB LCI dri$esB the $arious
systes and susystes of the coercially a$ailale e=uipents etc. Operation
of such dri$es at lo& speed &ith a large load tor=ue poses a great challenge. %he
a$ailale literature on the LCI fed synchronous otor dri$e has een studied for
coprehending the functioning of the dri$e unit.
G ,ueyHs 1D oo? titled J2o&er seiconductor controlled C ,ri$esK is a
standard reference oo? for understanding the principles of operation of the
odern C ,ri$es.
#ial #ose"D in his oo? titled J2o&er electronics and C dri$esK descries
the asic principles of the po&er seiconductor de$icesB C achines B $oltage
fed and current fed in$erters and control of synchronous achines in a $ery
concise anner.
8inney 3D in his oo? titled J:ariale 8re=uency C ,ri$e SystesK has
e(plained the operation of the si( pulse current source in$erter fed otors in a
$ery siple and easy to understand anner.
Operation and aintenance anualsB dra&ings and other reference aterial of
General 5lectric LCI dri$es 4D ha$e een studied in detail. ,atasheets of the
$arious coponents and systes ha$e een referred to.
oang Lehuy *D in his paper on J/odeling and siulation of electrical dri$es
using /%L#>SI/SI/
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/anoj #arsaiyan !D in his / %ech dissertation has e(plained the concepts of the
synchronous otors and the application of the ,%C to high capacity synchronous
otor dri$es and LCI control.
lcaso and Cardoso +D in their paper J/odeling and siulation of LCI dri$e
systes under noral and faulty operate conditionsK ha$e e(plained the
operational principles of the t&el$e pulse dri$es $ery &ell.
Schiferl and Ong 1'D in their paper JSi( phase synchronous achine &ith C
and ,C stator connections 2art IF e=ui$alent circuit representation and steady;
state analysisKB ha$e gi$en the concepts of the si( phase synchronous achines.
/%L# reference 11D anuals are $ery helpful for odeling in the dri$e.
@.;@. Siond B . Sapin B /. %u 7uanB 9. EetterB 2. #ureister1"D paper J1";
2ulse LCI synchronous dri$e for a "' /E copressor odelingB siulation and
easureents ga$e industrial e(posure to the LCI dri$e
#hi Singh, Sanjeev Singh and S. P. Hemanth Chender [13]paper Jaronics
/itigation in LCI;8ed Synchronous /otor ,ri$esK and #. SinghB Sanjee$
SinghBand S.2. eanth Chender14D paper K 2o&er =uality ipro$eent in load
coutated in$erter;fed synchronous otor dri$esK ga$e the e(posure to the
$arious po&er =uality ipro$eent techni=ues
#hi SinghB Sanjee$ Singh1*D paper Kpo&er =uality ipro$eent using
optiized passi$e filter for 1";pulse rectifier chopper in LCI fed synchronous
achineK is the one y &hich de$eloped the odel of rectifier chopper ased
LCI dri$e and ade an attept for ipleenting ard&are of the sae odel
it uar @ain and V. T. Ranganathan[16]paper, Jyrid LCI>:SI 2o&er
CircuitL
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CHAPTER /
LOAD COMMUTATED INVERTER FED
SYNCHRONOUS MOTOR DRIVE
%he last chapter discussed aout $arious research papersB te(too?sB standards and
anuals rele$ant to this project &or?. %he principle of operation of the Load
coutated In$erter fed synchronous otor dri$e is presented in this chapter.
%ypical details of the LCI ,ri$e installed at 6%2C ,adri are also discussed.
In $ie& of the syste reliaility and potential po&er sa$ings in the Induced ,raft
fansB the LCI fed synchronous otor dri$e is eing chosen for these fans. So farB
con$entional Induction otors and hydraulic couplings ha$e norally een used for
this applicationB though these ha$e een $ery costly.
SYSTEM DESCRIPTION
%he asic loc? diagra of the LCI dri$e has already een presented in 8ig. 1.1. It
has a lineside con$erter fed y a *' z three phase supply feeding the otor side
con$erter &hich con$erts its input ,C to $ariale fre=uency C supply. %he
follo&ing sections gi$e the asics of the LCI dri$e operation.
8ASIC DRIVE CONTROL
%he Load Coutated In$erter -LCI is a staticB adjustale fre=uency dri$e syste
&hich controls a synchronous otor fro near zero to rated speed 3D. %he asic
syste consists of a line coutatedB phase controlled thyristor con$erter &hich
feeds a load coutated thyristor con$erter through a dc lin? reactor.
%he transforer pro$ides isolation fro the ac syste us and pro$ides the correct
$oltage at the terinals of the rectifier. lsoB the internal ipedance of the
transforer liits the agnitude of any do&nstrea us faults. %he rectifier is a
thyristor ridge &hose gating is controlled to produce a $ariale dc $oltage at its
output. %he output of the rectifier is fed through the dc lin? reactorB &hose function
is to a?e the current ripple;free and to ?eep it continuous o$er the coplete
operating range of the syste.
!
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%he dc lin? reactor output is then fed into the in$erter ridge &hich produces
$ariale fre=uency ac at the stator terinals of the synchronous otor. %he in$erter
ridge and the rectifier ridge use the sae po&er hard&are and are controlled y
icroprocessor;ased electronics. lthough the ridges are laelled MrectifierM and
Min$erterM it is possile for the re$ersal of their roles and hence po&er flo& can
re$erse. In this case the otor &ould e ra?ed y puping its energy ac? into the
ac line. ore general noenclature is to call the line side ridge the source
con$erterB and to call the otor side ridge the load con$erter.
%he synchronous otor field is usually e(cited y a rushless e(citer coupled to the
otor shaft. %he rushless e(citer is a &ound rotor induction achine &hose rotor
$oltage is rectified y rotating diodes to supply the necessary field current to the
synchronous otor. %he e(citer stator is connected to au(iliary C supply. Its rotor
$oltage and thus the synchronous otor field e(citation $aries &ith otor speed 4D.
ore detailed diagra of a single channel LCI is sho&n in 8igure 3.1.
s sho&n in this figureB the electronic control recei$es the follo&ing signal inputsF
1. ttenuated line and load us $oltage signals.
". ttenuated line and load current signals fro current transforers.
3. Speed reference signal.
4. 2rocess coands such as stopB startB etc.
+
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8ig 3.1 detailed diagra of a single channel LCI dri$e 4D
%he attenuated us $oltage signals are used y the control to synchronize thyristor
firing &ith the line and load $oltagesB to pro$ide $oltage sensing across the thyristor
cellsB and to pro$ide electronic o$er>under $oltage detection. %he attenuated current
signals are used for regulator current feedac?B electronic o$ercurrent detectionB and
soft&are;ipleented fault detection.
%he electronic control e$aluates the process coands and internal status signals to
deterine &hether the dri$e should e in a stoppedB startedB alaredB or faulty
condition. If in a started conditionB the electronics pro$ides gate signals to control
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the thyristor ridges. %hese signals are lo& le$el and are conditioned in the po&er
ridge circuitry to pro$ide the necessary isolation and po&er le$el.
%he po&er ridges are of the si( pulseB doule &ay type and the %hyristor #ridge
legs MfireM in the order that they are nuered in 8igure 3.1 and as sho&n in 8igure
3.".
