负载变压器与直流电机外文文献翻译

负载变压器与直流电机外文文献翻译(含：英文原文及中文译文)文献出处：BMirafzal.TheTransformeronload﹠IntroductiontoDCMachines[J].JournalofMaterialsProcessingTechnology,2013,2(3):112-118.英文原文TheTransformeronload﹠IntroductiontoDCMachinesBMirafzalIthasbeenshownthataprimaryinputvoltage1Vcanbetransformedtoanydesiredopen-circuitsecondaryvoltage2Ebyasuitablechoiceofturnsratio.2Eisavailableforcirculatingaloadcurrentimpedance.Forthemoment,alaggingpowerfactorwillbeconsidered.Thesecondarycurrentandtheresultingampere-turns22NIwillchangetheflux,tendingtodemagnetizethecore,reducemΦandwithit1E.Becausetheprimaryleakageimpedancedropissolow,asmallalterationto1Ewillcauseanappreciableincreaseofprimarycurrentfrom0Itoanewvalueof1Iequalto()()ijXREV++111/.Theextraprimarycurrentandampere-turnsnearlycancelthewholeofthesecondaryampere-turns.Thisbeingso,themutualfluxsuffersonlyaslightmodificationandrequirespracticallythesamenetampere-turns10NIasonnoload.Thetotalprimaryampere-turnsareincreasedbyanamount22NInecessarytoneutralizethesameamountofsecondaryampere-turns.Inthevectorequation,102211NININI=+;alternatively,221011NININI-=.Atfullload,thecurrent0Iisonlyabout5%ofthefull-loadcurrentandso1Iisnearlyequalto122/NNI.Becauseinmindthat2121/NNEE=,theinput2kVAwhichisapproximately11IEisalsoapproximatelyequaltotheoutputkVA,22IE.Thephysicalcurrenthasincreased,andwithintheprimaryleakagefluxtowhichitisproportional.Thetotalfluxlinkingtheprimary,111Φ=Φ+Φ=Φmp,isshownunchangedbecausethetotalbacke.m.f.,(dtdNE/111Φ-)isstillequalandoppositeto1V.However,therehasbeenaredistributionoffluxandthemutualcomponenthasfallenduetotheincreaseof1Φwith1I.Althoughthechangeissmall,thesecondarydemandcouldnotbemetwithoutamutualfluxande.m.f.alterationtopermitprimarycurrenttochange.ThenetfluxsΦlinkingthesecondarywindinghasbeenfurtherreducedbytheestablishmentofsecondaryleakagefluxdueto2I,andthisopposesmΦ.AlthoughmΦand2Φareindicatedseparately,theycombinetooneresultantinthecorewhichwillbedownwardsattheinstantshown.ThusthesecondaryterminalvoltageisreducedtodtdNVS/22Φ-=whichcanbeconsideredintwocomponents,i.e.dtdNdtdNVm//2222Φ-Φ-=orvectorially2222IjXEV-=.Asfortheprimary,2Φisresponsibleforasubstantiallyconstantsecondaryleakageinductance222222/Λ=ΦNiN.Itwillbenoticedthattheprimaryleakagefluxisresponsibleforpartofthechangeinthesecondaryterminalvoltageduetoitseffectsonthemutualflux.Thetwoleakagefluxesarecloselyrelated;2Φ,forexample,byitsdemagnetizingactiononmΦhascausedthechangesontheprimarysidewhichledtotheestablishmentofprimaryleakageflux.Ifalowenoughleadingpowerfactorisconsidered,thetotalsecondaryfluxandthemutualfluxareincreasedcausingthesecondaryterminalvoltagetorisewithload.pΦisunchangedinmagnitudefromthenoloadconditionsince,