WO2018128149A1

WO2018128149A1 - Core, and reactor, current limiter, electromagnetic actuator and motor using said core

Info

Publication number: WO2018128149A1
Application number: PCT/JP2017/046982
Authority: WO
Inventors: 佐藤　卓; 研松浦
Original assignee: Tdk株式会社
Priority date: 2017-01-05
Filing date: 2017-12-27
Publication date: 2018-07-12
Also published as: JP7127545B2; JPWO2018128149A1

Abstract

[Problem] To provide a core that can be widely applied, e.g., in a reactor, current limiter, electromagnetic actuator, motor, etc. [Solution] The magnetic characteristics of this core 11 are such that, in a first quadrant of a graph with the magnetic field as the first axis and magnetic flux density or magnetization as the second axis, in a first magnetic field region MF1 with an intensity less than or equal to a first magnetic field intensity H1, the differential value of the magnetic flux density or magnetization with respect to the magnetic field is a first value, and in a second magnetic field region MF2 with an intensity greater than the first magnetic field intensity H1, the differential value of the magnetic flux density or magnetization with respect to the magnetic field is a second value greater than the first value. According to the present invention, a smaller magnetization is obtained in the first magnetic field region with the lower magnetic field intensity, and a greater magnetization is obtained in the second magnetic field region with the high magnetic field intensity. For this reason, if the magnetic field intensity changes from the first magnetic field region to the second magnetic field region, since magnetization increases rapidly, the core can be applied to various devices that utilize this phenomenon, such as a reactor, a current limiter, an electromagnetic actuator or a motor.

Description

Magnetic core and reactor, current limiter, electromagnetic actuator and motor using the same

The present invention relates to a magnetic core and a reactor, a current limiter, an electromagnetic actuator, and a motor using the magnetic core.

Reactors in which a coil is wound around a magnetic core are used for various purposes such as current limiters. Magnetic cores are also widely used for electromagnetic actuators and motors. Hereinafter, the current limiter will be described.

When a short circuit accident occurs in a power system or an electric circuit, a large current flows instantaneously at the short circuit point, and this current may damage system devices and circuit elements, or may cause a fire. Conventionally, a current limiter is known as a device for suppressing such a large current when a short circuit accident occurs. The demand for current limiters is expected to increase in the future with the increase in power capacity and the spread of distributed power sources in recent years.

The specific configuration of the current limiting device is described in Patent Documents 1 to 4, for example. The current limiting device described in Patent Documents 1 and 2 has a configuration in which a reactor is connected to a bridge circuit composed of a thyristor and a diode. The current limiter described in Patent Document 3 has a configuration in which a series resonant circuit and a parallel resonant circuit are combined. Furthermore, the current limiting device described in Patent Document 4 has a configuration in which a magnetic bias is applied to a saturable DC reactor using a DC power supply.

JP 49-50448 A Japanese Patent Laid-Open No. 9-285012 JP 2010-17016 A JP 2002-291150 A Japanese Patent No. 6109453 Japanese Patent Laid-Open No. 2015-220797

However, the current limiters described in Patent Documents 1 to 4 have a large number of elements and a complicated apparatus configuration. In particular, the current limiting device described in Patent Document 3 requires a separate filter circuit for suppressing noise, which further complicates the circuit configuration. In addition, the current limiter described in Patent Document 4 always requires a DC power source for applying a magnetic bias, and there is a problem that it does not function as a current limiter when the DC power source is lost.

As described above, since the conventional current limiter has a complicated device configuration, there is a problem that not only it is difficult to ensure reliability but also a heavy maintenance burden. Moreover, it is difficult to obtain a sufficient response speed due to the complexity of the device configuration.

Further, Patent Document 5 discloses an electromagnetic actuator that interrupts a current path when a large current is generated. The electromagnetic actuator described in Patent Document 5 includes a movable iron core and a stationary iron core, and a tripping conductor (coil) through which a main circuit current flows. By fixing the end of the movable iron core with a return spring, a large current is generated. It is configured to perform only the shut-off operation. However, the electromagnetic actuator described in Patent Document 5 has a problem in reliability due to not only a slow response speed but also aged deterioration of the spring because the response current for performing the breaking operation is determined by the spring characteristics.

Furthermore, although not an electromagnetic actuator using a coil, Patent Document 6 discloses an actuator using a metamagnetic material. However, since the actuator described in Patent Document 6 uses a magnetic phase transition due to temperature, it requires rapid heating and cooling, and has a problem that the application range is very limited.

