Axial Flux Permanent Magnet Electrical Machine with High Torque Density: Research on the Influence of Combined-Halbach Array on YASA Machine

To increase power and torque density, a combined-Halbach array for the axial flux permanent magnet machines (AFPMMs) with yokeless and segmented armature (YASA) is presented in this paper. Firstly, the YASA machine models with conventional axial magnetized magnets and combined-Halbach array magnetized magnets are established using 3-D finite-element method (FEM). Then, the torque, torque per magnet-volume and no-load back-EMF are calculated, and the performance of two machines are analyzed and compared. It is demonstrated that the combined-Halbach array can improve the torque density of the machine and the utilization rate of the magnets. On this basis, the combined-Halbach array rotor is optimized, where the unequal thickness magnets rotor is established, and its torque density is calculated under different thickness. The results show that the combined-Halbach array with unequal thickness magnets can reduce the amount of permanent magnet materials, thus improving the utilization of magnets and reducing the costs.