Electric Machinery 电机学 英汉双语 教学课件 作者 刘慧娟 英文课件Chapter3-AC machine Fundamentals.ppt

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1、Chapter3ACMachineFundamentals3.1OperationPrinciplesoftheThree-PhaseSynchronousGenerator3.2ACWindings3.3InducedEMFofACWinding3.4OperationPrinciplesoftheThree-PhaseInductionMotor3.5MMFofACBriefContent3.1OperationPrinciplesoftheThree-PhaseSynchronousGeneratorAsimplifiedtwo-pol

2、edthree-phasesynchronousgeneratorisshown.ThefieldwindingontherotorisexcitedbyaDCvoltage.Thestatorwindingisasetofbalancedthree-phasewindingwithanaxisofeachphasedisplacedby120,andacompletewindingofeachphaseisrepresentedbyasinglecoil,therearesixcoilends,whichareAandX,BandY,Cand

3、Z.Thesecoilsidesareplacedinslotsonthestator.theradialdistributionoftheair-gapfluxdensityBisshown.Astherotorrotates,thefluxwaveformsweepsbythesixcoilsides.TheresultingcoilvoltageisatimefunctionwhichhasthesamewaveformasthespatialdistributionB.Andtherearesixsinusoidalwaveformsof

4、emfareinducedinthesixcoilsidesrespectively,theyhavethesamemagnitude.thespacephasedifferencesbetweentwoadjacentconductorsare60,therefore,theinducedemftimephasedifferencesbetweentwoadjacentconductorsare60,andtheinducedemfphasor-diagramofthesixcoilsidesisshown.Thesetofthree-ph

5、asestatorwindingscanbeconnectedtowye(Y)connectionordelta()connection.Inathree-phasesynchronousgenerator,aDCcurrentisappliedtoarotorwinding,whichwillproducearotormagneticfield.Whentherotorisdrivenbyaprimemoverataconstantspeed,therewillbearotatingmagneticfieldinthemachine.This

6、rotatingmagneticfieldinducesasetofthree-phasevoltageswithinthestatorwindingsofthegenerator.Ifthethree-phasewindingsofthegeneratorareconnectedtothosethreeidenticalloads;therewillbethreesetsofcurrentsflowingthoughthewindingsandtheloads.Eventually,themechanicalpowerfromtheprimem

7、overisconvertedintoanacelectricpowertoloads.3.2ACWindingsACwindingscanbeclassifiedassingle-layerwindingsanddouble-layerwindingsaccordingtothenumberoflayersthatareplacedintheslots.3.2.1Thebasicconceptofacwindings1.Electricalangleetherelationshipbetweentheelectricalangleeandt

8、hemechanicalanglemise=p×m2.CoilsCoilisthebasicelementofthecompone