Influence of slot-pole configuration on reluctance torque in fractional-slot concentrated-winding interior permanent-magnet machines

Abstract

Due to their advantages of high efficiency, high power density, short end turns and high slot fill factor, the fractional-slot concentrated-winding interior permanent-magnet (FSCW-IPM) machines have been gaining interest over the last few years. This paper investigates the reluctance torque of FSCW-IPM machines with different slot-pole (S/P) configurations. Firstly, the calculations of the inductances of $d$ -axis and $q$ -axis are analyzed and derived, showing that the reluctance torque of the FSCW-IPM machines is closely related to the S/P configuration. Then, the reluctance torque of eight FSCW-IPM machines is comparatively investigated by using the finite-element analysis. For a fair comparison, these machines are designed based on the same size. Their electromagnetic performances, such as speed range, field-weakening capacity, are analyzed and compared. Finally, the results reveal that low pole-number and high slot-number FSCW-IPM machines have the potential to offer high reluctance torque and good field-weakening capacity.