JPH09233693A - Impedance variable type component, and impedance variable type current limiter, and impedance variable type superconductive converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a converter which enables the power conversion operation at ultralow temperature. SOLUTION: When a current is applied to a control coil 18B, the impedance ZB of a component 10B becomes extremely large. On the other hand, if a current is not applied to the control coil 18A, the impedance ZA becomes small. Accordingly, charge is performed from a power source E to a capacitor 31, but due to the large impedance ZB, the current is not applied to load 40. Next, a current is applied to the control coil 18A and a current is not applied to the control coil 18B, whereupon the charge of the capacitor 31 flows to the load 40, passing through the component 10B. This operation is performed alternately, and AC power is supplied to the load 40 from a DC power source E.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impedance variable type element device capable of performing a switching operation by giving a phase change of superconducting / normal conducting to a superconductor by a magnetic field generating section, and an impedance variable type device using the same. The present invention relates to a variable impedance type superconducting converter used for DC / AC power conversion for a DC superconducting power transmission cable, which is promising as an electric power application of a current limiting device and a high temperature superconducting material.

[0002]

2. Description of the Related Art Generally, a power semiconductor converter is used as a high-current limiter or as a means for converting direct current into alternating current or for limiting current.

[0003]

The superconductor has zero electric resistance in terms of direct current, but when used in alternating current, alternating current loss occurs. This loss becomes a large value at the operation of 50 and 60 Hz which is a commercial frequency, and a huge amount of liquid nitrogen or cryogenic H
The cable must be cooled using cooling cold such as e-gas. This is a major obstacle to the practical application of AC superconducting power transmission cables. It is known that if the cable current is changed to DC, there is no AC loss from the superconductor and the characteristics of superconductivity can be utilized to the maximum extent. However, since all current power systems operate in alternating current, direct current must be converted to alternating current. Since the current power semiconductor converter operates at room temperature, it is necessary to pull out the cable cooled to an extremely low temperature to room temperature, which causes a large thermal loss. Further, since the loss generated in the semiconductor converter is enormous, the overall efficiency is significantly reduced. For this reason, it has been considered that DC superconducting power transmission cannot be put to practical use. In order to solve this, it is essential to develop a device that can efficiently convert DC current into AC current at cryogenic temperatures.

Therefore, the present invention enables a cryogenic operation of power conversion, which was impossible with the conventional semiconductor converter, and realizes an efficient DC superconducting power transmission cable. It is an object to provide a variable current limiter and a variable impedance superconducting converter.

[0005]

The variable impedance element device according to the present invention comprises a yoke forming a closed magnetic circuit, a cylindrical superconductor wound on the yoke, and an insulating film on the cylindrical superconductor. And a magnetic field generator for changing the impedance of the main coil between small and large by giving a superconducting / normal conducting phase change to the tubular superconductor.

In the variable impedance type fault current limiter according to the present invention, a yoke forming a closed magnetic circuit, a cylindrical superconductor wound on the yoke, and an insulating film interposed on the cylindrical superconductor. A wound main coil, a magnetic field generating unit that changes the impedance of the main coil between small and large by giving a superconducting / normal conducting phase change to the tubular superconductor, and a primary connected in series with the main coil. The current transformer includes a winding and a secondary winding that supplies the induced current to the magnetic field generation unit.

Further, in the variable impedance superconducting converter according to the present invention, a yoke forming a closed magnetic path, a cylindrical superconductor wound on the yoke, and an insulating film on the cylindrical superconductor are interposed. Two variable impedance element units each including a wound main coil and a magnetic field generating unit for switching the impedance of the main coil between small and large by applying the superconducting / normal conducting phase change One end of the main coil connected in series is connected to one pole of the DC power supply, the other end is connected to one end of the load, and the other end of the load is connected to the other pole of the DC power supply. A capacitor is connected between the connection point of the variable impedance element and the other pole of the DC power source, and superconducting / normal conducting phase changes are alternately applied to the cylindrical superconductors of the two variable impedance elements. Porcelain Those having a generator.

Further, a synthetic transformer is used instead of the capacitor.

Further, in the magnetic field generator of each variable impedance element, a control coil is wound around an auxiliary yoke branched from the yoke forming the closed magnetic path, and the control coil is energized. To generate a magnetic field.

[0010]

In the variable impedance element device of the present invention, when the magnetic field is energized to generate a magnetic field, the cylindrical superconductor changes its phase from the superconducting state to the normal conducting state, and the impedance of the main coil rapidly increases. , Switching is performed.

