同步电动机外文翻译文献

PAGEPAGE1同步电动机外文翻译文献同步电动机外文翻译文献(文档含中英文对照即英文原文和中文翻译)SynchronousmotorAbstract：Inrecentdecades,withthepowerelectronics,microelectronicstechnologyandthedevelopmentofmoderncontroltheory,mediumandsmallpowermotorsintheindustrialandagriculturalproductionandpeople'sdailylivesareverybroadapplication.Particularlyinthetownshipenterprisesandhouseholdelectricalappliances,needalargenumberofmediumandsmall-powermotors.Becauseofthismotordevelopmentandwideapplication,itsuse,maintenanceandrepairworkhasbecomeincreasinglyimportant，Herearejustontheknowledgeofsynchronousmotor1.PrincipleofoperationInordertounderstandtheprincipleofoperationofasynchronousmotor,letusexaminewhathappensifweconnectthearmaturewinding(laidoutinthestator)ofa3-phasesynchronousmachinetoasuitablebalanced3-phasesourceandthefieldwindingtoaD.Csourceofappropriatevoltage.ThecurrentflowingthroughthefieldcoilswillsetupstationarymagneticpolesofalternateNorthandSouth.(forconvenienceletusassumeasalientpolerotor,asshowninFig.50).Ontheotherhand,the3-phasecurrentsflowinginthearmaturewindingproducearotatingmagneticfieldrotatingatsynchronousspeed.InotherwordstherewillbemovingNorthandSouthpolesestablishedinthestatorduetothe3-phasecurrentsi.eatanylocationinthestatortherewillbeaNorthpoleatsomeinstantoftimeanditwillbecomeaSouthpoleafteratimeperiodcorrespondingtohalfacycle.(afteratime=12f,wheref=frequencyofthesupply).LetusassumethatthestationarySouthpoleintherotorisalignedwiththeNorthpoleinthestatormovinginclockwisedirectionataparticularinstantoftime,asshowninFig50.ThesetwopolesgetattractedandFigure50:Forceofattractionbetweenstatorpolesandrotorpoles-resultinginproductionoftorqueinclockwisedirectiontrytomaintainthisalignment(asperLenz’slaw)andhencetherotorpoletriestofollowthestatorpoleastheconditionsaresuitablefortheproductionoftorqueintheclockwisedirection.Howevertherotorcannotmoveinstantaneouslyduetoitsmechanicalinertia,andsoitneedssometimetomove.Inthemeantime,thestatorpolewouldquickly(atimedurationcorrespondingtohalfacycle)changeitspolarityandbecomesaSouthpole。SotheforceofattractionwillnolongerbepresentandinsteadthelikepolesexperienceaforceofrepulsionasshowninFig.51.Inotherwords,theconditionsarenowsuitablefortheFigure51:Forceofrepulsionbetweenstatorpolesandrotorpoles-resultinginproductionoftorqueinanticlockwisedirectionproductionoftorqueintheanticlockwisedirection.EventhisconditionwillnotlastlongerasthestatorpolewouldagainchangetoNorthpoleafteratimeof12f.Thustherotorwillexperienceanalternatingforcewhichtriestomoveitclockwiseandanticlockwiseattwicethefrequencyofthesupply,i.e.atintervalscorrespondingto12fseconds.Asthisdurationisquitesmallcomparedtothemechanicaltimeconstantoftherotor,therotorcannotrespondandmoveinanydirection.Therotorcontinuestobestationaryonly.Onthecontraryiftherotorisbroughttonearsynchronousspeedbysomeexternalmeanssayasmallmotor(knownasponymotor-whichcouldbeaD.CorACinductionrotor)mountedonthesameshaftasthatoftherotor,therotorpolesgetlockedtotheunlikepolesinthestatorandtherotorcontinuestorunatthesynchronousspeedevenifthesupplytotheponymotorisdisconnected.Thusthesynchronousrotorcannotstartrotatingonitsownorusuallywesaythatthesynchronousrotorhasnostartingtorque.So,somespecialprovisionhastobemadeeitherinsidethemachineoroutsideofthemachinesothattherotorisbroughttonearaboutitssynchronousspeed.Atthattime,ifthearmatureissuppliedwithelectricalpower,therotorcanpullintostepandcontinuetooperateatitssynchronousspeed.Someofthecommonlyusedmethodsforstartingsynchronousrotoraredescribedinthefollowingsection.2.MethodsofstartingsynchronousmotorBasicallytherearethreemethodsthatareusedtostartasynchronousmotor:•Toreducethespeedoftherotatingmagneticfieldofthestatortoalowenoughvaluethattherotorcaneasilyaccelerateandlockinwithitduringonehalf-cycleoftherotatingmagneticfield’srotation.Thisisdonebyreducingthefrequencyoftheappliedelectricpower.Thismethodisusuallyfollowedinthecaseofinverter-fedsynchronousmotoroperatingundervariablespeeddriveapplications.•Touseanexternalprimemovertoacceleratetherotorofsynchronousmotorneartoitssynchronousspeedandthensupplytherotoraswellasstator.Ofcoursecareshouldbetakentoensurethatthedirectionofrotationoftherotoraswellasthatoftherotatingmagneticfieldofthestatorarethesame.Thismethodisusuallyfollowedinthelaboratory-thesynchronousmachineisstartedasageneratorandisthenconnectedtothesupplymainsbyfollowingthesynchronizationorparallelingprocedure.Thenthepowersupplytotheprimemoverisdisconnectedsothatthesynchronousmachinewillcontinuetooperateasamotor.•Tousedamperwindingsoramortisseurwindingsiftheseareprovidedinthemachine.Thedamperwindingsoramortisseurwindingsareprovidedinmostofthelargesynchronousmotorsinordertonullifytheoscillationsoftherotorwheneverthesynchronousmachineissubjectedtoaperiodicallyvaryingload.Eachofthesemethodsofstartingasynchronousmotoraredescribedbelowindetail.2.1MotorstartingbyreducingthesupplyFrequencyIftherotatingmagneticfieldofthestatorinasynchronousmotorrotatesatalowenoughspeed,therewillbenoproblemfortherotortoaccelerateandtolockinwiththestator’smagneticfield.Thespeedofthestatormagneticfieldcanthenbeincreasedtoitsratedoperatingspeedbygraduallyincreasingthesupplyfrequencyfuptoitsnormal50or60Hzvalue.Thisapproachtostartingofsynchronousmotorsmakesalotofsense,butthereisabigproblem:Wherefromcanwegetthevariablefrequencysupply?Theusualpowersupplysystemsgenerallyregulatethefrequencytobe50or60Hzasthecasemaybe.However,variable-frequencyvoltagesourcecanbeobtainedfromadedicatedgeneratoronlyintheoldendaysandsuchasituationwasobviouslyimpracticalexceptforveryunusualorspecialdriveapplications.Butthepresentdaysolidstatepowerconvertersofferaneasysolutiontothis.Wenowhavetherectifier-inverterandcycloconverters,whichcanbeusedtoconvertaconstantfrequencyACsupplytoavariablefrequencyACsupply.Withthedevelopmentofsuchmodernsolid-statevariable-frequencydrivepackages,itisthuspossibletocontinuouslycontrolthefrequencyofthesupplyconnectedtothesynchronousmotorallthewayfromafractionofahertzuptoandevenabovethenormalratedfrequency.Ifsuchavariable-frequencydriveunitisincludedinamotor-controlcircuittoachievespeedcontrol,thenstartingthesynchronousmotorisveryeasy-simplyadjustthefrequencytoaverylowvalueforstarting,andthenraiseituptothedesiredoperatingfrequencyfornormalrunning.Whenasynchronousmotorisoperatedataspeedlowerthantheratedspeed,itsinternalgeneratedvoltage(usuallycalledthecounterEMF)EA=Kwillbesmallerthannormal.Assuchtheterminalvoltageappliedtothemotormustbereducedproportionallywiththefrequencyinordertokeepthestatorcurrentwithintheratedvalue.Generally,thevoltageinanyvariable-frequencypowersupplyvariesroughlylinearlywiththeoutputfrequency.2.2MotorStartingwithanExternalMotorThesecondmethodofstartingasynchronousmotoristoattachanexternalstartingmotor(ponymotor)toitandbringthesynchronousmachinetonearaboutitsratedspeed(butnotexactlyequaltoit,asthesynchronizationprocessmayfailtoindicatethepointofclosureofthemainswitchconnectingthesynchronousmachinetothesupplysystem)withtheponymotor.Thentheoutputofthesynchronousmachinecanbesynchronizedorparalleledwithitspowersupplysystemasagenerator,andtheponymotorcanbedetachedfromtheshaftofthemachineorthesupplytotheponymotorcanbedisconnected.OncetheponymotoristurnedOFF,theshaftofthemachineslowsdown,thespeedoftherotormagneticfieldBRfallsbehindBnet,momentarilyandthesynchronousmachinecontinuestooperateasamotor.Assoonasitbeginstooperatesasamotorthesynchronousmotorcanbeloadedintheusualmannerjustlikeanymotor.Thiswholeprocedureisnotascumbersomeasitsounds,sincemanysynchronousmotorsarepartsofmotor-generatorsets,andthesynchronousmachineinthemotor-generatorsetmaybestartedwiththeothermachineservingasthestartingmotor.Moreover,thestartingmotorisrequiredtoovercomeonlythemechanicalinertiaofthesynchronousmachinewithoutanymechanicalload(loadisattachedonlyafterthesynchronousmachineisparalleledtothepowersupplysystem).Sinceonlythemotor’sinertiamustbeovercome,thestartingmotorcanhaveamuchsmallerratingthanthesynchronousmotoritisgoingtostart.Generallymostofthelargesynchronousmotorshavebrushlessexcitationsystemsmountedontheirshafts.Itisthenpossibletousetheseexcitersasthestartingmotors.Formanymedium-sizetolargesynchronousmotors,anexternalstartingmotororstartingbyusingtheexcitermaybetheonlypossiblesolution,becausethepowersystemstheyaretiedtomaynotbeabletohandlethestartingcurrentsneededtousethedamperwinding.Motorfromthedevelopmentsincetheadventofgenerationsofproductsareallaroundthebasicprincipleofthedevelopment,howtorunandmaintainthemainmotoristhemostimportanttaskweare.MotorinChina'seconomicdevelopmentplayavitalrolein,alongwithChina'saccessiontoWTO,theindustryfacedNationalMotorsenormousinternationalcompetitivepressuresandchallengesarebecomingmoreintensified.Tosaveenergyandprotectthelocalenvironment,highefficiencymotoristheinternationaldevelopmenttrend.Itwouldappear,istopromotethehigh-efficiencymotorisnecessary.From：Corpsfrom2005Sichuansynchronousmotorworks同步电动机摘要：近几十年来，随着电力电子技术、微电子技术及现代控制理论的发展，中、小功率电动机在工农业生产及人们的日常生活中都有极其广泛的的应用。特别是在乡镇企业及家用电器中，更需要有大量的中、小功率电动机。由于这种电动机的发展及广泛的应用，它的使用、保养和维护工作也越来越重要，下面就介绍关于同步电动机的相关知识。为了了解一个同步电动机的工作原理，让我们研究这是如何发生的，如果我们连接的电枢绕组（在定子里阐述）是3相同步机合适的平衡3相电源和励磁绕组的D.C适当的电压。目前，通过场线圈流动将替代固定南北磁极,另一方面，3相电流在电枢绕组产生旋转磁场的同步转速旋转流动。换言之在移动中的任何位置定子由于有三相电流，建立南北两极将在一定的时间并即时北极将成为一段时间后1南极期间相应的半周期（经过一段时间=1/2f，其中f=频率的供应）让我们假设，固定南极转子与定子在北极顺时针方向排列正以特定时刻的时间，部队之间定子，转子极-在生产中的吸引力造成的扭矩顺时针方向努力维持这个路线（根据楞次定律）因此转子极试图按定子极作为条件的扭矩顺时针方向生产。不过，转子不能即时移动，由于它的机械惯性，因此需要某个移动来执行。与此同时，定子极会很快（持续时间相应的半周期）改变其极性，成为南极。因此，引力将不再存在，而是像极经历一个斥力，与定子磁极，转子磁极斥力-生产中产生的扭矩在逆时针的方向。生产的扭矩在逆时针的方向。即使是这种情况不会持续作为定子极长将再次改变北极后时间。因此，转子将体验交替的力量，试图提出相应的时间间隔为1秒，顺时针和逆时针的两倍供应，即频率。随着这一期限是非常小的机械相比，转子时间常数，转子无法响应和向任何方向移动。转子继续平稳。相反，如果转子所带来的一些外部手段来接近同步转速说，小马达（称为小马电机可在转导转子）一直流或交流上作为转子，同一轴上的转子磁极被锁定在不同的定子和转子磁极继续运行在同步转速，即使到小马汽车供应中断。因此，同步转子无法启动自身旋转或通常我们说，没有同步转子起动转矩。因此，一些特殊的规定，必须内作出任何机器或机器的外面，使转子提请有关其同步转速附近。当时，如果电枢与电力供应的转子拉入一步，将要继续运转其同步的速度。常用下面描述的方法启动同步电动机。2.同步电动机启动方法基本上有三个用来同步电动机启动方法●要减少定子旋转磁场速度足够低的价值，转子可以轻松地加速并锁定在与它在1个半的旋转磁场的旋转周期。这是通过减少电力的使用频率。这种方法通常遵循的逆变器的情况馈变速驱动下的同步电动机运行的应用程序。●要使用一个外部的主要驱动者，加快同步电机转子附近的同步速度，然后在供应的转子和定子。当然，应采取确保转子的旋转方向，以及这对定子旋转磁场是相同的。这种方法通常是遵循该实验室的同步电机启动发生器和一个连接的应用程序，然后按照同步或平行的程序供应电源。那么电源的主要驱动者被断开，使同步电机将继续作为一个发动机。●要使用阻尼绕组