8ig 3." 8iring se=uence of the thyristors 4D
%he source con$erter current is successfully transferred fro one leg to the ne(t y
the ac line $oltages. SiilarlyB the in$erter current is successfully transferred y the
otor stator $oltages.
%he process of s&itching otor>in$erter current fro one leg to the ne(t is
illustrated in 8igure 3.3.
%he principles illustrated here apply to a rectifier ridge as &ell as to an in$erter
ridge. %his phase;controlled s&itching is accoplished y using the follo&ing t&o
thyristor characteristicsF -1 &hen the $oltage across the thyristor is positi$eB it can
e triggered into conductionB and -" it &ill not perit current flo& in the re$erse
direction. %husB in an alternating $oltage circuitB thyristor conduction &ill cease and
re$erse $oltage &ill egin to appear &hen the current ecoes zero. Current transfer
ust e copleted efore $oltage cross;o$erB &ith a argin angle.
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8ig 3.3 S&itching of otor>in$erter current fro one leg to the ne(t 4D
%his angle ust e long enough to allo& the pre$iously conducting leg thyristors to
reco$er to their loc?ing state efore re$erse $oltage is applied. %his is &hy the
fundaental coponent of current ust lead the $oltageB fro an in$erter>otor
$ie&point. 8ro the rectifier>source $ie&pointB the fundaental coponent of
current &ill al&ays lag the $oltageN ut for successful coutationB the angle 1!'P
;Q 1!'P;R; A ust al&ays e less than 1!'PB a practical liit is 1**P. Q is called
the coutation lead angleB A is the argin angle and R is the o$erlap angle of the
load side con$erter. Q 1!' TB &here T is the firing angle of the achine side
con$erter. CorrespondinglyB a practical iniu $alue for A for the in$erter ridge
is "*P. %he otor po&er;factor angle is al&ays less thanB ut cannot ecoe zero.
%he LCI control syste ust confor to the characteristics of the synchronous
otor operating at leading po&er factor. phasor diagra for a synchronous
achine operating at leading po&er factor is sho&n in 8igure 3.4.
1"
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8ig 3.4 2hasor diagra of a synchronous otor 4D
%he otor $oltage characteristic is ainly a function of the rotor field;e(citationB
5fB and the de;agnetizing action of direct;a(is current &hich produces the I,7,
$oltage in opposition to the $oltage produced y field e(citation.
n increase in stator current &ill result in higher direct;a(is currentB &hich &ill
increase I,7,B &hich in turn decreases the achine $oltage :t a$ailale for
coutationB therey increasing displaceent angle UB &hich further increases
stator currentB etc. until e=uiliriu is reached at a ne& operating point.
Ehen operating in any ode the electronic control ust synchronize firing of the
source and load con$erters to the ac line and otor us $oltagesB respecti$ely. %he
priary feedac? for accoplishing this is the attenuated us;to;ground signals for
oth con$erters. ttenuated us;to;ground $oltages are rought into the electronic
control and coined to produce line;to;line analogs for oth con$erters. %hese
line;to;line $oltages are then integrated to otain flu( signals. %he zero crossings of
these signals are used in the synchronization of the phase loc?ed loop for the firing
control of oth source and load con$erters. t lo& speedB efore the phase loc?ed
loop is effecti$e on the load sideB the zero crossing ar?s are used as a tiing
reference for firing the ne(t incoing thyristor.
%he source side con$erter for the LCI al&ays operates line;coutatedN i.e.B the ac
line pro$ides the eans for transferring conduction fro one thyristor to the ne(t.
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%he load side con$erter ay operate either load -self coutated or force;
coutatedB depending on otor speed and flu( le$el.
s the synchronous otor rotor -field rotatesB the near;sinusoidal shaped field flu(
cuts the stator &indings to produce a set of three sinusoidal $oltages in the stator
&hich are angularly displaced y 1"' electrical degrees. %he agnitude of this
counter ef is proportional to speed and field strength. t lo& speeds the induced
counter ef is insufficient to coutate the thyristors in the load side con$erter. In
this odeB the control ust operate in a forced coutated ode.
%here are t&o forced coutated odesF fi(ed fre=uency firing and segent firing
odes. In fi(ed fre=uency operationB the load con$erter is fired at a fi(ed lo&fre=uency. %his fre=uency is adjustale and optiized at startup for est operation.
%his ode is used to start the otor and otain a speed &ith sufficient counter ef
to allo& the control to loc? on to it.
Ehen in forced coutationB conduction of the load con$erter is stopped y
pushing the firing angle of the source con$erter to in$ersion liit until the dc lin?
-reactor current is zero as sho&n in 8igure 3.). %hus the dc lin? current appears
chopped into )';degree;&ide segents of otor fre=uency -angle. Ehen fi(ed
fre=uency ode is egunB the otor ay initially o$e ac?&ard unless the control
is specifically prograed to pre$ent re$erse rotation &hen starting.
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8ig. 3.* 8orced Coutation 8iring /ode 4D
If the field is o$ing ac?&ards efore startingB the control &ill stop the field
-rotor and accelerate it in the desired direction.
s soon as the control detects sufficient alance and le$el of the stator flu( &a$esB it
transitions to segent firing ode. t this pointB the $oltages present at the output
of the otor $oltage integrators -flu( are sufficient to allo& the control to
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synchronize load thyristor firings to the otor $oltage. %he control copensates for
the iperfect integration at lo& fre=uency and fires the load thyristors to operate the
otor at near unity po&er factor.
In the segent firing odeB current and load coutation is still controlled y
source thyristor ridge shutoffB ut no& thyristor firings are synchronized to the
otor counter ef.
Segent firing ode continues until the otor has reached appro(iately 1' of
rated speedB &here the synchronous otor counter ef is sufficient to coutate
the load side con$erter. t this pointB the control transitions to load coutated
operation.
In the self coutated odeB &hich is the principal operating odeB the otor ust
e operated at a leading po&er factor in order to e ale to ensure coutation of
the load con$erter. %he electronic control acts to ?eep the otor po&er factorB and
therefore tor=ue per apereB as high as possile. %his is accoplished y firing the
load con$erter as close to in$ersion liit as possile &hile aintaining sufficient
argin for successful coutation of current fro one de$ice to the ne(t. %he
coutation tie re=uired is a function of otor currentB otor -coutating
inductanceB and the $oltage difference et&een the lines in$ol$ed in the attepted
coutation. 8or a gi$en load current and otor inductanceB a corresponding
aount of $olt;seconds is re=uired for successful coutation. %he control reads
the pea? $olt;seconds of the integrated line;to;line otor $oltages and the otor
current. %he otor coutating inductance is a constant stored in the
icroprocessor syste eory.
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are teporarily connected y the thyristor legsB is practically zero during
coutationN the line;to;line $oltage is only the for&ard $oltage drops of the
conducting thyristor legs.
t high load on the otorB the apparent po&er factor MseenM y the po&er source
increases. %his is ecause the source con$erter firing ad$ances -is reduced to otain
ore current. %he haronics in the current and the resultant haronics in the
$oltageB due to coutation MnotchingMB &ill decrease.
%he fundaental control strategy is to increase otor current in response to a load
tor=ue increaseN the dc lin? $oltage is increasedB therey raising otor current so as
to ?eep the otor speed constant.