Also, a general motor using a soft magnetic material for the rotor or stator has a problem that cogging torque is generated.

Therefore, one object of the present invention is to provide a magnetic core that can be widely applied to reactors, current limiters, electromagnetic actuators, motors, and the like.

Another object of the present invention is to provide a highly reliable reactance type current limiter having a simple device configuration.

Still another object of the present invention is to provide an electromagnetic actuator having a high response speed and high reliability.

Still another object of the present invention is to provide a motor with reduced cogging torque.

The magnetic core according to the present invention has a magnetic property in which magnetic flux is applied to a magnetic field in a first magnetic field region below a first magnetic field strength in a first quadrant of a graph in which a first axis is a magnetic field and a second axis is a magnetic flux density or magnetization. In a second magnetic field region in which a differential value of density or magnetization is a first value and the magnetic field intensity is higher than the first magnetic field strength, a second magnetic flux density or magnetization differential value with respect to the magnetic field is larger than the first value. It is the value of.

According to the present invention, the first magnetic field region with a low magnetic field strength behaves as a non-magnetic material without magnetization, and the second magnetic field region with a high magnetic field strength behaves as a ferromagnetic material with magnetization. For this reason, when the magnetic field intensity changes from the first magnetic field region to the second magnetic field region, the magnetization rapidly increases. Therefore, various devices such as a reactor, a current limiter, an electromagnetic actuator, and a motor using this phenomenon. It becomes possible to apply to.

For example, if a reactor is configured by winding a coil around a magnetic core according to the present invention and this is applied to a current limiter, the current operates in the first magnetic field region when the current flowing through the coil is a predetermined value or less. For this reason, while the reactance is small, when the current flowing through the coil exceeds a predetermined value, the reactance increases because it operates in the second magnetic field region. As a result, when the current is less than or equal to the predetermined value, the current limiting operation can be performed when the current exceeds the predetermined value without substantially becoming a load on the power system or the electric circuit. And since it is the simple apparatus structure which wound the coil around the magnetic core, it becomes possible to provide a low-cost and highly reliable current limiter.

The magnetic core according to the present invention can also be applied to an electromagnetic actuator. In this case, a fixed magnetic core, a movable magnetic core, and a coil wound around at least one of the fixed magnetic core and the movable magnetic core are provided, and the magnetic core according to the present invention is used for at least one of the fixed magnetic core and the movable magnetic core. good. According to this, it is possible to provide an electromagnetic actuator having a high response speed and high reliability.

Furthermore, the magnetic core according to the present invention can be applied to a motor. In this case, a rotor and a stator are provided, and the magnetic core according to the present invention may be used for at least one of the rotor and the stator. According to this, it becomes possible to provide a motor with reduced cogging torque.

In the present invention, the magnetic characteristic of the magnetic core is a third value in which the magnetic flux density with respect to the magnetic field or the differential value of the magnetization is smaller than the second value in the third magnetic field region that is stronger than the second magnetic field strength. It does not matter. Even when a magnetic core having such a magnetic characteristic is used for, for example, a current limiter, a large reactance is generated when the current flowing through the coil exceeds a predetermined value, so that the current limiter functions correctly. Examples of materials exhibiting such magnetic characteristics include metamagnetic materials, perminbar characteristic materials, and synthetic antiferromagnetic materials. In particular, when a metamagnetic material is used, it is preferable to use an antiferromagnetic ferromagnetic transition material that transitions from antiferromagnetism to ferromagnetism depending on the magnetic field strength. According to this, it becomes possible to use in a wide temperature range including normal temperature.

In the present invention, it is preferable that the characteristic curve indicating the magnetic characteristic of the magnetic core substantially passes through the origin of the graph. If a material having no hysteresis or having a very small hysteresis is used, for example, a current limiter or an electromagnetic actuator can be stably operated over a plurality of times.

Thus, according to the present invention, it is possible to provide a magnetic core that can be widely applied to reactors, current limiters, electromagnetic actuators, motors, and the like.

In addition, according to the present invention, a highly reliable reactance type current limiter having a simple device configuration, a fast response speed and high reliability electromagnetic actuator, and a motor with reduced cogging torque are provided. It becomes possible to do.

