JP2883071B1 - Superconducting field winding conductor - Google Patents

Abstract

The present invention provides a superconducting conductor structure capable of completely stabilizing a superconducting field winding in a rotor of a superconducting generator with a high conductor current density. A superconducting element wire having a three-layer structure is formed into a primary stranded superconducting conductor and arranged at the center of a superconducting composite conductor, and a copper-nickel alloy surrounding an aluminum stabilizer is used as a primary stranded superconducting conductor. , And these are integrally surrounded by a thin plate 1 of copper or copper alloy, and the internal structures are joined with solder 5 to minimize thermal resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a structure of a conductor used for a field winding of a superconducting generator having a superconducting field winding on a rotor. In particular, liquid helium has a supercritical pressure in a high-speed rotating rotor, and its cooling capacity is about 10 times that in a static gravitational field. A completely stabilized field winding utilizing its high cooling capacity The present invention relates to a conductor structure of a wire.

[0002]

2. Description of the Related Art A superconducting field winding of a superconducting generator includes one for partial stabilization and one for complete stabilization. In the case of partial stabilization, a coil configuration resistant to disturbance is employed by impregnating the coil. Also, the conductor used for this has a configuration of a primary stranded wire or a secondary stranded wire.
On the other hand, the structure aiming for complete stabilization also employs a primary stranded wire or a secondary stranded wire.

[0003] The generator is connected to an external power transmission system, and is in an environment where there is much disturbance such as a system accident, and the field winding is required to have a small AC loss. Reflecting this, the conductor used for the field winding of the superconducting generator is 50 kW / m
Those with less than 3 AC losses were used.

[0004]

In the above prior art, which aims at complete stabilization, a conductor having a structure with a small AC loss has a large temperature gradient inside when the conductor is partially made normal in the longitudinal direction. There is a problem that the cooling ability is inevitably increased, which is inevitable.

SUMMARY OF THE INVENTION An object of the present invention is to provide a structure for maintaining a cooling capacity of a conductor used for a field winding of a superconducting generator, and to provide a conductor structure for preventing deformation due to a higher centrifugal force. It is in.

[0006]

In order to solve the above-mentioned problems, in the present invention, a main stabilizing material which is a heat-generating portion after a normal-conductivity transition is arranged in a portion close to a cooling surface, and a material for the stabilizing material is used. Around 4.2K, aluminum having a lower specific resistance than copper is used, a portion of the superconducting wire through which the superconducting current flows is arranged at the center of the conductor, and these are integrated from the periphery using a thin plate made of copper or a copper alloy to form a conductor. The interior is filled with solder to improve heat transfer performance.

Further, by using an appropriate amount of the aluminum stabilizing material or using a high-resistance copper alloy for the thin plate, it is possible to suppress an increase in AC loss within an appropriate range. By adopting such a conductor structure, the temperature gradient inside the conductor can be sufficiently reduced at the time of normal conduction transition, and the superconducting field winding can be completely stabilized without lowering the cooling capacity.

[0008] Further, by forming a part of the matrix of the superconducting wires constituting the primary stranded superconducting conductor by a copper-nickel alloy or by using a copper alloy thin plate having excellent mechanical strength, the whole of the formed superconducting composite conductor is improved. And the deformation due to centrifugal force can be prevented.

[0009] With the above structure, the temperature gradient inside the conductor can be sufficiently increased because aluminum, which is a heat generating part at the time of normal conduction transition, is close to the cooling surface and the thermal conductivity of aluminum is very high. The cooling capacity of the superconducting conductor can be improved, and the superconducting generator can achieve complete stabilization in the operating current range of the superconducting field winding in the rotor. In addition, deformation due to centrifugal force can be prevented by high strength.

[0010]

FIG. 1 is a cross-sectional view of a conductor for a superconducting field winding according to an embodiment of the present invention. The superconducting field winding of the superconducting generator is a two-pole or four-pole superconducting winding. The field winding of the superconducting generator is provided on a rotor that rotates at a high speed.
An acceleration of 0G is acting. In such a high acceleration field, liquid helium generally has a supercritical pressure, and its cooling characteristic is about ten times that in a 1G gravitational field.

When the superconducting winding using NbTi is provided with an operating current density of 40 to 50 A / mm2 in a gravitational field of 1 G to achieve high stability of the conductor, a partial normal conduction of the superconducting winding is achieved. Even when the transition occurs, the cooling characteristic exceeds the heat generation characteristic of the conductor, and a so-called perfect stabilization design that returns to the superconducting state is possible. In a high acceleration field of 4000 to 5000 G, the cooling capacity becomes about 10 times, so that the current density is (40 to 50) × √10 = 132 to 165 A / mm 2
Even at a current density of, a completely stable design can be achieved. The outer diameter of the rotor of the generator is limited by centrifugal force and its length is limited by vibration characteristics.
If a current density of about / mm2 cannot be secured, the function as an economical generator cannot be sufficiently achieved.

