电压不平衡条件下电动汽车充电机电流分析模型

Electric Vehicle Charger Current Analysis Model under Unbalanced Voltage

电网运行过程中,三相负载不平衡、线路参数不对称及不对称故障等因素均可能引起三相电压不平衡。不平衡电压作用下,电动汽车充电机输入电流将存在完全断续、完全连续及混合状态等不同续流状态。为精确且全面地描述电动汽车充电机在电压不平衡条件下的输入电流特性,以三相电流续流状态为依据,提出不平衡条件下涵盖全部运行范围的充电机运行状态划分方法;以此为基础,充分考虑网侧电压不平衡分量与谐波分量影响,建立包含无源功率因数校正环节、线路等效阻抗及交流侧滤波电感的充电机不同运行状态对应电流分析模型。理论计算与实验结果证明了所提模态划分方法的有效性和所提建模方法的精确性。

In the process of grid operation,unbalanced three-phase load,asymmetric line parameters and asymmetric fault may cause unbalanced three-phase voltage.With the influence of unbalanced voltage component,the input current of electric vehicle charger has different operation modes,including completely discontinuous state,completely continuous state and intermediate mixed state.In order to accurately and comprehensively describe the input current characteristics of the electric vehicle charger under the condition of voltage imbalance,according to the difference of three-phase current state,a method of operating state division covering all operating conditions of the charger is proposed.Considering the influence of unbalanced voltage component and harmonic component,the current analysis models of charger in different modes,including passive power factor correction section,line equivalent impedance and AC filter inductance,are established respectively.By comparing the theoretical calculation waveform of the proposed model with the measurement results of physical experiments,the validity of the proposed modal division method and the accuracy of the proposed model are verified.