JP6781043B2 - Composite magnetic circuit inductor - Google Patents

Description

The present invention relates to inductors, especially composite magnetic circuit inductors.

The inductor is one of the basic elements in the circuit. A normal inductor is made by winding a coil, but in order to increase the amount of inductance and improve the quality factor of the coil, the coil is wound on the magnetic core, and the material of the magnetic core has an important influence on the performance of the inductor. Is exerting. Of the many materials, ferrite material is often used as the magnetic core material, and since ferrite material has high magnetic permeability, it is effective in creating a large inductance. However, since the ferrite material also has an undesired property that it is easily magnetically saturated, it has been considered as one of the solutions to use a larger size magnetic core in order to eliminate this drawback. This increases the cost of the inductor and hinders the mounting of the inductor on the circuit board. Another solution is to open an air gap in the ferrite material, but it is necessary to increase the gap size in order to prevent saturation of the magnetic core, but if the gap is manually provided, the gap size will vary. There was also a decrease in performance indicators such as inductor loss.

For example, in the technique shown in Patent Document 1, a ferrite material is used as all the materials of the magnetic core. In this case, although it is suitable for producing a large magnetic core, there is a problem that the shape becomes large.

Patent Document 1: Japanese Patent Application Laid-Open No. 2014-132602

The present invention provides a composite magnetic path inductor, and by introducing a selected magnetic core material, it solves a problem caused by simply using a ferrite material.

Means for Solving the Invention

The technical solution adopted by the present invention to solve the above technical problems is to make a composite magnetic circuit inductor including a magnetic core and a coil. The magnetic core has an annular first magnetic core and a rod-shaped second magnetic core located in the first magnetic core, and both end faces of the second magnetic core are inner side walls of the first magnetic core. A coil is wound around the second magnetic core so as to be connected to the connection surfaces at the corresponding positions of the above. In a composite magnetic circuit inductor in which a coil is wound around the second magnetic core, the magnetic permeability of the second magnetic core is larger than the magnetic permeability of the first magnetic core, and the magnetic permeability of the second magnetic core is and the 50H / m or more, the ratio of the width W of the first direction substantially parallel to said second magnetic core of the magnetic core, the length of the first direction perpendicular to the second magnetic core of the magnetic core L The L / W is 1.8 or more, the first magnetic core is a magnetic core made of metal soft magnetic powder, and the second magnetic core is a magnetic core made of either ferrite or metal soft magnetic powder.

In one embodiment of the present invention, the magnetic permeability of the first magnetic core is 40 to 100 H / m.

In one embodiment of the present invention, the connecting surface of the first magnetic core is flush with the inner wall surface of the first magnetic core.

In one embodiment of the present invention, the connecting surface of the first magnetic core protrudes from the inner wall surface of the first magnetic core.

In one embodiment of the present invention, the connecting surface of the first magnetic core is recessed inward from the inner wall surface of the first magnetic core.

In one embodiment of the present invention, there is a gap having a width of 0.5 mm or less between at least one end surface of the second magnetic core and the connecting surface of the first magnetic core.

In one embodiment of the invention, the second magnetic core comprises a gap.

In one embodiment of the invention, the gap is formed by an adhesive.

In one embodiment of the invention, the gap is formed of an insulating material.

In one embodiment of the present invention, the metal soft magnetic powder is either Fe powder, FeSiAl powder, FeSi mixed powder or iron-based amorphous powder.

In one embodiment of the invention, the coil is wound with copper wire, copper coated aluminum wire or aluminum wire.

The composite magnetic circuit inductor of the present invention includes a ferrite magnetic core and a metal soft magnetic powder magnetic core at the same time. Compared with the ferrite magnetic core, the magnetic core made of metal soft magnetic powder has many minute air gaps inside, so that the magnetic core is less likely to be saturated. As described above, the metal soft magnetic powder core does not need to have a large volume like the ferrite core, and the performance is not deteriorated by a gap that is too large. Therefore, the inductor of the present invention can be suppressed in size and cost, and its performance is guaranteed.

In order to clarify and clarify the above-mentioned object, feature and advantage of the present invention, a specific embodiment of the present invention will be described in detail below in relation to the drawings.
It is a structural schematic drawing of the composite magnetic circuit inductor in the 1st Example of this invention. The magnetic path of the composite magnetic path inductor in the Example shown in FIG. 1 is shown. It is a structural schematic drawing of the composite magnetic circuit inductor in the 2nd Example of this invention. It is a structural schematic drawing of the composite magnetic circuit inductor in the 3rd Example of this invention. It is a structural schematic drawing of the composite magnetic circuit inductor in the 4th Example of this invention. In the first embodiment, it is a graph which shows the value of the inductance when a DC bias current is passed. In the first embodiment, it is a graph which shows the value of the inductance when the DC bias current is passed when the ratio L / W is changed.

