JP2002111273A - Magnetic shield transformer - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a magnetic shield transformer in which a magnetic path is surrounded by a bulk high-temperature superconductor, thereby reducing leakage flux, energy loss due to iron loss, and efficiency reduction. SOLUTION: A magnetic path of a magnetic flux formed between a primary coil and a secondary coil is surrounded by a bulk high-temperature superconductor, and the bulk high-temperature superconductor is formed by bonding a plurality of bulk high-temperature superconductors. Features. Further, a bulk high-temperature superconductor is inserted between the primary coil and the secondary coil to prevent the formation of magnetic paths other than the magnetic path of the magnetic flux. The magnetic path of the magnetic flux may be an air core or a ferromagnetic core.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic shield transformer in which magnetic shielding is performed by using a bulk high-temperature superconductor having characteristics of high critical current density, and more particularly, to a magnetic path of a large transformer using a plurality of bulk high-temperature superconductors. The present invention relates to a technology that is effective for creating a high-efficiency and lightweight transformer in a large-capacity and high-frequency region by surrounding the device.

[0002]

2. Description of the Related Art An example of a conventional transformer is shown in FIG. FIG. 1 is a cross-sectional view of a conventional transformer. A primary coil 1 and a secondary coil 2 are wound around a ferromagnetic material such as a ferrite or an iron core as a core 6. The operating principle is that, when a voltage is applied to the primary coil 1 as is well known, a current flows through the coil 1 and a magnetic flux is generated.

[0003] Efficiency can be improved by using a ferromagnetic material such as ferrite or iron core for the core 6. Since the primary coil 1 is wound around the ferromagnetic core 6, the magnetic flux passes through the core 6 and reaches the secondary coil 2. Therefore, a voltage is induced in the secondary coil 2 by the measurement of the electromagnetic induction, and the value is determined by the turns ratio between the primary coil 1 and the secondary coil 2.

[0004]

In the conventional transformer, when the current flowing through the coil increases and the magnetic flux generated by the coil increases, magnetic saturation occurs in the core portion and leakage magnetic flux occurs, thereby increasing the efficiency of the transformer. However, there is a problem that is reduced.

[0005] Another problem is that energy loss occurs due to iron loss or the like and efficiency is reduced.

Further, when the transformer is used in a high-frequency region, there is a problem that a skin effect occurs in a core portion using a ferromagnetic material and the efficiency is reduced.

Further, since a magnetic path is formed by a closed core,
There was a problem that the weight increased.

[0008] The present invention has been made under such a background. Leakage is achieved by using an air core or a magnetic core only for the primary and secondary coil portions and by surrounding the magnetic path with a bulk high-temperature superconductor. It is an object of the present invention to provide a magnetic shield transformer in which problems of energy loss and efficiency reduction due to magnetic flux and iron loss are reduced.

It is another object of the present invention to provide a transformer which is lightweight and can be used with high efficiency in a large capacity and high frequency range by the above-mentioned structure.

[0010]

According to a first aspect of the present invention, there is provided a magnetic shield wherein a magnetic path of a magnetic flux formed between a primary coil and a secondary coil is surrounded by a bulk high-temperature superconductor. Provide a transformer.

According to a second aspect of the present invention, in the magnetic shield transformer according to the first aspect, the bulk high-temperature superconductor is formed by bonding a plurality of bulk high-temperature superconductors while ensuring a predetermined contact area. It is characterized by becoming.

According to a third aspect of the present invention, in the magnetic shield transformer according to the first or second aspect, a bulk high-temperature superconductor is inserted between the primary coil and the secondary coil, and the magnetic flux of the magnetic flux is reduced. The formation of a magnetic path other than the path is prevented.

[0013] The invention according to claim 4 is the invention according to claims 1 to 3.
In the magnetic shield transformer according to any one of the above, a core made of a ferromagnetic material is disposed in the magnetic path of the magnetic flux of the inner part of the primary coil and the inner part of the secondary coil, and the remaining magnetic path of the magnetic flux Is characterized as having an air core.

[0014] The invention according to claim 5 provides the invention according to claims 1 to 3.
Wherein the magnetic path of the magnetic flux is air-core.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of a magnetic shield transformer according to an embodiment of the present invention. FIG. 1 (a) is a transverse sectional view, and FIG. 1 (b) is a longitudinal sectional view.

In FIG. 1, the bulk high-temperature superconductor 3 is
It is a plate-shaped high-temperature superconductor having a predetermined thickness, and is used by bonding a plurality of them. By bonding a plurality of bulk high-temperature superconductors, a large-sized transformer can be manufactured. The primary coil 1 and the secondary coil 2 are air-core or normal-conducting or superconducting coils using the core 4 only in each of the coil portions. This transformer is entirely cooled by liquid nitrogen.

