Design optimisation of an outer-rotor permanent magnet synchronous hub motor for a low-speed campus patrol EV

This study proposes an outer-rotor permanent magnet synchronous hub motor (PMSHM) with similar pole and slot numbers for an electric vehicle (EV). First, the design rule of the motor size is introduced. Second, the appropriate numbers of motor poles and slots are selected to improve the torque density and save the radial space of the motor. Meanwhile, the selected poles and slots numbers can ensure that the high-efficiency area of the motor meets the requirements of the test EV. Moreover, different winding arrangements are studied to select the appropriate winding arrangement method for the motor. Then, the key dimensions of the stator are optimised to improve the torque output and reduce the core loss of the motor by using the finite element analysis. The results indicate that the proposed outer-rotor PMSHM with similar pole and slot numbers and double-layer short distance concentrated slot winding exhibits high-efficiency and high-torque output. Finally, the predicted performance of the proposed PMSHM is verified by experiments on a prototype. Furthermore, the vehicle test is also carried out, and the results show that the prototype maintains high efficiency in the main working area of the EV.