Characterization of Common/Differential-Mode Behavior in Power Electronic Systems

In this paper, a relatively straightforward approach based upon Thevenin equivalent circuits is considered to model unintended common- and differential-mode (CM and DM) current in multi-converter power electronic-based systems. Thevenin parameters of individual converters are characterized in-situ using an adjustable line impedance stabilization network (LISN). The resulting circuits are then coupled to predict the worst-case CM/DM performance of an aggregate system. The approach enables system-integrators to identify CM/DM coupling, problematic converters, detrimental converter interactions, as well as explore the impact of potential mitigation techniques (EMI filters, alternative grounding strategies, etc.). Hardware experiments are used to validate the strategy.