60707871 pe s lab manual student copy

8/13/2019 60707871 PE S Lab Manual Student Copy

1/67

Power Electronics & Simulation Lab

INDEX

Add-on Experiments

EEE Department, SVEC, Tadepalligudem Page 1

Sl.No. EXPERIMENT NAME Page No.

1 Characteristics of SCR, BJT and MS!ET "

" #$TE firin% circuits of SCR 11

1'( $C )olta%e controller with R & RL loads 1*

+ 1' ( !ull controlled brid%e Con)erter with R & RL loads 1-

* .C J/ES cho00er ""

1' ( Parallel in)erter with R & RL loads "*

2 1' ( 3alf'controlled Con)erter with R & RL loads "-

- 1' ( Series in)erter with R & RL loads "

4PSP5CE Simulation of 1' ( !ull con)erter usin% RLE loads and

1'( $C )olta%e controller usin% RLE loads*

16 PSP5CE Simulation of Resonant 0ulse commutation circuit and Buc7cho00er

+1

Sl.No. EXPERIMENT NAME Page No.

11 1'( .ual con)erter with R & RL loads8 +-

1" PSP5CE Simulation of sin%le 0hase 5n)erter with P9M control *"

1 !orced commutation circuits of SCR *

1+ 1' ( Cclo con)erter with R & RL loads


2/67


1. CHARACTERISTICS OF SCR , BJT and MOSFET

(a) STATIC CHARACTERISTICS OF SCR

AIM :

To 0lot the characteristics of SCR and to find the forward resistance holdin% currentand latchin% current8

APPARATUS

1; C3$R$CTER5ST5CS ST


3/67


4) $d?ust 5%1to some )alue sa 16m$ b )arin% >" or %ate current 0otentiometerR")ar >1 and note down >$@and 5$RE$.5/#S8

5) !urther )ar >1till SCR conducts, this can be noted b sudden dro0 of >$@and 5$readin%s8

6) .raw the %ra0h >$@)s 5$82; Re0eat the same 0rocedure for different %ate currents8

MODE" !RAPH

TO FIND "ATCHIN! CURRENT AND HO"DIN! CURRENT

1) $00l about "6> between anode and cathode b )arin% >182) @ee0 the load 0otentiometer R1in minimum 0osition8

; The de)ice must be in the !! state with %ate o0en84) #raduall increase %ate )olta%e >"till the de)ice turns /8 This is the minimum %atecurrent reAuired to turn / the de)ice8

*; $d?ust the %ate )olta%e to a sli%htl hi%her )alue and set the load 0otentiometer at themaimum resistance 0osition, the de)ice should come to !! state8

; The %ate )olta%e should be 7e0t constant in this e0eriment87) B )arin% R1, %raduall increase anode current 5$ in ste0s88) 0en and close the %ate )olta%e >"switch after each switch84; 5f the anode current is %reater than the latchin% current of de)ice, the de)ice stas /

e)en after the %ate switch is o0ened otherwise the de)ice %oes in to bloc7in% mode as

soon as the %ate switch is o0ened816; /ote down the latchin% current8



4/67


11)5ncrease the anode current from the latchin% current le)el b load 0ot R1or >1812)0en the %ate switch 0ermanentl, the thristors must be carefull /813)/ow start reducin% the anode current %raduall b ad?ustin% R1814)5f the thristor does not turns !! e)en after the R1at maimum 0osition then reduce

>181*; bser)e when the de)ice %oes to bloc7in% mode81; The anode current at this instant is holdin% current of the de)ices817)Re0eat the ste0s a%ain to %et the holdin% current 538

TABU"AR FORM

S.NO. #BO1$ , I!1$ #BO%$ , I!%$

#A&(#)

IA(A) #A&(#)

IA(A)

RESU"T



5/67


(') CHARACTERISTICS OF I!BT

AIM To 0lot the in0ut and transfer characteristics of an 5#BT to find / state resistance

and the transfer conductance8APPARATUS

1) 5#BT 1R# BC "6S2) Resistors 16@D"*w, 2*D"*93) .C )oltmeter 6'*6>4) .C )oltmeter 6'1*>5) .C ammeter 6'*66m$

THEOR 5t is a new de)elo0ment in the area of 0ower MS!ET technolo%8 This

de)ice combines in to ad)anta%es of both MS!ET and BJT8 So an 5#BT has hi%h in0utim0edance li7e as MS!ET and low / state 0ower li7e BJT8 !urther 5#BT is free fromsecond brea7down 0roblem 0resent in BJT8 5#BT is also 7nown as metal oide insulated %atetransistor8

5t was also called as insulated %ate transistor8 The static characteristics or out0utcharacteristics of 5#BT shows 0lot of collector current 5C)s collector emitter )olta%e >CEfor )arious )alues of %ate emitter )olta%e8 5n the forward direction the sha0e of out0utcharacteristics is similar to that of BJT and ha)e the controllin% 0arameter is %ate'emitter)olta%e >#E because 5#BT is a )olta%e controlled de)ice8 The de)ice de)elo0ed bcombinin% the areas of field effect conce0t and technolo%8

CIRCUIT DAI!ARAM



6/67


PROCEDURE TRANSFER CHARACTERISTICS

1; Ma7e connections as 0er the circuit dia%ram82) 5nitiall 7ee0 >1and >"minimum and set >1F >CE1; G 16>8

3) Slowl )ar >"i8e8, >#Eand note down 5Cand >#Ereadin% for e)er 1>84) Re0eat the same 0rocedure for different )alues of >CEand draw the %ra0h >#E)s8 5C8

CO""ECTOR CHARACTERISTICS

1) 5nitiall set >"i8e8, >#Eto *>8 Slowl )ar >1and note down 5Cand >CE82) !or a 0articular )alue of >#E1there is a 0inch off )olta%e >Pbetween collector andemitter83) Re0eat the same for different )alues of >#E and draw the %ra0h between >CE )s 5C

MODE" !RAPH



7/67


TABU"AR FORM

S.NO #CE1$ #CE%$

#!E(#)

IC(A)

#!E(#) IC(A)

S.NO #!E1$ #!E%$

#CE(#)

IC(A)

#CE(#) IC(A)

RESU"T

(*) CHARACTERISTICS OF MOSFET



8/67


AIMTo 0lot the in0ut and transfer characteristics of a MS!ET to find / state

resistance and the transfer conductance8APPARATUS

1) MS!ET 5R! 2+62) Resistors 16@D"*w, 2*D"*9, +@D"*93) .C )oltmeter 6'*6>4) .C )oltmeter 6'1*>5) .C ammeter 6'*66m$

THEOR$ metal oide semiconductor field effect transistor is a recent de)ice de)elo0ed b

combinin% the areas of field effect conce0t and technolo%8The transfer characteristics of MS!ET shows the )ariation of drain current 5 .as a

fuction of %ate source )olta%e >#S8 The de)ice is in !! state u0to some )olta%e calledthreshold de)ice )olta%e8 The out0ut characteristics of Power MS!ET indicate the )ariation

of .rain current 5.as a function of .rain source )olta%e >.Sas a 0arameter8This de)ice combines into ad)anta%es of 5#BT and BJT8 So this de)ice has hi%him0edence and low / state 0ower li7e BJT8 5t is a new de)elo0ment in the ared of 0owerMS!ET technolo%8 $ll the de)ices are mounted on 0ro0er heat sin78 Each de)ice is

0rotected b snubber circuit8

PROCEDURETRANSFER CHARACTERISTICS

1; Ma7e connections as 0er the circuit dia%ram82) 5nitiall 7ee0 >1and >"minimum and set >1F >.S1;G 16>83) Slowl )ar >"i8e8, >#Sand note down 5.and >#Sreadin% for e)er 1>84) Re0eat the same 0rocedure for different )alues of >.S and draw the %ra0h >#S)s

5.8

CO""ECTOR CHARACTERISTICS

1) 5nitiall set >"i8e8, >#Sto 8*>82) Slowl )ar >1and note down 5.and >.S83) !or a 0articular )alue of >#S1there is a 0inch off )olta%e >Pbetween drain and

source84) Re0eat the same for different )alues of >#S and draw the %ra0h between >.S )s 5.