FIG. 1 is a circuit diagram of an electric circuit using a current limiter 10 according to the first embodiment of the present invention. FIG. 2 is another circuit diagram of an electric circuit using the current limiting device 10. FIG. 3 is still another circuit diagram of an electric circuit using the current limiting device 10. FIG. 4 is a diagram illustrating an example of a specific configuration of the current limiter 10. FIG. 5 is a graph showing the magnetic characteristics of the magnetic material used for the magnetic core 11. FIG. 6 is a graph showing the magnetic properties of the magnetic material used for the magnetic core 11 and shows only the first quadrant (I). FIG. 7 is a graph showing the relationship between the current I flowing through the coil 12 of the current limiter 10 and the inductance L. FIG. 8 is a graph showing the relationship between the voltage V applied to the coil 12 and the current I flowing through the coil 12. FIG. 9 is another graph showing the magnetic characteristics of the magnetic material used for the magnetic core 11. FIG. 10 is a graph showing the differential values of the characteristics shown in FIG. FIG. 11 is a graph showing the twice differential value of the characteristic shown in FIG. FIG. 12 is a graph showing the relationship between the current I flowing through the coil 12 and the value of B / H. FIG. 13 is a schematic diagram for explaining the configuration of the electromagnetic actuator 60 according to the second embodiment of the present invention. FIG. 14 is a schematic diagram for explaining a configuration of a motor 70 according to the third embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a circuit diagram of an electric circuit using a current limiter 10 according to the first embodiment of the present invention.

1 includes a current limiter 10 and a load 30 connected in series to an AC power source 20. The AC power source 20 is, for example, a commercial power source, and the load 30 is various electric devices that operate with power supplied from the AC power source 20. The current limiter 10 according to the present embodiment is connected in series between the AC power supply 20 and the load 30 and plays a role of suppressing a large current that flows when the load 30 causes a short circuit accident. As shown in FIG. 2, the circuit breaker 40 may be connected in series with the load 30. If the circuit breaker 40 is used, when the load 30 causes a short circuit accident, the circuit breaker 40 can perform a circuit breaking operation in a state where a large current is suppressed by the current limiter 10.

As shown in FIGS. 1 and 2, the current limiter 10 according to the present embodiment is a simple reactor. Although details will be described later, the reactance of the current limiter 10 is sufficiently small during normal operation when the current I is equal to or less than a predetermined value, and thus the impedance given to the electric circuit is very small. On the other hand, when the current I exceeds a predetermined value, the reactance of the current limiter 10 is significantly increased. Thereby, since it acts as a large impedance for the AC power supply 20, an increase in the current I is suppressed. Such a change in reactance is due to a change in the magnetic field applied to the magnetic core of the reactor (the principle of electromagnetic induction) and occurs spontaneously in response to a change in the current I. Therefore, an element for detecting the current value Etc. are not necessary.

In order to further reduce the voltage drop caused by the reactance component during normal operation, a capacitor 50 that resonates with the current limiter 10 may be connected in series as shown in FIG. If the resonance frequency of the resonance circuit including the current limiter 10 and the capacitor 50 is matched with the frequency of the AC power supply 20, the impedance of the current limiter 10 during normal operation can be greatly reduced.

In addition, since the current limiter 10 according to the present embodiment is a reactor type, application to an AC circuit is suitable. However, since reactance has an action of delaying an increase in current, assuming that the circuit breaker 40 that cuts off a large current is used, the current limiter 10 according to the present embodiment is used in a DC circuit. However, it is possible to reduce the risk of exceeding the breaking capacity of the breaker 40 (maximum power value that can be cut off). Therefore, the current limiter 10 according to the present embodiment can also be used for a DC circuit.

FIG. 4 is a diagram illustrating an example of a specific configuration of the current limiter 10 according to the present embodiment.

4 includes a toroidal magnetic core 11 and a coil 12 wound around the magnetic core 11. The current limiting device 10 shown in FIG. The coil 12 is preferably made of a coated conductor using copper (Cu) having a low resistance value as a core material. The toroidal magnetic core 11 forms a closed magnetic circuit. When a current I flows through the coil 12 wound around the magnetic core 11, a magnetic flux that circulates around the toroidal magnetic core 11 is generated. However, during normal operation where the current I is less than or equal to a predetermined value, the magnetic permeability of the magnetic core 11 is sufficiently low, and therefore the reactance generated is small. When the current I exceeds the predetermined value, the magnetic permeability of the magnetic core 11 increases abruptly, and the reactance also increases abruptly.

In order to express such a phenomenon, in this embodiment, the magnetic material described in detail below is used as the material of the magnetic core 11.

FIG. 5 is a graph showing the magnetic characteristics of the magnetic material used for the magnetic core 11, wherein the horizontal axis (X axis) as the first axis represents the magnetic field H, and the vertical axis (Y axis) as the second axis represents the magnetization. M is shown. In FIG. 5, symbol A indicates the magnetic property of the magnetic core 11, symbol SM indicates the magnetic property of a general soft magnetic material, and symbol HM indicates the magnetic property of a general hard magnetic material.

