End structure for superconducting cable and connection terminal

Abstract

To suppress reduction of an electrification performance (current value) in an end structure for a superconducting cable.SOLUTION: An end structure for a superconducting cable comprises at least a multilayer conductor 10 and an electrode part 30, and the multilayer conductor 10 is configured by laminating a plurality of superconducting wires 20, each presenting a tape shape, in a thickness direction of the superconducting wire 20. The electrode part 30 includes at least a plurality of slits 40. The multilayer conductor 10 is divided into a plurality of wire units 11, and stored in the slit 40 for each wire unit 11. When storing two superconducting wires 20 in the slit 40, it is preferable that directions of faces of the superconducting wires 20 are adjusted in such a manner that faces at the sides of a superconducting layer 23 and a stabilizing layer 24 constituting the superconducting wire 20 is brought into contact with or made close to an inner wall surface of the slit 40.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an end structure and a connection terminal for a superconducting cable. [Background technology]

[0002] A method has been developed that uses a laminated conductor made by stacking multiple tape-shaped superconducting wires, as described in Patent Document 1, etc., as a superconducting cable for transmitting electricity to equipment that utilizes superconductivity (hereinafter simply referred to as "superconducting equipment"). This method makes it possible to reduce the weight of superconducting cables compared to conventional superconducting cables such as three-phase coaxial or three-core in one type, and is therefore expected to be useful in superconducting cables for aircraft, which have strict weight restrictions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-125436 A Summary of the Invention [Problem to be solved by the invention]

[0004] When connecting a superconducting cable using a laminated conductor to superconducting equipment, it is necessary to connect the end of the laminated conductor to an electrode portion provided within a connection terminal having a shape corresponding to the connection to the superconducting equipment. However, when a laminated conductor is directly connected to the electrode part in a connection terminal, there was a problem that the actual measured electrical performance (current value) was lower than the designed electrical performance (current value) determined by the product of the electrical performance of the superconducting wire alone and the number of layers. This is thought to be because the superconducting layer of the superconducting wire located toward the center in the stacking direction of the laminated conductor is separated from the electrode portion, making it difficult to secure the current path (connection cross-sectional area), resulting in electrical imbalance.

[0005] Therefore, an object of the present invention is to provide a means capable of suppressing a decrease in current-carrying performance in an end structure of a superconducting cable. [Means for solving the problem]

[0006] In order to solve the above problems, in the present invention, the end structure of a superconducting cable has at least a laminated conductor and an electrode portion, the laminated conductor being formed by stacking multiple tape-shaped superconducting wires in the thickness direction of the superconducting wires, the electrode portion having at least a plurality of slits, and the multiple superconducting wires constituting the laminated conductor are divided into a plurality of wire units and each wire unit is accommodated in the slit. With this configuration, it is possible to ensure a current path (connection cross-sectional area) for each superconducting wire, and to suppress the occurrence of electrical imbalance, compared to when the laminated conductor is directly connected to the electrode portion. Effect of the Invention

[0007] According to the present invention, it is possible to suppress the deterioration of current-carrying performance in the end structure of a superconducting cable. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing an example of an end structure of a superconducting cable according to the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing an example of the configuration of a superconducting wire. [Diagram 3] FIG. 4 is a schematic diagram showing a configuration example of an electrode unit. [Figure 4] FIG. 4 is a schematic diagram showing an example of accommodating a superconducting wire in a slit. [Diagram 5] FIG. 1 is a schematic diagram showing a storage example according to Experimental Example 1. [Figure 6] FIG. 11 is a schematic diagram showing a storage example according to Experimental Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. EXAMPLES

[0010] <1> Overall configuration (Fig. 1) The end structure of a superconducting cable according to the present invention (hereinafter also referred to as "this structure") is a structure that can be applied to a superconducting cable for connecting between a power source and superconducting equipment or between superconducting equipment. In the present invention, the term "superconducting cable" is not limited to a configuration in which a conductor is provided with a shield and / or an insulator, but also includes a configuration consisting of only a conductor. In the example shown in FIG. 1, the components of the present invention include at least a laminated conductor 10 constituting a superconducting cable, and an electrode portion 30 constituting a part or all of a connection terminal for connecting the superconducting cable to a power source, a superconducting device, or the like. Each component will be described in detail below.

