電力電子裝置及系統(tǒng) 課件 Topic 6-Multilevel cascaded H-bridge inverter、Topic 7-Multilevel neutral point clamped inverter_第1頁
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Topic6:MultilevelcascadedH-bridgeinverter1CHBInverterFedDriveH-bridepowercellsSource:Toshiba-GeneralElectricTopic6:MultilevelCHBinverterH-BridgeInverterCHBInverterTopologiesPhaseShiftedPWMLevelShiftedPWMPWMSchemeComparison2Topic6:MultilevelCHBinverter3WhyUseMultilevelInverters??Toincreaseinverteroperatingvoltagewithoutdevicesinseries?TominimizeTHDwithlowswitchingfrequenciesfsw?ToreduceEMIduetolowervoltagestepsSwitchingfrequencyforhighpowerconverters:fsw=60Hz~1000HzMultilevelInverterTopologies4Per-PhaseDiagramH-BridgeInverter5H-bridgePowerCellH-BridgeInverter6TypicalIndustrialApplicationsFive-levelCHBinverterH-bridgePowerCellH-BridgeInverter7BipolarModulationBipolarPWM:vABfrom-Vdto+Vdorfrom+Vdto-VdH-BridgeInverter8BipolarModulation(FFT)H-BridgeInverter9UnipolarModulation(1)?Twomodulationwavesvmandvm-?Onecarrierwavevcr?UnipolarPWM:vABfrom0to+Vdorfrom0to-VdH-BridgeInverter10UnipolarModulation(2)?Onemodulationwaves:vm?Twocarrierwave:vcr

andvm-CHBInverterTopologies11Five-LevelCHBInverterComplementarySwitchpairs:S11andS41;S31andS21;S12andS42;S32andS22;Note:Convertersincascade,butnoswitchingdevicesinseries.CHBInverterTopologies12OutputVoltageandSwitchingStatus(five-level)WaveformofvANiscomposedoffivevoltagelevels:2E,E,0,-E,and-2E.CHBInverterTopologies13Seven-andNine-LevelInverters(Perphasediagram)CHBInverterTopologies14UnequaldcBusVoltagesCHBInverterTopologies15UnequaldcBusVoltages(Two-cellseven-leveltopology)PhaseShiftedPWM16CarrierBasedPWM–PhaseShifted?#ofvoltagelevels:m=7?#ofcarriers:mc=m-1=6?Phaseshift:360°/mc=60°CarriersforH1bridge: vcr1andvcr1-CarriersforH2bridge: vcr2andvcr2-CarriersforH3bridge: vcr3andvcr3-m=7PhaseShiftedPWM17InverterWaveforms(7-level,phaseshifted)?Switchingoccursatdifferenttimes?fsw(device)=60mf=600Hz?Inverterphasevoltagelevels:7?LowEMI?Line-to-linevoltagelevels:13?Closetoasinusoid?LowTHDPhaseShiftedPWM18FFT(7-level,phaseshifted)?Lowestharmonics:around2mf?Lowestharmonics:around6mf?ContainingtriplenHarmonics?Notriplen

harmonics?Equivalentfsw(inverter)=60(6mf)=3600HzPhaseShiftedPWM19HarmonicContent(7-level,phaseshifted)LevelShiftedPWM20CarrierBasedPWM–LevelShifted?#ofvoltagelevels:

m=5?#ofcarriers:

mc=m-1=4Note:IPDprovidesthebestharmonicprofile.IPD:APOD:POD:LevelShiftedPWM21GatingArrangement(7-level)?#ofvoltagelevels:m=7?#ofcarriers:mc=m-1=6?fsw(device):-notequaltofcr,and-notthesameforallswitches.?Deviceconductionangle:-notequal.?Necessarytoswapswitchingpattern.LevelShiftedPWM22InverterOutputVoltages(7-level)?m=7?Switchingoccursatdifferenttimes?fsw(device)=fcr/mc=600Hz(avg)?vABclosetoasinusoid?LowTHD,lowEMI?fsw(inv)=fc=3600HzLevelShiftedPWM23PrototypeatRyerson(7-levelCHB)LevelShiftedPWM24MeasuredWaveforms(IPD,7-levelCHB)InverterphasevoltagevANLine-to-linevoltagevABPWMSchemeComparison25PWMatLowma?Atma=0.2:-PhaseshiftedPWM:THD=96.7%-LevelshiftedPWM:THD=48.8%PWMSchemeComparison26TotalHarmonicDistortion(THD)PWMSchemeComparison27SummaryTopic7:MultilevelNeutralPointClampedInverter28Three-LevelNPCInverterBasedMVDriveSource:ABB(ACS1000)Topic7:MultilevelNPCInvertersThree-levelNPCInverterSpaceVectorModulationNeutralPointVoltageControlHigh-levelNPCInverters29MultilevelInverterTopologies30Per-PhaseDiagramMultilevelNPCInverters31InverterConfigurationClampingdiodes:DZ1andDZ2(PhaseA)MultilevelNPCInverters32SwitchingStateComplementarySwitchpairs:S1andS3;S2andS4;MultilevelNPCInverters33GateSignalArrangementsInverterphasevoltagevAZhasthreelevels:E,0and–EMultilevelNPCInverters34InverterOutputWaveformsSpaceVectorModulation35SpaceVectors?Three-phasevoltages

