JPH07509835A - energy storage device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] energy storage device field of invention The present invention relates to an energy storage device.

prior art Superconducting magnets have been developed for use as energy storage devices. However However, the main problem with the use of superconducting magnets is that energy is released very rapidly from the magnet. is dissipated and energy is supplied to the magnet very rapidly. This causes large stress and strain on the windings, which causes these windings to move, causing heat generation and It is to produce a rapid cooling condition.

A conventional energy storage device is disclosed in DE-C-4027546.

This device is designed to reduce stray magnetic fields and directs acting current in alternating directions, respectively. Carrying a rectangular array of superconducting coils (forming a “chessboard” pattern of magnetic fields) It is equipped with At large distances from the array, these fields cancel each other out. each other and reduce stray magnetic fields.

Summary of the invention According to one feature of the invention, the energy storage device is made of low Tc material. comprising an array of conducting electrical coils, the axes of which are substantially parallel; The electrical coils are laterally spaced in a non-overlapping manner and the electrical coils are operated in the same direction. carry current for use.

Using low Tc superconducting materials, energy A method of implementing an accumulator that overcomes the problem of rapid cooling and that also A method has been found that allows energy to be rapidly released and supplied. Actually Energy is required for a relatively short period of time, generally less than 1 second, and after dissipation , the device typically must be reenergized within about 10 seconds. In the device according to the invention This is possible.

A notable problem with the device disclosed in DE-C-4027546 is that the coil This means that there is a strong electromagnetic burst force.

For the burst forces present in DE-C-4027546, the present invention The return field at the outer radius of the nod induces a Lorentz force, which is compressible This helps support the burst force at the inner radius.

Yet another advantage is that the magnetic Being able to assemble the rail. Furthermore, a series followed by a very small radius of curvature If a continuous trajectory is theoretically required, it may not be possible to achieve it in practice with a continuous trajectory. profile. Conductors are exposed to stress near sharp bends. Concentrated and localized strains may occur, increasing the risk of wire movement under e/m forces. Ru. For example, in some environments "box-type permanent" using "clad" coils may be It is effective to shield the array using long-term magnets.

Each coil is only mechanically supported against e/m forces and thermal strain. Ru. Since the shape of the individual elements is usually cylindrical, the windings are free from the possibility of discontinuities. Instead, it can simply be clamped and "glued" in place. Each The short continuous length of the coil is due to discontinuities due to thermally induced volume changes in the coil. Reduce distortion changes. Small perturbations create cascading poles along the strain energy gradient. It is possible to design an array that optimally distributes strain energy without releasing micromotion. The impact is quite large.

The present invention allows the system to be flexible to match the load time of charge discharge demands. can be connected. For example, to partially extract energy from the entire array. An even faster method is to extract all the energy from a certain section rather than Partial discharge can be achieved. This array solution is designed to prevent damage to the system. When parallel connections of subsets of arrays are used to provide Tolerating minor defects. During operation, elements can be replaced individually. Ru.

The geometry of the array of coils can be used to activate protection circuits and active protection systems. Suitable for interconnecting early quench sensors to trigger.

Arrays of coils are easier to install cooling channels than large one-piece windings. It can give you many options to choose from. Cooling aids quench protection It can be increased locally like this.

To minimize heat generation within the superconducting filament of the LTSC composite during changes in the magnetic field requires a very small filament diameter. standard filament conductor The wire has filaments approximately 70 microns in diameter. In the case of micro SMES requires a 2 micron diameter filament.

Co-processing niobium titanium 2 micron filament in steel matrix conductor In this case, the conductor is very susceptible to breakage during withdrawal. These folds are Occurs most often as the body approaches its final size, hence the cost of work Relaxing length requirements is a key factor in cost savings (joint Array joints can be placed in low magnetic field regions, making them efficient to form. can).

In a coil array, "more magnetic flux passes through more turns" means Increase the inductance per unit volume of the stem. This is the unit inductor Easy to adapt and shield with low cooling cost per tank This means that it has a compact structure (because the rate of change of the magnetic field is rapid). (Prevention of fringe magnetic field hazard is essential).

The coil is formed of a conventional low temperature (Tc) superconductor, and the superconductor of this coil is a liquid It is at the temperature of body helium and can be applied to superconducting materials at higher temperatures, but In general, it is only applicable to materials that are superconducting at liquid nitrogen temperatures or lower. Wear.

These coils can be connected in series or in parallel to the input and output connections. can. The parallel arrangement allows selective use of the electrical coils and thus , partial energy release can be achieved if necessary.

In some cases, some or all of the coils may be nested with additional coils within them. can be done.

Brief description of the drawing Hereinafter, an example of an energy storage device according to the present invention will be described in detail with reference to the accompanying drawings. Explain.

Figure 1 is a cross-section of the device showing the coil arrangement with the support and cryogenic structure omitted. It is a diagram.

FIG. 2 is a longitudinal cross-sectional view of one of the coils shown in FIG.

Figure 3 is a graph showing the variation of the magnetic field profile along the radius of the device shown in Figure 1. be.

FIG. 4 shows the radius R of the 7 coil array and 37 coil array shown in FIG. This is a graph showing the magnetic field profile due to a single element coil along the Ru.

Figure 5 shows the radial direction for a single large coil of equal size to the coil shown in Figure 1. It is a figure showing the magnetic field profile of the direction.

FIG. 6 shows the radial magnetic field profile of the array shown in FIG. FIG.

FIG. 7 is a diagram showing a magnetic field profile for the inner circumference of the central coil in FIG. 1.

FIG. 8 is a diagram showing a magnetic field profile with respect to the outer circumference of the central coil in FIG. 1.

FIG. 9 shows the magnetic field profile for the inner circumference of the outer coil of the array shown in FIG. It is a diagram.