9/67


CIRCUIT DAI!RAM

MODE" !RAPH

TABU"ARFORM



10/67


TRANSFER CHARACTERISTICS

S.NO #DS1$ #DS%$

#!S(#) ID(A)

#!S(#) ID(A)

DRAIN CHARACTERISTICS

S.NO #!S1$ #!S%$

#DS(#) ID(A)

#DS(#) ID(A)

RESU"T

%. !ATE FIRIN! CIRCUITS OF SCR



11/67


AIM

To stud and com0are resistance firin% circuit with the resistance'ca0acitance firin%circuits8

APPARATUS

1; Control 39R and !9R usin% resistance circuits8"; Rheostat *6D"$3) CR+; connectin% wires

THEOR

The most common method for controllin% the onset of conduction in an SCR is bmeans of %ate )olta%e control8 The %ate control circuit is also called as firin% or tri%%erin%

circuits8 These %atin% circuits are usuall low 0ower electronic circuits8 The firin% circuitshould fulfill the functions8 $n SCR can be switched from !! state to / state in se)eralwas8 These are forward )olta%e tri%%erin%, d)Ddt tri%%erin%, li%ht tri%%erin% is used in somea00lications 0articularl in a series connected strin% %ate tri%%erin% is the most commonmethod of turnin% / the SCR at desired instant of time8

PROCEDURE

R+TRI!!ERIN!

1; Ma7e connections as 0er the circuit dia%ram8

"; Connect the rheostat of *6D"$ between the load 0oints8; >ar the control 0ot and obser)e the )olta%e wa)eform across the load, SCR and

different 0oints of circuits8+; 9e can )ar the firin% an%le from 6 to 46 de%rees onl in R'tri%%erin%8 5n this

snchroniHed firin% an%le can be obtained easil and economicall in the half'ccle of the su00l8

5) But there is a drawbac7 that firin% an%le can controlled at the most at 466since the%ate current is in 0hase with the a00lied )olta%e8

6) $ resistance is connected in series with the control 0ot so that the %ate currentdoes not cross the maimum 0ossible )alue 5#ma8

2; .raw the wa)eform across the load and de)ice for different )alues of firin%an%les8

RC+TRI!!ERIN!

1; Connect a ca0acitor to R'tri%%erin% circuit to realiHe RC tri%%erin%8



12/67


2) Re0eat the abo)e 0rocedure and draw the wa)eforms across the load and de)icefor different )alues of firin% an%les88

CIRCUIT DIA!RAM S

MODE" !RAPH



13/67


CA"CU"ATIONS

$)era%e out0ut )olta%e:

> G Vm2!"!Vm#in$t d$t

G Vm2!F1ICS;

>RMSG 12!"!Vm2#in2$t d$t K

TABU"AR FORM

R+FIRIN!

S.NO F-ngangle

PRACTICA" THEORITICA"

#M( #) #A#!(#) #RMS(#) #M( #) #A#!(#) #RMS(#)

RC+FIRIN!

S.NO F-ngangle

PRACTICA" THEORITICA"

#M( #) #A#!(#) #RMS(#) #M( #) #A#!(#) #RMS(#)

RESU"T



14/67


/. SIN!"E PHASE A.C. #O"TA!E CONTRO""ER

AIM:To obser)e the out0ut wa)e forms of 1'0hase $8C8 )olta%e controller with R and RL

loads usin% SCRs8APPARATUS

1; SCRFtn1";'"

"; Rheostat *6D"$; 5nductor *6Mh+; Cathode ra oscillosco0e*; Connectin% wires

THEORB connectin% the re)erse 0arallel 0air of SCRs or TR5$C between $C su00l and

load the )olta%e a00lied to load can be controlled8 This t0e of 0ower controller or re%ulator8Some of the main a00lications of $C )olta%e re%ulator are for domestic and industrialheatin%8

Transformer ta0 chan%in%, li%htenin%, s0eed control of 1'0hase and '0hase $Cdri)es and startin% of induction motors earlier8 The de)ices used for a00lications are $uto

transformers, ta0 tDf, ma%netic am0s, saturable and triac based controller because of their hi%hefficienc fleibilit in control8 Com0act siHe and less maintaince8 $8C8)olta%e controllersare also closed loo0 control sstems8

PROCEDURE1; Switch on the main su00l of the firin% circuit and obser)e tri%%er out0uts b

)arin% the firin% an%le8"; Ma7e sure that firin% 0ulses are 0ro0er before connectin% to the 0ower circuit8; Ma7e the connections as connect the tri%%er 0ulses from firin% circuit to

corres0ondin% SCR TR5$C in 0ower circuit+; Connect the $8C8 su00l to 0ower throu%h ste0 down transformer8

*; Connect the load of *6D"a rheostat8



15/67


; Switch on the ste0 down tDf su00l and tri%%er out0uts and obser)e thewa)eforms in the CR8

2; /ote down the oD0 )olta%e, firin% an%le, 5D0 )olta%e8

Ta'0la- Fo-

S.no F-ng angle P-a*2*al 23eo-e2*al

() #a4g(4)R+load

#-(#)R+load

#a4g(4)R"+ load

#-(4)R"+ load

CIRCUIT DIA!RAM

MODE" !RAPHS



16/67


Re0l2

#I#A 5UESTIONS 1; 9hat is the s0ecialt of an $C )olta%e controller"; 9hat is the de)ice which can re0lace the $C )olta%e controller

; 9hat t0e of commutation is em0loed in this circuit



17/67


6. 1+7 FU"" CONTRO""ED BRID!E CON#ERTER 8ITH R ANDR" "OADS

AIM To stud sin%le 0hase full controlled brid%e con)erter with R and RL loads8

APPARATUS 1; 1'0h con)erter firin% circuit"; 1'0h full controlled 0ower circuit; Rheostat' *6D"$+; 5nductor'*6m3

*; Power sco0e; CR

THEOR$ 1'0h full brid%e con)erter usin% four SCRs is shown in fi%ure8 The load is assumed

to be R and RL8 Thristor 0air T1and T"is simultaneousl tri%%ered and N radians after 0airTand T+is %ated to%ether8

