Analysis and Optimization of Cogging Torque in Yokeless and Segmented Armature Axial-Flux Permanent-Magnet Machine with Soft Magnetic Composite Core.

摘要

Yokeless and segmented armature (YASA) axial-flux permanent-magnet machine has high power density and efficiency, which is suitable for in-wheel or near-wheel direct-drive electric vehicles. This paper investigates the cogging torque of a YASA with soft magnetic composite (SMC) core. Firstly, the structure of SMC-based YASA is introduced. Then, the influence of magnet pole-arc ratio, magnet skewing, stator shoe width ratio and stator shoe shifting on cogging torque is analyzed. Based on which, the cogging torque is optimized by response surface model and genetic algorithm (GA). Finally, the optimization results are verified by 3-D finite-element method (FEM). The results confirm that, based on a certain magnet pole-arc ratio, there exists an optimum combination of magnet skewing angle, stator shoe width ratio and stator shoe shifting angle for the cogging torque minimization, while the main performances of the machine remain nearly invariable.