Introduction
Steppermotorisalsocalledpulsemotor,basedonthemostbasicprincipleofelectromagnet,itisakindofelectromagnetthatcanrotatefreely,Itsoperatingprincipleistorelyonthechangeofairgappermeabilitytogenerateelectromagnetictorque.Theoriginalmodeloriginatedbetween1830and1860.Around1870,anattemptwasmadeforthepurposeofcontrol,anditwasappliedtotheelectrodeconveyingmechanismofthehydrogenarclamp.Thisisconsideredtheoriginalsteppermotor.Intheearlytwentiethcentury,steppingmotorswerewidelyusedinautomatictelephoneexchanges.AsWesterncapitalistpowerscompetedforcolonies,steppermotorshavebeenwidelyusedinindependentsystemssuchasshipsandairplanesthatlackACpower.Theinventionofthetransistorinthelate1950swasgraduallyappliedtosteppermotors,makingdigitalcontroleasier.Afterthe1980s,ascheapmicrocomputersappearedinamulti-functionalposture,thecontrolmethodsofsteppingmotorsbecamemoreflexibleanddiverse.
Thebiggestdifferencebetweenasteppermotorandothercontrolmotorsisthatitreceivesadigitalcontrolsignal(electricpulsesignal)andconvertsitintoacorrespondingangulardisplacementorlineardisplacement.ItisitselfacompleteTheexecutiveelementofdigitalmodeconversion.Anditcanbeopen-looppositioncontrol,inputapulsesignaltogetaprescribedpositionincrement,suchaso-calledincrementalpositioncontrolsystemcomparedwiththetraditionalDCcontrolsystem,itscostissignificantlyreduced,almostnosystemadjustment.Theangulardisplacementofthesteppermotorisstrictlyproportionaltothenumberofinputpulses,anditissynchronizedwiththepulseintime.Therefore,aslongasthenumberofpulses,frequencyandphasesequenceofthemotorwindingsarecontrolled,therequiredrotationangle,speedanddirectioncanbeobtained.
mycountry'ssteppermotorsstartedintheearly1970s.Themid-70stothemid-1980swerethefinishedproductdevelopmentstage.Newvarietiesandhigh-performancemotorswerecontinuouslydeveloped.Atpresent,withThedevelopmentofscienceandtechnology,especiallythedevelopmentofpermanentmagnetmaterials,semiconductortechnology,andcomputertechnology,hasenabledsteppermotorstobewidelyusedinmanyfields.
Overviewofsteppermotorcontroltechnologyanddevelopment
Asaspecialmotorforcontrol,steppermotorscannotbedirectlyconnectedtoDCorACpowersourcestowork,andmustusespecialdriversPowersupply(steppermotordriver).Beforethedevelopmentofmicroelectronicstechnology,especiallycomputertechnology,thecontroller(pulsesignalgenerator)wascompletelyrealizedbyhardware,andthecontrolsystemusedseparatecomponentsorintegratedcircuitstoformacontrolloop.Notonlywasthedebuggingandinstallationcomplicated,itconsumedalotofcomponents,andonceAfterfinalizing,thecircuitmustberedesignedtochangethecontrolscheme.Thismakesitnecessarytodevelopdifferentdriversfordifferentmotors.Thedevelopmentdifficultyanddevelopmentcostareveryhigh,andthecontrolisdifficult,whichlimitsthepromotionofsteppermotors.
&Withthedevelopmentofcomputertechnology,thecontrolmethodofthecombinationofsoftwareandhardwarehasbecomethemainstream,thatis,thecontrolpulseisgeneratedthroughtheprogramtodrivethehardwarecircuit.Thesingle-chipmicrocomputercontrolsthesteppermotorthroughsoftware,whichbettertapsthepotentialofthemotor.Therefore,ithasbecomeaninevitabletrendtocontrolsteppermotorswithsingle-chipmicrocomputers,anditisalsoinlinewiththedigitaltrendofthetimes.Mainclassification
Steppermotorshavemanystructuralformsandclassificationmethods.Generally,theyaredividedintothreetypes:reluctancetype,permanentmagnettypeandhybridmagnettypeaccordingtotheexcitationmethod;Numberscanbedividedintosingle-phase,two-phase,three-phaseandmultipleequalforms.