T4ELVE@PULSE OPERATION ;0=
%&el$e;pulse operation is li?e t&o identicalB separateB si(;pulse dri$es operating
fro a coon source at the sae current and firing angleB &ith the firing reference
angles shifted y 3'V using the isolating transforers. %he t&o otors are coined
into one frae. %his reduces the otor costB including installationB and reduces the
tor=ue pulsation aplitude &hile raising the tor=ue pulsation fre=uency. %his is
achie$ed y separating the stator &inding into t&o identical &indingsB ut isolated
and phase;shifted y 3'V. %his constructionB utilizing a coon agnetic fraeB
including a coon fieldB causes the load;side con$erter $oltage to e e=ual in
aplitude and fre=uencyB et&een the t&o dri$e channels. %he transforer design
a?es the source;side con$erter $oltage e=ualB ut also 3'V apart et&een the t&o
channels. It is not necessary that source;side and load;side $oltages e phase;
shifted. %he otor &indings are shifted to otain soother tor=ue for e=ual current.%he transforer &indings are shifted to reduce the haronic distortion on the po&er
syste and to raise the haronic fre=uencies. %ypical connections of t&el$e pulse
LCI dri$e is sho&n in 8igure 3.0
Inter;channel counication allo&s one channel to e the aster and the other the
sla$eB &hich ta?es its tor=ue reference fro the aster. %his counication allo&s
the t&o otor &inding currents to e alanced. %hus the channels deli$er e=ual
po&erB ta?e e=ual currentB and fire at the sae relati$e firing angle. %his utilizes the
1!
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motor and drives capabilities to the best extent and also minimizes the harmodistortion on the power system, as the frst two harmonics present i each six-
c annel cancel (5th and 7th harmonics). ther hi!her-order harmonicspresent, but their amplitudes are m ch smaller.
will be
"i! #.7 $welve pulse (% &hannel)&' drive schematic di !ram *
+ twelve-pulse system also has the capability o shuttin! downne channel
aintenance &hile the otor continues to run on the other channel -&ith reduced
tor=ue and usually reduced speed range. Ehen the out;of;ser$ice channel is ready
for operationB it ay e returned to ser$ice &ithout interr pting the dri$e syste.
%his chapterpresented the asic principles f operation of the LCI synchronous
otor dri$es. ,etails of the control strategyof the coercial dri$es &ere also
discussed. %he ne(t chapter &ill present the odeling aspects.
1+
L a
o
u
o
h
u
n p
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CHAPTER 0
MODELING THE LCI DRIVE
In the present chapter the odels of the LCI synchronous otors de$eloped using
the /%L#> SI/
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IMPLEMENTATION OF THE MODEL IN MATLA8SIMULIN6
%he odeling in the /%L# > SI/ SI/
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&ontinuous
abc+
'abc
a
b
&c
/ v-
!
/
+
-
&
/ i-abc
+'abc
a
b&c
input voltage
V-I M
[Vabc]
input current
dc voltage
DC LINK INDUCTOR
dc lin current
DC LINK
M!"#
[dclin] LO"D #ID! INV!RT!R
g
$
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%
-
C
&otor current
Voltage
'Rotor (peed
'Rotor &ec)an
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%
C
powergui
CONTROLL!R
LCI ,ri$e
[,][t)eta]
#peed reerence
[Vabc] [dclin]
Vin
"n
g
le
8ig. 4." /odel of the si( pulse
#o
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rc
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.
#
p
eed
DC
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in
Load
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p
eed
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e-
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%he three input terinals are connected to the transforer loc? output. %he
fourth input terinal is for the firing pulses for the control.
i$ DC "ink ReactrF %his inductor acts as a filter to sooth out the ,C lin?
current and to allo& the t&o con$erters to operate independent of each other.
$ La# 'i#e In(erterF Input to this loc? is ,C $oltage fro the source side
con$erter and firing pulses. 8iring pulses to this loc? is gi$en through an S;
functionB &hich changes the firing se=uence ased on rotor position. Output of
this loc? is 3 phase currentsB &hich flo& through the achine.
(i: S*ncrn)' Mtr &"ckF %his loc? has een created using the
synchronous achine odel a$ailale in Si2o&erSystes -2o&er Syste
#loc?set in per unit configuration and the achine easureents deu(. %he
achine paraeters are defined in per unit representation. Input to the arature
coes fro load;side Con$erter #ridge. 8ield $oltage and Load tor=ue are to e
gi$en as inputs. Outputs fro this loc? are $arious =uantities that can e
easured fro the achine such as speedB electroagnetic tor=ueB flu( lin?agesB
currents and po&er. %his loc? has een created for oth single &inding and
doule &inding synchronous otor.
$ii Cntr""erF Controller is the heart of the LCI dri$e as this is the unit &hich
controls the firing of the source and load side thyristor ridges through the
feedac? signals of the speed current $oltage etc. /odel for the Controller
de$eloped for the LCI dri$e is sho&n in 8igure 4.3. %he ain susystes of the
controller are e(plained elo&.
a Voltage signals: the $oltage signals are deri$ed fro the source to
synchronize the firing of the source %hyristor #ridge &ith the supply
$oltage fre=uency.
Synhroni!ed p"lse generator: Source side con$erter firing is controlled
through a synchronized );pulse generator. Input to this loc? are the three
phase line;to;line $oltage signal and con$erter firing angle. 2ulses
generated through pulse generator at po&er fre=uency are passed on to the
thyristor con$erter. o&e$er upto 1' of the rated speed of the otorB the
source thyristors ust e force coutated to a?e the ,C lin? current
zero. %his is achie$ed through the firing angle controller and passing the
"3
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output of oth the susystes through an 6, loc?. #eyond 1' of
rated speedB the source thyristors are line coutated.
c #iring angle ontrol: %his susyste has een de$eloped using S;
8unction. It senses the rotor speedB ,C lin? current and the rotor
position to decide &hether the syste shall e operated in the fi(ed
firing ode or the self coutated ode.
d $% ontrollers: 2I controllers are used to generate the reference ,C
lin?current $alue -&hich is an inde( of the tor=ue re=uireent y
generating the error signal y coparing the reference and actual
speed of the otor. %his speed error is also needed to control the
closing of the circuit rea?ers of the other channel &hen the dri$e is
operated in the t&el$e pulse ode. 8urther the ,C lin? reference
signal output fro the first 2I controller -speed controller is
copared &ith the actual ,C lin? current $alue y the second 2I
controller -current controller to arri$e at the $alue of the source side
con$erter;firing angle -T. %he t&o 2I controllers are sho&n in 8igure
4.) and 8igure 4.0.
"4
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0& 1'23
4$4$ "6 8 &
alpha9de! +&pulses &+loc:
;
wm
o8>>0utput &466>2$
fxedfrin!
?in
m
+n!le
ulse =enerator ?8ource ulses
#0& 1in: %
8peed
"irin! +n!le &ontrol
846&> 8'0> &2$ 61
-3-
58peed 6e
8-"unction?
.# 0etails erspeed controller current control ler
%1oad ulses
LO"D #ID! CONT ROL
DETAILS OF THE CONTROLLER MODULE
8ig. of the controll
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")
8ig 4.4 2I Speed controller
8ig 4.* 2I Current Controller
T4ELVE PULSE 9DUAL CHANNEL: LCI DRIVE
Ipleentation of the si( pulse LCI dri$e is rather straightfor&ard as standard loc?s
for ost of the coponents are a$ailale.
