三相四桥臂并网逆变器的无差拍重复控制

为提高三相四桥臂并网逆变器的动、静态特性,采用改进无差拍控制内置重复控制器的复合控制方法对并网电流进行控制。无差拍电流控制能够快速准确地跟踪给定信号,基于内模原理的重复控制通过在基频及其整数倍频处提供高增益可快速消除每一周期的稳态误差。根据电压型三相四桥臂并网逆变器的数学模型,推导了无差拍控制算法,并分析了无差拍控制中的控制延时对系统稳定性的影响;内置的重复控制器能改善无差拍控制对电感参数敏感的缺陷并降低算法对模型精确度的依赖,从而消除周期性稳态误差,通过对模型传递函数的分析,得到重复控制器的最佳补偿拍数。仿真和实验结果表明,所提出的控制策略能实现对参考电流的快速准确跟踪。

Deadbeat and Repetitive Control for Grid-connected Three-phase Four-leg Inverters

A combined control scheme of improved deadbeat control and plug-in repetitive control is proposed for grid-connected three-phase four-leg inverters to control the grid-connected current. The deadbeat current control can quickly and accurately track a given signal, and the repetitive control based on the internal model principle can quickly eliminate the steady-state error in each cycle by providing high gain at the fundamental frequency and its integral multiples. Based on the mathematical model of grid-connected voltage-type three-phase four-leg inverter, the deadbeat control algorithm is derived, and the effect of control delay in the deadbeat control on the stability of the system is analyzed. The plug-in repetitive controller is able to reduce the sensitivity of the deadbeat control to the inductance parameters and the dependence on the model accuracy. Thus, the periodic steady-state error can be eliminated. The optimal compensation step is obtained by analyzing the transfer function of the model. Finally, the simulation and experimental results show that the proposed control strategy can achieve fast and accurate tracking of the reference current.