KR100521573B1 - Bobbin for superconductive magnet - Google Patents

Abstract

The present invention relates to a bobbin for a superconducting electromagnet of the conduction cooling method of conducting cooling using a cooler, particularly GM (Gifford-McMahon) cooler, the superconducting bobbin according to the present invention is cut off at regular intervals on the outer peripheral surface layer FRP coating layer is formed to form a spiral winding groove is formed, each layer of the spiral winding groove is formed by winding the plate wire to fill the winding groove first and then divided into a vertical winding layer to form a double winding layer, Spacers are interposed between the plate wires and each of the double winding layers. Preferably, each of the spiral winding grooves forming the bobbin layer is separated from each other, and each bobbin layer is a coupling hole formed perpendicularly to the bobbin layer. It is preferable that the bolt and nut are inserted into each other. Each of them is divided to form a number of pieces, but each source is preferably joined to each other. Such multi-layered or circular pieces of bobbins facilitate handling of heavy bobbins to facilitate transport and winding, and to facilitate correction / completion of superconducting magnet errors that may occur during assembly and operation.

Description

Bobbin for superconducting magnets {BOBBIN FOR SUPERCONDUCTIVE MAGNET}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to bobbins for superconducting electromagnets of the conduction cooling method that are conduction-cooled using a cryocooler, particularly GM (Gifford-McMahon) cooler. FRP coating layer is formed to form a spiral winding groove is formed, and the winding wire is facilitated by winding the plate in a double pancake (double pancake) method based on each winding groove layer.

In 1911, Dutch scientist Onnes (HK, 1853–1926) found that mercury was cooled with liquid helium and the resistance disappeared at -269 ° C (4K), slightly above absolute zero (-273 ° C). This was called the 'superconducting state'. Since then, many scientists have continued their research, thinking that if you can make an electromagnet with superconducting properties, you can make an electromagnet with no power loss.

In general, the superconducting field is classified into a low temperature superconducting field of 30K or less and a high temperature superconducting field of 30K or more based on 30K. Most of the superconducting materials currently used are so-called low-temperature superconductors having a critical temperature (T _c ) of 30K or less, and Nb-Ti alloys are mainstream, and Nb ₃ Sn is partially used. These low-temperature superconductors are used for various applications as ultra-high sensitivity magnetic sensors or superconducting electromagnets for generating high magnetic fields. However, related to the electric power field, superconducting magnetic energy storage systems (SMES) convert electricity into magnetic energy and store it. This is unique.

The biggest constraint that these low temperature superconductors have not been applied more widely in the power sector, except for SMES, is that they are not economical because T _c is so low that expensive liquid helium must be used as a cooling medium in the operation of the application. Possibilities to overcome the limitations of the application such as low-temperature superconducting material is from the series of T _c is found, a high-temperature superconducting material than 30K after 1986.

In 2001, as the frontier business of the Ministry of Science and Technology, the next generation of superconducting application technology development project has begun, and the research and development of superconducting wires and application devices for the application of electric power field is in progress. Applications in the power sector are expected to include superconducting cables, superconducting transformers, superconducting fault current limiters, and superconducting motors.

Double fault current limiter is a kind of circuit breaker installed to prevent damage to various power devices installed in the system due to abnormal voltage or current flowed into the power system due to lightning or short circuit. Conventional current limiters cause power outages by completely shutting off electricity, but superconducting current limiters use the characteristics of superconductivity to transform high fault currents into normal conditions, thus protecting the system without a power outage in the event of an accident. Appliance. These superconducting fault current limiters can be used for protection of transmission and distribution facilities in addition to system stabilization birds, so the demand is enormous. The developed countries have already successfully developed 15kV small capacity superconducting fault current limiters, and are currently developing 100-300 MVA class high capacity superconducting fault current limiters. Research is ongoing. The core technologies of the superconducting fault current limiter are large capacity superconducting coil manufacturing technology, coil protection technology, large capacity power electronic circuit technology, power system application and operation technology, and cryostat technology for superconducting current limiter.

The present invention relates to a superconducting technology> high temperature superconducting technology> high temperature superconducting magnet> to bobbins for the same, and to the coil protection technology and the low temperature holding device technology in the above-mentioned core technical problem.