[0011] <2> Laminated conductor (Figure 1) The laminated conductor 10 is a component that is disposed inside a superconducting cable to transmit electricity in a superconducting state. The laminated conductor 10 is a member formed by laminating a plurality of superconducting wires 20 in the thickness direction of the superconducting wires 20 . In the present invention, the number of superconducting wires 20 constituting the laminated conductor 10 is not particularly limited. In the example shown in FIG. 1, the laminated conductor 10 is composed of four superconducting wires 20 . When the laminated conductor 10 is connected to the electrode portion 30 described later, the laminated conductor 10 is connected to a plurality of wire units 11 each obtained by dividing the plurality of superconducting wires 20 constituting the laminated conductor 10 into smaller pieces. The number of superconducting wires 20 constituting the wire unit 11 can be appropriately set within a range excluding the total number of superconducting wires 20 constituting the laminated conductor 10 .

[0012] <3> Superconducting wire (Fig. 1, Fig. 2) The superconducting wire 20 is a tape-shaped conductive member that constitutes the laminated conductor 10 . In the present invention, the type of superconducting wire 20 is not particularly limited. In this embodiment, a tape-shaped MOD (Metal Organic Deposition Processes) type wire is used as the superconducting wire 20 . Superconducting wire 20 shown in FIG. 2 has, in the thickness direction, from the bottom to the top of the page, substrate 21, intermediate layer 22, superconducting layer 23, and stabilizing layer 24. Each part will be described in detail below.

[0013] <3.1> Substrate (Fig. 2) Substrate 21 is a portion that serves as a base for superconducting wire 20 . In the present invention, the type of substrate 21 is not particularly limited, but for example, an alloy of nickel (Ni) or copper (Cu) to which one or more elements selected from tungsten (W), tin (Sn), zinc (Zn), molybdenum (Mo), chromium (Cr), vanadium (V), tantalum (Ta), or titanium (Ti) have been added can be used.

[0014] <3.2> Middle layer (Fig. 2) Intermediate layer 22 is provided between substrate 21 and superconducting layer 23 to prevent reaction between substrate 21 and superconducting layer 23 during heat treatment when superconducting wire 20 is produced. In the present invention, the type and number of layers of the intermediate layer 22 are not particularly limited. For example, ceria (CeO 2 ) or manganese oxide (MgO), etc. can be used.

[0015] <3.3> Superconducting layer (Fig. 2) The superconducting layer 23 is a portion for passing current in a superconducting state. In the present invention, the type of superconducting layer 23 is not particularly limited, but for example, an yttrium-based oxide superconductor (RE123) or the like can be used. The superconducting layer 23 can be formed by, for example, MOD (Metal Organic Deposition Processes: organic acid salt deposition processes).

[0016] <3.4> Stabilization layer (Fig. 2) The stabilization layer 24 is formed directly on the superconducting layer 23 to stabilize the superconducting layer. More specifically, the stabilization layer 24 is a member for diverting electric current and dispersing heat generated by fault current or AC current flow to prevent breakdown and performance degradation due to heat generation. In the present invention, the type of stabilization layer 24 is not particularly limited, but in particular, noble metals such as silver (Ag), gold (Au), platinum (Pt), etc., or alloys thereof can be used, and it is particularly preferable to use a metal with low resistance.

[0017] <4> Electrode section (Fig. 1) The electrode portion 30 is a member for connecting the end of a connection terminal. Electric power transmitted from the laminated conductor 10 can be supplied to a superconducting device to which a connection terminal is connected via the electrode portion 30 according to the present invention. In the present invention, the material of the electrode portion 30 is not particularly limited, but it is particularly preferable to use a material with excellent electrical conductivity, such as copper (Cu).

