Comparative Evaluation of Advanced 3-level Inverte

ComparativeEvaluationofAdvanced3-levelInverter/ConverterTopologiesagainst2-levelSystemsM.Schweizer,T.Fried[e-mail]@lem.ee.ethz.chOutlineIntroduction3-levelT-typeconvertertopology3-levelNPCtopologywithSiCdiodesModulationandDC-linkbalancingComparisonofpassivesComparisonofsemiconductorchipareaOptimizationpotential[e-mail]33-phase3-leveltopologiesforlowvoltageapplications-abadidea?Butisthisthefullstory?Alternative,suitable3-levelconceptsEnhancementswithSiCdiodesNecessarysemiconductorchipareaOptimizationforoperatingpointAC-ACconverterDC-linkbalancingMoresemiconductorsMoregatedriveunitsIncreasedcomplexityDC-linkbalancingIncreasedcosts!Highefficiencyatincreasedswitchingfrequency[e-mail]econvertertopologies42-levelVSCSimple,lowpartcount,robust,cheapReductionofswitchinglosseswithSiCdiodes3-levelT-type3bidirectionalswitchestomiddlevoltage3-levelNPCEnhancementwithSiCdiodes?AC-ACconverters[e-mail]2-levelvoltagesourceconverterHighswitchinglossesMeanlossdistributionissimilarforrectifierandinverteroperation5Rectifieroperation2-level1200VIGBT:InfineonIKW25T120InverteroperationPn=10kW,Udc=700V,Ûn=325V,În=20.5A,j=0/180°ClearbenefitfromSiCdiodeslossreduction:[e-mail]3-levelT-type–AnalternativeVSCtopologySimpleextensionoftheconventional2-leveltopologytoa3-leveltopology?6BidirectionalmiddleswitchwithtwoIGBTsincommonemitterconnection600Vdevices1200VdevicesCombinationof1200Vand600Vdevices600VIGBT:lowswitchinglosses,lowforwardvoltagedropOnlyonemoreisolatedgatedrivesupplyperphaseleg(comparedto2-level)[e-mail]-typetopology-commutationCurrentindependentcommutationsequence7T1T2T3T4P110000110N0011TransitionP→0,Iout01)T1&T2closed,T3&T4open2)T1opens-Ioutcomm.to0overD3&T23)T3closesafterturn-ondelayTdTransitionP→0,Iout01)T1&T2closed,T3&T4open2)T1opens3)T3closesafterturn-ondelayTdIoutcomm.to0overT3&[e-mail]-typetopology–losscalculation8SwitchinglosseschangebecauseofmixedIGBTtypesLossenergymeasuredwithT-typebridgelegtestsetup1200VIGBT:InfineonIKW25T120600VIGBT:InfineonIKW30N60T@300V,20A,125°CPn=10kW,Ûn=325V,În=20.5A,j=0/180°RectifieroperationInverteroperationReducedswitchinglossesCommutationvoltageisonlyUdc/2D[e-mail]3-levelNPCconverter9600Vdevices:Lowswitchinglosses,lowforwardvoltagedropOptimalclampingpossibleReductionofswitchinglossesDC-linkbalancingisrestrictedCanweimprovethe3-levelNPCconverter?SiCdiodes[e-mail]3-levelNPCconverterwithSiCdiodes10ShouldwereplacealldiodeswithSiC?Veryexpensive!IncreasedconductionlossesCustomSiC3-levelNPCbridgelegmoduleSi3-levelNPCModulationAnalysisofoccuringlossenergiesDirecttransitionPNorNPisomittedD2andD3nevershowreverserecoveryeffect!LeaveitinconventionalSi!ConsidercharacteristiclossdistributionInverteroperation(solarinverter)ReplaceonlyD5andD6withSiCdiodesRectifieroperation(pfcgridinterface)[e-mail]11Rectifieroperation600VIGBT:InfineonIKW30N60TInverteroperationPn=10kW,Udc=700V,Ûn=325V,În=20.5A,j=0/180°ReplaceD1andD4withSiCIKW30N60T+CreeCSD10060scaledto30A[e-mail]ison122-levelisefficientforlowswitchingfrequencySiCdiodescanextendfsrangePn=10kW,Udc=700V,Ûn=325V,În=20.5A,j=0/180°RectifieroperationInverteroperationT-typetopologyisveryefficientformediumfs(8–20kHz)3-levelNPCefficiencyhasflattestdependencyonfsSuitableforhighfsSiCdiodesmakeonlysenseforveryhighfs(50kHz)[e-mail]torchiparea13Non-uniformdistributionoflossesoverthesemiconductorchipsLowlossesinadeviceMakechipsmallerHighlossesinadeviceMakechipbiggerReachTj=125°CineachchipIdea:OperatingpointdependentchipsizeoptimizationFairtopologycomparisonReducemodulecostsCheapmassmarketmodules:Pureinverter/rectifier3-levelmodulesforfixedoperatingpoint(solarinverter/pfc)[e-mail]Tj=125°C142-leveltopologyLossesareconcentratedinfewchipsChipsizeincreasessharplywithfrequencyTotalchipareaof2-levelissmallestonlyforlowswitchingfreq.(fs10kHz)!3-leveltopologiesLossesaredistributedovermanysemiconductorsChipsizereductionpossibleLossesincreaseonlyslightlywithfsDistinctlossprofile(Operatingpoint)Totalsemiconductorarea:Forfs=35kHz:A2-level≈2*A3-lvlNPC![e-mail]=125°C(rectifieroperation)1548162448fs[kHz]SwitchingfrequencyTotalarea[mm2](3phases)85.194.7102.2100.7(+18%)98.9(+4%)103.8(+2%)137.4(+61%)108.0(+14%)107.2(+5%)177.4(+108%)117.9(+24%)110.9(+9%)302.3(+2