The present invention relates to a bobbin for a high temperature superconducting magnet that can be used in a power device such as a high temperature superconducting fault current limiter as described above,

First, to provide a coating layer that can achieve durability at about 20K under vacuum while achieving reliable insulation on the highly conductive copper bobbin body,

Secondly, providing a means for ease of winding to said coating layer;

Third, to separate the bobbin into a multi-layer to facilitate error correction / supplementation of superconducting magnets,

Fourth, to divide the bobbin again to obtain the stability of operation and to prevent the appearance deformation,

Fifth, the purpose is to ensure the thermal stability, durability and operational stability of the DC reactor, and furthermore the current limiter through the above means.

In order to achieve the above object, the superconducting magnet bobbin according to the present invention is coated with an FRP coating layer having spiral winding grooves formed on the outer circumferential surface at a predetermined interval to form a layer, and each wire of the spiral winding groove has a plate wire first. After winding to fill the winding groove, the coil is divided into upper and lower portions to form a double winding layer, and spacers are interposed between the panel wires constituting the double winding layer and between each of the double winding layers.

Preferably, each spiral winding groove constituting the bobbin layer is to be separated from each other, each bobbin layer is preferably to be coupled by a bolt and a nut inserted into the coupling hole formed perpendicular to the bobbin layer.

More preferably, the bobbin is divided so as to form a plurality of powder pieces in each bobbin layer, but each powder material is preferably joined to each other.

In addition, the bobbin may be formed by interposing an indium thin plate to increase the contact area of each bobbin layer.

Hereinafter, described in detail by the accompanying drawings of the present invention.

FIG. 1 is a schematic view of a DC reactor for a current limiter in which a bobbin for a superconducting magnet according to the present invention may be used, and the head 11 of the GM cooler 10 is exposed to an upper portion of the DC reactor housing 1. The inside of the housing 1 is in a vacuum state. This GM cooler has been developed recently, and can be cooled to 4K or less, so that it can conduct a superconducting state by directly conducting and cooling the bobbin of the electromagnet without using a refrigerant. GM cooler 10 is composed of two stages, the upper cooling unit 13 and the lower cooling unit 15 contained in the housing (1). The GM cooler 10 is supported by the housing 1 top plate at the head 11, and is supported by the vertical support rods 5a and the horizontal support rods 3a at the ends of the upper cooling units 13. The sealed support type is to make the contact area with the cooler 10 as small as possible, and synthetic resin having low thermal conductivity is used. The superconducting magnet 30 is positioned below the lower cooling part 15 of the GM cooler 10 and is also supported by the horizontal supporting rods 3b and the vertical supporting rods 5b and 5c. The rods 3a, 3b (5a, 5b, 5c) are connected to each other. The superconducting magnet 30 is connected to the lower cooling unit 15 by a plurality of cooling rods 29 so as to be electrically cooled through the lower cooling unit 15 of the cooler 10. The cooling rod 29 or the material of the cooler 10 may be a material such as oxygen-free copper (OFC), tough pitch copper, aluminum having excellent thermal conductivity, but oxygen-free copper is most preferred. . The electric wire for applying current to the superconducting magnet 30 is wrapped in the bushing 27 in the upper part of the housing 1 for airtightness and is connected to the magnet 30. In addition, the wire is roughly divided into the housing 1 and the outside, and is divided into the metal wire 23 above the bushing 27, and the one contained in the housing 1 is divided into a high temperature superconductor (HTS) wire 25. . In particular, the metal wires 23 are cooled in the upper cooling part 13 and / or the lower cooling part 15 of the cooler 10 for conduction cooling until the portion included in the housing 1 is HTS wire 25. A copper foil plate is stacked to be electrically cooled through a thermal link 20 connected to one of the rods 29. In this way, it is possible to prevent the superconducting state of the superconducting magnet 30 from being quenched by conduction cooling of the metal wire 23 through which a high current flows.

As such, the detailed structure of the bobbin for the superconducting magnet 30 that can be used in the DC reactor shown in FIG. 1 may be well understood with reference to FIG. 2A and below. First, in FIGS. 2A and 2B showing a perspective view and a partial cross-sectional view of a bobbin according to the first aspect of the present invention, the bobbin 40 is covered with an FRP coating layer 41 on its outer circumferential surface. The FRP coating layer 41 covers not only the body 40a of the bobbin but also the inside of the upper and lower flange portions 40b and 40c. The body 40a of the bobbin is also preferably of an oxygen-free copper material for thermal conductivity. FRP is used because it can maintain its original form and properties even under extreme conditions. Glass fiber (GFRP), carbon fiber (CFRP), boron fiber, aramid fiber And the like.

