A Bidirectional MVDC Solid-State Circuit Breaker Based on Mixture Device

The mixture unidirectional solid-state circuit breaker (SSCB) based on transistor-based devices [i.e., IGBT-based line commutation switch (LCS)] and the thyristor-based devices can combine their respective advantages, however, the conduction loss and cost may increase significantly when expanding to a bidirectional topology because the number of IGBTs had to be doubled with the expansion of unidirectional LCS structure to bidirectional LCS structure composed of two groups of IGBTs in reverse series. In this letter, a full-bridge mixture bidirectional SSCB (FB-MSSCB) requiring only one unidirectional LCS is proposed, the required number of IGBTs can be reduced by at least half compared with other mixture bidirectional SSCB topologies in the same voltage and current level applications. As a result, the FB-MSSCB has advantages of more economic design and higher efficiency, the conduction loss can be reduced by at least 23.3% in 10 kV MVdc system, while retaining other advantages of mixture bidirectional SSCB, such as the ability to actively interrupt bidirectional fault currents, without introducing additional thyristors, charging power supply, and charging strategy. The working principles and designing guidelines is presented in detail. The feasibility and effectiveness are verified by experiment results and comparative analysis.