JP6948170B2 - Core for current limiting reactor and current limiting reactor - Google Patents

Description

The present invention relates to a core for a current limiting reactor, a current limiting reactor, and a core for a current limiting reactor included in a current limiting reactor that limits the current flowing through a DC electric circuit.

A DC circuit breaker in which a contact provided with an electromagnetic trip device and a current limiting reactor are connected in series is known (see, for example, Patent Document 1).
The trip device opens a contact when the current flowing through the DC electric circuit exceeds a predetermined current value. When the contact opens, the current is cut off.
In this current limiting reactor, the main coil and the short-circuit coil are wound around a common core. The main coil is inserted in the DC electric circuit. In the short-circuit coil, the winding start and winding end are short-circuited. The main coil and the short-circuit coil are electromagnetically coupled. When a short-circuit accident occurs in the DC circuit, this current limiting reactor quickly increases the current in the DC circuit to the vicinity of the predetermined current value at which the contacts are opened by the trip device, and when the current value is exceeded, the current increases. Suppress.

Further, a transformer, a motor, a generator, etc. have a core (iron core) and a coil. The core is formed of an electromagnetic steel plate, soft ferrite, iron powder or the like as a material.
When the core is placed in a changing magnetic field, an eddy current is generated in the core so as to prevent the change in magnetic flux, and it is consumed as heat, resulting in loss (iron loss). In applications such as transformers, motors, and generators, it is desirable to suppress eddy currents in order to prevent heat generation. Therefore, for example, a dust core obtained by compressing and molding a ferromagnetic powder having an insulating film on the surface is used as a core material (see, for example, Non-Patent Document 1). The insulating coating formed on the surface of the particles can suppress eddy currents between the particles.

Japanese Unexamined Patent Publication No. 2016-181686

Hiroyuki Mitani, "Expectations for Next Generation Magnetic Material" Magnetic Iron Powder "", Kobe Steel Technical Report, 2015, Vol. 65, No. 2, pp. 12-15.

In the current limiting reactor described in Patent Document 1, when a large voltage is suddenly applied and the magnetic field generated by the main coil increases, as in the case of a short-circuit accident in a DC electric circuit, an eddy current is generated in the short-circuit coil. Due to the magnetic field generated by this eddy current, the current of the main coil (current of the DC electric circuit) rapidly increases to the vicinity of a predetermined current value, and when the current value is exceeded, the increase of the current is suppressed.
However, if a short-circuit coil is externally attached to the core of the current limiting reactor, the shape of the current limiting reactor is limited and the manufacturing cost thereof increases.
Further, unlike the cores used in applications such as transformers, motors, and generators, it is desirable that the cores included in the current limiting reactor generate more eddy currents.

An object of the present invention is to provide a method for manufacturing a core for a current limiting reactor, a current limiting reactor, and a core for a current limiting reactor that can generate a large amount of eddy currents.

In order to achieve the above object, the core for limiting current reactor of the present invention is
A core for limiting current reactor made of magnetic material,
A plurality of embedded members formed of a material having an electrical resistivity lower than that of the magnetic material and having through holes penetrating from the first main surface to the second main surface facing the first main surface. It is embedded embedding member of,
A first direction that coincides with the direction of the through hole of the embedded member, a second direction that is perpendicular to the first direction, and a third direction that is perpendicular to the first and second directions. In the above, a plurality of the embedded members are embedded at intervals from each other .
It is characterized by that.

Preferably, the core for the current limiting reactor of the present invention is
The magnetic material is iron-based and
The embedded member is made of gold, silver, copper, or aluminum.
It is characterized by that.

Further, the current limiting reactor of the present invention is
With the core for the current limiting reactor mentioned above,
The coil wound around the core for the current limiting reactor and
With
The magnetic field generated when an electric current flows through the coil interlinks with the first main surface and the second main surface of the embedded member.
It is characterized by that.

According to the present invention, a large amount of eddy current can be generated in the core for the current limiting reactor.

