Topology design of current injection DC circuit breaker based on coupling reactor

DC circuit breakers are one of the key equipment of photovoltaic(PV) DC systems. Aiming at the problems of insufficient fault current limiting ability, severe breaking arc, and serious contact ablation of traditional circuit breakers in the junction box of PV system, a current injection DC circuit breaker topology based on coupling reactor is proposed in this paper. The thyristor device is used to transfer the fault current of the mechanical switch branch in this topology to suppress the breaking arc from the perspective of energy transfer. At the same time, a coupling reactor is added between the main branch and the mechanical switch branch, and a resistance-capacitance hybrid current limiting branch is added to the main branch. The rising speed of the fault current is suppressed effectively, the transfer speed of the fault current is accelerated, and the breaking arc time is shortened. The principle analysis and parameter design of the proposed circuit breaker topology are completed in this paper, the influence of the parameters of the coupling reactor and the resistance-capacitance hybrid current limiting branch on the fault current transfer time is analyzed and verified by the MATLAB/Simulink platform. The results show that the topology can suppress the arcing and accelerate the arc extinguishing speed significantly, which can reduce the fire hazard of the junction box and improve the operation reliability of the PV system effectively.