Further, in the variable impedance type current limiter of the present invention, when a large current flows through the main coil, the
A current is induced in the next winding, which flows into the auxiliary coil to generate a magnetic field from the magnetic field generation unit, and the impedance of the variable impedance element rapidly increases, thereby limiting the current.

In the variable impedance type superconducting converter of the present invention, a columnar iron yoke is covered with a cylindrical superconductor, a cylindrical electric insulating material is covered thereover, and a main coil is wound on the cylindrical superconducting material. A series of main coil and tubular superconductor by controlling the superconducting characteristics of the tubular superconductor by controlling the energization of the auxiliary coil of the external magnetic field generator by connecting the Two impedance variable type element units that can change the impedance created by the circuit are prepared, and the control magnetic field of each impedance variable type element unit is alternately generated to alternately change the impedance of the variable impedance type element unit. Alternates the direct current flowing through the element unit and combines two variable impedance element units and capacitors Luke, or by combining the varying current in the synthesis transformer, is intended to convert direct current to alternating current.

[0013]

1 and 2 are a front view and a plan view showing the configuration of an embodiment of the variable impedance element according to the present invention. In FIG. 1, reference numeral 10 is a variable impedance type element unit (hereinafter, simply referred to as an element unit), and FIG. 3 is an enlarged central portion thereof.

As shown in FIGS. 1 to 3, the element unit 10 covers a central yoke 11, which is a part of a yoke forming a closed magnetic circuit, with a cylindrical superconductor 12 having a cylindrical shape or a rectangular tube shape. An insulating film 13 is coated on the main coil 14 and
It is a structure that winds. The main coil 14 and the cylindrical superconductor 12 are connected in series. Reference numerals 15 and 16 are outer yokes that form a closed magnetic circuit together with the central yoke 11. Reference numeral 17 denotes an auxiliary yoke, which is provided so as to be branched from the outer yokes 15 on both sides in a direction orthogonal to the central yoke 11, and a control coil 18 is wound on the auxiliary yoke 17, and the auxiliary yoke 17 and the control coil 18 are provided. The magnetic field generator 19 is configured. The magnetic field generator 19 is provided with a control means for controlling the energization of the control coil 18, but the illustration is omitted.

Now, the equivalent impedance Z of the element unit 10
Is composed of an inductance L and a resistance R formed by a superconductor as shown in FIG. When the tubular superconductor 12 is in the superconducting state, the resistance R is zero, and the magnetic flux generated by the main coil 14 due to the diamagnetic characteristic of the superconductor is the central yoke 1.
Since it does not reach 1, the inductance L of the main coil 14 is the same as that of the air-core coil and has a very small value, and the impedance Z (jwL + R) of the element unit 10 has a very small value. However, the control coil 18 shown in FIGS.
When the superconducting state of the tubular superconductor 12 is destroyed by applying a current to the tubular superconductor 12, the tubular superconductor 12 exhibits an electric resistance R and the main coil 1
Since the magnetic flux created by 4 loses the diamagnetic property of the cylindrical superconductor 12, it reaches the central yoke 11 at the center and a large inductance L is generated, and the impedance Z of the element unit 10 becomes a very large value. This means that the control coil 18
By controlling the characteristics of the cylindrical superconductor 12 with the
That the value of the impedance Z of can be changed significantly, that is,
This means that a kind of switching operation can be performed.

FIG. 5 is a diagram showing the configuration of an embodiment of the variable impedance type current limiting device according to the present invention. This embodiment is constructed by using the element unit 10 shown in FIGS. 5, the same symbols as those in FIGS. 1 to 3 indicate the same parts, 20 is an impedance variable current limiter (hereinafter, simply referred to as current limiter), 21 is a current transformer, and primary windings 22 and 2 are shown.
The secondary winding 23 is composed of a secondary winding 23 and a yoke 24. The primary winding 22 is connected in series with the main coil 14, and the secondary winding 23 is connected at both ends thereof to both ends of the control coil 18.

The basic principle of the fault current limiter 20 is that when the current flowing through the fault current limiter 20 is small, the magnetic flux does not reach the central yoke 11 due to the magnetic shielding effect of the tubular superconductor 12 and the main coil 14 does not move.
Has a low impedance. However, when a fault current flows, the magnetic flux generated by the main coil 14 reaches the central yoke 11, and the impedance suddenly increases to control the flowing current. Since the control coil 18 of the element unit 10 is used in the present invention, the current limiting characteristics can be freely controlled by making the coupling coefficient of the primary winding 22 and the secondary winding 23 variable. Further, since the auxiliary yoke 17 is provided, the magnetic flux is concentrated and the superconducting characteristics of the tubular superconductor 12 are rapidly destroyed, so that the responsiveness is excellent. It should be noted that a switch can be provided in series with the main coil 14 and the switch can be opened for quick recovery.

