Victoria University

Current-pumping performance of axial-symmetric superconducting dynamo designs

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dc.contributor.advisor Bumby, Chris en_NZ
dc.contributor.advisor Badcock, Rod en_NZ
dc.contributor.author Phang, Sin Hoi en_NZ
dc.date.accessioned 2017-07-20T01:18:01Z
dc.date.accessioned 2020-08-10T23:22:03Z
dc.date.available 2017-07-20T01:18:01Z
dc.date.available 2020-08-10T23:22:03Z
dc.date.copyright 2017
dc.date.issued 2017
dc.identifier.uri http://restrictedarchive.vuw.ac.nz/handle/123456789/9313
dc.identifier.uri http://researcharchive.vuw.ac.nz/handle/10063/9096
dc.description.abstract In this project, the current pumping performances of three high temperature superconducting (HTS) dynamos (mechanically-rotating flux pumps) were investigated. These flux pumps (FPs) were identified as the Gen 1, Gen 2 and Gen 4 FP respectively. They were modelled using simple DC equivalent circuits and their performances were defined by three output parameters: DC open-circuit voltage (Voc), dynamic resistance (Rd) and DC short-circuit current (Isc). The experimental results showed that these FPs produced non-zero DC output voltages across their stators and each supplied DC output currents into series connected superconducting circuits. The Gen 1 FP was cooled with liquid nitrogen and operated at 77 K. The stators were made from 12-mm wide copper-coated yttrium barium copper oxide (YBCO) HTS conductors. The objective of the experiment was to investigate the effect of the rotor magnet size, geometry and orientation (with respect to the stators) on the FP performance. The design parameters, based on the width and the length of the magnet with respect to the stator, for optimal FP performance were determined. The Gen 2 FP was also cooled with liquid nitrogen and operated at 77 K. The stators were made from 46-mm wide Ag-coated YBCO HTS conductors. The objective of the experiment was to investigate the effect of stator width on the FP performance at various magnet frequencies. This was done by slitting two of the stators to form parallel stators with equal width, but smaller than the original conductor width. The experimental results showed that the FP performance was highly dependent on the operating frequency. Three operating frequency regimes were observed: low, mid and high. At high frequency, the Voc decreased and the Rd increased signifcantly. This was attributed to the local heating effect in the stator due to the increase in the current density. As a result, the FP produced zero output current in this regime. The AC voltage waveforms measured across the stators in different frequency regimes were very different in shapes and amplitudes. Therefore, these waveforms can be used to identify the operating frequency regime of the FP. At some operating frequencies in the mid frequency regime, bi-stable operating modes were observed, each mode resulted in different output parameters. The Gen 4 FP was constructed in this project. It was cooled via thermal conduction method using a cryorefrigerator system. It had an axial-symmetric stator design where the shape of the stator is cylindrical. The width of the stator was considerably larger compared with the Gen 1 and Gen 2 FPs. The experiment objective was to investigate whether this design would produce a DC current, and then characterise the FP performance at different operating temperatures. The experimental results showed that the time-averaged DC output voltage of the Gen 4 FP was much higher compared with the Gen 1 and Gen 2 FPs. The reason is that it produced a DC output voltage for almost the entire rotor cycle. The experimental results also indicated that the Gen 4 FP has the capability to produce output currents in the kA range. en_NZ
dc.language.iso en_NZ
dc.publisher Victoria University of Wellington en_NZ
dc.subject HTS flux pumps en_NZ
dc.subject High temperature superconducting flux pumps en_NZ
dc.subject Superconducting dynamos en_NZ
dc.subject Drum flux pumps en_NZ
dc.subject HTS magnets en_NZ
dc.subject High temperature superconducting magnets en_NZ
dc.subject Second generation HTS superconductor en_NZ
dc.subject Second generation high temperature superconducting superconductor en_NZ
dc.title Current-pumping performance of axial-symmetric superconducting dynamo designs en_NZ
dc.type Text en_NZ
vuwschema.contributor.unit School of Chemical and Physical Sciences en_NZ
vuwschema.type.vuw Awarded Research Masters Thesis en_NZ
thesis.degree.discipline Physics en_NZ
thesis.degree.grantor Victoria University of Wellington en_NZ
thesis.degree.level Master's en_NZ
thesis.degree.name Master of Science en_NZ
vuwschema.subject.anzsrcfor 020404 Electronic and Magnetic Properties of Condensed Matter; Superconductivity en_NZ
vuwschema.subject.anzsrcseo 970102 Expanding Knowledge in the Physical Sciences en_NZ


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