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DC microgrids have attracted increasing attention due to their high efficiency, simple control, and high power quality; however, circuit fault protection remains a technical challenge. Z-source circuit breakers (ZSCBs) have provided a promising solution with fast, autonomous, and arcless fault clearances. To further provide bidirectional operation capability and enhanced performance, a bidirectional ZSCB based on coupled inductors is proposed and well designed in this article. It can offer bidirectional power flow and fault disconnections in a compact size. The working principle and circuit analysis are elaborated with mathematical models, which cover the entire fault-clearing transient and can provide insightful guidelines for breaker design and component sizing. Moreover, a crowbar-type switch enabling manual tripping operation of the proposed ZSCB is integrated. Finally, Saber-based simulations verify the effectiveness of the models and the design, which are further validated by a 48 V/230 W laboratory prototype.