This thesis describes research contributions in the field of electrical machines for operation at elevated temperatures. High temperature operation of electrical machines is considered critical for the realisation of the 'more-electric aircraft' concept, which involves electrical machines embedded directly on to the shafts of the aircraft gas turbine. The particular machine of interest for this thesis is a switched reluctance machine for operation on the high pressure shaft. The hostile environment, mainly due to the high temperatures (~350°C ambient) introduces several challenges in the modelling, design and manufacture of electrical machines. In order to aid selection of materials and collect necessary data for the machine design, detailed analysis of the published magnetic and electrical data for key materials at high temperatures has been carried out. Further measurements on the high strength 50% Cobalt Iron materials were also conducted, which supplement the understanding of the materials behaviour at high temperatures, specifically in terms of the effects of the long term thermal ageing on the individual loss mechanisms in the material. The design optimisation of an SR machine for 350°C operation is also described in detail. The design procedure illustrates how the high temperature material properties influence machine performance and achievable power densities. In order to more reliably predict the performance of machines at elevated temperatures several modelling techniques have been developed. A method to calculate instantaneous core loss was introduced, which was formulated such that it could be used in circuit simulations to ensure power balance. Extensive validation of this model has also been carried out.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:577457 |
| Date | January 2013 |
| Creators | Rodrigues, Leon |
| Contributors | Geraint, Jewell |
| Publisher | University of Sheffield |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.whiterose.ac.uk/4392/ |
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