Analytic calculation of axial-flux permanent-magnet motor torque

It is proved that fast semi-analytic methods can be applied to perform the threedimensional design calculation of axial-flux permanent magnet machines successfully. The analytic calculation can be summarised in the following three steps: first, each axial-flux permanent-magnet machine pole pair – or several pole pairs in the case of fractional slot windings – is divided on the airgap surface radially into sectors-of-rings, which then form the airgap surfaces of elementary machines. Secondly, the behaviour of each elementary machine is calculated individually assuming a two-dimensional flux problem. Thirdly, the machine properties are found by summing the results given by all the elementary machines and all pole pairs of the machine.