Improving Low-Voltage DC Circuit Breaker Performance Through an Alternate Commutating Circuit

Current interruption in dc circuits is more challenging than in their ac counterparts due to the absence of natural current zero-crossing and resistive nature of the dc grids. This article summarizes the current dc breaker technologies and proposes new alternate methods for low-voltage applications. The proposed mechanisms utilize two switches, of which one generates zero crossing with an alternate oscillatory circuit for the other one, which can be a conventional ac breaker and is used in the main circuit. This is different than the conventional single-switch commute-and-absorb method used in high-voltage dc systems. It is shown that the proposed oscillatory circuit improves the fault current extinction and significantly reduces the voltage slew rate of conventional mechanical and solid-state switches. Thus, the proposed mechanism is capable of interrupting high dc currents with a minimal arc through a less expensive ac circuit breaker. Simulation and hardware results are provided to show the efficiency of the proposed breakers.