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1、.word格式,ACMachinesIntroductionTheelectricalmachinethatconvertselectricalenergyintomechanicalenergy,andviceversa,istheworkhorseinadrivesystem.Amachineisacomplexstructureelectrically,mechanically,andthermally.Althoughmachineswereintroducedmorethanonehundredyearsago,there
2、searchanddevelopmentinthisareaappearstobenever-ending.However,theevolutionofmachineshasbeenslowcomparedtothatofpowersemiconductordevicesandpowerelectronicconverters.Traditionally,ACmachineswithaconstantfrequencysinusoidalpowersupplyhavebeenusedinconstant-speedapplicati
3、ons,whereasDCmachineswerepreferredforvariable-speeddrives.Butinthelasttwoorthreedecades,wehaveseenextensiveresearchanddevelopmenteffortsforvariable-frequency,variable-speedACmachinedrivetechnology,andtheywillprogressivelyreplaceDCdrives.Inmostcases,newapplicationsuseAC
4、drives.ACmachinescangenerallybeclassifiedasfollows:Inductionmachines:Cageorwoundrotor(doubly-fed),Rotatingorlinear;Synchronousmachines:Rotatingorlinear,Reluctance,Woundfieldorpermanentmagnet,Radialoraxialgap(disk),Surfacemagnetorinterior(buried)magnet,Sinusoidalortrape
5、zoidal;Variablereluctancemachines:Switchedreluctance,Stepper.InductionMachinesAmongalltypesofACmachines,theinductionmachine,particularlythecagetype,ismostcommonlyusedinindustry.Thesemachinesareveryeconomical,rugged,andreliable,andareavailableintherangesoffractionalhors
6、epower(FHP)tomulti-megawattcapacity.Low-powerFHPmachinesareavailableinsingle-phase,butpoly-phase(three-phase)machinesareused,mostofteninvariable-speeddrives.Fig.1-6A-1showsanidealizedthree-phase,two-poleinductionmotorwhereeachphasewindinginthestatorandrotorisrepresente
7、dbyaconcentratedcoil.Thethree-phasewindingsaredistributedsinusoidallyandembeddedinslots.Inawound-rotormachine,therotorwindingissimilartothatofthestator,butinacagemachine,therotorhasasquirrelcage-likestructurewith,专业.专注..word格式,shortedendrings.Basically,themachinecanbel
8、ookeduponasathree-phasetransformerwitharotatingandshort-circuitedsecondary.Bothstatorandrotorcoresaremadewithlaminate