Reactivesteppermotorsarethemainsteppermotorsusedinourcountry.Theoperationperformanceofsteppingmotoriscloselyrelatedtothecontrolmode.Fromthepointofviewofitscontrolmode,thesteppingmotorcontrolsystemcanbedividedintothefollowingthreecategories:open-loopcontrolsystem,closed-loopcontrolsystem,andsemi-closed-loopcontrolsystem.Semi-closed-loopcontrolsystemsaregenerallyclassifiedasopen-looporclosed-loopsystemsinpracticalapplications.
Mainstructure
Thestructurediagramofthethree-phasereluctancesteppingmotormodelisshownintheoverviewdiagram.Itsstatorandrotorcoresaremadeoflaminatedsiliconsteelsheets.Therearesixmagneticpolesonthestator,eachtwooppositemagneticpolesarewoundwiththesamephasewinding,andthethree-phasewindingsareconnectedinastarshapeasthecontrolwinding;therearenowindingsontherotorcore,onlyfourteeth,andthetoothwidthisequaltothestatorpoleshoewidth.
Steppermotoraccelerationanddecelerationprocesscontroltechnology
Becauseofthewideapplicationofsteppermotors,therearemoreandmoreresearchesonthecontrolofsteppermotors.WhenstartingoracceleratingIfthesteppulsechangestoofast,therotorwillnotfollowthechangeofthepower-onsignalduetoinertia,resultinginlockedrotororoutofstep.Overstepmayoccurduetothesamereasonwhenstoppingordecelerating.Inordertopreventstalling,lossofstepandoverstepping,andtoincreasetheworkingfrequency,thesteppingmotormustbecontrolledinspeedupanddown.
Thespeedofasteppermotordependsonthepulsefrequency,thenumberofrotorteethandthenumberofbeats.Itsangularvelocityisproportionaltothepulsefrequency,anditissynchronizedwiththepulseintime.Therefore,whenthenumberofteethoftherotorandthenumberofrunningbeatsareconstant,therequiredspeedcanbeobtainedaslongasthepulsefrequencyiscontrolled.Sincethesteppermotorisstartedbyitssynchronoustorque,thestartingfrequencyisnothighinordernottolosestep.Especiallywiththeincreaseofpower,thediameteroftherotorincreasesandtheinertiaincreases,thestartingfrequencyandthemaximumoperatingfrequencymaydifferbyasmuchastentimes.
Thestartingfrequencycharacteristicofthesteppermotorpreventsthesteppermotorfromdirectlyreachingtheoperatingfrequencywhenitstarts.Instead,theremustbeastartingprocess,thatis,graduallyincreasingfromalowspeedtotheoperatingspeed.Whenstopping,theoperatingfrequencycannotbereducedtozeroimmediately,butaprocessofgradualreductiontozeroatahighspeedisrequired.
Theoutputtorqueofthesteppermotordecreaseswiththeincreaseofthepulsefrequency.Thehigherthestartingfrequency,thesmallerthestartingtorqueandtheworsetheabilitytodrivetheload.Itwillcauselossofstepwhenstarting,andwhenstoppingOvershootwilloccuragain.Tomakethesteppermotorreachtherequiredspeedquicklywithoutlosingsteporovershoot,thekeyistomakethetorquerequiredbytheaccelerationduringtheaccelerationprocessnotonlymakefulluseofthetorqueprovidedbythesteppermotorateachoperatingfrequency,butalsoThismomentcannotbeexceeded.Therefore,theoperationofasteppermotorgenerallyhastogothroughthreestagesofacceleration,uniformspeed,anddeceleration.Itisrequiredthattheaccelerationanddecelerationprocesstimebeasshortaspossibleandtheconstantspeedtimeaslongaspossible.Especiallyintheworkthatrequiresfastresponse,therunningtimefromthestartingpointtotheendistheshortest,whichrequirestheshortestaccelerationanddecelerationprocess,andthehighestspeedatconstantspeed.
