Torque profiles of a switched reluctance motor having special pole face shapes and asymmetric stator poles

In this paper, the results of a finite-element (FE) analysis carried out on an 8/6 switched reluctance motor (SRM) having special pole face shapes, such as: 1) noncircular stator pole face with varying airgap under a pole; 2) flat topped rotor pole faces; and 3) noncircular airgap caused by elevated rotor poles, are presented. Apart from this, the case of an asymmetrical centering of a stator pole is also analyzed. The analysis has revealed that the motor with noncircular stator pole face gives higher average torque. Thus, for motors intended for operation in one direction only, such noncircular airgap is preferred. In case of flat topped rotor poles, the average torque reduces drastically. The rotor poles projected slightly outward on one side with corresponding decrease in pole heights in the stator pole will create airgap with varying mean diameters under a pole pair. This configuration of the motor poles results in more average torque with high torque ripple. The case of the motor with one of the stator pole shifted by an angle from the center keeping the stator bore diameter constant is also analyzed. It is observed that the average as well as the maximum torque produced by the motor decreases with the increase in shift in either direction.