%he t&el$e pulse operation of the dri$e is rather cople( as the t&o sets of &indings
are placed in the sae stator core &ith 3'V space shift. It has ipleented in t&o
&ays.
1 Eith t&o independent otors rotors coupled
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+dd?
?
m
m
m+
?+? %?
?
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?
%.?
m
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w
&ontinuous power!ui
v* ,dclin* t)eta *//01
'Rot)toert
&a ecCONTROLL!R2
'!lectro&
m
PmA
Mea(ure&ent(2
V-I M*
Vabc
"
Iabc
%
dclin*
g
+A
i$
DC LINK INDUCTOR2- g
$ +A
Mea(ure&ent(*
v*
3ro&2V-I M2
Vabc"
a2Iabc A
.&(tep
B
C
X
Vf_ Y
b B
C -
c C
v2 ,
dclin2
B-
C
t)eta*//01
a % b2
b c2
c C
Ba3
b3
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B
C
Network
V (tepZ c3
C24Vrm! "" - # $VA
%i& P'a!e
%()c'ro)ou! $ac'i)e
24V #*VA
CONTROLL!R*
Mea(ure&ent(4 v2
24 V 24 V
#, *VA
Mea(ure&ent(5 V-I M6
Vabc"
dclin2i
g -+
DC LINK INDUCTOR*
g$
+
V-I M5
Vabc"
Iabc
Iabc
a
b
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% B-
C
" a %
% b
- CcC
cC
8igure 4.! %&o channel dri$e &ith si( phase achine
SIMULATION OF THE LCI DRIVE MODEL
t the start of the siulationB po&er supply is applied to channel 1-/aster. %he
po&er supply to the other cannel is controlled through circuit rea?ers &hich close
only &hen the speed error of the first channel is zero. %he speed of the achine no&
increases to the final $alue due to the contriution of the t&o channels.
Coplete specifications of the t&o LCI dri$es; one installed at 6%2C ,adri and the
other for 6%2C ahalgaon are gi$en in appendi( . %his chapter dealt &ith the
siulation odels of LCI fed synchronous otor dri$e ipleented in the /%L#
> SI/
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CHAPTER 1
SIMULATION RESULTS AND DISCUSSION
In the pre$ious chapter /%L#>SI/
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%ie in seconds
8igure *.1 Speed profile under the load and speed $ariation
%ie in seconds
8igure *." 2rofile of tor=ue de$eloped
In this tor=ue profile &e can see the $ariation according to the load and speed
$ariation coands. %he and is the ripple in the actual de$eloped tor=ue.
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8igure *.3 Stator current profile
%ie in seconds
In the ao$e profile &e can clearly see the coutation o$erlap of the currents due to
the otor inductance. %he o$erlap $aries &ith the load conditions also.
%ie in seconds
8igure *.4 #ac? 5/8 profile of the achine
%he current o$erlap &ill e hea$y &ith loaded conditions than lightly loaded
conditions as current is lo& &ith light loads and hence inductance stored energy is
liited.
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8igure *.* ,C lin? $oltage%ie in seconds
8igure *.) Supply current profile
%ie in seconds
Eith the ad$ent of po&er electronic de$ices &e ha$e lot of ad$antages li?e good
control on achinesB energy con$ersion and non;rene&ale energy sources. long
&ith these ao$e ad$antages &e ha$e the ig prole of po&er =uality due to
s&itching .the sae prole effects LCI dri$e fed synchronous achine. One of the
paraeter &hich indicates the po&er =uality inde( is %, -total haronic distortion.
8igure *.0 sho&s the %, of the input current of the dri$e eing "+.+*.
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8igure *.0 %, of input current
%he controller used consists of 2I controllers here &e ha$e the prole of steady state
error &hich can e noted fro the speed profile -8igure *.1. In the tor=ue profile
-figure *." &ith sudden decrease of speed at rated load the tor=ue has increased ore
than rated for attaining load &hich can &e get a clear picture fro profile. In the ac?
5/8 profile -8igure *.4. Ee are ale to see the $oltage notches during the s&itchinginstants of otor side con$erter. Eith supply current profile -8igure *.) &e are ale
to see it as it is =uasi s=uare &a$e in nature &ith high %, around 3'.
STARTING OF SIB PULSE LCI DRIVE
LCI dri$e also has an application of soft starters for large gas turines. Starting of
the otor fro rest is achie$ed y s&itching the current into the otor &indings so
that interaction et&een this current and the otor field flu( &ill cause the correct
direction of tor=ue to e de$eloped so that otor terns in the re=uired direction. %his
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3*
concept is already &ell e(plained pre$iously. %he speed $ariation for the otor can e
chec?ed in the 8igure *.!
%ie in seconds
8igure *.! Speed profile during starting
Ee can see the $ariations $ery high during lo&er speed as &e loo? for the a(iu
tor=ue coinations &e coutate the thyristor y a?ing the ,C lin? current zero
and s&itching other coination of thyristors.
%ie in seconds
8igure *.+ %or=ue profile during starting
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%he increase in tor=ue profile at 4.* seconds is due to load on the otor.
%ie in seconds
8igure *.1' #ac? 5/8 profile during starting
In the ao$e profile &e can see the increase in $oltage as speed is uilding up of the
otor and in ne(t figure i.e.B in figure *.11 &e can see the shape of the ac? ef.
%ie in seconds
8igure *.11 #ac? 5/8 profile sho&ing the spi?es during coutation
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%ie in seconds
8igure *.1" /otor current profile
%he achine started fro zero speed and up to 1' of the speed there &ill e
soe inner loop &hich ta?es care of gi$ing the pulses of the currents to de$elop the
a(iu tor=ue at all the instants. Ee can see fro speed profile -8igure *.!
$ariations up to 1' of the speed and after&ards it trac?s the coand of the speed.
8ro the tor=ue profile -8igure *.+ also &e can see the tor=ue pulsations of $ery high
in nature during the speed range fro ' to 1'. s &e ?no& the ac? 5/8 depends
upon speed as &ell as e(citation. s it is at rated e(citation the 5/8 increases
proportionality &ith speed. %he shape of the ac? 5/8 -8igure *.11 is fully &ith
$oltage notches due to s&itching. Eith current profile -8igure *.1" initially it dra&s
ore current and as speed pic?s up the no load currents fre=uency increases and
agnitude decreases.
