Evaluation and Experimental Comparison of Overvoltage Suppression Methods for DC Circuit Breakers

Among the semiconductor-based dc circuit breaker (DCCB) topologies (e.g., solid-state circuit breakers, hybrid circuit breakers), a common element is the paralleled branches of power semiconductor switches and energy absorption components. To interrupt dc-side faults, the power switches turn off to redirect the fault current to the energy absorption elements, which absorb the fault energy. Metal-oxide varistors (MOVs) are currently the most widely used candidate for energy absorption. However, transient voltage overshoots can occur during the commutation of the fault current from the semiconductor switches to the MOVs. This is problematic as they can damage the paralleled semiconductors and potentially the mechanical switch in the case of hybrid circuit breakers. A number of DCCB overvoltage suppression methods have been proposed in the technical literature. However, there is a lack of systematic evaluation and comparison of these methodologies in terms of their suppression performance, design procedures, etc. Therefore, to inform designers of the advantages and drawbacks of each method and to guide the design procedures, the state-of-the-art DCCB overvoltage suppression techniques are surveyed and new analytical results are presented. Their performance is experimentally compared on a 1.2 kV DCCB hardware platform under two different DCCB tripping strategies.