基于MATLABSimulink的异步电机仿真.docx

基于MATLABSimulink的异步电机仿真.docx

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基于MATLABSimulink的异步电机仿真

InductionMotorTestsUsingMATLAB/SimulinkandTheirIntegrationIntoUndergraduateElectricMachineryCourses

Abstract—ThispaperdescribesMATLAB/Simulinkimplementationofthreeinductionmotortests,namelydc,no-load,ndblocked-rotortestsperformedtoidentifyequivalentcircuit

parameters.Thesesimulationmodelsaredevelopedtosupportndenhanceelectricmachineryeducationattheundergraduateevel.TheproposedtestshavebeensuccessfullyintegratedintolectricmachinerycoursesatDrexelUniversity,Philadelphia,PA,andNigdeUniversity,Nigde.Turkey.IndexTerms—Education,inductionmotors,MATLAB/Simulink,softwarelaboratory.

I.INTRODUCTION

WITHTHEadventoflow-costpersonalcomputersandvariouseasilyaccessiblesoftwarepackages,computer-aidedteachingtoolshavebecomeanessentialpartofbothclassroomlecturesandlaboratoryexperimentsinelectricalmachineryeducation[1]–[6].Thecomputermodelsandsimulationsofinductionmotors,asteachingtools,supporttheclassroomteachingbyenablingtheinstructor,throughthecomputer-generatedgraphics,toillustrateeasilysteady-stateoperationofthemotorundervariousloadingconditions.

Forpersonaluseonlyinstudyandresearch;notforcommercialuse

Thecomputationaltoolsasapartoflaboratoryexperimentsenhancelaboratoryexperiencebyprovidingstudentswiththeopportunitytoverifytheresultsoflaboratoryexperimentsandcomparethemwiththoseobtainedbycomputersimulations.Suchacomparisonopportunityhelpsstudentsrealizethelimitationsofhardwareexperimentsand,asacounterpoint,appreciatethatcomputermodelscannotsubstituteforactualhardwareexperimentsthatmightnotexactlyrepresenttheoperationofinductionmotorsbecauseofsomemodelingassumptions.Moreover,anundergraduateelectricmachinerycoursethatintegratesup-to-datecomputerhardwareandsoftwaretoolsinbothlectureandlaboratorysectionsalsomeetstheexpectations

oftoday’sstudentswhowanttousecomputersandsimulationtoolsineveryaspectsofacourse,andthus,possiblyattractsmorestudents.

Electricalmachinerycoursesattheundergraduateleveltypicallyconsistofclassroomandlaboratorysections.Theclassroomsectioncoversthesteady-stateoperationoftheinductionmotorinwhichtheper-phaseequivalentcircuitisusedtocomputevariousmotorquantities,suchasinputcurrentandpower,powerfactor,developedtorque,andefflciency.Thecomputationsassociatedwiththesteady-stateoperationrequiretheknowledgeofequivalentcircuitparameters.Theseparametersareobtainedbyperformingthreetests,namelydc,no-load,and

Forpersonaluseonlyinstudyandresearch;notforcommercialuse

blocked-rotortestsonthemotorinatypicallaboratoryexperiment.

Thelaboratorysectionincludesthesetestsandaloadexpermentthatallowsstudentstobecomefamiliarwiththeinducionmotoroperationandtogaininvaluablehardwareandmeasurementexperiences.Theauthors’experiencewhileteachingnductionmotorsatDrexelUniversity,Philadelphia,PA,indicatesthatstudentsgenerallyhavedifflcultywhentheycometohelaboratorytocarryouttheseexperimentseventhoughthecorrespondingtheoryisextensivelycoveredintheclassroomsectionwithadetailedhand-outdescribinglaboratoryfacilitiesandtheprocedureoftheexperiments,giventothematleastaweekbeforethelaboratory.Studentsarenotfamiliarwithalaboratoryenvironmentthatcontainslargemachinesandrelativelycomplexmeasurementmethodsanddevicesascomparedwithotherlaboratoriestheyhavebeentobefore.Thetimeconstraintsduringthelaboratoryexercisearealsoadifflcultadjustment.Inausualtwo-hourlaboratorysection,studentsarerequiredtosetupandperformfourinductionmotorexperiments,totakethenecessarymeasurements,andtoinvestigatesteady-stateperformanceofthemotorundervariousloadingconditions.Becauseofthetimelimitations,studentsoftenrushthroughtheexperimentsinordertoflnishthemontime,whichunfortunatelypreventsthemfromgettingatruefeelingofmotoroperationandromappreciatingwhathasbeenaccomplishedduringthelaboratorypractice.

Therefore,simulationtoolsmustbedevelopedforinductionmotorexperimentstoserveasusefulpreparatoryexercisesbeforestudentscometothelaboratory.Theobjectiveofthispaperistopresentsimulationmodelsoftheseinductionmotorexperimentsinanefforttodesignacomputationallaboratory.Thedc,no-load,andblocked-rotorsimulationmodelsaredevelopedasstand-aloneapplicationsusingMATLAB/SimulinkandPowerSystemBlockset（PSB）.Fortheloadexperiment,studentsarerequiredtowriteacomputerprogramusingMATLAB’sM-flleprogrammingfortheper-phaseequivalentcircuitoftheinductionmotortocomputeoperatingquantities.Suchanassignmentimprovesstudents’programmingskillsthatwouldbehelpfulinotherclassesaswell.