FIG. 6 is a basic circuit diagram of an embodiment of a variable impedance type superconducting converter (inverter) according to the present invention. Reference numeral 30 denotes a variable impedance type superconducting converter, which is a direct current to an alternating current when a capacitor is used. Is what you get. 10A and 10B are element units, and 18A and 1
8B is a control coil, 31 is a capacitor, 40 is a load, and others are the same as in FIGS.

FIG. 7 is an equivalent circuit of the variable impedance type superconducting inverter shown in FIG. 6, and FIG. 8 shows the timing of the current flowing through the control coils 18A and 18B and the impedance change of the element unit 10 caused thereby. It is shown. 7, the same components as those in FIG. 1 are designated by the same reference numerals, and φ _A and φ _B are control coils 18A,
The current flowing through 18B is shown.

The operation of FIG. 7 will be described with reference to the timing chart of FIG. From time t _{0 to} time t ₁ shown in FIG. 8, the current φ _B of the control coil 18B is being energized and the element unit 10
The impedance Z _{B of B} is large, and the impedance Z _A
Becomes a small value. This is because the charging current flows from the power supply (ad side) E to the capacitor 31 (solid line in FIG. 7).
Means that. However, at this time, the impedance Z _B is so large that the current from the capacitor 31 to the load 40 is extremely small. At time t ₁ ~t _2, since Z _A is very large Z _B decreases, the charge stored in the capacitor 31 flows toward the load 40 (broken line in FIG. 7), from the power source E to the capacitor 31 Almost no charging current flows. By repeating this, the fluctuating voltage shown in FIG. 9 appears in the load 40, and the direct current can be converted into the alternating current.

FIG. 10 is a basic circuit diagram showing another embodiment of the variable impedance type superconducting converter according to the present invention, in which a synthetic transformer 32 is used instead of the capacitor 31 of the embodiment of FIG.

In FIG. 10, 33A and 33B are primary windings connected in series, 33C is a secondary winding, 34 is a yoke, and 35 is an intermediate tap at the connection point between the primary windings 33A and 33B. Wired. Others are the same as in FIG.

Next, the operation will be described. Control current ICl
When is on, the cylindrical superconductor 12 of the element unit 10A is broken and the magnetic flux reaches the central yoke 11, so that the main coil 1
The impedance of 4 becomes large and it becomes difficult for current to flow. On the other hand, the impedance of the element unit 10B is low. As a result, the current I ₂ flows through the synthetic transformer 32. Conversely, when the control current IC2 is on, the impedance of the element unit 10B is large, so that the current I ₁ flows through the composite transformer 32. Since the directions of the currents I ₁ and I ₂ are opposite, the magnetic flux in the composite transformer 32 changes alternately, and the secondary winding 33
AC power can be obtained at C.

[0024]

As described above, the element device according to the present invention is provided with the magnetic field generator, and the magnetic field generated by this causes a phase change of superconducting / normal conducting to the cylindrical superconductor to control impedance. Since it does, switching can be performed.

Further, since the current limiting device according to the present invention is constructed by using the above-mentioned element devices, the current limiting characteristics can be changed and the response speed can be increased.

Further, the variable impedance superconducting converter according to the present invention controls the impedance of the element unit by controlling the diamagnetic characteristic of the superconductor by the magnetic field generating means, and utilizes the impedance change of the two element units. Therefore, it is possible to convert from direct current to alternating current in a cryogenic environment where a superconducting phenomenon appears. Further, since the capacitor (other than the electrolytic solution type) or the synthetic transformer to be used operates without any trouble even in an extremely low temperature state, it is possible to install the entire circuit in an extremely low temperature environment. When connecting a DC power system, which is good at superconductivity, to a normal AC power system that operates at room temperature, a cooled current lead called a power lead is required to introduce current from room temperature to a cryogenic environment. At the same time, a power semiconductor conversion element is required. With such a configuration, a large amount of heat is introduced from the power lead, and the loss of the semiconductor converter is enormous, so that the efficiency of the entire system is significantly reduced. If the present invention is utilized, there is almost no resistance loss as in a semiconductor converter, and since it can operate in a cryogenic environment, efficiency can be greatly improved and a DC power device using superconductivity can be realized.

