JP2004259737A - Superconducting transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superconducting transformer that has a low % impedance and, in addition, an entirely simple cooling structure, electromagnetic force supporting structure, and insulating structure, and can prevent the occurrence of dielectric breakdowns by maintaining the insulating characteristics between a high-voltage winding and a low-voltage winding. <P>SOLUTION: The low-voltage winding 2 and high-voltage winding 3 each having one or a plurality of layers of cylindrically wound superconducting coil are provided concentrically around the center axis of an iron core 1. The superconducting coils are constituted by winding superconducting wires around a cylindrical bobbin along spiral grooves formed on the outer peripheral surface of the bobbin and winding electromagnetic force supporting tapes around the superconducting wires in overlapping states and binding the tapes with the wires, and then, installing a plurality of cooling ducts to the outer peripheral surface of the cylindrical bobbin in the direction of its cylindrical axis. In addition, an insulating cylinder 10 made of an electrical insulating material is concentrically provided between the low- and high-voltage windings 2 and 3 at prescribed intervals from the outer peripheral surface of the winding 2 and the inner peripheral surface of the winding 3. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a superconducting transformer formed by winding a superconducting wire.
[0002]
[Prior art]
Superconducting coils are used in various fields as high magnetic field generating means. On the other hand, the practical application of superconducting coils to AC equipment such as transformers has not progressed much because of the phenomenon in which superconducting conductors generate losses due to alternating current.
[0003]
However, in recent years, since superconducting wires with small AC loss due to thinning of superconducting conductor wires were developed, research on application to AC equipment such as transformers has progressed, and the configuration of superconducting transformers will also be described later. Various proposals have been made (for example, see Patent Documents 1 to 3).
[0004]
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 4 K, which is the evaporation temperature of liquid helium, is mainly used as a practical superconducting material. Then, as described in the above-mentioned patent document, development of a superconducting coil using an oxide superconductor is also in progress. This oxide superconductor is also called a high-temperature superconductor, and when using this high-temperature superconductor, the cooling temperature is higher than when using a metal superconductor. Good, there is an advantage that the operating cost is low.
[0005]
FIG. 3 shows a schematic partial sectional view of the superconducting transformer. 3, the core 1, the inner coil 2, and the outer coil 3 are arranged concentrically with the center axis of the core as an axis, and the center axis is on the left side of the core 1 in FIG. Therefore, the inner coil 2 is arranged on the outer diameter side of the central shaft portion of the iron core 1, and the outer coil 3 is further arranged on the outer diameter side. In the case of a transformer, the inner coil is generally a low-voltage winding and the outer coil is a high-voltage winding.
[0006]
When a high-temperature superconductor is used, the inner coil 2 and the outer coil 3 are housed and supported in a cooling vessel (not shown) and are immersed and cooled in liquid nitrogen. Furthermore, in order to align each coil arranged concentrically with the winding and to support each coil, a winding is performed by forming a circular groove on a disk at both ends in the axial direction of the winding. A wire support member 9 is provided, which sandwiches and supports each coil, and is fixed by a through bolt (not shown).
[0007]
In the case of the transformer, the ratio of the number of turns of the low-voltage winding to that of the high-voltage winding is substantially proportional to the transformation ratio. For example, in the case of a transformer having a transformation ratio of 2, the number of turns of the high-voltage winding is almost twice the number of turns of the low-voltage winding. In this case, when the low-voltage winding has one layer, the high-voltage winding is generally configured as a two-layer structure. FIG. 3 shows a schematic structural diagram in the case of a transformation ratio of 2, where the inner coil (low-voltage winding) has two layers and the outer coil (high-voltage winding) has four layers.
[0008]
Incidentally, in the superconducting transformer, the configuration of the superconducting coil as the transformer winding is important from the viewpoint of cooling the superconducting wire and supporting the electromagnetic force generated in the superconducting coil.
[0009]
Patent Literature 1 discloses a basic superconducting transformer in which a spiral groove is formed on the outer peripheral surface side of a cylindrical bobbin made of an electrically insulating material, and a superconducting wire is wound along this groove to form a superconducting coil. A strategic configuration is disclosed.