,
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at 1.* seconds fro 1 p.u. then load is increased to 1.) p.u &ith speed at '.+* p.u .the
speed $ariation can e seen in 8igure *.13
%ie in seconds
8igure *.13 Speed profile
%ie in seconds
8igure *.14 %or=ue profile
%he elo& profiles are of input currents for star and delta channels. Ee can oser$e
the phase difference in the currents
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%ie in seconds
8igure *.1* Input currents of t&o channels
%he follo&ing profile of 8igure *.1) sho&s the supply current is &hich the
coination of star and delta current in &hich the doinant haronics of 3rd
and *th
order nullifies and %, decreases as sho&n in 8igure *.1)
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%ie in seconds
8igure *.1) /otor stator currents for oth achines
%ie in seconds
8igure *.10 Supply current profile
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8igure *.1! %, analysis &indo&
STARTING OF DUAL CHANNEL DRIVE
s though dual channel ut dri$e starts &ith single channel up to
particular speed and then oth channels ta?en into ser$ice speed raise up to rated
speed &e can see the speed $ariation in 8igure *.1+
%ie in seconds
8igure *.1+ Speed profile during starting of dual channel LCI dri$e
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%ie in seconds
8igure *."' %or=ue profile during starting of dual channel LCI fed dri$e
%he follo&ing 8igure -*."1 gi$es the picture of increasing ac? 5/8 during the
speed uilt up of the otor
%ie in seconds
8igure *."1 #ac? 5/8 profile during starting of dual channel LCI dri$e
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43
%ie in seconds
8igure *."" #ac? 5/8 sho&ing the spi?es
%ie in seconds
8igure *."3 /otor stator current profile
In the ao$e figure as speed increases the fre=uency increase and
current agnitude decreases
DUAL CHANNEL OPERATION 9SIB PHASE MOTOR:
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In this section the siulation results for the si( phase achine for
load $ariations ha$e een included. Initially the otor &as started &ith 3' load and
then &e increased the load at '." second to 1''. Ee can see the speed $ariation of
the achine in the follo&ing figure -8igure *."4
%ie in seconds
8igure *."4 Speed profile of si( phase achine
Ee can see the tor=ue profile for the entire siulation period in figure *."* sho&n
elo& and &e $ie& of the instantaneous tor=ue can e seen in figure *.")
%ie in seconds
8igure *."* %or=ue profile
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%ie in seconds
8igure *.") Instantaneous tor=ue profile
%ie in seconds
8igure *."0 /otor stator current profile for oth set of &indings
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In the ao$e profile &e can see there is no phase shift et&een the
current dra&n y the oth set of otor &indings as the otor &indings are all ready
3''
phase shifted. Eith coparison to pre$ious odel of rotor coupled doule
channel these currents do not ha$e of phase shift and it leads to less pulsations in the
tor=ue de$eloped and increase in agnitude also. It can e noted that there should e
soe echanis to e=ualize the currents so that load &ill e shared e=ually. In the
ao$e profile there is slight isatch and one channel is al&ays attending for slight
$ariations in the speed trac?ing. Eith the ao$e said echanis &e can coe out of
the prole of sharing.
%ie in seconds
8igure *."! /otor stator ac? 5/8 for oth set of &indings
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40
In the ao$e figure -8igure *."! &e can see the $oltage notches due
to the current coutation and these are ore copared to pre$ious doule channel.
%hese can e reduced to acceptale liits through proper design of the coponents
li?e inductor as &ell as input transforer. %he pre$ious case of transforer is
designed for the dri$e e=uipent &hich is installed at the 6%2C station
%ie in seconds8igure *."+ Input current profiles of the t&o channels
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%ie in seconds
8igure *.3' Supply current profile of the achine
8igure *.31 %, analysis &indo&
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STARTING OF SIB PHASE MACHINE
In this section siulation results &ere copiled for the starting of the achine &ith
oth the channels and loading it fro there. t '.+ second it is ale to reach the rated
speed and it &as iediately loaded to rated load and after soe tie it settled at the
synchronous speed.
%ie in seconds8igure *.3" speed profile during starting
%ie in seconds
8igure *.33 2rofile of %or=ue de$eloped
In the tor=ue profile the sudden increase of tor=ue at '.+ second is due to the sudden
application of load on the achine and after soe tie it cae do&n and settled.
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%ie in seconds
8igure *.34 #ac? 5/8 profile during the speed uild up
In the ao$e sho&n profileB the coutation notches are clearly $isile. %he ac?
ef is still increasing trend as the speed is still increasing and the dri$e has still not
reached the rated speed.
In this chapter &e ha$e seen siulation results for oth single and dual
channel dri$es for speed and load $ariations along &ith startup also. 8irstly the
siulations for single dri$e are presented and the supply current %, cae out
around 3'.these dri$es has less cople(ity &hen copared &ith doule channel
dri$e. %he cople(ity can e in the controller as &ell as &e ha$e the utual
coupling effects &hen &e ipleent the achine &ith t&o set of stator &indings
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phase shifted &ith 3'o
et&een the .d$antages of these dri$es can e in
ipro$eent of po&er =uality in the supply current as &ell single achine used
for increasing po&er rating applications. s these dri$e otors are &ith single
rotor and the starting of the achine can e handled &ith single channel only. Eith
this dual dri$e the supply current %, drastically reduces to half of the single
channel and if &e design a suitale passi$e filter it can e &ithin the I555
recoendations.
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CHAPTER
MODIFIED LCI DRIVE
%he pre$ious chapters discussed t&o different LCI dri$e configurations naely si(
pulse and t&el$e pulse -dual channel &here the front end con$erter is a phase
controlled thyristor con$erter as sho&n in 8ig ).1. o&e$erB ost of the applications
of these dri$es are of not regenerati$e nature and hence there are se$eral odified
front end configurations possile. %he one &hich &ill e discussed in this chapter is
one of the configurations &hich are reported in literature 1*D.
Source side con$erter /otor side con$erter
8ig ).1 #loc? diagra of LCI fed synchronous dri$e
INTRODUCTION
In this configuration the odification is done at the front end con$erter. %hethyristor con$erter is replaced y the diode ridge rectifier and for ipro$eent in
po&er =uality t&el$e pulse C to ,C con$erter is used &hich is sho&n in 8ig ).". 8or
the controllale actionB an e(tra con$ersion stage has een added in the for of a uc?
chopper and then a controlled ,C $oltage is fed to the otor side con$erter through a
,C lin? inductor for eulating a fairly constant current source.
/otor side con$erter
8ig )." #loc? diagra of LCI fed synchronous dri$e &ith chopper rectifier
configuration 1*D
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IMPLEMENTATION OF THE MODEL IN MATLA8SIMULIN6
%he odeling in the /%L# > SI/ SI/
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$i. DC "ink ReactrF %his inductor acts as a filter to sooth out the ,C lin?
current and to allo& the t&o con$erters to operate independent of each other.
$ii. Mtr 'i#e In(erterF Input to this loc? is ,C $oltage fro the source side
con$erter and firing pulses. 8iring pulses to this loc? is gi$en through an S;
functionB &hich changes the firing se=uence ased on rotor position. Output
of this loc? is 3 phase currentsB &hich flo& through the achine.
$iii. S*ncrn)' Mtr &"ckF %his loc? has een created using the
synchronous achine odel a$ailale in Si2o&erSystes -2o&er Syste
#loc?set in per unit configuration and the achine easureents deu(.
%he achine paraeters are defined in per unit representation. Input to the
arature coes fro load;side Con$erter #ridge. 8ield $oltage and Load
tor=ue are to e gi$en as inputs. Outputs fro this loc? are $arious
=uantities that can e easured fro the achine such as speedB
electroagnetic tor=ueB flu( lin?agesB currents and po&er.
i(. Cntr""erF Controller is the heart of the LCI dri$e as this is the unit &hich
controls the firing of chopper and load side thyristor ridges through the
feedac? signals of the speed current $oltage etc. /odel for the Controller
de$eloped for the LCI dri$e is sho&n in 8igure ).3. %he ain susystes of
the controller are e(plained elo&.
e #iring angle ontrol: %his susyste has een de$eloped using S;
8unction. It senses the rotor speedB ,C lin? current and the rotor
position to decide &hether the syste shall e operated in the fi(ed
firing ode or the selfcoutated ode.
f $% ontrollers: 2I controllers are used to generate the reference ,C
lin? current $alue -&hich is an inde( of the tor=ue re=uireent ygenerating the error signal y coparing the reference and actual speed
of the otor. %his speed error is also needed to control the closing of
the circuit rea?ers of the other channel &hen the dri$e is operated in the
t&el$e pulse ode.
