A New Bidirectional DC Circuit Breaker with Fault Decision-Making Capability for DC Microgrid

DC circuit breaker (DCCB) plays an important role in DC system protection as an execution unit for disconnecting fault lines. However, due to the nature of DC current, it is a challenge for DCCB to quickly turn off and isolate fault current. Therefore, a new bidirectional DC circuit breaker with decision-making capability based on Z-source topology is proposed in this paper, which is able to respond to a fault in a few microseconds. The proposed topology uses only one coupled inductor with a central tap structure in the core part, which improves the utilization ratio of the coupled inductor and reduces the volume and cost of the DCCB. Compared with previous DCCBs, the proposed topology has a simpler structure, fewer windings and components, and smaller volume. In this paper, the turn off process of the proposed topology under the line fault condition is analyzed in detail, and the hardware circuit design process is given. The performance of the proposed topology was verified by MATLAB simulation and hardware experiments.