Research Of Hybrid High-speed DC Circuit Breaker In Metro Vehicles

The DC circuit breaker of metro vehicle is responsible for the dual task of protecting the metro traction power supply system and vehicles.However,the electric arc is produced between the internal mechanical contacts during the process of closing and opening,which causes the equipment damage directly affect to the system's power supply and the subway vehicles operation safety.This paper takes the DC circuit breaker as the research object,and the hybrid switch arc extinguishing method is used to optimize the original topology in order to realize the high-speed non-arc breaking fault current of metro vehicle DC circuit breaker.Firstly,the working principle,structure,classification,advantages and disadvantages and application status of DC circuit breakers used in various fields at home and abroad are summarized,and the operating environment and operation characteristics of metro vehicles,the structure of the DC circuit breaker,working principle,electrical control logic and the disadvantages of the existence of the metro vehicle are understood.The reasons for the damage of the equipment and the two available non-arc measures are simulated and analyzed,which provides the foundation the theoretical and comparative analysis of the new idea of topology design for high-speed DC circuit breaker of metro vehicle.Secondly,the hybrid switch non-arc method is used to improve the topology of the vehicle DC circuit breaker.The overall structure of the hybrid metro vehicle high-speed DC circuit breaker includes mechanical switch,power electronic switch,buffer and energy absorption circuit,fault detection and control unit.The mechanical switch uses a high-speed electromagnetic repulsion switch,and power electronic devices select IGBT fully controlled devices.The influence of bus voltage,off current,buffer capacitance and stray inductance on power electronic switching elements is analyzed,and the buffer and energy absorbing branch is designed.The topology of hybrid metro vehicle high-speed DC circuit breaker,theoretical working principle and fault removal current transfer characteristics are determined.The parameters and equivalent circuit of short circuit fault of metro traction power supply system are analyzed.Finally,the simulation model of the hybrid metro vehicle high-speed DC circuit breaker is built in MATLAB/simulink to simulate the running environment of the remote fault,Compared with the theoretical current transfer characteristics,the results of this comparison shows that the expected goal has achieved,which strongly confirms that the hybrid metro vehicle high-speed DC circuit breaker can quickly remove the fault and improve the integrated automation level of Metro traction power supply system equipment.