Figure 1O is a diagram showing the magnetic field profile for the outer circumference of the outer coil shown in Figure 1. be.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 shows a hexagonal array of 37 coils 1 to 37. each of the array The individual coils have the dimensions shown in longitudinal section in FIG. The inner radius is 0.9 m, and the outer radius is 1. Om, and the length is 2 m. this To explain the example, what is the current density in the winding? , 5 x 10" Am-" Ru. These coils are wound in a cryogenic machine from conventional low Tc copper wire in a mold. These are omitted for clarity of illustration. The coils are nested inside Additional coils may be included, but are not shown in this example.

For this coil system, we use Ampere's law and the number for the conductor volume. The magnetic field is calculated using known techniques including value integration. These calculations are To ensure that minutely accurate results are obtained, there are many different repeated with step size.

The stored energy is calculated as the square of the magnetic field strength for all the volume of space where the magnetic field is perceivable. Calculated from integrals. To check the accuracy, try this in different spatial limits for the integral: These calculations were repeated.

To illustrate the development of this example system, we performed calculations for the following: went.

■, Single coil element.

2. Seven such elements in a hexagonal array (labeled l to l in Figure 1) element numbered 7).

3. Complete array of 37 coils shown in Figure 1.

4. The outermost coils (numbers 9, 10, 18, 15, 16, 23, etc.) A similar array of 37 coils weakened by reducing the winding cross section. Reduction of winding cross section The smaller diameter was achieved by changing the inner winding radius from 0.9m to 0.93m. .

5. A single large piece with an inner radius of 6.9 m, an outer radius of 7 m, and a length of 2 m. Kina coil 38゜This coil is larger than the small element coil size. When viewed from a distance, it can be shown to be equivalent to an array of 37 coils and is actually an array of 37 coils. Energy calculations can be shown to have approximately the same stored energy.

Figure 3 shows the magnetic field profile along radius R of an array of 37 identical coils l or 37. file.

Figure 4 shows a single element coil for 7 arrays and 37 arrays, respectively. It shows three similar profiles 40, 41 and 42 superimposed against ( Cases 1, 2 and 3 above).

FIG. 5 shows the magnetic field profile for a single coil 38 of equal size for comparison. (Case 5).

Figure 6 shows the magnetic field profile of array 37 with weakened outer members (case S4).

These arrays have a magnetic field profile similar to a large single coil, but with It is evident that there is a small region of negative magnetic field near the outer edge of the line. This border In distant arrays, the return flux of adjacent coils splits the magnetic field within a particular coil. reduced to a more moderate level than would be the case with separated coils. outside of the coil At the radius, the return flux enhances the negative magnetic field, forming a region of strong negative magnetic field. Ru. At the edges of the array, these mechanisms do not occur. Inner turn of outer coil The (positive) field strength at the wire radius is unacceptable (a burst force is generated) (or, in the case of superconducting windings, because the current carrying capacity of the conductor is reduced) , as shown in Figure 6, the outer coil is slightly weakened (this can be reduced by I can do it.

7 and 8 show that the coils at or near the center of the array (e.g., coils 1-7) (1) shows changes in the direction of the magnetic field strength near the inner and outer peripheries. this magnetic field The changes are small and, as expected, have six-fold symmetry. Figure 9 and IO , a coil at the edge of the array (e.g. coil 9.15.20.25.30 or 35) is shown. Here the changes are very large It is something. Its detailed morphology is known to be based on the shape of the coil.

Relatively long coils such as these individually have a uniform magnetic field profile, The result is a smooth curve dominated by first-order changes. short hoop (rings) have almost no uniform magnetic field and therefore have no advantage over the coils at the edges. The azimuthal magnetic field profile produced by the Having both minutes.

These detailed differences do not affect the principle of the present invention and are In this case, the current carrying capacity is determined by the maximum magnetic field value, but the current carrying capacity of the hoop in the conductor is Stress is determined by the average value obtained by averaging its surroundings. I would like you to remember that.

Stress in a conductor can be calculated from Lorentz forces. intermediate plane For a conductor in This is directed radially outward. In the absence of other supports, this force is S=J , R, B, due to the hoop stress of the conductor.

Insulation, cooling channels and other conductors, if additional supports are provided. Material forces with low elastic modulus such as therefore, there is still substantial hoop stress on the conductor. appear.

The present invention can provide two advantages for electromagnetic force support. First, small Low hoops from a given Lorentz force due to the use of a coil with a small winding radius Torres can be obtained directly. Second, the return flux from adjacent coils produces a compressive component. This is a superconducting compound in which the conductor is brittle in a compliant matrix. This is particularly desirable when the object is a physical object. In this way, the coils serve as mutual supports. Tasu. This structure creates stiffness without weight in space and other fields of mechanical engineering. similar to the "honeycomb" compound used to

The table below lists the characteristics and equivalents of various aspects in the coil system. This summarizes the characteristics of a single coil.

Coils 1 to 37 are connected in series or parallel to the terminals and the device is connected via a switch. It can be connected to an electric circuit. The operation of this switch is similar to that of traditional storage devices. It is the same as when

Heisei Year Month Day

Claims (5)

[Claims] 1. comprising an array of superconducting electrical coils made from a low Tc material, an axis of said coils; are substantially parallel and the coils are laterally spaced in a non-overlapping manner. Features an energy storage device. 2. 2. The device of claim 1, wherein the electrical coils are arranged in a hexagonal array. 3. 3. A device according to claim 1 or 2, wherein the coils are electrically connected in parallel. 4. The electric coil of claim 1 is made of a material that is superconducting at liquid helium temperatures. The device according to any of the above. 5. 5. Each coil according to claim 1, wherein each coil has an outer diameter of substantially 2 m. Device.