[Brief description of drawings]

FIG. 1 is a front view showing a configuration of an element device according to the present invention.

FIG. 2 is a plan view of the embodiment of FIG.

FIG. 3 is a detailed view of a basic component part of the element device.

FIG. 4 is an equivalent circuit diagram of the variable impedance element of the embodiment of FIGS.

FIG. 5 is a diagram showing a configuration of an embodiment of a current limiting device according to the present invention.

FIG. 6 is a diagram showing the configuration of an embodiment of a variable impedance superconducting converter according to the present invention.

FIG. 7 is an equivalent circuit diagram of the embodiment of FIG.

FIG. 8 is a diagram showing the energization timing of the control coil and the impedance change of the element unit in the embodiment of FIG. 6;

9 is a diagram showing an output waveform after conversion in the embodiment of FIG.

FIG. 10 is a circuit diagram showing a configuration of another embodiment of the variable impedance type superconducting converter according to the present invention.

[Explanation of symbols]

 10 Impedance variable type element device 10A Impedance variable type element device 10B Impedance variable type element device 11 Central yoke 12 Cylindrical superconductor 13 Insulating film 14 Main coil 15 Outer yoke 16 Outer yoke 17 Auxiliary yoke 18 Control coil 19 Magnetic field generation Part 20 Impedance variable type current limiter 21 Current transformer 22 Primary winding 23 Secondary winding 24 Yoke 30 Impedance variable type superconducting converter 31 Capacitor 32 Composite transformer 33A Primary winding 33B Primary winding 33C Secondary winding Wire 34 Yoke 35 Middle tap 40 Load

Claims (7)

[Claims] 1. A yoke forming a closed magnetic circuit, a tubular superconductor wound on the yoke, a main coil wound on the tubular superconductor via an insulating film, and the tubular superconductor. 2. A variable impedance element device, comprising: a magnetic field generator for switching the impedance of the main coil between small and large by applying a superconducting / normal conducting phase change to the main coil. 2. The magnetic field generation unit comprises a control coil wound around an auxiliary yoke branched from a yoke forming the closed magnetic circuit, and a magnetic field is generated by energizing the control coil. The variable impedance element according to claim 1. 3. A yoke forming a closed magnetic circuit, a tubular superconductor wound on the yoke, a main coil wound on the tubular superconductor via an insulating film, and the tubular superconductor. A magnetic field generator that changes the impedance of the main coil between small and large by applying a superconducting / normal conductive phase change to the main coil; An impedance variable current limiter, comprising: 4. The magnetic field generating section comprises a control coil wound around an auxiliary yoke branched from a yoke forming the closed magnetic path, and a magnetic field is generated by energizing the control coil. The variable impedance type fault current limiter according to claim 3. 5. A yoke forming a closed magnetic circuit, a tubular superconductor wound on the yoke, a main coil wound on the tubular superconductor via an insulating film, and the superconducting / normal conducting Two variable impedance type element units each of which is provided with a magnetic field generating unit that gives a phase change and switches the impedance of the main coil between small and large are connected in series, and the main coils connected in series are connected to each other. One end of the DC power supply is connected to one end of the load, the other end is connected to the other end of the DC power supply, and the other end of the DC power supply is connected to the connection point of the two variable impedance element units and the DC power supply. A capacitor is connected between the other pole and a control unit that alternately applies a superconducting / normal conducting phase change to the cylindrical superconductors of the two variable impedance element units from the magnetic field generating units. Supply AC power to the load An impedance variable type superconducting converter characterized by the following. 6. A yoke forming a closed magnetic circuit, a tubular superconductor wound on the yoke, a main coil wound on the tubular superconductor via an insulating film, and the superconducting / normal conducting Two variable impedance element units each of which has a magnetic field generating unit for giving a phase change and switching the impedance of the main coil between small and large are connected in series with each main coil with a primary winding of a composite transformer interposed. Then, connect a DC power supply between the center tap of this primary winding and the end of the main coil, and
A control unit for alternately applying a normal conduction phase change to the cylindrical superconductors of the two variable impedance element units from the magnetic field generation units is provided, and a predetermined AC power source is obtained in the secondary winding of the composite transformer. An impedance variable type superconducting converter characterized by the following. 7. The magnetic field generator is configured such that a control coil is wound around an auxiliary yoke branched from a yoke forming the closed magnetic path, and a magnetic field is generated by energizing the control coil. The variable impedance superconducting converter according to claim 5.