neglectingresistance,itstillhastoprovideatotalbacke.m.f.equalto1V.Itisvirtuallythesameas11Φ,thoughnowproducedbythecombinedeffectofprimaryandsecondaryampere-turns.Themutualfluxmuststillchangewithloadtogiveachangeof1Eandpermitmoreprimarycurrenttoflow.1Ehasincreasedthistimebutduetothevectorcombinationwith1Vthereisstillanincreaseofprimarycurrent.Twomorepointsshouldbemadeaboutthefigures.Firstly,aunityturnsratiohasbeenassumedforconveniencesothat'21EE=.Secondly,thephysicalpictureisdrawnforadifferentinstantoftimefromthevectordiagramswhichshow0=Φm,ifthehorizontalaxisistakenasusual,tobethezerotimereference.Thereareinstantsinthecyclewhen3primaryleakagefluxiszero,whenthesecondaryleakagefluxiszero,andwhenprimaryandsecondaryleakagefluxiszero,andwhenprimaryandsecondaryleakagefluxesareinthesamesense.Theequivalentcircuitalreadyderivedforthetransformerwiththesecondaryterminalsopen,caneasilybeextendedtocovertheloadedsecondarybytheadditionofthesecondaryresistanceandleakagereactance.Practicallyalltransformershaveaturnsratiodifferentfromunityalthoughsuchanarrangementissometimesemployedforthepurposesofelectricallyisolatingonecircuitfromanotheroperatingatthesamevoltage.Toexplainthecasewhere21NN≠thereactionofthesecondarywillbeviewedfromtheprimarywinding.Thereactionisexperiencedonlyintermsofthemagnetizingforceduetothesecondaryampere-turns.Thereisnowayofdetectingfromtheprimarysidewhether2Iislargeand2Nsmallorviceversa,itistheproductofcurrentandturnswhichcausesthereaction.Consequently,asecondarywindingcanbereplacedbyanynumberofdifferentequivalentwindingsandloadcircuitswhichwillgiverisetoanidenticalreactionontheprimary.Itisclearlyconvenienttochangethesecondarywindingtoanequivalentwindinghavingthesamenumberofturns1Nastheprimary.Thereareafewcheckswhichcanbemadetoseeiftheprocedureoutlinedisvalid.Forexample,thecopperlossinthereferredsecondarywindingmustbethesameasintheoriginalsecondaryotherwisetheprimarywouldhavetosupplyadifferentlosspower.Theargumentissound,thoughatfirstitmayhaveseemedsuspect.Infact,iftheactualsecondarywindingwasremovedphysicallyfromthecoreandreplacedbytheequivalentwindingandloadcircuitdesignedtogivetheparameters1N,'2R,'2Xand'2I,measurementsfromtheprimaryterminalswouldbeunabletodetectanydifferenceinsecondaryampere-turns,kVAdemandorcopperloss,undernormalpowerfrequencyoperation.Theequivalentcircuitforthegeneralcasewhere21NN≠exceptthatmrhasbeenaddedtoallowforironlossandanideallosslesstransformationhasbeenincludedbeforethesecondaryterminalstoreturn'2Vto2V.Allcalculationsofinternalvoltageandpowerlossesaremadebeforethisidealtransformationisapplied.Thebehaviourofatransformerasdetectedatbothsetsofterminalsisthesameasthebehaviourdetectedatthecorrespondingterminalsofthiscircuitwhentheappropriateparametersareinserted.Theslightlydifferentrepresentationshowingthecoils1Nand2Nsidebysidewithacoreinbetweenisonlyusedforconvenience.Onthetransformeritself,thecoilsare,ofcourse,woundroundthesamecore.Itshouldbepointedoutthattheequivalentcircuitasderivedhereisonlyvalidfornormaloperationatpowerfrequencies;capacitanceeffectsmustbetakenintoaccountwhenevertherateofchangeofvoltagewouldgiverisetoappreciablecapacitancecurrents,dtCdVIc/=.Theyareimportantathighvoltagesandatfrequenciesmuchbeyond100cycles/sec.Afurtherpointisnottheonlypossibleequivalentcircuitevenforpowerfrequencies.Analternative,treatingthetransformerasathree-orfour-terminalnetwork,givesrisetoarepresentationwhichisjustasaccurateandhassomeadvantagesforthecircuitengineerwhotreatsalldevicesascircuitelementswithcertaintransferproperties.Thecircuitonthisbasiswouldhaveaturnsratiohavingaphaseshiftaswellasamagnitudechange,andtheimpedanceswouldnotbethesameasthoseofthewindings.Thecircuitwouldnotexplainthephenomenawithinthedeviceliketheeffectsofsaturation,soforanunderstandingofinternalbehaviour.Therearetwowaysoflookingattheequivalentcircuit:(a)viewedfromtheprimaryasasinkbutthereferredloadimpedanceconnectedacross'2V,or(b)viewedfromthesecondaryasasourceofconstantvoltage1Vwithinternaldropsdueto1Reand1Xe.Themagnetizingbranchissometimesomittedinthisrepresentationandsothecircuitreducestoageneratorproducingaconstantvoltage1E(actuallyequalto1V)andhavinganinternalimpedancejXR+(actuallyequalto11RejXe+).Ineithercase,theparameterscouldbereferredtothesecondarywindingandthismaysavecalculationtime.Theresistancesandreactancescanbeobtainedfromtwosimplelightloadtests.IntroductiontoDCMachinesDCmachinesarecharacterizedbytheirversatility.Bymeansofvariouscombinationofshunt,series,andseparatelyexcitedfieldwindingstheycanbedesignedtodisplayawidevarietyofvolt-ampereorspeed-torquecharacteristicsforbothdynamicandsteadystateoperation.Becauseoftheeasewithwhichtheycanbecontrolled,systemsofDCmachinesareoftenusedinapplicationsrequiringawiderangeofmotorspeedsorprecisecontrolofmotoroutput.TheessentialfeaturesofaDCmachineareshownschematically.Thestatorhas6salientpolesandisexcitedbyoneormorefieldcoils.Theair-gapfluxdistributioncreatedbythefieldwindingissymmetricalaboutthecenterlineofthefieldpoles.Thisaxisiscalledthefieldaxisordirectaxis.Asweknow,theACvoltagegeneratedineachrotatingarmaturecoilisconvertedtoDCintheexternalarmatureterminalsbymeansofarotatingcommutatorandstationarybrushestowhichthearmatureleadsareconnected.Thecommutator-brushcombinationformsamechanicalrectifier,resultinginaDCarmaturevoltageaswellasanarmaturem.m.f.wavewhichisfixedinspace.Thebrushesarelocatedsothatcommutationoccurswhenthecoilsidesareintheneutralzone,midwaybetweenthefieldpoles.Theaxisofthearmaturem.m.f.wavethenin90electricaldegreesfromtheaxisofthefieldpoles,i.e.,inthequadratureaxis.Intheschematicrepresentationthebrushesareshowninquaratureaxisbecausethisisthepositionofthecoilstowhichtheyareconnected.Thearmaturem.m.f.wavethenisalongthebrushaxisasshown..