JP2003284240A - Current limiter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized current limiter by putting the current waveform of a current application coil at short circuit in waveform easy to break, and enabling the magnetic flux density of a magnetic core to be set high. <P>SOLUTION: Elements 110A and 110B have soft magnetic cores 21 and the first yokes 22a counterposed, a first permanent magnets 20a and the second yokes 22b in piles clamped between one end of the soft magnetic core 21 and that of the first yoke 22a, and a second permanent magnet 20b and the third yoke 22c in piles clamped between the other end of the soft magnetic core 21 and that of the first yoke 22a. The current-carrying coils 23 are connected in reverse series, being wound on each soft magnetic core 21 of the elements 110A and 110B, and the secondary coils 24 are connected differentially, being wound on each soft magnetic core 21 of the elements 110A and 110B, and a capacitor 25 is interposed between the secondary coils 24. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current limiter for efficiently and instantaneously suppressing an overcurrent generated by a short circuit accident in an electric circuit, and more particularly to a permanent magnet, a soft magnetic core, a current-carrying coil, a secondary coil and a capacitor. The present invention relates to a high performance magnetic switching type fault current limiter.

[0002]

2. Description of the Related Art In recent years, dependence on electric energy has been increasing due to convenience in energy utilization. On the other hand, the demands of society for environmental problems are strict, and it is becoming difficult to construct new power generation facilities, contrary to the increasing need for electric energy. In addition, since the power supply margin is limited and the probability of accident occurrence is not zero, an unavoidable electric power accident occurs. Therefore, it is possible to stably supply power without compromising the reliability of the system, to maximize the transmission capacity of the system in response to the immediate increase in power demand, and to avoid hasty equipment upgrades. From this point of view, there is a demand for a measure that can instantly operate when an overcurrent occurs and can cope with a system failure without special control. In order to meet such demands, various magnetic switching type fault current limiters have been proposed in which a permanent magnet having a high coercive force and a high residual magnetic flux density and a magnetic core having a good squareness are combined.

FIG. 19 shows, for example, the Journal of Applied Magnetics of Japan (Vol.
22, No. 10, 1998, p.1317-1322), which is a schematic diagram showing the configuration of a conventional magnetic switching type fault current limiter, FIG.
Reference numeral 0 is a magnetic flux-current diagram for explaining the magnetic operation of a conventional magnetic switching type fault current limiter, and FIG. 21 is an electric circuit diagram incorporating a conventional magnetic switching type fault current limiter.

As shown in FIG. 19, the conventional fault current limiter 1 is constructed by connecting two elements 2 in series so as to have opposite polarities. In each element 2, a permanent magnet 4 having a high coercive force and a high residual magnetic flux density is inserted between a pair of E-shaped magnetic cores 3 having good squareness (ratio of residual magnetic flux density and saturated magnetic flux density is close to 1). The energizing coil 5 is wound around the center side of the pair of magnetic cores 3. The magnetization direction of the permanent magnet 4 inserted between the center sides of the pair of magnetic cores 3 and the magnetization direction of the permanent magnet 4 inserted between both end sides of the pair of magnetic cores 3 are opposite to each other. Is magnetized.

Here, as shown in FIG. 20, the magnetic core 3 of each element 2 is biased to the saturation region A by the permanent magnet 4, and the current value thereof is changed by passing an alternating current through the energizing coil 5. As a result, the operating point of the magnetic core 3 moves from the saturation region A on one side to the unsaturated region B on the one hand, and the saturation region C on the other side, so that the impedance becomes low during normal operation and becomes high at excessive current. So two elements 2
A current limiting function can be obtained by connecting in series so that they have opposite polarities. As shown in FIG. 21, the current limiting device 1 is used by being inserted between the power source side and the load side. Then, during normal operation, a steady current flows through the energizing coil 5, so the magnetic core 3 is in the saturated magnetization region, and there is no change in magnetic flux. As a result, the impedance of the energizing coil 5 is small and the voltage drop in the energizing coil 5 is small, so that the power supply voltage is almost applied to the load (R). On the other hand, switch (S
When W) is closed, that is, when the load (R) is short-circuited and a large current flows in the energizing coil 5, the magnetic cores 3 of the two elements 2 undergo magnetic reversal in the magnetic saturation regions in mutually opposite directions, and Impedance increases. As a result, most of the power supply voltage is applied to the energizing coil 5, and the short circuit current is limited by the current limiter 1 in the high impedance state.

Generally, in the LR series circuit (a circuit in which an inductance (L) and a resistance (R) are connected in series) shown in FIG. 22, for example, the Institute of Electrical Engineers of Japan "Transient Phenomenon" (Showa 28) First edition issued April 1, 68-
As described on page 69, it is known that a transient current depending on the timing of applying a voltage is generated.
Letting i be the current when an AC voltage of e = E _m · sin (ωt + θ) is applied to this LR series circuit at the moment of t = 0, the following differential equation is established from the relationship of voltage balance. L (di / dt) + Ri = E _m sin (ωt + θ) (1) The solution of this differential equation is i = I _m sin (ωt + θ−φ) −I _m (exp ^{−Rt / L} ) · sin (θ− φ) (2) However, I _m = E _m / (R ² + ω
² L ² ) ^1/2 , φ = tan ⁻¹ (ωL / R). The first term of the equation (2) is a steady current, and the second term is a transient current (DC component). Then, from the equation (2), t = 0 of the AC voltage
It can be seen that the transient current changes depending on the phase θ at that time, that is, the timing of voltage application. For example, θ = φ
When, the transient current is zero, and when θ = φ + π / 2, the transient current becomes maximum. Note that the DC component tends to be slower in decay and larger in amplitude as R / L is smaller, and the DC component is attenuated with time, and the amplitude converges to zero in a steady state.

Usually, the operating magnetic flux density of the current limiter magnetic core is set high from the viewpoint of miniaturization of the current limiter magnetic core. That is, when the voltage of the energizing coil is E, the operating magnetic flux density is B, and the magnetic core cross-sectional area is S, the relationship of E∝B · S is established, and S can be decreased as B is increased. At this time, the operating point of the magnetic core moves to the region D in FIG. 20 due to the DC bias due to the transient phenomenon, and an inrush current flows at the time of short circuit.

However, the Journal of Applied Magnetics of Japan (Vol.
22, No. 10, 1998, p. 1317-1322), no consideration was given to the transient phenomenon of the current limiting device. Therefore, the applicant of the present invention describes a result of studying a transient phenomenon using a current limiter model equivalent to the conventional current limiter 1 and using the current limiter model.

