JP4774494B2 - Superconducting coil - Google Patents

Description

  The present invention relates to a superconducting conductor used for an electric device whose energization current fluctuates at a high speed, for example, energy storage, magnetic field application, transformer, reactor, current limiter, motor, generator and the like, and a superconducting coil using the same.

  Superconducting coils are put to practical use in various fields as high magnetic field generating means. On the other hand, the application of superconducting coils to AC devices such as transformers and reactors has not made much progress in practical use since there is a phenomenon that superconducting conductors generate losses due to AC.

  However, in recent years, since the development of superconducting wires with low AC loss due to the thinning of superconducting conductor wires, research on application to AC devices such as transformers has progressed, and various proposals have also been made regarding the structure of the superconducting coils. Has been done.

  As a superconducting conductor in this case, a superconducting wire using a metal superconductor that maintains a superconducting state at an extremely low temperature of 4K, which is the evaporation temperature of liquid helium, is mainly used as a practical superconducting material. Therefore, development of superconducting coils using oxide superconductors is also underway. This oxide superconductor is also called a high-temperature superconductor. When this high-temperature superconductor is used, there is an advantage that the operation cost is lower than when a metal superconductor is used.

  By the way, in an AC device such as a transformer where the energization current fluctuates at high speed, when a plurality of conductors are used in parallel, the conductors are transposed. This is to change the relative positions of the plurality of conductors so that the respective conductors are magnetically matched to reduce the induced voltage difference, thereby making the current sharing of each conductor uniform.

  The circulating current is induced by the difference in the induced voltage of each parallel conductor due to the magnetic flux generated by the energizing current, but in the case of a normal conductor such as copper or aluminum, the impedance is mainly a resistive component, The circulating current has a phase shifted by about 90 ° with respect to the energized current. Therefore, for example, even if 30% circulating current is generated, the current flowing through one conductor is a vector sum of 100% of the energized current and 30% circulating current having a phase difference of 90 °. The absolute value is about 105% because it is the square root of the sum of the squares, and the increase in the current value is small for the circulating current.

  On the other hand, when a superconducting wire is used as the conductor, the resistance is almost zero in the superconducting state, so that the impedance that determines the circulating current is almost determined by the inductance. Therefore, the circulating current is in phase with the energizing current. If the circulating current is 30%, this circulating current is added to the energizing current, and 130% of the current flows through the superconducting wire. When this current value reaches a critical current described in detail later, AC loss increases or drift increases.

  In addition, the superconducting conductor (or superconducting wire) used for the winding of the superconducting coil has a critical temperature, a critical current, and a critical magnetic field. That is, in order for the superconducting wire to maintain the superconducting state, the temperature, current, and magnetic field need to be not more than predetermined critical values.

  When a current exceeding the critical current flows through the superconducting wire due to the circulating current, the superconducting state changes from the superconducting state to the normal conducting state, that is, a normal conductor having resistance, and the superconducting wire may be damaged by Joule heat generation.

  Thus, in a coil using a superconducting wire, it is very important to suppress the circulating current. For this purpose, dislocation is performed as described above to suppress the circulating current. Note that the oxide superconducting wire has a property of being weaker in bending force than an alloy superconductor, and there is an allowable bending radius for exhibiting performance. Therefore, as the number of parallel lines increases, that is, as the number of dislocations increases, the number of unstable portions increases.

  A configuration of a superconducting coil aimed at reducing the cost by reducing the number of dislocations as unstable parts while suppressing the circulating current, thereby simplifying the dislocation work, is disclosed in Patent Document 1, for example. The gist of the invention described in Patent Document 1 is as follows. That is, “in a superconducting coil in which a plurality of superconducting wires are parallelized and wound, the dislocation is performed only at the end of the winding. In addition, the number of layers of the superconducting wires in parallel is the number of coils. By making it an integral multiple of 4 times (number x 4 times), the number of dislocations can be reduced, and the unstable parts can be reduced while suppressing the circulating current. In addition to being inexpensive, the circulating current can be suppressed with a small number of unstable parts, and therefore there is an advantage that high-speed excitation and demagnetization can be performed stably.

  FIG. 12 shows an example of the dislocation configuration of the superconducting coil described in FIG. In FIG. 12, for example, when the superconducting wire 3a, which is three stacked in the radial direction of the coil, is wound in the direction from the winding frame 1a to the winding frame 1b, the superconducting wire 3a is wound around the winding frame 1a. At the beginning, assuming that the coil is wound in the order of, for example, (A1, A2, A3) (not shown) from the coil inner diameter direction, first, (A3) is bent to the next turn at the dislocation portion 2b at the winding end. (A2, A1) and (A2, A1) are carried out, for example, the order of (A3, A2, A1) at the end of the winding on the winding frame 1b side. As described above, since the number of bends of the dislocation portion and the winding is reduced as compared with the conventional dislocation configuration described in FIG. 4 of Patent Document 1, the operation is remarkably simplified.

  Note that the description of the configuration example “the number of coil layers is an integral multiple of four times the number of parallel superconducting wires in parallel (number × 4 times)” is omitted here. Patent Document 1).

