A Diode-Free MOV2-RC Snubber for Solid-State Circuit Breaker

ABSTRACT

This paper presents a diode-free double metal oxide varistor-resistor-capacitor (MOV2-RC) snubber to provide overvoltage protection in dc solid-state circuit breakers (dc SSCBs). MOV2-RC snubber is introduced and investigated for SSCBs application. The proposed MOV2-RC snubber prevents voltage overshoot and ensures smooth turn-off voltage slew rate of SSCBs. Meanwhile, compared with conventional MOV-resistor-capacitor-diode (MOV-RCD) snubber, utilization of a low-voltage MOV (LMOV) to replace the diode avoids the influence of availability issue of state-of-the-art SiC Schottky diode raised by global power semiconductor shortage due to coronavirus disease 2019 (COVID-19). It also reduces the cost of snubber circuit for SSCBs. Working principles and design procedures of the MOV2-RC snubber are presented. The effectiveness of the proposed snubber circuit is verified by experiments with a 400V/140A dc SSCB prototype. The experimental results show the clamping voltage of 1.1 kV and turn-off dv/dt of 7.9 V/ns. The key component of MOV2-RC snubber (LMOV) has 30 times lower cost and 3 times better availability compared to MOV-RCD-based counterpart. © 2022 IEEE.