1  

Hello, inoff snubbspike acrthe thyrisand how The secotrigger thfrom thetransform (Refer Sl

It is a spsignals thoperationdifferent.transform

n my last claber. These cross the SCRstor. Now, wdo we limit

ond point thhe thyristor, e control cirmer.

lide Time: 2

pecial type ohat is transmn of this tran. See, in a

mer, ferrite c

Dep

India

ass we discucircuits are rR. How did wwe know that

the voltage

hat we discularge numb

rcuit to the

:25)

of transformemitting fromnsformer is s50 hertz traore is used.

Powe

Prof. B

partment of

an Institute

L

ssed the neerequired to we limit dr bt the currentspike across

ussed was aber of high fgate? We u

er. Why it ism one side same as thatansformer, w

er Electronic

B.G. Fernan

Electrical E

of Technolo

ecture - 6

ed for snubbprotect the by dt? We ct through thes the SCR? W

a high frequfrequency puuse a pulse

s a special tyto the anotht of a 50 her

we use a lam

cs

ndes

Engineering

ogy, Bomba

ber circuits,device again

connected a e inductor caWe use a RC

uency pulse ulses. How transformer

ype? The sigher side is rtz transformminated cor

g

ay

the turn on nst dr by dtsmall induc

annot changC network.

pattern is do we trans. See here,

gnals or the very high.

mer. Only thre whereas a

snubber andt and the vo

ctor in seriese instantane

recommendsmit these si

this is the

frequency oThe princip

he type of coa high frequ

d turn oltage s with ously

ed to ignals pulse

of the ple of ore is uency

2  

(Refer Sl

Ferrite cofrequencytop it is wthe numbpower cir Now, whare differslow devone is thfrequency

lide Time: 3

ore, of coursy applicationwritten, 1 isber of turns rcuit from th

hat are the drent types of

vices, they arhe inverter y application

:10)

se this is a bn. So, there to 1, it impin the secon

he control cir

different typef SCR’s alsore used in thgrade SCR.n. So, here is

bigger ferriteare 4 termin

plies that thendary windinrcuit.

es of SCR’so. One of the circuit whe. So, these s the module

e core, a solinals, primarye number of ng. So, this i

s? We had dhem is see herein the freare fast dev

e that has tw

id ferrite cory winding an

turns in theis a pulse tra

different typhere, the conequency coulvices, fast d

wo thyristors.

re, these are nd the seconde primary wiansformer u

pes of diodesnverter gradeld be 50 hertdevices so s.

suitable fordary windinginding is sam

used to isolat

s. Similarly e SCR. Thestz and the sesuitable for

r high g. On me as te the

there se are econd

high

3  

(Refer Sl

(Refer S

Inverter gvolts. 2 terminalscathode ohere cathflows.

lide Time: 4

Slide Time: 5

grade thyristhyristors, s

s, 3 power tof another. hode and ga

:46)

5:02)

tor, the ratinsee they areterminals haSee, these 2

ate. See the

ng of each the connected ave been br2 terminals fcontact area

hyristor is 4in this fash

ought out, afor supplyina, this anode

45 ampere anhion. See, tanode of on

ng the gate se, cathode s

nd the voltathese are thne, a commosignal, cathoso generally

age rating ishe 2 thyristoon point anode and gate

the load cu

1200 ors, 3 nd the e, see urrent

4  

So, see tand cathoelegant it (Refer Sl

So, that popularitrating of (Refer Sl

the surface aode. A smallt looks.

lide Time: 6

is why I toty of powerthis thyristo

lide Time: 7

area that is al current is f

:32)

ld you in mr electronicsor is given he

:05)

available whflowing from

my introduct is the advaere, I copied

hereas, see thm the gate an

ive lecture tances in po

d from, I dow

he surface and it is moun

that the oneower semicownloaded thi

area that is anted on a he

e of the maionductor techs data sheet

available forat sink. See,

in reason fohnology. Sofrom their s

r gate , how

or the o, the ite.

