Design and Analysis of a Rotor-Coreless Multi-Disk Axial Flux Permanent Magnet Motor with Unaligned Permanent Magnets

In this paper, a novel rotor-coreless multi-disk axial flux permanent magnet motor (RCMD-AFPMM) with unaligned permanent magnets (PMs) and the skewed stator structure is proposed. The upper and lower surfaces of the sector-shaped PMs in the proposed RCMD-AFPMM are circumferentially offset by a specific angle. The unaligned PMs, combined with a skewed stator structure, superimpose the peaks and valleys of the cogging torques and torques from the two rotors, thereby suppressing cogging torque and torque ripple. Firstly, the topology of the proposed RCMD-AFPMM and conventional multi-disk AFPMM is introduced. Secondly, the key parameters such as stator slot width, skewed angle between two stators upper and lower rotor, unaligned angle of PM, and so on are analyzed. Finally, the performance of the proposed RCMD-AFPMM and conventional multi-disk AFPMM is compared by the finite element method. Consequently, the proposed RCMD-AFPMM has led to a substantial reduction of 88.78% in cogging torque and 71.31% in torque ripple, significantly enhancing performance.