This article proposes a modeling approach and an optimization strategy to exploit a third-harmonic current injection for the torque enhancement in multiphase isotropic permanent magnet synchronous machines with nonsinusoidal back electromotive forces. The modeling approach is based on a proper vector space decomposition and on the associated rotational transformation, aimed to properly select a set of stator current space vectors to be controlled. It is presented for a generic (i.e., asymmetrical, with an arbitrary angular shift) winding configuration. The injection strategy is related to the choice of a constant synchronous current set aimed at minimizing the average stator winding losses for a given reference torque by using the first and the third spatial harmonics of the air-gap flux density. The optimal solution has been found analytically and has been developed in detail for a selected set of asymmetrical winding configurations. Both the numerical and experimental results are in good agreement with the theoretical analysis.

中文翻译：

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非对称多相永磁同步电机的最优三次谐波电流注入


本文提出了一种建模方法和优化策略，以利用三次谐波电流注入来增强具有非正弦反电动势的多相各向同性永磁同步电机中的扭矩。该建模方法基于适当的向量空间分解和相关的旋转变换，旨在正确选择一组要控制的定子电流空间向量。它是针对通用（即，不对称，具有任意角度偏移）绕组配置而提出的。注入策略与恒定同步电流组的选择有关，旨在通过使用气隙磁通密度的第一和第三空间谐波来最小化给定参考扭矩的平均定子绕组损耗。通过分析找到了最佳解决方案，并针对一组选定的不对称绕组配置详细开发了最佳解决方案。数值和实验结果均与理论分析吻合良好。