5  

See, 46Fis only 0repetitiveRMS cursurge cur1300 amrequired (Refer Sl

See, the See, the current, rSee, the milli ampare the so So, that ireverse bregulatorvoltage asingle phSo definthyristorswas deve

. F stands fo0 8, the volte peak, forwrrent rating, rrent rating,

mperes and ato determine

lide Time: 00

critical rate gate trigge

rating is 45 gate trigger peres. See, Iome of the im

is about the biased, it doers, see, I havapplied to thhase AC macnitely, I nees separately eloped in 196

or first 0 8 dotage rating

ward off state120 ampere1300 ampe

another impe the fuse. 84

0:08:41 min

of rise of onr current IG

amperes. Suvoltage 1.4

I told you thmportant par

conventionaes not conduve a 50 herthe machine chine. So, itd to connecin anti paral64 by genera

ot dot till 13is 800 voltse and reverses whereas,res. I explai

portant para450 amperes

n)

n state curreGT 150 milliurge current

volts, holdihat latching rameters of t

al thyristor wuct. What if tz AC supplor voltage a

t requires anct 2 thyristollel, there is al electric.

. This standss. If it is 13se voltages.the average ined to you,

ameter, I squs squared s.

ent, di by dt i amperes. Sis 1300 amp

ing current 2current is hithe thyristor

which conduinput is AC?y, 230 voltsapplied to thn AC supplyors in anti pa device ava

s for the vari3, the voltagThese are thon state cur what is suruared t cur

critical is 12So therefore

mperes, gate c250 milli amigher than th.

ucts when it ? Output is as and there ihe fan to va

y. I have an iparallel. No

ailable what

ious voltagege rating is he various vrrent is 45 arge current orrent, square

20 ampere fe, just see tcurrent is 15

mperes, latchhe holding c

is forward balso AC. Likis a regulato

ary the speedinput AC, oow, instead is known as

e ratings. See1300 volts.

voltages. Seeamperes. Seeor when it fed time rati

for micro secthe gain av50 milli amphing current current. So,

biased. Whenke, you knowor to regulatd. Fan is agutput is alsoof connecti

s the triac. A

e, if it See, e, the e, the flows, ng is

cond. erage peres. 1000 these

n it is w fan te the gain a o AC. ing 2

A triac

6  

(Refer Sl

It has a cparallel. am callinanode of in anti padevice, th So therefrespect toshould bebe triggecurrent w

lide Time: 1

complicated See, here is

ng this termif one is tied tarallel. So, nhere are 2 po

fore, how doo MT1 and se positive w

ered when Mwith respect t

1:18)

structure buthe connectiinals as MTto cathode onow it is goower termina

o I trigger? Aupplying a pith respect to

MT2 is negatito MT1.

ut then function, I have 11 and this asf another thying to be a bals but then t

A triac can positive gateo MT1 and aive with resp

tionally it is 1 thyristor, ths MT2. See, Iyristor. So, tbidirectionalthere is only

be triggerede current witha positive gapect to MT1

equivalent thyristor 2, gI cannot calthere are 2 el device. Re

y 1 gate term

d by see hereh respect to

ate current wand by a ne

to 2 thyristogates are tiedll anode and quivalent thy

emember, it minal.

e, making MMT1. See, I

with respect tegative curre

ors connectedd together G d cathode becyristor connis a bidirect

MT2 positiveI will repeat,to MT. It canent, negative

d anti and I cause

nected tional

e with , MT2

n also e gate

7  

(Refer Sl

So, here could beconductiothe sameregulatoreverythin (Refer Sl

So, thereconducto

lide Time: 13

are the chae thyristor 2on, forward e thyristor. rs. I told young is mounte

lide Time: 14

e is no poweor device, ha

3:43)

aracteristics. 2. These areblocking, foSo, these au, I showed

ed inside a sw

4:31)

er dissipationas three legs

2 thyristorse the VI chorward blockare the VI cd you a verywitch board.

