JP2005333040A - Superconducting coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superconducting coil excellent in superconductivity by solving various problems generated in the superconducting coil using a transposed conductor, wire winding equipment making such a superconducting coil, an electrode for the transposed conductor, and the transposed conductor or the like. <P>SOLUTION: The superconducting coil is constituted by winding the transposed conductor formed by heaping high temperature superconductive strands preparing a smooth layer on periphery. A bending strain applied to the transposed conductor when winding and after winding the superconducting coil is 1% or less. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a superconducting coil for a large superconducting magnet used in a superconducting power storage device, a nuclear fusion reactor or the like.

  High-temperature superconductors are used for coil applications such as superconducting coils for superconducting power storage (SMES) devices and superconducting coils for superconducting transformers, and have high critical temperatures, low operating costs, Thermal stability is superior to conventional metal-based low-temperature superconductors. For example, bismuth-based and yttrium-based oxide high-temperature superconductors have been developed.

  However, superconducting wires using these high-temperature superconducting conductors have a low critical current density compared to superconducting wires using metal-based low-temperature superconducting conductors, which hinders practical application.

  Therefore, as a means for increasing the conductor current capacity, a method of transposing a plurality of superconducting wires to form a single conductor has been developed and used for superconducting power cables and the like (for example, see Patent Documents 1 and 2). .

  In this dislocation conductor, the current between the strands is equalized with respect to alternating current or pulsed current, so that the capacity can be increased and the alternating current loss can be suppressed as compared to other conductive structures. It is characterized by being excellent. In other words, when the energization current flows with the current flowing between the strands, the electromagnetic force balance between the strands and the loss can be suppressed or reduced as compared with the case where the current does not flow.

JP-A-9-120922 JP 2002-110434 A

  However, several problems have arisen when producing superconducting coils using dislocation conductors.

  The first problem is that when a superconducting coil is produced by winding a dislocation conductor, the conductor characteristics (superconducting characteristics) are significantly reduced, and it is expected that a plurality of superconductor strands are bundled into a dislocation conductor. It is a problem that the effect of increasing the current capacity cannot be obtained.

  One reason for this is that slippage between superconductor strands (hereinafter abbreviated as strands) constituting the dislocation conductor is poor during the production of the superconducting coil, and some of the strands are caught, resulting in deterioration of characteristics. It is conceivable that moderate strain is applied.

  Another reason is considered to be bending strain applied to the dislocation conductor in the winding device used during the winding work for producing the superconducting coil from the dislocation conductor.

  That is, when the winding operation is temporarily stopped or unwound, a part of the dislocation conductor hangs down between the unwinding device and the winding device, and a bending strain is applied to the dislocation conductor.

  Furthermore, when the dislocation conductor drawn from the unwinding device passes through a winding line composed of a winding device member such as a tension control device, an excessive bending strain is applied when reversal of the bending direction occurs, This is a case where the characteristics of the dislocation conductor are significantly deteriorated. In actual winding work of superconducting coils, it seems that the conductor characteristics deteriorate due to the influence of both.

  For example, a description will be given with reference to FIG. The winding device 20 includes a winding device 25 having a winding device 21, a tension detection reel 22, a direction changing reel 23, and a bobbin 24 having a winding inner diameter of 120 mm. In the winding device 20, the dislocation conductor 1 is wound in the direction of the arrow, and the bending direction is reversed during traveling between the tension detection reel 22 and the direction conversion reel 23.

  A winding conductor 20 is used to wind the dislocation conductor 1, and a copper plate electrode is soldered to the end of the dislocation conductor 1 to produce a superconducting coil, and then an energization test is performed using the superconducting coil. went. As a result, the critical current decreased by 50% compared to immediately after dislocation conductor formation, and the performance required for a superconducting coil could not be obtained.

  Further, when a magnetic field of 1 T (hereinafter, T represents Tesla) was applied to the superconducting coil and energized at a liquid helium temperature, the critical current was reached with a 56 MPa hoop electromagnetic force. However, this value was almost half of the hoop electromagnetic force 100 MPa assumed for normal equipment products. Therefore, the above problem has hindered commercialization with oxide superconductors.

  The second problem is that, after winding and forming a superconducting coil, when the electrode parts forming the energization electrode and the end of the dislocation conductor are connected by soldering, the superconductor strand of the dislocation conductor is energized. In other words, the characteristics are deteriorated due to the fact that the current is not smoothed between the electrodes, or the distortion is applied to the strands of the dislocation conductor in the vicinity of the electrodes due to the electromagnetic force generated by energization.