.urin% the 0ositi)e half ccle SCRs T1and T15are forward biased and when theretwo thristors are fired simultaneousl at wt G , the load is connected to the in0ut throu%h T1and T158 5n this case of inducti)e loads durin% the 0eriod N Owt O NI the in0ut )olta%e isne%ati)e and freewheelin% diode .m is forward biased8 .m conducts to 0ro)ide the

conducti)it of current in the inducti)e load8 The load current is transferred from T1and T15

to .Mand thristors T1and T15are turned off due to line or natural commutation8.urin% the ne%ati)e half ccle of the in0ut )olta%e thristors T"and T5"are forward

biased8 The firin% of thristors T"and T"5 simultaneousl at wt G NI will re)erse bias .M8 thediode .Mis turned off and the load is connected to the su00l throu%h T"and T"58

PROCEDURE1; Ma7e the connections as shown in fi%ure2) $00l tri%%erin% 0ulse to SCR T1, T15, T", T"5

; /ow )ar the firin% an%le and note down the readin%s of the out0ut )olta%e8+; bser)e the full controlled wa)eform in CR*; Perform the same o0erations with RL loads and with freewheelin% diode with RL load; $)oid usin% two CR 0robes as there is a 0roblem of short circuit8



18/67


PRECAUTIONS 1; $)oid loose connections"; 9hile turnin% on first turn on the con)erter and then turn on the firin% circuit8; 9hile turnin% off first remo)e the firin% the 0ulses and then turn off the con)erter8

CIRCUIT DIA!RAM S

17 90ll *on4e-2e- :23 R" "oad ; 9-ee :3eelng Dode.



19/67


MODE" !RAPHS



20/67


TABU"AR FORM R+"OAD

Sl No.F-ngAngle ()

O02


21/67


5) The out0ut )olta%e wa)eform for R'load and RL'load with freewheelin% diode aresimilar8 9h

=. DC JONES CHOPPERAIM

To ri% u0 .C Jones cho00er and to control out0ut a)era%e .C )olta%e both atconstant freAuenc and )ariable freAuenc and at different firin% ccles8

APPARATUS

1; .C cho00er 0ower circuit"; .C cho00er firin% circuit; .C re%ulated 0ower su00l 6'6>D"$+; Rheostat *6D"$*; Cathode ra oscillosco0e

THEOR

5n man industrial a00lications, it is reAuired to connect a fied )olta%e .C sourceinto a )ariable )olta%e .C source8 $ .C cho00er con)erts directl from fied .C to )ariable.C and is also 7nown as .C to .C con)erter8 $ cho00er can be considered as .C eAui)alentto an $C transformer with a continuousl )ariable turns ratio8 Li7e a transformer, it could beused to ste0 down or ste0 u0 a .C )olta%e source8 Cho00ers are widel used for tractionmotor control in electric automobiles, trolle cars, marine hoists, for7lift truc7s and minehaulers8 The 0ro)ide smooth acceleration control, hi%h efficienc and fast dnamicres0onse8 Cho00er can be used in re%enerati)e bra7in% of .C motors to return ener% bac7 tothe su00l and this feature results in ener% sa)in%s for trans0ortation sstems with freAuentsto0s8 Cho00er can also be in .C )olta%e re%ulators8

The Jones cho00er is another eam0le of class'. commutation in which a char%edca0acitor is switched b an auiliar SCR to commutate the main SCR8

PROCEDURE

1; Switch on the .C cho00er firin% circuit8"; bser)e the 0oint si%nals and tri%%er out0ut si%nals b carrin% dut ccle and

freAuenc 0otentiometer8; Ma7e sure that tri%%er out0uts are 0ro0er before connectin% to the 0ower circuit8+; /ow, ma7e the interconnections as 0er the circuit dia%ram8*; Connect the .C su00l from the )ariable .C source86) 5nitiall set in0ut .C su00l to 16>87) Connect res0ecti)e tri%%er out0uts from the firin% circuit to the res0ecti)e SCRs in

the 0ower circuit8-; 5nitiall 7ee0 firin% circuit in !! 0osition8

4; Switch on the .C su00l and now su00l main SCR tri%%er 0ulses816; bser)e the )olta%e wa)eform across load8



22/67


11; 5f commutation fails we can see onl the .C )olta%e, in that case switch off the .Csu00l, switch off the 0ulses and chec7 the connections and tr a%ain8

1"; bser)e the )olta%e across the load, across ca0acitor, across main SCR and auiliarSCR b )arin% dut'ccle and freAuenc8

13)/ow )ar the .C su00l u0to 6>8

1+; .raw the wa)eforms at different dut ccle and at different freAuencies81*; Connect )oltmeter and ammeter and note down the )alues8

CIRCUIT DIA!RAM

MODE"!RAPHS

CA"CU"ATIONS



23/67


.G >5/ )olts

TABU"AR FORM

s8no Ca0acitor)olta%e>CF>;

>5/F>;5n0ut)olta%e

T/Fms;/time

T!!Fms;!!time

.utccle F ;

ut0ut )olta%e F>; !reAuencF@3H;

Practical>F>;

Theoretical>F>;

RESU"T

#I#A 5UESTIONS

1; 9hat is cho00er"; 9hat t0e of commutation is em0loed in Jones cho00er; 5s the commutation >olta%e or current+; Mention an a00lications of cho00ers8



24/67


>. 1+7 PARA""E" IN#ERTER

AIMTo stud the 0erformance of center ta00ed transformer t0e 0arallel in)erter at

different freAuencies8

APPARATUS1; Parallel in)erter"; .C re%ulated 0ower su00l; Rheostat *6D"$+; Cathode ra oscillosco0e*; Connectin% wires

THEORThis circuit is a t0ical class'C 0arallel in)erter8 $ssume T/to be in / and TPto be

in !! state8 The lower end of commutatin% ca0acitor is char%ed to twice the su00l )olta%eand remains at the )alue until TPis turned /8 9hen TP is turned /, the current flowsthrou%h the lower end of 0rimar TPand commutatin% inductance L 8 Since the )olta%e acrossc cant be instantaneous the common SCR cathode raises a00roimatel to "> .C andre)erse bias T/8 Thus T/turns !! and C dischar%e throu%h L and su00l and then rechar%esin re)erse direction8 The auto transformation ma7es C to char%e ma7in% now its u00er 0ointto reach I"> .C read to commutate TPwhen T/is /8 The ma?or 0ur0ose of commutationinductance L is to limit the commutation ca0acitance char%in% current durin% switchin%8!reewheelin% diodes .Pand ./assist the in)erter in handlin% the wide ran%e of loads and)alue of C ma be reduced since the ca0acitor now does not ha)e to carr the reacti)ecurrent8 To dam0en the feedbac7 diode currents with in the half 0eriod feedbac7 diodes areconnected to ta0in%s of transformer of "*> ta00in%8

PROCEDURE

1) Switch on the firin% circuit and obser)e the tri%%er out0ut TPand T/b )arin%0otentiometer and b o0eratin% /D!! switch8

