A novel technique for minimizing torque ripple in axial flux segmented rotor SRM

Axial flux machine is an attractive option for in-wheel electric vehicle (EV) application, which requires high ratio of outer diameter to axial length. Further, utilization of lamination material in axial flux machines is better than that of radial flux machines. In order to reduce cost, magnet-less machines are desirable. In view of all these factors a single-stator, dual-rotor, three-phase axial flux segmented rotor switched reluctance motor (AFSSRM) with toroidal windings was recently proposed [1]. It was observed that torque ripple is high in this machine. In this paper, a simple and effective technique to reduce torque ripple in AFSSRM is proposed. Two rotors of AFSSRM are circumferentially displaced with respect to each other. It is analytically proved that torque ripple can be reduced using this technique. This is also verified by finite element method (FEM) analysis based simulation studies. It is observed that the torque ripple is reduced by 54.6%. Effect of rotor displacement on axial attraction forces is also discussed.