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

Abstract

Capacitor parasitic inductance often limits the high-frequency performance of electromagnetic interference (EMI) filters in both common-mode (CM) and differential-mode (DM) 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 DM and CM 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