传感器SRM驱动器中英文对照外文翻译文献.docx
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传感器SRM驱动器中英文对照外文翻译文献
中英文对照翻译
(文档含英文原文和中文翻译)
ASimpleExcitationPositionDetectionMethodforSensorlessSRMDrive
Acknowledgements
TheresearchforthispaperwasperformedinDr.G.Schröder’slaboratoryduringMr.Kim’s2006summerinternprogramofSiegenUniversity,Germany.TheauthorsthankKRF(KoreaResearchFoundation)forsupportingtheprogram.
Keywords
«SwitchedReluctanceDrive»,«SensorlessControl»
Abstract
ThispaperdescribesasimplifiednovelsensorlesscontrolofanSRMbydetectingacurrentlevelduringthenon-excitationperiod.Sincetheinductanceofthemotorisafunctionoftherotorposition,asimpledetectingcurrentpulsecausedbyaregulatedpulsevoltagegivesinformationontherotorposition.Inthispaper,asmalldetectingpulsecurrentiscomparedtothepresetcurrentlevelswhichareproportionaltoturn-onandturn-offpositions.Andthecomparisonresultsareusedfortheexcitationofthenextphase.Thesuggestedmethodisverifiedbysomesimulationsandexperimentaltests.
Introduction
Aswitchedreluctancemotor(hereinafterreferredtoasan“SRM”)isapowerdrivedevicewhichcanbeeasilyandinexpensivelymanufactured,andithasrelativelyhighreliabilitysinceitisproofagainstcertaindrivefaults.Hence,anSRMdrivesystemhassomecharacteristicscomparablewithanexistinginductionmotorinviewofhightorque,ahighoutputdensity,ahigh-efficientvariablespeeddrive,andaneconomicpowerinverterinapplicationfieldssuchasindustrialmachinery,airplanes,automobiles,consumerdevices,andothers[1-2].
InthecontrolofanSRM,onaccurateinformationofrotorpositionisessentialforcorrectphasewindingexcitation.Sincetheoutputtorqueisdependentontheexcitationperiodandexcitedphasecurrent,theaccuracyoftherotorpositionisveryimportant.Inageneralspeedcontrolsystem,anopticalencoderiswidelyusedfordetectingoftherotorposition.Recently,sensorlesscontrolandpositiondetectingtechniquesareinterestinginpracticalapplicationsduetoproblemsofopticalencoderinharshenvironmentandcost.
Inordertogetasensorlessrotorposition,mathematicalbasedobserversandfluxdetectingmethodsareused[3-6].Sincetheaccuracyoftheestimatedrotorpositionofanobserverisdependentonthe
mathematicalmodelandelectricalparameters,theestimationerrorislargeinthelowspeedrange.Anditisverydifficulttogettherotorpositioninstandstill.Althoughthefluxdetectingmethodcaneasilyestimatetherotorpositionwithoutanycomplexmathematicalmodel,alook-uptableoffluxandrotorpositionisrequired.Andtherelationshipoffluxandrotorpositionhasnon-linearcharacteristicduetothesaturationeffect.Recently,fuzzylogicandANN(ArtificialNeuralNetworks)havebeenusedinspeedestimation[7-8]
Thispaperpresentsasimplifiednovelapproachofsensorlesscontrolwithoutacomplexcalculationoftherotorpositionfromtheestimatedinductance.Sincetheoutputtorqueisdependentonexcitationpositionandexcitedcurrent,theproposedsensorlessschemedeterminestheexcitationpatternonlyfromthedetectingcurrentinanon-excitedphasewindingduringthedetectingperiod.Theturn-onandturn-offpositionsaredeterminedbythedetectingphasecurrentlevelsthatareinverse-proportionaltorotorpositioninthedetectingperiodofthepreviouslyexcitedphase.Inordertogetalinearrelationshipbetweenrotorpositionanddetectedphasecurrent,ashorttestvoltageisappliedduringthedetectingperiod.Sincetheproposedsensorlessschemedoesnotuseacomplexinductancecalculation,theexcitationpatterncanbeeasilydeterminedbyasimplecomparator.Thesuggested
methodisverifiedbysomesimulationsandexperimentaltests.
TheGeneralPrinciplesofSRM
Fig.1showsanSRdrivesystemanditstorquecharacteristics.IntheFig.1,theoutputtorqueisproducedintheinductancevariationregionshowninFig.1(b).
(a)SRdrivesystem
(b)Torquecharacteristicswithconstantcurrent
Fig.1:
SRdrivesystemandtorquecharacteristics
Theoutputtorquecanbeexplainedbytherelationshipofcurrentandinductanceasfollows.
Inordertoestimatethephaseinductance,thephasecurrentexcitedbyaswitchingtestpulsevoltageisusedateverysamplingperiodshownasFig.2.
Fig.2:
Waveformoftestpulsevoltageandphasecurrentforinductanceestimation
Thevoltageequationforestimatingthephaseinductancecanbederiveddisregardingthevoltage
dropofthephaseresistanceandtheback-emf.From
(2),thephaseinductancethatisafunctionofthe
rotorpositioniscalculated,andtherotorpositionisestimatedfromthecalculatedinductance
accordingto(3).Inspiteofacomplexcalculation,theestimatedrotorpositionfromthecalculated
inductancehassomeerrorduetothesaturationeffectincludingthenon-linearcharacteristicsofthe
inductanceandthevoltagedropofthephaseresistance.
