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首页 电力电子技术第四版课后题答案第一章(Power electronics technology f…

电力电子技术第四版课后题答案第一章(Power electronics technology fourth edition, after-school questions, answers Chapter 1).doc

电力电子技术第四版课后题答案第一章(Power electro…

璐璐公馆i
2018-04-26 0人阅读 举报 0 0 0 暂无简介

简介:本文档为《电力电子技术第四版课后题答案第一章(Power electronics technology fourth edition, after-school questions, answers Chapter 1)doc》,可适用于社会民生领域

电力电子技术第四版课后题答案第一章(Powerelectronicstechnologyfourthedition,afterschoolquestions,answersChapter)电力电子技术第四版课后题答案第一章(Powerelectronicstechnologyfourthedition,afterschoolquestions,answersChapter)Thefirstchapter,powerelectronicdevicewhataretheconditionsforthyristorswitchingonAnswer:theconditionthatthethyristorisswitchedonisthatthethyristorreceivesthepositiveanodevoltageandappliesatriggercurrent(pulse)atthegateOr:uAK>anduGK>whataretheconditionsformaintainingthethyristorconductionHowtomakethechangeforthethyristorturnoffAnswer:theconditionofmaintainingthethyristorconductionistomakethethyristorcurrentgreaterthantheminimumcurrenttomaintainthethyristorcurrent,thatis,tomaintaincurrentTomakethethyristorconductionbychangeoffcurrent,appliedvoltageandtheexternalcircuitcanbeusedtomaketherolethroughthethyristorisreducedtoavalueclosetozero,thatistomaintainthecurrent,canmakethethyristorturnonswitchofftheshadowpartinFigisthecurrentwaveformofthethyristorinthepasssectionThemaximumcurrentvalueofeachwaveformisImThecurrentaveragevalueofeachwaveformiscalculatedbyId,Id,IdandcurrenteffectivevaluesI,IandIFigthyristorconductionwaveformSolution:a)Id==()ImI==ImB)Id==()ImI==IC)=Id==ImI==ImOnthequestionifyoudonotconsiderthesafetymargin,askAthyristor,IdIdId,theaveragecurrentcanbesentforAtthistime,correspondingtothecurrentmaximumvalueofIm,Im,ImeachSolution:ratedcurrentIT(AV)=Athyristor,allowingcurrenteffectivevalueI=A,calculatedbytheresultsoftheabovetitleA)Im,Id,ImB)Im,Id,ImC)Im=,I=,Id=,Im=GTOandcommonthyristorsarePNPNstructuresWhydoesGTOturnoffitself,andordinarythyristorsdonotAnswer:GTOandordinarythyristorwithPNPNstructurebyPNPandNPNconstitutetwotransistorsV,V,respectively,withthecommonbasecurrentgainandanalysisbytheordinarythyristordeviceisavailable,=criticalconductionconditions>>,twoequivalenttransistorsaresupersaturatedandconnectedcannotmaintainsaturationconductionandturnoffGTOisabletoturnoffitself,andtheordinarythyristorcannot,becausetheGTOandthecommonthyristoraredifferentintermsofdesignandprocess:)GTOislargerindesign,sothetransistorVissensitivetocontrolandeasytoturnoffbyGTO)GTOiscloserto,commonthyristor,whileGTOis,GTOsaturationisnotdeep,nearcriticalsaturation,whichprovidesfavorableconditionsforgatecontrolshutdown)themultielementintegratedstructuremakesthecathodeareaofeachGTOelementverysmall,andthedistancebetweenthegateandcathodeisgreatlyshortened,sothatthesocalledtransverseresistanceinthePpolarregionisverysmall,sothatitispossibletodrawoutalargercurrentfromthegatehowtopreventdamageduetoelectrostaticinductionofpowerMOSFETAnswer:thegateinsulationofthepowerMOSFETisveryweakandisvulnerabletobreakdownTheinputcapacitorofMOSFETisalowleakagecapacitorWhenthegateisopen,itisvulnerabletostaticinterferenceandchargemorethanofthebreakdownvoltageTherefore