Multi-objective optimal design of an axial-flux permanent-magnet wheel motor for electric scooters

This study proposes a systematic process of a multi-objective optimal design of an axial-flux permanent-magnet motor for electric scooters. The preliminary design uses a zero-dimensional (0D) model to determine the number of slots and poles and initial sizes of the motor according to the driving requirements of the scooter. The optimal design process uses a 1D magnetic circuit model with an effective air-gap distribution function, whereas searching for a set of motor parameters that minimise or maximise motor performance indices such as torque, torque density and torque ripple. The final design is verified and refined by the 3D finite element method. The resulting prototype motor features high torque density of 8.94 Nm/kg and electronic gearshifts between low and high gears. According to their efficiency maps, the driving-cycle efficiency is estimated as 57% for the electric scooter to operate on the driving cycle ECE-40.