Design of Single-Layer Fractional-Slot Distributed Windings

Besides the usual winding design method based on the star of slots, the winding index is proposed in this article. In compliance with the presented counterexamples, it can be shown that the star of slots is unable to design most of single-layer fractional-slot distributed windings. In some restricted cases, it is possible to apply the introduced additional step to extract the winding layout from the double-layer fractional-slot distributed winding for the same number of phases, number of slots and number of pole pairs. Generally, the winding index can be applied to design symmetrical windings such as single-layer fractional-slot distributed windings and windings with a variable zone width. However, a systematic design procedure based on the winding index has not yet been suggested in literature, which is the focus of this article.