JP2000277321A - Superconducting coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superconducting coil which can provide uniform current share between a plurality of superconducting conductor wires connected in parallel, even if AC currents are passed through the wires. SOLUTION: This superconducting coil includes groups G1 and G2 of pancake coils P1, P2, P3 or P4, P5, P6 of superconducting conductor wires 1, 2, 3 which are sequentially stacked in the axial direction but are different in their radially- overlapped order and which are dislocated in the radically-overlapped order between the wires 1, 2, 3 at transition parts T1, T2 of the coils P1, P2, P3, P4, P5, P6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting coil for high-speed excitation and demagnetization used for energy storage and magnetic field applications, and more particularly to a superconducting coil in which a plurality of superconducting wires connected in parallel have a uniform current sharing. For coils.

[0002]

2. Description of the Related Art FIG. 2 is a one-side sectional view showing the structure of a conventional superconducting coil. The three superconducting wires 1, 2, 3 connected in parallel are superposed in the radial direction (the left-right direction in FIG. 2),
Two pancake coils p1, p2, p3, p4, p5, and p6 wound in a disk shape with the left side of FIG. 2 as the central axis are laminated in the axial direction (vertical direction in FIG. 2). The superconducting wires 1, 2, and 3 of the first-layer pancake coil p1 are wound from the terminal U for external connection of the superconducting coil to the inner-diameter side, starting from the outer-diameter side. Coil p2
The superconducting wires 1, 2 and 3 are wound around the inner diameter side and are wound toward the outer diameter side. In addition, the start of winding of the pancake coil p2 of the second layer and the end of winding of the pancake coil p1 of the first layer are connected via a crossover portion t1 which extends in the axial direction. Hereinafter, the odd-numbered pancake coil p
The superconducting wires 1, 2, 3 of 3 and p5 are wound on the inner diameter side starting from the outer diameter side, and the odd-numbered pancake coils p
3, p5, and the pancake coil p2 in the previous layer
The winding end of p4 is connected to each other via a transition portion t2 which is passed in the axial direction. Also, the superconducting wires 1, 2, and 3 of the even-numbered pancake coils p4 and p6 are wound to the outer diameter side starting from the inner diameter side, and the winding of the even-numbered pancake coils p4 and p6 is started. The winding ends of the pancake coils p3 and p5 of the front layer are connected to each other via a transition portion t1 that extends in the axial direction. The end of the winding of the pancake coil p6 of the sixth layer is connected to another terminal u for external connection of the superconducting coil.

In FIG. 2, a current flows from terminals U and u to respective superconducting wires 1, 2 and 3 in parallel, and a magnetic field is formed around the superconducting wires. The conventional example shown in FIG. 2 is a case where the number n of superconducting wires wound in a pile in the radial direction is three, and the number n of parallels generally becomes a plurality of two or more. In some cases, n is four or six. In addition, the number N of layers of the pancake coil may be generally two or more.

[0004]

However, when the conventional superconducting coil as described above is applied to an AC device, there is a problem that the current sharing of a plurality of superconducting wires wound in a radially overlapping manner is not uniform. there were.

That is, in a superconducting coil such as a nuclear magnetic resonance type tomographic imaging apparatus (MRI) or a linear motor, the current applied to the superconducting wire is direct current. The current sharing of the wires did not become uneven. However, recently, developments have been made to apply superconducting coils to AC devices such as for energy storage and transformers. When an alternating current is passed through the superconducting coil of FIG. 2, the superconducting wires 1, 2, and 3 have different winding radii, and thus have different inductances. Superconducting wire 1 has the smallest winding radius, and superconducting wire 3 has the largest winding radius. Therefore, the current values flowing through the superconducting wires 1, 2, 3 differ. If the unbalanced portion of this current becomes a circulating current and flows through the superconducting coil, the AC loss accompanying the drift increases, or the transition from the superconducting state to the normal conducting state becomes easy when the critical current value is exceeded. It may not work.

