JPH04217830A - Power storage system - Google Patents

Abstract

PURPOSE:To facilitate fabrication by employing a superconductor without forming into a linear member and to eliminate energy loss by magnetically levitating a flywheel. CONSTITUTION:A nonmagnetic and thermally conductive support 3 is mounted on a cryostat 1 and a superconductor 4 is arranged thereon. The superconductor 4 is composed, for example, of an yttrium superconducting material added with silver which exhibits pinning effect and the superconductor 4 is cooled by a cryogenic refrigerant 2 to exhibit pinning effect. A flywheel 8 comprising a tubular bottomed rotary body 9 and a permanent magnet 10 is disposed in a tubular body 6. The permanent magnet 10 is disposed oppositely to the superconductor 4 on the bottom of the rotary body 9 and the flywheel 8 is magnetically levitated rotatably by means of the superconductor 4. The magnetic levitation is stabilized by the pinning effect of the superconductor 4.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is a power generating system that uses a superconductor capable of exhibiting a pinning effect to magnetically levitate a flywheel in a rotatable manner to store electric power. Relating to a storage device.

(Prior art) Conventionally, energy storage devices have been known to have a structure in which a superconducting coil is fabricated by making a superconducting material into a wire, and a semi-permanent current is generated in the superconducting coil to store surplus power. It is being

Also, conventional power storage devices have been known that have a structure in which a flywheel is rotatably supported by a bearing, and surplus power is converted into mechanical rotational kinetic energy of the bearing-type flywheel and stored.

(Problem to be Solved by the Invention) By the way, power storage devices using superconducting coils have the advantage of less energy loss compared to power storage devices using bearing-type flywheels, but it is difficult to convert superconducting materials into wires. There is a problem in that manufacturing a superconducting coil itself is difficult. In addition, when storing a large amount of electricity, the diameter of the coil becomes larger and a strong rock is required to support the coil.
There is also an inconvenience in that the installation location is also restricted.

On the other hand, conventional power storage devices that use a bearing-type flywheel to store power by utilizing the mechanical rotational kinetic energy of the flywheel are easier to store large amounts of power than devices that use superconducting coils. However, because bearings are used, energy loss due to friction is inevitable, and the energy loss is much greater than that using superconducting coils. Recently, magnetic bearings and magnetic fluid bearings have been developed to reduce friction loss in bearings, but as long as bearings are used, energy loss due to friction is unavoidable, and increasing the moment of inertia will reduce the loss of energy. There is also the disadvantage that the friction loss increases.

The present invention was made in view of the above circumstances, and its purpose is to make it easy to manufacture even if a superconductor is used since it uses a bulk material, and to minimize energy loss even if a flywheel is used. The object of the present invention is to provide a power storage device that does not require bearings, which can be avoided.

(Means for Solving the Problems) In order to achieve the above-mentioned problems, the power storage device according to the present invention converts electrical energy into mechanical rotational energy, and a stator used for converting rotational energy into electrical energy. and a superconductor capable of exhibiting a pinning effect, and a permanent magnet disposed opposite to the superconductor, which is rotatably magnetically levitated by the superconductor, and which is magnetically levitated based on energization of the stator. The present invention is characterized by comprising: a flywheel that is rotated and causes the stator to generate power based on the rotation thereof.

(Function) According to the power storage device according to the present invention, the flywheel is magnetically levitated to be rotatable relative to the superconductor. The superconductor used in the present invention exhibits a pinning effect, so
Since the flywheel rotates stably and does not use bearings, loss of mechanical rotational kinetic energy can be reduced.

Therefore, electric power can be stored for a longer period of time than a conventional power storage device that utilizes the mechanical rotational kinetic energy of a bearing-type flywheel.

(Example) Hereinafter, an example of the power storage device according to the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of a power storage device according to the present invention, and in FIG. 1, 1 is a cryostat.

This cryostat 1 is made of a heat insulating material. This cryostat 1 stores a low-temperature refrigerant 2, such as liquid nitrogen. A support 3 made of a non-magnetic material and a good thermal conductor, such as a stainless steel plate, is provided on the top of the cryostat 1. A superconductor 4 is arranged on this support 3. For the superconductor 4, a material capable of exhibiting a pinning effect, such as a silver-added yttrium-based superconducting material, is used.

The superconductor 4 is constructed, for example, by fixing a tortoise-shaped individual 5 to a support 3 as shown in FIG.

