Approach for analytical modelling of axial-flux PM machines

In the presented paper, an analytical model is developed for calculation of the air gap magnetic flux density in the axial-flux surface-mounted PM machines. The slotting effect is taken into account in the air gap magnetic flux distribution, accurately. The main novelty of this study is replacing the stator teeth by some surface currents at the border of the removed stator teeth. The uniqueness theorem is applied to find the surface currents. The two-dimensional (2D) field solution in the slotless machine is solved easily by separation of variables method. The multi-slice quasi-3D method is applied for taking 3D nature of field distribution into account. In addition, the back-EMF, armature inductances and electromagnetic and cogging torque are computed based on the predicted air gap flux density. Moreover, for the first time, the Lorentz equation besides Maxwell' stress tensor is applied for computation of the cogging torque. The validity of the proposed procedure and the obtained results are verified by 3D finite element analysis.