Influence of Gate Resistance on Short Circuit Dynamics in High Power SiC MOSFET Inverters

Abstract

With a trend for higher battery voltages, increasingly more stress is placed on power electronics in case of failure mode such as short circuit. Safety features like soft turn off are readily available in modern gate drivers, however, careful adjustment of the operation point is mandatory to achieve maximum robustness. In this study, we investigate the influence of external gate resistance on the dynamic short circuit behavior of power modules for e-mobility application utilizing silicon carbide metal-oxide semiconductor field-effect transistors. Large gate turn off resistance helps facilitate a pronounced decrease in overvoltage by reducing the current slope. Increased robustness is achieved by limiting acute stress acting on the semiconductor while switching curves reveal an increase in maximum feasible short circuit energy with slower turn off. Eventually, highest ruggedness is achieved when carefully balancing overall and peak power dissipation. Results presented here are meant to provide insights into the correlation between switching speed and safe operation of the device in order to take full advantage of the capabilities of the technology in terms of performance as well as reliability.