Active-Neutral-Point-Clamped(ANPC)MultilevelConverterTechnologyPeterBarbosa1,PeterSteimer2,JürgenSteinke2,ManfredWinkelnkemper1,andNikolaCelanovic11ABBSwitzerlandLtdCorporateResearchSegelhof15405Dättwil2ABBSwitzerlandLtdPowerElectronicsandMVDrivesAustrasse5300TurgiAcknowledgmentTheauthorswouldliketothanktheOfficeofNavalResearchforsupportingpartofthisworkunderAgreementN00014-99-3-0002“VeryHighPowerPEBBDemonstration.”Keywords«Multilevelconverters»,«powerquality»,«harmonics»,«modulationstrategy»,«voltagesourceinverters(VSIs)»AbstractThispaperproposesamultilevelpowerconversionconceptbasedonthecombinationofneutral-point-clamped(NPC)andfloatingcapacitorconverters.Intheproposedscheme,thevoltagebalancingacrossthefloatingcapacitorsisachievedbyusingaproperselectionofredundantswitchingstates,andtheneutral-pointvoltageiscontrolledbytheclassicaldcoffsetinjection.Experimentalresultsareillustratedinthepapertodemonstratethesystemoperation.IntroductionMultileveltopologiesprovideacleverwayofconnectingswitchesinseries,thusenablingtheprocessingofvoltagesthatarehigherthanthedevicerating.Theindustryneedformediumvoltagedriveshastriggeredconsiderableresearchinthisfield,inwhichmostapplicationsincludedrivesforpumps,blowers,compressors,conveyors,andthelike.Ingeneral,multilevelconvertersareeffectivemeansofreducingharmonicdistortionanddv/dtoftheoutputvoltages,whichmakesthistechnologyapplicabletoutilityinterfaceanddrives.Therearealimitednumberoftopologiesthatprovidemultilevelvoltagesandaresuitableformediumvoltageapplications.Themostknowntopologiesaretheneutral-point-clamped(NPC),theflyingcapacitor(FC),andthecascadedH-bridgemultilevelconverters[1][2][3][4].Othertopologiessuchasthehybridconvertershavebeenproposedaswell,buttheyarenotfullyacceptedforindustrialapplications[5][6].TheNPCmultilevelconvertershowninFigure1(a)isanaturalextensionofthethree-levelconverterpresentedbyNabae(NPC3L).Ascanbeseen,themultilevelNPCconverterrequiresmultipleclampingpointstosynthesizethedifferentvoltagelevelsacrosstheoutput.Thedisadvantageofmultipleclampingpointsisalimitationonthemaximummodulationindexthatisallowedwithactivepowertoassurevoltagesharingacrossallthedclinkcapacitors[7].AnotherdrawbackofthemultilevelNPCconverteristheneedforseriesconnectionoftheclampingdiodes[8].Figure1(b)illustratesafive-levelfloatingcapacitorconverter.Byproperlyusingthedclinkandfloatingcapacitorvoltages,onecansynthesizetherequiredvoltagelevelsacrosstheoutputterminals.Aninterestingpropertyofthefloatingcapacitorconverteristhattheredundantswitchingstatescanbeusedtoachievepropervoltagecontrolacrossthefloatingcapacitors.Ingeneral,theenergystoredinthefloatingcapacitorsisalimitingfactortoincreasingthenumberofvoltagelevels,whichmakesthefive-levelapproachthemostpracticalforindustrialapplications.AnincreasednumberofvoltagelevelsmayonlybepracticalfromtheviewpointoffloatingcapacitorrequirementsiftheActive-Neutral-Point-Clamped(ANPC)MultilevelConverterTechnologyBARBOSAPeterEPE2005-DresdenISBN:90-75815-08-5P.1carrierfrequencyoftheconverterisincreased.However,therearetradeoffsthatshouldbeobservedbetweencarrierfrequencyandswitchinglossesintheconverter.ThecascadedH-bridgemultilevelconvertershowninFigure1(c)takesadvantageofconnectingsingle-phaseinvertersinseriesthatarefedbyindependentdcvoltagesources.Theapproachcanbeextremelymodular,andastair-casedoutputvoltageisproducedbyaddingand/orsubtractingthevoltagesofthesingle-phasemodules.Thepowerflowmaybebi-directionalifactivefront-endrectifiersareusedinthesingle-phasemodules.Althoughmodular,thecascadedH-bridgemultilevelconverterrequiresacomplextransformertoprovidethevariousindependentdcsources.Baseduponthepreviousdescription,thispaperproposesanactiveneutral-point-clamped(ANPC)multilevelconverterthatcombinestheflexibilityofthemultilevelfloatingcapacitorconverterwiththerobustnessofindustrialNPCconverterstogeneratemultilevelvoltages.Theproposedconceptisdescribedandsupportedbysimulationresults,andexperimentalvalidationdemonstratestheproposedtechnology.ProposedconceptTheproposedconceptisshowninFigure2(a),whichisnamedactive-neutral-point-clampedfive-level(ANPC5L)converter.Ascanbeseen,theproposedconverterisanarrangementoftwo-levelinvertersconnectedinseries.Twoofsuchsubsystemsareconnectedinparallelwiththedc-linkcapacitors.ThefirstsubsystemiscomprisedofS5,S6,S9,S10,andC2,whilethesecondsubsystemiscomprisedofS7,S8,S11,S12,andC3.Athirdsubsystem(S1,S2,S3,S4,andC1)isthenusedtoconnecttheconvertertotheoutputphase.Ingeneral,anN-levelconvertercanbeobtainedbycascading(N-1)/2two-levelinverterspersubsystemaccordingtoFigure2(a).Acarrier-basedPWMstrategycanbeusedtogeneratethepulsepattern,asshowninFigure2(b)[9].Fourtriangularcarriersareusedandphase-shiftedby90°.ThefirstcarriergeneratespulsestoS1andS2,thesecondcarriertoS3andS4,thethirdcarriertoS5,S6,S7,andS8,andthefourthcarriertoS9,S10,S11,andS12.ItisworthmentioningthattheswitchesS5andS7areoperatedinphase,andwhileS6andS8arealsoinphase,theyarecomplementarytoS5andS7.AsimilarsequenceisappliedtoS9,S10,S11,andS12.Theresultingnormalized
本文标题:Active-Neutral-Point-Clamped-(ANPC)-Multilevel-Con
链接地址:https://www.777doc.com/doc-1386618 .html