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mod +2=1>8>>0 utput &466>2$
0& 1'23
4$4$ "6 8 &
#C;"uncti on?
wm
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8urther the ,C lin? reference signal output fro the first 2I controller -speed
controller is copared &ith the actual ,C lin? current $alue y the second 2I
controller -current controller to arri$e at the pulse for the chopper. %he t&o 2I
controllers are sho&n in 8igure ).* and 8igure ).).
8ig ).* 2I Speed controller
8ig ).) 2I Current Controller
%he rectifier chopper ased LCI dri$e is odeled for three phase synchronous
achine. s &e ?no& LCI dri$e control can e copared &ith ,C otor. In ,C
otor the speed is controlled y $oltage supplied to it and the sae is &ith the LCI
.in the con$entional LCI the $oltage is controlled y front end %hyristor #ridge
&here as in this odel the $oltage is controlled y ,C;,C uc? chopper. %he front
diode ridge rectifiers can e connected in parallel or series connections. If &e
connect the in parallel the $oltage le$el increases and current le$el decreases in
the ,C lin? area and the con$erter efficiency can e increased &ithout and the
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o$erall dri$e efficiency &ill not e hapered &ith adding one ore con$erter stage
in the dri$e.
In this chapter the coplete odel has een de$eloped along &ith controller
part also. %he controls include t&o parts i.e. one is speed control and other is
fre=uency control. %hese controls re=uire the inputs as speedB rotor angleB dc lin?
current and these are copared &ith reference $alues and generate the s&itching
signals. 8or this odel siulations are carried out for oth types of achines of
different po&er ranges. %he siulations are carried for load and speed $ariations.
%he starting of the achine also done &ith the help of pulsed ode of operation.
In the ne(t chapter the siulation results are presented for oth 6%2C achine
as &ell 3.* : achine the 2G achines la.
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CHAPTER 2
SIMULATION RESULTS AND DISCUSSIONS
In the pre$ious chapter /%L#>SI/
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%ie in seconds
8igure 0.1 Speed profile under the load and speed $ariation
%ie in seconds
8igure 0." Instantaneous tor=ue profile
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%ie in seconds
8igure 0.3 #ac? 5/8 profile of the /achine
%ie in seconds
8igure 0.4 Stator current profile
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%ie in seconds
8igure 0.* Supply current profile
8igure 0.) %, of input current
%he controller used consists of 2I controllers here &e ha$e the prole of steady
state error &hich can e noted fro the speed profile -8igure 0.1. In the tor=ue
profile -figure 0." &ith sudden decrease of speed at rated load the tor=ue has
increased ore than rated for attaining load &hich can &e get a clear picture fro
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profile. In the ac? 5/8 profile -8igure 0.3. Ee are ale to see the $oltage notches
during the s&itching instants of otor side con$erter. Eith supply current profile
-8igure 0.* &e are ale to see it as it is not =uasi s=uare &a$e in nature &ith high
%, around 3' ut is on the side of sinusoidal nature.
SIMULATION OF THE /.1 6VA MACHINE INTHE LA8
%he otor is started &ith an initial load of '.3 p.u and the speed reference is gi$en
as 1 p.u. %hen &e set the load $ariation fro '.3 to rated .! p.u at 1st sec %he speed
$ariation &ith these $ariations is sho&n in 8igure 0.0. %he current liit is set at the
rated $alue as per the specifications of the dri$e anufacturer and the usual
operational practices adopted for starting of the dri$e. %hree phase ac? ef profileis sho&n in 8igure 0.+B &hich is full of notches and spi?es due to current
coutation. %hree phase otor currents are sho&n in 8igure 0.!
%ie in seconds
8igure 0.0 Speed profile under the load and speed $ariation
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%ie in seconds
8igure 0.! Stator current profile
%ie in seconds
8igure 0.+ #ac? 5/8 profile of the /achine
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%ie in seconds
8igure 0.1' Supply current profile under the load
8igure 0.11 %, analysis of Supply current
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STARTING OF THE LA8 MACHINE 4ITH MODIFIED MODEL
%ie in seconds
8igure 0.1" Speed profile during starting
%ie in seconds
8igure 0.13 In$erter pulses during starting
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s &e ?no& the synchronous achine is not starting &e ha$e to a?e soe
special arrangeent for starting. In the pre$ious odel &e ha$e ta?en oth the feed
ac?s i.e. speed as &ell as rotor angle theta. #ut in this controller &e ha$e ta?en only
one feedac? that is speed and &e integrated to get rotor angle.
%hen as pre$iously &e ga$e three inputs angleB speed and dc lin? current and
de$eloped the logic of pulsed ode of operation until the speed is up to 1' of the
rated speed
%he input coand -speed is gi$en as rap coand and gi$en a
coand to raise its speed up to rated speed in 1 second tie span. Ee can see the
speed profile of the achine in the 8ig 0.1". t 1." nd second the achine suddenlyloaded up to rated load and &e can notice soe speed dropped suddenly &hich cae
ac? after soe tie.
%he other profiles of #ac? 5/8 and currents are sae as &e seen for the pre$ious
starting of other achines &hich ha$e sho&n in pre$ious chapter .%he 8ig 0.13 sho&s
the in$erter firing pulses for the si( s&itches. In this &e can see the fre=uency of the
pulses is increasing as the achine speed increasing soothly &hich is the techni=ue
of self controlled synchronous achine
Eith this rectifier chopper ased LCI dri$e odel siulations results are presented
for oth achines of different po&er ranges in this chapter. #y noticing the %,
&indo& &e can conclude that &ith this odel also &e cannot liit the supply current
%, under the recoendations. 8or restricting &ithin the liits &ith this odel &e
ha$e to insert the passi$e filter for doinant haronic eliination. 8or proper design
of filter coponents &e ha$e to adopt soe ad$anced techni=ue so that there &ill note any tuning proles. In the ne(t chapter this odel hard &are ipleentation
docuentation has een pro$ided &ith the detail description of the each and e$ery
odule and interfacing circuits are e(plained.
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CHAPTER 3
HARD4ARE IMPLEMENTATION OF THE MODIFIED LCI DRIVE
Eithout the ipleentation of hard&are no project &ill e a fruitful jo. %his
project also consists of hard&are ipleentation of the project. %he odified
-chopper LCI fed synchronous achine hard&are ipleented along &ith the help
of TMS/-F-3,- DSP controller
8ig !.1 Outline diagra of the hard&are set up
INTRODUCTION
%he eYdsp%/ 8"!1" is a stand;alone card;;allo&ing e$aluators to e(aine the
%/S3"'8"!1" digital signal processor -,S2 to deterine if it eets their
application re=uireents. 8urtheroreB the odule is an e(cellent platfor to de$elop
and run soft&are for the %/S3"'8"!1" processor. %he eYdsp%/ 8"!1" is shipped
&ith a %/S3"'8"!1" ,S2. %he eYdsp%/ 8"!1" allo&s full speed $erification of
8"!1" code. %&o e(pansion connectors are pro$ided for any necessary e$aluation
circuitry not pro$ided on the as shipped configuration.
