A Cost-Effective Design of Soft Turn-off Diode-Bridge Power Electronic Switch for High-Performance Hybrid DC Circuit Breakers

Generally, the diode-bridge power electronic switch (DB-PES) serves as a crucial component for interrupting fault currents in hybrid dc circuit breakers (HCBs). However, the cost-effectiveness of existing DB-PES solutions is not ideal enough, as it is challenging to achieve soft turn-off stress for IGBTs and low recovery stress for bridge-arm diodes simultaneously. This article provides an initial analysis of the transient recovery processes for the soft turn-off DB-PES in various topology configurations. The actual recovery effect is verified through experimental results based on the single DB-PES module constructed by low-cost standard recovery diodes. While ensuring recovery reliability, to reduce the component cost for both the IGBTs and bridge-arm diodes, a cost-effective DB-PES solution is designed by placing the MOV outside and adding an R-C damping circuit. Based on a 30 kV HCB prototype, the comprehensive experiments validate the feasibility of the proposed optimized solution. Compared to the existing solution, in the proposed solution, the transient power and turn-off energy loss of the IGBT decrease from 23 MW and 33 J to 5 MW and 14 J, respectively, and the recovery frequency of the bridge-arm diodes decreases from over ten times to only a single time. Thus, with the same interruption capacity, the total cost can be reduced by over 20%.