Novel Hybrid DC Circuit Breaker Based on Series Connection of Thyristors and IGBT Half-Bridge Submodules

Hybrid dc circuit breakers (HCBs) are vital equipment in dc grid systems. However, HCBs are usually costly since massive full-controlled power semiconductors are required to withstand high surge voltage and current stresses during current interrupting. Thyristors are good alternatives in realizing HCBs in view of their low cost and high current carrying capability; however, turning off the thyristor fast and reliably is a challenging task. In this article, a novel HCB topology is proposed, of which the solid-state part is realized by hybrid connection of thyristors and insulated gate bipolar transistor (IGBT) half-bridge submodules. The use of IGBT half-bridges provides a negative voltage across the thyristors to turn them off; accordingly, thyristors withstand a major of turn-off surge voltage instead of IGBTs. By this means, a low-cost HCB can be established while maintaining a high breaking speed. Besides, fast reclose and rebreak function is provided by the proposed topology. Operation principle and design consideration of the novel HCB topology are analyzed in detail, and the effectiveness of the proposed HCB is verified by both software simulation and downscaled experimental results.