As　power　electronic　power　Converters　move　towards　higher　frequencies,　it　exacerbates　the　electromagnetic　interference　(EMI)　issues　in　power　electronic　Systems.　Accurate　modeling　of　common-mode　chokes　is　crucial　in　designing　EMI　filters　and　predicting　EMI　noise　in　power　Converter　Systems.　However,　existing　models　struggle　to　represent　the　complex　parasitic　parameter　structure　inside　common-mode　chokes　accurately.　It　leads　to　significant　discrepancies　between　the　actual　filtering　characteristics　of　common-mode　chokes　operating　at　high　frequencies　and　their　ideal　designs.　Particularly　concerning　are　the　insertion　loss　characteristics　at　multiple　resonance　points,　where　existing　models　struggle　to　fit　the　multi-resonance　characteristics　of　common-mode　chokes　and　exhibit　entirely　different　insertion　loss　trends　at　high　frequencies.Common-mode　chokes　can　be　divided　into　common-mode　and　differential-mode　components　based　on　the　flow　path　of　their　magnetic　flux.　This　paper　primarily　focuses　on　the　analysis　and　modeling　of　the　differential-mode　component.　The　impedance　testing　method　of　traditional　common-mode　choke　differential-mode　models　does　not　comply　with　the　EN55017　testing　Standard.　The　main　difference　is　that　traditional　impedance　testing　typically　involves　shorting　one　port　of　the　common-mode　choke　to　measure　the　differential-mode　component.　However,　shorting　the　port　alters　the　actual　path　of　the　differential-mode　current,　thereby　failing　to　accurately　characterize　the　complete　inter-winding　capacitance　distribution　of　common-mode　chokes,　resulting　in　different　trends　between　the　two　testing　methods　above　10　MHz.　Additionally,　the　traditional　common-mode　choke　differential-mode　model　assumes　ideal　inductance.　However,　when　connected　in　series　with　the　common-mode　component　at　high　frequencies,　this　idealization　alters　the　filtering　characteristics　of　the　model＇s　common-mode　component.　Therefore,　the　proposed　differential-mode　model　should　not　exhibit　a　counteracting　effect　on　common-mode　current.Firstly,　by　analyzing　the　electromagnetic　field　distribution　inside　common-mode　chokes,　a　new　high-frequency　model　is　proposed.　This　new　model,　when　considering　inter-winding　capacitance,　divides　the　inductance　of　the　differential-mode　component　of　one　winding　into　two　equal　parts　based　on　existing　terminal　capacitance.　Furthermore,　a　new　inter-winding　parasitic　capacitance　branch　is　added　between　the　two　parts　of　the　inductance,　in　conjunction　with　the　existing　terminal　capacitance　branch,　to　simulate　the　complete　inter-winding　electric　field　characteristics.　Setting　the　differential-mode　inductance　as　a　coupled　inductance　with　a　coupling　coefficient　of　-1　can　fully　counteract　its　influence　on　the　common-mode　component.　This　proposed　model　accurately　fits　the　insertion　loss　characteristics　of　the　differential-mode　component　of　common-mode　chokes　under　the　EN55017　testing　standard＇s　multiple　resonance　points.　Secondly,　an　equivalent　circuit　model　is　established　under　different　insertion　loss　tests.　Utilizing　principles　such　as　star-to-delta　transformation　and　the　Wheatstone　bridge　balance　principle,　the　equivalent　circuit　is　simplified,　and　circuit　expressions　are　derived.　Then,　a　comprehensive　process　for　extracting　parasitic　parameters　within　the　new　model　is　proposed.Experimental　conclusions　are　as　follows.　(1)　Setting　the　inductance　model　of　the　differential-mode　component　as　a　coupled　inductance　with　k=—\　does　not　attenuate　common-mode　current.　(2)　Compared　with　traditional　models,　the　proposed　new　model　exhibits　good　fitting　accuracy　within　the　frequency　ränge　of　150　kHz　to　30　MHz　and　effectively　represents　the　multi-resonance　characteristics　of　common-mode　chokes.　©　2025　China　Machine　Press.　All　rights　reserved.