[0018] <5> Slit (Fig. 1, Fig. 3) Slit 40 is a portion for accommodating an end of superconducting wire 20 . The slit 40 is a groove formed so as to communicate with one end side of the electrode portion 30 . A plurality of slits 40 are provided at intervals in the width direction of slit 40 (thickness direction of superconducting wire 20 to be accommodated). Then, the superconducting wires 20 constituting the laminated conductor 10 are accommodated in the respective slits 40, and the superconducting wires 20 are fixed to the electrode portions 30 by using a suitable joining method such as soldering. By accommodating each superconducting wire 20 constituting the laminated conductor 10 in the slit 40 in this manner, the surface (one surface 20a) of each superconducting wire 20 facing the superconducting layer 23 and the stabilization layer 24 is positioned so as to be in contact with or close to the electrode portion 30, thereby ensuring the current path (connection cross-sectional area) of each superconducting wire 20 and suppressing the occurrence of electrical imbalance.

[0019] <5.1> Slit width (Fig. 3) In the present invention, the width B of the slit 40 is set to a length sufficient to accommodate a wire unit 11 consisting of at least one superconducting wire 20 in the thickness direction of the superconducting wire 20. Furthermore, the widths B of the slits 40 may be equal or different.

[0020] <5.2> Slit length (Fig. 3) In the present invention, the storage length L1 of the slit 40 is not particularly limited. Moreover, the storage lengths L1 of the slits 40 may be the same or different.

[0021] <5.3> Distance between slits (Fig. 3) In the present invention, the separation length L2 between the slits 40 is not particularly limited, and may be appropriately determined depending on the width of the electrode portion 30, the width of the slits 40, the number of slits 40, and the like. Furthermore, the separation lengths L2 of the slits 40 may be equal or different.

[0022] <5.4> When two or more superconducting wires are accommodated in a slit (Fig. 4) In the present invention, when a wire unit 11 consisting of two or more superconducting wires 20 is accommodated in one slit 40, it is preferable that the two superconducting wires 20 located on both sides of the wire unit 11 have their two surfaces in the thickness direction of each superconducting wire 20, that is, the surface (one surface 20a) facing the superconducting layer 23 and the stabilizing layer 25, facing the inner wall side of the slit 40, i.e., the side closer to the electrode portion 30, and the surfaces (the other surfaces 20b) facing the substrate 20, facing each other, that is, the two superconducting wires 20 are configured with their orientations in the thickness direction swapped. In Figure 4, wire unit 11 consisting of two superconducting wires 20 is configured by swapping the orientation of each superconducting wire 20 in the thickness direction so that one surface 20a of each superconducting wire 20 faces the side closer to electrode portion 30.

[0023] With this configuration, the deterioration of the total electrical conductivity performance can be further suppressed compared to when multiple superconducting wires 20 are stored in the same orientation or when the surfaces (one surface 20a) facing the superconducting layer 23 and the stabilizing layer 25 are arranged opposite each other.

[0024] The number of superconducting wires 20 constituting the wire unit 11 housed in the slit 40 may be appropriately set within a range that satisfies the current-carrying performance required for the superconducting cable as a whole and the size required for the electrode portion 30 . For example, if the required electrical conductivity is not satisfied simply by connecting the laminated conductor 10 to the electrode portion 30 as is, the superconducting wire of the laminated conductor can be appropriately divided into smaller portions and accommodated in the slits of the electrode portion 30 so as to satisfy this electrical conductivity. Furthermore, when multiple superconducting wires are accommodated in each slit 40, the width of the slit increases compared to accommodating one superconducting wire in each slit, but the number of slits can be reduced, creating room for making the electrode section 30 smaller while still suppressing some degree of degradation in electrical conductivity performance.

[0025] <5.5> Differences in the number of accommodating units in the slit (not shown) The present invention may be configured such that in one electrode portion 30, each slit 40 accommodates a different number of superconducting wires 20, for example, a slit 40 that accommodates one superconducting wire 20 and a slit 40 that accommodates two superconducting wires 20 may be mixed. This configuration can be applied, for example, to a case where the laminated conductor 10 is composed of an odd number of superconducting wires 20.

