基于MOSFET的直流电子辅助断路器设计及开断性能优化方法研究

Design of MOSFET-based DC Electronic Auxiliary Circuit Breaker and Its Optimization Method of Breaking Performance

为提高传统机械式塑壳断路器(mechanical molded case circuit breaker,MCCB)的开断容量和开断速度,提出了使用金属—氧化物半导体场效应晶体管(metal oxide semiconductor field effect transistor,MOSFET)改进传统MCCB拓扑的方法,设计了一款新型混合式直流断路器,通过电力电子换流电路辅助MCCB切断直流短路故障电流。该拓扑能够将电力电子换流电路的故障电流承受时间限制到100~200μs,利用功率等级较低的开关元件即可实现与混合式直流断路器相近的开断性能,因而能够大幅降低断路器研制成本。其次,设计了一种改进的RC缓冲回路,可将关断电压尖峰由30 kV抑制到600 V,由此通过保护拓扑中的MOSFET来提升断路器的稳定性、延长其电寿命。最后对所设计的新型混合式直流断路器拓扑建立仿真模型,功能验证结果证实了该方案的可行性和有效性。

In order to improve the breaking capacity and breaking speed of the traditional Mechanical Molded Case Circuit Breaker(MCCB),this paper improves the topology of traditional MCCB based on Metal Oxide Semiconductor Field Effect Transistor(MOSFET)by assisting the MCCB to cut off DC short-circuit fault current using the power electronic commutation circuit.This topology limits the fault current withstand time of the power electronic commutation circuit to 100~200μs,and uses switching elements with lower power levels to achieve a breaking performance similar to that of a hybrid DC circuit breaker at a lower cost.An improved RC snubber circuit is designed,which can suppress the turn-off voltage spike from 30 kV to 600 V.The stability of the circuit breaker is increased and its electrical life is prolonged through protecting the MOSFET in the topology.Finally,a simulation model is established to verify the function of the designed new hybrid DC circuit breaker topology,which supports the feasibility of the method.