Fractional slot-winding with asymmetrical stator slot-layout

The paper presents the application of a single-layer fractional slot winding in order to reduce low-order harmonics in small permanent-magnet ac-machines. This approach allows the geometry to be kept simple, i.e. having a small number of stator slots whilst achieving good winding-factors. This winding-layout requires an uneven number of stator-slots with different slot-sizes. The paper introduces the winding concept, addressing benefits and drawbacks and compares it to standard and single-teeth windings