SPM Machine with Reduced Loss and Cogging for Wide-Speed Operating Range

This paper proposes a cost effective, better efficient inset magnet solution for the surface mounted permanent magnet (SPM) motor that suits low speed applications. The pole arc angle of the permanent magnet (PM) is reduced by 30% and the vacant volume is filled with silicon steel laminations to introduce saliency within the PM machine. The machine losses are computed and the efficiency of the proposed motor is compared with an existing outer rotating PM motor with a wide pole arc angle (180° elec.) over the entire torque-speed operating range. The increase in the cogging because of the added saliency is reduced with the introduction of single/ multiple grooves on the stator teeth.