It is a perspective view which shows an example of the current limiting reactor which concerns on embodiment of this invention. FIG. 5 is a cross-sectional view taken along the line AA of the core of FIG. It is a vertical sectional view of the core of FIG. It is a figure which shows an example of the eddy current generated in the embedded member and the magnetic flux generated by it. FIG. 4A shows an example of an annular embedded member. FIG. 4B shows an example of a rectangular embedded member. It is a figure which shows an example of the manufacturing method of a core.

Hereinafter, a method for manufacturing a current limiting reactor core, a current limiting reactor, and a core for limiting current reactor according to the embodiment of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, the common components are designated by the same reference numerals, and the repeated description will be omitted.

FIG. 1 shows an example of the structure of the current limiting reactor 1 according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA of FIG. FIG. 3 is a vertical cross-sectional view of the core of FIG. 2 and 3 show an example of the internal structure of the core.
The current limiting reactor 1 has a core 10 and a coil 20.
The coil 20 is wound around the core 10. One end and the other end of the coil 20 are connected to the terminal T1 and the terminal T2, respectively. The coil 20 is inserted into a DC electric circuit, and a current i flows from the terminal T1 to the terminal T2, for example.

The core 10 is made of a magnetic material. The core 10 has a yoke Y1, a yoke Y2, a leg portion P1, and a leg portion P2. York Y1 and York Y2 face each other. The leg P1 connects the left end of the yoke Y1 and the left end of the yoke Y2. The leg P2 connects the right end of the yoke Y1 and the right end of the yoke Y2.
The coil 20 is wound around a part thereof, for example, the leg P1.

As shown in FIGS. 2 and 3, the core 10 has a large number of small embedded members 30 embedded therein.
As shown in FIG. 4, the embedded member 30 is, for example, an annular or rectangular member. The embedded member 30 has a first main surface 31 and a second main surface 32 facing the first main surface 31 and has a predetermined thickness. The embedded member 30 has a through hole 33 penetrating from the first main surface 31 to the second main surface 32. The embedding member 30 is made of a material having a low electrical resistivity such as gold, silver, copper, or aluminum. The embedding member 30 may be, for example, a ring made of metal wire such as gold, silver, copper, or aluminum.

The embedded member 30 functions as a short-circuit coil. As shown in FIGS. 1 and 3, when the current i flows through the coil 20, a magnetic flux Φm is generated inside the core 10. As shown in FIG. 4, the magnetic field Φm interlinks with the first main surface 31 and the second main surface 32 of each embedded member 30. At this time, it is desirable that the magnetic field Φm is interlinked with the first main surface 31 and / or the second main surface 32 of the embedded member 30 at an angle as close to vertical as possible.
When the current i of the coil 20 changes (that is, the magnetic flux Φm changes), an eddy current ie flows through the embedded member 30. Since the electric resistance of the embedded member 30 is smaller than that of the magnetic material forming the core 10, a large eddy current ie flows. Due to the eddy current ie, the magnetic flux Φe is generated in the direction of suppressing the change of the magnetic flux Φm. Therefore, the magnetic flux Φm is less likely to be saturated as compared with the case where the embedded member 30 is not provided.

The position where the embedding member 30 is embedded and its density are adjusted according to the degree of suppression of the magnetic flux Φm in the core 10. For example, as shown in FIG. 3, the embedding member 30 may be embedded in the yoke Y1, the yoke Y2, and the leg P2 other than the leg P1 around which the coil 20 is wound. Further, the embedding member 30 may be embedded only in the leg portion P2 facing the leg portion P1. The embedding member 30 may be embedded in all of the yoke Y1, the yoke Y2, the leg portion P1, and the leg portion P2.
Further, by making the outer shape of the embedded member 30 relatively small, the degree of freedom in the shape of the core 10 can be increased.

The core 10 is manufactured by embedding a large number of embedded members 11 in a powder containing magnetic particles such as iron powder, and compressing and molding the core 10.
The magnetic powder used for producing the core 10 may have an insulating film formed on the surface of the particles, but it is desirable that the magnetic powder has no insulating film formed on the surface of the particles. In the core 10 manufactured by using particles having no insulating film formed on the surface, eddy currents are also generated between the particles.