  By adopting the dislocation structure as described in Patent Document 1, the inductance of the superconducting wire constituting the conductor can be made uniform and the current sharing can be made uniform. Thereby, current capacity can be increased by increasing the number of superconducting wires in parallel, and additional loss due to the increase in the number of parallel wires can be eliminated.

  Next, the prior art of the oxide superconducting material (high temperature superconducting wire) will be described. As a preferable manufacturing method with high mass productivity of high-temperature superconducting wire, for example, a method of forming an oxide superconducting material in a film shape on a flexible tape substrate can be considered, and a gas phase method such as a laser ablation method or a CVD method is used. Development of a manufacturing method that has been underway is underway. In the high-temperature superconducting wire having the structure in which the oxide superconducting film is formed on the tape substrate as described above, the superconducting film is exposed in the outermost layer, and the exposed surface is not subjected to any stabilization treatment. Therefore, when a relatively large current is passed through such a high-temperature superconducting wire, local heat generation causes the superconducting film to locally transition from the superconducting state to the normal conducting state, and current transport becomes unstable. There was a problem.

  An oxide superconducting conductor that solves the above problems, has a high critical current value, can perform stable current transport, and does not deteriorate its stability even after long-term storage, and a method for producing the same. For this purpose, Patent Document 2 discloses a tape-shaped superconducting wire having the following configuration.

That is, “a flexible tape substrate, an intermediate layer formed on the tape substrate, an oxide superconducting film formed on the intermediate layer, and a thickness of 0.5 μm or more formed on the oxide superconducting film. A superconducting wire comprising a film (normally conducting metal layer) made of gold or silver. As an example of the embodiment described in Patent Document 2, an “yttria-stabilized zirconia layer or magnesium oxide layer is provided as an intermediate layer on a Hastelloy tape as a substrate, and a Y—Ba—Cu—O layer is provided thereon. A system oxide superconducting film is formed, and a coating film made of gold or silver is formed thereon. "
Furthermore, Patent Document 3 has the following configuration for the purpose of effectively dissipating generated heat due to AC loss and improving thermal stability by providing a normal conductive metal layer. A method for manufacturing a tape-shaped superconducting wire is disclosed.

  That is, according to the description of the publication, “a plurality of long-wavelength laser beams in which the high-temperature superconducting thin film of a tape-like material having a high-temperature superconducting thin film deposited on a substrate surface is arranged in parallel with one or more intervals. Irradiates in the longitudinal direction to make the irradiated portion non-superconducting (normal conducting), and selects the beam diameters and intervals of the plurality of long-wavelength laser beams so as to be positioned between the non-superconducting portions. A method for producing a high-temperature superconducting wire, characterized in that the width of a superconducting portion based on non-irradiation of laser light is controlled.

  However, when a tape-like superconducting wire having high mass productivity as described in Patent Documents 2 and 3 is used in an AC device, the AC loss generated in the superconducting wire is due to the shape anisotropy of the flat tape. There is a problem that alternating current loss in a vertical magnetic field acting perpendicularly to the flat surface of the tape becomes dominant and the alternating current loss increases. Further, in order to solve these problems with dislocation structures, some inventors of the present invention have made the following superconducting wire and wire material according to an international application (PCT / JP2004 / 009965). Discloses a superconducting coil.

  That is, the international application states that “a superconducting wire capable of suppressing AC loss is provided, and a superconducting coil using this superconducting wire can cancel the interlinkage magnetic flux due to a perpendicular magnetic field with respect to the wire with a simple configuration without dislocation. The purpose of this is to provide a superconducting coil with a low loss and to make the current shunt uniform by suppressing the circulating current in the wire due to the vertical magnetic field. In the superconducting wire made into a tape shape, at least a superconducting thin film portion as a superconducting layer is processed into a slit, and a parallel conductor obtained by electrically separating and paralleling a plurality of superconducting thin film portions having a rectangular cross section, that is, A superconducting coil formed by winding a plurality of element conductors in parallel and winding the superconducting wire is a structure or arrangement of a superconducting coil. A simple coil configuration without dislocations, at least part of which the vertical flux linkages acting between the conductor elements of the parallel conductors cancel each other due to the magnetic field distribution generated by the superconducting coil Is disclosed.

The superconducting conductor disclosed in the international application is, for example, an intermediate layer having a function of an electrical insulating layer is provided on a Hastelloy tape as a substrate, and a Y-Ba-Cu-O-based oxide is formed thereon as a superconducting layer. A material superconducting film is formed, and a normal conducting metal layer is formed thereon with a coating film made of, for example, gold or silver. The intermediate layer has a two-layer structure in which a cerium oxide (CeO ₂ ) layer is formed on a gadolinium zirconium oxide (Gd ₂ Zr ₂ O ₇ ) layer. The above superconducting conductor is slitted in the longitudinal direction of the superconducting conductor, and a flexible electrically insulating material such as epoxy resin or enamel is filled in the groove formed by slitting and the entire periphery of the conductor. Configure parallel conductors. (See the international application for details).

