电气工程及其自动化,专业英语课程论文

重庆邮电大学移通学院《电气工程及其自动化专业英语》课程论文年级2012专业电气工程与自动化姓名孙猜胜学号Three-phaseasynchronousmotorAbstract:Thethree-phaseasynchronousmotorismotor'sonekind.Comparedwithsinglephaseasynchronousmotor,three-phaseasynchronousmotoroperatingperformanceisgood,andcansavevariousmaterials.Hasthestructuretobesimple,themanufactureiseasy,firmdurable,theserviceisconvenient,costinexpensive,dragtheabilityisgood,andsoonaseriesofmerits.thusbecomesineachkindofelectricalmachinerytheoutputtobebiggestutilizesthebroadestonekindofelectricmotor.Keywords:MororMotorstartingStardeltaStartingThree-phaseasynchronousmotorprinciple:Whenthestatorwindingthroughintothethree-phaseacthree-phasesymmetricariseswhenasynchronousspeedn1alongthestatorandrotorroundforspaceinaclockwiserotationmagneticfield.Becauseofarotatingmagneticfieldrotatingspeedton1,rotorconductorofthestaticbeginning,sotherotorconductorwillcutthestatorandproducearotatingmagneticfieldinductionemf(inductionemfdirectionDingZejudgewiththerighthand).Becausethechildisshortcircuitloopendsconductorshortmeet,intheroleoftheinducedemf,willproducetherotorconductorwithinductionemfdirectionbasicconsistentinducedcurrent.Therotorcurrent-carryingconductoratstatormagneticfieldistheroleoftheelectromagneticforce(thedirectionoftheforcewiththelefthandDingZejudge).Theelectromagneticforceoftherotoraxiselectromagnetictorque,drivealongtherotorrotatingmagneticfieldrotationdirection.[1]Throughtheaboveanalysiscanbesummedupthemotorprinciple:whenthethree-phasemotorstatorwinding(eachdiffer120KWHAngle),ventilationwiththree-phaseac,willproducearotatingmagneticfield,therotatingmagneticfieldcuttingrotorwinding,andthustotherotorwindinginducedcurrent(rotorwindingisclosedaccess),loadflowofrotorstatorconductorundertheactionofarotatingmagneticfieldwillproducetheelectromagneticforce,thusinthemotorshaftformedontheelectromagnetictorque,drivingmotorrotation,andmotorrotationdirectionandtherotatingmagneticfieldinthesamedirection.Thestructureofthree-phaseasynchronousmotor:Typesofthree-phaseasynchronousmotor,butallkindsofthree-phaseasynchronousmotoristhesamebasicstructure,theyarethestatorandrotorofthesetwobasiccomponents,thestatorandrotorhasacertainairgapbetween.Inaddition,endcaps,bearings,cableboxes,ringsandotheraccessories,1).StatorpartStatorisusedtogeneratetherotatingmagneticfield.StatorThree-phasemotorsgenerallyshell,statorcore,statorwindingsandotherparts.a.ShellThree-phasemotorcasingincludingbase,endcaps,bearingcaps,rings,suchasjunctionboxesandcomponentsb.StatorCoreInductionmotorstatorcoreispartofthemotorcircuitfrom0.35mm~0.5mmthickcoatedwithathininsulatingpaintfromsilicon,c.ThestatorwindingsThree-phasemotorstatorwindingsarepartofthecircuit,therearethree-phasethree-phasemotorwindings,summetricalthree-phasecurrentaccess,itwillhavearotatingmagneticfield.Three-phasewindingconsistsofthreeseparatecomponentsofthewinding,andeachhasanumberofcoilwindingsconnected.Isaphaseofeachwinding,eachwindinginthespaceangledifferencebetweenthe120°electrical[2].2).Rotorparta.RotorCoreWith0.5mmthicksteelfrom,setintheshaft,theroleandthesamestatorcore,ontheonehand,aspartofthemotormagneticcircuit,ontheonehandtoplacetherotorwindings.b.RotorwindingsTherotorwindinginductionmotorwindingisdividedintotwokindsofcage-shapedandwhichisdividedintowindingrotorasynchronousmotorwithcageinductionmotor.3).OtherpartsofOtherpartsincludingthecover,fans,etc.Inductionmotorstartingmethods:Thereareseveralgeneralmethodsofstartinginductionmotors:fullvoltage,reducedvoltage,wyes-delta,andpartwindingtypes.Thereducedvoltagetypecanincludesolidstatestarters,adjustablefrequencydrives,andautotransformers.Thefollowingisthemostcommonmethod.1).FullvoltageThefullvoltagestartingmethod,alsoknownasacrossthelinestarting,istheeasiestmethodtoemploy,hasthelowestequipmentcosts,andisthemostreliable.Thismethodutilizesacontroltocloseacontactorandapplyfulllinevoltagetothemotorterminals.Thismethodwillallowthemotortogenerateitshigheststartingtorqueandprovidetheshortestaccelerationtimes.Thismethodalsoputsthehigheststrainonthepowersystemduetothehighstartingcurrentsthatcanbetypicallysixtoseventimesthenormalfullloadcurrentofthemotor.2).AutotransformerThemotorleadsareconnectedtothelowervoltagesideofthetransformer.Themostcommontapsthatareusedare80%,65%,and50%.At50%voltagethecurrentontheprimaryis25%ofthefullvoltagelockedrotoramps.Themotorisstartedwiththisreducedvoltage,andthenafterapre-setconditionisreachedtheconnectionisswitchedtolinevoltage.Thisconditioncouldbeapresettime,currentlevel,busvolts,ormotorspeed.Thechangeovercanbedoneineitheraclosedcircuittransition,oranopencircuittransitionmethod.Intheopencircuitmethodtheconnectiontothevoltageisseveredasitischangedfromthereducedvoltagetothelinelevel.Careshouldbeusedtomakesurethattherewillnotbeproblemsfromtransientsduetotheswitching.Thispotentialproblemcanbeeliminatedbyusingtheclosedcircuittransition.WiththeclosedcircuitmethodthereisacontinuousVoltageappliedtothemotor.Anotherbenefitwiththeautotransformerstartingisinpossiblelowervibrationandnoiselevelsduringstarting.3).StardeltaSt