Theremainderofthepaperisorganizedasfollows.SectionIIdescribesthedc,no-load,andblocked-rotortests.Forthesakeofcompleteness,firsttheexperimentalsetupforeachtestisprovidedwithabriefexplanationofhowthesetestsareconductedandhowthecorrespondingmeasurementsareusedtocomputetheequivalentcircuitparameters.Then,foreachtest,thecorrespondingSimulink/PSBmodelispresentedandcomparedwiththeactualexperimentalsetupemphasizingthesimilaritiesanddiscrepancies.SectionIIIcomparestheequivalentcircuitparametersdeterminedusingsimulationdataanddataobtainedfromexperiments.SectionIVexplainshowtointegratethesesimulationmodelsintoundergraduateelectricmachinecoursesattwodifferentuniversities,whilethelastsectionconcludesthepaper.

II.INDUCTIONMOTORTESTS:

EXPERIMENTALSETUPSANDSIMULINK/PSBMODELS

Thesteady-stateoperatingcharacteristicsofathree-phaseinductionmotorareofteninvestigatedusingaperphaseequivalentcircuitasshowninFlg.Inthiscircuit,R1andX1representstatorresistanceandleakagereactance,respectively;R2andX2denotetherotorresistanceandleakagereactancereferredtothestator,respectively;RCresistancestandsforcorelosses;XMrepresentsmagnetizingreactance;andSdenotestheslip.Theequivalentcircuitisusedtofacilitatethecomputationofvariousoperatingquantities,suchasstatorcurrent,inputpower,losses,inducedtorque,andefficiency.Whenpoweraspectsoftheoperationneedtobeemphasized,theshuntresistance（Rc）isusuallyneglected;thecorelossescanbeincludedinefflciencycalculationsalongwiththefriction,windage,andstraylosses.Theparametersoftheequivalentcircuitcanbeobtainedfromthedc,no-load,andblocked-rotortests.Inthefollowing,bothexperimentalsetupandSimulink/PSBmodelsofeachtestaredescribed

ThePSBisausefulsoftwarepackagetodevelopsimulationmodelsforpowersystemapplicationsintheMATLAB/Simulinkenvironment.Withitsgraphicaluserinterfaceandextensivelibrary,itprovidespowerengineersandresearcherswithamodernandinteractivedesigntoolto

buildsimulationmodelsrapidlyandeasily.MATLABandSimulink/PSBhavebeenwidelyusedbyeducatorstoenhanceteachingoftransientandsteady-statecharacteristicsofinductionmachines.Ofcourse,othercommercialsoftwarepackages,suchasMapleandMathCad,arecommonlyusedinelectricalengineeringeducationwiththeiradvantagesanddisadvantages[12].ThereasonthatMATLABwithitstoolboxeswasselectedisthatitisthemainsoftwarepackageusedinalmostallundergraduatecoursesintheauthors’institutionsasacomputationtooltoreinforceelectricalengineeringeducation.Therefore,studentscaneasilyaccesstoMATLAB,andtheyalreadyhavethebasicprogrammingskillstousethegivenSimulinkmodelsandtowritecomputerprogramswhenrequiredbeforecomingtothemachineryclass.

Thedctestisperformedtocomputethestatorwindingresisance.Adcvoltageisappliedtothestatorwindingsofaninductionmotor.Theresultingcurrentflowingthroughthestatorwindingsisadccurrent;thus,novoltageisinducedintherotorcircuit,andthemotorreactanceiszero.Thestatorresistanceisheonlycircuitparameterlimitingcurrentflow.Fig.2showstheexperimentalsetupofthedctestconductedattheInterconnectedPowerSystemsLaboratory（IPSL）[13]ofDrexelUniversity.A120-Vdcpowersourceisappliedtothetwophases

ofaY-connectedinductionmotor.Agroupoflightbulbsarenstalledinthecircuitasaresistiveloadinordertoadjustdccurrenttotheratedvalue.ThecurrentinthestatorwindingsIdlandvoltageacrossthetwophasesofthemotorVdcaremeasured.

DepictstheSimulink/PSBimplementationofthedctest.FromthePSBmachinelibrary,aninductionmotorblockisusedwhoseelectricalparameters（suchasnominalvoltageandequivalentcircuitparameters）andmechanicalparameters（suchasinertiaandnumberofpoles）canbespecifledineitherInternationalSystemofUnits（S.I.）orinperunit.Similartotheexperimentalsetup,a120-Vdcsourceisappliedtothetwophases（phasesAandB）oftheinductionmotorthroughaseriesresistance,whilethephaseCisgroundedthrougharesistancebranchinordertohaveacompleteelectricalconnection.Thepurposeoftheseriesresistancebetweenthedcsourceandtheinductionmotoristolimitthecurrentflowingthroughthetwowindingsofthemotortoitsratedvalue,whichissimilartothelightingbulbsusedinthehardwaresetupofFig.2Voltageandcurrentmeasurementblocksmeasuretheinstantaneousvoltageacrosstwophasesandthecurrentflowingthroughthewindings,respectively.Twoscopesdisplaythewaveformofthevoltageandcurrent,whiletwodisplayboxes