The output performance of three-level inverters will be deteriorated under two-phase loads condition if conventional discontinuous PWM (DPWM) strategies are adopted. To solve the above issue, the amplitude and the phase angle of basic voltage vectors are modified in this article. Accordingly, sectors and triangles of the space vector diagram are reconsidered, duty cycles of basic vectors synthesized the reference vector are recalculated. And then four types of DPWM applicable for two-phase load are put forward. Although the harmonic distortion of the output waveform is reduced, discontinuous intervals are not optimum distributed. To further improve the output waveform quality, the amplitude of average current ripple vector is introduced as the evaluation index to redistribute discontinuous intervals of phase voltage in each fundamental period. Then, a hybrid DPWM strategy is presented and the harmonic distortion of the output waveform is minimized. Meanwhile, the neutral-point voltage ripple and the switching loss are also suppressed. The effectiveness of the hybrid DPWM strategy is verified by both simulation and experimental results.

中文翻译：

---

两相负载条件下三电平逆变器的混合非连续空间矢量PWM策略


如果采用传统的不连续脉宽调制（DPWM）策略，三电平逆变器的输出性能在两相负载条件下将会恶化。为了解决上述问题，本文对基本电压矢量的幅值和相位角进行了修改。相应地，重新考虑空间矢量图的扇形和三角形，重新计算与参考矢量合成的基本矢量的占空比。进而提出了适用于两相负载的四种DPWM类型。虽然输出波形的谐波失真减少了，但不连续间隔的分布并不是最佳的。为了进一步提高输出波形质量，引入平均电流纹波矢量幅值作为评价指标，对各基波周期内相电压不连续区间进行重新分配。然后，提出了一种混合DPWM策略，最小化了输出波形的谐波失真。同时，中性点电压纹波和开关损耗也得到抑制。仿真和实验结果验证了混合DPWM策略的有效性。