A 900V/4mΩ/80A Bidirectional SiC DC Solid State Contactor (SSC)

Compared with the Electromechanical Contactor (EMC), Solid-State Contactor (SSC) is attractive due to the absence of moving parts and arcing. An SSC is also much superior in high current switching capability to an EMC; hence can provide precise and faster protection to sensitive equipment. The lifetime is also substantially improved since its mechanical counterparts can only switch several hundred cycles at the rated current. Traditionally the main issue of the SSC has been the higher power loss and cost. This situation is dramatically improving with the commercialization of low conduction loss wide bandgap (WBG) power devices. This paper introduces the design and implementation of a 900V/80A SiC Solid-State Contactor (SSC) for an 800V DC or single-phase AC system. Advanced natural convection thermal design with various thermal interface materials is compared, and the tested thermal resistance is only 1.9°C/W with an integrated heatsink. The overcurrent turn-off is verified at 920V/140A test condition, and the soft turn-off is completed within 8.2µs.