Differential-mode EMI emission prediction of SiC-based power converters using a mixed-mode unterminated behavioral model

Abstract

With the high electromagnetic interference (EMI) noise generated by fast-switching-speed devices, it is crucial to learn about EMI noise generation and propagation in the systems and design effective EMI filters. EMI behavioral models have been verified as an effective tool to predict common-mode (CM) and differential-mode (DM) EMI noise and aid in EMI filter design. However, these models cannot predict the effect of the cross-coupled DM and CM noise, which is more likely to be present when operating at a high switching frequency. Accordingly, this paper explains the cross-coupled effect that noise generation and propagation have in an inverter system. A mix-mode unterminated behavioral model is proposed to capture the DM noise at the input DC terminals considering the mixed CM effect. The model accuracy is verified to 30 MHz in experiments carried out on a three-phase SiC MOSFET inverter.