Analysis and calculation for air gap leakage and open circuit air gap flux density of disc motor

To avoid the huge time consumption in the initial and optimum design of axial flux permanent magnet motor where 3D-FEM was used to calculate the flux leakage coefficient and air gap flux density, by analyzing the magnetic circuit of the disc PM motor, establishing the equivalent magnetic network model and calculating the equivalent magnetic reluctances, the analytical expression of the leakage coefficient of the machine was obtained. The end effect correction function of air gap magnetic field was obtained by dichotomy optimization which was suitable for different sizes, different pole slot composing and different structure types of axial magnetic disc permanent magnet motors. The relative air gap permeance function at 24 slots of the disc PM motor was calculated analytically. Then, the analytical model of open circuit air gap flux density was established at average radius taking the slot effect into consideration. Finally, the analytical results were compared with the results of FEM. The coincidence degree of the data is high, which proves the accuracy of the equivalent magnetic network model and the open circuit air gap flux density analytical model. © 2021, Harbin University of Science and Technology Publication. All right reserved.