电磁兼容资料第二部分6

1HFCurrentDistributionintoWindingsInductor:singlewinding............++++++++++++lgFlFHFHgg=llFH=Currenttendstoflowintowindinginnersurface2HFCurrentDistributionintoWindingsSingle-layertransformerPrimary:4turns-3ASecondary:1turn-12A....................++++++++++++FF+.+++++++++++...Themagneticfieldtendstocancelintheregionsoutsideandinsidebothwindingsbutnotbetweenthetwowindings3LFCurrentDistributionintoWindingsMulti-layertransformerThecurrentishomogeneouslydistributedinsideconductorsP1P2S3S2S1F=NIEnergydensity[J/m3]∝W[J]4LFCurrentDistributionintoWindingsInterleavedmulti-layertransformerPaPbSbSaF=NIEnergydensity[J/m3]∝W[J]Reducedleakageinductance5HFCurrentDistributionintoWindingsMagneticfieldexistsonlybetweenwindinglayersduetoskindepthMulti-layertransformerF=NIP2P1S3S2S1Skindepthf10σπµ=δ6HFCurrentDistributionintoWindingsSecondarycurrent:1AMagneticfieldexistsonlybetweenwindinglayers:differentcurrentsareinducedintowindinglayersurfaces++1.-1+++2..-2++++3I=F=NISkindepthf10σπµ=δS3S2S17HFCurrentDistributionintoWindingsF=NIS3S2S1+...++++++1-1+2-2+3I=2DCDCIRP=()()2AC2AC2ACACIR13I2RI3RP3S=−+=()()2AC2AC2ACACIR5IRI2RP2S=−+=()2ACACIRP1S=Low-frequencypowerloss:High-frequencypowerloss:2ACACACACACIR3193PPPP1S2S3SAVG=++=8HFEffectintoPassiveLayersLayernotcarryinganetcurrent(oneprimarywindinginpush-pulltransformers,onesecondarywindingincenter-tappedtransformer,EMIshielding)F=NIS3S2S1+...++++++1-1+2-2+3I=+++...-3+3PHighlosses!9HFEffectinParalleledWindingsSeparatedprimary-secondarywindingsPS..+......+++++++Currentdistributesonlyontoinnersurfaceofinnerlayerswheremagneticfieldismaximum(Energyminimization)10HFEffectinParalleledWindingsInterleavedprimary-secondarywindingsPS........++++++++Goodcurrentsplitting11HFWindingResistanceDowellcurves(sinusoidalexcitation)==turnseparation,Dw=conductordiameter