"; Connect .C 0ower su00l to 0ower circuit83) Connect tri%%er out0ut to %ate cathode b SCR TPand T/8+; Ma7e the connections as in circuit dia%ram includin% !reewheelin% diodes85) Set in0ut )olta%e to 1*> and a0ll tri%%er 0ulses to SCR and obser)e )olta%e

wa)eform across load86) Remo)e freewheelin% diode and obser)e the wa)eform8 >ar the load and foand

obser)e the wa)eform82; To switch off the in)erter switch off .C in0ut su00l first and then switch off

tri%%er 0ulses8



25/67


CIRCUIT DIA!RAM

MODE" !RAPH S



26/67


PRECAUTIONS

1; Since the 0arallel in)erter wor7s on forced commutation there is a chance ofcommutation failure8 5f the commutation fails there is dead short circuit in the

in0ut .C su00l which will lead to blowin% of in0ut fuse8 Please chec7 the fuse ifthe commutation fails8 Preferabl connect the in0ut .C su00l from 6>D"$Re%ulated 0ower su00l which has o)er current tri00in% facilit thereb

0rotectin% the .C 0ower su00l unit8"; 5f the commutation fails switch !! the .C su00l first and then tri%%er out0ut8

Chec7 the connections a%ain and restart8

TABU"AR FORM

S8/ >.CF>; T/ Fms; !reAurnc F3H; >L$.F>;

CA"CU"ATIONS

Resonant freAuenc fRG 12!C

RESU"T

#I#A 5UESTIONS

1; To what )olta%e will the ca0acitor %ets char%ed"; 9hat is the need of the transformer is the circuit; 9hat t0e of commutation is em0loed in this circuit



27/67


?. 1+7 HA"F CONTRO""ED CON#ERTER 8ITH R AND R" "OADS

AIMTo stud sin%le 0hase half controlled brid%e con)erter with R and RL loads8

APPARATUS

1; 1'0h con)erter firin% circuit"; 1'0h half controlled 0ower circuit; Rheostat' *6D"$+; 5nductor'*6m3*; Power sco0e or CR

THEOR

The circuit arran%ement of a 1'0h con)erter is shown in fi%ure8 5n the 0ositi)e half

ccle thristor T1is forward biased8 9hen SCR T1is fired at t G , the load is connected tothe in0ut su00l throu%h T1and ."durin% the 0eriod from t NI the in0ut )olta%e isne%ati)e and freewheelin% diode .Mis forward biased8 .M conducts to 0ro)ide continuouslcurrent in case of inducti)e loads8 5n the ne%ati)e half'ccle of in0ut )olta%e T" is forward

biased and tri%%erin% of T"at t G N I will re)erse bias .Mand is turned !!8 Load isconnected to su00l throu%h T"and .18

The con)erter has a better 0ower factor due to the freewheelin% diode and iscommonl used in a00lications u0 to 1*@9 where one Auadrant o0eration is acce0table8

The half controlled brid%e has the inherin% freewheelin% action and analsis is moreor less the same with or without a freewheelin% diode is connected across the load8 5n

0ractical it is alwas ad?ustable to 0ro)ide a freewheelin% diode in a half'controlled con)erter

so that the commutation of SCRs is assumed inducti)e loads8PROCEDURE

1; Connections are made as 0er the circuit dia%ram8"; Switch on the 0ower circuit and net switch on tri%%er circuit8; /ow )ar the firin% an%le and note down the readin%s of the out0ut )olta%e8+; bser)e the half'controlled wa)eform in CR*; Perform the same o0erations with RL loads8; $)oid usin% two CR 0robes as there is a 0roblem of short circuit8

PRECAUTION

1; $)oid loose connections"; 9hile turnin% on first turn on the con)erter and then turn on the firin% circuit8; 9hile turnin% off first remo)e the firin% the 0ulses and then turn off the con)erter8



28/67


CIRCUIT DIA!RAMS

MODE" !RAPHS



29/67


TABU"AR FORMR+"OAD



30/67


Se-alNo.

F-ngAngle()

O02


31/67


1; Modified series in)erter2) .8C8re%ulated 0ower su00l; Rheostat *6D"$+; Cathode ra oscillosco0e*; Connectin% wires

THEOR 5n)erters in which commutatin% com0onents are 0ermanentl connected in serieswith the load are called series in)erter 8The series circuit so formed must be under dam0ed8$s the current attains Hero )alue due to the nature of series circuit, series in)erters areclassified as self'commutated For; load commutation in)erter8

These in)erter o0erate at hi%h freAuencies F"66hHto1667hH; the siHe ofcommutation com0onents is small these in)erters are used in induction heatin% fluorescentli%htin% etc8 Two SCRs T1and T" are turned on a008 so that oD0 )olta%e of desired freAuenccan be obtained when T1/ T"!!8 Current P starts buildin% u0, after reachin% some 0ea7

)alue decas to Hero at one 0oint8 so that the load current tends to re)erse SCRT1is !! afterT"turns / at 0oint B ca0acitor be%ins to dischar%e and load current in re)ersed directionbuilds u0 to some )e 0ea7 )alue and the 0rocess re0eats at 0oint c8T1a%ain turned and the0rocess re0eats8 5n this manner .C is con)erted into $C with hel0 of series in)erter8

PROCEDURE1; Connections are made as 0er the circuit dia%ram2) /ow connect tri%%er oD0 from the firin% circuit to %ate and cathode at SCRsT1&T"; Connect .C in0ut from a 6>D"$ re%ulated 0ower su00l+; Switch / the in0ut .C su00l b means of a00lin% tri%%erin% 0ulses to the sets*; Re0eat the e0eriment for different freAuencies and obser)e the )olta%es wa)e forms

across the load8

TABU"AR FORM

S8/ >.CF>; T/ Fms; !reAuenc F3H; >L$.F>;

CA"CU"ATIONS

Resonant freAuenc frG 12!C



32/67


CIRCUIT DIA!RAM :

MODE" !RAPH S

RESU"T



33/67


#I#A 5UESTIONS

1; 9hat is an in)erter"; 9hat should be the condition between R'L'C com0onents; 9hat t0e of commutation is em0loed to turn off SCR+; Can two thristors be in / condition at the same time*; 9hile a ca0acitor is char%in% the other ca0acitor dischar%es8 =ESD/

. PSPICE ANA"SIS OF SIN!"E PHASE FU"" CON#ERTER ;

AC #O"TA!E CONTRO""ER



34/67


PSPICE ANA"SIS OF SIN!"E PHASE FU"" CON#ERTER 8ITH R"E

"OAD

AIMTo analHe the sin%le 0hase full con)erter with RLE Load8

SIMU"ATION TOO"S RE5UIRED

PC with PSP5CE Software8

CIRCUIT DIA!RAM

5

8

R

1 0 O H

3 4

7

V s

L

1 0 0 M

E

1 0 0 V

9

1

2

0

X T 1

X T 2

X T 3

X T 4

6

SPECIFICATIONS

Sinusoidal in0ut: >!!G 6>, >$MPLG 1482>, !RE G *6 3H8T1and T": >1G 6>, >"G 166>, T.G 8+us, TRG T!G 1ns, P9 G 166us, PER G"6ms8 Tand T+: >1G 6>, >"G 166>, T.G 18+us, TRG T!G 1ns, P9 G 166us,PER G "6ms8 !irin% circuit: R#G *6 U, >V, >=G 6>, RTG 1 U, CTG 16uf, R/ G6861"*, R!!G 16EI*, >/G 68*>, >!!G 6>, 5SG "8"E'1*, B> G 1-66>, TT G 6 sec8