(Thegeometricalpositionofthebrushesinanactualmachineisapproximately90electricaldegreesfromtheirpositionintheschematicdiagrambecauseoftheshapeoftheendconnectionstothecommutator.)Themagnetictorqueandthespeedvoltageappearingatthebrushesareindependentofthespatialwaveformofthefluxdistribution;forconvenienceweshallcontinuetoassumeasinusoidalflux-densitywaveintheairgap.Thetorquecanthenbefoundfromthemagneticfieldviewpoint.Thetorquecanbeexpressedintermsoftheinteractionofthedirect-axisair-gapfluxperpoledΦandthespace-fundamentalcomponent1aFofthearmaturem.m.f.wave.Withthebrushesinthequadratureaxis,theanglebetweenthesefieldsis90electricaldegrees,anditssineequalsunity.ForaPpolemachine12)2(2adFPTϕπ=Therectifiedvoltagegeneratedinthearmaturehasalreadybeendiscussedbeforeforanelementarysingle-coilarmature.Theeffectofdistributingthewindinginseveralslotsisshowninfigure,inwhicheachoftherectifiedsinewavesisthevoltagegeneratedinoneofthecoils,commutationtakingplaceatthemomentwhenthecoilsidesareintheneutralzone.Thegeneratedvoltageasobservedfromthebrushesisthesumoftherectifiedvoltagesofallthecoilsinseriesbetweenbrushesandisshownbytheripplinglinelabeledaeinfigure.Withadozenorsocommutatorsegmentsperpole,theripplebecomesverysmallandtheaveragegeneratedvoltageobservedfromthebrushesequalsthesumoftheaveragevaluesoftherectifiedcoilvoltages.Therectifiedvoltageaebetweenbrushes,knownalsoasthespeedvoltage,ismdamdaaWKWmPCeϕϕπ==2WhereaKisthedesignconstant.Therectifiedvoltageofadistributedwindinghasthesameaveragevalueasthatofaconcentratedcoil.Thedifferenceisthattherippleisgreatlyreduced.Overafairlywiderangeofexcitationthereluctanceoftheironisnegligiblecomparedwiththatoftheairgap.Inthisregionthefluxislinearlyproportionaltothetotalm.m.f.ofthefieldwindings,theconstantofproportionalitybeingthedirect-axisair-gappermeance.TheoutstandingadvantagesofDCmachinesarisefromthewidevarietyofoperatingcharacteristicswhichcanbeobtainedbyselectionofthemethodofexcitationofthefieldwindings.ThefieldwindingsmaybeseparatelyexcitedfromanexternalDCsource,ortheymaybeself-excited;i.e.,themachinemaysupplyitsownexcitation.Themethodofexcitationprofoundlyinfluencesnotonlythesteady-statecharacteristics,butalsothedynamicbehaviorofthemachineincontrolsystems.Theconnectiondiagramofaseparatelyexcitedgeneratorisgiven.Therequiredfieldcurrentisaverysmallfractionoftheratedarmaturecurrent.Asmallamountofpowerinthefieldcircuitmaycontrolarelativelylargeamountofpowerinthearmaturecircuit;i.e.,thegeneratorisapoweramplifier.Separatelyexcitedgeneratorsareoftenusedinfeedbackcontrolsystemswhencontrolofthearmaturevoltageoverawiderangeisrequired.Thefieldwindingsofself-excitedgeneratorsmaybesuppliedinthreedifferentways.Thefieldmaybeconnectedinserieswiththearmature,resultinginashuntgenerator,orthefieldmaybeintwosections,oneofwhichisconnectedinseriesandtheotherinshuntwiththearmature,resultinginacompoundgenerator.Withself-excitedgeneratorsresidualmagnetismmustbepresentinthemachineirontogettheself-excitationprocessstarted.Inshuntandseparatelyexcitedmotorsthefieldfluxisnearlyconstant.Consequently,increasedtorquemustbeaccompaniedbyaverynearlyproportionalincreaseinarmaturecurrentandhencebyasmalldecreaseincountere.m.f.toallowthisincreasedcurrentthroughthesmallarmatureresistance.Sincecountere.m.f.isdeterminedbyfluxandspeed,thespeedmustdropslightly.Likethesquirrel-cageinductionmotor,theshuntmotorissubstantiallyaconstant-speedmotorhavingabout5percentdropinspeedfromnoloadtofullload.Startingtorqueandmaximumtorquearelimitedbythearmaturecurrentthatcanbecommutatedsuccessfully.Anoutstandingadvantageoftheshuntmotoriseaseofspeedcontrol.Witharheostatintheshunt-fieldcircuit,thefieldcurrentandfluxperpolecanbevariedatwill,andvariationoffluxcausestheinversevariationofspeedtomaintaincountere.m.f.Intheseriesmotor,increaseinloadisaccompaniedbyincreaseinthearmaturecurrentandm.m.f.andthestatorfieldflux(providedtheironisnotcompletelysaturated).Becausefluxincreaseswithload,speedmustdropinordertomaintainthebalancebetweenimpressedvoltageandcountere.m.f.;moreover,theincreaseinarmaturecurrentcausedbyincreasedtorqueissmallerthanintheshuntmotorbecauseoftheincreasedflux.Theseriesmotoristhereforeavarying-speedmotorwithamarkedlydroopingspeed-loadcharacteristic.Forapplicationsrequiringheavytorqueoverloads,thischaracteristicisparticularlyadvantageousbecausethecorrespondingpoweroverloadsareheldtomorereasonablevaluesbytheassociatedspeeddrops.Veryfavorablestartingcharacteristicsalsoresultfromtheincreaseinfluxwithincreasedarmaturecurrent.Inthecompoundmotortheseriesfieldmaybeconnectedeithercumulatively,sothatits.m.m.f.addstothatoftheshuntfield,ordifferentially,sothatitopposes.Thedifferentialconnectionisveryrarelyused.Acumulativelycompoundedmotorhasspeed-loadcharacteristicintermediatebetweenthoseofashuntandaseriesmotor,thedropofspeedwithloaddependingontherelativenumberofampere-turnsintheshuntandseriesfields.Itdoesnothavethedisadvantageofveryhighlight-loadspeedassociatedwithaseriesmotor,butitretainstoaconsiderabledegreetheadvantagesofseriesexcitation.TheapplicationadvantagesofDCmachineslieinthevarietyofperformancecharacteristicsofferedbythepossibilitiesofshunt,series,andcompoundexcitation.Someofthesecharacteristicshavebeentoucheduponbrieflyinthisarticle.Stillgreaterpossibilitiesexistifadditionalsetsofbrushesareaddedsothatothervoltagescanbeobtainedfromthecommentator.ThustheversatilityofDCmachinesystemsandtheiradaptabilitytocontrol,bothmanualandautomatic,aretheiroutstandingfeatures.中文译文负载变压器和直流电机介绍BMirafzal研究已经表明，通过适当选择匝数比，主输入电压1V可以变换为任何期望的开路次级电压2E。2E可用于循环负载电流阻抗。目前，将考虑滞后功率因数。次级电流和所产生的安匝数22NI将改变磁通量，倾向于去磁芯，减小mΦ并与1E一起。因为初级泄漏阻抗下降很小，所以1E的小改动将导致初级电流从0I明显增加到1I的新值，等于（）（）ijXREV++111/。额外的初级电流和安培匝数几乎消除了整个次级安培-转数。这样，相互通量只受到轻微的修改，并且实际上需要与无负载时相同的净安匝数10NI。为了中和相同数量的二次安培匝数，总的主安匝数增加了22N。在向量方程中，102211NININI=+;或者，221011N我N我N-=。在满载情况下，电流0I仅为满载电流的5％左右，因此1I几乎等于122/NNI。因为考虑到2121/NNEE=，输入2kVA约为11IE也近似等于输出kVA，22IE。物理电流增加了，并且与其成正比的初级漏磁通量也增加了。连接初级111φ=Φ+Φ=Φmp的总磁通量表示为不变，因为总的后电流fm，（dtdNE/111Φ-）仍然与1V相等并相反。然而，由于1I增加1Φ，磁通重新分配，相互成分下降。虽然变化很小，但如果没有相互交流和e.m.f.，二次需求就无法实现。改变以允许原电流改变。通过建立由2I引起的次级漏磁通量，进一步减小了与次级绕组相连的净磁通量φ，这与mΦ相反。尽管mΦ和2Φ分别表示，但它们在核心中结合成一个结果，在所示瞬间向下结果。因此，次级终端电压降为dtdNVS/22Φ-=这可以考虑为两个分量，即dtdNdtdNVm//2222Φ-Φ-=或者矢量2222IjXEV-=。对于初级，2Φ负责基本不变的次级漏感222222/Λ=ΦNiN。将会注意到，由于其对相互通量的影响，初级漏磁通量负责次级端电压的部分变化。两种泄漏通量密切相关;2Φ，例如，由于它对mΦ的消磁作用，导致初级侧的变化导致初级漏磁通的建立。如果考虑到足够低的前导功率因数，则总次级磁通量和相互磁通量增加，导致次级端电压随着负载而升高。ΦΦ在空载条件下的量值不变，因为忽略电阻，它仍然必须提供总后向电流。等于1V。它与11Φ几乎相同，但现在由主安培和次安培的组合效应产生。相互通量仍然必须随着负载而改变，以改变1E并允许更多的初级电流流动。1E这次增加了，但由于与1V的向量组合，初级电流仍然增加。应该对这些数字再提两点。首先，为了方便已经假设了单位圈数比，以便'21EE=。其次，如果横轴取平常值，则从显示0=Φm的矢量图中绘制物理图片的不同时刻，作为零时间参考。当三次漏磁通为零，二次漏磁通为零时，以及一次漏磁通量为零时，以及一次漏磁通量与次漏磁通量具有相同意义时，循环中有时刻。已经为次级终端打开的变压器推导出的等效电路可以很容易地扩展到通过增加次级电阻和漏电抗来覆盖负载次级。实际上所有的变压器都具有不同于1的匝数比，尽管这样的布置有时被用于将一个电路与另一个电路在相同电压下操作的电路隔离。为了解释21NN≠次级反应的情况，将从初级绕组来看。仅由于次级安匝所引起的磁化力而经历反应。从初级侧无法检测到2I是大还是小2N，反之亦然，它是电流和匝数的产物，引起反应。因此，次级绕组可以被任何数量的不同的等效绕组和负载电路所替代，这将在初级绕组上产生相同的反应。将次级绕组改变为具有相同匝数1N的等效绕组显然是方便的作为主要的。有几项检查可以查看所列程序是否有效。例如，所提及的次级绕组中的铜损必须与原始次级中的铜损相同，否则主要将不得不提供不同的损耗功率。这个论点很有道理，尽管起初它似乎有些可疑。事实上，如果实际的次级绕组从物理上被移除并且被设计为给出参数1N，'2R，'2X和'2I的等效绕组和负载电路代替，则来自主要端子的测量结果将不能检测到在正常工频操作下二次安培匝数，千伏安需求或铜损的差异。对于21NN≠除mr之外的一般情况，添加了允许铁损和理想无损变换的一般情况的等效电路已包含在次级端子之前，以使2V返回到2V。所有内部电压和功率损耗的计算均为在应用这种理想转换之前做出的。在两组端子处检测到的变压器的行为与在插入适当参数时在该电路的相应端子处检测到的行为相同。示出线圈1N和2N并排地具有中心之间的稍微不同的表示仅用于方便。在变压器本身上，线圈当然缠绕在同一个铁芯上。应该指出，这里推导出的等效电路仅适用于工频正常工作;只要电压的变化率会引起可观的电容电流，就必须考虑电容效应，dtCdVIc/=。它们在高电压和频率超过100次/秒时非常重要。另一点并不是唯一可能的等效电路，即使对于电力频率也是如此。另一种方法是将变压器视为三端或四端网络，产生的表示同样准确，并且对于电路工程师来说具有某些优点将所有设备视为具有某些传输属性的电路元件。在此基础上的电路将具有具有相移以及幅度变化的匝数比，并且阻抗不会与绕组的相同。该电路不会像饱和度的影响那样解释器件内部的现象，因此了解内部行为。有两种方法查看等效电路：（a）从主电源看为接收器，但所提到的负载阻抗连接在2V或2V之间（b）从次级视角看，1V和1Xe引起的内部压降为1V的恒定电压源。在这种表示中有时省略了磁化支路，因此电路减少到产生恒定电压1E（实际上等于1V）并且具有内部阻抗jXR+（实际上等于11RejXe+）的发生器。无论哪种情况，参数都可以被称为次级绕组，这可以节省计算时间。电阻和电