A Novel Hybrid DC Circuit Breaker with Reverse-Biased Voltage Source for MVDC

DC circuit breakers are essential building blocks for the protections in the DC network systems. The hybrid circuit breaker combines the merits of the solid-state circuit breakers and mechanical switches, featuring higher efficiency and fast speed. However, even state-of-the-art hybrid circuit breakers require low-rating solid-state switches in the main current path, and these switches lead to significant losses as power ratings scale up to Medium Voltage DC (MVDC), posing significant thermal management challenges. To address this issue, this paper proposes a novel hybrid DC circuit breaker that removes solid-state switches in the main current path by adding a reverse-biased voltage in the commutation path. The added reverse-biased voltage consists only of a half-bridge with a capacitor rated within several hundred volts for a 12 kV medium voltage system. This configuration not only eliminates the need for solid-state switches in the main current path but also facilitates the commutation process, enabling fast current commutation. A detailed operation principle and design consideration are presented in this paper. Simulation and experimental results are presented to valiadate the proposed topology.