Design and Optimisation of a Hub Drive Electrical Motor for an L2 Class Electrical Vehicle for Sustainable Urban Transport Applications

[摘要] ENGLISH ABSTRACT: This thesis is a comparative study of the electromagnetic aspects, between the IronlessDouble-rotor Radial Flux Permanent Magnet (IDRFPM) machine and the Single OutrunnerRotor Synchronous Permanent Magnet (SORSPM) machine for the application ofthe Mellowcabs L2 class direct-drive electrical vehicle. The IDRFPM machine is analysedanalytically using the subdomain analysis method, and validated using a Finite ElementMethod (FEM) package. Two conductor types are considered for the SORSPM machine,namely Litz wire and solid copper bars. The SORSPM machine is subsequently analysedusing a FEM package. The IDRFPM and SORSPM machines are both optimised forvarious pole numbers with priority given to efficiency, torque density and torque ripple.The optimisation results conclude that the IDRFPM machine has superior performancewith regards to efficiency, power factor and torque ripple. However, the torque density ofthe IDRFPM machine (2.70 N_m/kg) is much lower than that of the SORSPM machine(7.17 N_m/kg). The IDRFPM machine's low torque density makes it an infeasible choice,as it would increase the vehicle mass significantly, requiring yet a larger IDRFPM machineto provide sufficient hill-climbing capability. A first attempt into a possible method of constructingthe SORSPM machine using solid copper bars reveals that the complexity would be too high. The construction complexity, together with unconvincing performance gains of the solid copper bar type, makes the SORSPM machine using Litz wire the preferred candidate for the Mellowcabs vehicle.

[发布机构] Stellenbosch University