This article proposes a four-degree-of-freedom overmodulation strategy for five-phase space vector pulsewidth modulation (SVPWM) in order to reduce the low-order harmonics of the output voltage during overmodulation. Based on the nearest-four-vector SVPWM algorithm, this overmodulation strategy calculates the corresponding third harmonic injection rate according to the modulation ratio in the overmodulation region. What is more, this strategy optimizes and controls the third harmonic so that basic voltage vectors of the fundamental wave subspace and the third harmonic subspace can be controlled simultaneously, thus effectively decreasing the low-order harmonic contents without reducing control degrees of freedom. The whole overmodulation region is divided into three subregions with linearized approximation to reduce the complexity of computation. Simulation and experimental results demonstrate that under the same modulation ratio during overmodulation, the proposed overmodulation strategy can improve the dc bus voltage utilization of a five-phase inverter, make the third harmonic controllable with four control degrees of freedom, and also reduce the low-order harmonic contents of the output voltage.

中文翻译：

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五相空间矢量脉宽调制的四自由度过调制策略

本文提出了一种用于五相空间矢量脉宽调制（SVPWM）的四自由度过调制策略，以减少过调制期间输出电压的低阶谐波。该过调制策略基于最近的四矢量SVPWM算法，根据过调制区域中的调制比来计算相应的三次谐波注入速率。而且，该策略优化并控制了三次谐波，从而可以同时控制基波子空间和三次谐波子空间的基本电压矢量，从而在不降低控制自由度的情况下有效地降低了低次谐波含量。整个过调制区域被划分为三个具有线性近似的子区域，以降低计算的复杂性。