Gate Voltage Oscillation Mitigation in Solid-State Circuit Breakers with Single-Gate Driven Series-Connected Power Devices

Solid-State circuit breakers (SSCBs) using series-connected power devices (SCPDs) have broad prospects in dealing with the increasing blocking voltage applications. Compared with traditional gate drive schemes, single gate drivers (SGDs) based on passive devices exhibit the advantages of simple structure, low cost, compact design, and high reliability. However, due to the capacitor coupling mechanism among SCPDs, sustained gate voltage oscillations (GVOs) during the voltage recovery process were observed, leading to serious instability problems, such as SSCB operation faults and failure to clear the short-circuit current in time. After reviewing existing SGDs for SCPDs in SSCBs, including circuit structure, working principles, and design consideration, a novel SGD scheme by adding an extra gate diode is proposed in this paper to effectively mitigate unwanted GVOs. Specifically, the small-signal model of the proposed SGD is established and the stability analysis is presented to reveal the inherent mechanism of GVOs. Then, the impact of snubber circuits on the stability region and time delay during the turn-off procedure is studied. Based on the pole-zero map and root locus analysis, appropriate snubber circuit parameters are determined. Main simulation and experimental tests under various scenarios have been conducted to verify the effectiveness of the proposed design.