Three-dimensional parasitics cancellation in EMI filters with Power Sandwich construction

This paper exploits the three-dimensional (3D) parasitics cancellation techniques for EMI filters in Power Sandwich integrated construction. A Power Sandwich filter employs surface mount technology (SMT) compatible x-dimensional (x-dim) components which have the same height and double sided SMT electrical terminations. Thereby a 3D spatial components placement platform is provided. The 3D techniques which aim to canceling/reducing both mutual and self parasitics of the filter are proposed and followed by the experimental verifications. A cancellation turn is designed to reduce the self ESL of the x-dim SMT capacitors. The proposed techniques are applied to a LC CM filter for a motor drive. The filter equivalent circuit model that only includes the extracted components self parasitics is built, where the parasitics and mutual couplings effects are analyzed, the crucial couplings are identified. The techniques are verified through a variety of performed measurements which include both the insertion loss experiments from a network analyzer and spectrum measurements from a LISN in the operating motor drive system. The experimental results show that the proposed techniques significantly improve the filter performance in the high conducted frequency range.