THEOR

Sin%le 0hase full controlled con)erters are thristors based circuits which

con)ert fied alternatin% )olta%e into )ariable direct )olta%e chan%e in ma%nitude8The circuit consists to four thristors connected in in brid%e manner8

PROCEDURE



35/67


FOR ANA"SIS USIN! PRO!RAM

1* 9rite the 0ro%ram in a new tet file in PS0ice $.82* Sa)e the file usin% the notation file name 8cir88 $cti)ate the file b o0enin% it8

+8 Run the simulation 0rocess usin% blue button8*8 B clic7in% $dd Trace icon, %et the reAuired wa)eform8

PRO!RAM

823 R"E "oad

S5#LE'P3$SE !ERTER C5RCS1 1 " S5/F6 1482> *63W;R1 2 - 163ML1 - 4 166M3

>.C 4 6 .C 166>>#1 2 P 8+= * 2 .C 6>.T 2 " .M.RT " 13MCT " 16V > = 6 *6 118M.EL SM. >S95TC3FR/G6 861"* R!!G16EI* >/G6 8*>>!!G6>;8M.EL .M. .F5SG"8"E'1* B>G1-66 TTG6;8E/.S SCR8TR$/ 1


36/67


Time

0s 10ms 20ms 30ms 40ms 50ms 60ms

V(1,2)

-200V

-100V

0V

100V

200V

OUTPUT 8A#EFORM

Time


V(7)

-100V

0V

100V

200V

300V

RESU"T

#I#A 5UESTIONS

18 9hat is our conclusion about this e0eriment"8 Briefl e0lain the o0eration of sin%le 0hase full con)erter88 #i)e the sntaes for definin% the followin% elements:

i8 Pulse )olta%eii8 Sinusoidal )olta%eiii8 Thristori)8 Switch

18 E0lain about the command XS


37/67


PSPICE ANA"SIS OF SIN!"E PHASE AC #O"TA!E CONTRO""ER

8ITH R"E "OAD

AIMTo analHe the sin%le 0hase full con)erter with RL and RLE Loads8



CIRCUIT DIA!RAM

X T 1

X T 2

V S

V D

L 1

R 1

SPECIFICATIONS

Sinusoidal in0ut: >!!G 6>, >$MPLG 1482>, !RE G *6 3H8T1: >1G 6>, >"G 166>, T.G 8+us, TRG T!G 1ns, P9 G 166us, PER G"6ms8T": >1G 6>, >"G 166>, T.G 18+us, TRG T!G 1ns, P9 G 166us, PER G"6ms8!irin% circuit: R#G *6 U, >V, >=G 6>, RTG 1 U, CTG 16uf, R/ G 6861"*, R!!G16EI*, >/G 68*>, >!!G 6>, 5SG "8"E'1*, B> G 1-66>, TT G 6 sec8

THEOR

$c )olta%e controllers are thristors based de)ices which con)ert fiedalternatin% )olta%e directl to )ariable alternatin% )olta%e without a chan%e infreAuenc8 The circuit consists to two thristors connected in anti'0arallel8

PROCEDURE


1* 9rite the 0ro%ram in a new tet file in PS0ice $.82* Sa)e the file usin% the notation file name8cir88 $cti)ate the file b o0enin% it8+8 Run the simulation 0rocess usin% blue button8

*8 B clic7in% $dd Trace icon, %et the reAuired wa)eform8



38/67


PRO!RAM

S5#LE'P3$SE $C >LT$#E C/TRLLER C5RCS1 1 6 S5/F6 1482> *63W;R1 " 163ML1 - 16M3>.C - 6 166>>#1 + " P 8+ = 6 *6 118M.EL SM. >S95TC3FR/G6861"* R!!G16EI* >/G68*>>!!G6>;8M.EL .M. .F5SG"8"E'1* B>G1-66 TTG6;

8E/.S SCR8TR$/ 1


39/67


OUTPUT 8A#EFORM

Time


V(2)

-200V

-100V

0V

100V

200V

RESU"T

RE#IE8 5UESTIONS

18 9hat is !ull Con)erter

"8 Briefl e0lain about sin%le 0hase $C )olta%e controller3* 9hat is the command for callin% a sub0ro%ram in Ps0ice+8 E0lain about the command XS


40/67


8

1*PSPICE ANA"SIS OF RESONANT PU"SE

COMMUTATION CIRCUIT AND BUC& CHOPPER

PSPICE ANA"SIS OF RESONANT PU"SE COMMUTATION CIRCUIT

AIMPs0ice analsis of resonant 0ulse commutation circuit8



CIRCUIT DIA!RAMS

Resonant Pulse Commutation Circuit

0

3

R 11 0 M E G

L m5 M H

T 1

7

T 3

1 1

V g 3

C

3 1 . 2 U F

T 2

4

8

V g 1R 2

1 0 M E GV g 2

1

V x0 V9

R 31 0 M E G

2

D m

R s

7 5 0 o h m s

D 1

R m0 . 5

1 0

C s

0 . 1 U F

V s

L

6 . 4 U H

5

6

V

0 V

SPECIFICATIONS

>SG "66>, for diode .M: 5SG1E'"* B>G1-66,>%1: >1G 6, >"G 166>, T.G 6, TRG T!G 1us, P9 G 68+ms, PER G 1ms8>%": >1G 6, >"G 166>, T.G 68+ms, TRG T!G 1us, P9 G 68ms, PER G 1ms8>%: >1G 6, >"G 166>, T.G 6, TRG T!G 1us, P9 G 68"ms, PER G 1ms85nternal thristor circuit: switch: R/G681, R!!G16EI, >/G16>, >!!G*>,diode: 5SG1E'"*, B>G166668 Transient res0onse s0ecifications: 68*


41/67


PRO!RAM

RES/$/T P

8E/.



42/67


PROCEDURE


1* 9rite the 0ro%ram in a new tet file in PS0ice $.82* Sa)e the file usin% the notation filename8cir88 $cti)ate the file b o0enin% it8+8 Run the simulation 0rocess usin% blue button8*8 B clic7in% $dd Trace icon, %et the reAuired wa)eform8

MODE" 8A#EFORMS

# (1, %)

Time

1.4ms 1.6ms 1.8ms 2.0ms 2.2ms 2.4ms 2.6ms 2.8ms

V(1,2)

-1.0KV

-0.5KV

0V

0.5KV

1.0KV

I(C)

Time


I(C)

-2.0KA

-1.0KA

0A

1.0KA

2.0KA



43/67


I(#X)

Time


I(VX)

-200mA

-100mA

0A

100mA

200mA

RESU"T

RE#IE8 5UESTIONS

18 9hat is resonant 0ulse commutation"8 9hat is carrier si%nal8 9hat is the 0rocedure to define a switch and diode4* 9hat is sub circuit

*8 9hat is our conclusion after doin% the analsis



44/67


PSPICE ANA"SIS OF BUC& CHOPPERAIMTo analHe Buc7 cho00er usin% PSP5CE8


PC with PSP5CE Software8CIRCUIT DIA!RAM

R !

