共模电压减小的五电平ANPC快速模型预测控制

Fast Model Predictive Control With Common-mode Voltage Reduction for Five-level ANPC

针对三相五电平有源中点箝位型(ANPC)逆变器共模电压和电容电压平衡问题,提出了一种具有共模电压减小的快速模型预测控制(MPC)策略。首先,通过建立变换器输出共模电压的数学模型,舍去对共模电压影响较大的电压空间矢量,有效抑制了共模电压的脉动;在此基础上通过扇区划分,减少了控制集内的电压矢量数;然后根据悬浮电容电压采样值选择合适的开关状态,控制了悬浮电容电压的平衡。最后,将负载电流和上、下直流母线电容电压值作为预测模型的输入,选择价值函数最小的开关状态作为控制器的输出。此方法在平衡电容电压和减小共模电压脉动的基础上,降低了价值函数构建的复杂性,减小了控制器的计算量,提高了计算效率。

In order to solve the problems of common-mode voltage and capacitor voltage balance for three-phase five level active neutral-point-clamped(ANPC)converter,a fast model predictive control(MPC)strategy is proposed to reduce the common mode voltage.Firstly,the mathematical model of the output common mode voltage of the converter is established,the space vector of voltage which has great influence on the common mode voltage is abandoned to suppress the fluctuation of the common mode voltage effectively.Based on this,the number of voltage vectors in the control set is reduced by sector division.Then,floating-capacitor voltages are balanced by selecting the switching state appropriately according to the voltage sampling value of the suspended capacitor.Finally,the load current and the capacitance voltage of the upper and lower DC buses are used as the inputs of the prediction model,and the switching state with the minimum value function is selected as the output of the controller.On the basis of balancing capacitor voltage and reducing common mode voltage ripple,not only the complexity of constructing the value function is greatly reduced,but also the amount of calculation of controller is well reduced,and the method improves calculation efficiency.