A Thyristor-Based Solid-State DC Circuit Breaker With a Three-Winding Coupled Inductor

Thyristor-based solid-state circuit breakers (TCBs) have become a popular protection solution for dc microgrids, due to their low construction cost, high efficiency, and fast response time. Despite numerous TCBs being proposed, the majority of them still suffer from low controllability, low current interrupting reliability, slow fault isolation, poor reclosing protection, and high conduction loss. Inspired by these issues, a novel TCB with a three-winding coupled inductor is proposed in this article. First, it could interrupt both operating and fault currents actively and reliably with its bidirectional symmetric construction, ensuring high controllability and reliability. Second, during the current interrupting process, the arrester immediately works after the proposed TCB acts, which makes the fault currents at both source and load sides drop, thus effectively suppressing the fault currents. Third, the capacitor and thyristors in the triggering circuits can automatically restore to their initial states after interrupting the current, thus ensuring a reclosing protection function with no extra operation sequences. Fourth, since the conducting branch only contains one set of parallel thyristors and an inductor coil, the conduction loss of the proposed TCB is low, thus ensuring effectiveness. The working principles, design guidelines, and experimental results are presented. The advantages of the proposed TCB are further demonstrated through comparison with some existing schemes.