A novel high torque and low weight segmented switched reluctance motor

Switched reluctance motors (SRM) have advantages of low manufacturing cost, rugged and simple construction and lesser switches in drive circuit. However, some of its disadvantages are noise, torque ripple and low torque per unit volume. A few of these limitations, such as noise and low torque to volume have been mitigated in the segmented switched reluctance machine (SSRM), which uses a full-pitched winding. It is established that SSRM can give upto 40% more torque than variable reluctance switched reluctance motor (VRSRM) for the same frame size. In this paper, it is proved that if magnetic circuit of SSRM is operated in the linear region of the B-H curve there is further increase in the torque. But this results in an increase in the active weight of iron because of the higher stator yoke thickness required for this purpose. In this paper, a novel segmented switched reluctance machine is proposed. This machine has circular slots in the stator and henceforth will be referred to as circular slot segmented switched reluctance machine (CSSSRM). In CSSSRM, flux in the stator and rotor is forced to follow a circular path, thereby increasing the average torque and reducing the iron used as compared to VRSRM and SSRM. The effect of the variation in geometric parameters on the average torque is examined through finite element analysis. Comparison of CSSSRM with VRSRM and SSRM is also carried out. For the same frame size it is found that the increase in torque over VRSRM is about 62% when the magnetic circuit is operated in the linear region of the B-H curve. Further, Volt-Ampere rating of CSSSRM is predicted.