年4月19日基于單片機的步進電機電路控制設計英文文獻及翻譯文檔僅供參考TheSteppermotorcontrolcircuitbebasedonSinglechipmicrocomputerTheAT89C51isalow-power,high-performanceCMOS8-bitmicrocomputerwith4KbytesofFlashprogrammableanderasablereadonlymemory(PEROM).ThedeviceismanufacturedusingAtmel’shigh-densitynonvolatilememorytechnologyandiscompatiblewiththeindustry-standardMCS-51instructionsetandpinout.Theon-chipFlashallowstheprogrammemorytobereprogrammedin-systemorbyaconventionalnonvolatilememoryprogrammer.Bycombiningaversatile8-bitCPUwithFlashonamonolithicchip,theAtmelAT89C51isapowerfulmicrocomputerwhichprovidesahighly-flexibleandcost-effectivesolutiontomanyembeddedcontrolapplications.FunctioncharacteristicTheAT89C51providesthefollowingstandardfeatures:4KbytesofFlash,128bytesofRAM,32I/Olines,two16-bittimer/counters,afivevectortwo-levelinterruptarchitecture,afullduplexserialport,on-chiposcillatorandclockcircuitry.Inaddition,theAT89C51isdesignedwithstaticlogicforoperationdowntozerofrequencyandsupportstwosoftwareselectablepowersavingmodes.TheIdleModestopstheCPUwhileallowingtheRAM,timer/counters,serialportandinterruptsystemtocontinuefunctioning.ThePower-downModesavestheRAMcontentsbutfreezestheoscillatordisablingallotherchipfunctionsuntilthenexthardwarereset.PinDescriptionVCC：Supplyvoltage.GND：Ground.Port0：Port0isan8-bitopen-drainbi-directionalI/Oport.Asanoutputport,eachpincansinkeightTTLinputs.When1sarewrittentoport0pins,thepinscanbeusedashighimpedanceinputs.Port0mayalsobeconfiguredtobethemultiplexedloworderaddress/databusduringaccessestoexternalprogramanddatamemory.InthismodeP0hasinternalpullups.Port0alsoreceivesthecodebytesduringFlashprogramming,andoutputsthecodebytesduringprogramverification.Externalpullupsarerequiredduringprogramverification.Port1Port1isan8-bitbi-directionalI/Oportwithinternalpullups.ThePort2Port2isan8-bitbi-directionalI/Oportwithinternalpullups.ThePort3Port3isan8-bitbi-directionalI/Oportwithinternalpullups.ThePort3outputbufferscansink/sourcefourTTLinputs.When1sarewrittentoPort3pinstheyarepulledhighbytheinternalpullupsandcanbeusedasinputs.Asinputs,Port3pinsthatareexternallybeingpulledlowwillsourcecurrent(IIL)becauseofthepullups.Port3alsoservesthefunctionsofvariousspecialfeaturesoftheATPort3alsoreceivessomecontrolsignalsforFlashprogrammingandverification.RSTResetinput.Ahighonthispinfortwomachinecycleswhiletheoscillatorisrunningresetsthedevice.ALE/PROGAddressLatchEnableoutputpulseforlatchingthelowbyteoftheaddressduringaccessestoexternalmemory.Thispinisalsotheprogrampulseinput(PROG)duringFlashprogramming.InnormaloperationALEisemittedataconstantrateof1/6theoscillatorfrequency,andmaybeusedforexternaltimingorclockingpurposes.Note,however,thatoneALEpulseisskippedduringeachaccesstoexternalDataMemory