JPH06303738A - Flywheel generator - Google Patents

Abstract

PURPOSE:To provide a flywheel generator which has sufficient levitation performance and whose electrical characteristics are not deteriorated by magnetic bearings which are composed of high temperature superconductors. CONSTITUTION:A generator has a flywheel 1, pole permanent magnets 1-1, levitation magnets 2-1 and magnetic bearings 2 and 3 which are comosed of levitation bulks 3-1 made of superconducting material and are positioned so as to face the levitation magnets 2-1. In this generator, the magnetic bearings 2 and 3 are so privided as to have outer diameters smaller than the center diameters of the pole permanent magnets. With this constitution, a large gap can be provided between a magnetic bearing levitation part and a stational part and the a large size flywheel generator which has the magnetic bearings composed of the high temperature superconductors can be obtained and, further, the disturbance of a magnetic field can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flywheel generator equipped with a magnetic bearing using a high temperature superconductor.

[0002]

2. Description of the Related Art A flywheel generator is an energy storage system that converts electric energy into rotational energy of an object having a large moment of inertia and outputs and outputs electric power. In the conventional flywheel generator, a flywheel is attached to an ordinary salient-pole generator and is operated in the atmosphere using ordinary bearings.

In recent years, flywheel generators using magnetic bearings have been designed, and a structure capable of reducing mechanical loss was devised. The flywheel generator shown in FIG.
National Conference of the Institute of Electrical Engineers of Japan (NO938 8MWh class high temperature superconducting levitation flywheel power storage system conceptual design)
It was proposed to. As a structure, a flywheel is installed under an ordinary generator, and the whole structure is supported by magnetic bearings.In addition to the complicated structure around the generator main body, the diameter of the generator main shaft is small and the power generation efficiency is high. It was a structure that could be kept low.

[0004]

When a normal bearing is used in the flywheel generator, the larger the weight of the flywheel, the larger the energy storage capacity, but conversely the mechanical loss becomes large. In addition, when operating in the atmosphere, the wind loss increases and the efficiency deteriorates. Therefore, a method of using a magnetic bearing for the bearing and placing the generator structure in a vacuum was conceptually considered, but sufficient levitation performance could not be obtained only with the repulsive force of the magnetic bearing, which makes the generator larger. It is necessary to devise a structure to compensate for this.

An object of the present invention is to have sufficient levitation performance,
It is an object of the present invention to provide a flywheel generator using a high-temperature superconductor for a magnetic bearing that does not impair electrical performance by the magnetic bearing.

[0006]

A flywheel generator according to the present invention comprises a flywheel, a permanent magnet for magnetic poles, a levitation magnet, and a levitation bulk consisting of a high-temperature superconductor that faces the levitation magnet. The magnetic bearing is arranged such that the outer diameter of the magnetic bearing is equal to or smaller than the central diameter of the permanent magnet for the magnetic pole.

The flywheel generator of the present invention is operated by setting the ambient air pressure of the rotor between 0.1 atm and 0.4 atm.

The flywheel generator of the present invention is equipped with a suction type magnetic bearing consisting of a normal conducting coil above the levitation magnet.

[0009]

By increasing the gap between the floating portion of the magnetic bearing and the fixed portion, it is possible to increase the size of the flywheel generator using the magnetic bearing provided with the high temperature superconductor, and to reduce the disturbance of the magnetic field.

[0010]

EXAMPLE FIG. 1 shows an example of a flywheel generator using the magnetic bearing of the present invention.

A flywheel 1 serves to store energy in the form of rotational energy. 1-1 is a magnet for a magnetic pole, which is composed of a permanent magnet. Reference numeral 2 denotes a flywheel floating portion, which includes a floating magnet 2-1 made of a permanent magnet. Reference numeral 3 denotes a stationary bearing, which includes a high temperature superconducting bulk 3-1. Reference numeral 4 denotes a radial backup bearing. When the rotating shaft 1-2 is displaced, the rotor 1A is fixed to the stator 6A by the magnetic attraction force of the magnetic pole magnet 1-1.
To be attracted to. A backup bearing 5 in the thrust direction also serves to move the rotor in the axial direction. Reference numeral 6 denotes a stator coil, which inputs and outputs electric power with the outside. 7-1 and 7-2 are vacuum vessels, which are hermetically sealed vessels for keeping the entire generator in vacuum. 8-1 and 8-2 are liquid nitrogen pipes, and liquid nitrogen 1
Plays a role of supplying 0. The flywheel generator of the present invention comprises the above-mentioned main components.

