Dual Airgap Stator- and Rotor-Permanent Magnet Machines With Spoke-Type Configurations Using Phase-Group Concentrated Coil Windings

This paper presents an advanced design procedure for stator-based and rotor-based permanent magnet (PM) machines to improve the electromagnetic performance by incorporating the spoke-type magnet configurations, phase-group concentrated coil windings, and an unaligned arrangement of two rotors/stators. The dual-rotor switched flux PM machine (SFPMM), designated as the stator-PM machine, and the dual-stator spoke-type interior PM machine (S-IPMM), termed the rotor-PM machine, are designed by the proposed design procedure to obtain high torque density and low pulsating torques for direct-drive applications. A quantitative comparison is performed between the proposed SFPMM and S-IPMM, and a conventional SFPMM with concentrated windings is adopted as the referenced model to evaluate the contribution of the proposed design procedure. The machine performance including back electromotive force, cogging torque, and electromagnetic torque is first analyzed by a finite element method under the same operating conditions. Finally, a prototype of the dual-stator S-IPMM is manufactured, and some key simulation results are verified by the experimental tests.