面向碳化硅电流源逆变器的过电压保护方案

Current source inverters (CSI) are typically used for high-power medium voltage (MV) applications due to their inherent advantages of four-quadrant operation, short-circuit protection, and the absence of electrolytic capacitors at the DC-link. Wide bandgap (WBG) technology has led to the re-emergence of CSIs for MV solid-state transformers (SST), electric vehicles, traction applications, and renewable energy systems. The reliability of converter systems is critical for their widespread adoption. The over-voltage caused by interrupting the DC-link inductor current is a major concern for CSIs. With faster-switching devices, the device should be protected within a few microseconds. This paper compares and discusses the limitations of the existing over-voltage protection (OVP) schemes and proposes two over-voltage schemes that enable lower clamping voltage across all three phases. The OVP boards also help limit the system to its rated voltage. A 3.3 kV CSI hardware prototype was built using SiC MOSFETs and diodes. Experimental results are presented to validate the effectiveness of the proposed OVP board.