Dynamic　inductance　is　an　important　parameter　for　EMI　common　mode　choke　and　has　relationship　with　power　current　bias,　noise　frequency,　core　temperature　and　winding　structures.　Based　on　the　test　results　of　core　material　characteristic　parameter　and　combined　with　the　simulation　analysis　of　the　magnetic　field,　the　magnetic　field　distributions　in　the　core　were　obtained　to　further　build　the　model　of　the　magnetic　field　distribution　in　the　core　by　multiple　nonlinear　regression　algorithms　and　then　the　dynamic　inductance　model　for　the　choke　is　built　considering　the　influences　of　power　current　bias,　noise　frequency　and　core　temperature.　The　model　is　very　useful　to　provide　design　instruction　for　optimization,　volume　reduction　or　noise　suppression　ability　increase　for　common　mode　choke.　The　validity　of　the　model　is　verified　by　experiments.　©　2015　Chinese　Society　for　Electrical　Engineering.