As shown by the symbol SM in FIG. 5, a general soft magnetic material has a high magnetic permeability in a low magnetic field region and is easily magnetized. On the other hand, when the magnetic field strength exceeds a predetermined value, magnetic saturation occurs. It shows the property of being hardly magnetized. In other words, the differential value of the magnetization M with respect to the magnetic field H is large in the magnetic field region where the magnetic saturation is not performed, and the differential value of the magnetization M with respect to the magnetic field H is small in the magnetic field region where the magnetic saturation occurs. In addition, since a general soft magnetic material has no hysteresis or very small hysteresis, the characteristic curve indicated by symbol SM passes through the graph origin or the vicinity thereof. Therefore, the characteristic curve indicated by symbol SM appears in the first quadrant (I) and the third quadrant (III) of the graph, and does not substantially appear in the second quadrant (II) and the fourth quadrant (IV).

As shown by symbol HM in FIG. 5, a general hard magnetic material has a large hysteresis, and a magnetized state is maintained even if the magnetic field is zero. For this reason, the characteristic curve indicated by symbol HM appears in all of the first quadrant (I) to the fourth quadrant (IV) of the graph.

In contrast to these general ferromagnetic materials, the magnetic material used for the magnetic core 11 in the present embodiment is in the low magnetic field region as indicated by symbol A in the first quadrant (I) and the third quadrant (III) of the graph. Is hardly magnetized because of its low magnetic permeability, and is easily magnetized with a high magnetic permeability in the intermediate magnetic field region, and further exhibits magnetic saturation when it enters the strong magnetic field region, and hardly magnetizes beyond that. Depending on the material selected, there is a slight hysteresis in the first quadrant (I) and the third quadrant (III), but since the residual magnetization is zero or very small, the characteristic curve indicated by the symbol A is substantially a graph. Pass through the origin. Even when the characteristic curve indicated by the symbol A does not strictly pass through the origin of the graph, it passes through the vicinity of the origin on the horizontal axis or the vertical axis. This means that the same magnetic characteristics can be obtained regardless of whether the magnetic material is in the initial state or after being repeatedly applied with a magnetic field. For this reason, the current limiter 10 using the magnetic material can be used repeatedly, and is automatically restored after the current limiting operation is completed.

FIG. 6 is a graph showing the magnetic characteristics of the magnetic material used for the magnetic core 11 and shows only the first quadrant (I).

More specifically, the magnetic characteristics of the magnetic core 11 will be described with reference to FIG. 6. When the magnetic field is increased from the state without the magnetic field H, the region up to the first magnetic field strength H1 (first magnetic field region MF1) is obtained. The permeability is low, so that the increase in magnetization M is slight. The slope of the graph, that is, the differential value of the magnetization M with respect to the magnetic field H is linked to the magnetic permeability. The magnetic permeability in the first magnetic field region MF1 is substantially the same as the magnetic permeability of the nonmagnetic material. Therefore, the first magnetic field region MF1 substantially behaves as a nonmagnetic material.

On the other hand, in the region from the first magnetic field strength H1 to the second magnetic field strength H2 (second magnetic field region MF2), the magnetic permeability increases rapidly, and the value of the magnetization M increases significantly. That is, as the magnetic field is increased, the magnetic permeability rapidly increases with the first magnetic field strength H1 as a boundary. The magnetic permeability in the second magnetic field region MF2 is close to the magnetic permeability of the soft magnetic material, and therefore behaves softly in the second magnetic field region MF2.

When the second magnetic field strength H2 is exceeded by further increasing the magnetic field (third magnetic field region MF3), magnetic saturation occurs, and the slope of the graph, that is, the magnetic permeability, decreases again.

Conversely, when the magnetic field is weakened from the third magnetic field region MF3 and falls below the third magnetic field strength H3, the magnetic permeability increases again in the region up to the fourth magnetic field strength H4. And if it falls below 4th magnetic field intensity | strength H4, magnetic permeability will fall and it will behave as a nonmagnetic material again. Thus, although there is hysteresis in the first quadrant (I), there is almost no residual magnetization. Therefore, once the magnetic field H is returned to near zero, the same characteristics as described above can be obtained again.

