Temperature-Dependent Short-Circuit Capability of Silicon Carbide Power MOSFETs

TLDR

The study evaluates the short‑circuit ruggedness of modern commercial silicon carbide MOSFETs. The authors test three 1200‑V SiC MOSFETs across case temperatures 25–200 °C and bus voltages 400–750 V, and model their short‑circuit behavior with an electrothermal simulation that estimates internal temperature and leakage currents. Short‑circuit failure in SiC MOSFETs arises from thermal‑generation‑current‑induced runaway or high‑temperature gate‑oxide damage.

Abstract

This paper presents a comprehensive short-circuit ruggedness evaluation and numerical investigation of up-to-date commercial silicon carbide (SiC) MOSFETs. The short-circuit capability of three types of commercial 1200-V SiC MOSFETs is tested under various conditions, with case temperatures from 25 to 200 °C and dc bus voltages from 400 to 750 V. It is found that the commercial SiC MOSFETs can withstand short-circuit current for only several microseconds with a dc bus voltage of 750 V and case temperature of 200 °C. The experimental short-circuit behaviors are compared, and analyzed through numerical thermal dynamic simulation. Specifically, an electrothermal model is built to estimate the device internal temperature distribution, considering the temperature-dependent thermal properties of SiC material. Based on the temperature information, a leakage current model is derived to calculate the main leakage current components (i.e., thermal, diffusion, and avalanche generation currents). Numerical results show that the short-circuit failure mechanisms of SiC MOSFETs can be thermal generation current induced thermal runaway or high-temperature-related gate oxide damage.