[0010]
Patent Document 2 discloses a superconducting coil, which was previously filed by the same applicant as the present invention and has a preferable structure with respect to cooling of the superconducting wire and supporting of an electromagnetic force generated in the superconducting coil. . In particular, the configuration described in FIG. 6 and FIG. 7 of Patent Document 2 is particularly preferable from the above viewpoint, and the gist of the configuration is “a tape-shaped superconducting wire wound on the outer peripheral side of a bobbin. After winding a binding tape such as glass or polyester fiber impregnated with semi-cured resin on the outer periphery, the resin is cured to bind the superconducting wire from the outside. A plurality of cooling ducts through which liquid nitrogen flows. "
[0011]
Further, Patent Literature 3 discloses a further improvement of the superconducting coil described in Patent Literature 2, which protects the superconducting wire from being damaged by an excessive electromagnetic force applied in the event of a short circuit or the like. It is an object of the present invention to provide a mechanically and thermally reliable superconducting coil for an induction device, which skillfully prevents excessive heat generation due to transition of a superconducting wire into a normal conducting state due to electric current.
[0012]
2 shows the structure of the superconducting coil disclosed in FIG. 1 of Patent Document 3, FIG. 2 (a) is a longitudinal side view of the superconducting coil, and FIG. 2 (b) is a cross-sectional plan view of FIG. 2 (a). Show. In the configuration shown in FIG. 2, a metal tape 6 of a normal conductor is wound around the outer peripheral side of the tape-shaped superconducting wire 5 wound around the outer peripheral surface side of the winding frame 4. As the metal tape 6, a tape made of copper or copper alloy, titanium, stainless steel, or the like that can be used at a very low temperature is employed. , And an adhesive such as an epoxy resin is applied to a peripheral area thereof, and is subjected to a hardening treatment so as to be firmly bound. With this configuration, a radially outward force applied to the outer coil (high-voltage winding) 3 can be supported.
[0013]
Further, the metal tape 6 functions as a heat transfer material to radiate Joule heat generated in the superconducting wire 5 to a refrigerant (liquid nitrogen or the like) flowing therearound. As a result, the Joule heat of the superconducting wire 5 due to a short-circuit current is generated. The resulting rapid temperature rise can be suppressed.
[0014]
[Patent Document 1]
JP-A-1-286304 (page 1-2, FIG. 1-3)
[Patent Document 2]
JP-A-2000-133515 (pages 5-6, FIGS. 6, 7)
[Patent Document 3]
JP 2001-244108 A (page 3-4, FIG. 1)
[0015]
[Problems to be solved by the invention]
Incidentally, since the transformer is used at a high voltage, a predetermined insulation performance is required between the superconducting windings (between turns), between the coils, and between the high-voltage winding and the low-voltage winding. Among them, it is possible to easily obtain a configuration having a predetermined insulation performance by appropriately setting an insulation distance between turns and between layers.
[0016]
However, the distance between the high-voltage winding and the low-voltage winding (α in FIG. 3) cannot be arbitrarily set because there is a correlation with the% impedance value of the transformer. In the case of the conventional transformer as shown in FIG. 3, the interval α between the inner peripheral surface of the high-voltage winding and the outer peripheral surface of the low-voltage winding is determined to a predetermined value based on% impedance which is a specification of the transformer. . On the other hand, the breakdown voltage between the high-voltage winding and the low-voltage winding is determined by the insulation characteristics of liquid nitrogen. there's a possibility that. That is, when designing a transformer having a small% impedance, the distance α between the high-voltage winding and the low-voltage winding must be reduced, so that there is a problem that a required insulation distance cannot be maintained.
[0017]
The present invention has been made to solve the above problems, and an object of the present invention is to improve the insulation performance between a high-voltage winding and a low-voltage winding even in the case of a transformer having a small% impedance. An object of the present invention is to provide a superconducting transformer capable of holding and preventing dielectric breakdown, and having a simple cooling structure, electromagnetic force supporting structure and insulating structure as a whole.
