Въведение
GTO (Gate-Turn-OffThyristor) е съкращението на Gate-Turn-OffThyristor, което е производно на тиристор. Въпреки това, той може да бъде изключен чрез прилагане на отрицателен импулсен ток през затвора, което е напълно контролирано устройство.
Структурата на GTO
GTO,likeordinarythyristors,isaPNPNfour-layersemiconductorstructure,andtheanodeisalsodrawnfromtheoutside.Cathodeandgate.Butunlikeordinarythyristors,GTOisamulti-elementpowerintegrateddevice.Althoughthreepolesarealsodrawnfromtheoutside,itcontainsdozensorevenhundredsofsmallGTOunitswithacommonanode.ThecathodesandgatesoftheseGTOunitsareconnectedinparallelinsidethedevice.Itisdesignedtoachievegatecontrolshut-off..
GTOinternalstructurediagramandelectricalgraphicsymbolsGTOworkingprinciple:
Fromthefigure,wecanseethecompositionofPNPandNPNThetwothyristorsV1andV2havecommonbasecurrentgainsa1anda2respectively.
1. Когато 1+a2=1, това е критичното състояние на включване на устройството.
2.Whena1+a2>1,itistheconditionthatthetwotransistorsareoversaturatedandturnedon.
3.Whena1+a2<1,itistheconditionthatthesaturatedconductioncannotbemaintainedandtheshut-offconditionisnotmaintained.
Разликата между GTO и обикновен тиристор
1.Makea2largerwhendesigningthedevice,sothatthetransistorV2canbecontrolledsensitively,sothatGTOcanbeeasilyturnedoff.
2.Makea1+a2tendtobe1.Ordinarythyristora1+a2>=1.15,andGTOisapproximately1.05,sothatthesaturationofGTOisnotdeepwhenitisturnedon,anditisclosertocriticalsaturation,whichisThegatecanbeturnedoffcontrolprovidesapowerfulcondition.Theunfavorablefactor,theconductionistheincreaseinthepressuredropofthepipe.
3.TheareaofthecathodeofeachGTOunitintheintegratedstructureissmall,andthedistancebetweenthegateandthecathodeisgreatlyshortened,whichmakesthelateralresistanceoftheP2baseregionsmall,andthegatedrawsalargercurrentbecomepossible.
4.Има по-бърз процес на включване от обикновените тиристори и може да издържи на повече напрежение.
Основните параметри на GTO
1.Максималният аноденток на изключванеIATO.
2.Текущо усилване при изключванеβИзкл.=IATO/IGM.
IGMisthemaximumvalueofnegativegatepulsecurrent.βOffisgenerallyonlyabout5.ThisisthemaindisadvantageofGTO.
3.Turn-ontimeTonTurn-ontimereferstothesumofthedelaytimeandtherisetime.ThedelaytimeofGTOisgenerally1~2us,andtherisetimeincreaseswiththeincreaseofthehomomorphicanodecurrentvalue.
4.Turn-offtimeToffTurn-offtimereferstothesumofstoragetimeandfalltime,excludingtailtime.ThestoragetimeofGTOincreaseswiththeincreaseofanodecurrentvalue,andthefalltimeisgenerallylessthan2us.
Тиристор за изключване с помощта на порта
Thegate-assistedturn-offthyristorwillonlyaddnegativevoltagetothegateatacertainmomentaftertheanodecurrentcrossesandreverses,sothatthedeviceresumesblockingGTO.Thegate-assistedturn-offthyristorusuallyadoptsanenlargedgateandcathodeshort-circuitstructure,andthegateandcathodepatternsadoptahighlyinterdigitatedstructure.Theadvantagesofthisdeviceareshortturn-offtime,goodturn-oncharacteristics,andhigherallowableon-statecurrentriserateandon-statevoltageriserate.Itcanbeusedtoformcircuitswithhigheroperatingfrequenciessuchaschoppersandinverters.