Scientificandtechnicalworkersathomeandabroadhaveconductedalotofresearchonthespeedcontroltechnologyofsteppermotors,andestablishedavarietyofaccelerationanddecelerationcontrolmathematicalmodels,suchasexponentialmodels,linearmodels,etc.,andbasedonthisAvarietyofcontrolcircuitshavebeendesignedanddevelopedtoimprovethemotioncharacteristicsofthesteppermotor,andpromotetheapplicationrangeofthesteppermotor.Exponentialaccelerationanddecelerationtakeintoaccounttheinherenttorque-frequencycharacteristicsofthesteppermotor,whichcanensurethatthesteppermotorisnotlostduringmovement.Inaddition,theinherentcharacteristicsofthemotorarefullyutilized,andtheaccelerationanddecelerationtimeisshortened.However,itisdifficulttoachievelinearaccelerationanddecelerationduetochangesinthemotorload.Thecharacteristicsofthefluctuationofthepowersupplyvoltageandtheloadenvironment.Theaccelerationofthisspeed-upmethodisconstant.Itsdisadvantageisthatthecharacteristicsoftheoutputtorqueofthesteppingmotorchangingwiththespeedarenotfullyconsidered,andthesteppingmotorwilllosestepathighspeed..
Subdivisiondrivecontrolofsteppingmotor
Duetothelimitationofitsownmanufacturingprocess,thesteppingangleisdeterminedbythenumberofrotorteethandthenumberofrunningbeats,buttherotorThenumberofteethandthenumberofrunningbeatsarelimited,sothestepangleofsteppingmotorsisgenerallylargeandfixed.Thesteppingresolutionislow,lacksflexibility,vibratesatlowfrequencies,andthenoiseishigherthanothermicromotors.Thephysicaldeviceispronetofatigueordamage.Theseshortcomingsmakethesteppermotorcanonlybeusedinsomeoccasionswithlowerrequirements.Fortheoccasionswithhigherrequirements,closed-loopcontrolcanonlybeadopted,whichincreasesthecomplexityofthesystem.Theseshortcomingsseverelylimitthesteppermotorasanexcellentopen-loopEffectiveuseofcontrolcomponents.Thesubdivisiondrivetechnologyeffectivelyovercomestheseshortcomingstoacertainextent.
Steppermotorsubdivisiondrivetechnologyisadrivetechnologydevelopedinthemiddleofthedecadethatcansignificantlyimprovethecomprehensiveperformanceofsteppermotors.In1988,AmericanscholarsfirstproposedthestepanglesubdivisioncontrolmethodofsteppingmotorattheannualmeetingofincrementalmotioncontrolsystemanddeviceintheUnitedStates.Inthefollowingtwentyyears,thesteppermotorsubdivisiondrivehasbeengreatlydeveloped.Graduallydevelopedtofullmaturityinthe1990s.Theresearchonsubdivisiondrivingtechnologyinmycountryhasthesamestartingtimeasthatinforeigncountries.
Inthemid-nineties,ithasachievedgreatdevelopment.Itismainlyusedinindustries,aerospace,robotics,precisionmeasurementandotherfields,suchasphotoelectrictheodolitesfortrackingsatellites,militaryinstruments,communicationsandradars.Thewideapplicationofsubdivisiondrivetechnologymakesthenumberofphasesofthemotornotlimitedbythestepangle.,Bringsconveniencetoproductdesign.Atpresent,inthesubdivisiondrivetechnologyofsteppermotors,theuseofchoppingconstantcurrentdrive,instrumentpulsewidthmodulationdrive,currentvectorconstantamplitudeanduniformrotationdrivecontrolstop,greatlyimprovetheoperationaccuracyofthesteppermotor,sothatthesteppermotorisinthemiddle,Thefieldoflow-powerapplicationsisdevelopinginthedirectionofhighspeedandprecision.