  The cause of this is as follows. It is necessary to provide an electrode for energization at the end of the dislocation conductor. However, because the dislocation conductor is a bundle of multiple superconductor wires, when the end of the dislocation conductor is simply soldered to a metal plate and connected, current distribution by dislocation is caused by variation in connection resistance. May be hindered.

  Furthermore, it is considered that local distortion is applied to the conductor in the vicinity of the electrode due to electromagnetic force during soldering work or energization, causing deterioration of the characteristics of the dislocation conductor.

  As a third problem, a binding part is necessary to maintain the shape of the dislocation conductor, and local strain is applied to the dislocation conductors above and below the dislocation conductor winding coil where the binding part is located. And the deterioration of the characteristics of the dislocation conductor occurs.

  Therefore, in the present invention, various problems that occur in superconducting coils using dislocation conductors are solved, and a superconducting coil that exhibits excellent superconducting characteristics, a winding device that provides such superconducting coils, electrodes for dislocation conductors, dislocations Provide conductors and the like.

In order to solve the above problems, a first aspect of the present invention is a superconducting coil configured by winding a dislocation conductor formed by stacking high-temperature superconductor wires each having a smooth layer on the outer periphery,
The superconducting coil is characterized in that a bending strain applied to the dislocation conductor during and after winding of the superconducting coil is 1% or less.

  A second aspect of the present invention is the superconducting coil, wherein the smooth layer is composed of any one of a resin material layer and a metal material layer, or one or more layers.

  A third aspect of the present invention is a superconducting coil, characterized in that a spacer is provided between the dislocation conductors and the dislocation conductors that overlap each other in the superconducting coil.

A fourth aspect of the present invention is a superconducting coil in which the thickness of the transition conductor is t (mm), and the winding inner diameter of a coil formed by winding the dislocation conductor is D (mm),
The superconducting coil is characterized in that the thickness t (mm) of the dislocation conductor and the winding inner diameter D (mm) of the superconducting coil satisfy the following relationship.
0 <t ≦ D / 100

  In the fifth aspect of the present invention, winding is performed so that the bending applied to the dislocation conductor forming the superconducting coil is bending in the same direction and the bending strain is 1% or less. This is a method for manufacturing a superconducting coil.

According to a sixth aspect of the present invention, in the winding device including the unwinding device, the winding device, and at least one winding device component between them,
The unwinding device, the winding device, and the winding device components are arranged so that the bending strain applied to the dislocation conductor is 1% or less between the unwinding device and the winding device. Is a winding device.

According to a seventh aspect of the present invention, in the winding device including the unwinding device, the winding device, and at least one winding device component between them,
The winding device is characterized in that an unwinding device, a winding device, and a winding device component are arranged so that the dislocation conductor is bent in the same direction.

According to an eighth aspect of the present invention, there is provided a winding device including a winding device, a winding device, and at least one winding device component between them.
Between the unwinding device and the winding device, the unwinding device, the winding device, and the winding device components are arranged so that the bending strain applied to the dislocation conductor is 1% or less,
The winding device is characterized in that the unwinding device, the winding device, and the winding device components are arranged so that the dislocation conductor is bent in the same direction.

  According to a ninth aspect of the present invention, there is provided a winding device including a winding device, a winding device, and at least one winding device component therebetween, and the dislocation conductor in which the winding device component is running. A winding device characterized in that it is a component that suppresses sagging.

  According to a tenth aspect of the present invention, there is provided a superconducting coil electrode including a step for connecting a dislocation conductor provided in accordance with a thickness of each high-temperature superconductor element of a dislocation conductor formed by stacking high-temperature superconductor elements. It is.

  An eleventh aspect of the present invention is a superconducting coil comprising a superconducting coil electrode at an end of the superconducting coil.

  The present invention makes it possible to produce superconducting coils with excellent characteristics composed of dislocation conductors using high-temperature oxide superconductors, and to develop and manufacture superconducting power storage devices, superconducting transformers, and AC coils. Is possible. Therefore, there is an industrially remarkable effect.

  First, in the superconducting coil, the bending strain in the longitudinal direction is set to 1% or less. In order to make it 1% or less, it is necessary to smooth the surface of the superconductor wire (hereinafter abbreviated as “wire”) constituting the dislocation conductor and smooth the slip between the wires. Examples of the smoothing method include a method of coating a resin or the like, or attaching a metal material having a smooth flat surface such as stainless steel to an element wire.

