电机学英文文献翻译.docx

电机学英文文献翻译.docx

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电机学英文文献翻译

电机学英文文献翻译

Thethree-phaseinductionmotorspeedcontrolmethod

Three-phaseasynchronousmotorspeedformula:

N=60f/p（1-s）Canbeseenfromtheaboveformula,changethepowersupplyfrequencyf,motorpolenumberpandtheslipsmaybetoomuchtochangethespeedofpurpose.Fromthespeedoftheessenceofview,issimplyadifferentwaytochangespeedsynchronousACmotordoesnotchangethesynctransferspeedortwo.

WidespreaduseinproductionmachineswithoutchangingthesynchronousspeedofmotorspeedcontrolmethodWoundRotorSeriesResistanceSpeed,chopperspeedcontrol,cascadecontrol,andapplicationofelectromagneticslipclutch,fluidcouplings,clutchesandotherfilmspeed.Changethesynchronousspeedofchangeonthenumberofstatorpolemulti-speedmotortochangethestatorvoltageandfrequencytofrequencyconversionwithnochangetothemotorspeedandsoon.

Energyfromthespeedpointofviewwhen,withhighspeedmethodandinefficientmethodsoftwokindsofspeed:

highspeedwhentheslipreferstothesame,sonosliplosses,suchasmulti-speedmotors,Slipfrequencycontrolandlosscanspeedrecoverymethods（suchascascadecontrol,etc.）.Adeterioratinglossofspeedcontrolmethodsareinefficientspeed,suchasseriesresistanceoftherotorspeedmethod,theenergylossintherotorcircuiton;ElectromagneticClutchThespeedmethod,theenergylossintheclutchcoils;fluidcouplingspeed,energylossinthefluidcouplingoftheoil.Generaldeteriorationinlossincreasedwiththeexpansionspeedrange,ifnotspeedrange,theenergylossisminimal.

1,variablespeedcontrolmethodofpolepairs

Thisspeedisthenusedtochangethestatorwindingwaytochangetheredcagemotorstatorpolepairstoachievespeedcontrolpurposes,thefollowingfeaturesWithhardmechanicalproperties,goodstability;

Nosliploss,highefficiency;Wiringsimple,easytocontrol,lowprice;

Alevelspeed,differentiallarge,cannotgetsmoothspeedcontrol;

Withpressureandspeedadjustment,withtheuseofelectromagneticslipclutch,smoothandefficientaccesstohighspeedcharacteristics.

Thismethodissuitablefortheproductiondoesnotrequirevariablespeedmachinery,suchasmetalcuttingmachineBed,Lift,Liftingequipment,FansWaterPumpAndsoon.

2,FrequencyControlMethodFrequencycontrolistochangethemotorstatorPowersupplyFrequency,thuschangingthespeedofitssynchronousspeedmethod.FrequencycontrolsystemmainequipmentistoprovidevariablefrequencypowersupplyInverter,InvertercanbedividedintoAC-DC-ACinverterandAC-ACconvertertwocategories,mostofthecurrentdomesticuseofAC-DC-ACinverter.ItscharacteristicsHigh

efficiency,speedtheprocesswithoutadditionalloss;

Widerangeofapplications,canbeusedforcageinductionmotor;

Speedrange,featuresahard,highaccuracy;

Technicalcomplexity,highcost,difficultmaintenanceandoverhaul.

Thismethodissuitableforthehighaccuracy,goodspeedperformanceoccasions.

3,cascadecontrolmethodCascadecontroliswoundintotherotorcircuitintheseriesofadditionalpotentialcanbeadjustedtochangethemotor'sslip,toachievespeedcontrolpurposes.Mostofthedeteriorationinpowertobeinserieswiththeaddedpotentialabsorbed,re-usegenerateadditionaldevicestoabsorbthedeteriorationinpowertoreturnpowertouseorconversionofenergy.Slip-powerabsorptionunderway,cascadecontrolcanbedividedintoMotorCascadecontrol,mechanicalandthyristorcascadecontrolcascadecontrol,andmulti-usecascadecontrolthyristor,characterizedbyCanspeedtheprocessofdeteriorationinlossoffeedbacktothenetworkorproduction

machinery,moreefficient;

 Installedcapacityandspeedrangeindirectproportiontoinvestment,applicablespeedrange70%-90%ratedspeedofproductionmachinery;

  peeddevicefailurecanswitchtofullspeed,toavoidthecut-off;

Thyristorcascadespeedlowpowerfactor,harmonicsgreaterimpact.