FIG. 23 is a schematic diagram showing the structure of a fault current limiter model produced by the present applicant. In FIG. 23, the current limiter 6
In (not known), two elements 7 are connected in series so as to have opposite polarities, that is, the energizing coil 11 of the two elements 7 is connected.
Are connected to form a reverse series. Each element 7 is a soft magnetic core 8 for switching made of a soft magnetic material having a good squareness, for example, directional silicon steel in a flat plate shape.
A yoke 9a made of a soft magnetic material in a flat plate shape and arranged in parallel to face the soft magnetic core 8, and interposed between both ends of the soft magnetic core 8 and the yoke 9a in the longitudinal direction. Permanent magnets 10a, 10b with high coercive force and high residual magnetic flux density
And a yoke 9b which is made of a soft magnetic material into a rectangular parallelepiped and is interposed between the soft magnetic core 8 and the permanent magnets 10a and 10b.
9c and a current-carrying coil 11 wound so as to surround the soft magnetic core 8.

The soft magnetic core 8 is formed in a magnetic path cross-sectional area which is magnetized to the magnetic saturation region by the permanent magnets 10a and 10b when the energizing coil 11 is not energized.
On the other hand, the yokes 9a, 9b, 9c are formed with a magnetic path cross-sectional area larger than that of the soft magnetic core 8, and are in a non-magnetic saturation state. Further, the permanent magnets 10a and 10b are magnetized so that the magnetization directions thereof coincide with the thickness direction of the soft magnetic core 8 and are opposite to each other. As a result, the soft magnetic core 8 constitutes a closed magnetic circuit together with the yokes 9a, 9b, 9c and the permanent magnets 10a, 10b, and the pair of permanent magnets 10a, 10b.
By b, they are magnetized in the arrow directions in FIG.

The current limiting device 6 is used by being inserted between the power source side and the load side, like the conventional current limiting device 1. The soft magnetic core 8 has the same characteristics as the magnetic flux-current diagram of FIG. Therefore, during normal operation, a steady current flows through the current-carrying coil 11, so that the soft magnetic core 8 is in the saturated magnetization region and there is almost no change in magnetic flux. As a result, the impedance of the energizing coil 11 is small,
Since the voltage drop at is small, the power supply voltage is almost applied to the load (R). On the other hand, when the load (R) is short-circuited and a large current flows in the energizing coil 11, the soft magnetic cores 8 of both elements 7 are magnetized to be reversed in the magnetic saturation regions in mutually opposite directions, and the energizing coil 11
The impedance of becomes large. As a result, most of the power supply voltage is applied to the energizing coil 11, and the short-circuit current is limited by the current limiter 6 in the high impedance state.

FIG. 24 shows the results of measuring the coil current waveform and the magnetic core magnetic flux waveform by applying a voltage to the current limiting device 6 at the closing timing when the transient current is almost maximum. In addition, in FIG. 24, 15 represents a coil current waveform and 16 represents a magnetic core magnetic flux waveform. The magnetic flux waveform of the magnetic core is
The coil wound around the soft magnetic core 8 was connected to the reverse series to form a tertiary coil, and the voltage induced in the tertiary coil in the open state was integrated and obtained. Further, the operating magnetic flux density of the soft magnetic core 8 is set to a voltage such that, in a steady state, the saturation magnetic flux density of the grain-oriented silicon steel used for the magnetic core is 2 terraces. Then, FIG. 24A and FIG.
The waveforms of the coil current and the magnetic flux of the magnetic core are shown when the voltage is applied to the current limiter 6 at different timings.

From FIGS. 24 (a) and 24 (b), the coil current waveform changes depending on the voltage application timing, but in both cases, the top of the magnetic flux waveform begins to be clicked at time s, and the soft magnetic core 8 is saturated. I know that Then, it can be seen that the current flowing through the energizing coil 11 is in a closing state in which it rapidly increases due to the saturation of the soft magnetic core 8. An actual current limiting device is designed so that R << ωL in order to reduce the copper loss (ir ² R) due to the load current ir in the electric path during normal operation. Therefore, there is a problem that the peak of the inrush current becomes larger as R / L becomes smaller, and the arc current becomes large at the time of interruption, which makes interruption difficult. Further, by setting the operating magnetic flux density of the soft magnetic core to be small (for example, point B in FIG. 20) and avoiding magnetic saturation due to a transient phenomenon, the inrush current can be reduced or eliminated. However, this requires that the cross-sectional area of the soft magnetic core 8 be increased, resulting in an increase in the volume of the soft magnetic core 8 and the permanent magnets 10a, 10b, and an increase in the size of the current limiting device. The above-mentioned inconvenience in the current limiting device 6 studied by the applicant of the present invention also occurs in the conventional current limiting device 1.

[0014]

As described above, the conventional magnetic switching type current limiting device using the permanent magnet has a problem that it is increased in size in order to suppress the inrush current.

In order to solve the above-mentioned problems, the present invention makes it possible to easily cut off the current waveform of the energizing coil at the time of short circuit, and to set the magnetic flux density of the magnetic core high.
The purpose is to obtain a small current limiting device.

[0016]

A current limiting device according to the present invention includes first and second closed magnetic circuits each including at least a soft magnetic core for switching and a permanent magnet, and the first closed magnetic circuit. A first energizing coil and a first secondary coil wound around the soft magnetic core for switching that constitutes the second magnetic coil, and a second magnetic coil wound around the soft magnetic core for switching that constitutes the second closed magnetic circuit. Energizing coil and second
Secondary coil, the first and second energizing coils are connected in reverse series, the first and second secondary coils are differentially connected, and the differentially connected The open end of the secondary coil is connected via a capacitor.

In each of the first and second closed magnetic circuits, the switching soft magnetic core and the first yoke are arranged to face each other, and the second yoke and the first permanent magnet are laminated. The soft magnetic core for switching and the first
It is sandwiched and joined between one end of the yoke and the third yoke and the second permanent magnet, and sandwiched and joined between the other end of the soft magnetic core for switching and the first yoke. The first and second permanent magnets are magnetized so that the magnetization directions thereof are orthogonal to the joint surface with the switching soft magnetic core and opposite to each other. The core is formed in a magnetic path cross-sectional area that is magnetically saturated by the first and second permanent magnets, and the first to third yokes are formed in a magnetic path cross-sectional area larger than that of the switching soft magnetic core. It has been done.

In the first and second closed magnetic circuits, the first and second soft magnetic cores for switching are arranged to face each other, and the first permanent magnet is used for the first and second switching. A single closed magnet which is sandwiched and joined between one ends of the soft magnetic core, and the second permanent magnet is sandwiched and joined between the other ends of the first and second soft magnetic cores for switching. Circuit, the first energizing coil and the first secondary coil are wound around the first soft magnetic core for switching, and the second energizing coil and the second secondary coil are The first and second permanent magnets are wound around a second soft magnetic core for switching, and the magnetization directions of the first and second permanent magnets are
The first and second soft magnetic cores for switching are magnetized so as to be orthogonal to the joint surface with the soft magnetic cores for switching and opposite to each other. Furthermore, the first and second soft magnetic cores for switching are It is formed in a magnetic path cross-sectional area that is magnetically saturated by the first and second permanent magnets.