n. That is wh. MT1 MT2

s connected haracteristicsking mode focharacteristicy elegant fan

hy it is so smand gate, th

in anti paras, negative ror another thcs. This trian regulator,

mall and I tohis are nothin

allel, say thyresistance, rhyristor, conacs are veryjust the kno

old you, thisng but a tria

yristor 1 andregional uns

nduction mody popular inob is brough

s is a power ac. This is a

d this stable de for n fan ht out

semi triac,

8  

this is a twhat is thyristor. (Refer Sl

The currpoint J1 avoltage ithis is thbecoming Now, thivoltage aconnectecurrent h See, this It has to breakdowconnectevoltage athis dv by See, I havby dt ratiWhy it iscurrent rswitchinggate sign

triac. So, triaa limitation .

lide Time: 15

rent has reveand J2, J1 ans applied acr

he turn off cg 0, the volta

is is for 1 thappearing acd in anti par

has become 0

apprehensioblock in th

wn voltage. Bd back to ba

appears acroy dt or in oth

ve written hing is less fos an ideal swrating, maxig or turn on

nal.

acs are also uof a triac?

5:29)

ersed, it has d J3 have atross the thyrcharacteristicage across it

hyristor, thecross the enrallel. Now, 0.

on was not the reverse diBut then in ack. So, wh

oss another ther words, tr

ere, it has leor the triac. witch? It requ

mum gate cperiod. Wh

used in light See, I am

attained a pttained the vristor and thics that we st is very diffe

e turn off chntire combinif this dv by

here when inirection as loa triac, there

hen a reversethyristor. Soriac has a les

ess time thanSo, now let

uires just a shcurrent is 1

hen the curre

t intensity com just showi

peak value,voltage blockis happens, tstudied for

ferent from 0

haracteristicsation across

y dt is high, i

n the case ofong as has ve are 2 thyrie voltage is o, the anothess time than

n the thyristome sum up harp pulse to50 milli am

ent is higher

ontrol, room ing you the

the reverse king capabilthis current dthe thyristor

0.

s. When it is the triac. Sit may trigge

f thyristor bevoltage acroistor, the triabeing applie

er thyristor ma thyristor to

or to recoverthe thyristoro turn on. If

mperes thatthan the lat

m temperaturee turn off ch

recovery culity. So therdecays at a vr. So, when

is turning ofSo, there is er another th

ecause thereoss it is less ac is equivaled to 1 of thmay get trigo recover its

r its blockingr. It is nearly

f 45 ampere tis required tching, you c

e control butharacteristic

urrent and arefore, a negvery fast rate

n this curren

ff there is a another thy

hyristor when

is only 1 de than the relent to 2 thyhem, the for

ggered becaus blocking po

g power or thy an ideal swthyristor, avonly during

can withdraw

t then of a

at this gative e. So,

nt has

high yristor n this

evice. everse yristor rward use of ower.

he dv witch. erage g this w the

9  

So, the gblock botas well apoint, debe turnedapplying of the thy (Refer Sl

So, this igate. To less than So, how modificaGTO whsignal, w

gate power reth positive a

as reverse, alvice is very d off by thea negative g

yristor.

lide Time: 20

is the limitaturn off thethe holding

do I make ations? Answhich is capabwe can turn o

equirement ias well as nelso high voltrugged, stur

applicationgate current

0:25)

ation, inabili thyristor, cucurrent. Till

this device wer is yes. Sble of turninff as well as

s very smallegative voltatage, high curdy but then

n for control through the

ity to turn ourrent flowil then it cont

which is cao, there is a

ng on as wels turn on a G

l compared tage. The ratinurrent devic

n what is thesignal at th

e gate. So se

ff by applicng through tinues to con

apable of tua device whall as turning

GTO. See her

to the powerng of this th

ces are availae limitation?he thyristor ee here, I hav

cation of a cit should be

nduct.

urning off that is known

off throughre, a gate tur

r rating of thhyristor is 12able in the m It has 1 limgate. It cannve summed

control signae reduced to

hrough gate?as the gate t

h gate. By aprn off thyrist

he thyristor. I200 volts formarket. The

mitation. It canot turn it oall the prop

al at the thya value whi

? Can I do turn off thyrpplying a coor, GTO.

