中文摘要：

混合型直流断路器由高速斥力开关和固态开关并联组成。本文对一种混合型直流断路器中晶闸管关断时过电压抑制问题开展了研究，对影响晶闸管关断过电压的因素进行了分析，提出了在电感两端并联续流二极管和在晶闸管两端并联缓冲电路的解决方案。开展了有无缓冲电路和续流二极管、不同缓冲电路方案的对比试验，从而确定了缓冲电路的结构和参数，并进行了优化设计后的直流断路器样机短路分断试验，验证了所提过电压抑制方案的有效性。

英文摘要：

Hybrid DC circuit breaker consists of high speed electro-magnetic repulsion switch and solid-state switch in parallel.In this paper,the suppression method of thyristor’s turn-off over-voltage for a hybrid DC circuit breaker is researched.The effect factors of thyristor’s turn-off over-voltage are analyzed.The solution by connecting the freewheel diode to the inductance in parallel and connecting snubber circuit to thyristor is proposed.The contrast tests of different snubber circuits and with the freewheel diode or not are carried out.The short-circuit test of optimized prototype is finished and the effectiveness of suppression method is demonstrated.