Detailed analytical method for predicting the steady-state time variations and entire harmonic contents of principal performance characteristics in a non-slotted axial flux permanent magnet motor, considering a precise iron loss model

The harmonic contents of principal performance characteristics in an electrical machine are important due to several reasons, especially because they influence the machine acoustic noise generation capability. Therefore, they should be accurately calculated considering the various electromagnetic effects involved in the machine operation. Accordingly, this study proposes a detailed analytical model for predicting the time waveforms and harmonic contents of the principal performance characteristics of a double-sided TORUS-type non-slotted axial flux permanent magnet motor with surface-mounted magnets at steady state under any given loading conditions. The armature-reaction magnetic field and inductances are exactly calculated considering both the effects of coil sides and end windings as well as that of the winding distribution. Most notably, the aggregate iron loss of machine and its influence on armature currents is precisely modelled based on the magnetic field distribution in iron parts. By establishing and solving the differential equation system of motor in the two cases with or without the neutral wire, the armature currents, speed and torque ripples, input/output powers, and copper and iron losses are all achieved with the entire harmonic content and highest accuracy. The comparison of results with those of finite element analysis and real test then validates the model.