[Constitution]
FIG. 1 is a schematic structural diagram of a composite magnetic circuit inductor according to the first embodiment of the present invention. With reference to the place shown in FIG. 1, the inductor 10 in this embodiment has an “O” or “mouth” -shaped structure. The magnetic core of the inductor 10 has an annular first magnetic core 11 on the outside and a rod-shaped second magnetic core 12 inside the annular first magnetic core 11. The length of the second magnetic core 12 can be exactly the internal width of the first magnetic core 11. In this way, both end faces 12a of the second magnetic core 12 and the connecting surfaces 11a at the corresponding positions of the inner wall surface of the first magnetic core 11 are in contact with each other. In this embodiment, the connecting surface 11a of the first magnetic core 11 and the inner wall surface of the first magnetic core 11 are flush with each other. Further, the first magnetic core 11 is not a magnetic core in which the divided magnetic cores are combined, but is preferably an integrally molded magnetic core. By using the integrally molded magnetic core, a minute gap between the magnetic cores in the magnetic path is not formed, and the loss due to the leakage flux generated in the gap can be suppressed.

In the above, a ferrite magnetic core is used as the second magnetic core, but a metal soft magnetic powder having a magnetic permeability different from that of the first magnetic core can also be used for the second magnetic core. In that case, it is preferable to use a material having a higher magnetic permeability than the first magnetic core for the second magnetic core. For example, a magnetic core having a magnetic permeability of 40 to 100 H / m is used for the first magnetic core, and a magnetic core having a magnetic permeability of 50 H / m or more and a higher magnetic permeability than the first magnetic core is used for the second magnetic core. Can be done. In this case, a mixed powder or FeSiAl powder obtained by mixing two types of FeSi powder can be used for the first magnetic core, and FeSiAl powder can be used for the second magnetic core. For example, a magnetic core made of FeSi powder having a magnetic permeability of about 100 H / m may be used for the first magnetic core, and ferrite having a magnetic permeability of about 1600 H / m may be used for the second magnetic core. Further, an inductor is configured by using a magnetic core made of FeSi powder having a magnetic permeability of about 100 H / m for the first magnetic core and using a magnetic core made of FeSiAl powder having a magnetic permeability of about 150 H / m for the second magnetic core. May be good. The magnetic permeability of the first magnetic core is preferably 40 to 100 H / m, but it is considered that the same effect can be obtained by using a magnetic core having a magnetic permeability of up to 500 H / m. The magnetic permeability in the present invention indicates the initial magnetic permeability.

The second magnetic core 12 may be located exactly in the center of the first magnetic core 11 and may be somewhat off. A coil 13 is wound around the second magnetic core 12.

The second magnetic core 12 and the first magnetic core 11 can be connected by various fixing methods such as a small amount of adhesive. The adhesive can create gaps, which do not affect the performance of the inductor. Depending on the application, the gap can also be desirable.

In this embodiment, the width W of the inductor 11 in the direction parallel to the second magnetic core 12 (parallel direction in the drawing) and the direction perpendicular to the second magnetic core 12 provided with the first magnetic core 11 (FIG. If the length (in the vertical direction) is L, the L / W is preferably 1.2 or more.

In the examples of the present invention, the metal soft magnetic powder can be Fe powder, FeSiAl powder, FeSi mixed powder or iron-based amorphous powder. The first magnetic core 11 is formed of the metal soft magnetic powder by the pressing method.

FIG. 2 shows the magnetic path of the composite magnetic path inductor in the embodiment shown in FIG. Referring to what is shown in FIG. 2, the rod-shaped second magnetic core 12 provides a concentrated magnetic path as shown by the broken line in the figure to the coil 13 wound around the rod-shaped second magnetic core 12, and the annular first magnetic circuit. Two composite magnetic flux circuits are formed with the magnetic core 11 of the above to realize parallelism.

Compared with the ferrite magnetic core, the magnetic core made of metal soft magnetic powder has many minute air gaps inside, so that the magnetic core is less likely to be saturated. As described above, if the metal soft magnetic powder magnetic core is the first magnetic core 11 in the present embodiment, it is not necessary to have a large volume like the ferrite magnetic core, and the performance may be deteriorated due to an excessively large gap. Absent. Therefore, the inductor in this embodiment can be suppressed in size and cost, and its performance is guaranteed.