The FRP coating layer 41 is formed with a spiral winding groove 41a which is cut at regular intervals to form a layer. The number of winding grooves 41a constituting this layer is variable as necessary, and its width and depth are determined depending on the width and thickness of the plate wire to be wound on the bobbin 40. For example, the high temperature superconducting wire (Wire Type PN0002831) of ASC (American SuperConductor), which is a plate wire that can be used in the present invention, has a thickness of 0.4 mm and a width of 4.1 mm. The width and depth of the grooves 41a formed in the coating layer 41 are determined in accordance with this electric wire. As a result, the width of the winding groove 41a is enough to accommodate a single wire, and the depth is sufficient to secure insulation through the FRP coating 41. For example, when the thickness of the coating 41 is 2 mm, the wire is It is good to have a depth of 0.4 mm which is about once wound. However, the depth of this groove 41a is variable depending on the thickness of the coating and the thickness of the board.

3A, 3B, 3C, and 3D are exploded perspective views of the bobbin according to the second aspect of the present invention, a partial cross-sectional view of the bobbin layer, a wound bobbin layer perspective view, and a wound bobbin layer partial cross-sectional view, respectively, FIGS. 2A and 2B. The difference from the bobbin 40 according to the first feature is that the bobbin 140 has a separate structure for each spiral winding groove 141a that forms a layer. This separation structure is intended to facilitate the ease of correction and correction of errors that may occur during assembly or operation of the superconducting magnet. Each bobbin layer 140a is coupled with a bolt B and a nut inserted into the coupling hole H vertically formed. This coupling is also possible by means of bolt / nut structures (not shown) which may alternatively be formed for each layer. In each of the bobbin layers 140a, an indium thin plate I may be interposed to increase the contact area. The indium thin plate (I) may cover the entire upper surface of each bobbin layer (140a), and may be located in several places as shown in FIG. 3c, and have high thermal conductivity and ductility of the metal (eg, lead and aluminum) to improve thermal contact. Can be substituted.

In addition, the structure of the bobbin 140 separated into a plurality of layers is to solve the problem that the material is not easy to handle in the case of the integral bobbin 40 of Figure 2a because the weight of the bobbin is the same. Of course, if the bobbin of the desired height is separated into multiple layers, the winding of the wire rod will be easy and easy to transport. As shown in FIGS. 3C and 3D, the wire wound on the bobbin of the present invention is in the form of the above-described plate wire, and the plate wire W is an FRP coating layer of each bobbin layer 140a at about the middle of the length to be wound. (141) First, the winding is wound in the spiral winding groove 141a formed on the outer circumferential surface of the winding groove 141a, and both ends thereof are divided up and down to form a double winding layer 143 having a predetermined thickness. However, the spacers S1 and S2 are interposed between the plate wires W constituting the double winding layer 143 and between the double winding layers 143. In particular, it is preferable that the spacer S1 interposed between the plate wires W among the spacers is cut and is easily fitted between the upper and lower winding layers. This winding method is called a 'double cake' (double cake) method. The spacers S1 and S2 may be thin sheets of FRP material. As a result, the height of one bobbin layer 140a is equal to the sum of the widths of the two wires W and the thickness of the two spacers S1 and S2. This double pancake winding also applies to the first feature bobbin 40 shown in FIGS. 2A and 2B and the third feature bobbin 240 of the present invention to be described with reference to FIG. 4. That is, in the bobbin 40 of FIG. 2a, the winding groove 41a of the first layer is also wound to fill the winding groove 41a first, and then divided up and down to form a double winding layer. Then, the spacers S1 and S2 are interposed between the panel wires W constituting the double winding layer and between the double winding layers.

Next, in FIG. 4, which is an exploded perspective view of the bobbin according to the third aspect of the present invention, the difference from the bobbin 140 shown in FIGS. 3A-3D is that each layer 240a of the bobbin 240 is divided into a plurality of 'divided' sections. It is said to be a piece of hollow circumferential layer (hereinafter referred to as a 'circular piece') (P). In FIG. 4, the quadrants are shown, but two, six, eight, or more may be used. Each powder piece P is bonded to each other by a bonding polymer such as epoxy resin or silicone. The bobbin layer 240a having the above-described circular element P structure is to prevent a decrease in inductance due to Eddy Current Loss that may be generated when a current is changed. When a conductor is placed in an alternating alternating magnetic field, the current generated in the conductor becomes a eddy current due to electromagnetic induction, which is called eddy current. This eddy current induces electromotive force in the secondary winding of the transformer. It is a loss. In addition to the eddy current loss, the bonded powder pieces P have some fluidity to each other, thereby minimizing the deformation of the bobbin 240 due to the difference in thermal shrinkage between the bobbin body of the copper material and the coating layer of the FRP material. This is to prevent heat leakage due to a gap that may occur between the two components. In addition, the winding method of the plate wire wound on the outer circumferential surface of the bobbin 240 is made of a double pancake method as described above. In addition, the indium thin plate I may be interposed in each of the bobbin layers 240a to increase the contact area.