  A method for adjusting the winding inner diameter of the superconducting coil and the thickness of the conductor so that the bending strain applied to the dislocation conductor at the time of winding the coil is within 1% by using the formula relating to the bending strain shown in the following formula (1). There is.

As a result, the dislocation conductor wound by the coil winding frame can slip during the winding of the strands, avoiding local bending strain and bending strain applied to the dislocation conductor during coil winding. Can be suppressed to within 1%, and superconducting characteristics are not deteriorated.
ε = (t / D) × 100 (1)
Here, each symbol indicates the following.
ε (%): Bending strain t (mm): Dislocation conductor thickness D (mm): Inside diameter of coil

In the present invention, the thickness (t) of the dislocation conductor and the winding inner diameter (D) of the superconducting coil satisfy the relationship of the following formula.
0 <t ≦ D / 100 (2)
That is, in the present invention, the bending strain is set within 1%. Therefore, when formula (1) is modified, the following formula (3) is obtained.
ε = (t / D) × 100 ≦ 1 (3)
Further, when the formula (3) is modified, the following formula (4) is obtained.
t ≦ D / 100 (4)
The value of t is 0 (mm) or more. Therefore, the formula (2) is derived from the formula (4) in the present invention.

  In a winding device for producing a superconducting coil by winding a dislocation conductor, the travel line of the dislocation conductor reaches a coil winding frame through several feeds (hereinafter referred to as a reel) from the unwinding device. Turned to form a superconducting coil. In this travel line, the object of the present invention can be achieved by providing a dislocation conductor support made of a pipe, a plate or the like between the reels so as to support the dislocation conductor.

  In other words, when the winding work is interrupted by passing through the installed pipe, sliding on the plate, or running just above the plate, the dislocation conductor can be used for rewinding. Even in the case where slack occurs, the bending strain generated in the dislocation conductor by the dislocation conductor support can be kept within 1%, thereby preventing the deterioration of the dislocation conductor characteristics.

  Further, regarding the dislocation conductor, it is desirable to arrange the components of the winding device so that the bending direction becomes one direction like a swing swing after being fed out from the unwinding device onto the travel line. Then, the bending strain applied to the dislocation conductor is only in one direction, and the reversal of the bending direction such as repeated bending does not occur, so that deterioration of the dislocation conductor characteristics can be prevented.

  The electrode provided at the end of the dislocation conductor has a structure in which the number of steps is equal to the number of stacked dislocation conductors, and a step having a height corresponding to the thickness of the strand constituting the dislocation conductor is provided. Each layer of dislocation conductors is connected to the stepped portion by soldering.

  As a result, the connection resistance between the metal plate constituting the electrode and the dislocation conductor can be made to be substantially equal to each other, and the current can be leveled. In addition, it is possible to prevent local distortion during soldering and local distortion due to electromagnetic force, and it is possible to prevent deterioration of conductor characteristics due to energization.

  When the bundling portion for holding the shape of the dislocation conductor is provided, when the bundling portion is wound in a coil shape, local distortion is applied to the dislocation conductors in the upper and lower layers of the bundling portion. In order to prevent these local distortions, it is desirable to produce a dislocation conductor wound coil by providing a plate-like or film-like spacer between each layer.

  The present invention will be described in detail with reference to FIGS. 1 and 2, reference numeral 1 is a dislocation conductor, reference numeral 2 is a strand (superconductor), 3 is a smooth layer provided on the surface of the strand, 4a is a resin-coated strand, and 4b is a metal. It is a board sticking strand. As shown in FIG. 1, a bismuth-based high-temperature superconductor strand using a silver magnesium alloy sheath having a thickness of 0.2 mm and a width of 1.85 mm was used for the strand 2 constituting the transition conductor 1.

  As the smooth layer 3 provided on the surface of this strand, a formal insulating resin was provided at a coating thickness of about 20 μm to produce a resin-coated strand 4a. In addition to the formal, the coating may be coated with an epoxy resin, a polyimide tape, a mylar tape, or the like, or as shown in FIG. 1B, a metal with a smooth surface such as a stainless steel tape or a copper tape. Tapes may be attached or stacked.

  Next, this resin-coated strand was converted into a dislocation conductor. As shown in FIG. 2, first, six resin-coated strands 4a each having a length of 50 m were prepared, and they were converted to dislocation conductors while dislocation was performed at a dislocation pitch of 570 mm. The dislocation conductor had a thickness of 1.3 mm and a width of 4.0 mm. The dislocation conductor 1 had a critical current (Ic) at a liquid nitrogen temperature under a self-magnetic field of 156 A.

