Low-loss Bidirectional DC Circuit Breaker with Capacitance Self-charging Ability

Failure to interrupt such fault currents promptly can lead to severe damage to system equipment. As a critical fault isolation device, the development of high-performance DC circuit breakers is essential for ensuring the safe and stable operation of DC power supply systems.

Solid-state circuit breaker has high on-state loss, low energy transmission efficiency and complex heat dissipation design. The capacitance in the artificial current zero-crossing circuit of the mechanical circuit breaker needs to be pre-charged and an additional charger is required, increasing the cost of the circuit breaker. Hybrid circuit breaker combines the advantages of mechanical DCCB and solid-state DCCB, but there are still problems such as slow commutation speed and high cost. In addition, DC systems often need bidirectional energy flow, but at present, the research of bidirectional DC circuit breakers mostly focuses on the structure of solid-state DCCB, and there are few related researches on mechanical

DCCB and hybrid DCCB, which limits its application scope.

To address the existing issues of high power losses and the need for external capacitor pre- charging in current circuit breakers, this paper proposes a low-loss bidirectional DC circuit breaker with capacitance self-charging ability. The breaker adopts a vacuum switch as the main branch conducting switch, reducing switching devices losses by approximately 90% compared to solid state circuit breakers and significantly improving energy transmission efficiency. Furthermore, the capacitance charging scheme is optimized, adopting a capacitance charging scheme powered by the system voltage, eliminating the need for an external charger required by traditional mechanical DCCBs. Additionally, simulations confirm that the proposed breaker can effectively interrupt both forward and reverse fault currents, making it suitable for systems with bidirectional power flow.