JPH10107332A - Permanent current switch - Google Patents

Abstract

(57) [Problem] To provide a magnetic field type permanent current switch having a non-inductive coil which is robust, has high reliability, and is small and easy to manufacture. SOLUTION: Permanent current switch coil bobbin 11
A folded member 14 is provided on one end surface 13 of the bobbin, and each of the folded members 14 is inscribed on the outer periphery of the bobbin on one diameter of the bobbin 11 and has an outer diameter d smaller than １ ／ of the outer diameter D of the bobbin. The coil conductor 12 for the permanent current switch is composed of two cylindrical projections 14a and 14b.
The conductors 12 are folded back and wound in an S-shape along the outer periphery of the projections 14a and 14b, and extend from both sides of the folded back.
a and 12b are spirally wound in parallel on the peripheral surface of the bobbin 11 in the same direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic field type permanent current switch having a non-inductive coil.

[0002]

2. Description of the Related Art A permanent current switch is an indispensable element for realizing a permanent current circuit in combination with a superconducting coil, and includes a superconducting magnetic energy storage device (SMES),
Applications to magnetic levitation railways, superconducting magnets for physics and chemistry experiments, etc. are being promoted. This permanent current switch is formed of a conductor that can transition between a superconducting state and a normal conducting state in any direction by setting environmental conditions, and when the conductor is in the superconducting state, the electric resistance is changed. Since the current becomes zero, the current is conducted without attenuation and the switch is turned on, and when the conductor is changed to the normal conducting state, the electric resistance is increased and the switch is substantially turned off. ing.

For example, in a superconducting magnetic energy storage device whose operation is shown in FIGS. 6 to 8, a permanent current switch is used as follows. In this superconducting magnetic energy storage device, the superconducting coil 1 and the permanent current switch 2 are connected in parallel, and this parallel circuit is connected to an AC / DC converter 5 via a power lead wire 3 and an open / close switch 4. The device 5 is further connected to an AC power supply system (not shown). Each of the superconducting coil 1 and the permanent current switch 2 is formed of a superconducting conductor that transitions to a superconducting state at a low temperature, and the entire parallel circuit is cooled by a coolant such as liquid helium.

Now, in order to store electric power using this superconducting energy storage device, first, as shown in FIG. 6, the on / off switch 4 is closed and the permanent current switch 2 is brought into a normal conduction state by switching the switch. In the off state, a DC current is supplied to the superconducting coil 1, and the electric power is stored in the superconducting coil 1 as electromagnetic energy.

Next, after the permanent current switch 2 is turned on by bringing the permanent current switch 2 into a superconducting state with the open / close switch 4 closed, the current flows into the permanent current switch 2 when the external current is reduced. When the DC current from the outside becomes zero, a current equivalent to the current flowing through the superconducting coil 1 flows through the permanent current switch 2, and a permanent current mode is set. In this state, the open / close switch 4 is opened as shown in FIG. Then, since the electric resistance of both the superconducting coil 1 and the permanent current switch 2 is zero, the current continues to flow in this closed circuit without being attenuated as a permanent current, and the energy stored in the superconducting coil 1 is lost. Will be stored at

In order to take out the stored energy, as shown in FIG. 8, the permanent current switch 2 is turned off by bringing the permanent current switch 2 into a normal conduction state after closing the open / close switch 4. Then, the energy stored in the closed circuit can be extracted as electric power through the power lead wire 3.

In the permanent current switch 2 described above, switching is performed by a transition between a superconducting state and a normal conducting state. Therefore, it is important to perform this transition stably with good reproducibility and at high speed. Becomes By the way, it is known that this transition is caused by any one of the temperature, the magnetic field, the electric current, and the mutual condition change.
That is, each of these three conditions has a critical value, and the conductor enters a superconducting state or a normal conducting state at least one of the critical values.

Conventionally, as a switching method of a permanent current switch, a thermal method of changing a temperature is most generally used. In the thermal method, a superconducting conductor (hereinafter simply referred to as a “conductor”), which is a conductor for a switch, and a heater wire for temperature control are wound together in a coil shape, and usually a heat insulation structure is impregnated with epoxy resin. Many. A superconducting wire mainly made of an Nb-Ti alloy is used as a conductor for the winding used for this, and its critical temperature is about 9K. Therefore, this conductor transitions between the superconducting state and the normal conducting state at about 9K.

