IGBTBi:

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Gii thiu

Transistor c cc iu khin cch ly(Insulated Gate Bipolar Transistor),hay IGBT lmt linh kin bn dn cng sut 3 cc c pht minh bi Hans W. Beck v Carl F.Wheatley vo nm 1982.IGBT kt hp kh nng ng ct nhanh ca MOSFET v khnng chu ti ln ca transistor thng. Mt khc IGBT cng l phn t iu khin bngin p, do cng sut iu khin yu cu s cc nh.

Cu to, nguyn l hot ng

V cu trc bn dn, IGBT rt ging vi MOSFET, im khc nhau l c thm lpni vi collector to nn cu trc bn dn p-n-p gia emiter( tng t cc gc) vicollector(tng t vi cc mng), m khng phi l n-n nh MOSFET . V th c thcoi IGBT tng ng vi mt transistor p-n-p vi dng base c iu khin bi mtMOSFET.

Di tc dng ca p iu khin Uge>0, knh dn vi cc ht mang in l cc in tc hnh thnh, ging nh cu trc MOSFET.Cc in t di chuyn v pha collectorvt qua lp tip gip n-p nh cu trc gia base v collector transistor thng, tonn dng collector.

k hiu igbt

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cu trc bn dn

c tnh ng ct ca IGBT

Do cu trc n-p-n m in p thun gia C v E trong ch dn dng IGBT thphn hn so vi Mosfet. Tuy nhin do cu trc ny lm cho thi gian ng ct ca IGBTchm hn so vi Mosfet, c bit l khi kha li. Trn hnh v th hin cu trc tngng ca IGBT vi Mosfet v mt Tranzitor p-n-p. K hiu dng qua IGBT gm haithnh phn: i1 dng qua Mosfet, i2 dng qua Tranzitor. Phn Mosfet trong IGBT cs thkha li nhanh chng nu x ht c in tch gia G v E, do dng i1= 0, tuy hini2 s khng suy gim nhanh chng c do lng in tch ly trong (tng ngvibazo ca cu trc p-n-p) ch c th mt i do qu trnh t trung ha in tch. iu nyxut hin vng dng in ko di khi kha IGBT.

Vng lm vic an ton (Safe Operating Area)

Vng lm vic an ton c th hin di dng th quan h gia in p v gi trdng in ln nht m phn t c th hot ng c trong mi ch , khi dn, khikha, cng nh trong cc qu trnh ng ct.

Khi in p t ln cc iu khin v emitor l dng v hnh th hai th in p ny lm. Khi in p iu khin dng, SOA c dng hnh ch nht vi gc hn ch phatrn, bn phi, tng ng vi ch dng in v in p ln. iu ny c ngha l khichu k ng ct cng ngn, ng vi tn s lm vic cng cao th kh nng ng ct cngsut cng suy gim. Khi t in p iu khin m ln cc iu khin v emitor, SOAli b gii hn vng cng sut ln do tc tng in p qu ln s dn n xut hindng in ln a vo vng p ca cc iu khin, tc dng ging nh dng iu khinlm IGBT m tr li nh tc dng i vi cu trc ca thyristor. Tuy nhin kh nngchu ng tc tng p IGBT ln hn nhiu so vi cc phn t bn dn cng sutkhc .

Gi tr ln nht ca dng cho php collector cho php Icm c chn sao cho trnh chin tng cht gi dng, khng kha li c, ging nh thyristor. Hn na, inp iu khin ln nht Uge cng phi c chn c th gii hn c dng in Icetrong gii hn ln nht cho php ny trong iu kin s c ngn mch bng cch chuyni bt buc t ch bo ha sang ch tuyn tnh. Khi dng Ice c gii hn

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khng i, khng ph thuc vo in p Uce lc . Tip theo IGBT phi c kha litrong iu kin , cng nhanh cng tt trnh pht nhit qu mnh . Trnh c hintng cht gi dng bng cch lin tc theo di dng collector l iu cn thit khi thitk IGBT.

Vn bo v IGBT

Thng thng IGBT c s dng trong nhng mch ng ct tn s cao, t 2 n hngchc kHz. tn s ng ct cao nh vy, nhng s c c th ph hy phn t rt nhanhv dn n ph hng ton b thit b. S c thng xy ra nht l qu dng do ngnmch t pha ti hoc t cc phn t c li do ch to hoc lp rp.

C th ngt dng IGBT bng cch a in p iu khin v gi tr m. Tuy nhin quti dng in c th a IGBT ra khi ch bo ha dn n cng sut pht nhit tngt ngt, ph hy phn t sau vi chu k ng ct. Mt khc khi kha IGBT li trongmt thi gian rt ngn khi dng in rt ln dn n tc tng dng qu ln, gy qup trn collector, emiter, lp tc nh thng phn t. Trong s c qu dng, khng thtip tc iu khin IGBT bng nhng xung ngn theo qui lut nh c, cng khng ngin l ngt xung iu khin dp tt dng in c.

C th ngn chn hu qu ca vic tt dng t ngt bng cch s dng cc mch dpRC (snubber circuit), mc song song vi cc phn t. Tuy nhin cc mch dp c thlm tng kch thc v gim tin cy ca thit b. Gii php ti u c a ra l lmchm li qu trnh kha ca IGBT, hay cn gi l kha mm (soft turn-off) khi pht hinc s c dng tng qu mc cho php.

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IGBTGii thiuCu to, nguyn l hot ngc tnh ng ct ca IGBTVng lm vic an ton (Safe Operating Area)Vn bo v IGBT