%o siplify code de$elopent and shorten deugging tieB a C"''' %ools Code
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Coposer dri$er is pro$ided. In additionB an onoard @%G connector pro$ides
interface to eulatorsB operating &ith other deuggers to pro$ide assely language
and WCH high le$el language deug.
%he eYdsp%/
8"!1" has the follo&ing featuresF
Z %/S3"'8"!1" ,igital Signal 2rocessor
Z 1*' /I2S operating speed
Z 1! &ords on;chip 9/
Z 1"! &ords on;chip 8lash eory
Z )4 &ords off;chip S9/ eory
Z 3' /z cloc?
Z " 5(pansion Connectors -analogB I>O
Z Onoard I555 114+.1 @%G Controller
Z *;$olt only operation &ith supplied C adapter
Z %I 8"!(( Code Coposer Studio tools dri$er
Z On oard I555 114+.1 @%G eulation connector
De'cri7tin f Har#!are 'et)7
coplete o$erall loc? diagra of the set up is sho&n in 8ig !.1.%he entire setupcan e di$ided into three groups naely controllerB interfacing de$ices and po&er
circuit coponents. Ee ha$e already discussed aout the controller in pre$ious su
section and the rest part &ill e discussed here.
8irstly &e discuss aout the interfacing circuits &hich can e sudi$ided as sensor
circuit and opto coupler and isolation circuit .the po&er circuit consists of t&el$e
pulse diode ridge rectifierB uc? chopperB %hyristor #ridgeB dc lin? inductor and
three phase synchronous achine. Ee &ill e discussed each one separately in the
follo&ing discussion.
SENSOR CIRCUIT
s &e ?no& for closed loop operation &e ha$e to sense the =uantities and copare
&ith the reference $alues to nullify the error ut the =uantities should e fed into the
controller through the ,C channels &hich are copatile &ith $ery lo& $alues
that is &hy &e re=uire an interface et&een the po&er =uantities and controller %his
circuits eets the re=uireents ao$e discussed points i.e. the ,C input to ,S2
&ill e in the range of ' to 3 $olts.
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8ig !." Sensor circuit diagra
OPTO@COUPLER AND ISOLATION CIRCUIT
s entioned efore the signals generated y the "!1" processor are at a $oltage
le$el of 3.3: &hereas the in$erter needs the pulses at a $oltage le$el of 1*:. 8or this
$oltage oost up and to electrically isolate the 1* : ground &ith the ,S2Hs 3.3:
groundB &e a?e use of the opto coupler circuit sho&n in 8ig !.".
8ig !.3 Opto coupler and isolation circuit
%he input transistorHs ase resistance &as designed so that ore than " &ould not
e dra&n fro the "!1" output pin. %here is no in$ersion in this circuit and an input
high pulse of 3.3: &ill pro$ide an output high pulse of 1*:.
T4ELVE PULSE DIODE 8RIDGE RECTIFIER
s &e sho&n in the odel it is t&o si( pulse ridges connected in parallel to otain a
sooth dc $oltage than copared to si( pulse one. %hese diode ridge rectifiers gi$e
plenty of options &ith $ariety of configurations for achie$ing t&el$e pulse
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configurations &hich can e ipleented &ith aintaining 3''et&een t&o si( pulse
ridges so that effecti$ely &e get t&el$e pulse C to ,C con$erter
DC@DC 8UC6 CHOPPER
%he ne(t stage of con$ersion after C to ,C con$ersion is to get a controlled ,C
$oltage at the input of the LCI in$erter so that &e can control the speed of the dri$e.
%o control $oltage &e ha$e inserted the chopper stage. %his can e a$ailale in the
odule of Sei?ron a?e the $oltage le$el &e &ant along &ith input capacitor for
aintaining the input $oltage constant to the chopper s&itch.
DC LIN6 INDUCTOR
fter the stage of getting controlled $oltage it is get a constant current to feed the
in$erter &hich is realized y connecting a high $alue of inductor in the ,C lin? so
that a constant current flo&s through the in$erter legs. %his high $alue inductor also
gi$es ad$antage that oth con$erters operate independtly &ithout affecting each other.
%he $alue of inductor &ill e in the range of illi henrys. %he operating fre=uency of
the inductor depends upon the s&itching fre=uency of the uc? chopper. s &e ha$e
thyristors &e cannot s&itch in $ery high ranges so it can e a(iu up to one ?ilo
hertz
THYRISTOR 8RIDGE INVERTER
t the last stage of con$ersion the controlled ,C is con$erted into the C to feed the
three phase synchronous achine. %hese in$erters are a$ailale in odules of
sei?ron a?e. In this set up &e used the a$ailale odule -"* : for our
application. In this &e donHt ha$e any gate dri$e circuit as they pro$ide &ith the IG#%
in$erter odules therefore &e re=uire proper dri$e and isolation circuit to fire the
thyristors properly &ithout shorting there cathode terinals each other.
In this chapter each and e$ery iportant odule as &ell as interfacing circuits
for proper functioning of the dri$e. %he &hole setup has een ipleented e(cept
the thyristor firing isolating circuit so that cathodes &ill not e shorted of t&o
de$ice.
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CHAPTER@5
CONCLUSION AND SCOPE FOR FUTURE 4OR6
%he project ai is to ipro$e the po&er =uality ipro$eent of the LCI fed
synchronous achine. In this direction first the odel &as de$eloped for the single
channel that is for three phase synchronous achine. Single channel odel &as
de$eloped &ith data pertaining to 6%2C station achine. %he siulations for speed
and load $ariations ha$e done and analyzed the &a$e fors. s synchronous achine
is not a self starting it has started fro zero speed &ith the help of controllers &hich
ta?e care of proper pulses for getting the starting tor=ue.
In the first step of ipro$ing the po&er =uality &e ha$e ta?en the doule channel
LCI fed synchronous dri$e. It is ipleented in t&o &ays i.e.B &ith t&o three phase
achines rotor coupled and &ith si( phase achine -in &hich stators are 3''phase
shifted.8or oth these achines load and speed $ariations are carried out and
&a$efors analyzed. %he sae as single channel starting echanis has een
ipleented for the doule channel achines in oth configurations
s further ipro$eent of the LCI dri$e front end con$erter replaceent has done
for ipro$eent in dri$e perforance and it has een ipleented in hard&are.
FUTURE SCOPE OF 4OR6
Eith odule used as LCI con$erter gate dri$e circuit is not present and the proper
gate dri$e along &ith isolation circuit to e designed and prepared for firing thyristor
of the in$erter
In this controller the rotor angle used in S functions is otained y integrating the
speed coand. #y proper estiation or sensing the rotor angle dri$e can e
successfully ipleented &ith this controller
Eith this configuration the po&er =uality is increased ut it is not &ithin
recoended liits and it can e ought y inserting a passi$e filter designed for
doinant haronics in the supply side current. Eithout passi$e filter y going for
higher pulse &e can achie$e the po&er =uality nors under the liits
.