When the permanent current switch is operated, the switch is turned off when the heater wire is energized and the superconducting wire is heated to about 9K or more, and the heater wire is de-energized and the conductor is heated to about 9K or less by surrounding helium. The switch is turned on when it cools down. Therefore, switching can be performed by repeatedly lowering / raising the temperature of the conductor across about 9K.

[0010] However, this thermal type device has a problem that it takes several seconds to several tens of seconds to respond particularly to switching of a large current because the temperature control system has a heat capacity or takes a long time to conduct heat. is there. Also, with this structure, a heat insulation structure with poor heat dissipation must be used to raise the temperature of the conductor, so when turned off, the conductor may suddenly generate heat and be cut off. There was also.

On the other hand, a magnetic field type permanent current switch utilizes the property that when a magnetic field is applied to a superconducting conductor from the outside in a low temperature range, a transition between a superconducting state and a normal conducting state occurs at a critical magnetic field strength. It is. Therefore, this magnetic field type permanent current switch is composed of a superconducting coil for switching (hereinafter simply referred to as "coil") and an electromagnet for generating a control magnetic field. In practice, the superconducting magnet for controlling the magnetic field is often arranged coaxially around the outer periphery of the coil. As the conductor of the coil, a superconducting material having an appropriate critical magnetic field strength that can easily control the magnetic field is used. For example, a Cu-Nb alloy having a critical magnetic field strength of about 1 T (tesla) or less is generally used.

In this magnetic field type permanent current switch, it is not necessary to raise the temperature of the conductor in principle, so that a coil structure with good heat dissipation becomes possible, and the conductor and the coil are effectively cooled. The conductor temperature rise due to the heat generated by the AC heat loss of the conductor generated when the external magnetic field intensity is varied is relatively small, and there is an advantage that stable and high-speed switching is possible as compared with the thermal type.

The magnetic field type permanent current switch is usually used in combination with a coil and a control superconducting magnet as described above. Therefore, in order to minimize the induced voltage induced in the coil due to the magnetic field fluctuation accompanying the excitation and demagnetization of the superconducting magnet, the coil has a so-called "non-induction winding" structure. This non-inductive winding is realized by winding a conductor on a bobbin such that an opposite current flows through an adjacent conductor. A coil having a non-induction winding structure (hereinafter, referred to as a “non-induction coil”) has an advantage of suppressing generation of an induced voltage by extremely reducing the self-inductance of the coil itself.

The non-inductive winding of the permanent current switch coil is conventionally performed as follows. That is, as shown in FIG. 9, a cylindrical return guide 32 whose axis is orthogonal to this is provided in advance on the peripheral surface of one end of the bobbin 31. On the other hand, as shown in FIG.
4 is a loop, and both sides thereof are reels 35 and 36, respectively.
To take up. Next, as shown in FIG. 11, the center loop portion 34 of the conductor 33 is half-wound around the turn-back guide 32 of the bobbin 31, and the conductors 33a and 33b on both sides are spirally wound in parallel with the bobbin 31 to form a non-inductive coil. Make it.

[0015]

However, the conventional non-inductive coil has the following problems. Since it is necessary to start winding from the center 34 of the conductor, a centering step using two reels 35 and 36 is required, and the manufacturing process becomes complicated. In order to increase the current capacity, the diameter of the conductor is inevitably increased due to the twisting and the like, so that the outer diameter of the return guide 32 must be increased accordingly, and the structure of the coil There is a limit in increasing the capacity. That is, the conductor has a limit in the bending diameter according to the thickness, and when the bending diameter is small, the superconducting characteristics (particularly, the critical current density Jc) decrease due to an increase in the strain applied to the conductor. Therefore, in order to non-inductively wind a thick conductor, the diameter of the folded guide 32 must be increased. However, since there is a structural upper limit in making the outer diameter of the return guide 32 larger than the outer diameter of the bobbin 31, a conductor having a thickness that requires a bending diameter larger than the limit cannot be used. Since the outer diameter of the turn guide 32 is larger than the winding width (pitch) of the conductor spirally wound, the conductor led out of the turn guide 32 does not become parallel until it reaches the normal spiral winding portion, so that the inductance is minimized. Can not be converted. Since the turn-back guide 32 is provided on the peripheral surface of the bobbin, the inner diameter of the superconducting magnet installed coaxially outside the coil must be increased, and the entire permanent current switch becomes large, and the magnetic field of the superconducting magnet increases. This is disadvantageous in terms of uniformity of distribution and increase in volume.