[0006] In order to improve the unbalance of the current sharing of each superconducting wire in the superconducting coil applied to the AC equipment as described above, it is necessary to equalize the inductance of each superconducting wire. In superconducting coils,
2. Description of the Related Art A technique for displacing a superconducting wire in order to equalize the inductance of each superconducting wire has been conventionally known.

However, in the case of a pancake type superconducting coil, the inductance of each superconducting wire is made uniform in order to improve the imbalance in current sharing of each superconducting wire, and the uniformity of this inductance is realized. The specific configuration has not been studied conventionally. An object of the present invention is to provide a superconducting coil in which current sharing of a plurality of superconducting wires connected in parallel becomes uniform even when an alternating current flows.

[0008]

According to the present invention, there is provided a pancake coil in which a plurality of superconducting wires connected in parallel are superposed in a radial direction and wound in a disk shape. Are laminated in the axial direction, the superconducting wire of the first-layer pancake coil is wound to the inner diameter side starting from the outer diameter side, and the superconducting wire of the second-layer pancake coil is wound to the inner diameter side. As it is wound to the outer diameter side as the winding start,
The start of winding of the pancake coil of the second layer and the end of winding of the pancake coil of the first layer are connected to each other via a crossover portion which is passed in the axial direction. The superconducting wire is wound around the outer diameter side and is wound around the inner diameter side, and the winding start of the odd-numbered pancake coil and the winding end of the previous layer of the pancake coil are respectively passed in the axial direction. The superconducting wire of the even-numbered pancake coil is wound to the outer diameter side starting from the inner diameter side, and the winding of the even-numbered pancake coil is started, and In the superconducting coil, which is connected to the winding end of the coil via a bridging portion passed in the axial direction, the superconducting wires are connected to each other at the bridging portion so that the self and mutual inductance of the superconducting wires are uniform. It may be as dislocations change the order is made to overlap in the radial direction. Thereby, the self and mutual inductance of each superconducting wire are made uniform, and the sharing of the current flowing through each superconducting wire connected in parallel becomes uniform.

Further, in this configuration, a superconducting coil is formed from a pancake coil group in which the number of superconducting wires overlapping in the radial direction is different from each other in the axial direction by the same number of layers as the number of parallel superconducting wires. It is good to comprise. Thereby, the mutual inductance between the superconducting wires is made more uniform, and the sharing of the current flowing in each superconducting wire connected in parallel becomes more uniform.

In this configuration, the number of stacked pancake coils may be an integral multiple of twice the number of parallel superconducting wires. Thereby, the mutual inductance between the superconducting wires is made more uniform, and the sharing of the current flowing in each superconducting wire connected in parallel becomes more uniform.
With this configuration, even when the number of superconducting wires in parallel is odd, both the start of the winding of the pancake coil of the first layer and the end of the winding of the pancake coil of the last layer are both superconducting. It will be located on the outer diameter side of the coil.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. FIG. 1 is a one-side sectional view showing a configuration of a superconducting coil according to an embodiment of the present invention. Three superconducting wires 1, 2, and 3 connected in parallel are superposed in the radial direction (the left-right direction in FIG. 1), and are pancake coils P1 wound in a disk shape with the left side in FIG. 1 as a central axis. , P2, P3, P4, P
5, P6 are laminated in the axial direction (vertical direction in FIG. 1) in six layers. The superconducting wire 1 of the first pancake coil P1
The superconducting wires 2, 3 are wound from the terminal U for external connection of the superconducting coil to the inner diameter side, starting from the outer diameter side, and the superconducting wires 1, 2, 3 of the second-layer pancake coil P2 are wound on the inner diameter side. It is wound to the outer diameter side as the winding start. The start of the winding of the pancake coil P2 of the second layer and the end of the winding of the pancake coil P1 of the first layer are connected via a crossover portion T1 extending in the axial direction. Hereinafter, the superconducting wires 1, 2, and 3 of the odd-numbered pancake coils P3 and P5 are wound on the outer diameter side and then on the inner diameter side, and the odd-numbered pancake coils P3 and P5 start winding. The winding ends of the pancake coils P2 and P4 of the front layer are connected to each other via a crossover portion T2 which extends in the axial direction. Also, the superconducting wires 1, 2 and 2 of the pancake coils P4 and P6 of the even-numbered layers
No. 3 is wound to the outside diameter side starting from the inside diameter side, and the winding start of the even-numbered pancake coils P4 and P6 and the winding end of the pancake coils P3 and P5 of the previous layer are respectively passed in the axial direction. The connection is made via the connected transition section T1.
The end of the winding of the pancake coil P6 of the sixth layer is connected to another terminal u for external connection of the superconducting coil.

