Research on Improving the Avalanche Current Limit of Parallel SiC MOSFETs

The transient overvoltage caused by coupling of loop inductance during rapid turn off of a silicon carbide metal-oxide-semiconductor field-effect transistor (SiC MOSFET) can easily induce avalanche breakdown. Meanwhile, the instantaneous high-density heat flux generated by energy dissipation can create significant electrothermal coupling stress, potentially leading to device failure under severe conditions. To address the issue that the multi-chip parallel structure of power modules cannot linearly enhance avalanche withstand capability, an innovative device screening method based on parameter matching is proposed in this paper. The effectiveness of the proposed solution is verified through experiments, with the total current limit of dual-tube parallel devices and three-tube parallel devices achieving 1.9 times and 2.4 times that of single-tube devices, respectively. This research is of great significance for improving safe and reliable operation of the system.