A Novel Bidirectional T-source DC Circuit Breaker for DC Microgrids

A bidirectional DC breaker based on T-source series circuit is presented in this paper, which can work in the application where require bi-directional power flow between different nodes of microgrid and loads. When a short-circuit fault occurs, the proposed topology utilizes a T-source transformer to naturally commutate off the thyristor(SCR) by coupling and reducing the current to zero through the thyristor, thus avoiding circuit breaking under high current operating condition, furthermore, this topology allows a response to faults on either the source or load side only using a single controlled switch, no additional passive components are required compared with the unidirectional series T-source circuit breaker topology. The analysis is performed to find the fault conditions that cause the bi-directional circuit breaker to trip when operating in a single load power system, the transfer function of this breaker circuit is deduced and circuit parameters is designed. Finally, the operation principle of the bi-directional circuit breaker is evaluated for both source and load side faults by using a simulation platform PSIM.