Controlstrategy
PIDcontrol
Asasimpleandpracticalcontrolmethod,PIDcontrolhasbeenwidelyusedinsteppermotordrive.Itcomposesthecontroldeviatione(t)accordingtothegivenvaluer(t)andtheactualoutputvaluec(t).Theproportional,integralandderivativeofthedeviationarecombinedtoformthecontrolquantitythroughalinearcombinationtocontrolthecontrolledobject.Theliteratureusesanintegratedpositionsensorinatwo-phasehybridsteppermotor.Basedonthepositiondetectorandvectorcontrol,anautomaticallyadjustablePIspeedcontrollerisdesigned.Thiscontrollercanbeusedundervariableconditions.Providesatisfactorytransientcharacteristics.Accordingtothemathematicalmodelofthesteppermotor,theliteraturedesignsthesteppermotor'sPIDcontrolsystem,andusesthePIDcontrolalgorithmtoobtainthecontrolquantity,therebycontrollingthemotortomovetothespecifiedposition.Finally,simulationsverifythatthecontrolhasgooddynamicresponsecharacteristics.ThePIDcontrollerhastheadvantagesofsimplestructure,strongrobustnessandhighreliability,butitcannoteffectivelydealwiththeuncertaininformationinthesystem.
Atpresent,PIDcontrolismorecombinedwithothercontrolstrategiestoformanewtypeofcompoundcontrolwithintelligence.Thiskindofintelligentcompoundcontrolhastheabilityofself-learning,self-adaptationandself-organization.Itcanautomaticallyidentifythecontrolledprocessparameters,automaticallyadjustthecontrolparameters,adapttothechangesofthecontrolledprocessparameters,andatthesametimehavethecharacteristicsofaconventionalPIDcontroller.
Adaptivecontrol
Adaptivecontrolisabranchofthefieldofautomaticcontroldevelopedinthe1950s.Itisproducedinordertoobtainahigh-performancecontrollerwhenthedynamiccharacteristicsareunknowableorunpredictablechangesoccurwiththecomplexityofthecontrolobject.Itsmainadvantagesareeasyimplementationandfastadaptivespeed,whichcaneffectivelyovercometheinfluencecausedbytheslowchangeoftheparametersofthemotormodel.Itistheoutputsignaltotrackthereferencesignal.Researchersintheliteraturehavederivedgloballystableadaptivecontrolalgorithmsbasedonthelinearorapproximatelylinearmodelofthesteppermotor.Thesecontrolalgorithmsareheavilydependentontheparametersofthemotormodel.Theliteraturecombinesclosed-loopfeedbackcontrolandadaptivecontroltodetectthepositionandspeedoftherotor.Throughfeedbackandadaptiveprocessing,thedrivingpulsetrainisautomaticallysentoutaccordingtotheoptimizedliftingoperationcurve,whichimprovesthedragtorquecharacteristicsofthemotor.Makethemotorobtainmoreprecisepositioncontrolandhigherandmorestablespeed.
Atpresent,manyscholarscombineadaptivecontrolwithothercontrolmethodstosolvetheshortcomingsofpureadaptivecontrol.Therobustadaptivelow-speedservocontrollerdesignedintheliteratureensuresthemaximumcompensationofthesteeringtorqueandthelow-speedandhigh-precisiontrackingcontrolperformanceoftheservosystem.TheadaptivefuzzyPIDcontrollerrealizedintheliteraturecanadjustPIDparametersonlinethroughfuzzyinferenceaccordingtothechangeofinputerroranderrorrateofchange,andrealizetheadaptivecontrolofsteppermotor,therebyeffectivelyimprovingtheresponsetimeandcalculationaccuracyofthesystem.Andanti-interference.