.Ifdesired,ALEoperationcanbedisabledbysettingbit0ofSFRlocation8EH.Withthebitset,ALEisactiveonlyduringaMOVXorMOVCinstruction.Otherwise,thepinisweaklypulledhigh.SettingtheALE-disablebithasnoeffectifthemicrocontrollerisinexternalexecutionmode.PSENProgramStoreEnableisthereadstrobetoexternalprogrammemory.WhentheAT89C51isexecutingcodefromexternalprogrammemory,PSENisactivatedtwiceeachmachinecycle,exceptthattwoPSENactivationsareskippedduringeachaccesstoexternaldatamemory.EA/VPPExternalAccessEnable.EAmustbestrappedtoGNDinordertoenablethedevicetofetchcodefromexternalprogrammemorylocationsstartingat0000HuptoFFFFH.Note,however,thatiflockbit1isprogrammed,EAwillbeinternallylatchedonreset.EAshouldbestrappedtoVCCforinternalprogramexecutions.Thispinalsoreceivesthe12-voltprogrammingenablevoltage(VPP)duringFlashprogramming,forpartsthatrequire12-voltVPP.XTAL1Inputtotheinvertingoscillatoramplifierandinputtotheinternalclockoperatingcircuit.XTAL2Outputfromtheinvertingoscillatoramplifier.OscillatorCharacteristicsXTAL1andXTAL2aretheinputandoutput,respectively,ofaninvertingamplifierwhichcanbeconfiguredforuseasanon-chiposcillator,asshowninFigure1.Eitheraquartzcrystalorceramicresonatormaybeused.Todrivethedevicefromanexternalclocksource,XTAL2shouldbeleftunconnectedwhileXTAL1isdrivenasshowninFigure2.Therearenorequirementsonthedutycycleoftheexternalclocksignal,sincetheinputtotheinternalclockingcircuitryisthroughadivide-by-twoflip-flop,butminimumandmaximumvoltagehighandlowtimespecificationsmustbeobserved.Figure1.OscillatorConnectionsFigure2.ExternalClockDriveConfigurationIdleModeInidlemode,theCPUputsitselftosleepwhilealltheonchipperipheralsremainactive.Themodeisinvokedbysoftware.Thecontentoftheon-chipRAMandallthespecialfunctionsregistersremainunchangedduringthismode.Theidlemodecanbeterminatedbyanyenabledinterruptorbyahardwarereset.Itshouldbenotedthatwhenidleisterminatedbyahardwarereset,thedevicenormallyresumesprogramexecution,fromwhereitleftoff,uptotwomachinecyclesbeforetheinternalresetalgorithmtakescontrol.On-chiphardwareinhibitsaccesstointernalRAMinthisevent,butaccesstotheportpinsisnotinhibited.ToeliminatethepossibilityofanunexpectedwritetoaportpinwhenIdleisterminatedbyreset,theinstructionfollowingtheonethatinvokesIdleshouldnotbeonethatwritestoaportpinortoexternalmemory.Power-downModeInthepower-downmode,theoscillatorisstopped,andtheinstructionthatinvokespower-downisthelastinstructionexecuted.Theon-chipRAMandSpecialFunctionRegistersretaintheirvaluesuntilthepower-downmodeisterminated.Theonlyexitfrompower-downisahardwarereset.ResetredefinestheSFRsbutdoesnotchangetheon-chipRAM.TheresetshouldnotbeactivatedbeforeVCCisrestoredtoitsnormaloperatinglevelandmustbeheldactivelongenoughtoallowtheoscillatortorestartandstabilize.ProgramMemoryLockBitsOnthechiparethreelockbitswhichcanbeleftunprogrammed(U)orcanbeprogrammed(P)toobtaintheadditionalfeatureslistedinthetablebelow.Whenlockbit1isprogrammed,thelogiclevelattheEApinissampledandlatchedduringreset.Ifthedeviceispoweredupwithoutareset,thelatchinitializestoarandomvalue,andholdsthatvalueuntilresetisactivated.ItisnecessarythatthelatchedvalueofEAbeinagreementwiththecurrentlogiclevelatthatpininorderforthedevicetofunctionproperly.IntroductionSteppermotorsareelectromagneticincremental-motiondeviceswhichconvertdigitalpulseinputstoanalogangleoutputs.Theirinherentsteppingabilityallowsforaccuratepositioncontrolwithoutfeedback.Thatis,theycantrackanysteppositioninopen-loopmode,consequentlynofeedbackisneededtoimplementpositioncontrol.SteppermotorsdeliverhigherpeaktorqueperunitweightthanDCmotors;inaddition,theyarebrushlessmachinesandthereforerequirelessmaintenance.Allofthesepropertieshavemadesteppermotorsaveryattractiveselectioninmanypositionandspeedcontrolsystems,suchasincomputerharddiskdriversandprinters,XY-tables,robotmanipulators,etc.Althoughsteppermotorshavemanysalientproperties,theysufferfromanoscillationorunstablephenomenon.Thisphenomenonseverelyrestrictstheiropen-loopdynamicperformanceandapplicableareawherehighspeedoperationisneeded.Theoscillationusuallyoccursatsteppingrateslowerthan1000pulse/s,andhasbeenrecognizedasamid-frequencyinstabilityorlocalinstability[1],oradynamicinstability[2].Inaddition,thereisanotherkindofunstablephenomenoninsteppermotors,thatis,themotorsusuallylosesynchronismathighersteppingrates,eventhoughloadtorqueislessthantheirpull-outtorque.Thisphenomenonisidentifiedashigh-frequencyinstabilityinthispaper,becauseitappearsatmuchhigherfrequenciesthanthefrequenciesatwhichthemid-frequencyoscillationoccurs.Thehigh-frequencyinstabilityhasnotbeenrecognizedaswidelyasmid-frequencyinstability,andthereisnotyetamethodtoevaluateit.Mid-frequencyoscillationhasbeenrecognizedwidelyforaverylongtime,however,acompleteunderstandingofithasnotbeenwellestablished.Thiscanbeattributedtothenonlinearitythatdominatestheoscillationphenomenonandisquitedifficulttodealwith.384L.CaoandH.M.SchwartzMostresearchershaveanalyzeditbasedonalinearizedmodel[1].Althoughinmanycases,thiskindoftreatmentsisvalidoruseful,atreatmentbasedonnonlineartheoryisneededinordertogiveabetterdescriptiononthiscomplexphenomenon.Forexample,basedonalinearizedmodelonecanonlyseethatthemotorsturntobelocallyunstableatsomesupplyfrequencies,whichdoesnotgivemuchinsightintotheobservedoscillatoryphenomenon.Infact,theoscillationcannotbeassessedunlessoneusesnonlineartheory.Therefore,itissignificanttousedevelopedmathematicaltheoryonnonlineardynamicstohandletheoscillationorinstability.ItisworthnotingthatTaftandGauthier[3],andTaftandHarned[4]usedmathematicalconceptssuchaslimitcyclesandseparatricesintheanalysisofoscillatoryandunstablephenomena,andobtainedsomeveryinstructiveinsightsintothesocalledlossofsynchronousphenomenon.Nevertheless,thereisstillalackofacomprehensivemathematicalanalysisinthiskindofstudies.Inthispaperanovelmathematicalanalysisisdevelopedtoanalyzetheoscillationsandinstabilityinsteppermotors.Thefirstpartofthispaperdiscussesthestabilityanalysisofsteppermotors.Itisshownthatthemid-frequencyoscillationcanbecharacterizedasabifurcationphenomenon(Hopfbifurcation)ofnonlinearsystems.OneofcontributionsofthispaperistorelatethemidfrequencyoscillationtoHopfbifurcation,thereby,theexistenceoftheoscillationisprovedtheoreticallybyHopftheory.High-frequencyinstabilityisalsodiscussedindetail,andanovelquantityisintroducedtoevaluatehigh-frequencystability.Thisquantityisveryeasytocalculate,andcanbeusedasacriteriatopredicttheonsetofthehigh-frequencyinstability.Experimentalresultsonarealmotorshowtheefficiencyofthisanalyticaltool.Thesecondpartofthispaperdiscussesstabilizingcontrolofsteppermotorsthroughfeedback.Severalauthorshaveshownthatbymodulatingthesupplyfrequency[5],themidfrequencyinstabilitycanbeimproved.Inparticular,PickupandRussell[6,7]havepresentedadetailedanalysisonthefrequencymodulationmethod.Intheiranalysis,Jacobiserieswasusedtosolveaordinarydifferentialequation,andasetofnonlinearalgebraicequationshadtobesolvednumerically.Inaddition,theiranalysisisundertakenforatwo-phasemotor,andtherefore,theirconclusionscannotapplieddirectlytooursituation,whereathree-phasemotorwillbeconsidered.Here,wegiveamoreelegantanalysisforstabilizingsteppermotors,wherenocomplexmathematicalmanipulationisneeded.Inthisanalysis,ad–qmodelofsteppermotorsisused.Becausetwo-phasemotorsandthree-phasemotorshavethesameq–dmodelandtherefore,theanalysisisvalidforbothtwo-phaseandthree-phasemotors.Uptodate,itisonlyrecognizedthatthemodulationmethodisneededtosuppressthemidfrequencyoscillation.Inthispaper,itisshownthatthismethodisnotonlyvalidtoimprovemid-frequencystability,butalsoeffectivetoimprovehigh-frequencystability.2.DynamicModelofStepperMotorsThesteppermotorconsideredinthispaperconsistsofasalientstatorwithtwo-phaseorthreephasewindings,andapermanent-magnetrotor.Asimplifiedschematicofathree-phasemotorwithonepole-pairisshowninFigure1.Thesteppermotorisusuallyfedbyavoltage-sourceinverter,whichiscontrolledbyasequenceofpulsesandproducessquare-wavevoltages.Thismotoroperatesessentiallyonthesameprincipleasthatofsynchronousmotors.Oneofmajoroperatingmannerforsteppermotorsisthatsupplyingvoltageiskeptconstantandfrequencyofpulsesischangedataverywiderange.Underthisoperatingcondition,oscillationandinstabilityproblemsusuallyarise.Figure1.Schematicmodelofathree-phasesteppermotorAmathematicalmodelforathree-phasesteppermotorisestablishedusingq–dframereferencetransformation.Thevoltageequationsforthree-phasewindingsaregivenbyva=Ria+L*dia/dt?M*dib/dt?M*dic/dt+dλpma/dt,vb=Rib+L*dib/dt?M*dia/dt?M*dic/dt+dλpmb/dt,vc=Ric+L*dic/dt?M*dia/dt?M*dib/dt+dλpmc/dt,whereRandLaretheresistanceandinductanceofthephasewindings,andMisthemutualinductancebetweenthephasewindings._pma,_pmband_pmcaretheflux-linkagesofthephasesduetothepermanentmagnet,andcanbeassumedtobesinusoidfunctionsofrotorposition_asfollowλpma=λ1sin(Nθ),λpmb=λ1sin(Nθ?2π/3),λpmc=λ1sin(Nθ-2π/3),whereNisnumberofrotorteeth.Thenonlinearityemphasizedinthispaperisrepresentedbytheaboveequations,thatis,theflux-linkagesarenonlinearfunctionsoftherotorposition.Byusingtheq;dtransformation,theframeofreferenceischangedfromthefixedphaseaxestotheaxesmovingwiththerotor(refertoFigure2).Transformationmatrixfromthea;b;cframetotheq;dframeisgivenby[8]Forexample,voltagesintheq;dreferencearegivenbyInthea;b;creference,onlytwovariablesareindependent(iaCibCicD0);therefore,theabovetransformationfromthreevariablestotwovariablesisallowable.Applyingtheabovetransformationtothevoltageequations(1),thetransferredvoltageequationintheq;dframecanbeobtainedasvq=Riq+L1*diq/dt+NL1idω+Nλ1ω,vd=Rid+L1*did/dt?NL1iqω,(5)Figure2.a,b,candd,qreferenceframewhereL1DLCM,and!isthespeedoftherotor.Itcanbeshownthatthemotor’storquehasthefollowingform[2]T=3/2Nλ1iqTheequationofmotionoftherotoriswrittenasJ*dω/dt=3/2*Nλ1iq?Bfω–Tl,whereBfisthecoefficientofviscousfriction,andTlrepresentsloadtorque,whichisassumedtobeaconstantinthispaper.Inordertoconstitutethecompletestateequationofthemotor,weneedanotherstatevariablethatrepresentsthepositionoftherotor.Forthispurposethesocalledloadangle_[8]isusuallyused,whichsatisfiesthefollowingequationDδ/dt=ω?ω0,where!0issteady-statespeedofthemotor.Equations(5),(7),and(8)constitutethestatespacemodelofthemotor,forwhichtheinputvariablesarethevoltagesvqandvd.Asmentionedbefore,steppermotorsarefedbyaninverter,whoseoutputvoltagesarenotsinusoidalbutinsteadaresquarewaves.However,becausethenon-sinusoidalvoltagesdonotchangetheoscillationfeatureandinstabilityverymuchifcomparedtothesinusoidalcase(aswillbeshowninSection3,theoscillationisduetothenonlinearityofthemotor),forthepurposesofthispaperwecanassumethesupplyvoltagesaresinusoidal.Underthisassumption,wecangetvqandvdasfollowsvq=Vmcos(Nδ),vd=Vmsin(Nδ),whereVmisthemaximumofthesinewave.Withtheaboveequation,wehavechangedtheinputvoltagesfromafunctionoftimetoafunctionofstate,andinthiswaywecanrepresentthedynamicsofthemotorbyaautonomoussystem,asshownbelow.Thiswillsimplifythemathematicalanalysis.FromEquations(5),(7),and(8),thestate-spacemodelofthemotorcanbewritteninamatrixformasfollows?