中点电位不平衡度反馈的三电平虚拟空间矢量调制方法

摘要

Neutral-point potential unbalance is an inherent drawback of neutral point clamped three-level inverter.Anvirtual space vector pulse-width modulation based on the neutral point potential unbalance degree feedback was proposed.Taking into account the change of small vectors and middle vectors when neutral point potential unbalance occurs,the proposed solution repartitions space vector sectors of the three-level inverter and constructs virtual vector.The neutral point potential unbalance degree was intro-duced.According to the direction of neutral point potential drift and phase current,the small vector was selected which is advantageous to balance neutral point potential and arrange appropriate vector se-quence,and then neutral point potential was controlled accurately.This algorithm can effectively regulate neutral point potential drift and eliminate low frequency voltage oscillation under whole modulation de-gree.The method has good dynamic performance and low switching loss.The effectiveness of the algo-rithm is verified by simulation and experimental investigation.%中点电位不平衡是中点箝位型三电平逆变器的固有问题.提出了一种基于中点电位不平衡度反馈的虚拟空间矢量调制方法,考虑到中点电位偏移时小矢量和中矢量的变化,对三电平空间矢量进行重新分区,构造虚拟矢量.引入中点电位不平衡度,根据中点电位偏移方向和相电流的方向,选择有利于平衡中点电位的小矢量,合理安排矢量序列,实现对中点电位的精确控制.提出的控制算法能在全调制度下消除中点电位的低频波动,有效治理中点电位偏移,开关损耗低,动态性能好.仿真和实验研究验证了算法的有效性.