Iron Losses Calculation of an Axial Flux Machine Based on Three-Dimensional FEA Results Corresponding to One-Sixth Electrical Period

Abstract

This paper describes the iron losses calculation of an axial flux machine with yokeless and segmented armature structure based on the limited three-dimensional (3-D) finite element analysis (FEA) results corresponding to one-sixth electrical period. Considering, the 3-D magnetic flux in both stator segments and rotor yoke, soft magnetic composites are used to manufacture the soft magnetic components. Furthermore, time-consuming 3-D FEA is necessary to evaluate the performance of the machine accurately. Due to the magnetic periodicity, most of the characteristics of the machine can be easily determined through averaging the limited 3-D FEA results. However, in some models the calculation of iron losses requires always the flux density waveform in each soft magnetic composites (SMC) element of the FEA model for an entire electrical period, especially when the losses resulted by minor loops should also be taken into account. Therefore, a general method to reconstruct the complete flux density waveform in each SMC component of the FEA model based on limited 3-D FEA results is suggested in this paper. Subsequently, the iron losses can be calculated with various models in time or frequency domain. Finally, the suggested method is validated by comprising the measurement of a prototype with the calculated iron losses based on the classical Bertotti formula.