Multilevel multi-phase propulsion drives

This paper presents a comprehensive analysis of the 5-phase induction motor driven by voltage-source inverter drives and particularly its steady-state performance evaluation. The performance of various modulation methods are analyzed with insightful look into their harmonic content and torque ripple. Three separate methods are proposed to reduce the torque ripple for low, middle and high modulation index regions while eliminating or controlling the non-torque-producing harmonics within the current machine rating. A complete set of simulations are carried out to verify the concepts and proposed methods. The multi-level multiphase topology is introduced and it is compared to the two-level system. The modification of switching sequence for reduction of torque ripple is applied to the three-level 5-phase motor drive. Application of the multilevel multi-phase concept to high power motor drives (as well as motor design and selection) is discussed.