Quantitative Comparison for Fractional-Slot Concentrated-Winding Configurations of Permanent-Magnet Vernier Machines

This paper compares the fractional-slot concentrated-winding (FSCW) configurations of permanent-magnet vernier (PMV) machines. The representative three-phase FSCW PMV machines with 12 slots are considered, in which the number of slots per pole per phase (SPP) is 1/2, 2/5 and 2/7. Each SPP relates to two winding configurations, namely double-layer and single-layer. Based on the same electric loading, they are designed to have the same peripheral dimensions. The star of slots is applied to analyze these FSCW PMV machines initially including winding connection, winding factors. A simple method to analyze the order of the largest harmonic of PMV machines with SPP <; 1/2 induced by armature windings is proposed. By using the time-stepping finite-element method (TS-FEM), the performances of the proposed FSCW PMV machines are analyzed and compared quantitatively.