A Volume-Optimized Hybrid EMI Filter for Automotive Traction Inverters

Electromagnetic interference (EMI) filters play a cru- cial role in automotive inverters but can occupy a significant por- tion of the overall system volume, particularly in wide-bandgap (WBG) semiconductor-based designs, due to their higher power density compared to Silicon-based ones. To address this issue, this article proposes the use of active capacitors as a replacement for passive ones, effectively reducing the required common-mode (CM) inductance. A detailed analysis of the active capacitor operation is presented, along with design equations to aid implementation. Based on this approach, a hybrid EMI filter (HEF) is proposed. Experimental prototypes have been developed and tested to vali- date the concept. The results demonstrate that the HEF achieves comparable filtering performance to conventional passive designs while reducing the volume of magnetic components by 50%.