In the first and second closed magnetic circuits, the first and second soft magnetic cores for switching are arranged to face each other, and the permanent magnets have the first and second soft magnetic cores for switching. A single closed magnetic circuit sandwiched and joined between one ends of the first and second soft magnetic cores for switching, and a yoke which is sandwiched and joined between the other ends of the first and second soft magnetic cores for switching. The first energizing coil and the first secondary coil are wound around the first switching soft magnetic core, and the second energizing coil and the second secondary coil are
The permanent magnet is wound around the second soft magnetic core for switching, and the permanent magnet is magnetized so that the magnetization direction is orthogonal to the joint surface with the first and second soft magnetic cores for switching.
The first and second soft magnetic cores for switching are formed in a magnetic path cross-sectional area that is magnetically saturated by the permanent magnets.
Further, the yoke is formed to have a larger magnetic path cross-sectional area than the first and second soft magnetic cores for switching.

In the first and second closed magnetic circuits, the first and second soft magnetic cores for switching are arranged to face each other, and the first permanent magnet is used for the first and second switching magnetic circuits. A single closed magnet which is sandwiched and joined between one ends of the soft magnetic core, and the second permanent magnet is sandwiched and joined between the other ends of the first and second soft magnetic cores for switching. A first coil and a second coil, wherein the first and second energizing coils are constituted by a single coil formed by winding the first and second soft magnetic cores for switching so as to collectively surround them. The first secondary coil is wound around the first soft magnetic core for switching, the second secondary coil is wound around the second soft magnetic core for switching, and the first and second soft magnetic cores are wound. Of the permanent magnet of the first and second magnets Perpendicular to the junction surface of the etching for the soft magnetic core, and is magnetized so as to opposite to each other,
Further, the first and second soft magnetic cores for switching are formed in a magnetic path cross-sectional area that is magnetically saturated by the first and second permanent magnets.

Further, in the first and second closed magnetic circuits, the first and second soft magnetic cores for switching are arranged to face each other, and the permanent magnets have the first and second soft magnetic cores for switching. A single closed magnetic circuit sandwiched and joined between one ends of the first and second soft magnetic cores for switching, and a yoke which is sandwiched and joined between the other ends of the first and second soft magnetic cores for switching. The first and second energizing coils are constituted by a single coil formed by winding the first and second soft magnetic cores for switching so as to surround them collectively, and the first secondary coil is The first soft magnetic core for switching is wound around, the second secondary coil is wound around the second soft magnetic core for switching, and the permanent magnet has a magnetizing direction of the first and second soft magnetic cores. Joint surface with second soft magnetic core for switching The first and second soft magnetic cores for switching, which are magnetized so as to be orthogonal to each other, are formed in a magnetic path cross-sectional area that is magnetically saturated by the permanent magnets, and further, the yoke includes the first and second soft magnetic cores. The magnetic path cross-sectional area is larger than that of the switching soft magnetic core.

The capacitor is a polar electric field capacitor.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1. 1 is a perspective view showing the configuration of a current limiting device according to a first embodiment of the present invention, FIG. 2 is a circuit diagram of the current limiting device according to the first embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. 1 is a diagram showing coil specifications in the current limiting device according to the first embodiment, and FIG. 4 is a diagram showing core specifications in the current limiting device according to the first embodiment of the present invention. 1 and 2, the arrow indicates the direction of magnetization of the soft magnetic core, and the black circle in FIG. 2 indicates the polarity.

In FIG. 1, 20a and 20b are rare earth magnets (Nd-Fe-B system, S) which are hard magnetic materials.
m-Co system), and the first and second permanent magnets 20a, 2b.
0b is made of substantially the same material and has a prismatic shape of the same shape.
In addition, it is desirable that the first and second permanent magnets 20a and 20b have magnetic characteristics with a large coercive force and a residual magnetic flux density from the viewpoint of miniaturization of the device. Reference numeral 21 is a soft magnetic core for switching, which is made in the shape of a flat plate from grain-oriented silicon steel which is a soft magnetic material. 22a is a soft magnetic core 2
A first yoke 22b made of the same material as that of 1 and having a flat plate shape,
The second and third yokes 22c are made of the same material as the soft magnetic core 21 and are formed in a rectangular parallelepiped. The materials for the soft magnetic core 21 and the first to third yokes 22a, 22b, 22c are preferably those having high magnetic permeability and good squareness. Also,
The soft magnetic core 21 has characteristics equivalent to those of the magnetic flux-current diagram shown in FIG. Reference numeral 23 is a current-carrying coil made of a low resistance material such as copper, and 24 is a secondary coil made of a low resistance material such as copper.

Here, in the elements 110A and 110B, the soft magnetic core 21 and the first yoke 22a respectively sandwich and sandwich the second yoke 22b and the first permanent magnet 20a between one ends, and the other ends. The third yoke 22c and the second permanent magnet 20b are laminated and sandwiched between the parts, and are arranged so as to face each other and are joined and integrated, and the energizing coil 23 and the secondary coil 24 are provided.
Is wound and configured so as to surround the soft magnetic core 21. Then, the energizing coil 23 (first
(Corresponding to the energizing coil of) and the energizing coil 23 of the element 110B
(Corresponding to the second energizing coil) and the secondary coil 24 of the element 110A (corresponding to the first secondary coil) and the secondary coil 24 of the element 110B (corresponding to the second secondary coil). (Corresponding to) is differentially connected, and both ends of the connected secondary coil 24 are connected via a capacitor 25,
The magnetic switching type fault current limiter 100 is configured. This fault current limiter 100 constitutes the circuit shown in FIG.
The specifications of the current limiting device 100 are as shown in FIGS. 3 and 4.

Here, the first and second permanent magnets 20
a and 20b have their magnetization directions aligned with the direction perpendicular to the surface where the soft magnetic core 21 and the first yoke 22a are joined (the thickness direction of the soft magnetic core 21 and the first yoke 22a), and opposite to each other. It is magnetized so that As a result, in the element 110A, the soft magnetic core 21 has the first and second permanent magnets 20a and 20b and the first to the third permanent magnets.
A first closed magnetic circuit is formed with the yokes 22a, 22b and 22c, and the first and second permanent magnets 20a and 20b are provided.
Is magnetized in the direction of the arrow in FIG. Similarly, element 11
In 0B, the soft magnetic core 21 includes the first and second permanent magnets 20a and 20b and the first to third yokes 22.
A second closed magnetic circuit is formed with a, 22b, and 22c, and is magnetized in the arrow direction in FIG. 1 by the first and second permanent magnets 20a and 20b. In addition, the soft magnetic core 21 is formed in a magnetic path cross-sectional area that is magnetized to the magnetic saturation region by the first and second permanent magnets 20a and 20b when the energizing coil 23 is not energized. On the other hand, the first to third yokes 22a, 22b, 22c are formed to have a magnetic path cross-sectional area larger than that of the soft magnetic core 21, so that they are not magnetically saturated.

