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I&PCDiv.-Off-lineSMPSAppl.LabMLDGROUPINDUSTRIAL&POWERCONVERSIONDIVISIONOff-lineSMPSBUApplicationLabSimplifiedAnalysisandDesignofSeries-resonantLLCHalf-bridgeConverters第1页I&PCDiv.-Off-lineSMPSAppl.LabPresentationOutline•LLCseries-resonantHalf-bridge:operationandsignificantwaveforms•Simplifiedmodel(FHAapproach)•300Wdesignexample第2页I&PCDiv.-Off-lineSMPSAppl.LabSeries-resonantLLCHalf-BridgeTopologyandfeaturesHalf-bridgeDriverVinCrVoutMulti-resonantLLCtankcircuitVariablefrequencycontrolFixed50%dutycycleforQ1&Q2Dead-timebetweenLGandHGtoallowMOSFET’sZVS@turn-onfsw≈fr,sinusoidalwaveforms:lowturn-offlosses,lowEMIEqualvoltage¤tstressforsecondaryrectifiers;ZCS,thennorecoverylossesNooutputchoke;costsavingIntegratedmagnetics:bothL’scanberealizedwiththetransformer.Highefficiency:96%achievableLLCtankcircuitLsLpPreferablyintegratedintoasinglemagneticstructureVoutCenter-tappedoutputwithfull-waverectification(lowvoltageandhighcurrent)Single-endedoutputwithbridgerectifiication(highvoltageandlowcurrent)fr112π⋅LsCr⋅⋅fr212π⋅LsLp+()Cr⋅⋅3reactiveelements,2resonantfrequenciesfr1fr2Q1Q2第3页I&PCDiv.-Off-lineSMPSAppl.LabLLCResonantHalf-bridgeWaveformsatresonance(fsw=fr1)Gate-drivesignalsTransformercurrentsDead-timeDiodevoltagesDiodecurrentsMagnetizingcurrentistriangularOutputcurrentTankcircuitcurrentissinusoidalCCMoperationHBmid-pointVoltageResonantcapvoltage第4页I&PCDiv.-Off-lineSMPSAppl.LabLLCResonantHalf-bridgeSwitchingdetailsatresonance(fsw=fr1)Gate-drivesignalsTransformercurrentsDiodevoltagesDiodecurrentsDead-timeZVS!ZCS!MagnetizingcurrentTankcircuitcurrent0I(D1)=0V(D1)0HBmid-pointVoltageResonantcapvoltage第5页I&PCDiv.-Off-lineSMPSAppl.LabLLCResonantHalf-bridgeOperatingSequenceatresonance(Phase1/6)Q1ONQ2OFFQ1OFFQ2ONQ1OFFQ2ON1/6VinVoutQ1Q2LsLpCrn:1:1D1D2Coss1Coss2Q1isOFF,Q2isOND1isOFF,D2isON;V(D1)=-2·VoutLpisdynamicallyshorted:V(Lp)=-n·Vout.CrresonateswithLs,fr1appearsOutputenergycomesfromCrandLsPhaseendswhenQ2isswitchedoffCout第6页I&PCDiv.-Off-lineSMPSAppl.LabQ1ONQ2OFFQ1OFFQ2ONQ1OFFQ2ONLLCResonantHalf-bridgeOperatingSequenceatresonance(Phase2/6)VinVoutQ1Q2LsLpCrn:1:1D1D2Coss1Coss2Q1andQ2areOFF(dead-time)D1andD2areOFF;V(D1)=V(D2)=0;transformer’ssecondaryisopenI(Ls+Lp)chargesCOSS2anddischargesCOSS1,untilV(COSS2)=Vin;Q1’sbodydiodestartsconducting,energygoesbacktoVinI(D2)isexactlyzeroatQ2switchoffPhaseendswhenQ1isswitchedonCout2/6第7页I&PCDiv.