Design to Reduce Modulated Vibration in Fractional-Slot Concentrated-Windings PM Machines Considering Slot–Pole Combination

The superior torque performance and unsatisfactory vibration are the inherent contradiction issue in fractional-slot concentrated-windings (FSCW) permanent magnet (PM) machines. This article aims to reduce the modulated vibration in FSCW PM machines while preserving their great torque performance. First, the contradictory relationship between the torque performance and the vibration of FSCW PM machines is revealed from the perspective of the slot–pole combination. Then, the radial force modulation of the FSCW PM machine is investigated from the aspects of spatial order and magnitude modulation. Subsequently, a new vibration reduction design methodology is presented, which combines the optimal slot opening coefficient and modified slot–pole combination. Finally, the prototype of a 12-slot/14-pole FSCW PM machine is manufactured, and several simulated and experimental verifications are carried out to validate the theoretical analysis.