Next, the operation of the current limiting device 100 will be described. 21. In the circuit diagram of FIG. 21, the current limiter 100 is configured such that, in place of the current limiter 1, one of the two energizing coils 23 connected in the reverse series is connected to a power source and the other end is connected to a load, It is inserted between the power supply side and the load side. And
The soft magnetic cores 21 of the elements 110A and 110B are biased by the first and second permanent magnets 20a and 20b, respectively, and magnetized to the magnetic saturation region. Then, by passing an alternating current through the energizing coil 23, the operating points of the two soft magnetic cores 21 forming the first and second closed magnetic circuits are
It changes from one saturation region A to the other saturation region C to one saturation region A every half cycle, and has a low impedance during normal operation and a high impedance during excessive current.

Therefore, during normal operation, a steady current flows through each energizing coil 23, so that both soft magnetic cores 21 are in the magnetic saturation region and there is almost no change in magnetic flux. As a result, the impedance of the energizing coil 23 is small and the energizing coil 23
Since the voltage drop at is small, the power supply voltage is almost applied to the load (R). On the other hand, when the load (R) is short-circuited and a large current flows through the energizing coil 23, the magnetizations of the two soft magnetic cores 21 are reversed to the magnetic saturation regions in opposite directions, the impedance of each energizing coil 23 increases, and the power supply voltage increases. Most of them are added to the energizing coil 23. Therefore, the short-circuit current is limited by the current limiter in the high impedance state.

Now, the waveform of the current flowing through the current-carrying coil 23 in the steady state in which the direct current component in the current limiting device 100 is attenuated will be described. First, in the case where there is no capacitor 25 and both secondary coils 24 are differentially connected,
During normal operation without electric circuit short-circuiting, the soft magnetic core 21 is in a magnetic saturation state, so the incremental magnetic permeability of the magnetic core is small, the reactance of the secondary coil 24 is very small, and the voltage drop in the secondary coil 24 is small. Is extremely small. Ideally, when the incremental magnetic permeability is 1, if the number of turns and the cross-sectional areas of both secondary coils 24 are equal, the voltages induced in each secondary coil 24 have the same amplitude and opposite phase, so the total Will be zero. Note that connecting the two secondary coils 24 so that the voltages induced in the respective secondary coils 24 have opposite phases is referred to as differential connection.

On the other hand, when the electric circuit is short-circuited, the elements 110A, 1
In the soft magnetic core 21 of 10B, the operating point of magnetization changes from one saturation region A to the other saturation region C to one saturation region A for each half cycle of the AC voltage. As a result, in the steady state at the time of short circuit, as shown in FIG. 5, a voltage having a double frequency of the power supply voltage is induced in the entire two secondary coils 24 that are differentially connected. For comparison, FIG. 6 shows a voltage waveform induced in the entire two secondary coils 24 connected in the reverse series like the energizing coil 23. The voltage induced across the two secondary coils 24 connected to this reverse series has the same repetition frequency as the power supply voltage, as shown in FIG.

Here, both secondary coils 2 connected differentially
When 4 is connected via the capacitor 25 (200 μF), a current asymmetrical with respect to the time axis (t) flows in the secondary coil 24 when the electric circuit is short-circuited, as shown in FIG. 7. When this current flows through the secondary coil 24, a current symmetrical in the vertical direction with respect to the time axis (t) obtained by reversing a half cycle of the current flowing through the secondary coil 24 is connected in the reverse series according to the electromagnetic induction law. It flows through the entire coil 23. In addition,
The amplitude and phase of the current flowing through the energizing coil 23 by the electromagnetic induction side changes depending on the capacity of the capacitor 25.

Therefore, when the electric circuit is short-circuited, the current flowing through the energizing coil 23 connected to the reverse series of the current limiting device 100 is divided into the current flowing through the energizing coil 23 by the electromagnetic induction side and the current limiting device 100. When the secondary coil 24 is removed (the secondary coil is opened), the current (shown in FIG. 8) flowing through the entire energizing coil 23 connected in the reverse series is added. That is, the current flowing through the entire energizing coil 23 connected to the reverse series of the current limiting device 100 at the time of short-circuiting the electric circuit has a waveform having two peaks in a half cycle and a short rise time, as shown in FIG. . Moreover, these two peak values are smaller than the peak values of the current waveform shown in FIG. In addition, in FIG. 9, 15 represents a current waveform and 16 represents a magnetic flux waveform. In other figures, 15 is a current waveform,
Reference numeral 16 represents a magnetic flux waveform.

In the current limiter 100, the capacitor 2
When 5 was set to 400 μF, when the electric circuit was short-circuited, the current flowing through the entire energizing coil 23 connected in the reverse series had the waveform shown in FIG. 10. Also in this current waveform, the rise time of the current is short. As described above, in the current limiting device 100, the current waveform flowing through the entire energizing coil 23 connected in the reverse series when the electric circuit is short-circuited changes depending on the circuit constant (capacitor capacity or the like). Then, by setting the circuit constant, the rise time of the current can be shortened and the current peak can be reduced.

Next, the waveform of the current flowing through the current-carrying coil 23 in the transient state of the current limiting device 100 will be described. In this fault current limiter 100, the current and the magnetic flux waveform at the timing of voltage application of the inrush current when the capacitance of the capacitor 25 was set to 250 μF, 300 μF, 400 μF, and 700 μF were observed, and the results are shown in FIGS. Shown in. From FIG. 11 to FIG. 14, the waveform of the current flowing through the energizing coil 23 connected in the reverse series at the time of short-circuiting the electric circuit has a peak value after passing through the region X-W in which the time change of the current is extremely small. It turns out that it becomes a waveform. Therefore, by interrupting the short-circuit current in the region X-W in which the time change of the current is extremely small, it becomes possible to interrupt the short-circuit current before the arc current suddenly increases due to the inrush current.

As described above, according to the first embodiment,
The secondary coils 24 respectively wound around the soft magnetic cores 21 constituting the first and second closed magnetic circuits are differentially connected, and both ends of both the secondary coils 24 are connected via a capacitor 25. ing. Therefore, the rise of the current flowing through the energizing coil 23 connected in the reverse series at the time of short-circuiting the electric path is shortened, the short-circuit current can be interrupted quickly in response to the electric-circuit short-circuit, and the current limiting response is improved. Further, the peak value of the current flowing through the energizing coil 23 connected in the reverse series is reduced, the arc current at the time of interruption can be reduced, and the interruption performance is improved. Further, the waveform of the current flowing through the current-carrying coil 23 at the time of a short circuit is a waveform having a region in which the time change of the current is very small, that is, a waveform that is easy to break, and the magnetic flux density of the soft magnetic core 21 is set high without lowering the breaking performance. You can
The current limiter can be miniaturized.