  Next, countermeasures against overcurrent such as transformer short-circuit accidents are described. When a transformer causes a short-circuit accident, a large short-circuit current flows through the coil and an excessive electromagnetic force works. In the case of a superconducting transformer, the current density is higher than that of a normal conducting transformer. In other words, if the current capacity is the same, the superconducting transformer has a smaller conductor cross-sectional area. Therefore, when the same electromagnetic force is applied to the conductor, the superconducting transformer applies more stress to the conductor. In the case of an oxide superconducting transformer, since the conductor is an oxide, the mechanical strength is relatively low, and it may not be able to withstand the electromagnetic force at the time of overcurrent.

A means for solving this problem is disclosed in Patent Document 4. To cite the description in the summary of Patent Document 4, that is, “a superconductivity formed by forming a spiral groove on the outer peripheral surface side of a cylindrical insulating winding frame and winding a tape-shaped superconducting wire along the groove. In the coil, a metal tape using a normal conductor such as copper, copper alloy, titanium, and stainless steel is wrapped around the superconducting wire and bound by a resin curing process, and the metal tape is further bonded to the superconducting wire. In this way, the electromagnetic force in the radial direction applied to the superconducting wire in the event of a short-circuit accident is supported by metal tape from the outer periphery, and the superconducting wire becomes normal conducting due to Joule heating due to overcurrent. If this happens, a part of the current is diverted to the metal tape to prevent coil burnout due to sudden temperature rise. "
JP-A-11-273935 (page 2-4, FIG. 1-4) JP-A-7-37444 (page 2-7, FIG. 1) JP-A-3-222212 (page 1-2, FIG. 3) JP 2001-244108 A

  By the way, according to the wire disclosed in the international application (PCT / JP2004 / 009965), a superconducting wire capable of suppressing AC loss can be obtained. When a superconducting coil having a portion having a relatively small radius of curvature is formed. Therefore, it is desired to provide a superconducting conductor that is unsuitable for the superconducting wire, can be easily wound even if the radius of curvature is relatively small, and is easier to manufacture.

  Furthermore, the critical current of a tape-like superconducting wire with high mass productivity as described in Patent Documents 2 and 3 and the international application (PCT / JP2004 / 009965) is approximately under a self-magnetic field and liquid nitrogen temperature (77K). 100A. In the state of the superconducting coil, the critical current further decreases due to the generation of the magnetic field, and the current that can be used as a device is significantly lower than the above-described critical current 100A.

  On the other hand, the required current capacity varies depending on the device and application. For example, when a large current is required, such as a low-voltage winding of a transformer, the methods described in Patent Documents 2 and 3 and the international application. May not be possible.

  In addition, as an AC device, for example, in the case of an inrush of excitation or a sudden short-circuit accident, a so-called overcurrent countermeasure that can withstand a current exceeding the rated current for a short time may be required. is there. As described above, in the tape-shaped superconducting wires described in Patent Documents 2 and 3 and the international application, a metal layer such as silver or gold is formed as a stabilizing layer. This metal layer is provided mainly for the purpose of improving the superconducting performance, and the thickness of this metal layer is generally 10 μm or less, which may be insufficient as a measure against overcurrent.

The present invention has been made to solve the above-described problems, and an object of the present invention is to use a superconducting coil having a relatively small radius of curvature using a parallel superconductor capable of suppressing AC loss. a readily wound even, providing easier superconducting coil manufacturing, further preventing burnout of the conductor due to overcurrent in excitation magnetic inrush or during sudden short circuit or the like, safety It is to provide a superconducting coil having a large capacity.

To solve the problems described above, the superconducting coil of the invention, electrically insulating material or a high-resistance material oxide superconducting wire coated with, superconducting conductors plurality of parallel disposed in the conductor width direction is a coil axis direction A plurality of secondary parallel conductors arranged in parallel in the coil axis direction as a unit, and a tertiary parallel conductor formed by laminating the secondary parallel conductor units in a plurality of layers in parallel in the coil radial direction. A superconducting coil that is wound, and the vertical interlinkage magnetic flux acting between the oxide superconducting wires of the superconducting conductor cancels each other due to the structure or arrangement of the superconducting coil due to the magnetic field distribution generated by the superconducting coil. It is assumed that a coil configuration having at least a portion that acts in this manner is provided (claim 1). In the above, as the oxide superconducting wire, known Bi-based oxide superconducting wires (Bi2223, Bi2212), Hg-based oxide superconducting wires, Tl-based oxide superconducting wires, and the like can be used. Other, but not oxide, it may also be a known MgB ₂ superconducting wire. Moreover, as said electrically insulating material, PVF (polyvinyl formal) is preferable, for example. Furthermore, as the high resistance material, an oxide layer obtained by oxidizing the surface of the superconducting wire or a Cr plating layer on the surface of the superconducting wire can be applied. Note that a plurality of oxide superconducting wires arranged in parallel in the conductor width direction can be bonded and fixed to each other, but can also be integrated with a resin, for example, as will be described later.