The superconductor 4 is cooled by the low-temperature refrigerant 2 and becomes in a state where it can exhibit a pinning effect. In FIG. 2, the superconductor 4 is configured in a disk shape, but it may also be configured in an annular shape.

A cylindrical body 6 is installed on the top of the cryostat 1. A lid 7 is provided on the top of the cylindrical body 6. The inside of the cylindrical body 6 is hermetically closed by the lid 7. A flywheel 8 is disposed inside this cylindrical body 6. The flywheel 8 is generally composed of a rotating body 9 having a bottomed cylindrical shape and a permanent magnet 10. A permanent magnet 10 is disposed at the bottom of the rotating body 9, facing the superconductor 4. The flywheel 8 is rotatably magnetically levitated due to its superconductor 4. This magnetic levitation is stable due to the pinning effect of the superconductor 4.

The permanent magnet 10 is constructed by pasting a sector-shaped solid body 11 as shown in FIG. 3 in the shape of a disk or ring to the bottom of the rotating body 9.

As shown in FIG. 4, a squirrel-cage conductor 12 of a known induction motor is embedded in the inner wall of the rotating body 9 along the circumference of the inner wall. The so-called squirrel-cage rotor formed by the squirrel-cage conductor 12 and the stator 13 suspended from the lid 7 so as to face the rotor constitute a known outer rotor type induction generator motor. 12' is a rod-shaped conductor of the cage-shaped conductor 12. In the stator 13, a coil 15 is wound around a yoke 14. 16 is a lead wire drawn out from the coil 15. The lead line 16 is connected to a power system 18 via a known AC indirect power converter 17.

Thereby, the stator coil 15 is connected to the squirrel cage conductor 1
2, it plays the role of a known induction motor or induction generator. The inside of the cylindrical body 6 is evacuated using a vacuum pump (not shown), thereby reducing the air resistance when the flywheel 8 rotates, and reducing the air resistance of the flywheel 8 (the air resistance between the flywheel 8 and the air). loss of mechanical rotational kinetic energy due to friction) is reduced.

In the first embodiment, an induction motor or an induction generator is constructed by the squirrel-cage conductor 12 and the stator coil 15. However, the rotating body 9 is equipped with only a flywheel function, and The same purpose can be achieved by a synchronous generator-motor, provided that another known synchronous generator-motor is provided, and its shaft transmits power to the flywheel shaft via a clutch (not shown). The clutch is disengaged while the flywheel is free-running to prevent consumption of the mechanical rotational kinetic energy stored in the flywheel due to loss in the synchronous generator-motor.

In this case, the power system 18 and stator coil 15
They may be linked together via a known cycloconverter.

Furthermore, the same thing can also be achieved by using a DC brushless generator motor. In this case, the power system 18 and the stator coil 15 may be linked via a known buck/boost chopper and forward/reverse power converter.

FIG. 5 shows a second embodiment of the power storage device according to the present invention. I will only explain parts of it.

In this embodiment, a cryostat 1 is housed in a cylindrical body 6. An annular yoke 1 is provided on the inner wall of the cylindrical body 6.
A stator 13 consisting of a coil 15 and a coil 15 is provided. The flywheel 8 is composed of a cylindrical rotating body 9. A cage-shaped conductor 12 is attached to the outer peripheral wall of the rotating body 9. The rod-shaped conductor 12' is fitted into a fitting groove formed in the circumferential direction of the outer peripheral wall of the rotating body 9. The fitting groove extends in the direction in which the axis of the rotating body 9 extends. Here, the squirrel cage conductor 12 and the stator 13 constitute a known inner rotor generator motor.

In the case of this second embodiment, the mass of the rotating body 9 can be made lighter than that of the outer rotor type, so that the flywheel 8 can be rotated at high speed.

FIG. 6 shows a third embodiment of the power storage device according to the present invention, in which the flywheel is constructed in two stages to obtain a larger moment of rotational inertia than the flywheel 8 shown in the first embodiment. The structure is such that it can store electricity.

In this third embodiment, the flywheel 8 includes a cylindrical lower flywheel 20 and a bottomed cylindrical upper flywheel 2.
1, and the lower flywheel 20 and the upper flywheel 21 are integrally constructed via a connecting shaft 22. According to this configuration, the rotational moment of inertia can be increased without designing the flywheel to have a large diameter. Note that the remaining configuration is almost the same as that of the first embodiment, so the same components are given the same reference numerals and detailed explanation thereof will be omitted.

