Capacitive Couple-Based Transient Current Commutation in Solid-State Circuit Breakers

This letter presents a new auxiliary circuit to achieve transient current commutation (TCC) in dc solid-state circuit breakers (SSCBs). The auxiliary circuit consists of two parts: active injection circuits (AIC) and capacitive couplers. There are two contributions. First, coupling capacitors between AIC and the main branch are introduced to prevent short circuit failures in the auxiliary branch. Second, a boost converter-based resonant circuit is presented for AIC to achieve TCC in the main branch through couplers. The presented AIC tunes the duration time and amplitude of injected countercurrent pulses during dc current interruption. The working principle and design procedure of the auxiliary circuit are presented. The proposed topology is verified by experiments of a 2 kV/100 A dc SSCB prototype under load current interruption. The experimental results show that the injected pulse current through couplers reaches 110 A, and it decays to zero within 12.5 μs. The total reaction time interval including the communication delay and the AIC current rising delay is 108 μs. Meanwhile, the peak voltages across the main branch and the coupler reach 2099 V and 2193 V, respectively.