Thismethodissuitableforfans,pumpsandrollingmills,minehoist,extrusionmachines.

4,woundrotormotorspeedcontrolmethodofSeriesResistance

WoundRotorMotoradditionalresistanceinseries,sothatthemotorslipup,motorrunningatlowspeed.Thegreatertheresistanceinseries,themotorspeedislower.Thismethodissimple,easytocontrol,butdeterioratethepowerconsumptionintheformofheatintheresistor.Isaclassspeed,softmechanicalproperties.

5,thestatorpressureandspeedadjustmentmethod

Statorvoltagewhenchangingthemotor,youcangetadifferentsetofmechanicalpropertiesofcurves,whichweredifferentspeeds.Sincethemotortorqueandvoltageproportionaltothesquare,thelargestdeclineinalotoftorque,speedrangeofitssmallcagemotorsingeneralanddifficulttoapply.Inordertoexpandthespeedrange,pressureandspeedadjustmentshouldbelargerrotorresistancevaluecagemotors,suchasdedicatedvoltageregulatorwithspeedtorquemotor,orserieswoundmotorfrequencysensitiveresistors.Inordertoexpandtherangeofstableoperation,whenthespeedof2:

1ormoreoccasionsinthefeedbackcontrolshouldbeadoptedtoachievethepurposeofautomaticadjustmentofspeed.

Pressureandspeedadjustmentisakeydevicetoprovidepowersupplyvoltage,thecurrentwayofatandemcommonsaturationvoltageregulatorReactor,AutoTransformerAndseveralotherThyristorSurge.ThyristorSurgeisthebestway.AdjustingSpeedfeaturesPressureandspeedadjustmentcircuitissimple,easytorealizeautomaticcontrol;

Poorpowersurgeprocesstoheattransferintherotorresistanceintheformofconsumption,lowefficiency.

Pressureandspeedadjustmentgenerallyappliesto100KWbelowproductionmachinery.

6.electromagneticspeedregulatingmotorspeedcontrolmethodofelectromagnetic

speedregulatingelectricmotorsquirrelcagemotor,electricslipclutchandDCexcitationpowersupply（Controller）consistsofthreeparts.DCexcitationpowersmall,usuallyconsistingofsinglephasehalf-waveorfullwaverectifiersthyristorscomposition,changethyristorconductionangle,youcanchangethemagnetizingcurrentsize.

Electromagneticslipclutcharmature,polesandexcitationwindingscomposedofthreeparts.Armatureandthelatterhasnomechanicalcontact,arefreetorotate.Armaturemotorcoaxialconnectionactivepart,drivenbymotors;dockingwiththeloadaxismagneticpolecouplingfromthemovingparts.Whenthearmaturepolesareatrest,suchasexcitationwindingsforDC,alongthecircumferentialsurfacewillformanumberofairgaponthen,s,ofalternatingpolaritypoles,themagneticfluxthroughthearmature.DangelectricarmaturewithdragmotorrotatingShi,duetoelectricarmatureandpolebetweenrelativemovement,andmakeselectricarmatureinductionproducedEddy,thisEddyandmagneticpassmutualroleproducedgomoments,ledhaspoleofrotorbysamedirectionrotating,butitsspeedconstantbelowelectricarmatureofspeedN1,thisisagodifferenceadjustablespeedway,changesgodifferenceclutchdeviceofDCLaimagneticcurrent,willcanchangeclutchdeviceofoutputgomomentsandspeed.Characteristicsofelectromagneticspeedregulatingmotorspeed:

appliances,structureandcontrolcircuitissimple,reliableoperation,easymaintenance;speedandsmooth,steplessspeedregulation

thepowernetworkharmoniceffects;

lostspeed,lowefficiency.