-Off-lineSMPSAppl.LabQ1ONQ2OFFQ1OFFQ2ONQ1OFFQ2ONLLCResonantHalf-bridgeOperatingSequenceatresonance(Phase3/6)VinVoutQ1Q2LsLpCrn:1:1D1D2Coss1Coss2Q1isON,Q2isOFFD1isON,D2isOFF;V(D2)=-2·VoutLpisdynamicallyshorted:V(Lp)=n·Vout.CrresonateswithLs,fr1appearsI(Ls)flowsthroughQ1’sRDS(on)backtoVin(Q1isworkinginthe3rdquadrant)PhaseendswhenI(Ls)=0Cout3/6第8页I&PCDiv.-Off-lineSMPSAppl.LabQ1ONQ2OFFQ1OFFQ2ONQ1OFFQ2ONLLCResonantHalf-bridgeOperatingSequenceatresonance(Phase4/6)4/6VinVoutQ1Q2LsLpCrn:1:1D1D2Coss1Coss2Q1isON,Q2isOFFD1isON,D2isOFF;V(D2)=-2·VoutLpisdynamicallyshorted:V(Lp)=n·Vout.CrresonateswithLs,fr1appearsI(Ls)flowsthroughQ1’sRDS(on)fromVintogroundEnergyistakenfromVinandgoestoVoutPhaseendswhenQ1isswitchedoffCout第9页I&PCDiv.-Off-lineSMPSAppl.LabQ1ONQ2OFFQ1OFFQ2ONQ1OFFQ2ONLLCResonantHalf-bridgeOperatingSequenceatresonance(Phase5/6)5/6VinVoutQ1Q2LsLpCrn:1:1D1D2Coss1Coss2Q1andQ2areOFF(dead-time)D1andD2areOFF;V(D1)=VD(2)=0;transformer’ssecondaryisopenI(Ls+Lp)chargesCOSS1anddischargesCOSS2,untilV(COSS2)=0;Q2’sbodydiodestartsconductingI(D1)isexactlyzeroatQ1switchoffPhaseendswhenQ2isswitchedonCout第10页I&PCDiv.-Off-lineSMPSAppl.LabQ1ONQ2OFFQ1OFFQ2ONQ1OFFQ2ONLLCResonantHalf-bridgeOperatingSequenceatresonance(Phase6/6)6/6VinVoutQ1Q2LsLpCrn:1:1D1D2Coss1Coss2Q1isOFF,Q2isOND1isOFF,D2isONLpisdynamicallyshorted:V(Lp)=-n·Vout.CrresonateswithLs,fr1appearsI(Ls)flowsthroughQ2’sRDS(on)(Q2isworkinginthe3rdquadrant)OutputenergycomesfromCrandLsPhaseendswhenI(Ls)=0,Phase1startsCout第11页I&PCDiv.-Off-lineSMPSAppl.LabLLCResonantHalf-bridgeWaveformsaboveresonance(fswfr1)Gate-drivesignalsTransformercurrentsDead-timeDiodevoltagesDiodecurrentsMagnetizingcurrentistriangularOutputcurrentTankcircuitcurrentCCMoperationHBmid-pointVoltageResonantcapvoltageSinusoid@f=fr1~Linearportion第12页I&PCDiv.-Off-lineSMPSAppl.LabLLCResonantHalf-bridgeSwitchingdetailsaboveresonance(fswfr1)Gate-drivesignalsTransformercurrentsDiodevoltagesDiodecurrentsDead-timeZVS!ZCS!OutputcurrentMagnetizingcurrentTankcircuitcurrent0I(D1)=0V(D1)0Slope~-(Vc-n·Vout)/LsHBmid-pointVoltageResonantcapvoltage第13页I&PCDiv.-Off-lineSMPSAppl.LabLLCResonantHalf-bridgeOperatingSequenceaboveresonance(Phase1/6)Q1ONQ2OFFQ1OFFQ2ONQ1OFFQ2ON1/6VinVoutQ1Q2LsLpCrn:1:1D1D2Coss1Coss2Q1isOFF,Q2isOND1isOFF,D2isON;V(D1)=-2·VoutLpisdynamicallyshorted:V(Lp)=-n·Vout.CrresonateswithLs,fr1appearsOutputenergycomesfromCrandLsPhaseendswhenQ2isswitchedoffCout第14页I&PCDiv.-Off-lineSMPSAppl.LabLLCResonantHalf-bridgeOperatingSequenceaboveresonance(Phase2/6)VinVoutQ1Q2LsLpCrn:1:1D1D2Coss1Coss2Q1andQ2areOFF(dead-time)D1andD2areOFF;V(D1)=V(D2)=0;transformer’