It can rward forth

annot off by erties

yristor ich is

some ristor, ontrol

10  

(Refer Sl

A small pampere Gturned ofAnode caare the 2 (Refer Sl

What is similar to

lide Time: 2

power GTO GTOs develoff by negatiathode strucsymbols use

lide Time: 23

the structureo SCR, P1 N

1:50)

was developoped by Hitive IG and hcture is the sed to represe

3:00)

e? In what wN1 P2 N2. Th

ped by GE,achi and To

here are the ame, across

ent a GTO.

way it is strhen, in what

general elec

oshiba. It can2 symbolichere are 2 a

ructurally dit way it is d

ctric in 1961n be turned c representatarrows, posi

ifferent fromdifferent? H

and in 1981on by posititions of the itive IG nega

m a thyristorow it is bei

1, a 2.5 kv, 1ive IG and caGTO, the s

ative IG. So,

r? It has 4 ling turned o

1 kilo an be same. these

layers off by

11  

applying thickness The secoI will sho (Refer Sl

See, we hThere is indicatessimilar to So, therethere are and all thcathode. parallel, seen as a Anode issink formand cathois somethadvantagincreasedcathode, cathode a

a negative s of P2 is less

ond differencow you a 3D

lide Time: 24

have P or P1 here, see the doping

o SCR, N2 la

e are large nularge numb

he cathodes So, what yas if there i

a large numb

s same, cathoms the main ode structurehing like thi

ge of doing lid, also the di

this is inteand gate has

IG to the gas in the case

ce is N2 layerD picture and

4:20)

1 N1 P2. Nowhere, again level is ver

ayer is highly

umbers of smber of GTO’sof these GT

you can say is a GTO heer of GTO’s

ode is also scathode andes are highlyis, this is inike a inter distance betwer digitizatio reduced.

ate? We wilof a GTO. W

r is removedd it will be ve

w, N2 is in sa separate N

ry low and thy doped, N1 l

mall islandss. See here, O’s are connis a GTO c

ere or anoths connected i

same, all thed another dify inter digiti

nter digitizatidigitization? ween the gateon, cathode

ll see. See hWhy, I will t

d by itching ery clear, see

small places,N2 layer, a she plus indilayer is very

of cathode P1 N1 P 2 N2

nected to a ccan be seen

her GTO herin parallel. W

e cathodes arfference betwized. What dion, this couThe advanta and a cathoperiphery h

here P1N1 P2

tell you som

in place whee here.

, small islansmall island icates dopingy lightly dop

or in other w2, P1 N1 P 2 Ncommon hean as a large re, another GWhy parallel

re connectedween a GTOdo you meanuld be inter age is that noode is very smhas increase

2 N2, one of me time later.

ere gate con

nds of N2 areof N2 layer

g level is veed.

words, whatN2 see here at sink and t

number of GTO here. Ol?

d to 1 heat sO and a SCR n by highly i

digitizationow the cathomall. If this ed the dista

the differen

ntacts are situ

e found, see r. See, this mery high. So

t I can say isalso P1 N1 Pthat forms af small GTOOne GTO ca

sink and thatis in a GTO

inter digitizen. So, what iode peripheris gate and t

ance between

nce is

uated.

here. minus , it is

s see, P 2 N2

main O’s in an be

t heat O gate ed? It is the ry has this is n the

12  

What is tthe strucdoped, juthough Jand when Now, thelayer pen (Refer Sl

See here with N1 oit is revehad a P snow J1 cais J3.

The reveblock negalso knojunction voltage thturn off poff of a GN minus

the advantagture again. Iunction J2 a3 is also reven is forward

ere is anothenetrates this P

lide Time: 2

in this figuror N minus lerse biased. structure. Noannot block

erse voltage gative voltagwn as a symJ2 and it cahat is becauprocess. NowGTO. See in P.

ge of this intI have a P l

and J3. So, werse biased, biased J2 blo

r structure. SP1 layer and

8:49)

re, this N plulayer. So, in See, when itow, because the negative

blocking cage or a anodmmetrical Gannot block se of J3, anotw, how it spthis, a 3D fi

er digitizatiolayer, it is ewhen it is re

the reverse ocks the volt

See here, vard it is directly

us layer peneother wordst is reverse of this N pl

e voltage, the

apability is vde short strucGTO. Why i

the negativther advantaeeds up the

figure shown

on? I will telequivalent toeverse biaseblocking vo

tage.

riant a N pluy in contact w

etrates at regs there is a dbias, entire us which is e only 1 jun

very small. cture cannotit can block ve voltage. Iage of doing turn off pro

n, here is sam

ll you some o P1 in SCRed, J1 shouldoltage of J3 i

us layer in otwith the N m

gular intervadirect shot be

voltage as win directly i

nction that ca

So in other t block nega

k only positiIf at all, if i this modific

ocess? I will me thing P1 o

time later. N. Junction Jd block the is very smal

ther words, aminus layer o

als and it is detween the awe blocked bin contact wian block the

words, thisative voltageive voltage?it can blockcation is thatell you whi

or P plus hig

Now, you jus1, N layer livoltage bec

ll similar to

a highly dopor the N1 lay

directly in coanode and J1

by J1 becausith anode an negative vo

structure cae. So, this GT It is becau

k is a very at it speeds uile doing the

ghly doped N

st see ightly cause SCR

ped N yer.

ontact when se we nd N1, oltage

annot TO is

use of small

up the e turn

N plus

13  

(Refer Sl

Now, comgate. In Sconductiogate elechappens very nearthe instanduring tu Since thecomparedvery nearhave a ve

lide Time: 3

ming to the SCR, why dion is very sm

ctrode is avain the GTOr to the gatent of turn on

urn on.

e dr by dt id to SCR. Tr to the gateery high dr b

1:24)

inter digitizaid we limit dmall when yailable and aO because ofe. So in othen, a large ar

is very largThis is becaue, large area by dt, I can o

ation, I told dr by dt durinyou turn on tafterwards thf this inter dr words, a la

rea is availab

e, GTO canuse of inter is available

or turn on tim

you, the remng turn on? the device. Ihe conductiodigitization?arge area is ble. So there

n be broughdigitization.

e, so you canme of the GT

mote part of It is becauseIt is a area oon spreads to Even the reavailable du

efore, you ca

ht into condu. Even the rn have a ver

TO reduces.

f a cathode ise the area thof the cathodo the other pemote part ouring the turan have a ve

uction at a remote part ry high dr b

s very near tat is availabde adjacent tparts. Now,of the cathorn on period ery high dr

much fasterof the catho

by dt. So, if

to the le for to the what

ode is d or at

by dt

r rate ode is I can

14  

(Refer Sl

See, in a gates, theconductio (Refer Sl

Now, codifferencthe senselatching conductio

lide Time: 33

3D it looks e cathode, thon very rapi

lide Time: 33

oming to thece between the, in principcurrent. Buton period. W

3:10)

something lhe direction dly that is be

3:43)

e turn on chhe SCR charle, gate signt it is recom

Why? It is b

like this, I hof holes, thecause of a v

haracteristicracteristics anal can be w

mmended thabecause of th

have chosen e direction overy high dr

cs, they are and the GTOwithdrawn onat a positivehis reason, I

a anode shoof electric. Sby dt is pos

similar to O characterist

nce the anode IG is maint

told you on

ort structure. So, GTO canssible.

an SCR. Thtics. It is a lade current itained throu

ne of the lim

So, these arn be brough

here is no matching devis higher tha

ughout durinitations or o

re the ht into

much ce, in

an the ng the one of

15  

the diffecompared Now, asanode cuthe curresmall. Somay get dmaintaincurrent. So, whaton time clooks som (Refer Sl

A high known aafter sompeak valu

rence betwed to a SCR.

sume that amurrent had dient, anode cuo therefore, tdamaged. Soed througho

t is being doncan be reducmething like

lide Time: 36

gate currents the delay t

metime you cue.

een the GTOHolding cur

m doing somipped momeurrent increathere could o therefore, iout. But then

ne is a high ced and after this.

