Assessment and exploitation of the minimum current harmonic distortion under overmodulation in five-phase induction motor drives

Abstract

This paper compares the most prominent overmodulation (OVM) techniques for five-phase induction motor drives with respect to the minimum current distortion (MCD) achievable. To attain a benchmark of the latter, two MCD OVM approaches are devised. Contrarily to previous strategies aimed at voltage distortion reduction/minimization, these MCD methods are focused on minimizing the harmonic stator copper loss (HSCL), thus minimizing the current total harmonic distortion (THD). One of these MCD strategies minimizes the HSCL while injecting only x–y harmonics. The other MCD method exploits α–β harmonic injection to further decrease the HSCL and to cover the whole OVM region. Moreover, the dual-mode OVM, which is one of the three-phase methods with the lowest distortion, is extended here for five-phase drives. The findings provide insight into how close the OVM methods are to the benchmark imposed by the MCD strategies. Notably, these MCD techniques yield a significant reduction of current THD, HSCL and peak current, especially for machines with negligible thirdorder space harmonic. The average switching losses are also decreased. Indications for real-time implementation of the MCD solutions are also given