单相准Z源逆变器改进模型预测控制策略

Improved Model Predictive Control Strategy for Single-phase Quasi Z-source Inverter

传统模型预测控制(MPC)应用于准Z源逆变器(qZSI)中存在控制变量误差较大的问题,导致工频电流纹波增加,电能质量恶化。因此,此处提出一种基于电流电压纹波双前馈的改进MPC策略。首先分析系统在不同模态下的工作原理,构建离散状态模型;其次计算输出电流和电容电压在各状态下的纹波,通过双前馈迭代生成新参考值,并采用两步预测法对系统的执行滞后周期予以补偿,以增强电流和电压的控制效果;然后对代价函数综合排序,合理选择最优矢量,避免了权重系数的试凑,进一步增强变量之间的协同控制。最后,实验结果表明,系统具有良好的动、稳态性能,验证了改进策略可行、有效。

Traditional model predictive control(MPC)applied to quasi Z-source inverter(qZSI)has the problem of la-rge control variable error,which leads to the increase of power frequency current ripple and deterioration of power quality.Therefore,an improved MPC strategy is proposed based on double feedforward of current and voltage ripple.Firstly,the working principle of the system in different modes is analyzed,and the discrete state model is built.Sec-ondly,the ripple of output current and capacitor voltage in each state is calculated,and a new reference value is generated by double feedforward iteration.The two-step prediction method is used to compensate the execution lag pe-riod of the system to enhance the control effect of current and voltage.Then,the cost function is comprehensively ranked,and the optimal vector is reasonably selected to avoid the trial and error of weight coefficients and further en-hance the collaborative control between variables.Finally,the experimental results show that the system has good dy-namic and stable performance,and the improved strategy is feasible and effective.