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ID:59180468
大小:1.03 MB
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时间:2020-09-26
《电磁场与电磁波第14讲边界条件电感磁能ppt课件.ppt》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、FieldandWaveElectromagnetic电磁场与电磁波第14讲1作业情况1班:人合计:人情况:23porpor41.TheMagneticDipole2.MagnetizationandEquivalentCurrentDensitiesReview53.MagneticFieldIntensityandRelativePermeabilityDifferentialformIntegralformPostulatesofMagnetostaticsinmagneticmaterial6MaintopicSteadyM
2、agneticFields1.BoundaryConditionsforMagnetostaticFields2.InductancesandInductors3.MagneticEnergy71.BoundaryConditionsforMagnetostaticFields12B2H1B1H2an2Js8E2E121atwhacdban2hS21an2D1D2s9(a)Thenormalcomponentsofthemagneticfluxdensityarecontinuousacrossaninterf
3、ace.Forlinearisotropicmedia,wehave(b)ThetangentialcomponentoftheHfieldisdiscontinuousacrossaninterfacewhereafreesurfacecurrentexistsThetangentialcomponentofHiscontinuous(连续)acrosstheboundaryofalmostallphysicalmedia;itisdiscontinuous(不连续)onlywhenaninterfacewithanidealpe
4、rfectconductor(理想导体)orasuperconductor(超导体)isassumed.10Example1.AloopmagneticcorewithagapiscloselywoundbyacoilwithNturns,asshowninthefigure.WhenthecoilcarriesacurrentI,andtheleakagemagneticfluxoutsidethecoilisneglected,findthemagneticfluxdensityandthemagneticfieldintens
5、ityinthecoreandthegap.Solution:Sincetheleakagemagneticfluxisneglected,thedirectionofthemagneticfluxdensityisaroundthecircle,anditisperpendiculartotheendfacesofthegap.Fromtheboundarycondition,weknowthatthemagneticfluxdensityBginthegapisequaltoBfinthecore,i.e.11Sincer0>>
6、a,themagneticfieldinthecorecanbeconsideredtobeuniform.UsingAmpere’scircuitallawinmedia,andtakingthecircleofradiusr0astheintegralpath,thenwehaveConsidering,wehaveThenInthegapInthecore128.BoundaryConditionsforMagnetostaticFields132.InductancesandInductorsMutualflux12(互磁
7、通)Faraday’slawofelectromagneticinductionBiot-SavartlawwheretheproportionalityconstantL12iscalledthemutualinductance(互感)betweenloopsC1andC2,withtheunithenry(H).IncaseC2hasN2turns,thefluxlinkage12(磁链数)dueto1214Themutualinductance(互感)betweentwocircuitsisthenthemagneticf
8、luxlinkage(磁链数)withonecircuitperunitcurrent(单位电流)intheother.Itapplyonlytolinearmedia(线性媒质).AmoregeneraldefinitionforL
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