6-Slot/2-Pole Permanent Magnet Motors with Non-overlapping Two Coil-Pitch Windings for Ultra-High-Speed Applications

In this paper, a 6-slot/2-pole ultra-high-speed permanent magnet (UHSPM) motor with non-overlapping 2 coil-pitch windings is designed for industrial and domestic applications. The proposed UHSPM motor is optimized for maximum torque density considering stator thermal limitation. Its electromagnetic performance and mechanical strength are evaluated by the finite element method, together with the investigation on the influence of winding connection types and rotor eccentricities. As will be shown, the non-overlapping 2 coil-pitch windings offer advantages of short end-winding axial length, high torque density, and high rotor mechanical strength. The series winding connection is superior to the parallel connection since the unbalanced inductances and resistances of two parallel-connected coils in one phase result in circulating currents and unbalanced magnetic force. Several predicted results are validated by experiments based on a prototype motor.