| This thesis proposes a new design technique for interior permanent magnet machines (IPMM) called axial shaping, which divides the rotor unit into several segments stacked in the axial direction. Axial shaping aims to reduce the torque ripple and improve the magnet utilization in conventional IPMMs by changing the PM width, the length of the segments, and the pitch of the pole arc on the surface of each rotor segment. The Differential Evolution (DE) algorithm was used to carry out the optimization by incorporating a multi-slice method to solve a 3D finite element (FE) optimization problem. The axial shaping method was applied to the V-type, I-type, Spoke-type, and Flux-intensifying IPMM in order to investigate the conceptual feasibility in these IPMM designs. In addition, the method combines the one and a half slot per pole per phase windings to provide additional overall benefits in proposed IPMM designs. The results in all the designs using axial shaping indicate significant torque ripple reduction, when compared with the baseline 2007 Camry motor with pole shaping. A proof-of-concept prototype was designed and constructed in the thesis in order to verify the claims predicted by FE analysis. Both test results and FE results are presented. The predicted back EMF, torque capability, cogging torque, torque ripple, and efficiency have shown generally good agreement with the experimental results. Overall, the test results are solid and the demonstration validates the benefits claimed by axial shaping. |