The principle of operation is as follows. When a voltage is applied to the primary coil 1, a current flows through the coil and a magnetic flux is generated. Since the coil 1 is surrounded by the bulk high-temperature superconductor, which is a diamagnetic material, the generated magnetic flux reaches the secondary coil 2 without leaking to the outside. By using the core 4 only in the portions of the primary coil 1 and the secondary coil 2, it is possible to reduce the leakage magnetic flux of the coil portion. Further, by inserting the bulk high-temperature superconductor 5 between the primary coil 1 and the secondary coil 2, magnetic interference between the primary coil 1 and the secondary coil 2 can be prevented.

In the transformer, a voltage is induced in the secondary coil 2 according to the law of electromagnetic induction, and the value is determined by the turn ratio between the primary coil 1 and the secondary coil 2. With the magnetic shield transformer as described above, it is possible to realize a transformer that is lightweight, has no energy loss due to leakage magnetic flux and iron loss, and can be used with high efficiency in a large capacity and high frequency range.

<Example> An example of the present invention using an experimental apparatus and data obtained will be described in detail with reference to the drawings. FIG. 2 shows an experimental apparatus, in which a transformer composed of a primary coil 1 and a secondary coil 2 is placed in a flask 22 filled with liquid nitrogen 21, and the efficiency of the circuit depending on the presence or absence of the bulk high-temperature superconductor 3 or 5 or the core 4 is shown. It was measured. In addition,
In the figure, the bulk high-temperature superconductor 3 or 5 and the core 4 are not shown.

The voltage signal of a predetermined frequency generated by the function generator 23 is amplified by the power amplifier 24 and applied to the primary coil 1 via the current limiting resistor 5.
The voltage induced in the secondary coil 2 by the electromagnetic induction is consumed by the load resistor 26. The number of turns of each of the primary coil 1 and the secondary coil 2 was 20 turns. The circuit examined here is an air-core circuit, a circuit in which the primary coil 1 and the secondary coil 2 of the air core are surrounded by the bulk high-temperature superconductor 3, and ferrite is used as the core 4 of the primary coil 1 and the secondary coil 2. There are four types of circuits, a circuit in which a primary coil 1 and a secondary coil 2 using ferrite as a core 4 are surrounded by a bulk high-temperature superconductor 3.

FIG. 3 is a cross-sectional view showing the structure of the magnetic shield transformer used in the experiment. FIG.
(B) shows a longitudinal sectional view, and the dimensions of each part are as shown in this figure, and the primary coil 1 and the secondary coil 2 are surrounded by the bulk high-temperature superconductor 3 as shown in FIG. Here, the dimensions of the bulk high-temperature superconductor 3 are based on the use of an existing sample, and are larger than originally required. The dimensions of the bulk high-temperature superconductor 3 shown in FIG. 3B can actually be achieved with the dimensions shown in FIG.

However, a contact portion between the superconductors has a cap, and a current flows in the vicinity of the inner surface of the superconductor, so that a magnetic flux penetrates to some extent. Therefore, the required length of the contact portion between the superconductors is determined by the frequency, the width of the gap, and the magnetic properties of the sample. The minimum value of the thickness of the sample for ensuring the above is determined.

The measurement was carried out with the primary voltage constant at 2.4 V and the frequency as a variable, and with the frequency constant at 2 kHz and the primary current as a variable. In the measurement using the frequency as a variable, the primary and secondary coils were each formed by winding a copper wire having a diameter of 0.2 mm for 20 turns, and in the experiment using the primary current as a variable, the primary and secondary coils were each 0.29 mm in diameter.
The copper wire was wound 20 turns. The resistance value of the load resistor 26 on the secondary side in FIG. 2 was set to 5.1Ω in the measurement using the frequency as a variable, and set to 5 kΩ in the measurement using the primary current as a variable.

FIG. 5 shows the relationship between the frequency and the current flowing through the secondary coil 2. FIG. 5A shows a comparison of the secondary current with and without the bulk high-temperature superconductor in the air core.
(B) shows a comparison of the secondary current depending on the presence or absence of the bulk high-temperature superconductor in the ferrite core. It can be seen that in both the air core and the ferrite core, by surrounding the circuit with the bulk high-temperature superficial conductor, the secondary current value is increased and the characteristics are improved. In particular, a remarkable improvement in characteristics is observed in a high frequency region.

FIG. 6 shows the relationship between frequency and power transmission efficiency. FIG. 6 (a) shows a comparison of the secondary current with and without the bulk high-temperature superconductor in the air core, and FIG. 6 (b) shows a comparison of the secondary current with and without the bulk high-temperature superconductor in the ferrite core. is there. In the case of an air core, an improvement in efficiency can be seen by being surrounded by a bulk high-temperature superconductor in all frequency regions. 5 kHz for ferrite cores
In the above high frequency region, the efficiency is improved by being surrounded by the bulk high-temperature superconductor.

