High Efficiency Axial Flux Permanent Magnet Machine Design for Electric Vehicles

Design and optimization of electrical machines for electric vehicle (EV) applications is a challenging task. In response to variable driving circumstances, the machine should be designed to operate in a wide range of speed and torque. This paper aims to optimize a surface-mounted axial-flux permanent-magnet (AFPM) traction machine taking the influence of the driving cycle into account. The AFPM motor is designed to maximize the overall efficiency over a predefined driving cycle. EV requirements and geometric constraints are taken into account in the design process. Hundreds of operating points in a driving cycle are reduced to the limited number of representative points by calculating the energy centre points in the energy distribution curve. Therefore, the number of calculations during the design optimization is significantly reduced. An analytical design procedure based on quasi-3D approach is used for accurate modelling of AFPM machine and genetic algorithm (GA) is implemented to find out the optimal design parameters. Functionality of the proposed approach is validated via comprehensive three-dimensional (3D) finite-element analysis (FEA).