The present invention has been made to solve these problems, and it is therefore an object of the present invention to provide a small, high current capacity permanent magnet having a small and reliable non-inductive coil which is easy to manufacture. It is to provide a current switch.

[0017]

SUMMARY OF THE INVENTION The object of the present invention is to provide a non-inductive coil having at least one end face of a bobbin of which a coil conductor can be wound in an S-shape on this end face. A member is provided, and an intermediate portion of the coil conductor for the permanent current switch is folded back and wound in an S-shape along the folding member, and coil conductors extending from both sides of the folding are formed in the same direction on the peripheral surface of the bobbin. This can be solved by providing a permanent current switch that is spirally wound in parallel.

This folded member is composed of two cylindrical projections each having an outer diameter smaller than one half of the outer diameter of the bobbin, and both of these projections are located inside the outer periphery of the bobbin on one diameter of the bobbin. It is preferable that they are formed in contact with each other. Here, since the folded member may be substantially a projecting member capable of winding the conductor in an S-shape on the end face,
In addition to the above cylindrical projections, cylindrical projections, elliptical columnar projections,
It may be formed from a polygonal columnar projection, a semi-cylindrical projection, a semi-cylindrical projection, or the like.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below with reference to the accompanying drawings. (Embodiment 1) FIG. 1 shows an embodiment of the coil of the present invention. In FIG. 1, a coil 10 is schematically shown as a bobbin 11.
And a conductor 12 wound therearound.
The bobbin 11 is provided on one end face 13 thereof with a protruding folded member 14 that can wind the conductor 12 in an S-shape on the end face 13. This folded member 14 is
As shown in FIG. 2, each of the outer diameters D of the bobbin 11 is 1 /
Two cylindrical projections 14a having an outer diameter d smaller than 2;
The projections 14a and 14b are formed on one diameter of the bobbin 11 so as to be inscribed in the outer periphery of the bobbin 11. Therefore, both projections 14a, 14b
A gap 15 through which the conductor 12 can pass is formed therebetween.

The conductor 12 is wound as follows.
That is, as shown in FIG. 3, the conductor 12 is wound in an S-shape at the intermediate portion thereof along the outer periphery of the two projections 14 a and 14 b and through the gap 15, and is wound around the folded portion. The conductors 12a and 12b extending from both sides are shown in FIG.
As shown in the figure, the bobbin 11 is spirally wound in parallel on the peripheral surface in the same direction.

In the coil 10, the conductor 12 is folded in an S-shape by a folding member 14, and the conductors 12a and 12b on both sides of the folding are spirally wound on the peripheral surface of the bobbin 11 in the same direction. Therefore, when a current flows from one end of the conductor of the coil 10 (for example, the terminal A of the terminal 12a), the direction of the current is reversed between the adjacent conductors 12a and 12b, and the inductance is canceled each other. In addition, the conductors 12a and 12b respectively derived from the folded member 14 do not have any disorder in parallelism. Therefore, the induced voltage induced in the coil due to the magnetic field fluctuation accompanying the excitation and demagnetization of the superconducting magnet can be minimized, and the non-inductive property is realized. Further, the coil terminal voltage generated due to the flow of current into and out of the coil and the change in the control magnetic field is minimized.