[0026] <6> Comparative test [1] (Tables 1 to 3, Figures 5 and 6) A comparative test was carried out on the current carrying performance (current value) between electrodes provided at both ends of a superconducting cable in which a laminated conductor 10 made of eight superconducting wires 20 was arranged. In this test, the layouts shown in the figures were applied to both ends of the superconducting cable.

[0027] <6.1> Materials used (Table 1, Table 2) Details of each material used are shown in Tables 1 and 2.

[0028] [Table 1] TIFF2025083768000002.tif40151

[0029] [Table 2] TIFF2025083768000003.tif45151

[0030] <6.2> Layout examples (Fig. 5, Fig. 6) Regarding the end structure of the superconducting cable, the layout of the slits 40 and the superconducting wires 20 was set to the following two types.

[0031] (1) Experimental Example 1 (Figure 5) A laminated conductor 10 consisting of eight superconducting wires 20 was housed in one slit 40 provided in the electrode section 30. The eight superconducting wires 20 constituting the laminated conductor 10 were arranged such that, in each wire unit 11 consisting of four adjacent wires, the surface of each superconducting wire 20 on the substrate 21 side (the other surface 20b) faces the inside of the laminated conductor 10, and the surface (the one surface 20a) on the superconducting layer 23 and stabilizing layer 24 (not shown in FIG. 5) side faces the inner wall of the slit 40.

[0032] (2) Experimental Example 2 (Figure 6) Wire units 11 each consisting of two superconducting wires 20 were housed in four slits 40 provided in the electrode section 30. The two superconducting wires 20 housed in the same slit 40 were arranged such that the surface (one surface 20a) on the superconducting layer 23 and stabilizing layer 24 side faced the inner wall of the slit 40.

[0033] <6.3> Test results (Table 6) Table 3 shows the actually measured current values ​​and the ratios to the design current values ​​in Experimental Examples 1 and 2. [Table 3] TIFF2025083768000004.tif33151As shown in Table 3, it was found that by dividing the superconducting wire into small portions and accommodating them in the slits 40 formed in the electrode portion 30, the actual measured current value approaches the design current value, and the deterioration of the electrical conductivity is suppressed. In this comparative test, no experiment was conducted on a configuration in which superconducting wires 20 are housed one by one in slits 40. However, in the case of this configuration, it is clear that the surface of each superconducting wire 20 facing stabilization layer 24 always faces the inner wall of slit 40, and therefore it is considered possible to ensure an actual current value at least equal to or greater than that of experimental example 2. [Explanation of symbols]

[0034] 10: Laminated conductor 11: Wire unit 20: Superconducting wire 21: Substrate 22: Middle class 23: Superconducting layer 24: Stabilization layer 30: Electrode part 40: Slit B: Slit width L1: Slit storage length L2: Distance between slits

Claims

1. An end structure of a superconducting cable, comprising: at least a laminated conductor and an electrode portion; wherein the laminated conductor is formed by laminating a plurality of tape-shaped superconducting wire materials in the thickness direction of the superconducting wire materials; the electrode portion has at least a plurality of slits; a plurality of the superconducting wire materials constituting the laminated conductor are divided into a plurality of wire units, and each wire unit is accommodated in the slit, characterized in that it is an end structure of a superconducting cable.

2. The end structure of a superconducting cable according to Claim 1, wherein the wire unit is composed of one or two of the superconducting wire materials.

3. The superconducting wire material has at least a substrate, an intermediate layer, a superconducting layer, and a stabilizing layer in the tape thickness direction; when at least two of the plurality of superconducting wire materials are accommodated in at least one of the plurality of slits, the surface on the stabilizing layer side of the two surfaces of each superconducting wire material in the tape thickness direction faces the inner wall side of the slit, characterized in that it is an end structure of a superconducting cable according to Claim 1 or 2.

4. A connection terminal for a superconducting cable, comprising an electrode portion for connecting an end of a superconducting cable including a laminated conductor formed by laminating a plurality of tape-shaped superconducting wire materials, wherein the electrode portion is provided with a plurality of slits capable of accommodating a plurality of wire units obtained by dividing a plurality of the superconducting wire materials constituting the laminated conductor, characterized in that it is a connection terminal for a superconducting cable.

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