DM and CM Modeling Of Non-Isolated Buck Converters for EMI Filter Design

Abstract

Non-isolated dc-dc converters play an important role in the electrification of automotive, aircraft and shipboard systems. Maximizing the power density/specific power of the EMI filter stage of these converters is critical to achieving the full benefits of electrification. To this end, lean yet accurate models are required. In this paper, a differential-mode/common-mode decomposition and equivalent modeling approach is applied to a non-isolated buck converter topology. Fully decomposed differential-mode and common-mode equivalent models are produced that yield insight into the significantimpact typical asymmetries in the buck converter and its parasitics have on its conducted emissions. A process is outlined for using the equivalent models to design optimal EMI filters for dc-dc converters with respect to system-level objectives.