The transition portions T1 and T2 in FIG. 1 displace the superconducting wires 1, 2, and 3 at the ends of the pancake coils, respectively.
The superconducting wires 1, 2, 3 are formed such that the order of overlapping in the radial direction changes. That is, in the pancake coils P1, P2, and P3, the order in which the superconducting wires 1, 2, and 3 overlap in the radial direction is different from each other. Superconducting wires 1, 2, 3
When a pancake coil group in which radially overlapping pancake coils are sequentially stacked is regarded as one pancake coil group, the pancake coils P1, P2, and P3 form one pancake coil group G1, and the pancake coil group is formed. P4, P
5, P6 form another pancake coil group G2. However, the pancake coil groups G1 and G2 are
They have the same configuration.

In the pancake coil group G1 of FIG.
The winding radius of the superconducting wire 3 is largest in the pancake coil P1, but is smallest in the pancake coil P2, and is intermediate between the other superconducting wires 1 and 2 in the pancake coil P3. The winding radius of superconducting wire 2 is intermediate between other superconducting wires 1 and 2 in pancake coil P1, but is largest in pancake coil P2 and smallest in pancake coil P3. Further, the winding radius of the superconducting wire 1 is the smallest in the pancake coil P1, but is intermediate between the other superconducting wires 1 and 2 in the pancake coil P2, and is largest in the pancake coil P3. Therefore, in the pancake coil group G1, the average winding radius is
2 and 3, and the relative positional relationship between the superconducting wires becomes equivalent for the superconducting wires 1, 2, and 3, so that the self-conductivity and the mutual inductance of the superconducting wires 1, 2, and 3 are made uniform. Thus, the sharing of the current flowing through each superconducting wire 1, 2, 3 becomes uniform. The same applies to the pancake coil group G2. The self-conductivity and mutual inductance of the superconducting wires 1, 2, 3 in the pancake coil group G2 are made uniform, and the current flowing through each superconducting wire 1, 2, 3, is shared. Becomes uniform. Therefore, the sharing of the current flowing through the superconducting wires 1, 2, and 3 becomes uniform in the entire superconducting coil, the circulating current does not flow in the superconducting coil, and the AC loss accompanying the drift can be reduced. Further, the transition from the superconducting state to the normal conducting state becomes difficult when the critical current value is exceeded, and the excitation and demagnetization can be performed stably at high speed.

When the shunt ratio of the current flowing through each of the superconducting wires 1, 2, and 3 is calculated for the superconducting coil shown in FIG.
Thus, it was proved that the current almost uniformly shared and flowed. In general, the number N of stacked pancake coils in the superconducting coil is preferably set to an integral multiple of twice the number n of parallel superconducting wires. The number n of superconducting wires in the superconducting coil shown in FIG. 1 is three in parallel, and the number N of stacked pancake coils is six, which is an integral number that is twice as large as n = 3. For that, when the pancake coil P1 starts winding,
Since the end of the winding of the pancake coil P6 is both on the outer diameter side of the superconducting coil, the terminals U and u of the superconducting coil can be pulled out therefrom. This simplifies the configuration of the lead (not shown) from the terminals U and u. In the case of FIG. 1, the number N of stacked pancake coils
To 3 and only the pancake coil group G1
The self and mutual inductances of the superconducting wires 1, 2, 3 can be made uniform. However, in this case, it is necessary to pull out the lead out of the terminal from the inner diameter side of the pancake coil P3, so that the configuration of the lead out becomes very complicated. Therefore, in general, if the number of stacked pancake coils N in the superconducting coil is set to an integral multiple of twice the number of parallel superconducting wires n, the number of parallel superconducting wires n
Is odd, the beginning of the winding of the pancake coil of the first layer and the end of the winding of the pancake coil of the Nth layer, which is the last layer, both come to the outer diameter side of the superconducting coil, and the drawing is performed. The lead can be easily pulled out. Further, with such a configuration, the mutual inductance between the superconducting wires is made more uniform, and the sharing of the current flowing through the superconducting wires connected in parallel becomes more uniform.