Further, the soft magnetic core 21 and the first to third cores 2
2a, 22b, 22c, first and second permanent magnets 20
Since the current limiting device 100 is composed of a, 20b, the energizing coil 23, the secondary coil 24, and the capacitor 25, there is no active means, and a highly reliable and maintenance-free current limiting device can be realized. Further, the elements 110A and 110B are
The second core 22b and the first permanent magnet 20a are connected to the soft magnetic core 21.
And the first core 22a and the third core 2a.
2c and the second permanent magnet 20b to the soft magnetic core 21 and the first
Since it is sandwiched between the other ends of the core 22a and the energizing coil 23 and the secondary coil 24 are wound so as to surround the soft magnetic core 21, the size of the current limiter 1 is reduced as compared with the conventional fault current limiter 1. -It is possible to reduce the weight.

In the first embodiment, the energizing coil 23 and the secondary coil 24 may be provided directly around the soft magnetic core 21 or may be provided via a bobbin. Further, in the first embodiment, the second and third yokes 22 are
b and 22c to the first and second permanent magnets 20a and 20b.
The first and second permanent magnets 20a and 20c are omitted by omitting the second and third yokes 22b and 22c. 20b may be sandwiched between both ends of the soft magnetic core 21 and the first yoke 22a.

In the first embodiment, the second and third yokes 22b and 22c are laminated on the first and second permanent magnets 20a and 20b to form the soft magnetic core 21 and the first yoke 2.
The second permanent magnet 20b is omitted, and the first permanent magnet 20a is sandwiched between one ends of the soft magnetic core 21 and the first yoke 22a.
The yoke having the same thickness as that of the first permanent magnet 20a is attached to the soft magnetic core 2
It may be sandwiched between the other end portions of the first yoke 22a and the first yoke 22a. Further, in the first embodiment, the secondary coil 24 differentially connected to the current limiter 6 shown in FIG. 23 is provided,
Although both ends of both the secondary coils 24 are connected through the capacitors 25, the conventional current limiter 1 is provided with the secondary coils 24 connected in a differential manner, and both ends of the both secondary coils 24 are connected to the capacitors. It goes without saying that it is also possible to connect via 25. Further, in the first embodiment, the current limiting device is manufactured based on the specifications of the coil and the core shown in FIGS. 3 and 4, but the specifications of the coil and the core of the current limiting device are the same as those of the current limiting device. It is appropriately set depending on the purpose of use.

Embodiment 2. FIG. 15 is a perspective view showing the configuration of a current limiting device according to Embodiment 2 of the present invention. Figure 15
In the first and second soft magnetic cores 3 for switching,
0a and 30b are made of the same material and have the same shape as the switching soft magnetic core 21 in the first embodiment, and are formed in a flat plate shape. The first permanent magnet 20a is sandwiched between one end portions and the first permanent magnet 20a is formed between the other end portions. The two permanent magnets 20b are sandwiched and arranged so as to face each other and are joined and integrated. The first and second energizing coils 31a and 31b are made of a low resistance material such as copper. The first energizing coil 31a is wound so as to surround the first soft magnetic core 30a, and the second energizing coil 31b is wound so as to surround the second soft magnetic core 30b. In addition, the first and second energizing coils 31a,
31b is connected to the reverse series. First and second
The secondary coils 32a and 32b are made of a low resistance material such as copper. Then, the first secondary coil 32a is wound so as to surround the first soft magnetic core 30a, and the second secondary coil 32a is wound so as to surround the second soft magnetic core 30b. There is. In addition, the first and second secondary coils 3
2a and 32b are differentially connected, and both ends thereof are connected via a capacitor 25.

In the magnetic switching type fault current limiter 100A constructed as described above, the first and second soft magnetic cores 30 are provided.
a, 30b and the first and second permanent magnets 20a, 20b
A single closed magnetic circuit including a first energizing coil 31a and a first secondary coil 32a wound around a first soft magnetic core 30a, a second energizing coil 31b and a second energizing coil 31b. Secondary coil 32b is wound around the second soft magnetic core 30b. Then, the first and second permanent magnets 20
a and 20b are the magnetization directions of the first and second soft magnetic cores 3.
Match the direction perpendicular to the surface where 0a and 30b are joined,
Moreover, they are magnetized so that they are in opposite directions. In addition, the first and second soft magnetic cores 30a and 30b are
And when the second energizing coils 31a and 31b are not energized,
The magnetic path cross-sectional area is formed so that the first and second permanent magnets 20a and 20b are magnetized to the magnetic saturation region.

Also in this fault current limiter 100A, since both ends of the first and second secondary coils 32a and 32b which are differentially connected are connected via the capacitor 25, the limiter according to the first embodiment is limited. It operates in the same manner as the sink 100, and similar effects can be obtained.

Further, according to the second embodiment, since the current limiter 100A is composed of a single closed magnetic circuit, the first yoke 22a is unnecessary and the number of permanent magnets is halved. The current limiter can be downsized and the price can be reduced.

In the second embodiment, the first and second permanent magnets 20a and 20b are sandwiched between the two ends of the first and second soft magnetic cores 30a and 30b, respectively. However, a yoke for expanding the gap is laminated on each of the first and second permanent magnets 20a and 20b,
The interval between the first and second soft magnetic cores 30a and 30B may be expanded. In this case, the yoke for expanding the gap is formed to have a larger magnetic path cross-sectional area than the first and second soft magnetic cores 30a and 30b.

Embodiment 3. In the magnetic switching type current limiting device 100A according to the second embodiment, the first permanent magnet 20a is connected to the first and second soft magnetic cores 30 for switching.
The second permanent magnet 20b is sandwiched between the ends of a and 30b.
The first and second switching soft magnetic cores 30a, 3
The magnetic switching type fault current limiter 100B according to the third embodiment has the first permanent magnet 20a with the first and second permanent magnets 20a. Switching soft magnetic cores 30a, 30
The yoke 33 having the same thickness as that of the first permanent magnet 20a is sandwiched between one ends of the first magnetic pole b and the other ends of the first and second soft magnetic cores 30a and 30b for switching. The yoke 33 is made of the same material as the first and second soft magnetic cores 30a and 30b, and has a larger magnetic path cross-sectional area than the first and second soft magnetic cores 30a and 30b. Note that other configurations are the same as those in the second embodiment.
Is configured similarly to.

Therefore, also in the third embodiment, the same operation as in the second embodiment is performed and the same effect is obtained. Further, according to the third embodiment, only one expensive permanent magnet is required, and the cost can be further reduced.

In the third embodiment, the first permanent magnet 20a is replaced by the first and second soft magnetic cores 30a and 30b.
, The yoke 33 is sandwiched between the other ends of the first and second soft magnetic cores 30a and 30b. However, the yoke for gap expansion is described as a first permanent magnet. 20a and the yoke 33 may be laminated respectively, and the interval between the first and second soft magnetic cores 30a and 30B may be expanded. In this case, the yoke for expanding the gap is formed to have a larger magnetic path cross-sectional area than the first and second soft magnetic cores 30a and 30b.

