Three-phase motor with superconductive bearings

Buchhold, T.A.

doi:10.1016/0011-2275(65)90061-5

Cited by 8 publications

(3 citation statements)

References 2 publications

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“…Below the resonance (f < 3 Hz), the levitated structure rotates about the centre of magnetism of the bearing, and the losses are caused by the inhomogeneity of the PM's field. The resonance region (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) shown in figure 10 is relatively broad and probably includes some coupling to the vertical vibration mode. The large COF value is mainly caused by the large-amplitude radial oscillations in this frequency range.…”

Section: Bearing Dynamicsmentioning

confidence: 99%

“…While the first stable levitation that involved a superconductor was reported in 1945 [1,2], it was not until 1953 that efforts to investigate the use of superconductors in bearings and attempts to measure rotational drag were reported [3]. The first experimental motor that employed superconducting bearings was demonstrated in 1958 [4][5][6]. Despite these and other [7][8][9] pioneering efforts with low-temperature superconductors (LTSs) that were cooled with liquid helium, significant interest in superconducting bearings did not emerge until the discovery of the first HTS [10].…”

Section: Introductionmentioning

confidence: 99%

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Superconducting bearings

Hull

2000

Supercond. Sci. Technol.

466

203

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The physics and technology of superconducting bearings is reviewed. Particular attention is given to the use of high-temperature superconductors (HTSs) in rotating bearings. The basic phenomenology of levitational forces is presented, followed by a brief discussion of the theoretical models that can be used for conceptual understanding and calculations. The merits of various HTS bearing designs are presented, and the behaviour of HTS bearings in typical situations is discussed. The article concludes with a brief survey of various proposed applications for HTS bearings.

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Section: Bearing Dynamicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Superconducting bearings

Hull

2000

Supercond. Sci. Technol.

466

203

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“…Soon after, the deceleration rate of a superconducting lead sphere levitated in a magnetic field and cooled by helium was reported [17]. Proposals were made and prototypes were built for application of superconducting bearings in gyroscopes [18] and three phase electric motors [19]. Large-scale applications of superconducting levitation for transportation and rocket launchers emerged after niobium-titanium wires were made [20,21].…”

Section: Superconducting Levitationmentioning

confidence: 99%

AC Losses in Superconducting Magnetic Bearings

Siamaki¹

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Since the discovery of high-temperature superconductors, superconducting magnetic bearings have become an icon of applied superconductivity. Their ability to provide passive stable levitation/suspension has attracted much attention for industrial applications such as maglev trains, flywheel energy storage systems, and high speed electrical machines. Paihau-Robinson Research Institute has been working on the design and construction of a 22 kW, 30000 rpm homopolar superconducting motor for a hybrid aircraft propulsion system. Superconducting magnetic bearings seem to be a potential solution to overcome the speed limits imposed by friction and heat in mechanical bearings. Considering the lack of commercial availability of superconducting bearings, the Institute has decided to investigate the challenges involved in developing suitable bearings for ongoing and future projects. The focus of this thesis is to explore the development of suitable low-loss bearings from bulk high-temperature superconductors, and to develop suitable test methodologies that allow the properties and behaviour of high-temperature superconducting bearings to be explored. In order to accurately predict the behaviour of superconducting magnetic bearings, a precise knowledge about the non-linear voltage-current (E-J) relationshipis required for input to simulations. Unlike coated conductors, this cannot be achieved by transport measurements in superconducting bulks. In this thesis, a convenient non-destructive method based on levitation force decay in superconducting bearings is introduced and evaluated to map the non-linear electrical properties in superconducting bulks. Furthermore, fibre Bragg grating sensors are employed in an actual superconducting bearing environment to monitor temperature at the bearing surface. Accurate cryogenic temperature monitoring with large electromagnetic fields present is of great importance in practical applications, and is problematic with conventional electronic sensors. A barrier to commercial application is suspected to be the effects of inhomogeneous magnet, or superconducting, properties on the efficiency of bearings. The key drivers of this, AC loss mechanisms in superconducting bearings are investigated and a new analytical expression is proposed for hysteresis loss in superconducting bearings which takes magnetic field inhomogeneity, magnetic field periodicity, and loss surface distribution into account. This new expression is tested by performing spin-down experiments, and the results are found to be in good agreement. Lastly, a high-speed superconducting motor/generator demonstration is built, which sets a record for the fastest superconducting bearing made in New Zealand. This will enable applications such as flywheel energy storage systems, direct-drive generators and high speed microfans to be explored whilst also providing the opportunity to demonstrate key technology elements such as flux-pumped hightemperature superconducting field windings and low-loss high-speed bearings. AC loss mechanisms at kHz-rated rotational frequencies are also studied with this prototype. The results show that at high rotational frequencies the superconducting bulks are pushed into a resistive flux-flow regime, where AC losses are createdby an eddy-current-like mechanism. This thesis explores two phenomena of practical importance in superconducting bearings, and proves the principle of the application of superconducting bearings for ongoing and future projects in New Zealand.

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Cryocoolers for Superconducting Generators

Stautner

2020

Cryocoolers

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Three-phase motor with superconductive bearings

Cited by 8 publications

References 2 publications

Superconducting bearings

Superconducting bearings

AC Losses in Superconducting Magnetic Bearings

Cryocoolers for Superconducting Generators

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