,inordertopreventdamageduetoelectrostaticinduction,MOSFETshouldpayattentiontothefollowingpoints:Generally,thethreeelectrodesareshortedwhennotinuseWhenassembling,thehumanbody,theworktableandtheelectricironmustbegrounded,andalltheinstrumenthousingsmustbegroundedwhentestedInthecircuit,thezenerdiodeisoftenconnectedbetweenthegateandthesourcetopreventthevoltagefrombeingtoohighLeakageandsourcemustadoptbuffercircuitandothermeasurestoabsorbovervoltageWhatarethefeaturesoftheIGBT,GTR,GTOandpowerMOSFETdrivecircuitsA:IGBTdrivecircuitischaracterizedby:drivecircuithasasmalloutputresistance,IGBTisvoltagedrivendevice,IGBTdriveusingadedicatedhybridintegrateddriverTheGTRdrivecircuitischaracterizedinthatthedrivingcurrentdrivingcircuitisprovidedwithadvancedenoughsteep,andtherehavebeensomeimpact,whichcanacceleratetheopeningprocess,reducepowerloss,turnoff,thedrivingcircuitcanprovideamplitudelargeenoughtoreversethebasedrivecurrentandreversebiascutoffvoltage,tospeedoffoffspeedTheGTOdrivecircuitischaracterizedinthattheGTOrequirementsofthedrivecircuitprovidesthedrivingcurrentforwardenoughamplitudeandsteepness,andgenerallyrequireinthewholeconductionperiodofappliedcurrentFrontGateoff,anegativegatecurrentamplitudeandsteepnessismoredemanding,usuallyincludingtheopeningofthedrivecircuitanddrivecircuit,closedoffthedrivecircuitandthegatebiascircuitthreePowerMOSFETdrivecircuitfeatures:therequirementsofthedrivecircuithasasmallinputresistance,drivingpowerissmall,andthecircuitissimplewhatisthemainfunctionofthesnubbercircuitofthefullycontrolleddeviceThefunctionofeachcomponentinRCDsnubbercircuitisanalyzedAnswer:themainfunctionofthefullycontrolleddevicesnubbercircuitistosuppresstheInternalOvervoltageofthedevice,dudtorovercurrentanddidt,andreducetheswitchinglossofthedeviceRCDbuffercircuit,theroleofeachcomponentis:whentheopening,CsdischargethroughtheRs,Rsplayaroleinlimitingthedischargecurrentturnoff,theloadcurrentthroughtheVDsshuntfromtheCs,reducingthedudt,inhibitovervoltagetrytoexplaintheadvantagesanddisadvantagesofIGBT,GTR,GTOandpowerMOSFETrespectivelySolution:theadvantagesanddisadvantagesofIGBT,GTR,GTOandpowerMOSFETarecomparedasfollows:DeviceadvantagesanddisadvantagesIGBThighswitchingspeed,lowswitchingloss,highcapacitysurgecurrent,lowvoltagedrop,highinputimpedance,voltagedrive,smalldrivingpowerswitchspeedislowerthanMOSFETpower,voltage,currentcapacityislessthanGTOGTRhashighvoltage,largecurrent,goodswitchingcharacteristics,highflowcapacity,lowsaturationvoltage,lowswitchingspeed,currentdrive,largedrivingpower,complexdrivingcircuit,andtwobreakdownproblemsGTOvoltage,largecurrentcapacity,suitableforhighpowerapplications,withtheconductivitymodulationeffect,theflowcapacityofstrongcurrentgainisverysmall,turnoffthegatenegativepulsecurrent,lowswitchingspeed,largedrivingpower,thedrivingcircuitiscomplex,lowswitchingfrequencyElectricpowerTheMOSFETswitchhastheadvantagesofhighspeed,highinputimpedance,goodthermalstability,smalldrivingpowerandsimpledrivingcircuit,Highoperatingfrequency,notwobreakdownproblems,lowcurrentcapacityandlowvoltageresistancearegenerallyapplicabletopowerelectronicdeviceswithpowernotexceedingkW

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