中點電位不平衡度反饋的三電平虛擬空間矢量調制方法

向超群 陳春陽 韓丁 成庶

摘 要：中點電位不平衡是中點箝位型三電平逆變器的固有問題。提出了一種基于中點電位不平衡度反饋的虛擬空間矢量調制方法，考慮到中點電位偏移時小矢量和中矢量的變化，對三電平空間矢量進行重新分區，構造虛擬矢量。引入中點電位不平衡度，根據中點電位偏移方向和相電流的方向，選擇有利于平衡中點電位的小矢量，合理安排矢量序列，實現對中點電位的精確控制。提出的控制算法能在全調制度下消除中點電位的低頻波動，有效治理中點電位偏移，開關損耗低，動態性能好。仿真和實驗研究驗證了算法的有效性。

關鍵詞：三電平中點箝位逆變器，虛擬空間矢量調制，中點電位平衡，不平衡度

DOI：10.15938/j.emc.（編輯填寫）

中圖分類號： TM 464 文獻標志碼：A 文章編號：1007 -449X（2018）00-0000-00（編輯填寫）

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