Superconducting bearings

Hull, J.R.

doi:10.1088/0953-2048/13/2/201

Cited by 466 publications

(227 citation statements)

References 159 publications

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“…Detailed experiments have been performed on melt-textured-grown ͑MTG͒ YBCO and RBCO (R denotes a rare earth element such as Nd, Sm, Gd, Eu, Dy, Ho, Er, Tm, Yb, Lu, and La͒, thin films, as well as granular samples. 4,[12][13][14][15][16] For MTG YBCO and RBCO samples, the force curve is usually asymmetrical, i.e., the absolute value of the attractive force is smaller than the maximum repulsive force ͉F a,max ͉ϽF r,max . 16 For thin films, the force curve is almost symmetrical ͉F a,max ͉ϷF r,max , 17 while for granular samples, the attractive force is hardly present.…”

Section: Introductionmentioning

confidence: 99%

“…Experimental results for vertical stiffness, lateral stiffness and cross stiffness have been presented. 4,12 In addition to these, the geometry and properties of the PM also affect the levitation force. The size and shape of the PM, the homogeneity and the temperature dependence of the PM magnetization have been shown to influence the levitation force.…”

Section: Introductionmentioning

confidence: 99%

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Calculation of the hysteretic force between a superconductor and a magnet

Qin

Liu

et al. 2002

Phys. Rev. B

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The magnetic levitation forces exerted on a high-temperature superconducting ͑HTS͒ disk by a cylindrical permanent magnet ͑PM͒ are calculated from first principles for superconductors with finite thickness. The current j( ,z) and field B( ,z) profiles in the HTS in the nonuniform magnetic field generated by the PM are derived. The levitation force depends nonlinearly on the critical current density j c and on the thickness of the HTS. The flux creep is described by a current-voltage law E( j)ϭE c ( j/ j c ) n , from which we show that the levitation force depends on the speed at which the PM approaches or recedes from the HTS, which accounts for the experimentally observed force creep phenomenon. The stiffness of the system is derived by calculating minor force loops. The numerical results reproduce many of the features observed in experiments.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Calculation of the hysteretic force between a superconductor and a magnet

Qin

Liu

et al. 2002

Phys. Rev. B

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“…This superconductor has highest critical temperature about 94K. Because superconducting properties of the Y123, Y358, and Y257 can be performed in liquid nitrogen, this cheap cryogenic medium makes the materials promising in many fields such as superconducting magnetic bearings (Jiqiang et al, 2012), superconducting electric motors (Hiroyuki and Yuichi, 2001), magnetic separation devices (Oka et al, 2013), non-contact transport systems (Smith and Jr. Dolan, 2013), flywheel energy storage systems (Arai et al, 2013) and permanent magnets with high trapped field (Liu et al, 2011) operating above 77K (Moon and Chang, 1990;Hull, 2001).…”

Section: Introductionmentioning

confidence: 99%

Electrical properties and crystal structure of Y123, Y358 and Y257/Y211 composite bulk superconductors

Kruaehong¹

2014

Int. J. Phys. Sci.

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The Y123, Y358 and Y257 bulk superconductors mixed with various ratio of non-superconducting Y211 (Y 2 BaCuO 5 ) were synthesized by solid state reaction. The physical properties of pellets were investigated by d.c. four-probes measurement. The crystal structure was determined using powder X-ray diffraction and the characteristic peaks were determined using the Rietveld full-profile analysis method. Results showed that the T c onset and T c offset decreased with the increasing of Y211 doping. The samples consist of both superconducting phase and the non-superconducting phase. The lattice parameter of Y211 doped samples showed lower c direction than pure samples. The superconducting phase decreased with increasing Y211 content. The non-superconducting phases consists of Pccm (Ba 2 Cu 3 O 6) and Im-3m (BaCuO 2 ) respectively. According to the percentage of superconducting phase, the anisotropy increased with Y211 contents.

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“…The SFES using a superconductor magnetic bearing (SMB) [1,2] is a environment-friendly utility without chemicals and has higher energy storage efficiency than other type flywheels using a mechanical ball bearing and a magnetic bearing. The energy loss characteristics and efficiency of a SFES using SMB have been evaluated in many studies [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Experimental Estimation on Magnetic Friction of Superconductor Flywheel Energy Storage System

Lee¹,

Han²,

Park³

2011

Journal of Magnetics

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This study estimated experimentally the loss distribution caused by magnetic friction in magnetic parts of a superconductor flywheel energy storage system (SFES) to obtain information for the design of high efficiency SFES. Through the spin down experiment using the manufactured vertical shaft type SFES with a journal type superconductor magnetic bearing (SMB), the coefficients of friction by the SMB, the stator core of permanent magnet synchronous motor/generator (PMSM/G), and the leakage flux of the metal parts were calculated. The coefficients of friction by the stator core of PMSM/G in case of using Si-steel and an amorphous core were calculated. The energy loss by magnetic friction in the stator core of PMSM/G was much larger than that in the other parts. The level of friction loss could be reduced dramatically using an amorphous core. Energy loss by the leakage magnetic field was small. On the other hand, the energy loss could be increased under other conditions according to the type of metal nearby the leakage magnetic fields. In manufactured SFES, the rotational loss by the amorphous core was approximately 2 times the loss of the superconductor and leakage. Moreover, the rotational loss by the Si-steel core is approximately 3~3.5 times the loss of superconductor and leakage.

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Superconducting bearings

Cited by 466 publications

References 159 publications

Calculation of the hysteretic force between a superconductor and a magnet

Calculation of the hysteretic force between a superconductor and a magnet

Electrical properties and crystal structure of Y123, Y358 and Y257/Y211 composite bulk superconductors

Experimental Estimation on Magnetic Friction of Superconductor Flywheel Energy Storage System

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