箝位式三电平逆变器空间电压矢量调制方法的研究

本文论述了三电平中点箝位式逆变器SVPWM原理和实现方法，为了避免三电平逆变器在扇区切换中输出矢量突变，提出了一种首发矢量全部采用正小矢量或负小矢量的空间矢量调制算法，利用三个判断规则，可以很方便地确定出参考矢量所在的扇区和小三角形，给出了合成矢量的相应输出电压矢量，并推导了三角形顶点工作矢量的作用时间。通过检测负载电流方向和直流电容的电压，合理分配正负小矢量对的作用时间，实现了电容电压的平衡。仿真研究结果证实了本文提出的空间矢量调制算法的有效性。

A Study on SVPWM Method for Three-level Neutral-Point-Clamped Inverter

In this paper, SVPWM pattern and implement method is addressed for three-level Neutral-Point-Clamped(NPC) inverter. In order to avoid the abrupt change of output voltage vectors during the process of desired vector changing from one section to another, a novel space vector modulation (SVM) algorithm is proposed where positive or negative small vectors are adopted as first active vector, and it is convenient to determine which section and sub-triangle the desired vector is located by three judging rules. Also, output voltage vector to synthesize the desired vector is given and the duty time of active vectors for corresponding sub-triangle vertex is deducted. The neutral point potential stability is realized by detecting the direction of load current and neutral point voltage and design the real duty time of positive and negative space vectors in reason. Finally, the effectiveness of proposed SVM method is confirmed by simulative results.