基于移相全桥DC-DC变换器的城市轨道交通车辆高频充电机软开关实现方法

Realization Method for Urban Rail Transit Vehicle High-frequency Charger Soft-Switching Based on PS-FBC

目的:为了提高城市轨道交通车辆充电机的供电效率和功率密度,基于软开关技术,对PS-FBC(移相全桥DC-DC变换器)在轨道交通车辆高频充电机中的应用进行了研究。方法:分析了PS-FBC电路在3种工作模态下的运行特点,建立了过谐振模态中高频电流与电容电压的时域解析数学模型。基于该模型深入分析了电压极性翻转特性,探究了死区效应下电压极性翻转的触发条件,提出一种死区时间优化设计方法。通过PSIM软件对PS-FBC时域解析数学模型进行了仿真验证。结果及结论:PS-FBC工作在重载且过谐振条件时,将开关频率设置在靠近谐振频率附近,可以避免电压极性翻转现象的发生。通过合理设计开关死区时间,可以改善软开关的工作特性,降低PS-FBC的系统损耗,提高城市轨道交通车辆充电机的供电效率。通过多种工况下的仿真结果,验证了死区时间优化设计方法的有效性。

Objective:In order to enhance the power supply efficiency and power density of chargers for urban rail transit vehicles,the application of PS-FBC(phase-shifted full-bridge DC-DC converter)based on soft-switching technology is investigated.Method:The operational characteristics of the PS-FBC circuit in three working modes are analyzed,and a time-domain analytical mathematical model is established for high-frequency current and capacitor voltage in the over-resonance mode.The voltage polarity reversal characteristics are thoroughly examined based on this model.Additionally,the triggering conditions for voltage polarity reversal under dead-zone effects are explored,and an optimization method for dead-zone time design is proposed.The PS-FBC time-domain analytical mathematical model is simulated and verified using PSIM(physical security information management)software.Result&Conclusion:When the PS-FBC operates under heavy load and over-resonance conditions,setting the switching frequency close to the resonance frequency can prevent voltage polarity reversal.By designing the switch dead-zone time reasonably,the working characteristics of soft-switching can be improved,reducing system losses in the PS-FBC,enhancing the power supply efficiency of chargers for urban rail transit vehicles.Simulation results under various working conditions validate the effectiveness of the dead-zone time optimization design method.