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REFERENCES
1. G. . ,uey J2o&er Seiconductor controlled dri$esKB 2rentice all
InternationalB
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11. Si2o&erSystesB /%L# and SI/
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C 418> >6+$'2F
C;7 3 >6+$'2F
?#%5 3
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8ield &inding res. at 0*PC r"[ Oh '.30
Yero se=uence res. r' p.u. ".0*
rature &inding lea?age reactance (s1 p.u. '.'0
Yero se=uence reactance (' p.u. '.'46egati$e se=uence reactance (" p.u. '.'!)
,irect a(is arature reactance (hd p.u. '.!1
]uadrature a(is arature reactance (h= p.u. '.0"
,irect a(is synchronous reactance (d p.u. 1.'
,irect a(is transient reactance (d[ p.u. '.11
,irect a(is sutransient reactance (d[[ p.u. '.'!*
]uad. a(is synchronous reactance (= p.u. '.!']uad. a(is sutransient reactance (=[[ p.u. '.'+*
,irect a(is transient sc tie constant %d[ s '.""
,irect a(is sutrans. sc tie constant %d[[ s '.'1)
]uad. a(is sutrans. sc tie constant %=[[ s '.'"
,irect a(is transient oc tie constant %do[ s 1.+
,irect a(is sutrans. oc tie constant %do[[ s '.'"4
]uad. a(is sutrans. oc tie constant %=o[[ s '.'"rature sc tie constant % s '.'"0
,C LI6 I6,
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S 6O ,5SC9I2%IO6
1 9ating +'' :
" : &inding ))'' :
3 L: &inding 1"*' :4 2ositi$e se=uence ipedance at 0* deg c principal tap 11
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C pulse operationF
?C;% 3
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). 6egati$e se=uence res. ri p.u. 13.* 13.*
0. rature &inding lea?age
reactance(s1
p.u.'.'00 '.')*
(s1e p.u. '.'3" '.'"0(s1? p.u. '.'4* '.'4'
!. 8ield &inding lea?age reactance (s"[ p.u. '.')" '.'*"
+. ,aper &inding lea?age reactance (s3[ p.u. '.'43 '.'3+
1'. Yero se=uence reactance (' p.u. '.'44 '.'3*
11. 6egati$e se=uence reactance (" p.u. '.1' '.'!
1". ,irect a(is arature reactance (hd p.u. '.!" '.0*
13. ]uadrature a(is araturereactance
(h= p.u. '.04 '.)4
14. ,irect a(is synchronous reactance (d p.u. '.!! '.!'
1*. ,irect a(is transient reactance (d[ p.u. '.14 '.11
1). ,irect a(is sutransient reactance (d[[ p.u. '.'!" '.'01
10. ]uadrature a(is synchronous
reactance(= p.u.
'.!' '.0"
1!. ]uadrature a(is sutransientreactance
(=[[ p.u. '.'+* '.'0*
1+. ,irect a(is transient sc tie
constant %d[ s '.34 '."!
"'. ,irect a(is sutransient sc tie
constant%d[[
s'.'10 '.'11
"1. ]uadrature a(is sutransient sc
tie constant%=[[ s '.'"3 '.'10
"". ,irect a(is transient oc tie
constant
%do[s
".4" ".')!
"*. ,irect a(is sutransient oc tie
constant%do[[
s'.'"" '.'1)
"3. ]uadrature a(is sutransient oc
tie constant%=o[[ s '.10* '.1*"
"4. rature sc tie constant %G s '.'3) '.'"+
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,C LI6 I6,
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APPENDIB 8
S#&'C(%)' * +%', S%-, C)'V,.(,. #%.%'/
function sysB ('D lscf-tB(BuBflag
if flag 3B
(' u-1N rotor angular position
& u-"N rotor speed
dclin? u-3N
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
8or otor speed elo& 1'B line side con$erter firing is stopped e$ery si(ty
degrees to a?e dc lin? current zero for load side current coutation.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
if -&_'.1`-('1``-dclin?_'.1B sys1 1 1 1 1 1DNendN
if -&_'.1`-('"B sys' ' ' ' ' 'DNendN
if -&_'.1`-('3``-dclin?_'.1B sys1 1 1 1 1 1DNendN
if -&_'.1`-('4B sys' ' ' ' ' 'DNendN
if -&_'.1`-('*``-dclin?_'.1B sys1 1 1 1 1 1DNendN
if -&_'.1`-(')B sys' ' ' ' ' 'DNendN
if -&_'.1`-('0``-dclin?_'.1B sys1 1 1 1 1 1DNendN
if -&_'.1`-('!B sys' ' ' ' ' 'DNendN
if -&_'.1`-('+``-dclin?_'.1B sys1 1 1 1 1 1DNendN
if -&_'.1`-('1'B sys' ' ' ' ' 'DNendN
if -&_'.1`-('11``-dclin?_'.1B sys1 1 1 1 1 1DNendN
if -&_'.1`-('1"B sys' ' ' ' ' 'DNendN
if -dclin?'B sys1 1 1 1 1 1DNendN
if -&'.1B sys1 1 1 1 1 1DNendN
elseif flag 'B
(' DN
sys ' ' ) 3 ' 1DN
else
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Output is set to D.
sys DN
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end
S #&'C(%)' * #%0,- #%.%'/
function sysB ('Dfi(ed-tB(BuBflagB?
if flag3B
inputsF positionB speed controller output>? -reference current aplitudeN
posu-1N
iru-"N
sector selection fro ' degrees -';)'N)';1"'...N
if -sin-posXpi>4_-s=rt-3>"``-cos-posXpi>4'.*``-sin-posXpi>4'B
iar'Nir'Nicr'Nean1Nen1Necn'NendN
if -sin-posXpi>4-s=rt-3>"``-a1s-cos-posXpi>4_'.*B
iar'Nir'Nicr'Nean'Nen1Necn1NendN
if -sin-posXpi>4_-s=rt-3>"``-cos-posXpi>4_;'.*` -sin-posXpi>4O'B
iar1Nir'Nicr'Nean'Nen'Necn1NendN
if -sin-posXpi>4;-s=rt-3>"``-cos-posXpi>4_;'.*``-sin-posXpi>4_'B
iar1Nir1Nicr'Nean'Nen'Necn'NendN
if -sin-posXpi>4_;-s=rt-3>"``-as-cos-posXpi>4_'.*B
iar'Nir1Nicr1Nean'Nen'Necn'NendN
if -sin-posXpi>4;-s=rt-3>"``-cos-posXpi>4'.*``-sin-posXpi>4_'B
iar'Nir'Nicr1Nean1Nen'Necn'NendN
sysiar ir icr ean en ecnDN
elseif flag'B
('DN
sys' ' ) 1 ' 1DN
else sysDN
end
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S #&'C(%)' * +)A- #%.%'/
function sysB ('D loadfiring-tB(BuBflag
if flag 3B
(' u-1N rotor position
if -('3B sys1 ' ' ' ' 1DNendN
if -('4B sys1 1 ' ' ' 'DNendN
if -('*B sys' 1 1 ' ' 'DNendN
if -(')B sys' ' 1 1 ' 'DNendN
if -('1B sys' ' ' 1 1 'DNendN
if -('"B sys' ' ' ' 1 1DNendN
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
#ased on rotor positionB thyristor coination firing is decided
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
elseif flag 'B
%his part ta?es care of all initializationN it is used only once.
(' DN
%he syste has no statesB si( outputsB and one input.