FIG. 7 shows a fourth embodiment of the power storage device according to the present invention. In this embodiment, disk-shaped permanent magnets 23 are disposed on the upper and lower surfaces of the lower flywheel 20, and on the circumferential surface thereof. While the cylindrical permanent magnet 23' is disposed, the superconductor 4 is disposed so as to surround the disc-shaped permanent magnet 23 and the cylindrical permanent magnet 23', and the pinning effect of the superconductor 4 is used to fly the It has a structure that prevents axial wobbling in the axial direction of the wheel 8 and in the direction perpendicular to the axis, and 24 is an inner cylinder in which the superconductor 4 is disposed, 25 is an outer cylinder constituting the cryostat, and 26 is its inner cylinder. This is a support that supports the inner cylinder.

8 to 10 show modifications of the fourth embodiment of the power storage device shown in FIG. 7, in which the lower flywheel 2
Instead of disposing the disk-shaped permanent magnets 23 on the top and bottom surfaces of 0, disks 27 and 28 are provided as shown in FIG. The magnets 30 and ring-shaped permanent magnets 31 whose outer peripheral surfaces are S-pole are arranged concentrically alternately with an interval H′, while the lower flywheel 20
Instead of providing the cylindrical permanent magnet 23' shown in FIG. 7 on the peripheral surface of the cylindrical permanent magnet 23' shown in FIG. 7, an annular permanent magnet body 29 is provided as shown in FIG. It is composed of a magnet 30' and an annular permanent magnet 31' whose outer peripheral surface is an S pole, and the annular permanent magnet 31' and annular permanent magnet 3
A non-magnetic ring plate 32 is provided between the lower flywheel 2' and the annular permanent magnet 30 and the annular permanent magnet 31 are arranged with an interval H in the longitudinal direction of the lower flywheel 20. be.

According to this modification, shaft wobbling can be prevented even better than the power storage device shown in FIG. 7.

In this modification, the ring-shaped permanent magnets 30 and 31 are embedded in the disks 27 and 28 so that their outer peripheral surfaces have different polarities, but the ring-shaped permanent magnets are embedded so that their outer peripheral surfaces have the same polarity. You may. Similarly, the outer peripheral surface of the annular permanent magnet body 29 may also have the same polarity. Further, the intervals H and H' are determined as appropriate.

In addition, in FIG. 9, the reference numeral 33 is an insertion hole through which the connecting shaft 22 is inserted.

Although the embodiments have been described above, the power storage device according to the present invention can also be used upside down.

Furthermore, the stator 13 may be constructed only from the stator coil 15 without using the yoke 14.

(Effects) Since the power storage device according to the present invention is configured as explained above, it is easy to manufacture the power storage device because there is no need to convert the superconductor into a wire even though it uses a superconductor. Moreover, even though a flywheel is used, no bearing is required at all, so energy loss can be avoided as much as possible.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of the power storage device according to the present invention, FIG. 2 is a plan view of the superconductor shown in FIG. 1, and FIG.
4 is a plan view of the rotating body shown in FIG. 1; FIG. 5 is a sectional view showing a second embodiment of the power storage device according to the present invention; FIG. 6 is a sectional view showing a third embodiment of the power storage device according to the present invention, FIG. 7 is a sectional view showing a fourth embodiment of the power storage device according to the present invention, and FIGS. 8 to 10 are This shows a modification of the fourth embodiment shown in Fig. 7. Fig. 8 is a sectional view corresponding to Fig. 7, and Fig. 9 is a disc attached to the upper surface of the lower flywheel shown in Fig. 8. 10 is a plan view of a disc attached to the lower surface of the lower flywheel shown in FIG. 8. FIG. 2...Liquid nitrogen, 4...Superconductor 8...Flywheel, 10, 12...Permanent magnet 13...Stator

Claims (1)

[Scope of Claims] A stator used for converting electrical energy into mechanical rotational kinetic energy and converting mechanical rotational kinetic energy into electrical energy, a superconductor capable of exhibiting a pinning effect, and the superconductor The superconductor has a permanent magnet arranged opposite to the superconductor, and is rotatably magnetically levitated by the pinning effect of the superconductor, and is rotated when the stator is energized, and the stator generates electricity based on the rotation. A power storage device characterized by comprising: a flywheel that generates;