Although the diameter d of the two projections 14a and 14b may be the same or different, the coil 10 is such that the bent diameter of the conductor 12 at the time of folding is the outer diameter d of each of the projections 14a and 14b of the folded member 14. Therefore, it is preferable that both have the same diameter and the maximum diameter within an allowable range. It is sufficient that a gap 15 through which the conductor 12 passes is provided between the two protrusions 14a and 14b. If the outer diameter d of the protrusions 14a and 14b is designed to be large within this range, the conductor 1
Bending diameter that does not adversely affect the superconducting characteristics (critical current density Jc) of No. 2 can be achieved. On the peripheral surface of the bobbin 11, the conductors 12 are spirally wound in parallel with each other.
It is preferable that a spiral guide groove (not shown) is formed.

Since the coil 10 has no protrusions on the peripheral surface of the bobbin 11, the outer diameter is substantially smaller than that of the conventional coil, and therefore, the coil 10 can be inserted into a superconducting magnet having a smaller diameter than that required conventionally. The entire permanent current switch device can be reduced in size. Further, since the gap between the coil 10 and the superconducting magnet can be minimized, the uniformity of the magnetic field distribution and the volumetric efficiency of the superconducting magnet are also improved.

When winding the conductor 12, the coil 10 draws out one end of the conductor 12 from the reel, and the bobbin 11
When the conductor 12a is spirally wound, for example, from the side where the folding member 14 is not attached to the end of the folding member 14, the S-shaped winding is performed around the folding member 14, and the bobbin is already wound. By winding the conductor 12b in parallel in the gap between the conductors 12a spirally wound above, a coil of non-induction winding is formed. Therefore,
Unlike a conventional non-induction winding coil, a centering step using two reels to start winding from the center of the conductor is not required, and the manufacturing process is simplified.

As shown in the first embodiment, in the permanent current switch of the present invention, in the non-inductive coil, the conductor is folded and wound in an S shape by a folding member, and the conductors extending from both sides of the folding are formed of bobbins. Since it is spirally wound in parallel in the same direction on the peripheral surface, if a direct current flows from one end of the coil, the direction of the current will be reversed between adjacent conductors, the inductance will be canceled each other, and the inductive To achieve. Since the conductor is gently folded into an S shape by the folding member, deterioration of the superconducting characteristics due to bending strain can be prevented. This coil has substantially no outer diameter since there is no protrusion on the peripheral surface, and can be inserted into a superconducting magnet having a relatively small diameter.

(Embodiments 2 to 8) In Embodiment 1 described above, the folded member 14 has two cylindrical projections 14a, 1
4b, the folded member substantially corresponds to the conductor 12
Any shape may be used as long as it can be wound in an S-shape on the end face 13, so that various shapes other than those in the first embodiment can be used. 5 (a) to 5
(G) shows an embodiment having a folded member other than the cylindrical projection. In the following examples, the configuration is the same as that of the first embodiment except for the shape of the folded member, and the description thereof is omitted.

(Embodiment 2) In FIG. 5A, the folded member is composed of two columnar projections 16a and 16b. (Embodiment 3) In FIG. 5 (b), the folded member is composed of two columnar projections 17a and 17b, each of which has a notch formed on a side surface where the conductor 12 does not contact. (Embodiment 4) In FIG. 5 (c), the folded member is composed of two semi-cylindrical projections 18a and 18b arranged so that the convex surfaces are opposite to each other. (Embodiment 5) In FIG. 5D, the folded member is composed of two polygonal columnar projections 19a and 19b. (Embodiment 6) In FIG. 5 (e), the folded member is composed of two elliptical columnar projections 20a and 20b. (Embodiment 7) In FIG. 5 (f), the folded member is composed of two semi-cylindrical projections 21 whose convex surfaces are arranged in opposite directions.
a and 21b. (Eighth Embodiment) In FIG. 5 (g), the folded member is composed of two groups of nail-like projection rows 22a and 22b, and the nail-like projection rows of each group form a convex surface on the side surface 13 integrally. And their convex surfaces are opposite to each other. The shape of the folded member is not limited to the above embodiment, and it goes without saying that various deformations are possible including, for example, a semi-elliptical columnar projection, a semi-elliptic cylindrical projection, and the like.

