Stability Analysis and Improvement for SSCB with Single-Gate Controlled Series-Connected SiC MOSFETs

Silicon carbide-based solid-state circuit breaker (SSCB) exhibits superior performance in dealing with the interruption of dc short-circuit current compared with the mechanical switch. The blocking voltage of commercially available SiC devices still cannot meet the voltage requirements. Series-connected SiC mosfets providing higher blocking voltage based SSCB with the single-gate driver has been proposed previously. However, the sustained oscillation phenomenon, unacceptable false gate-trigger, and severely unbalanced voltage distribution have been observed after the energy-absorbing stage in the circuit. These phenomena are mainly caused by the capacitor coupling mechanism among the two series-connected devices due to specific circuit configuration. This article elaborates on the mechanism of the oscillation by establishing the small-signal models. Based on the stability criterion analysis, an effective damping method is proposed to improve the stability of the SSCB. Simulation and experimental tests have been conducted to verify the effectiveness of the proposed damping method.