Solid-state circuit breakers (SSCBs) provide several advantages over conventional mechanical circuit breakers. These include precise DC grid integration, current control, remote operation, and customizable protection settings. Additionally, with silicon carbide (SiC) MOSFET power modules, faster response time and compact size are targeted. With compact size being a target, and quadratic power losses of SiC power modules, thermal management solutions must be considered. This paper describes a first approach to thermal simulation for predicting SiC module junction temperature in SSCBs. Additional simulations predict the temperature build-up inside of an enclosure. An iterative process is laid out for heat sink optimization to maintain a safe junction temperature under steady-state conditions.

Wide band-gap (e.g. silicon carbide) power semiconductor devices find a good fit for solid state circuit breaker (SSCB) applications due to the superior performances like low conduction resistance and high blocking voltages. Although the SiC power devices could help reduce the SSCB conduction losses, the thermal stress is still one of the major challenges, especially during overload conditions, where a great amount of heat is generated in a short period. This paper investigates the use of phase change material (PCM) embedded heat sink as the cooling solution for wide band-gap devices in SSCBs to address the transient overload thermal stresses. Laboratory experiments for PCM filled heatsinks have been conducted and compared with the non-PCM filled heatsinks in this paper to explore its potential advantages in managing overload thermal requirement for wide band-gap devices. The results revealed that after the PCM is activated, the temperature rise speed under transient overload is greatly reduced within a timeframe which means the PCM based heatsink is effective to address the overload thermal stress and can also be a thermal reservoir temporarily in case any fan cooling fails.

Power semiconductor devices play an important role in circuit breakers (CB) to provide fast, arc-less, fault current interruption in dc distribution systems. Series connection of power devices is often used to increase the breaker voltage rating for application in medium voltage dc systems. This paper presents a low-cost gate driver circuit based on passive components which can achieve gate control of the series power device stack using only a single isolated gate driver IC. The circuit provides reliable coupling of the CB logic control signal while achieving a balanced device voltage distribution during the fault turn-off event. Transient voltage suppression (TVS) diodes are utilized to limit the turn-off voltage of the power devices and provide the current return path for the gate capacitor discharge of the upper device(s). Simulation and experimental results are provided to verify circuit operation in a dc solid state circuit breaker system.