Analytical Analysis of Axial Flux Permanent Magnet Machines with Air-Gap Winding

This paper focuses on the analytical analysis and optimization of the coreless permanent magnet machines. The general formula for the winding factor of air-gap winding is proposed. Based on the proposed theory, the comparison of different winding structures is carried out. The result shows that coreless structure would significantly lower the winding factor of concentrated winding. Meanwhile the winding factor of distributed winding is almost the same in slotted and slotless structures. The axial flux structure would narrow the gap between distributed and concentrated winding, but the winding factor of coreless concentrated winding is still lower than 0.85. After that, the analytical model of the axial flux coreless machines with Halbach array PM rotor is established to achieve the optimal design. Finally, the Finite element model is applied to prove the validity and accuracy of the proposed method.