A Family of Bidirectional Solid-State Circuit Breakers With Increased Safety in DC Microgrids

Increasingly, dc microgrids are attracting attention because of their universality, high efficiency, and potential application market. To enhance the fault protection of dc systems, solid-state circuit breakers (SSCBs) have been developed to perform fast protection. However, there are still challenges including decoupling of the source and load during operation, using the switches of the main path, MOV's reliability, and charged capacitors before reclosing. In this article, three bidirectional dc SSCBs are proposed that address the aforementioned issues using a third switch to bypass the fault current, eliminating the snubber from the power line, not using the main path switches, and placing a snubber that provides a discharged capacitor before reclosing. These also provide the structure extra reliability and increased voltage utilization rate of the switches. These features increase both device and human safety. The working principle and operating modes of these SSCBs along with the equations for calculation of crucial time intervals, voltages, and currents and the design procedure are provided, and the experimental results demonstrate the proper performance of the topology and validate the findings.