Low-Loss Bidirectional Solid-State Circuit Breakers With Reliable Breaking Capability for Protecting DC Microgrids

Silicon-controlled rectifier-based dc solid-state circuit breakers (SCR-SSCBs) have received an increased attention for their ease of control and high efficiency, but their considerable conduction losses remain a major disadvantage. This article presents a new bidirectional SCR-SSCB topology, which reduces the conduction losses by ∼50%, with the loss reduction attributed to an inductor being eliminated from the main circuit during normal operation. This is achieved by conducting current through one semiconductor switch instead of two as in the conventional devices. In addition, the presented topology enhances the reliability of protection by enabling a controlled interruption of short-circuit faults in which fault interruption is not affected by the parameters of external systems to which the circuit breaker is connected to. A second topology that reduces the size of the capacitors in the commutating circuit is also introduced. A detailed analysis of the operating principle of the two novel topologies is presented. Recommendations supported by mathematical modeling are provided for selecting the relevant components of the devices. The performance of the two topologies was verified through simulation and experimental tests.