An Improved Topology of Direct-Current Circuit Breaker With Superconducting Fault Current Limiter and Self-Charging Capacitor

DC circuit breakers based on artificial current zero can interrupt a fault current with a low cost and a fast operation. However, its working reliability is reduced by the charging device of the commutation capacitor which generates the artificial current zero. The objective of this paper is to propose a new topology to avoid the pre-charging process. A resistive type SFCL is used to limit the short circuit current. Meanwhile, the voltage on the quenched SFCL charges the commutation capacitor. The operation sequences are given, and a simulation proved the feasibility. The simulation result shows that the voltage on the SFCL is able to charge the commutation capacitor within a few milliseconds, which is enough to generate an artificial current zero, and then the DC circuit breaker interrupts the fault current successfully.