Investigation and Comparison of Different Calculation Methods for AC Copper Loss of Flat Copper Wire in Axial Flux Permanent Magnet Motor

The AC copper loss of flat copper wire in axial flux permanent magnet (AFPM) motor can seriously affect the performance, so it cannot be ignored when optimizing the motor design. Accurate results can be obtained using 3-D transient field finite element (FE) to calculate AC copper loss. However, the calculation time is long, which is not conducive to the motor optimization design. In order to consider the effects of the external magnetic field, conductor arrangement mode, stator tooth-tip, skin effect, and proximity effect on AC copper loss and to balance the calculation accuracy and calculation time, the analytical calculation method and hybrid analytical calculation method are proposed. The analytical calculation method combines complex eddy current equation with the precise subdomain method, and the hybrid analytical calculation method combines three-dimensional FE with the analytical method. In order to comprehensively compare different calculation methods, the proposed methods are used to analyze the AC copper loss and motor efficiency under different conductor arrangement modes and working conditions, and the simulation verification is carried out by three-dimensional transient field. Finally, through the AC resistance experiment and prototype experiment, the accuracy of the proposed methods is verified, and the characteristics of different methods are summarized.