2 5 0 O H M S

0

C "# . 3 3 U F

T 1

V x 0 VV g

L

4 0 . $ 1 U H

D m

V

0 V

R3 O H

V s1 1 0 V

L "

6 # 1 . # 2 U H

SPECIFICATIONS

>#: >1G 6>, >"G "6>, T.G 6, TRG T!G 681ns, P9 G "28"-us, PER G *6us8 !orCe, 5C G 6>8 !irin% circuit: R/ G 681, R!!G 16EI-, >/G 16>, >!!G *>, !or.T: 5SG e'"*, B> G 1666>8 !or .M, 5SG "8"e'1*, B> G 1666>, TT G 68

THEOR

$ cho00er is a hi%h s0eed on For; off switch8 5t connects source to load and

disconnects the load from source at a fast s0eed8 5f the a)era%e out0ut )olta%e >6is less

than the in0ut )olta%e >Si8e, >6O >S, then the corres0ondin% cho00er circuit is calledste0'down cho00er8

The 0rinci0le of o0eration is as follows durin% the 0eriod in which

transistor FTr ; is /, the load )olta%e is eAual to source )olta%e >s8 .urin% the inter)al

in which Tr is off, the load current flows throu%h the free'wheelin% diode !. and load

)olta%e is therefore Hero durin% T off8 5n this manner, a cho00er .C )olta%e is 0roduced

at the load terminals8


1 V


45/67


6 SV V=

9here

G dut ccle G / time of transistorFT/; D Total TimeFT;

3ence, T G constant and VsG constant

Therefore, The load )olta%e >6can be controlled b )arin% dut ccle , the load

)olta%e is inde0endent of load current8

PRO!RAM

BS 1 6 .C 116>>= 1 " .C 6>># 2 P


46/67


PROCEDURE


1* 9rite the 0ro%ram in a new tet file in PS0ice $.8

2* Sa)e the file usin% the notation filename8cir88 $cti)ate the file b o0enin% it8+8 Run the simulation 0rocess usin% blue button8*8 B clic7in% $dd Trace icon, %et the reAuired wa)eform8

MODE" 8A#EFORMS

INPUT ; OUTPUT 8A#EFORMS

Time

1.50ms 1.51ms 1.52ms 1.53ms 1.54ms 1.55ms 1.56ms 1.57ms 1.58ms 1.59ms

V(3) V(1)

-40V

0V

40V

80V

120V

RESU"T

RE#IE8 5UESTIONS

18 9hat is a cho00er"8 9hat is the snta for definin% an element8 9hat is the 0rocedure to define a switch and diode4* 9hat is sub circuit*8 9hat is our conclusion after doin% the analsis



47/67


1.SIN!"E+PHASE DUA" CON#ERTERAIM

To construct a sin%le 0hase dual con)erter and to a00l re)ersible )olta%e to load8

APPARATUS

1) $uto transformer"; 5solation transformer; .ual con)erter 0ower and firin% module+; Loadin% rheostat'*6D-$*; .i%ital millimeters; Cathode ra oscillosco0e2; Patch cards

THEOR

.ual con)erter consists of two con)erters both are connected to the same load8 The0ur0ose of a dual con)erter is to 0ro)ide a re)ersible .C )olta%e to the load8 5t is needed for.C motor dri)es where re)ersal is reAuired8 .ual con)erter 0ro)ides four Auadrant o0erationshence the name dual8 The two modes of o0erations are the non'circulatin% current mode andcirculatin% current mode8 5n the former onl one brid%e is tri%%ered8 9hen re)ersal of out0ut)olta%e is reAuired, the firin% 0ulses for concretin% brid%e are sto00ed and second brid%e is%ated8 Since the conductin% SCRs in the first brid%e will turn off onl when the current %oesto Hero, a small dead time must be allowed before the second brid%e is %ated otherwise: the$C in0ut will be shorted throu%h the two brid%es8

5n the circulatin% current mode, both brid%e are %ated simultaneousl, one o0eratin%in the rectifin% mode and the other in the in)ertin% mode to a)oid short circuits8 Thisscheme reAuires full controlled brid%es8 The internal )olta%e of rectifier is hi%her and that ofin)erter is lower than the out0ut )olta%e8 This can be done b two was 1; b 7ee0in% su00l)olta%e > constant and firin% brid%e 1 FP' con)erter; at and brid%e " F/'con)erter; at FN';8B 7ee0in% firin% an%le constant and maintainin% su00l )olta%e at rectifier brid%e %reaterthan su00l )olta%e at in)erter brid%e8

The dual con)erters can be o0erated with or without a circulatin% current8 5n this case

of o0eration without circulatin% current, onl one con)erter o0erates at a time and carries theload current and the other con)erter is com0letel bloc7ed b inhibitin% %ate 0ulses83owe)er, the o0eration with circulatin% current has the followin% ad)anta%es8

1; The circulatin% current maintains continuous conduction of both con)erters o)er thewhole control ran%e, inde0endent of the load8

"; Since one con)erter alwas o0erates as a rectifier and the other con)erter o0erates asan in)erter, the 0ower flow in either direction at an time is 0ossible8

; Since both con)erters are in continuous conduction the time res0onse for chan%in%from Auadrant to another is faster8



48/67


PROCEDURE



49/67


DUA" CON#ERTER IN NON+CIRCU"ATOR CURRENT MODE

I) P+Con4e-2e- ON ; N+Con4e-2e- OFF

1; Connections are made as 0er the circuit dia%ram8

"; Connect rheostat at *6D-$8; Connect CR across load8+; $00l $C in0ut )olta%e usin% isolation transformer85) Made P'con)erter / & !! the /'con)erter8; >ar firin% an%le obser)e load )olta%e wa)eforms on CR87) /ote down load )olta%e in ste0s b )arin% firin% an%le usin% multimeter8

Sl.NOF-ng angle n deg-ee

(N+*on4e-2e-) +"oad 4ol2age

#"(DC)In 4ol2

1 66

" 66

II) N+Con4e-2e- ON ; P+Con4e-2e- OFF

1; Connections are made as 0er the circuit dia%ram8"; Connect rheostat at *6D-$8; Connect CR across load8+; $00l $C in0ut )olta%e usin% isolation transformer8

*; Made /'con)erter / & P'con)erter !!8; >ar firin% an%le obser)e load )olta%e wa)eforms on CR87) /ote down load )olta%e in ste0s b )arin% firin% an%le usin% multimeter8

Sl.NOF-ng angle n deg-ee

(N+*on4e-2e-) +"oad 4ol2age

#"(DC)In 4ol2

1 66

" 66

!irin% an%le of /'con)erter G Y firin% an%le of P'con)erter

G Y

III) DUA" CON#ERTER IN CIRCU"ATOR CURRENT MODE

1; Connections are made as 0er the circuit dia%ram8"; Connect rheostat at "D1$8; Connect CR across load8+; $00l $C in0ut )olta%e usin% isolation transformer8 Sa 6> ran%e8

*; Made /'con)erter / & P'con)erter /8; >ar firin% an%le, obser)e load )olta%e wa)eforms on CR8



50/67


7) /ote down load )olta%e in ste0s b )arin% firin% an%le usin% multimeter8

Sl.No.9-ng angle n

deg-ee ( P+

Con4e-2e-)

F-ng angle +n deg-ee (N+

*on4e-2e-)