(1)?Two-phasevoltages(2)?Spacevectorrepresentation(3)(2)(3)

(4)whereSpaceVectorModulation36SpaceVectors(Example)Switchingstate[POO]on-stateswitches:PhaseA:uppertwoswitches[P]PhaseB:middletwoswitches[O]PhaseC:middletwoswitches[O]Fromwhich

and

(5)?Substituting(5)to(4)givesaspacevector(6)Totalswitchingstates:27Totalspacevectors:19SpaceVectorModulation37SpaceVectorsDiagram19spacevectors:Zerovector:V0Smallvectors:V1–V6Mediumvectors:V7–V12Largevectors:V13–V18SpaceVectorModulation38SwitchingStatesandSpaceVectorsRedundancy:Zerovector–threeswitchingstatesSmallvectors–twostatespervectorSpaceVectorModulation39SwitchingStatesandSpaceVectorsNoredundantswitchingstatesformediumorlargevectorsSpaceVectorModulation40SectorDefinition?Vref:Referencevector,rotatinginspaceatacertainspeed;?Allothervectorsarestationary.SpaceVectorModulation41SVMPrinciple?Foragivenlengthandpositioninspace,Vrefcanbeapproximatedbythreenearbystationaryvectors;?Basedonthechosenstationaryvectors,switchingstatesareselectedandgatesignalsaregenerated;?WhenVrefpassesthroughsectorsonebyone,differentsetsofswitchesareturnedonoroff;?WhenVrefrotatesonerevolutioninspace,theinverteroutputvoltagevariesonecycleovertime;?TheinverteroutputfrequencycorrespondstotherotatingspeedofVref;?TheinverteroutputvoltagecanbeadjustedbythemagnitudeofVref.SpaceVectorModulation42SectorDefinition?Vref:Referencevector,rotatinginspaceatacertainspeed;?Allothervectorsarestationary.SpaceVectorModulation43DwellTimeCalculationDwelltimeistheduty-cycletimeofselectedswitchesduringthesamplingperiodTs.?Selectthreeneareststationaryvectors?Usevolt-secondbalancingprinciple(a)SectorIFourRegionsSpaceVectorModulation44DwellTimeCalculation?Fromequation(a)Ta,TbandTc–dwelltimesforV1,V7andV2–modulationindex

SpaceVectorModulation45SwitchingSequence(Seven-segment)?GeneralDesignRequirementsa)Thetransitionfromoneswitchingstatetothenextinvolvesonlytwoswitchesinthesameinverterleg,onebeingturnedonandtheotherturnedoff;andb)ThetransitionforVrefmovingfromonesector(oroneregion)tothenextrequiresnoorminimumnumberofswitchings.Note:Theswitchingsequencedesignisnotunique,buttheaboverequirementsshouldbesatisfiedforswitchingfrequencyminimization.SpaceVectorModulation46SwitchingSequence(Seven-segment)?AssumingVrefisinRegion4ofSectorI,threevectorsareselected:V2,V7andV14SpaceVectorModulation47SwitchingSequence(Seven-segment)Note:Switchingsequencerequirementa)issatisfied.SpaceVectorModulation48SwitchingSequence(Seven-segment)SpaceVectorModulation49SwitchingSequence(Seven-segment)Note:Switchingsequencerequirementb)issatisfied.?Deviceswitchingfrequency:?Samplingfrequency:?Fundamentalfrequency:SpaceVectorModulation50SimulatedWaveforms(Seven-segment)?Deviceswitchingf1=60Hz,Ts=1/1080sec,ma=0.8,fsw=570Hz?vABisnothalfwavesymmetrical;andcontainsbotheven-andodd-orderharmonics.SpaceVectorModulation51SimulatedWaveforms(Seven-segment)f1=60Hz,Ts=1/1080sec,ma=0.8,fsw=570HzSpaceVectorModulation52HarmonicContent(Seven-segment)SpaceVectorModulation53LaboratoryPrototypeatRyersonSpaceVectorModulation54MeasuredWaveformsSpaceVectorModulation55MeasuredWaveforms(witheven-orderharmonicelimination)NeutralPointVoltageControl56NeutralPointVoltageDeviationTheneutralpointvoltagevzcanbecontrolledbyP-andN-typesofsmallvectorsNeutralPointVolt

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