IGBT驱动电路分析.ppt

IGBTGateDriverCalculation,GateDriverRequirement,WhatisthemostimportantrequirementforanIGBTdriver?,GatePeakcurrent,Conditionsforasafetyoperation,WhichgatedriverissuitableforthemoduleSKM200GB128D?,Designparameters:fsw=10kHzRg=?,reverserecoverycurrentDiodeshouldbe-1.5xIdiodeby80degreecase130Ax1.5=195A,Gateresistorinrangeof“testgateresistor”,Howtofindtherightgateresistor?,Rg=7Ohm,TwogateresistorsarepossibleforturnonandturnoffRon=7OhmRoff=10Ohm,195Amaxreverserecoverycurrent,DifferencebetweenTrench-andSPTTechnology,TrenchTechnologyneedsasmallerGatechargeDriverhastoprovideasmallerGatechargeSPTTechnologyneedsmoreGatechargecomparedtoTrenchTechnologyDriverhastoprovideahigherGatecharge,DriverperformancedifferentIGBTtechnologiesneedsdifferentgatecharge,TrenchIGBTwithsamechipcurrent,Gatechargeis2.3uC,DriverperformancedifferentIGBTtechnologiesneedsdifferentgatecharge,SPTIGBTwithsamechipcurrent,Gatechargeis3uC,Demandsforthegatedriver,ThesuitablegatedrivermustprovidetherequiredGatecharge(QG)powersupplyofthedrivermustprovidetheaveragepowerAveragecurrent(IoutAV)powersupplyGatepulsecurrent(Ig.pulse)mostimportantattheappliedswitchingfrequency(fsw),-8,15,1390,DeterminationofGateCharge,Gatecharge(QG)canbedeterminedfromfig.6oftheSEMITRANSdatasheet,QG=1390nC,Thetypicalturn-onandturn-offvoltageofthegatedriverisVGG+=+15VVGG-=-8V,Calculationoftheaveragecurrent,Calculationofaveragecurrent:IoutAV=P/UV=+Vg+-VgwithP=E*fsw=QG*V*fswIoutAV=QG*fsw=1390nC*10kHz=13.9mA,Absolutevalue,Powersupplyrequirements,GatechargeThepowersupplyorthetransformermustprovidetheenergy(Semikronisusingpulsetransformerforthepowersupply,wemustconsiderthetransformedaveragepowerfromthetransformer)AveragecurrentIsrelatedtothetransformer,Calculationofthepeakgatecurrent,ExaminationofthepeakgatecurrentwithminimumgateresistanceE.g.RG.on=RG.off=7Ig.pulsV/RG+Rint=23V/7+1=2.9A,Pulsepowerratingofthegateresistor,PtotalGateresistorPpulseGateresistor=IoutAVxVMoreinformation:,Theproblemoccurswhentheuserforgetsaboutthepeakpowerratingofthegateresistor.ThepeakpowerratingofmanyordinarySMDresistorsisquitesmall.ThereareSMDresistorsavailablewithhigherpeakpowerratings.Forexample,ifyoutakeanSKDdriverapart,youwillseethatthegateresistorsareinadifferentSMDpackagetoalltheotherresistors(exceptoneortwootherplacesthatalsoneedhighpeakpower).Theproblemwaslessobviouswiththroughholecomponentssimplybecausetheresistorswerephysicallybigger.ThePhilipsresistordatabookhasagoodsectiononpeakpowerratings.,Choiceofthesuitablegatedriver,TheabsolutemaximumratingsofthesuitablegatedrivermustbeequalorhigherthantheappliedandcalculatedvaluesGatechargeQG=1390nCAveragecurrentIoutAV=13,9mAPeakgatecurrentIg.pulse=2.9ASwitchingfrequencyfsw=10kHzCollectorEmittervoltageVCE=1200VNumberofdriverchannels:2(GBmodule)dualdriver,Comparisonwiththeparametersinthedriverdatasheet,Calculatedandappliedvalues:Ig.pulse=2.9ARg=7+RintIoutAV=13.9mAfsw=10kHzVCE=1200VQG=1390nC,Accordingtotheappliedandcalculatedvalues,thedrivere.g.SKHI22AisabletodriveSKM200GB128D,PCBDriverandPCBmountableDriverforsingle,halfbridge,sixpackmodulesintegratedpotential-freepowersupplyswitchingfrequencyupto100kHzoutputpeakcurrentupto30AGatechargeupto30Cdv/dtcapabilityupto75kV/shighEMIimmunityTTL-anCMOS-compatibleinputsandoutputswithpotentialisolationviaoptocouplerortransformer(isolationupto4kVAC)protection(interlock,shortpulsesuppression,shortcircuitprotectionviaVCE-monitoring,undervoltagemonitoring,errormemoryanderrorfeedback),SEMIDRIVER,Productoverview(importantparameters),DrivercoreforIGBTmodules,SimpleAdaptableExpandableShorttimetomarketTwoversionsSKYPER(standardversion)SKYPERPRO(premiumversion),AssemblyonSEMiXTM3ModularIPM,SKYPERDriverboardSEMIX3IGBThalfbridgewithspringcontacts,SKYPERmorethanasolution,modularIPMusingSEMiX,withadapterboard,solderdirectlyinyourmainboard,take3for6-packs,SelectionoftherightIGBTdriver,Advice,Problem1-Crossconduction,Lowimpedance,Crossconductionbehavior,vCE,T1(t)iC,T1(t),VCC,IO,0,t,vGE,T1(t)vGE,T2(t),VGE,Io,VGE(th),0,t,VGG+,VCC,IO,0,t,vCE,T2(t)=vF,D2(t)iF,D2(t),iC,T2(t),T1,D1,T2,D2,iv,T2,WhychangesVGE,T2whenT1switcheson?,IGBT-Parasiticcapacitances,WhentheoutervoltagepotentialVchanges,theloadQhastofollowThisleadstoadisplacementcurrentiV,Switching:DetailedforT2,iv,T2,vCE,T2,vGE,T2,iC,T2,RGE,T2,CGC,T2,DiodeD2switchesoffandtakesoverthevoltageT2“sees”thevoltageoverD2asvCE,T2,Withthechangedvoltagepotential,theinternalcapacitanceschangetheirchargeThedisplacementcurrentiv,T2flowsviaCGC,T2,RGE,T2andthedriver,iv,T2causesavoltagedropinRGE,T2whichisaddedtoVGE,T2,IfvGE,T2VGE(th)thenT2turnson(ThereforeSKrecommends:VGG-=-5-8-15V),Problem2-gateprotection,Z16-18,Gateclamping-how?,Z18,PCBdesignbecausenocableclosetotheIGBT,Problem3-boosterforthegatecurrent,UseMOSFETforthebooster,ForsmallIGBTsisok,Problem4-Shortcircuit,Overvoltage1200V-ischiplevel-considerinternalstrayinductance+/-20V-gateemittervoltage-considerswitchingbehavioroffreewheelingdiodeOvercurrentPowerdissipationofIGBT(shortcircuitcurrentxtime)Chiptemperaturelevel,Problem5deadtimebetweentopandbottomIGBT,Turnonandturnoffdelaymustbesymetrical,Deadtimeexplanation,Deadtimeexplanation,Example:Deadtime=3uslogiclevelTurnondelay1usTurnoffdelay2.5usTdtoffdelay+tondelay=realdeadtimeRealdeadtime:3us(2.5us+1us)=1.5us,Ourfinalrecommendation,IGBTdrivermustprovidethepeakGatecurrentThestrayinductanceshouldbeverysmallinthegatedrivercircuitGate/E