Fourth Embodiment In the magnetic switching type fault current limiter 100A according to the second embodiment, the first energizing coil 31a is wound around the first switching soft magnetic core 30a, and the second energizing coil 31b is wound around the second switching soft magnetic core. Although it is supposed to be wound around 30b, in the magnetic switching type current limiting device 100C according to the fourth embodiment,
As shown in FIG. 17, a current-carrying coil 34 made of a low-resistance material such as copper is wound so as to entirely surround the first and second soft magnetic cores 30a and 30b for switching. I am trying. The other configurations are the same as those in the second embodiment.

In the fourth embodiment, the energizing coil 34
However, since the first and second soft magnetic cores 30a and 30b, which are arranged to face each other with their magnetization directions being opposite to each other, are wound together, the first and second soft magnetic cores 30a are , 30b one saturation region A → the other saturation region C → the one saturation region A changes in the operating point of the magnetization acts on the energizing coil 34 every half cycle. Therefore, the single energizing coil 34 includes the first and second energizing coils 31 wound around the first and second soft magnetic cores 30a and 30b, respectively.
It is equivalent to connecting a and 31b in reverse series.

Therefore, also in the fourth embodiment, the same operation as in the second embodiment is performed and the same effect is obtained. Further, according to the fourth embodiment, the first and second
Of the energizing coil of the first and second soft magnetic cores 31a, 31
Since it is not necessary to wind around each of b, the assemblability of the current limiting device is improved.

Embodiment 5. In the magnetic switching type fault current limiter 100B according to the third embodiment, the first energizing coil 31a is wound around the first switching soft magnetic core 30a, and the second energizing coil 31b is wound around the second switching soft magnetic core. Although it is supposed to be wound around 30b, in the magnetic switching type current limiting device 100D according to the fifth embodiment,
As shown in FIG. 18, the energizing coil 34 is wound so as to collectively surround the first and second soft magnetic cores 30a and 30b for switching. The other configurations are the same as those in the third embodiment.

In the fifth embodiment as well, the single energizing coil 34 includes the first and second soft magnetic cores 30a, 30.
This is equivalent to connecting the first and second energizing coils 31a and 31b wound around each b in the reverse series, and operates in the same manner as in the third embodiment and obtains the same effect. According to the fifth embodiment, the first and second energizing coils are connected to the first and second soft magnetic cores 31a,
Since it is not necessary to wind each 31b, the assemblability of the current limiting device is improved.

Sixth Embodiment In the sixth embodiment, in the current limiting device 100 according to the first embodiment, the capacitor 25 is composed of a polar electrolytic capacitor. The rest of the configuration is the same as that of the first embodiment.

The polar electrolytic capacitor is smaller than the nonpolar capacitor for electric power used in the AC circuit.
The price can be reduced. However, in a polar electrolytic capacitor, when a high-voltage reverse voltage is applied, a rapid chemical conversion reaction occurs on the surface of the cathode foil, generating a large amount of heat and generating gas. This gas generation causes a problem that the explosion-proof valve of the electrolytic capacitor is activated and the electrolytic capacitor is destroyed, which limits the use of the electrolytic capacitor.

In the current limiter 100, the first embodiment described above is used.
As described in, the short-circuit current can be cut off immediately when a short circuit occurs. Therefore, the time during which the short-circuit current is applied to the capacitor at the time of short circuit is extremely short, such as several milliseconds or less. Furthermore, the frequency of short circuit accidents is extremely low. For this reason, even if an electrolytic capacitor is used as the capacitor 25, it is possible to prevent accidents such as damage and destruction of the electrolytic capacitor due to chemical conversion reaction. Therefore, according to the sixth embodiment, since the polar electrolytic capacitor is used as the capacitor 25, the size and cost of the device can be reduced.

In the sixth embodiment, an electrolytic capacitor is used as the capacitor 25 of the current limiting device according to the first embodiment, but an electrolytic capacitor is used as the capacitor of the current limiting device according to another embodiment. It goes without saying that it is okay.

In each of the above embodiments, the permanent magnet is described as being made of a rare earth magnet, but the permanent magnet is not limited to the rare earth magnet, and has a high coercive force and a high residual magnetic flux density. It has only to have, for example, a ferrite magnet (Ba system, Sr system), an extruded magnet (Mn-A).
1 series) and the like can be used. Further, in each of the above embodiments, the soft magnetic core is made of grain-oriented silicon steel, but the material of the soft magnetic core is not limited to grain-oriented silicon steel, and the soft magnetic material with good squareness is used. If
For example, permalloy (50% Fe-Ni), amorphous alloy or the like can be used.

[0057]

Since the present invention is constituted as described above, it has the following effects.

According to the present invention, the first and second closed magnetic circuits each including at least the soft magnetic core for switching and the permanent magnet and the soft magnetic core for switching which constitutes the first closed magnetic circuit are provided. A wound first energizing coil and a first secondary coil, and a second energizing coil and a second secondary wound around the switching soft magnetic core forming the second closed magnetic circuit. A secondary coil in which the first and second energizing coils are connected in reverse series, the first and second secondary coils are differentially connected, and the differentially connected Since the open end of is connected via a capacitor, the current limiting current at the time of a short circuit can be reduced, the rise time of the current limiting current can be shortened, and the current waveform of the current-carrying coil can be easily cut off. Profitable It is.

In each of the first and second closed magnetic circuits, the switching soft magnetic core and the first yoke are arranged to face each other, and the second yoke and the first permanent magnet are laminated. The soft magnetic core for switching and the first
It is sandwiched and joined between one end of the yoke and the third yoke and the second permanent magnet, and sandwiched and joined between the other end of the soft magnetic core for switching and the first yoke. The first and second permanent magnets are magnetized so that the magnetization directions thereof are orthogonal to the joint surface with the switching soft magnetic core and opposite to each other. The core is formed in a magnetic path cross-sectional area that is magnetically saturated by the first and second permanent magnets, and the first to third yokes are formed in a magnetic path cross-sectional area larger than that of the switching soft magnetic core. Therefore, it is possible to realize a current limiting device with a simple configuration that can reduce the current limiting current at the time of short circuit and shorten the rising time of the current limiting current.

In the first and second closed magnetic circuits, the first and second soft magnetic cores for switching are arranged to face each other, and the first permanent magnet is used for the first and second switching magnetic circuits. A single closed magnet which is sandwiched and joined between one ends of the soft magnetic core, and the second permanent magnet is sandwiched and joined between the other ends of the first and second soft magnetic cores for switching. Circuit, the first energizing coil and the first secondary coil are wound around the first soft magnetic core for switching, and the second energizing coil and the second secondary coil are The first and second permanent magnets are wound around a second soft magnetic core for switching, and the magnetization directions of the first and second permanent magnets are
The first and second soft magnetic cores for switching are magnetized so as to be orthogonal to the joint surface with the soft magnetic cores for switching and opposite to each other. Furthermore, the first and second soft magnetic cores for switching are Since it is formed in the magnetic path cross-sectional area that is magnetically saturated by the first and second permanent magnets, the current limiting current at the time of short circuit can be reduced and the rising time of the current limiting current can be shortened. Can be realized with a simple configuration,
Only one closed magnetic circuit is required, and further miniaturization and cost reduction can be achieved.

