电流频谱可控的单相并网逆变器模型预测控制方法

Model Predictive Control Method With a Controllable Current Spectrum for Single Phase Inverter

提出一种应用于单相并网逆变器的电流频谱可控的模型预测控制方法。该方法基于单相并网逆变器的离散状态模型,利用当前系统状态检测量预测下一时刻的并网电流值;然后将并网电流预测值和给定值的差值设置为指标函数,对所有电压矢量进行评估,选取可使指标函数最小的电压矢量;最后根据该电压矢量反推出逆变器的开关信号来控制逆变器下一时刻的输出,从而实现并网电流最优控制效果。为改善并网电流的频谱,在指标函数中加入数字滤波器。这种控制方法物理模型清晰、数字化控制易于实现;与传统的控制方式相比,不用整定PI参数,且系统具有较强鲁棒性。仿真结果表明控制器对并网电流跟踪性能良好,电流频谱分析显示出开关频率近似恒定的控制效果。

This paper presents a model predictive control method with a controllable current spectrum applied to single phase grid-connected inverter.The method can predict the future value of the grid current by using the detection value of the current state based on the discrete-time model of a single phase grid-connected inverter;then takes the difference value between the predictive value and given value of grid current as a objective function,evaluates all voltage vectors and selects the voltage vector which minimizes the objective function;finally,uses the switch single deduced by the voltage vector to control the next output of single phase inverter,which can achieve the optimal control effect of grid current.In order to improve the frequency spectrum of grid connected current,a digital filter is added to the objective function.The method is easy to realize digital control and its physical model is distinct.It does not adjust the PI parameters and has a strong robustness compared with the traditional control method.The simulation results show that the controller has good tracking performance for grid current,and the control effect is similar to the constant switching frequency by current spectrum analysis.