The self-inductance (L) of the coil 10 of Example 1 was measured. This coil 10
The diameter D of the bobbin 11 is 30 mm, the diameter d of each of the cylindrical projections 14a and 14b of the return member is 13 mm, the height is 5 mm, the diameter of the conductor 12 is 1.0 mm, and the length of the conductor wound on the coil. Was 21.5 m. When the self-inductance (L) was measured for this coil,
It was 1.2 μH. This is a very small value,
It was a substantially non-inductive coil.

Similarly, the self-inductance (L) of the coil of Example 3 was measured and found to be 1.2 μH.
Substantially the same results as in Example 1 were obtained. Similarly, when the self-inductance (L) of the coil of Example 4 was measured, it was 1.2 μH, and a result substantially similar to that of Example 1 was obtained.

[0030]

The non-inductive coil of the permanent current switch according to the present invention is provided with a protruding folding member on one end face of the bobbin, on which a conductor can be wound in an S-shape on this end face. Is wound along this in an S-shape, and conductors extending from both sides of the turn are spirally wound in parallel in the same direction on the peripheral surface of the bobbin. There is no need to start winding from the center, and a centering step using two reels is not required, and the manufacturing process is simplified. Since the diameter of the folded member can be increased, a decrease in superconducting characteristics (particularly, critical current density Jc) due to bending strain applied to the conductor can be prevented. Since the conductor led out of the folded member is immediately spirally wound in parallel, there is no non-parallel portion in the coil, and the inductance can be minimized. Since no turn-back guide is provided on the peripheral surface of the bobbin, the substantial outer diameter of the coil can be reduced, so that the entire permanent current switch can be reduced in size and the efficiency of the superconducting magnet can be improved. By using the above-mentioned non-inductive coil, the permanent current switch of the present invention has advantages of small size, low cost, and large current capacity.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a non-inductive coil used for a permanent current switch according to the present invention.

FIG. 2 is a side view of the bobbin used in the embodiment of FIG. 1 as viewed from an axial direction.

FIG. 3 is a side view of the embodiment of FIG. 1 as viewed from the axial center direction.

FIG. 4 is a side view of the embodiment of FIG. 1 as seen from a direction perpendicular to the axis.

FIG. 5 (a) (b) (c) (d) (e) (f)
(G) is a side view as seen from the axial direction, showing an embodiment other than the embodiment shown in FIG. 1.

FIG. 6 is a circuit diagram showing an operation mode of an example of the superconducting magnetic energy storage device.

FIG. 7 is a circuit diagram showing another operation mode of the superconducting magnetic energy storage device shown in FIG.

FIG. 8 is a circuit diagram showing still another operation mode of the superconducting magnetic energy storage device shown in FIG.

FIG. 9 is a perspective view showing an example of a bobbin used in a conventional permanent current switch coil.

FIG. 10 is a plan view showing one process of a conventional non-induction winding.

FIG. 11 is a perspective view showing an example of a conventional permanent current switch coil.

[Explanation of symbols]

10: coil for permanent current switch, 11: bobbin,
12, 12a, 12b ... conductor, 13 ... bobbin side surface,
14 ... return member, 14a, 14b ... cylindrical projection, D ... bobbin outer diameter, d ... cylindrical projection outer diameter.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Satoru Kono 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. (72) Inventor Jin Honma 7-2-1, Nakayama, Aoba-ku, Aoba-ku, Sendai, Miyagi Prefecture. Tohoku Electric Power Company R & D Center

Claims (2)

[Claims] 1. A permanent current switch having a non-inductive coil, wherein at least one end face of a bobbin of the coil is provided with a protruding folded member capable of winding a coil conductor in an S-shape on the end face. An intermediate portion of the coil conductor for the permanent current switch is folded back in an S-shape along the folding member, and coil conductors extending from both sides of the folding are spirally wound in parallel in the same direction on the circumferential surface of the bobbin. Become a permanent current switch. 2. The folding member according to claim 1, wherein the folding member comprises two cylindrical projections each having an outer diameter smaller than one half of the outer diameter of the bobbin. 2. The permanent current switch according to claim 1, wherein the permanent current switch is formed so as to be inscribed in an outer periphery.