基于改进模型预测单相三电平变换器控制研究

摘要

单相三电平变换器广泛应用于高速铁路驱动系统.但是三电平变换器存在中点电位不平衡问题,为此,提出一种模型预测控制,通过选择矢量实现中点电位平衡.首先对模型预测控制进行建模.然后通过价值函数选择最优矢量,实现电流跟踪控制.该方法和传统PI控制器相比,不需要参数调节和矢量调制技术;且和PI控制器相比,该方法具有更快的跟踪速度.和传统的模型预测控制相比,该方法不需要调节复杂的权重系数.通过实验验证了所提出方法能够很好地跟踪给定电流,而且中点电位也得到很好的控制.%A single-phase three-level converter is widely used in high railway electric traction system.However, the three-level converter exist the neutral-point voltage unbalance.Therefore,a model predictive control method was proposed. The neutral-point voltage could be balanced by selecting the vectors. First of all,the model was used for model predictive control.Then the vector could be chosen by selecting the optimal value function to realize the current tracking control.Compared with traditional PI controller,this method did not need parameter adjustment and vector modulation technology. And compared with PI controller,the method had faster tracking speed. Compared with the conventional model predictive control,the proposed method did not need to adjust the complex weighting coefficients. Experiments validate that the proposed method can track the given current well,and the neutral-point voltage is well controlled.