[0018]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a low-voltage winding and a high-voltage winding having one or more cylindrical superconducting coils in a concentric cylindrical shape with the center axis of an iron core as an axis. In the superconducting transformer housed and supported in a cooling vessel, the superconducting coil forms a spiral groove on the outer peripheral surface side of a cylindrical winding frame made of an electrically insulating material, and the superconducting wire is formed along the groove. Is wound around the superconducting wire, and a tape for supporting an electromagnetic force is wound around the outer periphery thereof for binding, and a plurality of cooling ducts are provided in the cylindrical axis direction on the outer peripheral surface side of the cylindrical winding frame. Further, an insulating cylinder made of an electrically insulating material is provided between the low-voltage winding and the high-voltage winding with a predetermined gap between the outer peripheral surface of the low-voltage winding and the inner peripheral surface of the high-voltage winding. Are arranged in the concentric cylindrical shape. Invention).
[0019]
According to the above-described invention, by inserting an insulating cylinder between the high-voltage winding and the low-voltage winding, the dielectric strength between the high-voltage winding and the low-voltage winding can be improved, and dielectric breakdown can be prevented. Further, since the cylindrical superconducting coil serving as a unit of the winding is configured to be capable of independently supporting and cooling the electromagnetic force by the above-described configuration, the insulating cylinder is configured to support the electromagnetic force and the cooling configuration. It is possible to assemble independently of the above, and the overall structure is simplified.
[0020]
As an embodiment of the invention of claim 1, the following inventions of claims 2 to 6 are preferable. That is, in the superconducting transformer according to the first aspect, the tape for supporting the electromagnetic force is a semi-cured resin-impregnated glass bind tape (the invention of the second aspect). Further, in the superconducting transformer according to the first aspect, the tape for supporting the electromagnetic force is a metal tape of a normal conductor (the invention of the third aspect). The operational effects according to these embodiments are as described above with reference to Patent Documents 2 and 3.
[0021]
Further, as an embodiment relating to the insulating cylinder, the following invention of claim 4 is preferable. That is, in the superconducting transformer according to any one of claims 1 to 3, the insulating cylinder is made of FRP mainly composed of epoxy resin and glass fiber.
[0022]
Further, in the superconducting transformer according to the fourth aspect, the insulating cylinder is formed by winding a semi-cured epoxy glass prepreg sheet a plurality of times and performing a curing treatment (the invention of the fifth aspect). This facilitates manufacture of the insulating cylinder.
[0023]
Furthermore, the present invention can be configured as in the invention of claim 6 described below. That is, in the superconducting transformer according to claim 4, the insulating cylinder is formed by winding a thin insulating sheet of the FRP a plurality of times, applying an epoxy resin, and performing a curing treatment. This is suitable for the case of manufacturing an insulating cylinder of a relatively large device, and it is suitable for a case where winding of a sheet is difficult.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0025]
FIG. 1 is a schematic partial sectional view of a superconducting transformer according to an embodiment of the present invention. 1, members having the same functions as the members in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0026]
The difference between the embodiment of FIG. 1 and the superconducting transformer shown in FIG. 3 is that, in FIG. 1, an electrically insulating material is provided between an inner coil (low-voltage winding) 2 and an outer coil (high-voltage winding) 3. Is formed in a concentric cylindrical shape centered on the central axis of the iron core 1 with a predetermined gap between the outer peripheral surface of the low-voltage winding 2 and the inner peripheral surface of the high-voltage winding 3. .
[0027]
The material of the insulating cylinder 10 is FRP mainly composed of epoxy resin and glass fiber as described above, and a semi-cured epoxy glass prepreg sheet wound a plurality of times and cured, or the FRP. It is assumed that a thin insulating sheet is wound a plurality of times, coated with an epoxy resin, and cured. The thickness of the insulating cylinder 10 and the size of the gap are determined by design based on the specifications of the superconducting transformer.
[0028]
The gap between the outer peripheral surface of the low-voltage winding and the inner peripheral surface of the high-voltage winding and the insulating cylinder is preferably the same over the entire circumference. The reason is that, for example, when the insulating cylinder is made of FRP (dielectric constant 4.5) and the cooling medium is liquid nitrogen (dielectric constant 1.3), if the gaps are unbalanced, electric field concentration occurs, which is not preferable.