  According to the first aspect of the invention, the plurality of oxide superconducting wires formed in parallel electrically function as a multifilament superconductor, and the current splitting can be made uniform, and when applied to a coil for an AC device AC loss in a vertical magnetic field can be reduced. Further, according to the superconducting conductor configuration, even a superconducting coil having a relatively small radius of curvature can be easily wound and can be manufactured more easily.

  By the way, as described above, the superconducting thin film portion is also structurally separated in the tape-shaped superconducting wire disclosed in Patent Document 3, but the normal conducting thin film portion and the superconducting thin film portion are alternately formed. Therefore, eddy current loss occurs in the normal conducting thin film portion, and there is a problem that the loss increases. However, according to the superconducting conductor of the present invention, each oxide superconducting wire is electrically separated. Therefore, the problem as in Patent Document 3 does not occur.

  In the invention of claim 1, the cross-sectional shape of the oxide superconducting wire may be round, rectangular, or trapezoidal depending on the case, or the corners of the rectangle or trapezoid may be chamfered depending on the manufacturing method. There can be various variations, such as

As an embodiment of the invention of claim 1, the inventions of claims 2 to 9 below are preferable. That is, in the superconducting coil according to claim 1, the superconducting conductor is formed by arranging the oxide superconducting wire in parallel on a substrate surface made of a metal material or a non-conductive material (claim 2). For example, Cu or SUS (stainless steel) is preferable as the metal material, and GFRP is preferable as the non-conductive material.

Further, in the superconducting coil according to claim 1 or 2, the oxide superconducting wire in the superconducting conductor is twisted (claim 3). The twist can further reduce the AC loss. This reduction effect by the twist is a known effect obtained in the Nb ₃ Sn superconducting wire by the in-situ method. Such a twisted superconducting wire has a monofilament-like (single-core wire) characteristic due to superconducting contact between filaments, but the twist causes an AC loss against an external magnetic field having an arbitrary applied angle. Can be reduced.

Also, in the superconducting coil according to claim 1, the superconducting conductor is a plurality of oxide superconducting wires coated with a high resistance material arranged in parallel in the conductor width direction and integrated by soldering, or A plurality of oxide superconducting wires coated with a high resistance material are arranged in parallel in the conductor width direction on a substrate surface made of a metal material, and the plurality of oxide superconducting wires and the substrate are integrated by soldering. (Claim 4 ).

Furthermore, in the superconducting coil according to claim 1 , from the viewpoint of equalizing current sharing, when winding a tertiary parallel conductor formed by laminating the secondary parallel conductor units in a plurality of layers in parallel in the coil radial direction. The secondary parallel conductor units of the respective layers are dislocated (Claim 5 ).

Although details will be described later, before SL as in the invention of claim 1, in the secondary parallel superconductor unit, by arranging a number to electrically isolate the plurality of the oxide superconducting wire, the secondary parallel conductors or The tertiary parallel conductor becomes a conductor functioning as a multifilament, and the winding of the large current capacity superconducting coil can be facilitated, and current distribution can be made uniform and AC loss can be reduced. Further, based on the coil configuration, the vertical interlinkage magnetic flux acting between the oxide superconducting wires of the secondary parallel conductor unit has at least a portion that acts so as to cancel each other. The AC loss due to the vertical magnetic field is suppressed. In this case, dislocations are not necessary between the oxide superconducting wires in the coil axis direction, and the secondary parallel conductor units of each layer may be dislocated as in the invention of claim 5 , and the current capacity is increased by paralleling. The coil configuration can be facilitated .

Further, in view of the overcurrent protection, are preferred invention of superconducting coil below claims 6 to 9. That is, in the superconducting coil according to claim 1, at least one oxide superconducting wire in the superconducting conductor is replaced with a normal conducting wire made of a normal conducting material (claim 6 ) . A superconducting coil according et al in addition, in claim 1 of at least one superconducting conductor of the secondary parallel conductors shall become replaced by a normal conducting conductor made of normal conducting conductor material (claim 7 ).

  According to the above configuration, when the superconducting wire or the superconducting conductor is in a resistance state due to an overcurrent at the time of inrush or sudden short circuit, the current is diverted to the normal conducting wire or the normal conducting conductor, thereby generating Joule heat. Can prevent burnout.

  As described above, the inductance of the strands constituting the secondary strands is made uniform by arranging them in the axial direction of the coil, and the superconducting strands and the normal conducting strands are substantially the same. On the other hand, the normal conducting wire has an electric resistance, and the superconducting wire has a small negligible electric resistance in the normal use range. Accordingly, the impedance of the normal conducting wire becomes larger than that of the superconducting wire, and most of the current flows through the superconducting wire, and there is almost no heat generation due to the current in the normal conducting wire. This relationship is also established in a superconducting coil using a secondary parallel conductor including a normal conducting wire. Therefore, the loss due to the parallel arrangement of normal conducting wires is so small that it can be ignored. However, when an overcurrent exceeding the critical current flows through the superconducting wire, an electric resistance due to a magnetic flux flow is generated. Due to the relationship between the electrical resistance of the superconducting wire and the electrical resistance of the normal conducting wire, a current also flows through the normal conducting wire. Therefore, since an electric current can be sent through a normal conducting element wire, it can avoid flowing an excessive electric current through a superconducting element wire. As a result, it is possible to provide a superconducting coil that does not deteriorate characteristics even when an overcurrent exceeding the rated current occurs.

