Magnetic field analysis and rotor optimization for coreless axial flux permanent magnet synchronous machine

The coreless axial flux permanent magnet synchronous machine (CAFPMSM) has the advantages of simple structure, low starting torque and high power density. However, the air gap magnetic field of CAFPMSM exhibits typical three-dimensional characteristics, and its effect on eddy current losses of coreless winding is different from conventional machine. Based on the results of the equivalent magnetic circuit of the air gap flux field, the rotor structure of the machine was optimally designed to optimize the output voltage distortion rate and reduce the eddy current losses of the winding. Firstly, the equivalent magnetic circuit model of the new structure motor was established. The magnetic resistance and magnetic leakage coefficient of each magnetic circuit were calculated. Then, accuracy of theoretical analysis was verified by using finite element software. Finally, the experimental prototype was measured for counter-electromotive force and eddy current loss of the machine, and the experimental results show that the distortion rate of counter-electromotive force waveform, eddy current loss and temperature rise of the new structure machine are reduced. © 2024 Editorial Department of Electric Machines and Control. All rights reserved.