Analytical model for the minimization of torque ripple in permanent magnets assisted synchronous reluctance motors through asymmetric rotor poles

Abstract

Synchronous Reluctance motor has recently gained popularity in applications where induction motors are normally employed. Additionally, when permanent magnets are buried in the rotor, they become an alternative for high performance applications. Some of its drawbacks such as high torque ripple and low power factor need to be overcome. The design of Synchronous Reluctance motors with asymmetric flux barriers has been recently used to reduce torque ripple. Finite element models are necessary tool to find the right place and dimensions of the flux barriers as well as to predict the torque harmonics. However, it is time consuming to analyze the model since periodicity and symmetry conditions cannot be used to reduce the model to a single pole. Therefore, in this paper an analytical model is presented to rapidly and accurately study the effect of such asymmetry of rotor poles on the torque ripple. The proposed approach is developed for symmetrical and asymmetrical geometries and validated against finite element models.