The position where the superconducting wire or the superconducting conductor is replaced with the normal conducting wire or the normal conducting conductor is not limited to one. The number and position of replacement depend on the design specifications of the superconducting coil. Furthermore, for example, all of the uppermost part or the lowermost part of the tertiary parallel conductor in the coil axis direction can be used. Also, the replacement position can be all one layer in the coil layer direction, but from the viewpoint of supporting electromagnetic force at the time of overcurrent, make the normal conducting wire have both the function of current shunting and the function of supporting electromagnetic force. Is preferred. From this viewpoint, the invention of claim 8 below is preferable.

That is, in the superconducting coil according to claim 5 , among the plurality of secondary parallel conductors in the tertiary parallel conductor, the secondary parallel conductor in the outermost layer is replaced with a secondary parallel conductor made of a normal conductive conductor. The outermost layer made of a conductive conductor is configured not to dislocation (claim 8 ). In this case, the plurality of normal conducting conductors are insulated and coated in the same manner as the superconducting wire.

  As the material for the normal conducting wire or the normal conducting conductor, a normal conductive material such as copper, copper alloy, titanium, stainless steel, etc. can be used. However, depending on the coil specifications, when supporting electromagnetic force is important. It is desirable to use a material having high mechanical strength even if the electrical conductivity is relatively small. In some cases, a material having a high electrical conductivity and a material having a high mechanical strength can be combined.

Further, from the viewpoint of emphasizing the electromagnetic force support at the time of overcurrent, the invention of claim 9 below is preferable. That is, in the superconducting coil according to claim 5 , out of the plurality of secondary parallel conductors in the tertiary parallel conductor, the outermost secondary parallel conductor is an electromagnetic force support made of a normal conductive material or a high-strength insulating material. It shall be replaced with a member (claim 9 ).

According to the present invention, using a parallel superconducting conductor capable inhibition of AC loss, a possible wound easily even at relatively small superconducting coil radius of curvature, manufacturing is easier superconducting coil was provided, further, to prevent the burnout of the conductor due to overcurrent in excitation magnetic inrush or during sudden short circuit or the like, it can be provided a secure large superconducting coils.

  An embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 is a schematic cross-sectional view of a superconducting conductor showing an embodiment of the present invention. FIG. 1 (a) shows a case where a round wire is used as the oxide superconducting wire, and (b) and (c) show a rectangular cross-section. In the case of using the wire rods shown in FIG. In FIG. 1, the oxide superconducting wires indicated by 20a, 20b and 20c, respectively, are covered with an electrically insulating material or a high resistance material and arranged in parallel in the conductor width direction. It is configured as a parallel superconducting conductor.

  As the oxide superconducting wire, known wires as described above can be applied. For example, Bi-based oxide superconducting wires (Bi2223, Bi2212) are used. For example, PVF (polyvinyl formal) is used as the electrically insulating material, and a Cr plating layer is used as the high resistance material. A plurality of wires arranged in parallel in the conductor width direction are bonded and fixed to each other, or integrated with resin as in the embodiment described later, and applied to a superconducting coil, the above-described parallel superconducting The conductor is wound around the coil central axis. The configuration of the superconducting coil will be described later.

  Next, an embodiment of a superconducting conductor different from that shown in FIG. 1 will be described with reference to FIGS. FIG. 2 shows an embodiment in which oxide superconducting wires 20a, 20b, and 20c covered with an electrically insulating material are arranged in parallel on the surface of a substrate 31 made of a metal material or a non-conductive material. FIG. 3 shows an embodiment in which oxide superconducting wires 21a, 21b, and 21c coated with a high resistance material are arranged in parallel on the surface of the substrate 31. FIG.

  FIGS. 4 and 5 show embodiments in which the outer periphery of the superconducting conductor shown in FIGS. 1 and 2 is integrated by insulating coating with, for example, an epoxy resin. According to this embodiment, reliability with respect to electrical insulation is improved, and handling of the superconducting conductor is facilitated by integration.

  FIG. 6 shows the oxide superconducting wires 20a, 20b, 20c and the substrate 31 joined together by, for example, an epoxy resin, or an oxide coated with a high-resistance material according to claim 5 A plurality of superconducting wires (21a, 21b, 21c) are arranged in parallel in the conductor width direction on the surface of the substrate 31 made of a metal material, and the plurality of oxide superconducting wires and the substrate are integrated by soldering. An embodiment is shown. The superconducting conductor according to claim 5 is configured such that the substrate 31 is omitted and a plurality of oxide superconducting wires (21a, 21b, 21c) coated with a high resistance material are arranged in parallel in the conductor width direction. It is good also as what is arrange | positioned and integrated by soldering.

