Research on the Common Mode EMI Suppression Method for SiC Traction Converters

The SiC traction converter possesses the advantages of low power loss and high operating frequency. However, the faster switching speed and higher switching frequency of SiC devices also lead to more severe electromagnetic interference (EMI) issues in traction drive systems. This paper proposes a common-mode (CM) EMI suppression method specifically for SiC traction converters. Firstly, the CM conducted interference paths in the traction drive system are studied, and an equivalent circuit modeling method for CM EMI applicable to SiC traction converters is presented. The influence of applying SiC devices on the magnitude of CM EMI in the traction drive system is analyzed. Furthermore, a CM EMI suppression measure is proposed by introducing nanocrystalline chokes at the input and output ports of the SiC traction converter, along with a design method for the parameters of the nanocrystalline choke. Finally, a low-power experimental platform for the SiC traction converter is established, and experimental verification is conducted. The results demonstrate that the proposed suppression method effectively suppresses CM currents in the system.