Design Modification in Single-Tooth Winding Double-Stator Switched Reluctance Motor for Torque Ripple Mitigation

Double-stator switched reluctance motors (DSSRMs) with single-tooth winding topology possesses high torque density when compared to conventional switched reluctance motors (SRMs). However, their inherent high torque ripple is still an issue for industrial applications. In SRMs, the torque shared by the outgoing phase reduces significantly in the commutation region. However, at the same time, the incoming phase does not achieve sufficient torque generation. This results in a high torque ripple in this region. In this paper, several design procedures are discussed to improve the performance of the radial flux DSSRM with single-tooth winding topology. Firstly, the pole arc equations of stator pole and rotor segments for the higher difference between aligned and unaligned inductance are derived for high output torque and based on this, the selection of the number of stator slots/rotor segments is discussed. Furthermore, the influence of winding polarities on the core loss and output torque of DSSRM is discussed. Finally, the design modification in rotor structure is proposed with an angular shift in the alternate rotor segments in the direction of rotation to mitigate the torque ripple. To investigate the effectiveness of the proposed design modification, a finite-element model of a 3-phase 12/10/12 pole radial flux DSSRM is developed in ANSYS/MAXWELL software, and simulation results are presented. It is observed that a 40% reduction in the torque ripple is achieved in the case of the proposed motor. The proposed design modification improves the torque generating capability of the incoming phase in the commutation region, which reduces the torque dip in this region and subsequently reduces the torque ripple.