Optimization of Axial-Flux PM Machines for Improved Torque Density by Simple Non-Linear Magnetic Analysis

In this paper, a simple non-linear magnetic analysis- based optimum design of axial-flux permanent magnet (AFPM) machines is presented, which realizes the maximization of torque density while keeping motor volume. The proposed analysis consists of the geometric-flux-tube-based equivalent-magnetic-circuit model. The model includes saturable permeances taking into account the local magnetic saturation in the core. At first, the validity of the proposed analysis is examined for the various design free parameters. After verifying the accuracy of the torque computation of the proposed analysis through the comparisons with 3D-FEA, 8-pole 12-slot AFPM machine is optimally designed. Comparing to the traditional 3D-FEA, the design method proposed here has the same accuracy, while the computation time is as short as 1/700.