On the Properties of Full-Order Observers for Sensorless Induction Motor Drives

全阶磁链观测器

OnthePropertiesofFull-OrderObserversforSensorless

InductionMotorDrives

LennartHarneforsABBPowerSystemsSE-77180Ludvika,Sweden

E-mail:lennart.harnefors@http://doc.xuehai.net

MarkoHinkkanen

PowerElectronicsLaboratory,HelsinkiUniversityofTechnology

FI-02015TKKEspoo,FinlandE-mail:marko.hinkkanen@tkk.

Keywords

Electricaldrive,Estimationtechnique,Inductionmotor,Sensorlesscontrol

Abstract

Itisshownthatafull-orderobserverforcurrent, ux,andspeedestimationofsensorlessinductionmotordrives,undertheassumptionoffastcurrentdynamics,hasanequivalentimplementationsasareduced-orderobserverfor uxandspeedestimationonly.Thisreduced-orderobserverisanalyzed.Allgainselectionswhichgivestabilityforalloperatingconditions,includingtheregenerationmode(calledcompletestability),arefound.Consequently,allgainselectionsofthefull-orderobservergainsforwhichcompletestabilityisobtained,undertheassumptionstated,arealsofound.Thisallowsthestabilitypropertiesofanycandidatefull-orderobservergainselectiontobeevaluated.

Introduction

Mostestimatorsproposedforcombined uxandspeedestimationinsensorlessinductionmotor(IM)drivescanbeclassi edinthreecategories:

Model-referenceadaptivesystems(MRASs)[1],inwhichtheoutputsoftwo uxestimators—oftenthe“currentmodel”(CM)andthe“voltagemodel”(VM)—arecompared,andthedifferenceisusedtoadjusttherotor-speedestimatetoitscorrectvalue. Full-orderobservers[2],whichproduceestimatesofboththestatorcurrentandthestatororrotor ux.Correctionismadebytheerrorbetweenthemeasuredstatorcurrentanditsestimate,whichisalsousedtoadjustthespeedestimateinanadaptationlaw. Reduced-orderobservers[3],whichareestimatorsonlyofthestatororrotor ux.Reduced-orderobserverscanbemadeinherentlysensorless[4],i.e.,http://doc.xuehai.netbined uxandspeedestimationisbynomeansstraightforward.Challengesincludegaininggooddampingatallspeeds,lowparametersensitivity,lownoisegain,and—mostimportantly—stabilityforalloperatingconditions,apropertyherecalledcompletestability.

Duringrecentyears,workscomparingandbuildingbridgesbetweentheschemeshaveappeared.In[5],itisshownthat,ifthestatorandrotor uxesarechosenasstatevariablesinafull-orderobserver,thebasicMRASestimatorisobtainedasaspecialcase.TwoMRASvariantsandafull-orderobserverarecomparedin[6],while[7]presentsacomparisonbetweenfull-orderobserversandinherentlysensorlessestimators.Relationsbetweenfull-orderobservers,reduced-orderobservers,andMRASsarepresentedin[8].

Furthermore,anumberofworksproposingpartialorcompletesolutionstotheseriousproblemofregeneration-modeinstability[9]haveappeared,mostsince2000[8],[10]–[21].Completelystableschemes,i.e.,devoidofanunstableregion,arenaturallyhighlydesirable.Yet,manyschemes,e.g.,

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