Further, in the first and second closed magnetic circuits, the first and second soft magnetic cores for switching are arranged to face each other, and the permanent magnets have the first and second soft magnetic cores for switching. A single closed magnetic circuit sandwiched and joined between one ends of the first and second soft magnetic cores for switching, and a yoke which is sandwiched and joined between the other ends of the first and second soft magnetic cores for switching. The first energizing coil and the first secondary coil are wound around the first switching soft magnetic core, and the second energizing coil and the second secondary coil are
The permanent magnet is wound around the second soft magnetic core for switching, and the permanent magnet is magnetized so that the magnetization direction is orthogonal to the joint surface with the first and second soft magnetic cores for switching.
The first and second soft magnetic cores for switching are formed in a magnetic path cross-sectional area that is magnetically saturated by the permanent magnets.
Further, since the yoke is formed with a magnetic path cross-sectional area larger than that of the first and second soft magnetic cores for switching, the current limiting current at the time of short circuit can be reduced and the rising time of the current limiting current can be reduced. A current limiter that can be shortened can be realized with a simple configuration, and only one closed magnetic circuit and one permanent magnet are required, and further downsizing and cost reduction can be achieved.

In the first and second closed magnetic circuits, the first and second soft magnetic cores for switching are arranged to face each other, and the first permanent magnet is used for the first and second switching magnetic circuits. A single closed magnet which is sandwiched and joined between one ends of the soft magnetic core, and the second permanent magnet is sandwiched and joined between the other ends of the first and second soft magnetic cores for switching. A first coil and a second coil, wherein the first and second energizing coils are constituted by a single coil formed by winding the first and second soft magnetic cores for switching so as to collectively surround them. The first secondary coil is wound around the first soft magnetic core for switching, the second secondary coil is wound around the second soft magnetic core for switching, and the first and second soft magnetic cores are wound. Of the permanent magnet of the first and second magnets Perpendicular to the junction surface of the etching for the soft magnetic core, and is magnetized so as to opposite to each other,
Furthermore, since the first and second soft magnetic cores for switching are formed in the magnetic path cross-sectional area that is magnetically saturated by the first and second permanent magnets, the current limiting current at the time of short circuit can be reduced. In addition, it is possible to realize a current limiting device that can shorten the rising time of the current limiting current with a simple configuration, and a single closed magnetic circuit and a current-carrying coil are required, further downsizing,
The price can be reduced.

In the first and second closed magnetic circuits, the first and second switching soft magnetic cores are arranged so as to face each other, and the permanent magnets include the first and second switching soft magnetic cores. A single closed magnetic circuit sandwiched and joined between one ends of the first and second soft magnetic cores for switching, and a yoke which is sandwiched and joined between the other ends of the first and second soft magnetic cores for switching. The first and second energizing coils are constituted by a single coil formed by winding the first and second soft magnetic cores for switching so as to surround them collectively, and the first secondary coil is The first soft magnetic core for switching is wound around, the second secondary coil is wound around the second soft magnetic core for switching, and the permanent magnet has a magnetizing direction of the first and second soft magnetic cores. Joint surface with second soft magnetic core for switching The first and second soft magnetic cores for switching, which are magnetized so as to be orthogonal to each other, are formed in a magnetic path cross-sectional area that is magnetically saturated by the permanent magnets, and further, the yoke includes the first and second soft magnetic cores. Since it is formed with a larger magnetic path cross-sectional area than the switching soft magnetic core, it is possible to realize a current limiting device with a simple configuration that can reduce the current limiting current at the time of a short circuit and shorten the rising time of the current limiting current. At the same time, a closed magnetic circuit, a current-carrying coil and a permanent magnet are all required in one unit, and further miniaturization and cost reduction can be achieved.

Further, since the above-mentioned capacitor is a polar electric field capacitor, the size and cost of the device can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a current limiting device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of the current limiting device according to the first embodiment of the present invention.

FIG. 3 is a diagram showing coil specifications in the current limiting device according to the first embodiment of the present invention.

FIG. 4 is a diagram showing core specifications in the current limiting device according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a voltage waveform induced in the entire secondary coil (secondary coil open) differentially connected when a short circuit occurs in the current limiting device according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a voltage waveform induced in the entire secondary coil (secondary coil open) connected in the reverse series at the time of a short circuit in the current limiting device according to the first embodiment of the present invention.

FIG. 7 is a diagram showing a steady-state current waveform induced in the secondary coil of the differential connection in which the capacitors are connected at the time of short circuit in the current limiting device according to the first embodiment of the present invention.

FIG. 8 is a diagram showing a steady-state current waveform flowing through the entire energizing coils (secondary coil open) connected in the reverse series at the time of a short circuit in the current limiting device according to the first embodiment of the present invention.

FIG. 9 is connected to the reverse series in the steady state at the time of short circuit of the current limiting device (the secondary coil differentially connected is connected via a capacitor (200 μF)) according to the first embodiment of the present invention. It is a figure which shows the current waveform which flows into the whole energization coil, and the magnetic flux waveform of a soft magnetic core.

FIG. 10 is connected to a reverse series in a steady state at the time of short circuit of the current limiting device (the secondary coil differentially connected is connected via a capacitor (400 μF)) according to the first embodiment of the present invention. It is a figure which shows the current waveform which flows into the whole energization coil, and the magnetic flux waveform of a soft magnetic core.

FIG. 11 is connected to the reverse series at the time of a transient at the time of short circuit of the current limiting device (the secondary coil differentially connected is connected via a capacitor (250 μF)) according to the first embodiment of the present invention. It is a figure which shows the current waveform which flows into the whole energization coil, and the magnetic flux waveform of a soft magnetic core.

FIG. 12 is connected to the reverse series at the time of a transient at the time of short circuit of the current limiting device (the secondary coil differentially connected is connected via a capacitor (300 μF)) according to the first embodiment of the present invention. It is a figure which shows the current waveform which flows into the whole energization coil, and the magnetic flux waveform of a soft magnetic core.

FIG. 13 is connected to the reverse series at the time of transient at the time of short circuit of the current limiting device (the secondary coil connected differentially is connected via a capacitor (400 μF)) according to the first embodiment of the present invention. It is a figure which shows the current waveform which flows into the whole energization coil, and the magnetic flux waveform of a soft magnetic core.

FIG. 14 is connected to the reverse series at the time of a transient at the time of short circuit of the current limiting device (the secondary coil connected differentially is connected via a capacitor (700 μF)) according to the first embodiment of the present invention. It is a figure which shows the current waveform which flows into the whole energization coil, and the magnetic flux waveform of a soft magnetic core.

FIG. 15 is a perspective view showing a configuration of a current limiting device according to a second embodiment of the present invention.

FIG. 16 is a perspective view showing a configuration of a current limiting device according to a third embodiment of the present invention.

