Construction of the stator installed in the superconducting magnetic bearing for a 10 kWh flywheel

Kurihara

2012

JSDD

For the development of high speed flywheel rotation in a vacuum chamber, technology for establishing ultra low loss magnetic bearings and measures for preventing spillover vibration are necessary. For these purposes, tests on two rigs, one involving active magnetic bearings (AMBs) and the other, a medium-size flywheel, were conducted in the present study. With the former, a technique for reducing AMB loss was investigated. In the latter, many trials were carried out in an attempt to find a means for preventing spillover vibration. Based on the results, two important findings were made. First, AMB loss could be reduced to 1/6 of that in conventional control through the use of zero-power control and homo-polar magnetic poles. Secondly, flywheel rotation as high as 12,000 rpm was possible with no significant vibration through phase lead adjustment and the use of a stabilizing filter. Both these possibilities may be attributed to the very precise measurement of natural frequency and the damping ratio.

Section: Features Of the Test Rig And The Vibration Characteristic Anmentioning

confidence: 99%

Development of High Speed Flywheel Rotated in a Vacuum Chamber

Kurihara

2012

JSDD

“…This performance is much higher than the surface flux of about 0.5 T for Nd-Fe-B permanent magnets. Therefore, many new applications have been proposed, such as magnetic bearings used for a non-contact rotating machine, a magnetic separation system, compact NMR, and superconducting bulk motors that generate strong torque [2][3][4][5][6][7][8][9][10][11]. Here, in order to increase the magnetic field trapped by the bulk superconductor, an increase in the critical current density (J c ) and the size of the bulk is required.…”

Section: Introductionmentioning

confidence: 99%

Improvement of Superconducting Joint Properties for GdBa2Cu3Ox Bulk Superconductors Joined with ErBa2Cu3Ox Superconductor Using Local Melt-Growth Method

Takemura,

Sudo,

Sakafuji

et al. 2024

Materials

The important factors in obtaining a high-quality superconducting joint were investigated for the superconducting joint of a GdBa2Cu3Ox (GdBCO) bulk superconductor with sintered ErBa2Cu3Ox (ErBCO) using the local melt-growth method. REBCO (RE: rare earth) bulk superconductors can be used as strong magnets by magnetizing them, but they require large bulk sizes for their application. Although the superconducting joint presents a viable solution, many possibilities for property improvement remain, such as property degradation, depending on the joining direction. By varying the joining thermal conditions and confirming the elemental distribution, magnetization properties near the joined part and the effects of these on the joining properties are clarified, and a method for fabricating high-performance joined samples is obtained. Microstructure segregation was rarely observed at the center of the joined part regardless of the joining direction, and the superconducting properties were negligible and small. The Jc-B results are almost identical to those of the GdBCO matrix at a low field, confirming that the joined part minimally interferes with the superconducting current. Furthermore, by lowering the maximum temperature, shortening the holding time at the maximum temperature, and increasing the cooling rate, the region of mutual solid solution was reduced, and the Jc-B under the self-magnetic field was enhanced. These results contribute to the development of the superconducting joining method, a critical aspect of larger bulk superconductors.

Journal of Reinforced Plastics and Composites

“…1–3 Especially for the attitude control and energy storage flywheel (ACESF), not only is the speed of the rotor high but also the mass of the flywheel, especially the mass of the rotor are restricted strictly. 4,5 The flywheel rotor system, mostly supported by frictionless bearings such as magnetic bearings 6–11 or superconducting magnetic bearings, 12–20 generally consists of a metallic shaft, a rotor of composite materials and a hub that connects the rotor with the shaft. The total kinetic energy stored in the flywheel is given by Iω2/2, where I is the mass moment of inertia of the rotor around the spin axis and ω is the angular velocity of the rotor.…”

Section: Introductionmentioning

confidence: 99%

Hollow interference fitted multi-ring composite rotor of the superconducting attitude control and energy storage flywheel

Tang

Zhang

et al. 2013

The superconducting attitude control and energy storage flywheel is a kind of energy storage flywheel. With respect to this kind of flywheel, a rotor consisting of a hollow hub and three composite cylindrical rings in interference fitted state is presented to achieve high specific energy density. The hollow hub made of high strength steel 18Ni350 is used to change the distribution of centrifugal stress, reduce the maximum radial stress and to ensure the working gap of radial magnetic bearings and motor/generator is constant when the rotor rotates at a high rotary speed. Interference has been introduced between rings or ring and hub to avoid their delamination and eventually increase the maximum speed of the rotor. In order to find out the quantitative relationship among interference, tension force, radial pre-stress and so on, we analyzed the stress distribution of the rotor subjected to centrifugal loads, the initial stresses and displacements of the multi-rings rotor in interference fitted state by mathematical methods and finite element methods. Effects of these factors, such as interference between rings, thickness ratio of rings, different materials of rings and so on, are studied in detail to make clear how they affect the stress distribution of the interference fitted multi-ring composite rotor. The results of this study will give a useful hint for the design, test and manufacture of the composite rotor for the superconducting attitude control and energy storage flywheel.