Improving Surge Voltage and Power Loss of the MOV-MOV-C Approach for Low-Scale DC Solid-State Circuit Breaker Applications

The dc solid-state circuit breaker (SSCB) is commonly used to protect sensitive equipment and enhance system stability by quickly interrupting fault currents, thereby increasing overall safety. The double metal oxide varistors (MOVs) and the single capacitors are the snubber circuit topologies represented by MOV-MOV-C that have been successfully demonstrated through design and experimentation, effectively suppressing high-frequency oscillations caused by the capacitance of the MOV and blocking low-frequency harmonics introduced by the RC snubber. However, previous research highlights critical areas for improvement, particularly in reducing surge voltage across the main breaker switch, minimizing power loss in on-state normal operation, and discussing the overall design cost in low-scale applications. This article analyzes and compares power loss between different types of semiconductor switches to optimize and minimize it. The surge voltage also improves from the traditional MOV-MOV-C into a proposed enhancement incorporating a new MOV featuring a lower dc-rated and maximum clamping voltage aimed at optimizing surge voltage protection, represented by a Triple-MOV-C snubber circuit. A cost model for critical components was also developed to discuss the total design based on a low-scale dc SSCB application of both snubber circuits and validated through the graph. Finally, the validation of power loss and surge voltage improvements was conducted through small-scale experiments.