[0029]
As shown in FIG. 2, the configuration of each coil forming the low-voltage winding and the high-voltage winding is such that a spiral groove is formed on the outer peripheral surface side of a cylindrical winding frame made of an electrically insulating material. A superconducting wire is wound along the superconducting wire, and a tape for supporting an electromagnetic force is wound around the superconducting wire and bound, and a plurality of the superconducting wires are wound in a cylindrical axis direction on an outer peripheral surface side of the cylindrical reel. It has a cooling duct.
[0030]
【The invention's effect】
According to the present invention, as described above, the low-voltage winding and the high-voltage winding each having one or more cylindrical superconducting coils are arranged in a concentric cylinder centering on the central axis of the iron core, and the cooling is performed. In a superconducting transformer housed and supported in a container,
In the superconducting coil, a spiral groove is formed on the outer peripheral surface side of a cylindrical winding frame made of an electrically insulating material, and a superconducting wire is wound along the groove. A tape for force support is wound and bound, and a plurality of cooling ducts are provided in a cylindrical axis direction on an outer peripheral surface side of the cylindrical winding frame. Between the wire and the insulating cylinder made of an electrically insulating material, since the outer peripheral surface of the low-voltage winding and the inner peripheral surface of the high-voltage winding are disposed in the concentric cylindrical shape with a predetermined gap, respectively.
Even in the case of a transformer with a small% impedance, the insulation performance between the high-voltage winding and the low-voltage winding can be maintained and insulation breakdown can be prevented, and the cooling structure, electromagnetic force support structure, and insulation structure are generally simple. A superconducting transformer can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic partial sectional view of a superconducting transformer according to an embodiment of the present invention. FIG. 2 is a diagram showing a structure of a superconducting coil disclosed in Patent Document 3 and also according to an embodiment of the present invention. Schematic partial cross-sectional view of an example of a conventional superconducting transformer [Explanation of reference numerals]
1: iron core, 2: inner coil (low-voltage winding), 3: outer coil (high-voltage winding), 4: winding frame, 4a: cooling duct, 5: superconducting wire, 6: metal tape, 9: winding support member , 10: insulating cylinder, α: distance between high-voltage winding and low-voltage winding.

Claims (6)

A superconducting transformer formed by arranging a low-voltage winding and a high-voltage winding having one or more layers of cylindrical superconducting coils in a concentric cylinder having the center axis of the iron core as an axis and storing and supporting the coils in a cooling container. In the vessel
In the superconducting coil, a spiral groove is formed on the outer peripheral surface side of a cylindrical winding frame made of an electrically insulating material, and a superconducting wire is wound along the groove. Wound and bind the tape for force support, and in the cylindrical axis direction on the outer peripheral surface side of the cylindrical reel, shall have a plurality of cooling ducts,
Furthermore, an insulating cylinder made of an electrically insulating material is formed between the low-voltage winding and the high-voltage winding in the concentric cylindrical shape with a predetermined gap between the outer peripheral surface of the low-voltage winding and the inner peripheral surface of the high-voltage winding. A superconducting transformer, which is provided. 2. The superconducting transformer according to claim 1, wherein the tape for supporting the electromagnetic force is a semi-cured resin-impregnated glass bind tape. 2. The superconducting transformer according to claim 1, wherein said tape for supporting electromagnetic force is a metal tape of a normal conductor. The superconducting transformer according to any one of claims 1 to 3, wherein the insulating cylinder is made of FRP mainly composed of epoxy resin and glass fiber. 5. The superconducting transformer according to claim 4, wherein the insulating cylinder is formed by winding a semi-cured epoxy glass prepreg sheet a plurality of times and curing the same. 6. 5. The superconducting transformer according to claim 4, wherein the insulating cylinder is formed by winding a thin insulating sheet of the FRP a plurality of times, applying an epoxy resin, and performing a curing treatment. Transformer.

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