A Low-Parasitic Integrated CM EMI Filter Structure With Additional Terminals for SiC Power Modules: Analysis, Design, and Experimental Validation

Abstract

Silicon carbide (SiC) devices operate at higher switching speeds and frequencies than traditional silicon (Si) devices, and also generate more significant common-mode (CM) electromagnetic interference (EMI). Integrated EMI filters within the power module offer better performance than external filters above 10 MHz. But the existing integrated design still suffers from insufficient filtering performance below 10 MHz and high core losses in the CM inductors due to the parasitic inductances and terminal placement. To address these problems, this article presents a novel integrated EMI filter structure within the SiC power module. Featuring a low-leakage stripline inductor and additional terminals, it enhances EMI suppression over a wider frequency range and effectively reduces the core losses. A frequency-domain analysis model is developed to analyze the impact of key parasitic parameters from 150 kHz to 30 MHz, addressing gaps in current theoretical analysis. Based on this, the proposed EMI filter structure is introduced. A power module prototype employing this structure is fabricated, and an EMI test bench is constructed. Experimental results from 150 kHz to 30 MHz demonstrate that the proposed structure achieves superior filtering performance to the existing structure, and also achieves a 10 dB improvement compared to the external filters.