On load analytical modelling of the magnetic field for axial flux surface-inset permanent magnet machines with semi-closed slots

This paper presents an analytical model for the prediction of the on-load magnetic field in axial flux semi-closed slots and surface-inset permanent magnets machines. The technique is based on 2-D exact solution of the Maxwell's equations in low permeability regions (slots, slot opening, airgap, permanent magnets adjacent to the airgap and moving armature slots) using the separation of variables method. The magnetic field expressions are developed in each region leading to an exact calculation of the slot effects on the airgap magnetic quantities. Finally, comparison of results issued from both the proposed model and finite element analysis (FEA) validate the efficiency and accuracy of proposed approach.