If the liquid helium is cooled in a high centrifugal force field and complete stabilization is achieved, it can be achieved at about 150 A / mm 2, and a superconducting generator having a sufficiently economical size can be manufactured.

When the superconducting field winding of the superconducting generator is completely stabilized, even if buds of normal conduction due to some heat generation occur within a predetermined current range, the buds are reduced and disappear, and no quench occurs. It is important that a superconducting generator as a power device requiring reliability can completely avoid the danger of quench.

The conductor used for the completely stabilized superconducting field winding of the superconducting generator described above has the configuration shown in FIG.

In the superconducting field winding, both sides parallel to the radius of the conductor constituting the winding are 30 to 70% of the longitudinal direction of the conductor.
In the structure where is cooled, the following conductor structure is adopted.

The superconducting filament is stabilized by copper, and has a number of units surrounded by a copper-nickel alloy.
The superconducting element wire 4 having a three-layer structure is converted into a primary stranded superconducting conductor and arranged at the center of the formed superconducting composite conductor. The aluminum stabilizer 3 is coated with the copper-nickel alloy 2 and arranged on both sides of the primary stranded superconducting conductor. The primary stranded superconducting conductor and the aluminum stabilizing material 3 covered with the copper-nickel alloy 2 on both sides are integrated around the periphery thereof by a thin plate 1 of copper or a copper alloy. Further, the space between the integrated internal structures is filled with solder 5 to minimize thermal resistance.

FIG. 2 shows another example of a conductor for a superconducting field winding. The copper or copper alloy thin plate 1 is wrapped around so as to cover the formed superconducting composite conductor, but has a structure in which a gap 6 is opened instead of a tube, and the gap is arranged near the center corresponding to the superconducting element wire 4.

FIG. 3 shows an example of another conductor for a superconducting field winding. In the thin plate 1 made of copper or copper alloy, a through hole 7 penetrating the thickness is formed so as to have an average distribution density.

It has been experimentally confirmed that the superconducting field winding of the superconducting generator has a cooling characteristic as shown in FIG. When the conductor is completely stabilized in accordance with Maddock's theory of complete stabilization, a maximum heat flux of about 30 kW / m ₂ can be obtained, but the cooling characteristic takes into account the characteristic variation of ± 25% with respect to the value shown in FIG. Should. Therefore, in the conductor of the present invention, the thermal load on the cooling surface 8 is set to 20 kW / m ₂ or less when a normal current is transferred when a predetermined current is applied so that the lower limit characteristics can be completely stabilized. To

When ordinary low-speed excitation is performed in the superconducting field winding of the superconducting generator, the magnetic field changes by about 5 T / s. At that time, the AC loss of the conductor of the present invention is 200 to 50.
It is assumed that it is 0 kW / m ₃ . Since the heat generated by the normal conductive transition at a predetermined exciting current is 2000~3000kW / m _3, AC loss 200~500kW / m ₃ is not a problem. 50k if AC loss is reduced using current technology
W / m ₃ or less, but a large internal temperature difference due to thermal resistance at the time of normal conduction transition generated in such a case hinders achievement of complete stabilization, but AC loss is reduced to 200 to 500.
By allowing up to kW / m _3, the use of poorly conductive metal can be reduced and the thermal resistance can be reduced sufficiently.

The conductors of the superconducting field winding are wound in an edgewise manner or a flatwise manner. In the above description, the conductor configuration suitable for the edgewise manner is shown. Although the above-described configuration is possible in the case of flat wise, the following configuration can also be used.

FIG. 5 shows another example of a conductor for a superconducting field winding. The superconducting filament is stabilized by copper, and the periphery of the superconducting filament has a large number of units surrounded by a copper-nickel alloy. And placed on the opposite side.

FIG. 6 shows another example of a conductor for a superconducting field winding. The copper or copper alloy thin plate 1 is wrapped around so as to cover the formed superconducting composite conductor, but has a structure in which a gap 6 is opened instead of a tube, and the gap is arranged near the center of a surface other than the cooling surface 8.

FIG. 7 shows an example of another conductor for a superconducting field winding. In a thin plate made of copper or a copper alloy, through holes 7 penetrating the thickness are formed so as to have an average distribution density.

As described above, according to the present invention, the heat generated when the superconducting conductor undergoes a normal-conductivity transition utilizes the low electric resistance of the aluminum stabilizing material at a very low temperature and the large thermal conductivity, thereby reducing the heat generated in the rotating field. Since the cooling can be effectively performed by the large heat transfer coefficient of the critical pressure helium, the conductor current density is 13
The superconducting field winding of _{2 to} 165 A / mm ₂ can be completely stabilized.

[0026]

The primary stranded superconducting conductor is placed at the center of the conductor, an aluminum stabilizing material is placed near the cooling surface on the side surface, and they are integrated with a copper or copper alloy thin plate, and the inside is soldered. By filling, a conductor for a superconducting field winding that has a small temperature gradient and excellent cooling effect when internal heat is generated and that can be completely stabilized can be obtained.