  This dislocation conductor was wound on a bobbin having a winding inner diameter of φ200 mm to produce a dislocation conductor supply coil.

  For production of the superconducting coil, for example, a glass fiber reinforced plastic bobbin 5 having a winding inner diameter of 200 mm and a winding width of 90 mm as shown in FIG. The winding inner diameter of the bobbin 5 is determined so that the strain applied to the dislocation conductor is within 1%, but a strain of about 0.3% is expected as a safety margin, and the bending strain of the dislocation conductor is 0.7. It calculated | required from said Formula (1) so that it might become about%. Therefore, when the bobbin winding inner diameter is D = 200 mm, the bending strain ε is set to 0.65%.

  The dislocation conductor was wound around the bobbin 5 with a solenoid winding. As shown in FIG. 3B, in the winding of the solenoid winding, every time one dislocation conductor is formed, an epoxy resin is applied to the outer periphery of the layer, and a width of 5 mm and a thickness of 0.4 mm are further formed thereon. The fiber-reinforced plastic spacer 6 was provided. The spacers 6 were arranged so as to be 24 evenly in the circumferential direction of the winding of the superconducting coil. A predetermined number of turns was formed by repeatedly winding a layer of the next dislocation conductor on the spacer 6.

  During winding, the strands forming the dislocation conductors slip smoothly from each other so that local bending strain does not occur in the strands. After the end of winding, electrodes were soldered to both ends of the dislocation conductor.

  FIG. 4 shows a winding apparatus for producing a superconducting coil by winding a dislocation conductor 1 around a bobbin. The superconducting coil bobbin 5 was attached to the winding device 8 of the winding device 7, the bobbin 5 was rotated, and the dislocation conductor 1 was wound up by the winding device 8 in the direction of the arrow to produce a superconducting coil 9.

  The dislocation conductor 1 is fed out from the dislocation conductor supply coil 11 installed in the unwinding device 10 and advances along the travel line of the winding device 7. In this travel line, there is a tension detection reel 12 having a diameter of 300 mm. The tension detection reel 12 is fed back to control the winding tension of the dislocation conductor 1.

  The dislocation conductor 1 that has passed through the tension detection reel 12 is wound around the bobbin 5, but the tension detection reel is such that the bending direction of the dislocation conductor 1 is always the same as the winding direction of the dislocation conductor supply coil 11. Winding device components such as 12 and bobbin 5 were arranged.

  Further, a support 13 is provided between the tension detection reel 12 and the bobbin 5 so that the bending strain is kept within 1% even when the dislocation conductor 1 hangs down. The support 13 uses a channel material such as vinyl chloride or metal, a plate, or a cylinder. Here, a channel material made of vinyl chloride is used.

  The support tool 13 is fixed below the travel line of the dislocation conductor 1, for example, at an interval of about 1 mm. Even if the dislocation conductor 1 loosens and hangs down, the dislocation conductor 1 is supported by the support tool 13. The bending strain applied to the dislocation conductor 1 can be suppressed to within 1%. Moreover, since it can respond to temporary drooping of the dislocation conductor 1 that occurs when the dislocation conductor 1 is unwound, the bending strain can be suppressed to within 1%.

  The electrode 14 according to the present invention shown in FIG. 5 is a copper electrode manufactured according to JIS C1100, and the soldering connection part 15 with the dislocation conductor is provided with a step 16 in a stepped manner. In FIG. 5, the step is two steps, but may be provided in two steps or multiple steps depending on the dislocation conductor used.

  In the case of the electrode of FIG. 4, the size of the step 16 is provided so as to substantially correspond to the strand thickness of the dislocation conductor 1 constituted by two rows and three layers of strands, for example, 0.5 mm. . The step difference of this electrode was made to correspond to the thickness of the strand so that bending distortion was not applied to the electrode soldering connection portion of the dislocation conductor.

  In addition, the electrode structure may be a method of forming a step by combining a copper plate with a plate made of fiber reinforced plastic, and any method can be used as long as the electrode structure having a step of the present invention is realized. A method may be used.

  Subsequently, two strands of dislocation conductors were soldered to one step of this electrode. This was repeated three times, and all six strands were connected to the electrodes by soldering. Further, the same electrode was prepared for the remaining end of the dislocation conductor and connected by the same soldering.