6:18)

t, so anode time. The vocan reduce th

O and SCR rrent of a GT

me disturbanntarily, som

ases very rapbe some hotit is recommn, you do no

pulse of gatr sometime y

current hasoltage acrosshe gate curre

is that holdTO is higher

nce, anode cume of parts ofpidly, the aret spots and b

mended that dot need to m

te current is you can redu

s attained a s the deviceent to IGT. So

ding currentcompared to

urrent has dif the GTO mea that is avabecause of thduring condu

maintain the

provided duuce this gate

study valuee also reduceo, this value

t for a GTOo SCR.

ipped momemight turn oailable for cohis localizeduction periosame magn

uring turn one current. Se

e after someed to its satuis approxim

O is much h

entarily. Sincff and now onduction isd heating, a d, a positive

nitude of the

n, so that theee the wave f

e time td whuration value

mately 10% o

higher

ce the again

s very GTO

e IG is e gate

e turn form,

hat is e. So, of this

16  

(Refer Sl

So, that icase of avoltage dsaturationbring thatransistor Now, devsaturationNow, let flowing o See, thiscurrent isplus alphthem for value. Soplus alph

lide Time: 37

is about the a thyristor wdrops to a ven. Now, youat T2 out of srs, both are i

vice has to bn. How do Ius see what

out of the ga

expression s given by a

ha2. Whereinthe SCR. W

o, in on stateha2.

7:09)

turn on of twhen the thyery low valuu want to tursaturation. Sin saturation

be turned ofI bring this t is the relat

ate terminal.

that we havalpha2 into IG

n, alpha1 and When SCR ie, I can negl

the GTO. Noyristor is onue, could bern off the GTSee in this fin.

ff. How do Itransistor o

tionship betw

ve derived fG plus ICBO ialpha2 are c

is in on stateect this term

ow, coming n, both T1 ane of the ordeTO, so first

figure, this is

I turn it off?ut of saturaween the ano

for the SCRis a sum of ommon basee, we have r

m, IA can be

to the turn nd T2 are iner of 1.5 vol

thing that hs T1, PNP tra

? You have tation? I haveode current

R is still valICO1 and ICO

e current gaireduced the given by ICB

off of a GTOn saturation. lts or so. Sohas to be donansistors an

to bring thise to reduce and the gate

lid here. TheO2 divided bins. We havgate curren

BO divided b

O, so even iThat is wh

o, T1 and T2 ane is you had this is T2,

s transistor othe base cue current tha

e total satury 1 minus a

ve already dent to a very by 1 minus a

in the hy the are in ave to NPN

out of urrent. at has

ration alpha1

efined small

alpha1

17  

(Refer Sl

See here,when theequal to divided band the gminus 1. How do Ishould befor this trthe thickbetween comparedalpha2.

Now, howIG is flowgate term

lide Time: 39

, this is the ce numeratorminus of al

by alpha2. Sogate, it come

I improve the as high as ransistor, thi

kness of P2 la SCR and

d to a SCR a

w to turn offwing out of tminal, so hole

9:50)

current that r becomes 0lpha2 into IG

o, if I want toes like this,

his gain? In opossible. W

is is N1 P2 Nlayer less. P

d a GTO, I tand second

f a GTO? Wthe gate, IG ies are extrac

has to be tur. So, when

G, see here. o find out thIA divided b

other words,What is alpha2

N2. How do I P2 layer shoutold you theis increase i

What happensis connectedcted from P2.

