This paper presents an investigation into the application of fractional-slot concentrated windings to synchronous reluctance motors. The advantages and disadvantages of the synthesis of such a machine are explored with thermal aspects included, and a comparison with a similar topology, i.e., the switched reluctance motor, is also presented where appropriate. The differences in electric drive between the two reluctance motors are briefly explored. Finite element studies show that the fractional-slot concentrated wound machine can exhibit higher efficiency and torque density when compared with conventional synchronous reluctance and induction motors, and the electromagnetic model is validated through testing of a prototype machine, with thermal results also reported. Despite the many benefits, high torque ripple and low power factor reduce the topologies' desirability and are identified as an area of further research.
Spargo, C. M., Mecrow, B. C., Widmer, J., & Morton, C. (2014). Application of Fractional-Slot Concentrated Windings to Synchronous Reluctance Motors. IEEE Transactions on Industry Applications, 51(2), 1446-1455. https://doi.org/10.1109/TIA.2014.2341733