Initially, the rotor 1A is axially lifted by the backup bearing 5 from the position shown in the figure. After the liquid nitrogen 10 is supplied to the high temperature superconducting bulk 3-1 and is cooled to the critical temperature or lower to be in the superconducting state, the backup bearing 5 lowers the rotor 1A. Superconducting bulk 3
As the levitation magnet 2-1 approaches -1, the magnetic force lines try to enter the superconducting bulk 3-1.
Except for some magnetic force lines entering the superconductor depending on the weight of A, the pinching effect of the superconductor on the magnetic force lines causes only a slight intrusion of the magnetic force lines. A force is generated, and the flywheel floating portion 2 floats in the air and stops.

After this state, the backup bearing 5 in the thrust direction is separated from the rotor 1A so that the rotor 1A is completely in the air. When there is surplus power in the system, the stator coil 6 is excited by using an inverter to rotate the rotor 1A and store surplus energy as the rotational energy of the flywheel levitation unit 2.

On the contrary, when the electric power in the system is insufficient, the rotational energy of the flywheel floating portion 2 is converted into electric energy.

As described above, in the flywheel generator of the present invention, the windage loss was reduced by putting the generator structure in the middle. Further, during rotation, the rotor 1A was in a state of being completely floated in the air, and the mechanical loss due to the friction of the bearing portion was set to 0. Further, the flywheel floating portion 2 and the fixed-side bearing 3 may have a disk shape as shown in FIG. 1 or a ring shape to obtain the same effect. As for the mounting position of the backup bearing 4 in the radial direction, the same effect can be obtained even if it is mounted not only on the lower side of the rotor as shown in FIG.

In the embodiment of the present invention shown in FIG. 1, the outermost diameter of the superconducting bulk 3-1 is arranged to be equal to or less than the center diameter of 1. The permanent magnet of the magnetic pole magnet 1-1 forms a magnetic circuit by penetrating the permanent magnet and moving around. Further, the permanent magnet of the levitation magnet 2-1 also has a magnetic field penetrating the permanent magnet in such a manner that the magnetic field rotates 90 degrees with respect to an axis perpendicular to the paper surface.
A magnetic circuit is formed in the same manner as in the case of. Since the adjacent permanent magnets of the magnetic pole magnet 1-1 have magnetic poles in opposite directions, the magnetic pole magnet 1-1 and the levitation magnet 2
When -1 is located close to each other and the magnetic fields interfere with each other, the magnetic field is disturbed in the circumferential direction. In this embodiment, the magnetic field of the magnetic pole magnet 1-1 and the magnetic field of the levitation magnet 2-1 and the superconducting bulk 3-1 are small in interference, and the magnetic field of the levitation magnet 2-1 and the superconducting bulk 3-1 is levitated. Can be used efficiently. Further, the magnetic field of the magnetic pole magnet 1-1 is less disturbed, which is electrically advantageous. Further, as compared with the conventional example shown in FIG. 3, by placing the magnetic pole magnet 1-1 on the outer peripheral side of the flywheel, the structure can be integrated with the flywheel, which is structurally simple. Also, as the nature of the generator, if the rotation speed and output are constant, (rotor radius) ² × (iron core product thickness) ∝ 1 / (gap magnetic flux density) / (stator ampere conductor), the gap magnetic flux density is It can be small, and the efficiency as a generator is good.

In another embodiment of the invention, the air pressure around the rotor was set from 0.1 atm to 0.4 atm. The fixed-side bearing 3 is supplied with liquid nitrogen from the outside, but the upper surface of the container of the fixed-side bearing 3 does not have a lid, and when the liquid nitrogen liquid surface is directly exposed to vacuum, the lid thickness 2 can be brought closer to 3. Becomes easier,
A larger floating force can be obtained, which is advantageous for increasing the size of the rotor.

However, when the stationary bearing 3 is not of a hermetic type, the liquid nitrogen evaporates because the balance with the vapor pressure is maintained when the surroundings are evacuated. At this time, the temperature of the liquid nitrogen is lowered because the necessary heat of evaporation is removed. The higher the degree of vacuum in the surroundings (the lower the atmospheric pressure), the smaller the windage loss, which is advantageous. However, nitrogen has a triple point around 100 torr, and a vapor pressure lower than the triple point cannot be achieved. Under these conditions, when operating the flywheel generator of the present invention, setting the ambient pressure from 0.1 atm to 0.4 atm reduced wind loss and increased efficiency. If it is less than 0.1 atm, it cannot be used because it does not become liquid nitrogen, and if the pressure is more than 0.4 atm, it cannot be used because of large air resistance, so the above range is set.

In the embodiment of FIG. 2 of the present invention, a suction type magnetic bearing 15 using a normal conducting coil that can move up and down is provided above the rotor.
Was set up. In the structure of FIG. 1, the bearing on the side of the stator is located only under the rotor and supports the weight of the rotor 1A only by the magnetic repulsive force. In the case of the structure of FIG. 2, a large thrust load that can be supported can be taken, and stability during rotation can be improved. Further, when the thrust load is small, the gap between the flywheel floating portion 2 and the fixed side bearing 3 is large, the liquid nitrogen container of the fixed side bearing 3 can be sealed, and the surroundings can be made high vacuum, thus reducing wind loss. be able to. If the thickness of the container can be increased, the stationary bearing 3 can have a stronger structure. The upper magnet is the levitation magnet 2-1.
Since it is on the suction side, it has a strong structure against electromagnetic suction Mag Pull force.