rned off. Seecan you maSo, the rela

he gain or thby IG is equa

how do I m2? It is a gaimake alpha2

uld be very e first differin doping lev

s exactly durd to P2. See h

e, in the prevake this num

ationship is Ihe relationshal to alpha2 d

make this gainin of N1 P2 N2 as high as pthin. See, t

rence that I vel in N2, the

ring the turn here, IG is P2

vious equatimerator zeroIG is equal

hip between tdivided by a

n as high as N2 transistorpossible? Onthat is one told you, la

ereby increa

off process?2, now IG is f

ion, IA becomo? When, IC

to minus ofthe anode cualpha1 plus a

possible? A. See here, ane way is to of the differayer of P2 isasing the val

? IG has reveflowing out o

mes 0 CBO is f ICBO urrent alpha2

Alpha2 alpha2

make rence s less lue of

ersed, of the

18  

(Refer Sl

So, as thholes or his appliejunction the holesreverse bConductiaway fro Now, it mthere wouthat show

lide Time: 42

ese extractioholes from td in P2 baseand both gos extraction biased but tion area dropm the gate.

may so happuld be a loc

wing the turn

2:50)

ons take plache anode aree region andoes into cut o

continues, then IG is sps. Now, the

pen that the alize heating

n off process

ce, the voltae extracted fd eventuallyoff. But thenP2 is furthe

still flowing e current ma

current deng and devices, it is someth

age drop is dfrom the P ba

this voltagen, entire turnr depleted. out. So, P

ay be flowin

nsity in thosee may fail. Shing like thi

developed inase. So, durie, reverse bn off processSee, first is2 gets furthe

ng in the rem

e parts may So, this has ts.

n the P2 regioing this proc

biases your gs is not coms gate cathoer depleted.

mote parts of

increase anto be avoide

on. I will telcess, voltagegate and cat

mpleted as yeode junction. What happf the anode o

nd if this hapd. See, the f

ll you e drop thode et. As n gets pens? or far

ppens figure

19  

(Refer Sl

All the hto flow tthat is aveventuall (Refer Sl

Now, thegain of agenerally

lide Time: 45

holes are divthrough the vailable, it mly device ma

lide Time: 45

e turn off of a GTO is vey.

5:02)

erted towardarea which

may form oray fail.

5:39)

f a GTO is gery low. Tur

ds the gate. Tis far away

r in that area

greatly influern off gain

The P2 gets ffrom the ga

a, the curren

enced by theis very low

further depleate area. Thent density m

e turn off cirw, could be o

eted, now anere is a redu

may increase

rcuit. Unforof the order

node currentuction in the

localize hea

rtunately, turr of say, 6 t

t tries e area ating,

rn off to 15,

20  

So therefvoltage dSo, gate short durcurrent re (Refer Sl

At steadySomewhstill remaanode cu Now, whThere hahigh. So,in series very smaRC circu Now, theknown awanted toonwards, Now, beccurrent, aof this thof the cir

fore, if anoddevice. So, icurrent that ration. So, aemains cons

lide Time: 47

y state, gateere at this poains constan

urrent remain

hat happens as to be a snu, you can usewith thyrist

all inductor. uit looks like

ere is a diods loop induco turn off th, anode curre

cause of thisanode curren

here is goingrcuit.

de current isif anode curris flowing o

as the gate ctant. So, this

7:10)

e current hasoint, it desirent for ts durns approxima

after ts? Thubber circuite a very smaor to limit dSo, the ratin this, someth

de, it has itsctance, in doe thyristor, sent falls at a

s loop inducnt cannot sta to be a volt

s 100 amperrent is arounout of the tecurrent startss period is kn

s been, we he to turn off ation. So, thately constan

his process ht to turn off

all inductor indi by dt durinng of di by dhing like this

s own turn ootted lines. so IG has revvery fast rat

ctance and barts flowing ttage spike be

res, by the wnd 100 ampeerminal is 10s flowing ounown as the

have to reduf the GTO. Shis is knownnt and this p

has to be stuf a GTO. I ton series withng turn off.dt, even nows.

on time andThere is a v

versed, for sote.

because of ththrough the ecause of the

way GTO iseres, gain is0 amperes anut of the ter storage time

uce the gate So, IG reversen as storage

period ts can

udied by takold you, di bh a GTO. WSimilarly, to

w … there ha

d I have shovery small iome time IA

his diode, tusnubber circe inductance

s a high curr of the ordend it is forturminal, for se. See in this

current to aes, though IG

e time. Durilast for a few

king a snubbby dt rating oe have conno limit di byas to be a tu

own a small inductor in dremains con

urn on time ocuit immediae which is th

rent device,er of say, 6 tunately for asome time as figure.

