IGBT门极电阻设计

ApplicationNoteRevision:IssueDate:Preparedby:002007-11-12MarkusHermwilleKeyWords:IGBTdriver,gateresistor,selection,design,applicationGateResistor–PrinciplesandApplicationsAN-70031/102007-11-12–Rev00©bySEMIKRONIntroduction.............................................................................................................................................................................1IGBTSwitchingBehaviour......................................................................................................................................................2SwitchingBehaviourofFree-WheelingDiode........................................................................................................................4DrivingOutputStage..............................................................................................................................................................4GateResistorDimensioning...................................................................................................................................................5MinimumGateResistance–MaximumGatePeakCurrent...................................................................................................6PowerDissipation...................................................................................................................................................................6PeakPowerCapability...........................................................................................................................................................7ResistorType.........................................................................................................................................................................7DesignandLayout.................................................................................................................................................................7Troubleshooting......................................................................................................................................................................9SymbolsandTermsUsed......................................................................................................................................................9References...........................................................................................................................................................................10Thisapplicationnoteprovidesinformationontheuseofgateresistors(RG)tocontrolIGBTswitching.Theinformationgiveninthisapplicationnotecontainstipsonlyanddoesnotconstitutecompletedesignrules;theinformationisnotexhaustive.Theresponsibilityforproperdesignremainswiththeuser.IntroductionTheswitchingbehaviourofpowersemiconductorsiscontrolledbythegatecapacitancerecharge.Thisgatecapacitancerechargemaybecontrolledviaagateresistor.Byusingatypicalpositivecontrolvoltage(VG(on))of+15VtheIGBTisturned-onandturned-offatanegativeoutputvoltage(VG(off))oftypically-5…-8…-15V.ThedynamicIGBTperformancecanbeadjustedbythevalueofthegateresistor.ThegateresistorinfluencestheIGBTswitchingtime,switchinglosses,reversebiassafeoperatingarea(RBSOA),short-circuitsafeoperatingarea(SCSOA),EMI,dv/dt,di/dtandreverserecoverycurrentofthefree-wheelingdiode.Ithastobeselectedandoptimizedverycarefullyinaccordancewiththeindividualapplicationparameters,e.g.IGBTtechnology,diode,switchingfrequency,losses,applicationlayout,inductivity/strayinductance,DC-linkvoltageanddrivercapability.Thecompletedesignofanapplicationmustbeviewedasawhole,withdueconsideringoftheabove-mentionedparameters.Interactiveeffectswithinthewholeapplicationmustbeevaluatedandaccommodated.ControlbyResistance–Rev00©bySEMIKRONIGBTSwitchingBehaviourTheswitchingbehavioursettingofeachIGBTcanbeaffectedbytheexternalresistorRG.AstheinputcapacitanceofanIGBT,whichvariesduringswitchingtime,hastobechargedanddischarged,thegateresistorwilldictatewhattimeisneededtodothisbylimitingthemagnitudeofthegatecurrent(IG)pulsesduringturn-onandturn-off.Turn-onGateCurrentTurn-offGateCurrentRG(off)VG-IGDuetotheincreaseinthegatepeakcurrent,whichisaffectedbyreducingtheresistorvalueRG(on)andRG(off),theturn-onandturn-offtimewillbeshorterandtheswitchinglosseswillbereduced.Thefollowingdiagramsshowswitchinglossesandswitchingtimesdependingontheselectedgateresistorvalue.Turn-on/-offEnergy=f(RG)(e.g.SKM200GB128D)SwitchingTimesvs.RateResistor(e.g.SKM200GB128D)Whatneedstobeconsideredwhenreducingthevalueofthegateresistoristhedi/dtgeneratedwhenhighcurrentsareswitchedtoofast.Thisisduetostrayinductancepresentinthecircuit,whichproducesahighvoltagespikeontheIGBT.Thissurgevoltagecanbeestimatedusingthefollowingequation.EquationforVoltageSpikedtdiLVstray×=σThiseffectcanbeobservedinthewaveformshownforIGBTturn-off.Theshadedareasshowtherelativevalueoftheswitchinglosses.Thetransientvoltagespikeontopofthecollector-emittervoltagemaydestroytheIGBT,espe