一种基于矢量空间解耦的三电平六相逆变器空间矢量调制策略

Design of a Space Vector Modulation Strategy Based on Vector Space Decomposition for Three-Level Six-Phase Inverters

以中压大功率交流电机驱动为背景,提出一种新型基于矢量空间解耦(VSD)的六相中点钳位型(NPC)三电平空间矢量调制策略(SVM)。其原理为:采用VSD矩阵将六维变量解耦并映射到3个二维平面,即α-β平面、x-y平面及o1-o2平面,提出矢量精简原则使矢量数量从729个简化到417个,进而设计最优五矢量法(OFV)消除x-y平面的谐波电压。同时,提出区域投影法提高了参考矢量位置判断效率,并以冗余负矢量作为首发矢量的矢量作用顺序有效平衡了直流侧中点电位。最后通过实验验证了上述策略的有效性。

This paper presents a novel space vector modulation（ SVM） strategy based on vector space decomposition（ VSD） for neutral point clamped（ NPC） three-level six-phase inverter,which could be used in medium-voltage high-power AC electric drives. The principle is given as follows. The six-dimensional variables are decoupled and mapped into three two-dimensional spaces,namely the α-β space,the x-y space and the o1-o2 space. A vector simplified principle is proposed to reduce the number of the original vector from 729 to 417. Then the optimal five vectors（ OFV） technique is designed to eliminate harmonic voltage in the x-y space. Meanwhile,the method of the region projection is proposed to improve thejudgment efficiency of the voltage reference vector in the complex region. The optimal vector operational order, by using the redundant negative vector as the first operation vector, balances the neutral point voltage effectively. Finally, the experimental resultsare given to verify the above mentioned theoretical developments.