FIG. 1 shows that the number of parallel superconducting wires n is three.
In the case of the superconducting wires, the above is the same regardless of whether the number of parallel superconducting wires n is four or five. When the number n of superconducting wires in parallel is four, the number N of pancake coils to be stacked may be 8 or 16. When the number n of superconducting wires is 5 in parallel, the number of stacked pancake coils N
May be set to 10 or 20. The number of parallel superconducting wires n is 3
In the case of a book, it goes without saying that the number of laminations N of the pancake coils may be 12 or 24 in addition to the embodiment of FIG.

In the above embodiment, the superconducting wire of the pancake coil of the first layer in the superconducting coil has been described as being wound around the outer diameter side and then toward the inner diameter side. The superconducting wire of the pancake coil may be wound around the inner diameter side and then wound on the outer diameter side, and the first layer of the superconducting coil and the N layer which is the last layer of the pancake coil may be wound. The end of the pancake coil of the eye may be located on the inner diameter side of the superconducting coil.

Further, in the above-described embodiment, the configuration in which the number of stacked pancake coils in each pancake coil group constituting the superconducting coil is the same as the number of parallel superconducting wires has been described. However, the present invention is not limited to the above configuration. That is, a configuration in which the number of stacked pancake coils in each pancake coil group is different from the number of parallel superconducting wires, for example, a configuration in which the number of laminations is larger than the number of parallel superconducting wires, or the number of stacked pancake coils in the entire superconducting coil is superconducting The configuration may be different from an integral multiple of the number of parallel wires, and the transposition at the transition between layers is performed so that the self-conductivity and mutual inductance of each superconducting wire connected in parallel are uniform over the entire superconducting coil. You can make it happen.

Further, in the superconducting coil of the embodiment shown in FIG. 1, as described above, each superconducting wire 1, 1 connected in parallel is connected.
A few self and mutual inductances are equalized for each of the pancake coil groups G1 and G2. In such a configuration in which the self and mutual inductance of each superconducting wire connected in parallel are equalized for each pancake coil group,
When constructing the entire superconducting coil, simply by stacking the pancake coil groups, the self-conducting and mutual inductance of each superconducting wire connected in parallel is easily made uniform in the entire superconducting coil. be able to.

In the case where a superconducting coil is formed by laminating a plurality of the pancake coil groups, it is easier to make the symmetry in the axial direction of the entire superconducting coil easier if the number of the laminated groups is even. Can be realized.

In the superconducting coil of the embodiment shown in FIG. 1, the pancake coils P1, P2, P
3, P4, P5, and P6 have the same number of turns. In such a superconducting coil in which the number of turns of each laminated pancake coil is the same, the outer diameter of all pancake coils is the same as the maximum outer diameter of the superconducting coil.
On the other hand, in a superconducting coil having a configuration in which pancake coils having different numbers of turns are stacked, the maximum outer diameter of the superconducting coil is determined by the outer diameter of the pancake coil having the largest number of turns. Therefore, when the maximum outer diameter of the superconducting coil is the same, a configuration in which the number of turns of each of the laminated pancake coils is the same as the superconducting coil of the embodiment shown in FIG. As the number of turns can be increased, the current required to form a magnetic field of the same magnitude can be reduced as compared to a configuration in which pancake coils with different numbers of turns are stacked. .

