2-D analytical magnetic model for optimal design of an outer rotor permanent magnet synchronous machine

The objective of this paper is to investigate the optimal design of a 120 W outer-rotor permanent magnet synchronous machine for air-conditioning applications to reduce the electricity consumption and machine costs. To this end, a 2-D analytical magnetic model, combined with a teaching-learning based optimisation algorithm is employed. The objectives are to simultaneously maximise the machine efficiency and minimise the material cost. Constraints such as the required output torque, predefined machine volume, maximum allowable torque ripple and unbalanced magnetic force and limitations to avoid iron core magnetic saturation are imposed simultaneously. To find the flux density in iron parts, a new method based on the subdomain technique has been presented. To evaluate the analytical model in terms of accuracy and speed, the results of the 2-D analytical approach are compared with those of the 2-D and 3-D linear/non-linear finite element method. Finally, a prototype of the optimised machine is fabricated and the superiority of the presented approach is demonstrated.