The powder material used in the production of the core 10 is preferably an iron-based magnetic material. For example, pure iron, iron-silicon alloy, iron-nitrogen alloy, iron-nickel alloy, iron-carbon alloy, iron-boron alloy, iron-cobalt alloy, iron-phosphorus alloy, iron-nickel The core 10 can be manufactured by using powders of a cobalt-based alloy, an iron-aluminum-silicon alloy (sendust alloy), an iron amorphous material, a fine crystal material, and the like.

FIG. 5 shows an example of a method for manufacturing the core 10.
When manufacturing the core 10, first, powder containing magnetic particles is put into a mold while embedding a plurality of embedded members 30 in the powder (S1). Here, it is desirable that the particles contained in the powder do not have an insulating film formed on the surface thereof. Next, the powder in which the embedding member 30 is embedded is compressed by a press and molded (S2).
After the core 10 was compressed and molded, the embedding member 30 was deformed so much that there is no problem as long as it is closed.
Further, in order to prevent the embedded member 30 from being deformed during compression / molding, the yoke Y1, the yoke Y2, the leg portion P1 and the leg portion P2 are separately manufactured as prisms by compression / molding, and then four pieces are manufactured. The prisms may be joined into a rectangle. In this case, by applying a force along the longitudinal direction of the prism during compression / molding, a force is applied perpendicularly to the first main surface 31 and the second main surface 32 of the embedding member 30, and the embedding member 30 is embedded. It is possible to prevent the inclusion member 30 from being deformed.

In the above-described embodiment, an example of the rectangular core 10 is shown, but the core 10 is not limited to this, and the core 10 may have another shape such as a rod shape or an annular shape. Further, in the above-described embodiment, an example of the annular or rectangular embedded member 30 is shown, but the present invention is not limited to this, and the embedded member 30 may have another shape as long as it has a shape that generates an eddy current. ..

According to the present invention, since a large number of short-circuit coils (embedded members) are arranged in the core for the current limiting reactor, a large amount of eddy current is generated. Further, in a core manufactured by using particles having no insulating film formed on the surface, eddy currents are also generated between the particles. Therefore, the current limiting reactor core according to the present invention does not need to attach an external short-circuit coil, but when a large voltage is suddenly applied as in the case of a short-circuit accident of a DC electric circuit, the current of the coil (current of the DC electric circuit). Can be rapidly increased to near a predetermined current value, and when the current value is exceeded, the increase in current can be suppressed.
Further, since a large number of short-circuit coils are arranged in parallel, the frequency characteristics of the current limiting reactor core are improved.

Although the embodiments of the present invention have been described above, various modifications and combinations required due to design or manufacturing convenience and other factors are described in the inventions and embodiments of the invention described in the claims. It is included in the scope of the invention corresponding to the specific example.

1 ... current limiting reactor, 10 ... core, 20 ... coil, 30 ... embedded member, 31 ... first main surface of embedded member, 32 ... second main surface of embedded member, 33 ... embedded member Through hole

Claims (3)

A core for limiting current reactor made of magnetic material,
A plurality of embedded members formed of a material having an electrical resistivity lower than that of the magnetic material and having through holes penetrating from the first main surface to the second main surface facing the first main surface. It is embedded embedding member of,
A first direction that coincides with the direction of the through hole of the embedded member, a second direction that is perpendicular to the first direction, and a third direction that is perpendicular to the first and second directions. In the above, a plurality of the embedded members are embedded at intervals from each other .
A core for a current limiting reactor that is characterized by this. The magnetic material is iron-based and
The embedded member is made of gold, silver, copper, or aluminum.
The core for a current limiting reactor according to claim 1. The core for limiting current reactor according to claim 1 or 2.
The coil wound around the core for the current limiting reactor and
With
The magnetic field generated when an electric current flows through the coil interlinks with the first main surface and the second main surface of the embedded member.
A current limiting reactor characterized by that.

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