Temperature-Dependent Mechanism of Short-Circuit Voltage Imbalance in Series-Connected SiC MOSFETs

The series connection of SiC MOSFETs is a cost-effective solution to enable higher voltage applications. Nevertheless, proper voltage sharing remains challenging for reliable operation. This paper investigates the voltage imbalance issues during short-circuit stress. Experimental results show the unbalanced voltage of two devices even with similar characteristics. Since the imbalance issue is affected by swapping only the two gate drivers upside down, the intrinsic delay between gate drivers is regarded as an initial cause. The results from mixed-mode electro-thermal TCAD simulations indicate that the temperature-dependent mechanism plays a large role in the voltage imbalance.