Vectorcontrol
Vectorcontrolisthetheoreticalbasisofmodernmotorhigh-performancecontrol,whichcanimprovethetorquecontrolperformanceofthemotor.Itdividesthestatorcurrentintoexcitationcomponentandtorquecomponenttocontrolseparatelythroughfieldorientation,soastoobtaingooddecouplingcharacteristics.Therefore,vectorcontrolneedstocontrolboththeamplitudeofthestatorcurrentandthephaseofthecurrent.Sincethesteppermotornotonlyhasthemainelectromagnetictorque,butalsothereluctancetorquegeneratedbythedoubleconvexstructure,andtheinternalmagneticfieldstructureiscomplex,andthenonlinearityismuchmoreseriousthanthegeneralmotor,soitsvectorcontrolisalsomorecomplicated.Themathematicalmodelofthedqaxisofthetwo-phasehybridsteppingmotorisderived.Thepermanentmagnetfluxlinkageoftherotorisusedastheorientationcoordinatesystem.system.Thesystemusessensorstodetectthewindingcurrentandrotationpositionofthemotor,andusesthePWMmethodtocontrolthemotorwindingcurrent.Thepaperderivesthetwo-phasehybridsteppingmotormodelbasedonthemagneticnetwork,givesthestructureofitsvectorcontrolpositionservosystem,andusestheneuralnetworkmodeltorefertotheadaptivecontrolstrategytocompensatetheuncertainfactorsinthesysteminrealtime.Torque/currentvectorcontrolrealizeshigh-efficiencycontrolofthemotor.
Applicationofintelligentcontrol
Intelligentcontroldoesnotrelyonordoesnotcompletelyrelyonthemathematicalmodelofthecontrolledobject,andonlycontrolsaccordingtotheactualeffect,andhastheabilitytoconsidertheuncertaintyofthesysteminthecontrolAndaccuracy,breakingthroughthetraditionalcontrolframeworkthatmustbebasedonmathematicalmodels.Atpresent,themorematureapplicationsofintelligentcontrolinsteppermotorsystemsaretheintegrationoffuzzylogiccontrol,neuralnetworkandintelligentcontrol.
Fuzzycontrol
Fuzzycontrolisbasedonthefuzzymodelofthecontrolledobjectandusestheapproximatereasoningofthefuzzycontrollertorealizesystemcontrol.Methods.Asacontrolmethodthatdirectlysimulatestheresultsofhumanthinking,fuzzycontrolhasbeenwidelyusedinthefieldofindustrialcontrol.Comparedwithconventionalcontrol,fuzzycontroldoesnotrequireprecisemathematicalmodels,andhasstrongrobustnessandadaptability,soitissuitableforthecontrolofnonlinear,time-varying,andtime-delaysystems.Anapplicationexampleoffuzzycontrolinthespeedcontrolofatwo-phasehybridsteppingmotorisgiven.Thesystemadoptsadvancedanglecontrol,nomathematicalmodelisneededinthedesign,andthespeedresponsetimeisshort.
Neuralnetworkcontrol
Neuralnetworkisamethodthatusesalargenumberofneuronstoadjustaccordingtoacertaintopologyandlearning.Itcanfullyapproximatearbitrarilycomplexnonlinearsystems,canlearnandadapttounknownoruncertainsystems,andhasstrongrobustnessandfaulttolerance,soithasbeenwidelyusedinsteppermotorsystems.Theneuralnetworkisusedtoachievethebestsubdivisioncurrentofthesteppermotor,theBayesregularizationalgorithmisusedinthelearning,andtheweightadjustmenttechnologyisusedtoavoidthemultilayerforwardneuralnetworkfromfallingintothelocalminimumpoint,whicheffectivelysolvestheproblemofequalstepanglefineness.Sub-issues.