=F(X,u)=AX+Fn(X)+Bu,(10)whereXDTiqid!_UT,uDT!1TlUTisdefinedastheinput,and!1DN!0isthesupplyfrequency.TheinputmatrixBisdefinedbyThematrixAisthelinearpartofF._/,andisgivenbyFn.X/representsthenonlinearpartofF._/,andisgivenbyTheinputtermuisindependentoftime,andthereforeEquation(10)isautonomous.TherearethreeparametersinF.X;u/,theyarethesupplyfrequency!1,thesupplyvoltagemagnitudeVmandtheloadtorqueTl.Theseparametersgovernthebehaviourofthesteppermotor.Inpractice,steppermotorsareusuallydriveninsuchawaythatthesupplyfrequency!1ischangedbythecommandpulsetocontrolthemotor’sspeed,whilethesupplyvoltageiskeptconstant.Therefore,weshallinvestigatetheeffectofparameter!1.3.BifurcationandMid-FrequencyOscillationBysetting!D!0,theequilibriaofEquation(10)aregivenasand'isitsphaseangledefinedbyφ=arctan(ω1L1Equations(12)and(13)indicatethatmultipleequilibriaexist,whichmeansthattheseequilibriacanneverbegloballystable.OnecanseethattherearetwogroupsofequilibriaasshowninEquations(12)and(13).ThefirstgrouprepresentedbyEquation(12)correspondstotherealoperatingconditionsofthemotor.ThesecondgrouprepresentedbyEquation(13)isalwaysunstableanddoesnotrelatetotherealoperatingconditions.Inthefollowing,wewillconcentrateontheequilibriarepresentedbyEquation(12).基于單片機的步進電機電路控制設計89C51是一種帶4K字節閃爍可編程可擦除只讀存儲器（FPEROM—FalshProgrammableandErasableReadOnlyMemory）的低電壓、高性能CMOS8位微處理器，俗稱單片機。該器件采用ATMEL高密度非易失存儲器制造技術制造，與工業標準的MCS-51指令集和輸出管腳相兼容。由于將多功能8位CPU和閃爍存儲器組合在單個芯片中，ATMEL的89C51是一種高效微控制器，89C2051是它的一種精簡版本。89C單片機為很多嵌入式控制系統提供了一種靈活性高且價廉的方案。功能特點·與MCS-51兼容·4K字節可編程閃爍存儲器·壽命：1000寫/擦循環·數據保留時間：·全靜態工作：0Hz-24MHz·三級程序存儲器鎖定·128*8位內部RAM·32可編程I/O線·兩個16位定時器/計數器·5個中斷源·可編程串行通道·低功耗的閑置和掉電模式·片內振蕩器和時鐘電路管腳說明VCC：供電電壓。GND：接地。P0口：P0口為一個8位漏級開路雙向I/O口，每腳可吸收8TTL門電流。當P1口的管腳第一次寫1時，被定義為高阻輸入。P0能夠用于外部程序數據存儲器，它能夠被定義為數據/地址的低八位。在FIASH編程時，P0口作為原碼輸入口，當FIASH進行校驗時，P0輸出原碼，此時P0外部必須被拉高。P1口：P1口是一個內部提供上拉電阻的8位雙向I/O口，P1口緩沖器能接收輸出4TTL門電流。P1口管腳寫入1后，被內部上拉為高，可用作輸入，P1口被外部下拉為低電平時，將輸出電流，這是由于內部上拉的緣故。在FLASH編程和校驗時，P1口作為第八位地址接收。P2口：P2口為一個內部上拉電阻的8位雙向I/O口，P2口緩沖器可接收，輸出4個TTL門電流，當P2口被寫“1”時，其管腳被內部上拉電阻拉高，且作為輸入。并因此作為輸入時，P2口的管腳被外部拉低，將輸出電流。這是由于內部上拉的緣故。P2口當用于外部程序存儲器或16位地址外部數據存儲器進行存取時，P2口輸出地址的高八位。在給出地址“1”時，它利用內部上拉優勢，當對外部八位地址數據存儲器進行讀寫時，P2口輸出其特殊功能寄存器的內容。P2口在FLASH編程和校驗時接收高八位地址信號和控制信號。P3口：P3口管腳是8個帶內部上拉電阻的雙向I/O口，可接收輸出4個TTL門電流。當P3口寫入“1”后，它們被內部上拉為高電平，并用作輸入。作為輸入，由于外部下拉為低電平，P3口將輸出電流（ILL）這是由于上拉的緣故。P3口也可作為AT89C51的一些特殊功能口.口管腳備選功能P3.0RXD（串行輸入口）P3.1TXD（串行輸出口）P3.2/INT0（外部中斷0）P3.3/INT1（外部中斷1）P3.4T0（記時器0外部輸入）P3.5T1（記時器1外部輸入）P3.6/WR（外部數據存儲器寫選通）P3.7/RD（外部數據存儲器讀選通）P3口同時為閃爍編程和編程校驗接收一些控制信號。RST：復位輸入。當振蕩器復位器件時，要保持RST腳兩個機器周期的高電平時間。ALE/PROG：當訪問外部存儲器時，地址鎖存允許的輸出電平用于鎖存地址的地位字節。在FLASH編程期間，此引腳用于輸入編程脈沖。在平時，ALE端以不變的頻率周期輸出正脈沖信號，此頻率為振蕩器頻率的1/6。因此它可用作對外部輸出的脈沖或用于定時目的。然而要注意的是：每當用作外部數據存儲器時，將跳過一個ALE脈沖。