西安文理學院本科畢業(yè)設計（論文）第1頁SoftStartingofInductionMotorWithTorqueControlAdemirNied,Member,IEEE,JosdeOliveira,RafaeldeFariasCampos,RogrioPinhoDias,andLuizCarlosdeSouzaMarquesAbstractThispaperpresentsasimpletechniquebasedonstator-fluxestimationtocontroltheelectromagnetictorqueofin-ductionmotors(IMs)duringsoftstarting.Theinherentproblemsrelatedtopureintegrationofthebackelectromagneticforcetoestimatethestatorfluxareminimizedusingthelow-pass-fllterapproach.Theexperimentalresultsaredealtwithandcomparedwiththeusualcurrent-controltechnique.Theresultsobtainedval-idatetheproposedtechnique,showingitsviabilityinapplicationswheretheobjectiveistofittheIMtorqueprofileduringstartingorstoppingaccordingtotheloadtorque.IndexTermsInductionmotor(IM),softstarter,torquecontrol.I.INTRODUCTIONTHEacmotorstartersemployingpowersemiconductorsarebeingincreasinglyusedtoreplaceelectromagneticlinestartersandconventionalreduced-voltagestartersbecauseoftheircontrolledsoft-startingcapabilitywithlimitedstartingcurrent1.Thyristor-basedsoftstartersarecheap,simple,reliable,andoccupylessvolume,andtherefore,theiruseisaviablesolutiontotheinductionmotor(IM)startingproblem2.Theangle-ramptechniqueisknownasthevoltage-ramptechniquebecauseitdoesnothaveavoltagefeedbackappliedtothemotor.ItmeansthattheIMvoltageiscontrolledthroughafiring-anglerampofthethyristorsinanopenloop.Thistechniqueissimple,anditisusedinlow-costcommercialsoftstarters.Itwillalwaysproduceastartingquadratictorquecurvethatcanbeappliedtosmallhydraulicpumpsandsmallfans.Dependingontheinitialswitchinginstantsofallthethreephasestothesupply,anIMmayproduceseverepulsationsontheelectromechanicaltorque,regardlessofwhetheritiscontrolledbyadirect-onlinestarterorasoftstarter3.Theelectromagnetic-torquepulsationsmaycauseshockstothedrivenequipmentanddamagetomechanicalsystemcomponents,suchasshafts,couplings,andgears,immediatelyPaper2009-IDC-024.R3,presentedattheIndustryApplicationsSocietyAnnualMeeting,Edmonton,AB,Canada,October59,andapprovedforpublicationintheIEEETRANSACTIONSONINDUSTRYAPPLICATIONSbytheIndustrialDrivesCommitteeoftheIEEEIndustryApplicationsSociety.ManuscriptsubmittedforreviewJanuary31,2009andreleasedforpublicationOctober30,2009.FirstpublishedMarch25,2010；currentversionpublishedMay19,2010.ThisworkwassupportedbyWEGEquipamentosEltricos.A.Nied,J.deOliveira,andR.deFariasCamposarewiththeDe-partmentofElectricalEngineering,UniversidadedoEstadodeSantaCatarina,Joinville89223-100,Brazil(e-mail:西安文理學院本科畢業(yè)設計（論文）第2頁dee2anjoinville.udesc.br；dee2jojoinville.udesc.br；.br).R.P.DiasiswithWEGEquipamentosEltricos,JaragudoSul3000,Brazil(e-mail:).L.C.deSouzaMarquesiswiththePowerElectronicsandControlResearchGroup,UniversidadeFederaldeSantaMaria,SantaMaria97105-900,Brazil(e-mail:marques_).DigitalObjectIdentifier10.1109/TIA.2010.2045335ifthestrengthofmaterialsisexceeded,orinthelongterm,owingtofatigue2.Numerousattemptshavebeenmadeontheperformanceanalysisandcontroltechniquesofathree-phaseIMfedfromathyristorizedvoltagecontroller49.In8,adynamicfunctionwasusedforthethyristortriggeringangleinthevoltagecontrollerprovingtobeasimpleandeffectivewaytoimprovetransientperformance.Therateatwhichthemainfiuxbuildsupisdecreased,andthetransienttorqueissmoothedbyemployingapropertriggeringfunction.In1,somecontrolstrategiesareproposedtoeliminateelectromagnetic-torquepulsations,bothatstartingandreclos-ing,andtokeepthelinecurrentnearlyconstantatapresetvalueovertheentirestartingperiod.Theproposedcurrent-controlstrategyiscomposedofsuccessivecosinesandconstantfunctionsegmentsofthyristortriggeringangle.In2,theperformanceoftheIMduringvoltage-controlledsoftstartinghasbeenoptimizedbyeliminatingthesupply-frequencytorquepulsationsusingapulsating-torqueelimina-tionstrategyappliedin10and11,byextendingittocoveralloftheoperatingconditionsofasoftstarter,andbykeepingthelinecurrentconstantatthepresetvalueovertheentiresoft-startingperiod.Thus,in1and2,thetechniqueusedtostarttheIMwithsoftstarterisbasedontheclose-loopcontrolwithcurrentlimitation.Thiscurrent-controltechniquecanprovideaconstanttorqueduringthebeginningandinthemiddleofthestartingprocess.However,duringthefinalperiodofthisprocess,onecanverifytheexistenceofatorquepulse,inwhich,forcertainkindsofloads,anabruptaccelerationcanbegenerated.Therefore,itseemsthatagoodsolutiontosolvethisproblemistodirectlycontroltheelectromagnetictorqueduringthestartingprocess.Inthispaper,atorque-controltechniqueisproposedtoeliminatetheelectromagnetic-torquepulsationsandtokeepthelinecurrentnearlyconstantatapresetvalueovertheentiresoft-startingperiod.ThisstrategyallowsthetorquetobecontrolledinsuchamannerthataconstanttorqueorevenatailoredtorquecanbefollowedbytheIMduringstartingorstoppingprocess.Theproposedtechnique,besidesmakingthebenefitsobtainedfromthecurrent-controltechniquepreviouslycitedpossible,alsoallowscancelingthetorquepulseandtheaccel-erationverifiedattheendoftheIMstarting.Thecontrol,protection,andmonitoringfunctionsoftheproposedtechniqueareimplementedinamicrocontroller.The-oreticalresultsareverifledexperimentallyusingacustom-designedexperimental西安文理學院本科畢業(yè)設計（論文）第3頁setup.Thispaperisorganizedasfollows.SectionIIdescribestheproposedtorque-controltechniqueandoperationprinciples；NIEDetal.:SOFTSTARTINGOFINDUCTIONMOTORWITHTORQUECONTROLFig.1.Proposedcontroltechniqueschematicdiagram.Fig.2.Proposedcontroltechniquedetaileddiagram.SectionIIIshowstheapproachusedtoestimatethefluxfromwhichtheelectromagnetictorquewillbeobtained；SectionIVpresentsexperimentalresultsoftheproposedtechnique,andfinally,conclusionsaregiveninSectionV.II.SYSTEMDESCRIPTIONANDOPERATIONPRINCIPLESTheschematicdiagramoftheIMsoftstarterwiththepro-posedtorque-controltechniqueisgiveninFig.1.Theelectromagnetic-torqueestimationisobtainedusingalow-passfilter(LPF)asthestator-fluxestimatorwhichelim-inatestheanaloginputoffset.Theclosed-looptorquecontrolallowsthe西安文理學院本科畢業(yè)設計（論文）第4頁productionofthedesiredstart-torqueprofilefromtheadoptedreferencetorque(TREF),adjustingtheelectromagnetictorque(Tem)totheloadtorque.Fig.2showsadetaileddiagramoftheIMsoftstarterwiththeproposedtorque-controltechnique.Thisdi