Bidirectional Coupled Inductor Based Hybrid Circuit Breaker Topologies for DC System Protection

This paper introduces a hybrid DC circuit breaker (DCCB) topology suitable for protection of bidirectional DC systems such as DC micro-grids with energy storage. The proposed DCCB utilizes series resonance of a 3-winding coupled inductor and a charged commutation capacitor to inject reverse current to the fault, thereby forcing a zero crossing in fault current to commutate the series path switch and interrupt fault. The commutation capacitor is actively charged from the DC source through circuit elements. Also, as the series path mechanical switch is turned off at zero current, no arc is formed between separating contacts of the switch. Fault interruption time is programmable based on the choice of passive elements. A modification of the proposed topology using two 2-winding coupled inductors is also explored. Analysis and operation of the proposed circuit breaker topology is illustrated with design equations and its functionality is evaluated through relevant simulation and experimental results.