  Next, an embodiment of the superconducting coil will be described with reference to FIGS.

FIG. 7 shows a reference form before reaching the embodiment relating to the invention of claim 1 . The superconducting coil shown in FIG. 7 is a superconducting coil in which a secondary parallel conductor 50 formed by arranging a plurality of superconducting conductors 40 in parallel in the coil axial direction is wound in a single layer or a plurality of layers, and the axial direction of the superconducting coil. Based on the symmetry of the above, the magnetic flux distribution generated by the superconducting coil acts so that the vertical flux linkages acting between the superconducting wires of the secondary parallel conductor 50 cancel each other (for details, refer to the international application PCT / JP2004 / 009965).

  In FIG. 7, the superconducting conductors 40 are denoted by numbers 1 to 4 for the convenience of explanation. In the case of the superconducting coil of the embodiment of FIG. 7, it is not necessary to transpose the secondary parallel conductor 50. Therefore, the numbers of the superconducting conductors in all the secondary parallel conductors 50 are set to (1, 2, 3, 4), (1, 2, 3, 4),. 3) and 4), and this row is wound so as to be an array that repeats in the layer direction.

Next, FIG. 8 will be described. FIG. 8 is a schematic cross-sectional view of a superconducting coil showing an example of an embodiment of the present invention . FIG. 8A shows a superconducting conductor 40 having a plurality of oxide superconducting wires 20b which are electrically separated and arranged in parallel on the surface of the substrate 31. FIG. As the superconducting conductor 40, a superconducting conductor as shown in FIGS. 1 to 6 can be applied.

  FIG. 8B shows a configuration in which four superconducting conductors 40 shown in FIG. 8A are arranged in parallel in the coil axis direction, and this becomes the secondary parallel conductor 50. In FIG. 8B, the four superconducting conductors 40 are electrically insulated from each other.

  In the case of FIG. 8B, since the inductances of the superconducting conductors 40 arranged in parallel are the same, the superconducting conductors 40 in the secondary parallel conductor 50 do not need to be displaced. As a result, the secondary parallel conductor 50 is equivalent to a conductor having a current capacity that is several times that of the superconducting conductor 40 in parallel.

  Next, FIG. 8C will be described. FIG. 8C shows a tertiary parallel conductor 60 in which secondary parallel conductors 50 are laminated in parallel to form a conductor. In FIG. 8C, the secondary parallel conductors 50 are electrically insulated. Since the inductances of the stacked secondary parallel conductors 50 are different due to the position in the coil radial direction, it is necessary to perform dislocation. As this dislocation structure, by adopting the dislocation structure as described in the above-mentioned Patent Document 1, that is, the structure in which the dislocation is performed at the end of the coil in the axial direction, the inductance of the superconducting wire constituting the conductor is made uniform. Further, the current sharing can be made uniform, and the current density as a coil can be prevented from lowering. Details will be described later.

  Next, FIG. 8D will be described. FIG. 8D shows a schematic cross section of a coil configuration in which the tertiary parallel conductor 60 is wound in a plurality of layers in the coil radial direction and wound in a plurality of turns in the coil axial direction. In FIG. 8D, the number of layers is omitted and indicated by a broken line. Further, reference numeral 54 denotes a coil flange, and 55 denotes a winding frame. Note that the winding frame does not have to be cylindrical as illustrated, and may have various shapes such as a racetrack shape or a rectangle with rounded corners.

  By configuring the superconducting coil as in the embodiment of FIG. 8 described above, the current capacity of the coil can be ensured by 4 parallels × 3 superpositions of the superconducting conductors 40, that is, 12 times the current capacity. When a large current capacity is to be achieved, as shown in FIG. 8, a unit parallel conductor with a small current capacity is used as in the present invention as compared with the case where a superconducting element wire having a large current capacity is used as the conductor wire. The configuration is easier to manufacture and less expensive.

  Further, the vertical interlinkage magnetic field acting on the electrically isolated secondary parallel conductor 50, the superconducting conductor 40 constituting the electrically isolated secondary parallel conductor 50, and the electrically isolated oxide superconducting wire 20b is disclosed in the international application. As described above, based on the symmetry of the superconducting coil in the axial direction, the superconducting wires as a whole act so as to cancel each other, so that AC loss based on the vertical magnetic field is suppressed. Further, the divided oxide superconducting wire 20b can behave as an independent filament, and AC loss can be further reduced.

  In the case of FIG. 8, it is desirable to displace the secondary parallel conductor, which will be described in the next FIG. FIG. 9 shows an embodiment of a superconducting coil simplified to explain the dislocation configuration. The embodiment of FIG. 9 is a tertiary parallel configuration in which four secondary conductive conductors 40 arranged in parallel in the coil axis direction are stacked in three layers in the radial direction and the normal conductive conductor 70 is arranged in the outermost layer. A superconducting coil formed by winding a conductor 60a as a conductor unit is shown.

