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三电平逆变器共模电压分析与抑制.docx

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三电平逆变器共模电压分析与抑制 Title:AnalysisandSuppressionofCommonModeVoltageinaThree-LevelInverter Abstract: Withtheincreasingdemandforhigherpowerconversionefficiencyandreducedharmonicdistortion,three-levelinvertershavegainedsignificantattentioninvariousindustrialapplications.However,commonmodevoltage(CMV)arisesasamajorconcernintheseinverters,asitcancauseavarietyofissues,includingmotorinsulationdegradationandelectromagneticinterference(EMI)problems.Therefore,thispaperfocusesonanalyzingtheCMVinathree-levelinverterandproposeseffectivemethodstosuppressit. 1.Introduction: Inrecentyears,three-levelinvertershavebeenwidelyusedinvariouspowerconversionsystemsduetotheirabilitytoreducevoltagestressonswitches,reduceharmonics,andimproveoverallsystemefficiency.However,thepresenceofCMVintheseinverterscanleadtodetrimentaleffects.CMVisthevoltagepotentialbetweenthesystem'sneutralpointandtheground,whichcancausecapacitivecouplingwiththemotorwindingsandcreatevoltagestressonmotorbearings.Furthermore,CMVcanleadtoEMIissuesandaffecttheperformanceofotherelectronicdevicesinthesystem.Therefore,analyzingandsuppressingCMVisofparamountimportancetoensurethereliableoperationofthree-levelinverters. 2.CausesandEffectsofCommonModeVoltage: 2.1.VoltageImbalance: OneofthemainsourcesofCMVinathree-levelinverterisvoltageimbalanceintheDClinkcapacitors.Duetomanufacturingtolerancesandcomponentmismatches,theDCvoltagesacrossthecapacitorsmaynotbeperfectlybalanced,leadingtounequalvoltagedistributionsbetweentheneutralpointandground. 2.2.SwitchingTransients: SwitchingtransientsalsocontributetoCMVinthree-levelinverters.Duringtheswitchingprocess,highdv/dtoccurs,causingvoltagespikesandresultinginexcessiveCMV. 2.3.RelayParasiticCapacitance: ThepresenceofrelayparasiticcapacitancecanleadtoCMVintheinvertersystem,asitformsacapacitivecouplingbetweentheinvertercircuitandtheground. TheeffectsofCMVincludemotorbearingfailures,reducedmotorinsulationlife,increasedEMI,andtransformeroverheating.Therefore,effectiveCMVsuppressiontechniquesareneces