Design optimisation of a transverse flux linear oscillating generator for resonant free-piston Stirling applications

Joubert, Louis Hoogenhout (2015-03)

Thesis (MSc)--Stellenbosch University, 2015.

Thesis

ENGLISH ABSTRACT: The design optimisation of a linear oscillatory electric generator for application in freepiston Stirling engines is described in this thesis. A basic overview of free-piston Stirling engine technology is given by firstly providing a brief description of the operation of the heat engine. The applications of free-piston Stirling engines in industry are given and the proposed future applications are described. Different types of electrical machine designs from industry and academia are evaluated in a literature study. A classification structure is also proposed based on the magnetic flux variation within the designs. Based on the literature study, a transverse flux, single-phase, moving magnet, tubular topology was chosen for investigation. Athree dimensional finite element simulation was chosen as the most appropriatemethod to model the linear electrical machine. A commercial simulation package was called from a simulation script and the outputs from the finite element simulation were again used to calculate the electrical machine performance parameters using the instantaneous voltageand current values. A sequential quadratic programming algorithm was used to perform optimisation of the machine topologies, with the optimisation variables being dimensional parameters that describe the machine geometry and the goal of the optimisation to minimise the active mass of the machine, while maintaining preset minima for the output power and the efficiency. The machine was optimised for a number of different translator configurations and the different configurations were analysed and compared. It was found that a quasi-Halbach arrangement of the permanent magnets yielded the lowest overall active mass. A comparative study is also presented, where this quasi-Halbach variant is compared to a commercial machine. It was found that the linear machine design with a quasi-Halbach arrangement compares well with the commercial machine. A prototype and test bed was designed and constructed. Due to manufacuring difficulties however, the machine could not be completed in time for testing.

AFRIKAANSE OPSOMMING: Die ontwerpsoptimering van ’n lineêre ossillerende elektriese generator vir toepassing in vrysuier Stirling enjins word beskryf in hierdie tesis. ’n Basiese oorsig van vrysuier Stirling enjin tegnologie word gegee deur eerstens ’n kort beskrywing te gee van die werking van die hitte-enjin. Die aanwending van vrysuier Stirling enjins in industrie word gegee en voorgestelde toekomstige toepassings word beskryf. Verskillende tipes elektriese masjien ontwerpe vanuit die industrie en die akademie word geëvalueer in ’n literatuurstudie. ’n Klassifiseringstruktuur, gebaseer op die magnetiese vloedverandering in die ontwerpe, word ook voorgestel. ’n Transverse vloed, enkelfase, bewegende magneet, tubulêre topologie is gekies vir die ondersoek, gebaseer op die onder andere die literatuurstudie. ’n Drie-dimensionele eindige element simulasie is gekies as die mees geskikte metode om die lineêre elektriese masjien te modelleer. ’n Kommersiële simulasie pakket is deur middel van ’n simulasie skrip geroep en die uitsette vanaf die eindige element simulasie is weer gebruik om die werksverrigtingsparameters van die elektriese masjien te bereken deur gebruik te maak van die oomblikswaardes van die spanning en stroom. ’n Sekwensiële kwadratiese programmering algoritme is gebruik om optimering van die masjien topologieë te doen, met die dimensionele parameters wat die masjien geometrie beskryf as die optimeringsveranderlikes en doel van die optimering om die aktiewe massa van die masjien te minimeer, terwyl die uitsetdrywing en die benuttingsgraad by voorafgestelde minima gehou word. Die masjien is geoptimeer vir verskeie translator konfigurasies en die verskillende konfigurasies is geanaliseer en vergelyk. Dit is bevind dat ’n kwasi-Halbach skikking van die permanente magnete die laagste totale aktiewe massa gelewer het. ’n Vergelykende studie is ook aangebied, waar die kwasi-Halbach variant vergelyk is met ’n kommersiële masjien. Dit is bevind dat die lineêre masjien met die kwasi-Halbach skikking baie goed vergelyk met die kommersiële masjien. ’n Prototiepe masjien en toetsopstelling is ontwerp en aan mekaar gesit. Maar as gevolg van vervaardigbaarheids tekortkominge kon toetse op die prototiepe nie betyds gedoen word nie.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/96849
This item appears in the following collections: