On the sizing of fractional slot PM machines oriented towards the improvement of their torque production capability

Abstract

PurposeThe purpose of this paper is to propose an approach to improve the torque production capability of fractional slot permanent magnet machines.Design/methodology/approachFollowing an analytical formulation of the electromagnetic torque, two optimization criteria are selected: the maximization of the average torque and the minimization of the torque ripple. For the sake of a simple analysis, the proposed approach assumes that the effects of the machine circumferential and radial parameters, on the torque production capability, are almost decoupled, so that their sizing optimization could be carried out separately.FindingsThe torque production capability of the optimized machine has been confirmed by finite element analysis, which confirms the appropriateness of the proposed sizing approach.Practical implicationsThe obtained results should be validated by experiments carried out on a prototype.Originality/valueThe proposed approach has been carried out thanks to the introduction of the torque average value and ripple amplitude iso‐2D curves for circumferential parameters and iso‐3D surfaces for radial ones.