  In the case of performing dislocation, as described above, a configuration in which “the number of coil layers is an integer multiple of four times the number of parallel superconducting wires (number × 4 times)” is preferable. An embodiment in which three layers (secondary parallel conductors) × 4 times and 12 layers are shown, and each layer is shown as one layer, two layers,..., 12 layers below FIG. In addition, for the convenience of explanation of dislocation, the superconducting conductors 40 are denoted by numbers 1 to 12 for the respective superconducting conductors 40.

  When the third parallel conductors 60a are arranged so as to overlap each other as shown in FIG. 9, the inductance changes between the secondary parallel conductors as in FIG. 8, so that at least the superconducting conductor 40 needs to be dislocated between the layers. By performing the dislocation, the inductance between the secondary parallel conductors becomes equal.

  Even if the normal conductor does not dislocation, it depends on the material, temperature, number of layers, operating frequency, etc. of the normal conductor, but usually the current flowing in the normal conductor is limited by the resistance, and heat generation is often not a problem. Therefore, in FIG. 9, the structure which does not displace between the conductors corresponded to the secondary parallel conductor of the normal conducting conductor 70 is shown. When dislocations are performed as necessary, necessary dislocations are performed between the tertiary parallel conductors.

  In FIG. 9, current flows in from the upper left side of the figure along the thick arrow and flows out from the upper right side of the figure, and in the meantime, it is indicated by a thick line between the upper and lower layers of the tertiary parallel conductor 60 a in the figure. Thus, each superconducting conductor 40 dislocations sequentially. For example, among the three layers of the tertiary parallel conductor 60a closest to the coil central axis 14, the secondary parallel conductor closest to the coil central axis indicated by numbers 1 to 4 is introduced from the position A shown in the upper left of the figure, and is illustrated. Through B, C, D, E, F,..., W, it is derived to a position X shown in the upper right of the figure, and by shifting as described above, the inductance between the secondary parallel conductors becomes equal.

  Next, FIG. 10 will be described. FIG. 10 shows an embodiment different from that in FIG. 8, and as a countermeasure against overcurrent, one superconducting conductor 40 is used as a normal conducting conductor material among the plurality of superconducting conductors 40 in the secondary parallel conductor 50 shown in FIG. An embodiment in which a normal conductive conductor 70 is used is shown. In FIG. 10, the secondary parallel conductor is indicated by 50a, and the tertiary parallel conductor is indicated by 60a. Other members are the same as in FIG.

  FIG. 10A shows a superconducting conductor 40 similar to that shown in FIG. When these are arranged side by side in the axial direction of the superconducting coil as shown in FIG. 10B, the secondary parallel conductor 50 a is configured including the normal conducting conductor 70, not all of the superconducting conductor 40. As described above, the inductances of the disposed conductors are the same.

  The normal conductive conductor 70 always has an electric resistance, whereas the superconductive conductor 40 has an electric resistance that is negligibly small in a normal state. Therefore, current flows through the superconducting conductor 40, there is no Joule heat generation in the normal conducting conductor 70, and loss due to the arrangement of the normal conducting conductor does not increase. The normal conductive conductor 70 may be a tape-shaped conductor or a conductor made of a stranded wire.

  FIG. 10C shows a tertiary parallel conductor 60a in which three layers of secondary parallel conductors 50a are stacked to form a conductor. FIG. 10D shows a coil formed by winding the tertiary parallel conductor 60a four turns per layer as in FIG. The number of layers is omitted.

  At normal times, the current flows through the superconducting conductor 40. However, when an overcurrent flows as in the case of the inrush of the transformer, a current exceeding the critical current flows in the superconducting conductor 40. When the critical current is exceeded, an electrical resistance is generated in the superconducting conductor 40. In this case, the current flowing through each conductor is determined by the relationship between the electrical resistance of the superconducting conductor 40 and the electrical resistance of the normal conducting conductor 70.

  By the way, the critical current after energization does not decrease even if an overcurrent flows up to a predetermined magnification of the initial critical current (a magnification that varies depending on the wire), but if an overcurrent that exceeds this is exceeded, the critical current after energization decreases. It is known that so-called critical current deterioration occurs.

  In the present invention, by appropriately setting the electric resistance of the superconducting conductor 40 and the electric resistance of the normal conducting conductor 70, the current at the time of overcurrent can be shared with the normal conducting conductor 70, so the current flowing through the superconducting conductor 40 is reduced. As a result, deterioration of the critical current of the superconducting conductor 40 can be suppressed.

  Next, FIG. 11 will be described. FIG. 11 shows an embodiment in which the outermost secondary parallel conductor of the multiple parallel secondary conductors in the tertiary parallel conductor is replaced with an electromagnetic force support member 71 made of a normal conducting material or a high-strength insulating material. Show.

  Since FIGS. 11A and 11B are the same as FIGS. 10A and 10B, description thereof is omitted. FIG. 11 (c) shows a tertiary parallel conductor 60a in which three layers of secondary parallel conductors 50a are made into a conductor to further overlap an electromagnetic force support member 71 made of a normal conducting material. FIG. 11 (d) shows a coil formed by winding a plurality of turns using the tertiary parallel conductor of FIG. 11 (c). Note that the electromagnetic force support member 71 may be divided into four in the coil axis direction, as in FIG.

