Analytical design method of stator-coreless axial flux permanent magnet machines

The most accurate method to design the stator coreless axial flux permanent magnet machine is the 3D finite-element analysis, which is exceedingly time-consuming. To solve this problem, this paper presents an analytical design method. Firstly, the analytical model of the 3D no-load magnetic field distribution of the machine is proposed. Analytical expressions of the back electromotive force of the machine are derived based on the model by using the winding function method. Inductance and resistance are calculated based on parameters such as the estimated ending connection length. Machine losses are analyzed in detail and analytical equations of them are presented. Then equations for the steady state performance are derived bases on the equivalent circuit of the machine. Finally the proposed design method is applied to three prototype machines with different rate powers and winding configurations. The prototype machines were tested and the calculated results are compared with the experimental ones, showing good agreements.