TheProposedSensorlessControlSchemeofSRM
SwitchingPatternDetermination
Fig.3:
Theproposeddetectingschemeofsensorlessexcitation
Fig.3showstheproposeddetectingalgorithmofthesensorlessexcitationofthe3-phaseSRM.Differentlyfromageneralexcitationmethod,theproposedschemehasexcitation,detectingandnonexcitationperiodsineachphase.
Intheexcitationperiodwhichisdeterminedbytheothersnon-excitedphases,excitedphasecurrentproducesoutputtorque.Andtheappliedvoltageofeachphasewindingintheexcitationperiodiscontrolledbythespeedcontrollerandexcitationcurrentcontroller.Theamplifieddetectedcurrentinthedetectingperiod,iscomparedtopresetturn-onandturn-offcurrents,IonandIoffwhicharedeterminedbyposition-currentcharacteristicoftheproto-typeSRM.Thecomparisonresultofferstheotherphase’sturn-onandturn-offpositionθonandθoff,respectively.Inthenon-excitationperiod,thephasecurrentdoesnotflowthroughthephasewinding.Inthedetectingperiod,theamplifieddetectedcurrenthasnearlylinearslopeduetothedecreasingphaseinductance.Sincethewidthofthetestpulsevoltageisverynarrowandthedetectedcurrentisverysmall,saturationeffectofphase
inductancecanbeignored.Sotheslopeofthedetectingcurrentislinearaccordingtorotorpositionineachphasewindings.Butthedetectingperiodofanun-excitedphaseislocatedinthenegativetorqueregionshownasFig.2.SincethedetectingphasecurrentproducesnegativetorqueandDC-linkvoltagecanbechanged,testpulsevoltageshouldbelimitedandcontrolledforthestableoperation.Inordertolimitthenegativetorqueproducedfromdetectingcurrent,thedurationoftestpulsevoltageiscontrolledaccordingtoDC-linkvoltageinthispaper.ThemaximumdetectingphasecurrentisproducedintheminimuminductancerangeandthedetectingperiodofvoltagepulsecanbederivedasfollowswithnegativetorquelimitTNLMT.Inthispaper,thenegativetorquelimitTNLMTisdeterminedas2%ofratedtorqueofSRM,andthemaximumperiodoftestpulseislimitedto20[us].
where,θmaxandθminaretherotorpositionofmaximuminductance,Lmaxandminimuminductance,Lmin,respectively.
Fig.4showsthedetailedblockdiagramofthesensorlessswitchingpositiondetectingmethod.Theproposedturn-onandturn-offpositionestimatorconsistsofthepositionlevelgeneratorandthecurrentlevelcomparator.Thepositionlevelgeneratorproducesturn-onandturn-offcurrentlevelsfrompre-calculatedlook-uptable.
Fig.4:
Theblockdiagramoftheproposedsensorlessswitchingpositiondetection
Thecontentofthelook-uptableissimplymeasuredwithafixedtestvoltagepulseaccordingtorotorposition.Becausethetestvoltagepulseisshortduetothelimitationofnegativetorqueproduction,theoutputcurrentlevelsareapproximatelyinverseproportionaltotheinductance.Ifthesensorlesscontrolsystemusesafixedturn-onandturn-offposition,thelook-uptablecanbeomitted.Sincethedetectingpulsecurrentisverysmallduetothelimitationofnegativetorque,itisamplifiedandlimitedabyzenerdiode.Thereferenceturn-onandturn-offposition,θ*on,θ*offchangewithIonandIofffromtheposition-currentlook-uptable.Thelook-uptableissimplepre-measuredwithtestpulses.Andthepresetturn-onandturn-offpositioncurrentarecomparedtotheamplifieddetectingcurrent.Thetriggerpulsesaregeneratedwhenthedetectingcurrentislargertheneachpresetvalue.ThetriggerpulsesareinputasinterruptsoftheDSP,andestimatedturn-on,turn-offpositionare
determined.Therotorspeedissimplyestimatedbytheestimatedturn-onandturn-offpositionofeachphase.
TheExcitationPhaseandPositionatStandstill
Inthestandstill,thefirstswitchingpatternisdeterminedfromdetectingcurrentexplainedintheFig.4.Itshowstherelationshipbetweendetectingcurrentandeachpossiblepositionatstandstill.Intheidealcase,pointa0,b0andc0whichthemaximumperiodofeachdetectingcurrentarethecriticalboundaryforthefirstexcitationphase.
Fig.5:
Thedetectingcurrentsofeachphaseaccordingtothestandstillposition
TheExperimentalResults
Inordertoverifytheproposedsensorlessscheme,a12/8SRMandaDSPcontrollerwith
asymmetricconverterareused.Table1showsthespecificationsofthe12/8SRMundertest.ThemaincontrollerisimplementedbyaTMS320F2812fromTexasInstrumentsanda600V/25AasymmetricconvertermoduleSK25GAD063TfromSEMIKRON.
Fig.6:
Theexperimentset-up
TheproposedsensorlessPIcontrollerisimplementedinaTMS320F2812.Anencoderisusedforpositionmonitoring.TheasymmetricconverterislocatedundertheDS