共交流母线电动汽车充放电系统小信号建模及稳定性分析

Small-Signal Modeling and Stability Analysis of Charging and Discharging System of Electric Vehicles with Common AC Bus

在非理想电网条件下,对共交流母线充放电系统的小信号建模和稳定性分析进行深入研究。首先,基于dq轴线性化方法,建立了考虑电压环、电流环及锁相环(phase locked loop,PLL)影响的三相AC/DC变换器交流输入阻抗矩阵,并对阻抗特征及影响因素进行深入分析。其次,基于广义奈奎斯特判据(gneralized Nyquist criterion,GNC),推导出充放电系统的降阶阻抗稳定性判据;再次,分别从充电和放电角度,以定性和定量的方式给出了系统可稳定接入的最大充放电功率,用于指导系统的参数设计。最后,通过理论分析和仿真验证,证明了所建立的dq坐标系阻抗模型、稳定判据及稳定性分析结论的正确性。

Under weak grid,the small-signal modeling and stability analysis of the common AC bus charging and discharging system are deeply studied.Firstly,by d-q axis linearization,the AC input impedance matrix of the three-phase AC/DC converter considering the influence of voltage loop,current loop and phase locked loop(PLL) is established,and the influencial factors of impedance characteristics and stability are analyzed in depth.Secondly,according to the Generalized Nyquist Criterion(GNC),the reduced-order impedance stability criterion of the charging and discharging system is derived.Finally,from the perspective of charging and discharging,it is given in a qualitative and quantitative manner.With the stability analysis,this paper gets the maximum charge and discharge power,and the conclusion can be used to guide the parameter design of the system.Through theoretical analysis and simulation verification,the correctness of the impedance model in d-q coordinate system,stability criterion and stability analysis conclusion established in this paper are obtained.