Thismethodappliestomediumandsmallpower,requireslowspeedwhenthesmooth,shortrunproductionmachinery.

7.thehydrauliccouplerspeedregulatinghydraulicCouplerisadeviceforhydraulicdrive,ismadeupofthepumpandturbine,theycollectivelyworkwheels,placedinasealedcase.Shellfilledwithacertainamountofworkingfluid,whenpumpisimpulsedrivenbyrotation,inwhichliquidpropelledbybladeswhichrotate,andundertheactionofcentrifugalforcealongtheouterwheelswhenenteringtheturbinepump,tothrusttotheturbinebladesonthesameturn,makeitdriveproductionmachineryrunning.Powertransfercapacityofthehydrauliccouplerandshellfilledwithfluidvolumesizesareconsistent.Inthecourseofwork,changingthefillingratecanchangethecouplerofturbinespeed,steplessspeedregulation,characterizedby:

powerscope,canmeettheneedsoffromacoupleofdifferentpower10-kilowatttoshuqianqian;

simplestructure,reliableperformance,easytooperationandmaintenance,andlowcost;

smallsize,capacity;

easytoadjust,easytofulfillautomaticcontrol.

Thismethodappliestothespeedofthefanandwaterpump.

三相异步电动机的几种调速方式

三相异步电动机转速公式为：

                         n=60f/p（1-s）

从上式可见，改变供电频率f、电动机的极对数p及转差率s均可太到改变转速的目的。

从调速的本质来看，不同的调速方式无非是改变交流电动机的同步转速或不改变同步转两种。

在生产机械中广泛使用不改变同步转速的调速方法有绕线式电动机的转子串电阻调速、斩波调速、串级调速以及应用电磁转差离合器、液力偶合器、油膜离合器等调速。

改变同步转速的有改变定子极对数的多速电动机，改变定子电压、频率的变频调速有能无换向电动机调速等。

从调速时的能耗观点来看，有高效调速方法与低效调速方法两种：

高效调速指时转差率不变，因此无转差损耗，如多速电动机、变频调速以及能将转差损耗回收的调速方法（如串级调速等）。

有转差损耗的调速方法属低效调速，如转子串电阻调速方法，能量就损耗在转子回路中；电磁离合器的调速方法，能量损耗在离合器线圈中；液力偶合器调速，能量损耗在液力偶合器的油中。

一般来说转差损耗随调速范围扩大而增加，如果调速范围不大，能量损耗是很小的。

一、变极对数调速方法

这种调速方法是用改变定子绕组的接红方式来改变笼型电动机定子极对数达到调速目的，特点如下：

1、具有较硬的机械特性，稳定性良好；

2、无转差损耗，效率高；

3、接线简单、控制方便、价格低；

4、有级调速，级差较大，不能获得平滑调速；

5、可以与调压调速、电磁转差离合器配合使用，获得较高效率的平滑调速特性。

本方法适用于不需要无级调速的生产机械，如金属切削机床、升降机、起重设备、风机、水泵等。

二、变频调速方法

变频调速是改变电动机定子电源的频率，从而改变其同步转速的调速方法。

变频调速系统主要设备是提供变频电源的变频器，变频器可分成交流－直流－交流变频器和交流－交流变频器两大类，目前国内大都使用交－直－交变频器。

其特点：

1、效率高，调速过程中没有附加损耗

2、应用范围广，可用于笼型异步电动机

3、调速范围大，特性硬，精度高

4、技术复杂，造价高，维护检修困难。

本方法适用于要求精度高、调速性能较好场合。

三、串级调速方法

串级调速是指绕线式电动机转子回路中串入可调节的附加电势来改变电动机的转差，达到调速的目的。

大部分转差功率被串入的附加电势所吸收，再利用产生附加的装置，把吸收的转差功率返回电网或转换能量加以利用。

根据转差功率吸收利用方式，串级调速可分为电机串级调速、机械串级调速及晶闸管串级调速形式，多采用晶闸管串级调速，其特点为：

1、可将调速过程中的转差损耗