Further, the superconducting coil of the embodiment shown in FIG. 1 has a configuration in which pancake coils of different winding numbers are stacked because the number of turns of each pancake coil is the same. As compared with the above, the production of the superconducting coil, that is, the operation of stacking a plurality of pancake coils and connecting the pancake coils becomes easier.

[0022]

According to the present invention, as described above, the transposition is performed by changing the order in which the superconducting wires are superposed in the radial direction at the bridging portion so that the self and mutual inductance of each superconducting wire are uniform. The distribution of the current flowing through each superconducting wire becomes uniform, the AC loss is reduced, and the transition from the superconducting state to the normal conducting state beyond the critical current becomes difficult, and stable high-speed excitation and demagnetization can be performed. become able to.

Further, in this configuration, a superconducting coil is formed from a pancake coil group in which pancake coils of superconducting wires which are different from each other in the radial direction and are stacked in the axial direction by the same number of layers as the number of parallel superconducting wires. With this configuration, the sharing of the current flowing through each superconducting wire becomes more uniform.

In this configuration, the number of stacked pancake coils is set to be an integral multiple of twice the number of superconducting wires in parallel, so that the current flowing through each superconducting wire becomes more uniform, and the superconducting wires become more uniform. Even when the number of parallel wires is an odd number, the configuration of the lead out from the terminal of the superconducting coil can be simplified.

[Brief description of the drawings]

FIG. 1 is a one-side sectional view showing a configuration of a superconducting coil according to an embodiment of the present invention.

FIG. 2 is a half sectional view showing the configuration of a conventional superconducting coil.

[Explanation of symbols]

1,2,3: superconducting wire, P1, P2, P3, P4, P
5, P6: Pancake coil, T1, T2: Crossover, G
1, G2: Pancake coil group, U, u: Terminal, N: Number of stacked pancake coils, n: Number of parallel superconducting wires

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuo Funaki 1-7-1 Midorigaoka, Higashi-ku, Fukuoka City, Fukuoka Prefecture (72) Inventor Narita, Iwama 26-402 Shimo-Dari Danchi, Onojo-shi, Fukuoka Prefecture (72) Inventor Akira Tomioka Fuji Electric Co., Ltd. (1-1) Tanabe Nitta, Kawasaki-ku, Kawasaki, Kanagawa Prefecture (72) Inventor Takaaki Bono 1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Fuji Electric Co., Ltd. (72) Inventor Konno Masayuki Fuji Electric Co., Ltd. 1-1 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa

Claims (3)

[Claims] 1. A pancake coil in which a plurality of superconducting wires connected in parallel are superposed in the radial direction and wound in the shape of a disc are laminated in a plurality of layers in the axial direction. The superconducting wire is wound to the inside diameter side starting from the outside diameter side, and the superconducting wire of the second layer pancake coil is wound to the outside diameter side starting from the inside diameter side, and The start of winding of the pancake coil and the end of winding of the first pancake coil are connected to each other via a crossover portion extending in the axial direction. Wound to the inner diameter side starting from the radial side, and starting to wind the odd-numbered pancake coil,
The end of the pancake coil of the previous layer is connected to the end of the pancake coil via a crossover that is passed in the axial direction, and the superconducting wire of the even-numbered pancake coil is wound to the outside diameter side starting from the inside diameter side. In the superconducting coil, the start of winding of the even-numbered pancake coil and the end of winding of the pancake coil of the preceding layer are connected via a crossover portion passed in the axial direction, respectively. A superconducting coil, wherein transposition is performed at the transition portion to change the order in which superconducting wires are superposed in the radial direction so that self and mutual inductances are uniform. 2. The superconducting coil according to claim 1,
A superconducting coil comprising a pancake coil group in which pancake coils having different superconducting wires overlapping in the radial direction are stacked in the axial direction by the same number of layers as the number of parallel superconducting wires. 3. The superconducting coil according to claim 1,
A superconducting coil, wherein the number of the stacked pancake coils is an integral multiple of twice the number of parallel superconducting wires.