Efficient Calculation and Mitigation of AC Winding Losses in Axial Flux Permanent Magnet Machine

This article introduces mitigation approaches for reducing alternating current (AC) winding losses in an axial flux permanent magnet (AFPM) machine using a computationally efficient loss estimation model. In this paper, a complete three-dimensional (3-D) finite element analysis (FEA) model, a hybrid model, and a new proposed method based on homogenized technique are compared to calculate AC winding loss in a Yokeless and Segmented Armature (YASA) AFPM machine in terms of accuracy and calculation time. The proposed method can decrease simulation time by 97.6%, while maintaining accuracy with 3.9% error at high speeds of machine (AC winding loss) compared to detailed 3-D FEA that models each individual turn. In the second half, the proposed calculation methodology is applied to mitigate AC winding losses by separating the coils from the air gap (considering trade-offs such as increased axial length, iron loss, and torque degradation), reducing wire height (compensating for this with increased direct current (DC) winding loss), and segmenting wires by leveraging the symmetry of the YASA type AFPM machine. Finally, each approach is combined to mitigate AC winding losses while minimizing the trade-off and compared with the initial model in terms of loss distributions and efficiency.