电气专业毕设英文文献格式已修改.docx

电气专业毕设英文文献格式已修改.docx

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电气专业毕设英文文献格式已修改

本科毕业设计

外文文献及译文

文献题目：

DirectTorqueControlofInductionMotorsUtilizingThree-LevelVoltageSourceInverters

文献作者：

XavierdelToroGarcia,AntoniArias,MarcelG.JayneandPhilA.Witting

文献来源：

IEEETrans.Ind.Electron,vol.51，No.4，pp.744–757

发表日期：

2004年8月

班级：

姓名：

学号：

指导教师：

翻译日期：

英文原文：

DirectTorqueControlofInductionMotorsUtilizingThree-LevelVoltageSourceInverters

XavierdelToroGarcia,AntoniArias,MarcelG.Jayne,

andPhilA.Witting

Abstract—Anewcontrolstrategyforinductionmotorsbasedondirecttorquecontrolispresentedwhichemploysathree-levelinverterinsteadofthestandardtwo-levelinverter.Thecontrollerisdesignedtoachieveatorqueripplereductionbytakingadvantageoftheincreaseinthenumberofinverterstatesavailableinathree-levelinverter.Theharmonicdistortioninthestatorcurrentsandtheswitchingfrequencyofthesemi-conductordevicesarealsoreducedinthenewcontrolsystempresented.

IndexTerms—Inductionmotordrives,three-levelconverter,torquecontrol.

I.INTRODUCTION

Thestandardvoltagesourceinverter（VSI）traditionallyusedinelectricaldrivesystemsisthetwo-levelVSI,whichunfortunatelyhasanumberofinherentlimitations.Forexample,themaximumvoltagethatcanbesupportedbythesemiconductorswitchingdevicesintheVSIlimitsthemaximumvalueofdc-linkvoltage.Furthermore,theoutputvoltagesandcurrentsfromtheVSIcancontainhighharmonicdistortion.TheoutputvoltagewaveformscanalsocontainlargevaluesofdV/dt,whichcontributetothedegradationofthemachinewindingsinsulationandbearings,andalsoproduceconsiderableelectromag-neticinterferenceduringoperation.NewmultilevelVSItopologies,however,canconsiderablyreducemanyoftheselimitations[1].

Themostcommonlyusedmultileveltopologyisthethree-levelneutralpointclamped（NPC）VSI[2].ThistypeofVSIhasadvantagesoverthestandardtwo-levelVSI,suchasagreaternumberoflevelsintheoutputvoltagewaveforms,lessharmonicdistortion,andlowerswitchingfrequencies.

Directtorquecontrol（DTC）hasemergedtobecomeapossiblealternativetothewell-knownvectorcontrolstrategiesforinductionmotorcontrolsystems[3],[4].Althoughconsiderableresearchhasbeenmadeintothetwo-leveltopologiesassociatedwiththismethodofcontrol,theamountofresearchcarriedouttodateintoDTCsystemsemployingmultileveltopologiesisstillratherlimited.Themajoradvantageofthethree-levelVSItopologywhenappliedtoDTCistheincreaseinthenumberofvoltagevectorsavailable.Thismeansthenumberofpossibilitiesinthevectorselectionprocessisgreatlyincreasedandleadstoamoreaccuratecontrolsystem,whichcanresultinareductionofthetorqueandfluxripples.Thisisofcourseachievedattheexpenseofanincreaseinthecomplexityofthevectorselectionprocess.AlthoughseveralauthorshaverecentlyproposedtheimplementationofDTCutilizingthishigher-leveltopology,theirapproachesarebasedontheuseofmorecomplexvectorselectiontablescombinedwithmodulationtechniquesbasedonanalyticalmethodswhichhavemachineparameterdependency[5][6].Adifferentapproachisaselectiontablebasedontheconceptofvirtualvectors[7].ThesenewmethodsconsiderablyincreasethecomplexityofthecontrolstrategywhencomparedtotheclassicalDTCsystem[3],andtheycannotbeextendedtodifferentmultileveltopologieswithahighernumberoflevelsbecauseofthetableselectionmethodadopted.

Fig.1.Schematicdiagramofthenewcontroller.

ThispaperdescribesacontrollerbasedonDTCthatcanbeappliedtodifferentmultilevelVSItopologies.Itavoidstheuseofhysteresiscomparatorsandlook-uptables,anditdoesnotrequiretheknowledgeofthemotormodelinthecontrolsystemexceptfortheinherentestimatorasintheclassicalDTCsystem.

II.NEWCONTROLLER

ThegeneralstructureofthenewcontrollerisshowninFig.1.Thisnovelcontrollergeneratesareferencestatorvoltagevector（u∗s）inα–βcoordinates（usα,usβ）accordingtotheDTCbasicprinciple,ratherthanusingtheVSIstatelook-uptableasusedinclassicalDTC.ThisapproachadoptedisclosetotheDTCwithspacevectormodulationschemewithclosed-loopfluxandtorquecontrol,andstatorfluxorientedcontrol[4].Morerecently,othersimilarmethodsbasedonthepredictivetorquecontrolconcepthaveappeared[8][9].

Theinputstothecontrollerarethestatorfluxerror（eψs）,thetorqueerror（eΓe）and,additionally,thestatorfluxangularspeed（ωB）,whichisobtainedtoincorporatethebackelectromotiveforce（BEMF）termtoimprovethetorqueresponseatdifferentoperatingpoints.Thereferencevoltagevectorcalculatedbythecontrollercanbesynthesizedusingdifferenttechniqueswithdifferentdegreesofcomplexity,suchaschoosingthenearestvectoravailableorusingmodulationtechniques[9]–[11].ThiscontrollercanbeappliedtoanytopologybecausethetypeofVSIonlyaffectsthewaythereferencevoltagevectorhastobesynthesized.

