多电平逆变器通用电容电压平衡优化算法

摘要

针对二极管箝位型多电平逆变器电容电压难以控制的问题，分析了一种简单的多电平逆变器等效模型，用于预测结点电压偏差，提出了一种多电平逆变器电容电压平衡优化SVPWM ( space vector pulse width modulation)算法。该算法通过预测不同开关状态下直流侧结点电压偏差，建立目标函数并对其寻优，在每个开关周期选取最优的开关组合达到结点电压平衡。理论分析和试验结果表明，该算法适用于任意电平逆变器电容电压平衡的控制，解决了三电平逆变器电容电压平衡的问题，但在三电平以上的逆变器受调制度限制。针对三电平以上高调制度下电容电压失衡的原因进行了分析，并给出了解决方法。仿真和实验验证了算法的正确性。%Capacitor voltages of diode clamped multilevel inverters are hard to control. In order to solve this problem,a simple equivalent circuit of multilevel inverters to predict the deviation of node voltages was analyzed, and an optimization algorithm of space vector pulse width modulation( SVPWM) for capaci-tor voltage balance of diode clamped multilevel inverters was presented. This algorithm predicts the devia-tion of node voltages for different operation modes to develop an optimization algorithm to minimize the voltage deviation among different capacitors. In this algorithm the best switch combinations were selected during each switching cycle to reach node voltage balance. Theoretical analysis and experimental results show this algorithm is naturally applicable to inverters with an arbitrary number of levels. Capacitor volta-ges of three-level inverter are controlled, but more than three-level inverter system is restricted by the modulation. For more than three-level system, the cause of capacitor voltage imbalance under high modu-lation was analyzed, and a solution was presented. Simulation and experimental results verify the correct-ness of this algorithm.