Evaluation and design aspects of magnetic gears and magnetically geared electrical machines

Gerber, Stiaan (2015-12)

Thesis (PhD)--Stellenbosch University, 2015.

Thesis

ENGLISH ABSTRACT: In the past decade, magnetic gears and magnetically geared electrical machines have emerged as electromechanical devices with exceptionally high torque densities. Their distinct advantages such as low maintenance requirements and overload protection make these devices attractive for many applications. Although significant amount of research has been carried out in this fast-moving field, there are still many design related aspects that have not been thoroughly investigated. This study is concerned with the design optimization and performance evaluation of these devices. An efficient design optimization methodology, specifically aimed at magnetically geared machines (MGMs), is proposed. This design approach allows the components of these integrated machines to be appropriately matched. Challenges associated with the accurate modeling of these special machines, such as the prediction of the impact of end-effects and the high computational cost of simulating movement, are investigated. The proposed design methodology is successfully applied to the design of two different MGMs, of which one features a novel rotor structure. Prototypes based on the designs have been constructed and experimentally evaluated. There is generally a good correlation between the predicted and measured performance results. A method of analyzing the operating points of these machines is also presented. In addition to the two MGMs, a vernier machine, which is based on similar operating principles, is designed, constructed and experimentally evaluated. A detailed comparison of these machines with a more conventional direct-drive permanent magnet machine is conducted in order to assess their respective advantages and disadvantages. The comparison considers small machines with an active stack length of 50mm and an outer diameter of 140 mm. In this fixed-volume comparison, it is found that the MGMs are superior in terms of their torque capability and efficiency. The vernier machine also has a good efficiency and produces the highest torque per volume of magnet material. Based on the merits of MGMs that are demonstrated in this study, further development of these machines is warranted.

AFRIKAANSE OPSOMMING: In die afgelope dekade het magnetiese ratte en magneties-geratte elektriese masjiene na vore gekom as toestelle met besondere hoë draaimomentdigthede. Hul merkbare voordele soos lae onderhoudsvereistes en oorbelastingbeskerming maak hierdie toestelle aantreklik vir baie toepassings. Alhoewel ’n beduidende hoeveelheid navorsing reeds in hierdie vinnig-bewegende veld gedoen is, is daar steeds verskeie ontwerpsaspekte wat nie behoorlik ondersoek is nie. Hierdie studie is gemoeid met die ontwerp optimering en werkverrigting evaluasie van hierdie toestelle. ’n Doeltreffende ontwerp optimeringsmetodiek wat spesifiek op magneties-geratte masjiene (MGMe) gemik is, word voorgestel. Dié ontwerpsbenadering maak dit moontlik om te verseker dat die komponente van hierdie geïntegreerde masjiene onderling geskik is. Uitdagings wat met die akkurate modellering van hierdie spesiale masjiene geassosieer word, soos die voorspelling van die impak van eindeffekte en die hoë berekeningskoste van simulasies met beweging, word ondersoek. Die voorgestelde ontwerpsmetodiek word suksesvol toegepas in die ontwerp van twee verskillende MGMe, waarvan een ’n nuwe rotorstruktuur het. Prototipes gebaseer op hierdie ontwerpe is vervaardig en eksperimenteel geëvalueer. In die algemeen is daar ’n goeie korrelasie tussen die voorspelde en gemete werkverrigtingsresultate. ’n Metode waarmee die bedryfspunte van hierdie masjiene geanaliseer kan word, word ook voorgelê. Bykomend tot die twee MGMe is ’n vernier masjien, wat se werking op soortgelyke beginsels berus, ontwerp, vervaardig en eksperimenteel geëvalueer. ’n Gedetailleerde vergelyking van hierdie masjiene met ’n meer konvensionele permanente magneet masjien is uitgevoer om hul onderskeie voor- en nadele te evalueer. Die vergelyking beskou klein masjiene met ’n aktiewe stapel lengte van 50mm and ’n buite diameter van 140mm. In hierdie vaste-volume vergelyking word bevind dat die MGMe uitstyg in terme van hul draaimoment vermoë en benuttingsgraad. Die vernier masjien het ook ’n goeie benuttingsgraad en lewer die hoogste draaimoment per volume van magneet materiaal. Verdere ontwikkeling van MGMe kan geregverdig word gebaseer op die meriete van hierdie masjiene wat in hierdie studie gedemonstreer is.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/97872
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