FIG. 17 is a perspective view showing a configuration of a current limiting device according to a fourth embodiment of the present invention.

FIG. 18 is a perspective view showing a configuration of a current limiting device according to a fifth embodiment of the present invention.

FIG. 19 is a schematic diagram showing a configuration of a conventional magnetic switching type fault current limiter.

FIG. 20 is a magnetic flux-current diagram for explaining a magnetic operation of a conventional magnetic switching type fault current limiter.

FIG. 21 is an electric circuit diagram in which a conventional magnetic switching type fault current limiter is incorporated.

FIG. 22 is an LR series circuit for explaining a transient phenomenon of a conventional magnetic switching type fault current limiter.

FIG. 23 is a perspective view showing the configuration of a magnetic switching type fault current limiter model devised by the present applicant.

FIG. 24 is a diagram showing transient phenomenon waveforms of an energized current and a magnetic flux of a magnetic core during a short circuit in the magnetic switching type fault current limiter model shown in FIG. 23.

[Explanation of symbols]

20a 1st permanent magnet, 20b 2nd permanent magnet, 2
1 soft magnetic core for switching, 22a first yoke, 2
2b 2nd yoke, 22c 3rd yoke, 23 energizing coil, 24 secondary coil, 25 capacitor, 30a 1st switching soft magnetic core, 30b 2nd switching soft magnetic core, 31a 1st energizing coil, 31b
Second energizing coil, 32a first secondary coil, 32b
Second secondary coil, 33 yoke, 34 energizing coil, 100, 100A, 100B, 100C, 100D
Current limiter.

Claims (7)

[Claims] 1. A first and second closed magnetic circuit, which comprises at least a soft magnetic core for switching and a permanent magnet, and a soft magnetic core for switching, which is wound around the first soft magnetic core. First energizing coil and first
Secondary coil, a second energizing coil and a second secondary coil wound around the switching soft magnetic core forming the second closed magnetic circuit, and the first and second The energizing coils are connected in reverse series, the first and second secondary coils are differentially connected, and the open ends of the differentially connected secondary coils are connected via a capacitor. A current limiting device characterized by that. 2. In each of the first and second closed magnetic circuits, the soft magnetic core for switching and the first yoke are arranged to face each other, and the second yoke and the first permanent magnet are laminated. The switching soft magnetic core and the first yoke are sandwiched and joined between one ends of the soft magnetic core and the first yoke, and the third yoke and the second permanent magnet are stacked to form the soft magnetic core for switching and the first yoke. The first and second permanent magnets are sandwiched and bonded between the other ends, and the magnetization directions of the first and second permanent magnets are orthogonal to the bonding surface with the soft magnetic core for switching and opposite to each other. And the soft magnetic core for switching is formed in a magnetic path cross-sectional area which is magnetically saturated by the first and second permanent magnets, and the first to third yokes are soft magnetic for switching. Magnetic path larger than magnetic core The current limiting device according to claim 1, wherein the current limiting device is formed in a cross-sectional area. 3. The first and second closed magnetic circuits are arranged such that first and second soft magnetic cores for switching face each other, and a first permanent magnet is used for the first and second switching magnetic circuits. A single closed magnet which is sandwiched and joined between one ends of the soft magnetic core, and the second permanent magnet is sandwiched and joined between the other ends of the first and second soft magnetic cores for switching. Circuit, the first energizing coil and the first secondary coil are wound around the first switching soft magnetic core, and the second energizing coil and the second secondary coil are It is wound around a second soft magnetic core for switching, and the first and second permanent magnets have a magnetization direction orthogonal to the joint surface with the soft magnetic core for switching, and The magnets are magnetized so as to be opposite to each other. Beauty second switching soft magnetic core, current limiting device according to claim 1, characterized in that it is formed in the magnetic path cross-sectional area that is magnetically saturated by the first and second permanent magnets. 4. The first and second closed magnetic circuits are arranged such that first and second soft magnetic cores for switching face each other, and permanent magnets have the first and second soft magnetic cores for switching. A single closed magnetic circuit sandwiched and joined between one ends of the first and second soft magnetic cores for switching, and a single closed magnetic circuit formed by sandwiching and joined between the other ends of the first and second soft magnetic cores for switching. The first energizing coil and the first secondary coil are wound around the first switching soft magnetic core, and the second energizing coil and the second secondary coil are the second switching soft magnetic core. The permanent magnet is wound around a core, and the permanent magnet is magnetized so that the magnetization direction is orthogonal to the joint surface with the first and second switching soft magnetic cores, and the first and second switching soft magnets are magnetized. The magnetic core is magnetically saturated by the permanent magnet. 2. The current limiting section according to claim 1, wherein the yoke has a magnetic path cross-sectional area larger than that of the first and second soft magnetic cores for switching. vessel. 5. The first and second closed magnetic circuits are arranged such that first and second soft magnetic cores for switching face each other, and a first permanent magnet is used for the first and second switching magnetic circuits. A single closed magnet which is sandwiched and joined between one ends of the soft magnetic core, and the second permanent magnet is sandwiched and joined between the other ends of the first and second soft magnetic cores for switching. A first coil, and the first and second energizing coils are constituted by a single coil formed by winding the first and second soft magnetic cores for switching so as to collectively surround them. The first secondary coil is wound around the first soft magnetic core for switching, the second secondary coil is wound around the second soft magnetic core for switching, and the first and second soft magnetic cores are wound. Of the permanent magnet of the first and second switches. Magnetized so as to be orthogonal to the joining surface with the soft magnetic core for switching and opposite to each other. Furthermore, the first and second soft magnetic cores for switching have the first and second permanent magnets. The current limiting device according to claim 1, wherein the current limiting device is formed in a magnetic path cross-sectional area that is magnetically saturated by a magnet. 6. The first and second closed magnetic circuits are arranged such that first and second soft magnetic cores for switching are opposed to each other, and permanent magnets are soft magnetic cores for first and second switching. A single closed magnetic circuit sandwiched and joined between one ends of the first and second soft magnetic cores for switching, and the yoke is sandwiched and joined between the other ends of the first and second soft magnetic cores for switching. The first and second energizing coils are constituted by a single coil formed by winding the first and second soft magnetic cores for switching so as to surround them collectively, and the first secondary coil is The first soft magnetic core for switching is wound, the second secondary coil is wound on the second soft magnetic core for switching, and the permanent magnet has a magnetizing direction of the first and second soft magnetic cores. On the joint surface with the second soft magnetic core for switching The first and second soft magnetic cores for switching are magnetized so as to intersect with each other, and are formed in a magnetic path cross-sectional area that is magnetically saturated by the permanent magnets. Further, the yoke includes the first and second soft magnetic cores. 2. The current limiter according to claim 1, wherein the current limiter has a larger magnetic path cross-sectional area than the switching soft magnetic core. 7. The fault current limiter according to claim 1, wherein the capacitor is a polar electric field capacitor.