FIG. 3 is a schematic structural diagram of the composite magnetic circuit inductor according to the second embodiment of the present invention. Compared to the first embodiment, the inductor 20 in this embodiment also includes a first magnetic core 21, a second magnetic core 22, and a coil (not shown in the figure). The connecting surface 21a of the first magnetic core 21 protrudes from the inner wall surface of the first magnetic core. Further, since the length of the second magnetic core 22 is slightly shorter than the internal width of the first magnetic core 21, a gap 24 is formed between both end surfaces 22a of the second magnetic core 22 and the corresponding connecting surface 21a. It is formed. This gap can be formed with an adhesive or other insulating material. In one embodiment, the width of each gap is 0.5 mm or less. The gap may be formed of an air gap, a sheet-shaped insulating material, or the like.

The merit of introducing the gap is that the saturation of the second magnetic core 22 of the ferrite material can be prevented.

FIG. 4 is a schematic structural diagram of the composite magnetic circuit inductor according to the third embodiment of the present invention. Compared to the first embodiment, the inductor 30 in this embodiment also includes a first magnetic core 31, a second magnetic core 32, and a coil (not shown in the figure). The difference is that the connecting surface 31a of the first magnetic core 31 is recessed inward from the inner side wall of the first magnetic core. Further, since the length of the second magnetic core 32 is slightly shorter than the internal width of the first magnetic core 31, a gap 34 is formed between both end surfaces 32a of the second magnetic core 32 and the corresponding connecting surfaces 31a. It is formed. This gap can be formed with an adhesive or other insulating material. In one embodiment, the width of each gap is less than 0.5 mm. The gap may be formed of an air gap, a sheet-shaped insulating material, or the like.

In the second and third embodiments described above, the number of gaps is two, that is, there are gaps between both end faces of the second magnetic core and the corresponding connecting faces. However, it can also be understood that the gap only needs to be between one end face of the second magnetic core and the corresponding connecting surface. The width of the gap in this case may be less than 1 mm. The gap may be formed of an air gap, a sheet-shaped insulating material, or the like.

FIG. 5 is a schematic structural diagram of the composite magnetic circuit inductor according to the fourth embodiment of the present invention. Compared to the first embodiment, the inductor 40 in this embodiment also has a first magnetic core 41, a second magnetic core 42, and a coil not shown in the figure. The difference is that the second magnetic core 42 has two gaps 42a, 42b. This gap can be formed with an adhesive or other insulating material. However, the gap provided in the second magnetic core is not limited to two, and may be one or three or more. The gap may be formed of an air gap, a sheet-shaped insulating material, or the like.

FIG. 6 is a diagram showing DC superimposition characteristics obtained when a DC bias current is passed through the composite magnetic circuit inductor of the first embodiment. The frequency of the current was 20 kHz, and a voltage of 1 V was applied. As is clear from FIG. 6, as compared with the inductor composed only of ferrite, the magnetic core made of metal soft magnetic powder is used for the first magnetic core, and the magnetic permeability of the second magnetic core is higher than that of the first magnetic core. It is considered that an inductor using a high metal soft magnetic powder or ferrite can obtain high DC superimposition characteristics even when the current value is high, and can improve the DC superimposition characteristics in a high magnetic field. Further, it can be confirmed that the DC superimposition characteristic at a high current value is better when the magnetic core made of metal soft magnetic powder is used for the second magnetic core than when ferrite is used for the second magnetic core. It was.

FIG. 7 is a diagram showing DC superimposition characteristics obtained when a DC bias current is passed by changing the ratio L / W in the composite magnetic circuit inductor of the first embodiment. The frequency and voltage are the same as in FIG. As is clear from FIG. 7, in the inductor in which the metal soft magnetic powder is used for the first magnetic core and ferrite is used for the second magnetic core, the L / W is 1.2 rather than 1.0. However, it was confirmed that a high DC superimposition characteristic can be obtained at a high current value. Further, it was confirmed that when the L / W was set to 1.8, even higher DC superimposition characteristics could be obtained.

In each of the above embodiments of the present invention, the coil can be wound with copper wire, copper coated aluminum wire or aluminum wire. Among them, the aluminum wire is inexpensive, and even when used in the present invention, it still meets the performance requirements of the inductor. Therefore, if an aluminum wire is used, the cost can be further reduced.

[effect]
In the present invention, by using a magnetic core having a higher magnetic permeability than the first magnetic core for the second magnetic core, the magnetic flux can be easily concentrated inside the coil wound around the second magnetic core, and more direct current can be obtained. The superimposition characteristic can be improved. Further, by shortening the magnetic path length constituting the magnetic core of the inductor as much as possible, a larger DC superimposition characteristic can be obtained. Further, in an inductor using a magnetic core having a higher magnetic permeability than the first magnetic core for the second magnetic core, the width W is reduced by shortening the length of the second magnetic core having a high magnetic permeability, and the ratio L / It is considered that the DC superimposition characteristic can be improved by increasing W.