Referring to the operation and effect of the superconducting bobbin of the present invention described above are as follows.

In order to operate the conduction cooling superconducting electromagnet 30, first, a vacuum environment inside the DC reactor housing 10 is created. Then, the GM refrigerator 10 is operated. Then, the superconducting electromagnet connected to the refrigerator is cooled to about 20K. At this time, the wire (W) wound on the bobbin is lowered to a temperature below the critical temperature (120K) is a superconducting state. In this superconducting state, since the electrical resistance is zero, the magnet can be operated without loss while the current below the threshold current is energized.

Conventional bobbins are made of an insulating material such as FRP, but in the case of conductive cooling, a bobbin of a conductive material such as copper is required. In order to be used in power equipment such as a current limiter, care must be taken to insulate at high voltages. Therefore, an insulation problem is solved by placing an FRP coating layer on a copper bobbin.

As described above, the superconducting magnet bobbin according to the present invention

First, the FRP coating layer is formed on the outer surface of the bobbin body made of copper, which has good conductivity, to achieve reliable insulation and maintain durability at about 20K under vacuum.

Second, a spiral winding groove is formed in the coating layer and the winding groove forms a layer to facilitate a double pancake winding.

Third, the bobbin is divided into multiple layers or back into multiple pieces to facilitate handling of heavy bobbins to facilitate transportation and winding, and to facilitate correction / completion of superconducting magnet errors that may occur during assembly and operation. ,

Fourth, because the bobbin layer is used as a structure that combines the source piece to prevent the eddy current loss, to obtain the stability of the operation and to prevent the appearance deformation,

Fifth, through the above means, the thermal stability, durability, and operational stability of power devices such as direct current reactors and even current limiters were guaranteed.

1 is a schematic diagram of a DC reactor using a superconducting magnet bobbin according to the present invention;

2a and 2b are a perspective view and a partial cross-sectional view of the bobbin according to the first aspect of the present invention;

3A, 3B, 3C and 3D are exploded perspective views of a bobbin according to a second aspect of the present invention, a partial cross-sectional view of the bobbin layer, a wound bobbin layer perspective view and a wound bobbin layer partial cross section view,

4 is an exploded perspective view of a bobbin according to a third aspect of the present invention.

<Description of Symbols for Major Parts of Drawings>

1: DC reactor housing 3a, 3b, 5a, 5b, 5c: support rod

10: GM cooler 11: head

13: Upper cooling part 15: Lower cooling part

20: thermal link 21a, 21b: pressing plate

23: metal wire 25: HTS wire

27: bushing 30: superconducting magnet

40,140,240: Bobbin 40a, 140a, 240a: Bobbin Body

40b, 140b, 240b, 40c, 140c, 240c: flange 41,141: FRP coating layer

41a, 141a, 241a: winding groove 143: double winding layer

W: plate wire S1, S2: spacer

P: Division

Claims (5)

The FRP coating layer 41 is formed on the outer circumferential surface of the spiral winding groove 41a, which is cut off at a predetermined interval to form a layer, and each plate of the spiral winding groove 41a has a plate wire W first wound groove 41a. ) Is wound to fill and then divided into upper and lower to form a double winding layer, superconducting spacers (S1) (S2) are interposed between the panel wire (W) and the double winding layer constituting the double winding layer. Bobbins for magnets. The method of claim 1 wherein the bobbin is Each spiral winding groove 141a forming a layer is to be separated, respectively, each bobbin layer is coupled to the superconducting magnet, characterized in that coupled to the bolt and nut inserted into the coupling hole (H) formed perpendicular to the bobbin layer Dragon bobbin. The method of claim 2 wherein the bobbin is A bobbin for a superconducting magnet, wherein each bobbin layer is divided so as to form a plurality of minute pieces P, and each minute piece P is joined to each other. The method according to any one of claims 1 to 3, The superconducting magnet bobbin, characterized in that the spacer (S1) interposed between the plate wire (W) constituting the double winding layer is cut. 4. The bobbin of claim 2 or 3, wherein the bobbin is A superconducting magnet bobbin, characterized in that the indium plate (I) is interposed to increase the contact area for each bobbin layer.