Reducing of parasitic inductive couplings effects in EMI filters

This paper presents a method to improve EMI filters performances, based on the optimization of the component layout. It´s well known that the EMI filter insertion losses are highly degraded by the high frequency stray couplings between filter passive components. The latter can be reduced by acting on these components´ placement. This paper proposes a method that allow to determine the components´ positions for minimizing the parasitic coupling between them. Their placement is deduced from the study of current distributions and magnetic field induced by these components. This method examines more specifically the parasitic inductive couplings between inductors and capacitors. The choice of the placement that minimizes couplings in 3D is determined to achieve better performance. Some prototypes are realized and characterized to validate the proposed method.