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

Joss, Andreas (2018-12)

Thesis (MEng)--Stellenbosch University, 2018.

Thesis

ENGLISH ABSTRACT: This thesis is a comparative study of the electromagnetic aspects, between the Ironless Double-rotor Radial Flux Permanent Magnet (IDRFPM) machine and the Single Outrunner Rotor Synchronous Permanent Magnet (SORSPM) machine for the application of the Mellowcabs L2 class direct-drive electrical vehicle. The IDRFPM machine is analysed analytically using the subdomain analysis method, and validated using a Finite Element Method (FEM) package. Two conductor types are considered for the SORSPM machine, namely Litz wire and solid copper bars. The SORSPM machine is subsequently analysed using a FEM package. The IDRFPM and SORSPM machines are both optimised for various pole numbers with priority given to efficiency, torque density and torque ripple. The optimisation results conclude that the IDRFPM machine has superior performance with regards to efficiency, power factor and torque ripple. However, the torque density of the 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 machine to provide sufficient hill-climbing capability. A first attempt into a possible method of constructing the 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.

AFRIKAANSE OPSOMMING: Hierdie tesis is ’n vergelykende studie in terme van die elektromagnetiese aspekte, tussen die Ysterlose Dubbel-rotor Radiale Vloed Permanente Magneet (YDRVPM) masjien en die Enkel Buite-rotor Sinkroon Permanente Magneet (EBSPM) masjien, vir die toepassing van die Mellowcabs L2-klas direk-aangedrewe elektriese voertuig. Die YDRVPM masjien is analities geanaliseer met behulp van die subdomein analitiese metode en die resultate daarvan is bevestig met ’n Eindige-Element Metode (EEM) sagteware program. Vir die EBSPM masjien, word twee geleier tipes oorweeg, naamlik Litz draad en soliede koperstawe. Die EBSPM masjien is gevolglik met behulp van EEM sagteware geanaliseer. Beide die YDRVPM en EBSPM masjiene is vir verskeie poolnommers geoptimeer, terwyl uitkomstes soos die benuttingsgraad, draaimomentdigtheid en rimpel draaimoment geprioritiseer was. Dit was egter gevind dat die draaimomentdigtheid van die YDRVPM masjien (2.70 N m/kg) heelwat laer is as dié van die EBSPM masjien (7.17 N m/kg). Die YDRVPM masjien se teleurstellende draaimomentdigtheid maak die masjien ’n onpraktiese keuse vir die toepassing, omdat dit die voertuig se gewig aansienlik sal vergroot, wat op keer selfs ’n groter YDRVPM masjien sal verg om die nodige draaimoment vir opdraendes te voorsien. ’n Eerste poging, aangaande ’n moontlike metode vir die konstruksie van die EBSPM masjien wat soliede koperstawe benut, wys dat die masjien te ingewikkeld sal wees om te bou. Die soliede koperstaaf opsie se ingewikkelde konstruksie, tesame met die onoortuigende prestasievermoë, het tot gevolg dat, die EBSPM masjien wat Litz draad gebruik, die aanbevole masjien vir die Mellowcabs toepassing is.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/104977
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