Design of an ironless doublee-rotor radial flux air-cored permanent magnet machine

Oosthuizen, Gert Immelman (2016-03)

Thesis (MEng)--Stellenbosch University, 2016.

Thesis

AFRIKAANSE OPSOMMING: Hierdie tesis bevat navorsing oor die Ysterlose Dubbel-rotor Radiale Vloed Permanente Magneet (YDRVPM) masjien. Die masjien word uitgeken deur 'n rotor topologie wat slegs magnete bevat en sonder 'n yster juk, met die doel om gewig te verminder en algemene wringkragdigtheid te verbeter. Tangent gemagnetiseerde tussenpoolmagnete sluit die vloedpad wat normaalweg deur die yster juk gedoen sou word. Die ontwerp bevat ook lugkern gekonsen- treerde windings wat kernverliese en rat elimineer en terselfdetyd koperverliese verminder. Die navorsing is voorafgegaan deur aanvanklike werk wat 'n rof maar funk-sionele aluminium prototipe ogelewer het. 'n Prim^ere fokus is om te verbeter op hierdie aanvanklike topologie en om 'n nuwe prototipe te bou met verbeterde wringkragdigtheid. Die nuwe prototipe sal dien as 'n dryfmotor vir 'n Shell Eco Marathon (SEM) voertuig, aangesien die lae gewig eienskappe van die masjien ideaal geskik is vir 'n ligte voertuig toepassing. Die YDRVPM ontwerp is egter 'n verwerking van yster-juk masjiene wat gebruik is in windkragopwekking toepassings. As sulks mik hierdie navorsing om insig te verkry wat later op wind tegnologie toegepas kan word, naamlik toepassings van vertikale as wind turbines (VAWTs). Elektromagnetiese, struktuur en termiese analsise is voltooi as deel van 'n multi-fisika ontwerpsbenadering. Die elektromagnetiese ontwerp het aangedui dat 'n inlyn gesegmenteerde kwasi-Halbach magneet opstelling met pool en tussenpool magnete van ekwivalente wydte die meeste wringkrag lewer. Koolvesel versterkte plastiek is gebruik vir strukturele komponente om wringkragdigtheid te verbeter. Gedetaillerde meganiese ontwerp is voltooi en strukturele integritiet is nagesien met gebruik van ANSYS Mechanicalr sagteware. Die maksimum veilige werkspunt is evalueer deur termiese analise. 'n Basiese temiese model van die masjien is verkry deur die masjien as 'n ingewikkelde netwerk van termiese weerstande te beskou. Vervaardiging van 'n prototipe geskik om te dien as dryfmotor vir 'n SEM voertuig was suksesvol sowel as toetse op die masjien. Terwyl benuttingsgraad effens laer as berekende waardes was het die masjien goeie wrinkragdigtheid behaal. Die prototipe bevat 'n lae persentasie strukturele massa maar bied tog die nodige raam waarop 'n 20"fietsband direk geplaas kan word.

ENGLISH ABSTRACT: This thesis presents research on the Ironless Double-rotor Radial Flux Perma- nent Magnet (IDRFPM) machine. The machine is characterised by a rotor topology consisting of magnets with no iron yoke, which aims to reduce weight and improve overall torque density. Tangentially magnetized inter-pole magnets complete the flux path as would normally be done by the steel yoke. The design also features air-cored concentrated windings which eliminate core losses and cogging torque while reducing copper losses. The research was preceded by initial work which produced a crude but functional aluminium prototype. A primary focus is to improve the topology used in the first prototype and construct a new prototype with improved torque density. The new prototype will serve as a propulsion motor for a Shell Eco Marathon (SEM) vehicle, since the lightweight characteristic suits a small vehicle application. However, the IDRFPM design is derived from steel-yoke machines used in wind power generation applications. As such, this research aims to gain insights to later be applied to wind technology, particularly for applications in vertical axis wind turbines (VAWTs). Electromagnetic, structural and thermal analysis was performed as part of a multi-physics design approach. The electromagnetic design concluded that best performance is achieved with an in-line segmented quasi-Halbach magnet array with pole and inter-pole magnets of equal width. To maximize torque density, advanced carbon fibre reinforced plastic (CFRP) was selected to comprise the frame components. Detailed mechanical design was completed and ANSYS Mechanicalr software was used to assess structural integrity. Ther- mal analysis was performed to verify the maximum safe operating point. A basic theoretical model was created by approximating the machine as an intricate thermal resistance network. A prototype fit to function as a SEM vehicle propulsion motor was successfully manufactured and tested. While efficiency was slightly lower than anticipated, the machine achieved good torque density. The prototype contains a low percentage structural mass while providing a frame on which a 20" bicycle tire can be directly mounted.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/98511
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