  The effect of the normal conductive conductor 70 is the same as that of FIG. The superconducting coil as shown in FIG. 11 can provide a superconducting coil that can withstand a large electromagnetic force. In addition, as a material of this mechanical support material 71, high strength metal materials, such as stainless steel, can be used. Further, when the stabilization function is left to the normal conductor 70 and the electromagnetic force support member 71 is left only to the electromagnetic force support function, the mechanical support material 71 is made of a high-strength insulating material such as glass tape. You can also

  As described above, the embodiments of various superconducting coils of the present invention have been described with respect to the solenoid coil. However, in addition to the solenoid coil, a superconducting coil such as a pancake coil or a saddle coil mainly used for a superconducting rotating machine. In addition, the present invention can be applied.

The typical sectional view of the superconducting conductor which shows the embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a superconducting conductor showing an embodiment different from FIG. 1. FIG. 3 is a schematic cross-sectional view of a superconducting conductor showing an embodiment different from FIG. 2. FIG. 2 is a schematic cross-sectional view of a superconducting conductor showing an embodiment further different from FIG. 1. FIG. 5 is a schematic cross-sectional view of a superconducting conductor showing an embodiment different from FIG. 4. FIG. 5 is a schematic cross-sectional view of a superconducting conductor showing an embodiment further different from FIG. 4. The typical sectional view of the superconducting coil which shows the reference form before reaching the embodiment of the present invention. The typical sectional view of the superconducting coil which shows the embodiment of the present invention . FIG. 9 is a diagram illustrating a dislocation configuration in an embodiment different from FIG. 8. Schematic sectional view of the superconducting coil showing the different embodiments and FIG. FIG. 11 is a schematic cross-sectional view of a superconducting coil showing an embodiment different from FIG. 10. The figure which shows an example of the dislocation structure of the superconducting coil disclosed by patent document 1. FIG.

1-12 Number of each superconducting conductor 14 Coil central axis 20a-20c, 21a-21c Oxide superconducting wire 31 Substrate 36 Electrical insulating material 40 Superconducting conductor 50, 50a Secondary parallel conductor 54 Coil flange 55 Reel 60, 60a Tertiary parallel conductor 70 Normal conducting conductor 71 Electromagnetic force support member

Claims (9)

An electrically insulating material or high-resistance material oxide superconducting wire coated with the superconducting conductors plurality of parallel disposed in the conductor width direction is a coil axis direction, the secondary formed by parallel arrangement a plurality coil axis direction A superconducting coil in which a parallel conductor is a unit, and a secondary parallel conductor unit is laminated in parallel in a plurality of layers in the radial direction of the coil, and is wound by a single layer or a plurality of layers, and a magnetic field generated by the superconducting coil At least a part has a part in which vertical flux linkages acting between the oxide superconducting wires of the superconducting conductor cancel each other due to the structure or arrangement of the superconducting coil due to the distribution. A superconducting coil comprising a coil configuration . A superconducting coil according to claim 1, wherein the superconducting conductor on the substrate surface made of a metallic material or non-conductive material, the superconducting coil, wherein the oxide superconducting wire arranged in parallel. A superconducting coil according to claim 1 or 2, the superconducting coil, characterized by comprising twisted oxide superconducting wire in the superconducting conductor. 2. The superconducting coil according to claim 1, wherein the superconducting conductor includes a plurality of oxide superconducting wires coated with a high resistance material arranged in parallel in the conductor width direction and integrated by soldering, or a high resistance material. A plurality of oxide superconducting wires coated with metal are arranged in parallel in the conductor width direction on a substrate surface made of a metal material, and the plurality of oxide superconducting wires and the substrate are integrated by soldering. Features superconducting coil . 2. The superconducting coil according to claim 1 , wherein when the third parallel conductor formed by laminating the secondary parallel conductor units in a plurality of layers in parallel in the coil radial direction is wound, the secondary parallel conductor units of the respective layers are dislocated. A superconducting coil characterized by comprising A superconducting coil according to claim 1, wherein at least one of the oxide superconducting wire in a superconducting conductor, a superconducting coil, characterized by comprising replacing the normal conducting wire formed of normal conducting conductor material. The superconducting coil according to claim 1 , wherein at least one of the secondary parallel conductors is replaced with a normal conductive conductor made of a normal conductive material. 6. The superconducting coil according to claim 5 , wherein, among the plurality of secondary parallel conductors in the tertiary parallel conductor, the secondary parallel conductor in the outermost layer is replaced with a secondary parallel conductor made of a normal conductive conductor. A superconducting coil characterized in that the outermost layer is configured not to dislocation. 6. The superconducting coil according to claim 5 , wherein the outermost secondary parallel conductor among the multiple secondary parallel conductors in the tertiary parallel conductor is an electromagnetic force supporting member made of a normal conductive material or a high-strength insulating material. A superconducting coil characterized by being replaced.