Efficiency and EMI Analysis of WBG-based Multilevel Inverters for 800 V Electric Vehicle Traction Systems

This paper presents a comprehensive investigation into the efficiency and common-mode electromagnetic interference (CM EMI) characteristics of an electric vehicle (EV) traction drive using wide bandgap (WBG)-based multilevel inverter (MLI) topologies, three-level T-type (3L-T) inverter and three-level neutral point clamped (3L-NPC) inverter in comparison with the conventional two-level (2L) inverter. The device analysis reveals that the SiC-based 2L inverter exhibits 30% higher efficiency than the Si-IGBT-based inverter during low torque and speed operations. Additionally, an efficiency comparison demonstrates that the 3L-T inverter achieves a notable overall drive efficiency improvement of up to 2.62% compared to the 2L inverter, particularly in the low-speed torque range. Furthermore, the CM EMI of the SiC-based 3L-T inverter with 50 kHz of switching frequency is estimated to be 15-50 dBμV lower than that of the 2L SiC-based inverter with 20 kHz of switching frequency. These findings validate the viability of WBG-based MLIs as a promising solution for EV traction systems.