中点电位不平衡度反馈的三电平虚拟空间矢量调制方法

向超群 陈春阳 韩丁 成庶

摘 要：中點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。

关键词：三电平中点箝位逆变器，虚拟空间矢量调制，中点电位平衡，不平衡度

DOI：10.15938/j.emc.（编辑填写）

中图分类号： TM 464 文献标志码：A 文章编号：1007 -449X（2018）00-0000-00（编辑填写）

Abstract： Neutral-point potential unbalance is an inherent drawback of neutral point clamped three-level inverter. An virtual space vector pulse-width modulation based on the neutral point potential unbalance degree feedback is proposed in this paper. 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 is introduced. According to the direction of neutral point potential drift and phase current，select the small vector which is advantageous to balance neutral point potential and arrange appropriate vector sequence， and then accurately control neutral point potential. This algorithm can effectively regulate neutral point potential drift and eliminate low frequency voltage oscillation under whole modulation degree. The method has good dynamic performance and low switching loss . The effectiveness of the algorithm is verified by simulation and experimental investigation.

Keywords： three-level neutral point clamped inverter， virtual space vector modulation， neutral point potential balance， unbalance degree