Thecontrollerisbasedontheprinciplethatthedesireddecoupledcontrolofthestatorfluxmodulusandtorqueisachievedbythecontrolleractingontherespectiveradialandtangentialcomponentsofthestatorfluxvector（ψB）.Thevariationofthestatorfluxvectorisapproximatelyproportionaltothevoltagevectorappliedtothemotor.Therefore,whencalculatingthereferencevoltagevector（inx–ycoordinatesfixedtothestatorfluxvector）,thetangentialcomponent（u∗sy）willdependonthetorqueerror（eΓe）,whereastheradialcomponent（u∗sx）willdependonthestatorfluxerror（eψB）.AscanbeseeninFig.1,twoclosed-loopproportionalcontrollersareemployedtogeneratethecomponentsofthereferencevoltagevector.KψsandKΓearetheproportionalgainsofthesecontrollersandhavebeentunedexperimentallytoachieveaminimumtorqueandfluxripple.TheirinitialvaluescanbesettoapproximatelytheratiobetweennominalstatorvoltageandnominalstatorfluxmodulusforKψs,andtheratiobetweennominalstatorvoltageandnominalstatorflux

Fig.2.TorqueresponsecharacteristicsforclassicalDTCwithatwo-level

VSI.Operatingpoint:

Γ=7.4Nm.ωm=200r/min.

modulusforKψs,andtheratiobetweennominalstatorvoltageandnominaltorqueforKΓe.

ItcanbeseeninFig.1thatafeedforwardactionthatcompensatestheBEMFtermisaddedtotheoutputofthetorquecontrollertocalculatethetangentialcomponentofthereferencevoltagevector.TheBEMFtermisobtainedbymultiplyingthenominalstatorfluxmodulus（ψsn）andthestatorfluxangularspeed（ωs）,whichispreviouslyfilteredbymeansofalow-passfilter.

Thereferencevectorinx–ycoordinatesisthentransformedtoα–βfixedcoordinates.ThenovelcontrollerdevelopedsynthesizesthereferencevoltagebychoosingthenearestVSIvectortothereferencevoltagevector.ThenearestvectorisfoundbymeansofcalculatingtheminimumdistanceofthevoltagevectorsthatcanbedeliveredbytheVSItothereferencevoltagevector.Thiscalculationinvolvesevaluatingthemodulusofthedifferencebetweenvectors.ThecomplexityofthesystempresentedisincreasedwhencomparedtoclassicalDTCduetotheuseofproportionalcontrollersinsteadofhysteresiscomparators,thex–ytoα–βcoordinatetransformationandthemethodtofindthenearestvector.Finally,itshouldbenotedthatthebalanceoftheneutralpointvoltageisoneofthemainissuesassociatedwiththecontrolofthethree-levelNPCVSI[11].InthenovelcontrollerthebalanceisachievedbyselectingtheappropriateconfigurationamongtheredundantpossibilitiesthatexistforsomeofthevectorsdeliveredbytheVSI.

III.EXPERIMENTALRESULTS

ThepracticalimplementationofthenewcontrollerisbasedonadSpaceDS1103boardthatperformsthecontroltasks.ThisboardcontainsaPowerPCandaDSP.Athree-levelNPCVSIutilizingIGBTdevicesisusedtosupplya380/220-Vfour-pole1.1-kWcage-rotorinductionmotor.Thedc-linkvoltageemployedis200V.Figs.2and3showthesteady-statetorqueresponsesat200r/minandnominaltorqueconditions（7.4Nm）fortheclassicalDTCstrategywithatwo-levelVSIandthenewcontrolsystememployingathree-levelVSIdescribedinthispaper,respectively.Thesampletimeusedwas100µsinbothsystems.

Toassesstheperformanceofbothsystems,thetorquestandarddeviation（σΓe）iscalculatedforthetorqueripple.Additionally,thefluxstandarddeviation（σψs）,thetotalharmonicdistortion（THD）ofthestatorcurrentTHD_iS,andthemeanswitchingfrequencyinthesemiconductordevices（FSw）arecalculatedforbothsystems.FromtheexperimentalresultsshowninFigs.2and3,itisapparentthatthetorquerippleforthenewsystemutilizingathree-levelVSIisconsiderablyreduced.Theresult

Fig.3.Torqueresponsecharacteristicsforthenewcontrollerwithathree-levelVSI.Operatingpoint:

Γ=7.4Nm.ωm=200r/min.

oftheVSIswitchesintheproposedsystemarebothreducedbymorethan50%.Theswitchingfrequencyisreducedduetotheutilizationofathree-levelVSI.InthistypeofVSI,sometransitionsbetweenthethreepossiblestatesofalegdonotinvolvethecommutationofalltheswitches.

IV.CONCLUSION

AnewcontrollerbasedontheDTCprincipleispresented,anditisshownthatthecontrollercanbeeasilyimplementedinathree-levelVSIdrivesystem.Thenewcontrollerdoesnotinvolvetheuseofanymotormodelparameters,asinclassicalDTC,andtherefore,thecontrolsystemismorerobustcomparedtoothermethodsthatincorporatemotorparameters.TheexperimentalresultsobtainedforthenewDTCschemeemployingathree-levelVSIillustr