The magnetic material constituting the magnetic core 11 is not particularly limited as long as it is a magnetic material having the above-described magnetic characteristics, and examples thereof include metamagnetic materials, perminbar characteristic materials, and synthetic antiferromagnetic materials. The magnetic material constituting the magnetic core 11 may be a single substance of a metamagnetic material, a permember characteristic material, or a synthetic antiferromagnetic material, or a combination thereof, and a part of the magnetic core 11 is made of a ferromagnetic material. It does not matter.

If the magnetic core 11 is made of such a magnetic material, the inductance can be changed greatly depending on the magnitude of the current I flowing through the coil 12 of the current limiter 10. Here, the magnetic field H applied to the magnetic core 11 is determined by the structure of the coil 12 and the current I flowing through the coil 12, and when the magnetic path length is ML and the number of turns of the coil 12 is N,
H = N × I / ML
Defined by

FIG. 7 is a graph showing the relationship between the current I flowing through the coil 12 of the current limiter 10 and the inductance L. Here, the current value I1 shown in FIG. 7 is a current value at which the magnetic field H applied to the magnetic core 11 becomes the first magnetic field strength H1. Further, the current value I2 shown in FIG. 7 is a current value at which the magnetic field H applied to the magnetic core 11 becomes the second magnetic field strength H2.

As shown in FIG. 7, if the current I flowing through the coil 12 is equal to or less than the first current value I1, the value of the inductance of the current limiter 10 is L1, which is sufficiently low. This is because when the current I flowing through the coil 12 is equal to or less than the first current value I1, the magnetic core 11 is in the first magnetic field region MF1 and the magnetic permeability is sufficiently low. As a result, the current limiter 10 hardly becomes a load on the electric circuit. Here, when the magnetic permeability of the magnetic core 11 in the first magnetic field region MF1 is μ1, and the cross-sectional area of the magnetic core 11 is S, the inductance L1 in the first magnetic field region MF1 is
L1 = μ1 × N ² × S / ML
Defined by

On the other hand, when the current I flowing through the coil 12 exceeds the first current value I1, the value of the inductance of the current limiter 10 rapidly increases to L2 (> L1). This is because when the current I flowing through the coil 12 exceeds the first current value I1, the magnetic core 11 becomes the second magnetic field region MF2, and thus the magnetic permeability rapidly increases. The first current value I1 is an operation start point of the current limiter 10, and when the current I flowing through the coil 12 exceeds the first current value I1, the inductance of the current limiter 10 rapidly increases. As a result, when a current exceeding the first current value I1 flows in the electric circuit, the current limiter 10 spontaneously starts a current limiting operation. Here, when the magnetic permeability of the magnetic core 11 in the second magnetic field region MF2 is μ2, the inductance L2 in the second magnetic field region MF2 is:
L2 = μ2 × N ² × S / ML
Defined by

Then, when the current I flowing through the coil 12 exceeds the second current value I2, the value of the inductance of the current limiter 10 rapidly decreases to L3 (<L2). This is because the magnetic core 11 becomes the third magnetic field region MF3 when the current I flowing through the coil 12 exceeds the second current value I2.

FIG. 8 is a graph showing the relationship between the voltage V applied to the coil 12 and the current I flowing through the coil 12. In the graph shown in FIG. 8, when the current I flowing through the coil 12 is less than or equal to the first current value I1, the impedance Z1 indicated by the slope of the graph is low, and the current I flowing through the coil 12 has the first current value I1. Exceeding this indicates that the impedance Z2 increases.

Thus, in the current limiter 10 according to the present embodiment, since the magnetic core 11 has the magnetic characteristics shown in FIGS. 5 and 6, the current I flowing through the coil 12 is not more than the first current value I1. In some cases, the load is hardly loaded. On the other hand, when the current I flowing through the coil 12 exceeds the first current value I1, a current limiting operation can be performed due to a rapid increase in inductance. In the graphs shown in FIGS. 5 and 6, the vertical axis is the magnetization M, but the same relationship can be established even if the vertical axis is replaced with the magnetic flux density B.

FIG. 9 is another graph showing the magnetic characteristics of the magnetic material used for the magnetic core 11. The horizontal axis as the first axis shows the magnetic field H, and the vertical axis as the second axis shows the magnetic flux density B. .

As shown in FIG. 9, even when the vertical axis is replaced with the magnetic flux density B, the magnetic characteristic of the magnetic core 11 draws a similar characteristic curve in the first quadrant (I) of the graph. That is, the inclination is small in the first magnetic field region MF1 that is a low magnetic field, the inclination is rapidly increased in the second magnetic field region MF2 that is a medium magnetic field, and the inclination is large in the third magnetic field region MF3 that is a strong magnetic field. Becomes smaller again. Also in the graph shown in FIG. 9, the characteristic curve indicating the magnetic characteristics of the magnetic core 11 substantially passes through the origin, and even if it does not pass through the origin of the graph strictly, the horizontal axis or the vicinity of the origin on the vertical axis Pass through.

