Comparison of Surge Voltage Reduction and Economic Efficiency of DC SSCBs According to MOV and RCD Snubber Combination

Metal oxide varistor (MOV) is a nonlinear resistive element whose resistance decreases rapidly when the applied voltage exceeds a threshold value. A dc solid-state circuit breaker (SSCB) uses MOVs or MOV with resistor-capacitor-diode (RCD) snubber circuit combinations to reduce the surge voltage that occurs when breaking a fault current. The more MOV and RCD circuit components are added, the greater the surge voltage reduction effect. However, an increase in several parts leads to a rise in the cost of the snubber circuit. This article aims to find an economical circuit structure that improves the surge voltage reduction rate and does not increase the cost significantly by adding MOV and RCD snubber combinations to the conventional MOV-based surge voltage reduction circuits. First, three circuit combinations employing MOV, R, C, and diodes are presented. We confirm the proposed snubber circuit structures effectively reduce surge voltage by comparing surge voltage reduction rates through theoretical analysis, simulation, and experiment. Second, cost model analysis for the proposed circuits is used to calculate the total price of components. Finally, the economic feasibility of the proposed snubber circuits is evaluated by the cost required to achieve a 1% surge voltage reduction rate. The results of this article facilitate the selection of an economical circuit structure that combines additional MOV or RCD snubbers in the conventional MOV-based snubber circuits to reduce the surge voltage of SSCBs while minimizing cost increase.