Design of a single-sided axial flux PM in-wheel electric vehicle machine with non-overlap stator windings

Kierstead, Harold Junior (2009-12)

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009.

Thesis

ENGLISH ABSTRACT: With the current worldwide energy problems electric vehicles are set to replace conventional combustion engine vehicles. Electric vehicles with gearless in-wheel mounted brushless permanent magnet motors provide a more flexible and efficient means of vehicle propulsion but the electric motors, particularly the non-overlap stator winding type have not been fully researched. This study focuses on the selection and design of suitable in-wheel hub drive machine. Several machine topologies are evaluated and the single-sided axial flux machine is chosen. The average vehicle requirements are determined and design optimisations are carried with the aid of finite element analysis and an optimisation algorithm. A comparison of torque quality between single-layer and double-layer machines is carried out and it is found that double-layer machines have the least torque ripple and single-layer machines with un-equal teeth the best torque per ripple characteristics. A 16 kW, 30-pole 27-slot prototype machine optimised for power density is built, and it is found fitting for the application meeting the design requirements. The prototype machine is extensively tested and good agreement is found between finite element and measured results. The well known axial flux attraction forces are encountered in the prototype machine and they are overcome by suitable bearing selection and mechanical design. It is found that theoretical and measured cogging torques are inconsistent, the reason for this is that practical machines are not absolutely ideal due to material and manufacturing tolerances. Excessive rotor losses are found in the prototype machine and appropriate methods for their reduction are presented. This work does not aim to find the best in-wheel hub drive solution, but instead looks to uncover some of the technical available solutions.

AFRIKAANSE OPSOMMING: Met die huidige wêreldwye energie probleme, is elektriese voertuie bestem om konvensionele binnebrandenjin voertuie te vervang. Elektriese voertuie met ratlose binnewiel-geleë borsellose permanente magneet motors, voorsien „n meer aanpasbare en effektiewe metode van voertuig aandrywing, maar die elektriese motors, veral die oorvleulende stator winding tipe is nog nie ten volle nagevors nie. Hierdie studie fokus op die keuse en ontwerp van „n binnewiel aandryf masjien. Verskeie masjien uitlegte word geëvalueer en „n enkelkant aksiaalvloed masjien is gekies. Die gemiddelde voertuig behoeftes word bepaal en ontwerp optimalisering word uitgevoer met behulp van eindige element analise en „n optimaliserings algoritme. Enkellaag en dubbellaag masjiene se draaimoment kwaliteit word vergelyk. Die bevinding is dat dubbellaag masjiene die laagste draaimoment rimpel toon terwyl die enkellaag masjiene, met oneweredige tande, die beste draaimoment per rimpel karakteristieke toon. „n 16 kW, 30 pool, 27 gleuf prototipe masjien, wat vir drywingsdigtheid ge-optimaliseer is, is gebou en is geskik vir die toepassing en die vereistes. Die prototipe masjien is getoets en goeie vergelykings word getref tussen die eindige element analise en die gemete resultate. Die alom bekende aksiaal vloed aantrekkings kragte word in die prototipe masjien gesien en word oorkom deur die regte rollaer keuse en meganiese ontwerp. Nog „n bevinding is dat die teoretiese en gemete waardes vir die vertandings draaimoment nie ooreenstem nie. Die rede hiervoor is dat die praktiese masjien nie ideaal is in terme van materiaal en vervaardigings toleransies nie. Groot rotor verliese in die prototipe masjien is gevind en goeie metodes vir die minimering daarvan word voorgestel. Hierdie werk is nie „n soektog na die beste binnewiel aandrywings oplossing nie, maar mik eerder om sommige van die tegniese beskikbare oplossings te onthul.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/2007
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