Simulation and analysis of body overvoltage based on three-dimensional car body model and actual grounding system

During the driving process of high-speed Electric Multiple Unit (EMU), the main circuit breaker will be operated frequently, resulting in transient over-voltage, which seriously endangers the operation of on-board electrical equipment. Based on a certain EMU, this paper constructs a three-dimensional vehicle body and high-voltage cable model. On this basis, considering the EMU grounding system comprehensively, an equivalent model of vehicle body over-voltage caused by the operation of the main circuit breaker is constructed, and the distribution of vehicle body over-voltage caused by this is analyzed. The actual three-dimensional model of vehicle body and highvoltage cable is established and embedded in the circuit module, so that the over-voltage characteristics of vehicle body at a specific position can be obtained. The simulation results show that the over-voltage is about 3.81kV, the oscillation time is about 28us, and the frequency spectrum is mainly 1.5684mHz, which conforms to the basic characteristics of over-voltage. After obtaining the amplitude and frequency spectrum of vehicle body over-voltage caused by VCB (Vacuum Circuit Breaker) operation, the influence of grounding system on vehicle body over-voltage is studied. The results show that the grounding resistance and inductance have certain influence on vehicle body surge over-voltage amplitude.