It is considered that the larger the gap size, the worse the characteristics due to the leakage flux. In order to eliminate the leakage flux as much as possible, it is preferable that the gap between the first magnetic core and the second magnetic core is also minimized. By doing so, the characteristics can be improved. When a gap is provided between the first magnetic core and the second magnetic core, it is preferable to make the dimensions as small as possible. However, if the gap size is too small, it may be difficult to assemble the magnetic core due to the manufacturing intersection of the magnetic core. Therefore, the gap size is preferably 0.5 mm or less.

The present invention has been described with reference to the above specific examples, but for ordinary engineers in the art, the above examples are merely for explaining the present invention. It should also be recognized that various equivalent modifications or substitutions can be made without departing from the spirit of the present invention. Therefore, any modification or modification made in the above embodiment within the scope of the substantial purpose of the present invention is included in the claims of the present application.

Other embodiments

The second magnetic core is not limited to one, and may be two or more. The second magnetic core is not limited to a shape such as a square or a rectangle in cross section, but may be a shape such as a polygon, a perfect circle, or an ellipse. By making the cross section of the second magnetic core a polygon or a circle, the coil can be wound more along the outer circumference of the magnetic core. The shape is not limited to a rod shape, and a circular or circular magnetic core having an opening at the center may be used.

The first magnetic core is not limited to one, and may be two or more. A plurality of annular magnetic cores may be laminated together. By doing so, it is not necessary to bother to produce a mold that matches the shape by laminating the magnetic cores so that they have a shape determined according to the specifications.

10, 20, 30, 40 ... Inductors,
11, 21, 31, 41 ... 1st magnetic core 12, 22, 32, 42 ... 2nd magnetic core 13 ... Coil

Claims (12)

Including magnetic core and coil
The magnetic core has an annular first magnetic core and a rod-shaped second magnetic core located in the first magnetic core.
Both end faces of the second magnetic core are connected to connecting surfaces at corresponding positions on the inner wall of the first magnetic core, respectively.
In a composite magnetic circuit inductor in which the coil is wound around the second magnetic core,
The magnetic permeability of the second magnetic core is larger than the magnetic permeability of the first magnetic core, and the magnetic permeability of the second magnetic core is 50 H / m or more.
Wherein the width W substantially parallel to the second magnetic core of the first magnetic core, the ratio L / W between the length of the first direction perpendicular to the second magnetic core of the magnetic core L 1.8 That's it,
A composite magnetic circuit inductor characterized in that the first magnetic core is a magnetic core made of a soft magnetic powder of metal, and the second magnetic core is a magnetic core made of ferrite. Including magnetic core and coil
The magnetic core has an annular first magnetic core and a rod-shaped second magnetic core located in the first magnetic core.
Both end faces of the second magnetic core are connected to connecting surfaces at corresponding positions on the inner wall of the first magnetic core, respectively.
In a composite magnetic circuit inductor in which the coil is wound around the second magnetic core,
The magnetic permeability of the second magnetic core is larger than the magnetic permeability of the first magnetic core, and the magnetic permeability of the second magnetic core is 50 H / m or more.
Wherein the width W substantially parallel to the second magnetic core of the first magnetic core, the ratio L / W between the length of the first direction perpendicular to the second magnetic core of the magnetic core L 1.8 That's it,
A composite magnetic circuit inductor in which the first magnetic core and the second magnetic core are magnetic cores made of a soft magnetic powder of metal. The composite magnetic circuit inductor according to claim 1 or 2, wherein the magnetic permeability of the first magnetic core is 40 to 100 H / m. The composite magnetic circuit inductor according to any one of claims 1 to 3, wherein the connecting surface of the first magnetic core is flush with the inner wall surface of the first magnetic core. The composite magnetic circuit inductor according to any one of claims 1 to 3, wherein the connecting surface of the first magnetic core projects from the inner wall surface of the first magnetic core. The composite magnetic circuit inductor according to any one of claims 1 to 3, wherein the connecting surface of the first magnetic core is recessed inward from the inner side wall of the first magnetic core. Any one of claims 1 to 6, wherein a gap having a width of 0.5 mm or less is provided between at least one end surface of the second magnetic core and the connecting surface of the first magnetic core. The composite magnetic circuit inductor according to the section. The composite magnetic circuit inductor according to any one of claims 1 to 6, wherein the second magnetic core has a gap. The composite magnetic circuit inductor according to claim 7 or 8, wherein the gap is formed by an adhesive. The composite magnetic circuit inductor according to claim 7 or 8, wherein the gap is formed of an insulating material. The composite magnetic circuit inductor according to any one of claims 1 to 10, wherein the metal soft magnetic powder is any one of Fe powder, FeSiAl powder, FeSi mixed powder, and iron-based amorphous powder. .. The composite magnetic circuit inductor according to any one of claims 1 to 11, wherein the coil is wound with a copper wire, a copper-coated aluminum wire, or an aluminum wire.

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