纯电动汽车充电机输出阻抗特性

Research on BEV battery charger output impedance

纯电动汽车充电机与汽车动力电池构成级联式供电系统。充电机的输出阻抗是随频率变化的函数,动力电池也在不同频率下表现出不同的阻抗特性。为了在充电过程中充电机与动力电池组成的系统能够稳定工作,必须保证充电机输出阻抗与电池输入阻抗的比值满足奈奎斯特稳定性判据。以纯电动汽车充电机的输出阻抗为研究对象,建立充电机动态线性小信号模型,通过仿真分析输出阻抗特性随直流工作点,输出滤波器等效串联电阻,控制环路特性的变化规律,并用实验证明了理论分析的正确性,为充电机输出输出阻抗的设计提供了依据。

Battery electric vehicle（BEV） charger and auto power battery constitute a cascade power supply system. Charger＇s output impedance is function of frequency. Car power battery is also exhibit different impedance characteristics in different frequencies. In order to ensure the system to be stable, the ratio of the output impedance of charger and input impedance of the battery must meet the Nyquist stability criterion. This paper shows that when the BEV charger topology and main circuit parameters have been set, how other parameters such as input voltage, output current, equivalent series resistance （ESR） of output filter, crossover frequency and phase margin affect the BEV charger output impedance. Through simulation, with the input voltage, output current, ESR of output filter, crossover frequency and phase margin as running parameters, how closed-loop output impedance changes is found. Experimental results verify the theoretical analysis is correct.