FIG. 7 shows the relationship between the primary voltage and the secondary voltage.
FIG. 7A shows the relationship between the primary voltage and the secondary voltage depending on the presence or absence of the bulk high-temperature superconductor in the air core, and FIG. 7B shows the relationship between the primary voltage and the secondary voltage depending on the presence or absence of the bulk high-temperature superconductor in the ferrite core. This is a relationship between secondary voltages. In both cases of the air core and the ferrite core, the output voltage of the secondary coil was increased and the characteristics were improved by surrounding the circuit with the bulk high-temperature superconductor.

The operation of one embodiment of the present invention has been described above in detail with reference to the drawings. However, the present invention is not limited to this embodiment, and a design change or the like may be made without departing from the gist of the present invention. The present invention is also included in the present invention.

[0028]

As described above, according to the present invention, the following effects can be obtained. (1) By using an air core or core only for the primary and secondary coil portions and surrounding the magnetic path with a bulk high-temperature superconductor, it is possible to reduce energy loss due to leakage magnetic flux, iron loss, and efficiency reduction. (2) A transformer that is lightweight and can be used with high efficiency in a large capacity and high frequency range can be manufactured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a magnetic shield transformer according to an embodiment of the present invention, wherein (a) is a cross-sectional view of the transformer, and (b)
Is a longitudinal sectional view of a transformer.

FIG. 2 is a diagram showing an experimental device of a magnetic shield transformer according to one embodiment of the present invention.

FIG. 3 is a sectional view showing a configuration of a magnetic shield transformer used in an experiment.

FIG. 4 is a diagram showing the originally required dimensions of the magnetic shield transformer of FIG. 3 (b).

FIG. 5 (a) is a diagram showing a relationship between a frequency depending on the presence or absence of a bulk high-temperature superconductor in an air core and a current flowing through a secondary coil, and FIG. The figure which shows the relationship of the current which flows through a coil.

FIG. 6A is a diagram showing a relationship between frequency and power transmission efficiency depending on the presence or absence of a bulk high-temperature superconductor in an air core;
(B) is a diagram showing a relationship between frequency and power transmission efficiency depending on the presence or absence of a bulk high-temperature superconductor in a ferrite core.

7A is a diagram showing a relationship between a primary voltage and a secondary voltage depending on the presence or absence of a bulk high-temperature superconductor in an air core, and FIG.
FIG. 3 is a diagram showing a relationship between a primary voltage and a secondary voltage depending on the presence or absence of a bulk high-temperature superconductor in a ferrite core.

FIG. 8 is a diagram showing an example of a transformer according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Primary coil 2 ... Secondary coil 3 ... Bulk high temperature superconductor 4 ... Core 5 ... Bulk high temperature superconductor 6 ... Core 21 ... Liquid nitrogen 22 ... Flask 23 ... Function generator 24 ... Power amplifier 25 ... Current limiting resistance 26 ... Load resistance

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsuo Hashimoto 4-1-1 Hashimotodai, Hashimotodai, Sagamihara City, Kanagawa Prefecture Inside the staff dormitory of the University of Occupational Ability Development (72) Inventor Katsuhiro Fukuoka Kubozawa, Shiroyama-cho, Tsukui-gun, Kanagawa Prefecture 3-5-11 Villa Takebayashi 3-205 (72) Inventor: Yu Tomita 1-14-3, Shinonome, Koto-ku, Tokyo Foundation International Superconductivity Technology Research Center Inside the Superconductivity Engineering Laboratory (72) Inventor: Takeshi Miyamoto 1-14-3, Shinonome, Koto-ku, Tokyo International Research Center for Superconductivity Technology, Superconductivity Engineering Research Center (72) Inventor Masato Murakami 1-14-3, Shinonome, Shinonome, Koto-ku, Tokyo Technology Research Center F-term in Superconducting Engineering Laboratory (reference) 5E321 AA01 BB60 CC16 GG07

Claims (5)

[Claims] 1. A magnetic shield transformer, wherein a magnetic path of a magnetic flux formed between a primary coil and a secondary coil is surrounded by a bulk high-temperature superconductor. 2. The magnetic shield transformer according to claim 1, wherein the bulk high-temperature superconductor is formed by bonding a plurality of bulk high-temperature superconductors while securing a predetermined contact area. 3. The method according to claim 1, wherein a bulk high-temperature superconductor is inserted between the primary coil and the secondary coil to prevent formation of a magnetic path other than a magnetic path of the magnetic flux. The magnetic shield transformer as described. 4. A core made of a ferromagnetic material is disposed in a magnetic path of the magnetic flux in an inner part of the primary coil and an inner part of the secondary coil, and the remaining magnetic path of the magnetic flux is air-core. The magnetic shield transformer according to any one of claims 1 to 3, wherein 5. The magnetic shield transformer according to claim 1, wherein a magnetic path of the magnetic flux is an air core.