  Next, characteristics of the superconducting coil manufactured using the winding device and the electrode according to the present invention will be shown. The produced superconducting coil was cooled to liquid nitrogen temperature, the critical current was measured under a self-magnetic field, and a critical current value of 140 A was obtained. It was confirmed that this critical current value was influenced by the superconducting characteristics due to the magnetic field generated by the coil shape, and was not changed by bending strain during coil production.

  In order to measure the critical current and the hoop electromagnetic force under a high magnetic field, the superconducting coil of the present invention was attached to the inside of a heat insulating cylinder having an inner diameter of 300 mm, cooled to the liquid helium temperature, and an energization test was performed in a 14 T magnetic field environment. As a result, the critical current value was 360 A, and the hoop electromagnetic force applied to the dislocation conductor at that time was 136 MPa.

  Furthermore, excitation and demagnetization were repeated three times in a 14T magnetic field, but no change was observed in the critical current characteristics. Therefore, the superconducting coil according to the present invention has electrical and mechanical characteristics sufficient for practical use.

  It can be used for superconducting coils for large superconducting magnets used in superconducting power storage devices, nuclear fusion reactors and the like.

Regarding the present invention, FIG. 1A shows a schematic view of a cross-sectional structure of a superconductor wire when a resin is coated, and FIG. 1B shows a case where a metal material is attached. It is a perspective view of the structure of the dislocation conductor which concerns on this invention. It is an external view of the bobbin for winding used for the winding device concerning the present invention. It is a schematic diagram of the winding device according to the present invention. It is an electrode provided in the dislocation conductor which concerns on this invention. It is a schematic diagram of the winding device in which the bending direction of the dislocation conductor is reversed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dislocation conductor 2 Superconductor strand 3 Smooth surface of strand 4a Resin coated strand 4b Metal material sticking strand 5 Superconducting coil bobbin 6 Spacer 7 Winding device 8 Winding device 9 Superconducting coil 10 Unwinding device 11 Dislocation Conductor supply coil 12 Tension detection reel 13 Support 14 Electrode for superconducting coil 15 Solder connection site 16 Step 20 Winding device 21 Unwinding device 22 Tension detection reel 23 Direction change reel 24 Bobbin 25 Winding device

Claims (11)

A superconducting coil configured by winding a dislocation conductor formed by stacking high-temperature superconductor strands having a smooth layer on the outer periphery,
A superconducting coil, wherein a bending strain applied to the dislocation conductor during and after winding of the superconducting coil is 1% or less.   2. The superconducting coil according to claim 1, wherein the smooth layer is formed of one of a resin material layer and a metal material layer, or one or more layers.   The superconducting coil according to claim 1, wherein a spacer is provided between the dislocation conductor and the dislocation conductor that overlap each other in the superconducting coil. The superconducting coil according to any one of claims 1 to 3, wherein a thickness of the transition conductor is t (mm), and a winding inner diameter of a coil formed by winding the dislocation conductor is D (mm).
A superconducting coil characterized in that a thickness t (mm) of the dislocation conductor and a winding inner diameter D (mm) of the superconducting coil satisfy a relationship of the following formula.
0 <t ≦ D / 100   The bend imparted to the dislocation conductor forming the superconducting coil is a bend in the same direction and wound so that the bending strain is 1% or less. 5. A method for producing a superconducting coil according to any one of 4 above. In a winding device comprising at least one winding device component between the unwinding device and the winding device,
The unwinding device, the winding device, and the winding device components are arranged so that the bending strain applied to the dislocation conductor is 1% or less between the unwinding device and the winding device. Winding device. In a winding device comprising at least one winding device component between the unwinding device and the winding device,
A winding device, wherein a winding device, a winding device, and a winding device component are arranged so that the dislocation conductor is bent in the same direction. In a winding device comprising at least one winding device component between the unwinding device and the winding device,
Between the unwinding device and the winding device, the unwinding device, the winding device, and the winding device components are arranged so that the bending strain applied to the dislocation conductor is 1% or less,
A winding device, wherein a winding device, a winding device, and a winding device component are arranged so that the dislocation conductor is bent in the same direction.   In a winding device including at least one winding device component between the unwinding device and the winding device, the winding device component is a component that suppresses slack of the dislocation conductor during traveling. The winding device according to any one of claims 6 to 8.   An electrode for a superconducting coil provided with a step for connecting a dislocation conductor provided in accordance with the thickness of each high-temperature superconductor strand of a dislocation conductor formed by stacking high-temperature superconductor strands.   The superconducting coil according to any one of claims 1 to 4, wherein the superconducting coil electrode according to claim 10 is provided at an end of the superconducting coil.

Images