A Series-Type Hybrid Circuit Breaker Based on Flying Capacitor Multilevel Injector With Balanced Switching Operation and Current Limiting Capability

In this article, a series hybrid circuit breaker based on a flying capacitor multilevel injector (FCM-SHCB) is proposed for MVDC and LVDC, which utilizes the multilevel characteristic of FCM to realize the fault-current-limitation modulation and extend operation windows for mechanical switch (MS). Meanwhile, by fully exploring the redundant states of the FCM structure, the proposed FCM-SHCB can avoid the high-frequency operation of one single device in conventional S-HCBs, realizing balanced switching operation of the power semiconductor devices and reducing switching frequency without sacrificing the injection performance. The operation principle and parameters design consideration are detailed. A proof-of-concept FCM-SHCB prototype experimentally demonstrates the proposed solution can maintain the high-speed fault-current breaking ability (150 V/15 A/
$6~\mu $
s) while obtaining balanced switching operation (half-reduced switching frequency) and current limiting capability.