Investigation of the Near Field Coupling Effects on Common-Mode EMI in Power Converter

In this paper, the effects of near field couplings on common mode noise that exist in Boost PFC converter are modeled and analyzed. It is obvious that these couplings have some effects on CM noise. For electric coupling, effects of parasitic capacitances between PCB traces and heat sink on CM noise is limited since these capacitances is so small compared with the parasitic capacitance between switching device and heat sink. For magnetic couplings, the mutual inductance between Boost inductor and CM noise current loop has no effect on CM noise, and mutual inductance between DM noise loop and CM noise loop will influence the resonant frequency.