Multiphase permanent magnet synchronous motors with fractional slot windings: The future of low speed drives?

Abstract

Purpose

The purpose of this paper is to investigate advantages of multiphase permanent magnet synchronous motors (PMSM) with fractional slot concentrated windings (FSCW). The investigation is based on comparative analysis and assessment of FSCW PMSM wound as 3, 6, 9 and 12 phase machines suited for low speed applications.

Design/methodology/approach

The investigations are focussed on distortions of back electromotive (emf) and magnetomotive force (mmf) with the torque ripples and motors’ performance taken into account. The finite element models with the aid of customized computer code have been adopted for motor winding design and back emf, mmf and motor performance analyses.

Findings

The novel multiphase winding layouts were found to offer lower content of sub-harmonics in the mmf waveforms compared with the traditional three-phase machine designs. Moreover, the investigated multiphase machines exhibited higher average value of the electromagnetic torque, while the multiphase PMSM machines with FSCW were further characterized by significantly lower torque pulsations.

Originality/value

The analyses presented in this paper demonstrate that PMSM with FSCW are advantageous to their counterpart three-phase machines. Specifically, they offer higher performance and are more suitable to work with multiple drives supplying segmented winding system. This ability of using multi-drive supply for one motor offers flexibility and cost reduction while increasing fault tolerant power train system.

Citation

Jedryczka, C., Szelag, W. and Piech, Z.J. (2016), "Multiphase permanent magnet synchronous motors with fractional slot windings: The future of low speed drives?", COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Vol. 35 No. 6, pp. 1937-1948. https://doi.org/10.1108/COMPEL-03-2016-0120