如想禁止ALE的輸出可在SFR8EH地址上置0。此時，ALE只有在執行MOVX，MOVC指令是ALE才起作用。另外，該引腳被略微拉高。如果微處理器在外部執行狀態ALE禁止，置位無效。/PSEN：外部程序存儲器的選通信號。在由外部程序存儲器取指期間，每個機器周期兩次/PSEN有效。但在訪問外部數據存儲器時，這兩次有效的/PSEN信號將不出現。/EA/VPP：當/EA保持低電平時，則在此期間外部程序存儲器（0000H-FFFFH），不論是否有內部程序存儲器。注意加密方式1時，/EA將內部鎖定為RESET；當/EA端保持高電平時，此間內部程序存儲器。在FLASH編程期間，此引腳也用于施加12V編程電源（VPP）。XTAL1：反向振蕩放大器的輸入及內部時鐘工作電路的輸入。XTAL2：來自反向振蕩器的輸出。振蕩器特性XTAL1和XTAL2分別為反向放大器的輸入和輸出。該反向放大器能夠配置為片內振蕩器。石晶振蕩和陶瓷振蕩均可采用。如采用外部時鐘源驅動器件，XTAL2應不接。由于輸入至內部時鐘信號要經過一個二分頻觸發器，因此對外部時鐘信號的脈寬無任何要求，但必須保證脈沖的高低電平要求的寬度。Figure1.OscillatorConnectionsFigure2.ExternalClockDrive芯片擦除整個PEROM陣列和三個鎖定位的電擦除可經過正確的控制信號組合，并保持ALE管腳處于低電平10ms來完成。在芯片擦操作中，代碼陣列全被寫“1”且在任何非空存儲字節被重復編程以前，該操作必須被執行。另外，AT89C51設有穩態邏輯，能夠在低到零頻率的條件下靜態邏輯，支持兩種軟件可選的掉電模式。在閑置模式下，CPU停止工作。但RAM，定時器，計數器，串口和中斷系統仍在工作。在掉電模式下，保存RAM的內容而且凍結振蕩器，禁止所用其它芯片功能，直到下一個硬件復位為止。空閑模式在空閑模式下,中央處理器把自己睡;所有的微外設保持活躍。該模式調用的軟件。片上的內容的公綿羊、所有的特殊功能寄存器不變在這個模式下。空閑模式能夠終止任何使中斷或由硬件復位。應該指出的是,閑時終止一個硬件復位,設備一般程序執行,從簡歷在它停止兩封,機器周期之前,內部重置算法以控制。樣品的硬件抑制進入內部RAM在這種情況下,但進入港口大頭針空洞。消除這種可能性一個出乎意料的寫信給一個港口銷閑時被終止,由復位、指導證明那個中調用一個空閑不應該寫端口銷或外部存儲器。Power-down模式在power-down模式下,振子是結束了,但這個指令;用它召喚“power-down是最后的指令執行。這片上的公綿羊、特殊功能寄存器值,直到power-down保留自己的方式終止。唯一的退出,是一家五金power-down重置。SFRs重置重新定義,但不改變樣品的公羊。重置不應該被激活之前VCC回到正常操作水平,都必須保持活躍的時間還不夠久,允許振蕩器來重新啟動和穩定。程序記憶鎖位在芯片上的三個鎖位能夠離開unprogrammed(U)或可編程(P)獲得的額外功能列在下表。當鎖點,1是程序邏輯電平EA銷樣品并就搭在重置。如果這個裝置是開機沒有重置,門閂初始化一個隨機值,認為直到重置價值被激活。加入是必要的值EA是一致的邏輯與當前水平銷為設備正常運作步進電機介紹步進電機是將數字脈沖輸入轉換為模擬角度輸出的電磁增量運動裝置。其內在的步進能力允許沒有反饋的精確位置控制。也就是說，她們能夠在開環模式下跟蹤任何步階位置，因此執行位置控制是不需要任何反饋的。步進電機提供比直流電機每單位更高的峰值扭矩;另外，它們是無電刷電機，因此需要較少的維護。所有這些特性使得步進電機在許多位置和速度控制系統的選擇中非常具有吸引力，例如如在計算機硬盤驅動器和打印機，代理表，機器人中的應用等.盡管步進電機有許多突出的特性，她們仍遭受振蕩或不穩定現象。這種現象嚴重地限制其開環的動態性能和需要高速運作的適用領域。這種振蕩一般在步進率低于1000脈沖/秒的時候發生，并已被確認為中頻不穩定或局部不穩定[1]，或者動態不穩定[2]。另外，步進電機還有另一種不穩定現象，也就是在步進率較高時，即使負荷扭矩小于其牽出扭矩，電動機也常常不同步。該文中將這種現象確定為高頻不穩定性，因為它以比在中頻振蕩現象中發生的頻率更高的頻率出現。高頻不穩定性不像中頻不穩定性那樣被廣泛接受，而且還沒有一個方法來評估它。中頻振蕩已經被廣泛地認識了很長一段時間，可是，一個完整的了解還沒有牢固確立。這能夠歸因于支配振蕩現象的非線性是相當困難處理的。大多數研究人員在線性模型基礎上分析它[1]。盡管在許多情況下，這種處理方法是有效的或有益的，但為了更好地描述這一復雜的現象，在非線性理論基礎上的處理方法也是需要的。例如，基于線性模型只能看到電動機在某些供應頻率下轉向局部不穩定，并不能使被觀測的振蕩現象更多深入。事實上，除非有人利用非線性理論，否則振蕩不能評估。窗體頂端窗體底端因此，在非線性動力學上利用被發展的數學理論處理振蕩或不穩定是很重要的。值得指出的是，Taft和Gauthier[3]，還有Taft和Harned[4]使用的諸如在振蕩和不穩定現象的分析中的極限環和分界線之類的數學概念，并取得了關于所謂非同步現象的一些非常有啟發性的看法。盡管如此，在這項研究中依然缺乏一個全面的數學分析。本文一種新的數學分被開發了用于分析步進電機的振動和不穩定性。本文的第一部分討論了步進電機的穩定性分析。結果表明，中頻振蕩可定性為一種非線性系統的分叉現象（霍普夫分叉）。本文的貢獻之一是將中頻振蕩與霍普夫分叉聯系起來，從而霍普夫理論從理論上證明了振蕩的存在性。高頻不穩定性也被詳細討論了，并介紹了一種新型的量來評估高頻穩定。這個量是很容易計算的，而且能夠作為一種標準來預測高頻不穩定性的發生。在一個真實電動機上的實驗結果顯示了該分析工具的有效性。本文的第二部分經過反饋討論了步進電機的穩定性控制。一些設計者已表明，經過調節供應頻率[5]，中頻不穩定性能夠得到改進。特別是Pickup和Russell[6，7]都在頻率調制的方法上提出了詳細的分析。在她們的分析中，雅可比級數用于解決常微分方程和一組數值有待解決的非線性代數方程組。另外，她們的分析負責的是雙相電動機，因此，她們的結論不能直接適用于我們需要考慮三相電動機的情況。在這里，我們提供一個沒有必要處理任何復雜數學的更簡潔的穩定步進電機的分析。在這種分析中，使用的是d-q模型的步進電機。由于雙相電動機和三相電動機具有相同的d-q模型，因此，這種分