FIG. 10 is a graph showing the differential value of the characteristic shown in FIG. 9, and FIG. 11 is a graph showing the double differential value of the characteristic shown in FIG. The characteristics shown in FIG. 10 correspond to the differential permeability of the magnetic material constituting the magnetic core 11.

As shown in FIG. 10, when the characteristic shown in FIG. 9 is differentiated once, the differential value becomes maximum in the second magnetic field region MF2. In the first magnetic field region MF1 and the third magnetic field region MF3, the differential value remains small. Then, as shown in FIG. 11, when the characteristic shown in FIG. 9 is differentiated twice, the twice differentiated value is inverted from a positive value to a negative value in the second magnetic field region MF2. In the first magnetic field region MF1 and the third magnetic field region MF3, the twice differential value is almost zero. Thus, the magnetic material used for the magnetic core 11 has a characteristic that when the magnetic flux density B is differentiated twice with respect to the magnetic field H, the twice-differentiated value is inverted from a positive value to a negative value.

FIG. 12 is a graph showing the relationship between the current I flowing through the coil 12 and the value of B / H. The value of B / H corresponds to the average magnetic permeability.

As shown in FIG. 12, when the current I flowing through the coil 12 is less than or equal to the first current value I1, the value of B / H (average magnetic permeability) is low and there is almost no change in the electric circuit. Has little effect on. On the other hand, when the current I flowing through the coil 12 exceeds the first current value I1, the value of B / H (average magnetic permeability) increases rapidly. Thereafter, when the current I flowing through the coil 12 exceeds the second current value I2, the value of B / H (average magnetic permeability) gradually decreases. This is because the magnetic core 11 is magnetically saturated in the third magnetic field region MF3.

As already described, examples of the magnetic material constituting the magnetic core 11 include a metamagnetic material, a Permin bar characteristic material, and a synthetic antiferromagnetic material. Which magnetic material is used may be appropriately selected according to various characteristics (mainly the value of the first magnetic field strength H1) required for the current limiter 10.

The metamagnetic material refers to a material that undergoes a primary phase transition from a paramagnetic (PM) or anti-ferromagnetic (AFM) to ferromagnetic (FM) by a magnetic field. First-order phase transition by a magnetic field refers to having a point at which the change in magnetization related to the magnetic field becomes discontinuous. The magnetic field in which the first-order phase transition occurs in the metamagnetic material is normally a relatively large magnetic field of 1 to 10 T. Therefore, the current limiter 10 using this as the material of the magnetic core 11 includes a power system, a large-capacity capacitor circuit, and a power Applications for large currents such as transformer circuits are suitable. Note that some antiferromagnetic materials also have the characteristic that the magnetic flux density B increases rapidly if the magnetic field H is significantly increased. However, the magnetic field strength (that is, the first magnetic field strength H1) that causes such a change is obtained. It is extremely strong as 10 to 100 T, and it is practically impossible to generate such a magnetic field by the coil 12 of the current limiter 10. For this reason, even if an antiferromagnetic material is used as the material of the magnetic core 11, it is practically difficult to function as a current limiting device.

Metamagnetic materials are paramagnetic ferromagnetic transition type (PM-FM transition type) that transitions from paramagnetism to ferromagnetism by a magnetic field, and antiferromagnetic ferromagnetic transition type (AFM-FM) that transitions from antiferromagnetism to ferromagnetism. Classification). In the PM-FM transition type, the primary phase transition occurs only in the vicinity of the Curie temperature, so the operating temperature of the current limiter 10 is also limited to the vicinity of the Curie temperature. On the other hand, in the AFM-FM transition type, the primary phase transition occurs when the temperature is equal to or lower than the Neel temperature at which the antiferromagnetic state disappears. Therefore, the current limiter 10 can be operated at a wider temperature.

Specific examples of the metamagnetic material include La (FeSi) ₁₃ system, La (FeSi) ₁₃ H system, MnAs system, Mn (AsSb) system, MnAl system, FeRh system, NiMnIn system, Mn ₃ GaC system, Mn ₃ SnC. And Mn ₃ SnB-based materials. In particular, La (FeSi) ₁₃ H-based, MnAs-based, Mn (AsSb) -based, and MnAl-based materials that cause a first-order phase transition near room temperature are preferable, and most preferable is an MFM-based material that is an AFM-FM transition type metamagnetic material. Material. When using a material that does not cause a primary phase transition in the vicinity of room temperature, a heater or a cooling device may be used to maintain the temperature range in which the primary phase transition occurs.

