SiC Based Solid State Circuit Breaker: Thermal Design and Analysis

Compared to conventional mechanical breakers, solid state circuit breakers (SSCBs) are well-known for the ultra-fast fault clearing speed and the arc-free current interruptions, making them a promising protection apparatus for electric vehicle charging infrastructure (EVCI), electrified ship and aircraft, and railway system applications. With the superior material properties of silicon carbide (SiC), the SiC based SSCBs are expected to achieve a lower conduction loss and a faster fault breaking speed in a smaller form factor. One remaining design challenge of SiC based SSCBs is to maintain the safe device junction temperature under all operation conditions, especially the overload conditions which cause escalated thermal stresses for power semiconductor devices. In this paper, the thermal performance of a SiC metal oxide semiconductor field effect transistor (MOSFET) based SSCB is experimentally evaluated under both nominal and overload conditions. Finite element models and thermal network models are constructed to estimate the overload withstand time of the SSCB prototype under a wide range of ambient temperatures. Moreover, the established overload evaluation strategy is applicable to not only SSCBs, but also power converters with a high requirement on their overload withstand capabilities.