[0020]

According to the flywheel power generation of the present invention,
The flywheel generator can be enlarged by increasing the gap between the magnetic bearing floating part and the fixed part. Further, the flywheel generator can be provided with a magnetic bearing in which the disturbance of the magnetic field is small.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a flywheel generator shown as an embodiment of the present invention.

FIG. 2 is a schematic explanatory diagram of a flywheel generator shown as another embodiment of the present invention.

FIG. 3 is a schematic explanatory view of a conventional flywheel generator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Flywheel ring, 1-1 ... Magnet for magnetic poles, 2 ... Flywheel floating part, 2-1 ... Levitation magnet, 3 ... Fixed side bearing, 3-1 ... High temperature superconducting bulk, 4
... Radial direction backup bearing, 5 ... Thrust direction backup bearing, 6 ... Stator coil, 7-1, ... Vacuum container, 8-1,2 ... Liquid nitrogen piping, 9 ... Inverter,
10 ... Liquid nitrogen, 11 ... Vacuum pump, 12 ... Thrust direction active magnetic bearing, 13 ... Radial direction active magnetic bearing, 14 ... Auxiliary bearing, 15 ... Suction type magnetic bearing, 16 ... Suction steel plate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 000006655 Nippon Steel Corporation 2-3-6 Otemachi, Chiyoda-ku, Tokyo (71) Applicant 000180368 Shikoku Electric Power Co., Inc. 2-5 Marunouchi, Takamatsu City, Kagawa Prefecture (71) Applicant 000173784 2-8, Hikarimachi, Kokubunji, Tokyo 38 (71) Applicant 000000974 Kawasaki Heavy Industries, Ltd. 3-1-1 Higashikawasaki-cho, Chuo-ku, Kobe-shi, Hyogo (74) ) Above four attorneys Katsuo Ogawa (1 outside) (72) Inventor Hiroshi Morimoto 3-1-1 1-1 Saiwaicho, Hitachi City, Ibaraki Hitachi Ltd. Yasuhiro Yasaka (72) 3-1-1, Saiwaicho, Hitachi, Ibaraki Stock Company Hitachi, Ltd. Hitachi factory (72) Inventor, Keiji Saito 3-1-1, Saiwaicho, Hitachi, Ibaraki Hitachi, Ltd. Hitachi Factory (72) Inventor Hirokazu Suzuki 1-3-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Tokyo Electric Power Company (72) Inventor Masahiko Endo 1-3-1, Uchisaiwai-cho, Chiyoda-ku, Tokyo Tokyo Electric Power Company Co., Ltd. (72) Inventor Kiyoshi Goto 1-3-3 Uchisaiwaicho, Chiyoda-ku, Tokyo Tokyo Electric Power Co., Inc. (72) Inventor Masato Murakami 1-14-3 Shinonome, Koto-ku, Tokyo International Superconducting Industrial Technology Foundation Research Center Superconductivity Engineering Laboratory (72) Inventor Hiroshi Takaichi 1-14-3 Shinonome, Koto-ku, Tokyo International Superconductivity Research Institute of Technology Superconductivity Engineering Laboratory (72) Inventor Naoki Koshizuka Koto Tokyo 1-14-3 Shinonome Ward International Superconductivity Industrial Technology Research Center Superconductivity Engineering Laboratory (72) Inventor Hiroyuki Fujimoto 1-14-3 Shinonome Foundation Kosuper Ward International Superconductivity Industrial Technology Research Center Superconductivity Engineering In the laboratory (72) Inventor Akihiro Fuji Koto-ku, Tokyo Shinonome chome 14 No. 3 Foundation International Superconductivity Technology Center, more than conductivity engineering in the Institute

Claims (3)

[Claims] 1. A flywheel 1, a magnetic pole permanent magnet 1-
1, a levitation magnet 2-1 and a levitation bulk 3-consisting of a high-temperature superconductor that faces the levitation magnet 3-
A flywheel generator characterized in that the magnetic bearings (2) and (3) are arranged such that the outer diameters of the magnetic bearings (2) and (3) are equal to or smaller than the center diameter of the magnetic pole permanent magnets. 2. The generator according to claim 1, wherein
A flywheel generator characterized in that the ambient air pressure of the rotor is set between 0.1 atm and 0.4 atm. 3. The generator according to claim 1, wherein
A flywheel generator characterized in that a suction type magnetic bearing composed of a normal conducting coil is provided above the levitation magnet 2-1.