"oad 4ol2age #"

(DC) n 4ol21 1-66 66

" 1*66 66

1"66 66

+ 466 466

* 66 1"66

66 1*66

2 66 1-66

RESU"T

Sin%le 0hase dual con)erter is constructed and its 0erformance is studied8



51/67


1.SIN!"E PHASE IN#ERTER 8ITH P8M CONTRO"

AIMPS0ice analsis of sin%le 0hase in)erter with P9M control8



CIRCUIT DIA!RAM

D 4

5

1 2D 1

T 2

V 0 V

9

T 3R g 1

R

2 . 5 O H M S

1

7

V x

0 V

T 4

1 3

R g 4

2

4

6V s1 0 0 V

8

T 1

D 2

R g 3

1 1

L

1 0 M H

0

1 4 1 0

R g 2

D 3

3

P+ -enerat(r

R % &2 M E G

R 4

1 0 0 ' O H M S

4

2

V (

1

C o1 0 )

R 2

1 +

6

R o7 5 O H M S

0

V ,

3

R 1

1 +

5



52/67


Carrier and .e/eren'e #ignal#

0

R ( 12 M E G

1 71 5

V ,V ( 1 V ( 3R ( 32 M E G

1 6

R ,2 M E

SPECIFICATIONS

>R: >1G *6>, >"G 6>, T.G 6, TRG T!G -8us, P9 G 1ns, PER G182us8>C1: >1G 6>, >"G '6>, T.G 6, TRG T!G 1ns, P9 G -8us,PER G 182us8 >C: >1G 6>, >"G '6>, T.G -8us, TRG T!G 1ns,P9 G -8us, PER G 182us8!irin% circuit: R#G *6 U, >V, >=G 6>, RTG 1 U, CTG 16uf, R/ G 6861"*, R!!G16EI*, >/G 68*>, >!!G 6>, 5SG "8"E'1*, B> G 1-66>, TT G 6 sec8 !or .t,

5SG e'1*, B> G 1666>8

THEOR

.c to ac con)erters are 7nown as in)erters8 The function of an in)erter isto chan%e a dc in0ut )olta%e to a smmetrical ac out0ut )olta%e of desired ma%nitudeand freAuenc8 The out0ut )olta%e could be fied or )ariable at a fied or )ariablefreAuenc8 $ )ariable )olta%e can be obtained b )arin% the in0ut .C )olta%e andmaintainin% the %ain of in)erter constant8 n the other hand, if the dc in0ut )olta%e isfied and it is not controllable, a )ariable out0ut )olta%e can be obtained b )arin% the%ain of the in)erter, which is normall accom0lished b 0ulse width modulation FP9M;control within in)erter8 The in)erter %ain ma be modified as the ratio of the ac out0ut)olta%e to dc in0ut )olta%e8

The out0ut )olta%e wa)eforms of ideal in)erters should be sinusoidal83owe)er, the wa)eforms of 0ractical in)erters are non'sinusoidal and contain certainharmonics8 !or low and medium 0ower a00lications, sAuare wa)e or Auassi sAuarewa)e )olta%es ma be acce0tableZ and for hi%h'0ower a00lications, low distortedsinusoidal wa)eforms are reAuired8 9ith the a)ailabilit of hi%h's0eed 0ower

semiconductor de)ices, the harmonic contents of out0ut )olta%e can be minimiHed orreduced si%nificantl b switchin% techniAues8



53/67


PRO!RAM

P>R 12 6 P 6> 6 -8C 1 6 PG1-66> TTG6;VT1 " 2 .CSCR

VT" 6 4 6 .CSCRVT " 11 .CSCRVT+ 6 1 6 .CSCR.S


54/67


R! * 166@R 2*C + 16P!E1 + 6 * "EI*.E/.S P9M.TR$/ 16


55/67


C"ASS A COMMUTATION

AIMTo ri% u0 turn off circuit for SCR b CL$SS'$ commutation8

APPARATUS1; !orced commutation stud 7it"; .C re%ulated 0ower su00l 6'6>D"$; Connectin% wires+; Cathode ra oscillosco0e

THEORThe current re)ersin% 0ro0ert of load will force the de)ice commutation8 L,C,R

)alues are chosen such that the circuit is under dam0ed8 Since the commutation elementscarr load current on a continuous basis their ratin%s are %enerall hi%h8 !or low freAuenco0eration, lar%e )alues for L and C are reAuired8

CIRCUIT DIA!RAM ; MODE" !RAPHS

PROCEDURE

1; Ma7e the connections as 0er the circuit dia%ram82) Connect the tri%%er out0ut T1to %ate and cathode of SCR T18



56/67


3) Switch / the .C su00l to 0ower circuit and obser)e the )olta%e wa)eformacross the load b )arin% the freAuenc 0otentiometer8

+; .ut ccle 0otentiometer is of no use in this e0eriment85) Re0eat the same for different )alues of L, C , R8

TABU"AR FORM:

RESU"T

#I#A 5UESTIONS1; 9hat is the other name for this commutation"; 9hat condition should be satisfied for R'L'C elements; Mention an a00lication of class'$ commutation8


S.NO. TON() TOFF()DUT CC"E

TONTT$TONGTOFF

FRE5UENC(H)OUTPUT

#O"TA!E#O(#)


57/67


C"ASS+B COMMUTATION

AIM To stud CL$SS'B commutation circuit8

APPARATUS 1; !orced commutation stud 7it"; .C re%ulated 0ower su00l 6'"+>D"$; Connectin% wires+; Cathode ra oscillosco0e*; Rheostat *6 D"$

THEOR

5n this t0e of commutation re)erse )olta%e is a00lied to the SCR b the o)erswin%in% of under dam0ed circuit connected across the SCR8

$ ca0acitor char%e u0 to the su00l )olta%e before the tri%%er 0ulse is a00lied to the%ate8 9hen the SCR is tri%%ered, a load current flows throu%h the eternal circuit and a 0ulseof current throu%h LC circuit and SCR is in o00osite direction8 This rheostat current tends toturn !! SCR8

CIRCUIT DIA!RAM ; MODE" !RAPH

PROCEDURE 1; Ma7e the connections as 0er the circuit dia%ram8



58/67


2) Connect the tri%%er 0ulses to SCR1; Switch / the .C su00l and obser)e the )olta%e wa)eform across the load b

)arin% the freAuenc 0otentiometer8+; Re0eat the same for different )alues of R, L and C8 Model wa)eforms are drawn

b obser)in% the load )olta%e usin% CR8

TABU"AR FORM

RESU"T

#I#A 5UESTIONS

1; 9hat is the other name of this commutation"; 5s it current commutation or )olta%e commutation; 9hat should be the condition for R'L'C com0onents


S.NO. TON() TOFF()

DUTCC"E

TONTT$TONGTOFF

FRE5UENC(H)OUTPUT

#O"TA!E#O(#)


59/67


C"ASS+C COMMUTATION

AIM To ri% u0 the T


60/67


PROCEDURE1; Ma7e the connections as 0er the circuit dia%ram82) Connect T1and T"from firin% circuit to %ate and cathode of SCR T1and T"83) bser)e the wa)eforms across R1, R", and C b )arin% freAuenc and also dut

ccle 0otentiometer8+; Re0eat the same for different )alues of C and R8

TABU"AR FORM:

RESU"T

#I#A 5UESTIONS

1; 9hat is the other name of this commutation 9h"; 5s it current commutation or )olta%e commutation; 5s there a chance for both the thristors to be in / condition


S.NO. TON() TOFF()

DUTCC"E

TONTT$TONGTOFF

FRE5UENC(H)

OUTPUT

#O"TA!E#O(#)


61/67


C"ASS+D COMMUTATION

AIM

To ri% u0 the turn !! for SCR b usin% Class'. commutation8APPARATUS

1; !orced commutation stud 7it"; .C re%ulated 0ower su00l 6'"+>D"$; Connectin% wires+; Cathode ra oscillosco0e*; Rheostat *6 D"$

THEORThis t0e of commutation is 0o0ular due to the desi%n fleibilit8 These are ma be

cho00ers and in)erters under this class8T"must be tri%%ered first in order to chan%e ca0acitor C8 T" is commutated !!owin% to lac7 of current8 9hen T1 is tri%%ered current flows in two 0aths, load currentthrou%h R1and commutatin% current throu%h C, T1, L nad .8 the char%e on the ca0acitor isre)ersed and held with the hold !! diode .18 $t an desired instant T"ma be tri%%eredwhich then 0laces C across T1)ia T"and T1is turned !!8




62/67


PROCEDURE1; Ma7e the connections as 0er the circuit dia%ram2) Connect T1and T"%ate 0ulses from firin% circuit to the corres0ondin% SCRs in

the 0ower circuit8; 5nitiall 7ee0 the tri%%er to !! 0osition to initiall char%e ca0acitor8

+; /ow switch / the tri%%er out0ut switch and obser)e the )olta%e wa)eform atdifferent freAuencies of cho00in% and also at different dut ccles8*; Re0eat the e0eriment for different )alues of load resistance, L and C8

TABU"ARFORM

S.NO. TON() TOFF()

DUTCC"E

TONTT$TONGTOFF

FRE5UENC(H)

OUTPUT#O"TA!E

#O(#)

RESU"T

#I#A 5UESTIONS

1; 9hat is other name of this commutation"; 5s it current commutation or )olta%e commutation; 9hat is current commutation and )olta%e commutation+; Mention an a00lication of class'. commutation8

C"ASS E COMMUTATION



63/67


AIMTo ri% u0 turn !! circuit for SCR b class'E commutation with an eternal source of

0ulse for commutation8

APPARATUS

1; !orced commutation stud 7it with transistor"; .C re%ulated 0ower su00l 6'"+>D"$ two numbers; Connectin% wires+; Cathode ra oscillosco0e*; Rheostat *6 D"$

THEOR5n class'E for turn !!, re)erse )olta%e is a00lied to load carrin% thristor from an

eternal source across as in series with the conductin% SCR8 The turn !! time of SCR issmaller than the width of the 0ulse8 The conductin% 0eriod of SCR is from the instant of

a00lication of tri%%erin% 0ulses till the eternal turn !! )olta%e is a00lied8 9hen SCR istri%%ered load current flows, this connects the ne%ati)e auiliar )olta%e to the SCR to turn it!!8


PROCEDURE1; Ma7e the connections as 0er the circuit dia%ram8

2) Connect the tri%%er out0ut T1from the firin% circuit to the SCR83) Connect T"to the SCRs base and emitter 0oints8



64/67


+; Switch / the .C su00l and eternal .C su00l85) Switch / the tri%%er out0ut and obser)e the wa)eforms across the load8; Re0eat the same b )arin% freAuenc and dut ccle8

TABU"AR FORM

S.NO. TON()TOFF()

DUTCC"E

TONTT$TONGTOFF

FRE5UENC(H)OUTPUT

#O"TA!E#O(#)

RESU"T

#I#A 5UESTIONS

1; 9hat is other name for this commutation 9h"; E0lain the use of a transistor in this commutation8

1.SIN!"E PHASE CC"OCON#ERTER

AIM:To stud the 0erformance of sin%le 0hase Cclo con)erter8

APPARATUS

1) Cclo con)erter 0ower circuit



65/67


"; Microcontroller based firin% unit; Rheostat *6D"$+; 5nductor *6Mh*; Cathode ra oscillosco0e; Connectin% wires

THEOR

$ Cclocon)erter is a t0e of 0ower controller in which an $C )olta%e at su00lfreAuenc is con)erted directl to an $C )olta%e at load freAuenc8

There are mainl two confi%urations for this t0e of Cclocon)erter8 The are1; Centre ta00ed TD! confi%uration"; Brid%e confi%uration5n Centre ta00ed transformer confi%uration, durin% the first half ccle when 0oint P is

0ositi)e and 0oint is ne%ati)e SCR P1bein% in conductin% mode is %ated8 The current flowsthrou%h I)e 0oint P, SCR P1,load and the )e 0oint 8 5n ne%ati)e half ccle, when is

0ositi)e and 0 is ne%ati)e 8SCR 01 is automaticall turned off and SCR 0" is tri%%eredsimultaneousl 0ath for current flow in this confi%uration or condition will be from 0ositi)e0oint 8SCR 0",load and ne%ati)e 0oint Xo8 .irection of flow of current throu%h the loadremains the same as in the 0ositi)e half ccle 8/et moment a%ain 0 becomes 0ositi)e and

becomes ne%ati)e, thus SCR 0" is automaticall line commuted SCR 01 is %atedsimultaneousl8 The current 0ath %ain becomes a%ain the 0re)ious case when SCR 01 wasconductin% 8Thus it is seen that the direction of current throu%h the load remains in all three

0hase circuits

PROCEDURE1; Switch on the main su00l of the firin% circuit and obser)e test 0oints and tri%%er

out0uts b chan%in% freAuenc di)ision and b )arin% the firin% an%le8"; Ma7e sure that firin% 0ulses are 0ro0er before connectin% to the 0ower circuit8; Ma7e the connections as 0er the circuit dia%ram8+; $lso connect )oltmeter and ammeter in the 0ower circuit8*; Connect the firin% 0ulses from the firin% circuit to res0ecti)e SCRs in the 0ower

circuit8; bser)e the wa)eforms in the CR82; Before turnin% off first remo)e the firin% 0ulses and then switch off the circuit8

CIRCUIT DIA!RAM 8ITH R ; R" "OADS



66/67


MODE" !RAPH

TABU"AR FORM

R+"OAD



67/67


S.NOF-ng

Angle ()

FRE5UENC 1 FRE5UENC 6 FRE5UNC >

#DC(#) #RMS(#) #DC(#) #RMS(#) #DC(#) #RMS(#)

R"+"OAD

S.NOF-ng

Angle ()

FRE5UENC(H) FRE5UENC 6 FRE5UNC >

#DC(#) #RMS(#) #DC(#) #RMS(#) #DC(#) #RMS(#)

RESU"T

#I#A 5UESTIONS

1) 3ow man $C')olta%e controllers are reAuired in a Cclocon)erter 82) 9hat is the difference between a Cclocon)erter and an $C )olta%e controller3) 9hat t0e of commutation is em0loed in cclocon)erter

60707871 pe s lab manual student copy

Documents