IGBT驱动电路分析课件

IGBTGateDriverCalculationGateDriverRequirementWhatisthemostimportantrequirement

foran

IGBTdriver?GatePeakcurrentConditionsforasafetyoperationWhichgatedriverissuitableforthemoduleSKM200GB128D?Designparameters:fsw=10kHzRg=?reverserecoverycurrentDiodeshouldbe-1.5xIdiodeby80degreecase

130Ax1.5=195AGateresistorinrangeof“test–gateresistor”Howtofindtherightgateresistor?Rg=7OhmTwogateresistorsarepossibleforturnonandturnoffRon=7OhmRoff=10Ohm195A–maxreverserecoverycurrentDifferencebetweenTrench-andSPTTechnologyTrenchTechnologyneedsasmallerGatechargeDriverhastoprovideasmallerGatechargeSPTTechnologyneedsmoreGatechargecomparedtoTrenchTechnologyDriverhastoprovideahigherGatechargeDriverperformance–differentIGBTtechnologiesneedsdifferentgatechargeTrenchIGBTwithsamechipcurrentGatechargeis2.3uCDriverperformance–differentIGBTtechnologiesneedsdifferentgatechargeSPTIGBTwithsamechipcurrentGatechargeis3uCDemandsforthegatedriverThesuitablegatedrivermustprovidetherequiredGatecharge(QG)–powersupplyofthedrivermustprovidetheaveragepowerAveragecurrent(IoutAV)–powersupplyGatepulsecurrent(Ig.pulse)–mostimportantattheappliedswitchingfrequency(fsw)-8151390DeterminationofGateCharge

Gatecharge(QG)canbedeterminedfromfig.6oftheSEMITRANSdatasheetQG=1390nCThetypicalturn-onandturn-offvoltageofthegatedriverisVGG+=+15VVGG-=-8VCalculationoftheaveragecurrentCalculationofaveragecurrent:IoutAV=P/UV=+Vg+[-Vg]withP=E*fsw

=QG*V*fsw

IoutAV=QG*fsw

=1390nC*10kHz=13.9mAAbsolutevaluePowersupplyrequirementsGatechargeThepowersupplyorthetransformermustprovidetheenergy(Semikronisusingpulsetransformerforthepowersupply,wemustconsiderthetransformedaveragepowerfromthetransformer)AveragecurrentIsrelatedtothetransformerCalculationofthepeakgatecurrentExaminationofthepeakgatecurrentwithminimumgateresistanceE.g.RG.on=RG.off=7Ig.puls

≈V/RG+Rint

=23V/7+1=2.9APulsepowerratingofthegateresistorPtotal–GateresistorPpulseGateresistor=IoutAVxV

Moreinformation:Theproblemoccurswhentheuserforgetsaboutthepeakpowerratingofthegateresistor.Thepeakpowerratingofmany"ordinary"SMDresistorsisquitesmall.ThereareSMDresistorsavailablewithhigherpeakpowerratings.Forexample,ifyoutakeanSKDdriverapart,youwillseethatthegateresistorsareinadifferentSMDpackagetoalltheotherresistors(exceptoneortwootherplacesthatalsoneedhighpeakpower).Theproblemwaslessobviouswiththroughholecomponentssimplybecausetheresistorswerephysicallybigger.ThePhilipsresistordatabookhasagoodsectiononpeakpowerratings.ChoiceofthesuitablegatedriverTheabsolutemaximumratingsofthesuitablegatedrivermustbeequalorhigherthantheappliedandcalculatedvaluesGatechargeQG=1390nCAveragecurrentIoutAV=13,9mAPeakgatecurrentIg.pulse=2.9ASwitchingfrequencyfsw=10kHzCollectorEmittervoltageVCE=1200VNumberofdriverchannels:2(GBmodule)dualdriverComparisonwiththeparametersinthedriverdatasheetCalculatedandappliedvalues:Ig.pulse=2.9A

@Rg=7+RintIoutAV=13.9mAfsw=10kHzVCE=1200VQG=1390nCAccordingtotheappliedandcalculatedvalues,thedrivere.g.SKHI22AisabletodriveSKM200GB128DPCBDriverandPCBmountableDriverforsingle,halfbridge,sixpackmodulesintegratedpotential-freepowersupplyswitchingfrequencyupto100kHzoutputpeakcurrentupto30AGatechargeupto30µCdv/dtcapabilityupto75kV/µshighEMIimmunityTTL-anCMOS-compatibleinputsandoutputswithpotentialisolationviaoptocouplerortransformer(isolationupto4kVAC)protection(interlock,shortpulsesuppression,shortcircuitprotectionviaVCE-monitoring,undervoltagemonitoring,errormemoryanderrorfeedback)SEMIDRIVERProductoverview(importantparameters)DrivercoreforIGBTmodulesSimpleAdaptableExpandableShorttimetomarketTwoversionsSKYPER™(standardversion)SKYPER™PRO(premiumversion)AssemblyonSEMiXTM3–ModularIPMSKYPER

DriverboardSEMIX3IGBThalfbridgewithspringcontactsSKYPER™–morethanasolutionmodularIPMusingSEMiX®withadapterboardsolderdirectlyinyourmainboardtake3for6-packs

SelectionoftherightIGBTdriverAdviceProblem1---------------------CrossconductionLowimpedanceCrossconductionbehaviorvCE,T1(t)iC,T1(t)VCCIO0tvGE,T1(t)vGE,T2(t)VGE,IoVGE(th)0tVGG+VCCIO0tvCE,T2(t)=

vF,D2(t)iF,D2(t),

iC,T2(t)T1D1T2D2iv,T2Whychanges

VGE,T2whenT1switcheson?

IGBT-ParasiticcapacitancesWhentheoutervoltagepotentialVchanges,theloadQhastofollowThisleadstoadisplacementcurrentiV

Switching:DetailedforT2iv,T2vCE,T2vGE,T2iC,T2RGE,T2CGC,T2vCE,T2(t)VCC0t0tiC,T2(t)iv,T2(t)vGE,T2(t)VGE(th)0tVGG+DiodeD2switchesoffandtakesoverthevoltageT2“sees”thevoltageoverD2asvCE,T2Withthechangedvoltagepotential,theinternalcapacitanceschangetheirchargeThedisplacementcurrentiv,T2flowsviaCGC,T2,RGE,T2andthedriveriv,T2causesavoltagedropinRGE,T2whichisaddedtoVGE,T2IfvGE,T2>VGE(th)thenT2turnson(ThereforeSKrecommends:VGG-=-5…-8…-15V)Problem2-----------------------------gateprotectionZ16-18Gateclamping----how?Z18PCBdesignbecausenocableclosetotheIGBTProblem3-----------------boosterforthegatecurrentUseMOSFETfortheboosterForsmallIGBTsisokProblem4----------------------------ShortcircuitOvervoltage1200V-----ischiplevel----considerinternalstrayinductance+/-20V-----gateemittervoltage----considerswitchingbehavioroffreewheelingdiodeOvercurrentPowerdissipationofIGBT(shortcircuitcurrentxtime)ChiptemperaturelevelProblem5–deadtimebetweentopandbottomIGBTTurnonan