摘要
A control strategy of repetitive control without inductorance decoupling was proposed to address the problem of high total harmonic distortion(THD)rate of the network-side current caused by the reduced stability of the rectifier module of the DC charging pile under weak grid as well as the dead zone and nonlinearity of switching devices during charging.Firstly,the parallel repetitive control was constructed in the inner current loop,and the proportional-integral(PI)+repetitive controller based on parallel structure was designed.For system compensation,a second-order low-pass filter was selected to correct the system,and the network-side current harmonics were actively suppressed without increasing the filtering device,which effectively improves the quality of grid-connected current.Secondly,based on the synthetic vector method,the controller parameters were designed to realize the elimination of main pole by establishing two synchronous rotation coordinate system vector differential equations,so as to realize the inductanceless decoupling to cope with the influence of network-side inductance fluctuation on the stability of the control system under weak grid.By theoretical analysis and simulation,the proposed control strategy was embedded into the self-developed digital signal processor for the rectifier module of DC charging pile,simulated dynamic and steady-state operation experiments were conducted,and comparative analysis was performed to prove the feasibility of the proposed control strategy.
针对直流充电桩整流模块在弱电网下稳定性降低,充电过程中开关器件死区和非线性等导致的网侧电流总谐波畸变率较高的问题,提出了重复控制结合无电感参数解耦方法的电压型整流器(Voltage source rectifier,VSR)控制策略。首先,在内环电流构造并联重复控制,设计了基于并联结构的比例积分控制(Proportional-integral,PI)+重复控制器,并针对补偿环节,选取二阶低通滤波器对系统进行校正,在不增加滤波装置的情况下,主动抑制网侧电流谐波,有效提高并网电流质量。其次,基于合成矢量法,建立两相同步旋转坐标系矢量微分方程,设计控制器参数进行主极点对消,从而实现无电感参数解耦,以应对弱电网下网侧电感波动对控制系统稳定性的影响。在理论分析和仿真实验的基础上,将所提出的控制策略嵌入自主开发的直流充电桩整流模块数字信号处理器,模拟动态和稳态运行实验,并进行对比分析。实验结果证明了该控制策略的可行性。
基金
supported by National Natural Science Foundation of China(No.61903291)
Shaanxi Province Key R&D Program(No.2022GY-134)。
