This article presents a carrier-based pulsewidth modulation (PWM) strategy to reduce the common-mode voltage (CMV) with output harmonic distortion minimization for three-level neutral-point-clamped (NPC) inverters. The proposed method is first presented for three-level NPC inverters, and then, generalized for odd n-level inverters including NPC and cascaded inverters. With the help of base voltage vectors, the odd n-level space vector diagram can be transformed into a two-level one on which the modulation analysis is conducted This strategy utilizes two zero CMV vectors and one virtual vector, which is the combination of two other vectors with equal duty-split cycle, thereby, reducing the CMV magnitude and suppressing low-frequency components of the CMV. The construction of space vector diagrams with virtual vectors leads to three switching sequences in which one switching sequence gives the best harmonic performance under the harmonic distortion analysis, thereby significantly reducing the output harmonic distortion. Therefore, the proposed reduced CMV PWM strategy achieves zero average CMV in one switching period, and minimized output harmonic distortion in comparison to the existing methods. Simulation and experimental results confirm the effectiveness of the proposed strategy.

中文翻译：

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三电平中性点钳位逆变器输出谐波失真最小的减共模电压脉宽调制方法

本文介绍了一种基于载波的脉宽调制 (PWM) 策略，用于降低共模电压 (CMV)，同时最小化三电平中性点钳位 (NPC) 逆变器的输出谐波失真。所提出的方法首先针对三电平 NPC 逆变器提出，然后推广到包括 NPC 和级联逆变器在内的奇数 n 级逆变器。借助基极电压矢量，可以将奇数 n 级空间矢量图转化为两级空间矢量图，对其进行调制分析 该策略利用两个零 CMV 矢量和一个虚拟矢量，它是两者的组合其他具有相同占空比的矢量，从而降低 CMV 幅度并抑制 CMV 的低频分量。用虚拟向量构建空间矢量图导致三个开关序列，其中一个开关序列在谐波失真分析下给出最佳谐波性能，从而显着降低输出谐波失真。因此，与现有方法相比，所提出的缩减 CMV PWM 策略在一个开关周期内实现了零平均 CMV，并最小化了输出谐波失真。仿真和实验结果证实了所提出策略的有效性。与现有方法相比，输出谐波失真最小。仿真和实验结果证实了所提出策略的有效性。与现有方法相比，输出谐波失真最小。仿真和实验结果证实了所提出策略的有效性。