Inductance Compensation of Multiple Capacitors with Application to Common- and Differential-Mode Filters

Capacitor parasitic inductance often limits the high-frequency performance of Electromagnetic Interference (EMI) filters in both common- and differential-mode filtering domains. However, these limitations can be overcome through the use of specially-coupled magnetic windings that effectively nullify the capacitor parasitic inductance. This document explores the use of a single coupled magnetic winding to provide inductance compensation for multiple capacitors (e.g. both differential- and common-mode capacitors) simultaneously, reducing the number of coils previously required. The substantial advantages of this method are illustrated both in a proof-of-concept test circuit and in an improved version of an existing EMI filter. The coupling between multiple inductance compensation windings in a single filter enclosure is also investigated.