Variations in overall developed torque of a switched reluctance motor with airgap nonuniformity

In this paper, the results of a two-dimensional finite element analysis conducted on an 8/6 switched reluctance motor for studying the effects of airgap nonuniformity on the overall developed torque profiles are presented. Effects of nonuniform airgap produced by the relative eccentricity between the stator and rotor axes, concentricity error in the rotor geometry on one half, and also the motor with an elliptical rotor, are presented. It is observed that with the increase in relative eccentricity or positive concentricity error, the average torque increases along with an increase in the ripple content. In case of relative eccentricity, the static torque characteristics for the different phases will be different resulting in more noise and vibration of the system.