Methods of Improving Saliency in FSCW Synchronous Reluctance Machines

In Synchronous Reluctance Machines (SynRM), achieving a higher saliency ratio and lower torque ripple is important. While Fractional Slot Concentrated Winding (FSCW) machines have better efficiency because of shorter winding overhang, their saliency is significantly reduced due to the presence of undesirable magnetomotive force (MMF) space harmonics. Distributed windings (DW), on the other hand, have lesser torque ripple and higher saliency, but they suffer from lower efficiency because of their higher winding overhang. This paper presents methods of improving saliency by modifying the winding layout of FSCW which helps to reduce or eliminate certain undesired MMF harmonics, while achieving shorter overhang than distributed winding. In addition to saliency, various performance metrics including voltage distortion, efficiency, power factor, and torque ripple have been examined and compared with those of FSCW and distributed winding configurations.