a very low vG has reverseing storage w microseco

ber into accof a GTO is

nected an indy dt, we requurn off snubb

inductor whdotted lines.nstant and fr

of the diodeately and bechere in other

high to 15. a very anode

value. ed, IA time,

onds.

count. s very ductor uire a ber, a

hat is You

rom ts

e, this cause parts

21  

If this infinds a pthereforedangerou So therefthat I havcritical inis knownas the tai Now, theNow, whzero and free charis nothinrequire a See, the increasesincreasesof the GTSee, voltcurrent, vplace devturn off lthe tail cu (Refer Sl

ductance 0 aath, the capa

e because ofus, in the sen

fore, the snuve shown in n the case ofn as the fall til current, sta

e voltage achat is this taithe gate cur

rges, they exng but the b finite time t

problem hes. As the thics. So in otherTO. So, whtage across voltage is a vice are highlosses? So, ourrent durati

lide Time: 54

and turn on acitor. Now,f this a larg

nse that devic

ubber circuitthe dotted li

f GTO. So, ttime and thiarts flowing

ross the GTil current? Trrent is samexist in N1 layblocking layto recombine

re is as the ckness of Nr words, the

hat is the conthe device reasonably hh. So, turn oone way to reion? This dt

4:47)

time is very because of ge di by dtce may fail b

t layout is vine should bthe anode cuis is very smthrough this

TO is limitedThis tail curre as the anodyer. The curryer, lightly de.

voltage rati1 layer incretail current

nsequence ofstarted incrhigh value itff losses in aeduce is to rhas to be red

y small, thenthis inductot, this spikebecause of th

very importabe as small aurrent has fa

mall and froms snubber cir

d by the dv ent, that per

de current. Sorent due to thdoped layer.

ing increaseases, time taperiod incref having a heasing, currt has attainea GTO, theyreduce the faduced.

n may be, imor and diode,e appears achis spike.

ant. The loopas possible. Sallen to a verm there onwarcuit.

by dt, it is riod Ik is equo, this tail cuhe free charg. These carr

s N1 layer, taken for theeases with thhigher fall timrent in the ded, so therefoy are significall or tail cur

mmediately th, this currentcross the G

p inductanceSnubber circry low valueards a curren

determined ual to zero, current is corrges which exriers are num

the thicknesse carriers t

he blocking vme or sorry, device is stiore, the losscant. So, howrrent duration

his anode cut gets choked

GTO. It coul

e, the induccuit layout ise. So, the endnt what is kn

by the dv bcathode currresponding txists in N1 wmerous and

ss of the N1

o recombinevoltage capa

higher tail till finite, thes that are taw do I reducn. How to re

urrent d and ld be

ctance s very d of tf nown

by dt. ent is to the which d they

layer e also ability time? e tail aking ce the educe

22  

Having dcurrent dsaid one it does is (Refer Sl

Those andoped. Wrecombin So this hquickly. reduces bNegative Thank yo

decided on tdepends on thof the advan, see this.

lide Time: 55

node shortinWhat they done more quic

highly dopedSo thereforebut then dev

e voltage it c

ou.

the voltage rhe thicknessntages of ano

5:14)

ng N layers ao is this heavckly.

d N cells, the, your fall ovices no lonannot block

rating, N1 la of N1. Is theode shorting

are highly dvily doped N

hey helped tor sorry, tailnger symme. So, with th

ayer, thickneere a way ou is to reduce

doped. They

N cells, they m

he minority l current timtrical. Now,

his I will con

ess of N1 layut? Yes. Whye the turn off

y were all wmake the mi

carriers trame reduces. S

, it can blocnclude my to

yer gets decy did we do f time. How

where N plusinority carrie

apped in N1, Sorry, it is ack only the day’s lecture

cided and thanode shortidoes it do?

s, they are hers trapped i

recombine a tail current

positive vole.

he tail ing? I What

highly in N1,

more t time ltage.