Next, the permin bar characteristic material is a material that exhibits special BH characteristics, which is confirmed by Ni45 wt% Co 25 wt% Fe residue called a permin bar. Specifically, permin bar, Mo permin bar, super permin bar, iso palm, sen palm and the like can be mentioned. In addition, NiZn ferrite and CoB-based amorphous materials can also be mentioned as permin bar characteristic materials.

The permin bar characteristic material has no hysteresis at a relatively low magnetic field and shows a linear BH characteristic with a small inclination, and shows a BH characteristic with a large inclination when exceeding a certain magnetic field (first magnetic field strength H1). When the permin bar characteristic material is used, the first magnetic field strength H1 is 1/100 to 1/1000 that of the metamagnetic material. Therefore, if this material is used as the material of the magnetic core 11, a current limiter for low power is formed. It becomes possible to do.

In addition, if the temperature of the permbar characteristic material is below the Curie temperature at which ferromagnetism is maintained, the permeability changes in accordance with the magnetic field strength, so that it can operate in a wide range of temperatures including room temperature. Furthermore, since the permbar characteristic material has a small magnetostriction due to application of a magnetic field, it is possible to obtain high durability when used as the magnetic core 11. In addition, since the composition constituting the perminbar characteristic material is mostly a transition metal, there is also an advantage that the material cost is low compared to a metamagnetic material containing a platinum group element or a rare earth element.

In addition, since the magnetic permeability in the normal operation (that is, the first magnetic field region MF1) is 10 to 100 times greater than that of the metamagnetic material, the permember characteristic material has a perminver characteristic as the material of the magnetic core 11. The current limiting device 10 using a material can be used as a reactor during normal operation.

Next, a synthetic antiferromagnetic material refers to a material that exhibits antiferromagnetic properties by antiferromagnetic coupling between a ferromagnetic phase and a ferromagnetic phase. Unlike an antiferromagnetic material, a synthetic antiferromagnetic material has a low antiferromagnetic coupling strength. Therefore, when a certain magnetic field (first magnetic field strength H1) is exceeded, a ferromagnetic magnetization arrangement is obtained. A specific material includes a FeCo / Ru / FeCo thin film. When the synthetic antiferromagnetic material is used, the first magnetic field strength H1 is 1/10 to 1/100 that of the metamagnetic material. Therefore, if this is used as the material of the magnetic core 11, the current limiter for medium power is used. Can be configured.

As described above, the current limiter 10 according to the present embodiment is obtained by winding the coil 12 around the magnetic core 11 made of the magnetic material having the above-described characteristics, and has a very simple configuration. As a result, the current limiting operation can be performed spontaneously and at high speed without using an active element such as a diode and a thyristor, or a direct current power source, so that it is possible to realize cost reduction and improved reliability. Become.

FIG. 13 is a schematic diagram for explaining the configuration of the electromagnetic actuator 60 according to the second embodiment of the present invention.

13 includes a movable magnetic core 61, a fixed magnetic core 62, and a coil 63 wound around the movable magnetic core 61. The electromagnetic actuator 60 shown in FIG. The fixed magnetic core 62 is made of a ferromagnetic material such as iron, and the movable magnetic core 61 is made of a magnetic material having the characteristics shown in FIGS. Accordingly, as described with reference to FIG. 7, when the current I flowing through the coil 63 is equal to or less than the first current value I1, the movable magnetic core 61 behaves substantially as a nonmagnetic material. The state where 61 and the fixed magnetic core 62 are separated is maintained. When the current I flowing through the coil 63 exceeds the first current value I1, an attractive force is generated between the movable magnetic core 61 and the fixed magnetic core 62 due to a rapid increase in magnetization, and the two are brought into close contact with each other.

As described above, the electromagnetic actuator 60 according to the present embodiment uses the magnetic material having the characteristics shown in FIGS. 5 and 6 as the material of the movable magnetic core 61. Therefore, the circuit that interrupts the current path when a large current is generated. It is preferable to apply to a circuit breaker. In this case, since the response current for performing the interruption operation is determined by the material characteristics of the movable magnetic core 61, a high response speed can be realized, and reliability is not deteriorated due to aging of the spring.

