Thévenin Equivalent Circuits for Modeling Coupled Common/Differential-Mode Behavior in Power Electronic Systems

Abstract

Modeling the unintended common- and differential-mode (CM and DM) behavior of multi-converter power electronic-based systems can be a challenge. Chief among the issues is the need for detailed knowledge of the converter hardware to determine model parameters. In this paper, a focus is on the derivation of Thévenin-based models that only require characterization at the converter terminals. Periodic linear time varying system analysis is first used to derive and consider the applicability such models. Subsequently, methods to experimentally characterize Thévenin parameters are established. The modeling approach is then used to establish worst-case predictions of CM/DM behavior of a microgrid which is validated using both time-domain simulation and hardware experiment.

Keywords

• Electromagnetic interference (EMI)
• leakage current
• common-mode (CM)
• differential-mode (DM)
• Thévenin equivalent circuit
• micro-grid