A Single-Coupling-Injection Series-Type Hybrid Circuit Breaker Using Diode Clamping Switching

The series-type hybrid circuit breaker (S-HCB) is an attractive solution for fault protection in medium and low-voltage dc distribution networks, effectively suppressing fault current rise during breaking while maintaining low conduction losses. However, their multilevel injector used for active current modulation suffers from complex topology and control, while the mechanical switch's (MS) current zeroing time is significantly affected by line inductance, leading to unreliable breaking. In this article, a single-coupling-injection S-HCB is proposed. By using diode clamping switching, it provides an approximately zero-voltage environment throughout the entire MS opening process with a single coupling injection. This significantly simplifies the topology and control of the VI unit, enhancing the practicality of S-HCB. In addition, it features a self-contained breaking loop, decoupling the MS's current zeroing time from line inductance. This ensures a more stable operating window for the MS, improving the reliability of S-HCB. To validate the proposed S-HCB, simulations and experiments of a 200 V/20 A scale-down prototype are conducted. Results show that the proposed S-HCB can reliably break the operating/fault current with simplified topology and control in the VI unit.