In the example shown in FIG. 13, the magnetic material having the characteristics shown in FIGS. 5 and 6 is used for the movable magnetic core 61. Instead, the magnetic material having the characteristics shown in FIGS. A material may be used for the fixed magnetic core 62. In this case, a ferromagnetic material such as iron may be used as the material of the movable magnetic core 61. Furthermore, a magnetic material having the characteristics shown in FIGS. 5 and 6 may be used for both the movable magnetic core 61 and the fixed magnetic core 62, and the coil 63 may be wound around both.

FIG. 14 is a schematic diagram for explaining the configuration of a motor 70 according to the third embodiment of the present invention.

14 is provided with a stator 71 and a rotor 74. A plurality of stator magnetic poles 72 that are part of the stator 71 are periodically arranged on the inner peripheral wall of the stator 71, and a coil 73 is wound around each stator magnetic pole 72. Further, the same number of permanent magnets 75 as the stator magnetic poles 72 are arranged on the outer peripheral wall of the rotor 74 so as to face the stator magnetic poles 72.

In this embodiment, a magnetic material having the characteristics shown in FIGS. 5 and 6 is used as the material of the stator magnetic pole 72. Not only the stator magnetic pole 72 but the entire stator 71 may be made of the magnetic material. Accordingly, as described with reference to FIG. 7, when the current I flowing through the coil 73 is equal to or less than the first current value I1, the stator magnetic pole 72 behaves substantially as a nonmagnetic material. Hardly occurs. When the current I flowing through the coil 73 exceeds the first current value I1, the stator magnetic pole 72 behaves softly, so that the rotor 74 can be rotated. Thus, since the motor 70 according to the embodiment has a reduced cogging torque, the torque with respect to the current is increased, and high rotational efficiency can be obtained.

In the example shown in FIG. 14, the magnetic material having the characteristics shown in FIGS. 5 and 6 is used for the stator 71 side (stator magnetic pole 72). Alternatively, the magnetic material may be used for the rotor 74 side. I do not care. Furthermore, although a rotary motor is illustrated in FIG. 14, it can also be applied to a linear motor.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

For example, the current limiter 10 according to the first embodiment has a configuration in which the coil 12 is wound around the toroidal magnetic core 11, but the current limiter according to the present invention is not limited thereto. Therefore, the shape of the magnetic core may be an E shape, U shape, or I shape other than the toroidal shape. The magnetic core 11 may be provided with a magnetic gap. The coil 12 is not limited to the coated conductor using copper (Cu) as a core material, and a superconductor may be used.

10 current limiter 11 magnetic core 12 coil 20 AC power supply 30 load 40 breaker 50 capacitor 60 electromagnetic actuator 61 movable magnetic core 62 fixed magnetic core 63 coil 70 motor 71 stator 72 stator magnetic pole 73 coil 74 rotor 75 permanent magnet

Claims

In the first quadrant of the graph in which the magnetic characteristics are the first axis as the magnetic field and the second axis as the magnetic flux density or magnetization, the differential value of the magnetic flux density or magnetization with respect to the magnetic field in the first magnetic field region below the first magnetic field strength. Is the first value, and in the second magnetic field region that is stronger than the first magnetic field strength, the magnetic flux density with respect to the magnetic field or the differential value of the magnetization is a second value that is larger than the first value. Characteristic magnetic core.
In the third magnetic field region where the magnetic characteristic is stronger than the second magnetic field strength, the magnetic flux density or the differential value of the magnetization with respect to the magnetic field is a third value smaller than the second value. The magnetic core according to claim 1.
3. The magnetic core according to claim 1, wherein the characteristic curve indicating the magnetic characteristic substantially passes through an origin of the graph.
The magnetic core according to claim 1, comprising a metamagnetic material.
5. The magnetic core according to claim 4, wherein the metamagnetic material is an antiferromagnetic ferromagnetic transition material that transitions from antiferromagnetic to ferromagnetic by magnetic field strength.
The magnetic core according to any one of claims 1 to 3, wherein the magnetic core contains a permember characteristic material.
The magnetic core according to claim 1, comprising a synthetic antiferromagnetic material.
A reactor comprising the magnetic core according to any one of claims 1 to 7 and a coil wound around the magnetic core.
A current limiting device comprising the reactor according to claim 8.
A fixed magnetic core, a movable magnetic core, and a coil wound around at least one of the fixed magnetic core and the movable magnetic core, wherein the at least one of the fixed magnetic core and the movable magnetic core is any one of claims 1 to 7. An electromagnetic actuator comprising the magnetic core according to the item.
A motor comprising a rotor and a stator, wherein at least one of the rotor and the stator includes a magnetic core according to any one of claims 1 to 7.