With the rapid proliferation of industrial robots, compact electric motors have become increasingly critical for robot joint actuation. This paper proposes a fan–trapezoidal combined magnetic pole and auxiliary pole structure. A three-dimensional simulation model of a disk-type motor incorporating this magnetic pole configuration is established using the finite element analysis method. Its electromagnetic characteristics are then investigated through finite-element simulations and optimization analysis. With the total harmonic distortion (THD) of the air-gap flux density as the primary optimization objective, the optimal design is selected by adjusting the fan–trapezoidal pole angle and the dimensions of the soft magnetic auxiliary poles. The accuracy of parametric optimization is subsequently verified by employing the multi-objective genetic algorithm (MOGA). The results indicate that for a coreless axial-flux permanent magnet motor equipped with the proposed fan–trapezoidal combined poles and auxiliary poles, the THD of the air-gap flux density is reduced to 3.53%. This represents a reduction of 38.72% compared to an optimized conventional modular-pole structure. Furthermore, the harmonic distortion rate of the no-load back electromotive force decreased by 83.91%. The sinusoidal characteristics of the air-gap flux density waveform are significantly improved. This work provides insights into the design of coreless axial-flux permanent magnet motors.
Wang et al. (Sat,) studied this question.