Also, the primary stranded superconducting conductor is placed at one end of the cross section of the conductor, an aluminum stabilizer is placed near the cooling surface at the other end, and they are integrated with a copper or copper alloy thin plate to form an interior. May be filled with solder.

By cutting out a part of the copper or copper alloy thin plate surrounding the inside of the conductor, it is possible to continuously manufacture a molded conductor so as to surround the internal structure of the conductor during the production of the conductor.

By providing the through-holes in the thin plate so as to be distributed evenly, the bending rigidity of the formed conductor can be reduced, and the winding process is facilitated.

The current density during operation of the conductor is 132 to 165.
A / mm _2, and by setting the heat load on the cooling surface at the time of normal conduction transition to 20 kW / mm ₂ or less, the field winding placed in the rotor of the superconducting generator can be completely stabilized. .

The field winding conductor is driven in a fluctuating magnetic field of 5 T / s.
By allowing an AC loss characteristic of 00 to 500 kW / m ₃ , the heat resistance inside the conductor can be reduced, and a conductor configuration that can be completely stabilized becomes possible.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a conductor for a superconducting field winding according to an embodiment of the present invention.

FIG. 2 is a sectional view of a superconducting field winding conductor according to another embodiment of the present invention.

FIG. 3 is a perspective view of a superconducting field winding conductor according to another embodiment of the present invention.

FIG. 4 is a diagram showing cooling characteristics in a superconducting field winding of the present invention.

FIG. 5 is a cross-sectional view of a superconducting field winding conductor according to another embodiment of the present invention.

FIG. 6 is a sectional view of a superconducting field winding conductor according to another embodiment of the present invention.

FIG. 7 is a perspective view of a superconducting field winding conductor according to another embodiment of the present invention.

[Explanation of symbols]

1: thin copper or copper alloy sheet, 2: copper-nickel alloy, 3
... Aluminum stabilizer, 4 ... Three-layer superconducting wire,
5 solder, 6 gap, 7 through hole, 8 cooling surface.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01F 6/06 H01B 12/02

Claims (6)

(57) [Claims] 1. A molded superconducting composite having a rectangular cross section, in which copper and aluminum for stabilizing a superconducting filament, a part of a conductor matrix are composed of a copper-nickel alloy, and two opposite sides are cooled by liquid helium or supercritical helium. In a superconducting field winding conductor using a conductor, a primary stranded superconducting conductor obtained by twisting a superconducting element wire containing a copper-nickel alloy in a matrix is disposed at the center of the molded superconducting composite conductor, An aluminum stabilizing material coated with a copper-nickel alloy is arranged on both sides near the cooling surface of the conductor, and the primary stranded superconducting conductor and the aluminum stabilizing material are integrated by a thin plate made of copper or a copper alloy,
A conductor for a superconducting field winding, wherein the primary stranded superconducting conductor and an aluminum stabilizing material are joined by soldering the surfaces of the thin plates that are in contact with each other. 2. A molded superconducting composite having a rectangular cross section in which copper and aluminum for stabilizing a superconducting filament and a part of a conductor matrix are composed of a copper-nickel alloy and two opposite sides are cooled by liquid helium or supercritical helium. In a superconducting field winding conductor using a conductor, a primary stranded superconducting conductor obtained by twisting a superconducting element wire is arranged near a surface opposite to a cooling surface of the molded superconducting composite conductor, and the molded superconducting composite is formed. An aluminum stabilizer coated with a copper-nickel alloy is disposed on a side of the conductor near the cooling surface, and the primary stranded superconducting conductor and the aluminum stabilizer are integrated with a thin plate made of copper or a copper alloy, A conductor for a superconducting field winding, wherein a surface of a primary stranded superconducting conductor, an aluminum stabilizer, and the thin plate that are in contact with each other are joined by soldering. 3. The copper or copper alloy thin plate has a length of the formed superconducting composite conductor in a longitudinal direction, and in a cross section of the formed superconducting composite conductor, makes a round so as to cover the formed superconducting composite conductor, but is not cooled. 3. The conductor for a superconducting field winding according to claim 1, wherein an end in a circumferential direction is in contact with a gap at a center of the surface. 4. The thin plate of copper or copper alloy has through holes in the thickness direction having an average distribution.
Or the conductor for superconducting field winding according to 2. 5. The molded superconducting composite conductor in the operating current range has a current density of 132 to 165 A / mm 2, and the heat flux due to the heat generated during normal-conductivity transition in liquid helium or supercritical helium, 3. The superconducting field winding conductor according to claim 1, wherein the cooling surface of the formed superconducting composite conductor is 20 kW / m2 or less. 6. The conductor for a superconducting field winding according to claim 1, wherein the molded superconducting composite conductor has an AC loss characteristic of 200 to 500 kW / m3 in a fluctuating magnetic field of 5 T / s.