JP2023043933A - Iron core structure and transformer - Google Patents

Abstract

To make magnetic resistance of a magnetic path in an iron core of a transformer uniform to alleviate concentration of a magnetic flux at inner corners of the iron core.SOLUTION: A gap member 6 made of a magnetoresistive material is arranged between a plurality of ferrite cores 20 on the yoke portion 22 side of an iron core 2 made up of the plurality of ferrite cores 20 such that magnetic flux density in an inner layer of the iron core 2 becomes uniform. A gap member 6 is disposed, for example, between ferrite cores 20 on the yoke portion 22 side at a corner portion 23 which is a joint portion between a leg portion 21 and a yoke portion 22 of the iron core 2.SELECTED DRAWING: Figure 1

Description

The present invention relates to an iron core for a high-frequency, large-capacity transformer, and more particularly to an iron core structure made of a ferrite core.

Iron cores of large-capacity transformers generally have a structure in which plate-shaped magnetic bodies made of, for example, ferrite cores are arranged in a picture frame and laminated in one direction (Patent Documents 1 and 2).

Japanese Utility Model No. 58-12915 JP-A-5-326289

In the transformers in which the same ferrite cores are stacked to configure the iron core, such as those disclosed in Patent Documents 1 and 2, the magnetic resistance of the outer magnetic path of the iron core increases due to the gap formed by the adhesive or the like between the ferrite cores. For this reason, as shown in FIG. 3, the magnetic flux from the leg portion 21 of the iron core 2 is biased toward the inner layer of the yoke portion 22 where the magnetic resistance is smaller, and at the joint portion between the leg portion 21 and the yoke portion 22 The magnetic flux concentrates at the corners 23 of the iron core 2, leading to an increase in iron loss and overheating.

In view of the above circumstances, it is an object of the present invention to equalize the magnetic resistance of the magnetic path in the iron core of a transformer and reduce the concentration of magnetic flux at the inner corners of the iron core.

Therefore, in one aspect of the present invention, a gap member made of a magnetoresistive material is arranged between the ferrite cores on the yoke portion side of the iron core made up of a plurality of ferrite cores so that the magnetic flux density of the inner layer of the iron core becomes uniform. It is a core structure that

In one aspect of the present invention, in the iron core structure, the iron core is arranged between the ferrite cores on the yoke portion side at the joint portion between the leg portion of the iron core and the yoke portion.

In one aspect of the present invention, in the core structure, the plurality of ferrite cores have the same cross section perpendicular to the core axial direction.

In one aspect of the present invention, in the iron core structure, the plurality of ferrites are bonded with an adhesive, and the ratio of the spacing between the ferrite cores with the gap member interposed to the spacing between the ferrite cores with the adhesive is The magnetic flux density is set to be uniform.

One aspect of the present invention is a transformer having the above core structure.

According to the present invention described above, the magnetic resistance of the magnetic path in the iron core of the transformer is made uniform, and the concentration of the magnetic flux at the inner corners of the iron core is alleviated.

1 is a cross-sectional view of a core structure of a transformer that is one embodiment of the present invention; FIG. Magnetic flux density distribution in an iron core that is one embodiment of the present invention. Magnetic flux density distribution in the core of a conventional transformer.

Embodiments of the present invention will be described below with reference to the drawings.

A core 2, which is one aspect of the core structure of the present invention shown in FIG. 1, is applied to a core-type transformer 1, for example.

The iron core 2 has, for example, a leg portion 21 in which the primary winding 3 and the secondary winding 4 are respectively wound as windings, and a yoke portion 22 in which the primary winding 3 and the secondary winding 4 are not wound. .

The leg portion 21 and the yoke portion 22 are composed of a plurality of rectangular parallelepiped or long plate-shaped ferrite cores 20 . The plurality of ferrite cores 20 are formed with the same dimensions, and have the same cross section perpendicular to the core axial direction. A plurality of ferrite cores 20 are arranged in a frame shape as shown in FIG. Adjacent ferrite cores 20 are bonded by a bonding method using an adhesive 5 well known in the field of core manufacturing.

A gap member 6 made of a magnetoresistive material is arranged between the ferrite cores 20 on the yoke portion 22 side of the iron core 2 so that the magnetic flux density of the inner layer of the iron core 2 becomes uniform. The gap member 6 illustrated in FIG. 1 is arranged perpendicular to the inner surface of the yoke portion 22 between the ferrite cores 20 on the yoke portion 22 side at the corner portion 23 which is the joint portion between the yoke portion 22 and the iron core leg portion 21 . be done.

As the magnetoresistive material, well-known heat-resistant fiber materials and adhesives such as meta-aramid fibers and epoxy resin adhesives are applied. The ratio between the gap G1 between the ferrite cores 20 interposed by the gap member 6 and the gap G2 between the ferrite cores 20 interposed by the adhesive 5 is set so that the magnetic flux density is uniform. In particular, it is more preferable to ensure that the interval G1 between the ferrite cores 20 is greater than the interval G2 between the ferrite cores 20. FIG.

If the plurality of ferrite cores 20 have similar shapes other than the depth, the effect of the spacing of the ferrite cores 20 on the magnetic path length is approximately the same, so the effect of relieving magnetic resistance is also the same. The vertical, horizontal, and depth dimensions of the cross section of the ferrite core 20 are determined based on the desired transmission power amount, voltage, current, or inductance value.

According to the above aspect of the iron core 2, the difference in magnetic resistance between the outer magnetic path and the inner magnetic path of the yoke portion 22 is reduced, the magnetic resistance of the magnetic path is made uniform, and the magnetic flux is concentrated at the inner corner of the iron core. is alleviated.

The effects of the iron core 2 of this embodiment will be described with reference to FIGS.

FIG. 2 shows the magnetic flux density distribution in the iron core 2 of this embodiment. The dimensions of the ferrite core 20 of the iron core 2 are long side L1=150 mm, short side L2=87.5 mm, and core axial depth D1=12 mm. The interval G1 between the ferrite cores 20 is 1 mm. The interval G2 between the ferrite cores 20 is 0.25 mm. The core axial depth D1 of the laminate of ferrite cores 20 is 360 mm. Conditions such as the number of turns and the current of the primary winding 3 and the secondary winding 4 of the iron core 2 in FIG. 2 are the same as those of the transformer 1 in FIG.

As shown in the magnetic flux density distribution shown in FIG. uniformity of magnetoresistance was observed. In addition, it was shown that the magnetic flux passes through the magnetic path of the outer layer of the yoke portion 22 due to the uniform magnetic resistance, and the concentration of the magnetic flux in the inner layer of the corner portion 23 of the iron core 2 can be alleviated. Therefore, even in the case of the iron core 2 in which the ferrite cores 20 of the same size of the present embodiment are laminated, the concentration of the magnetic flux at the corners 23 is suppressed. In particular, it is effective when two or more ferrite cores 20 are arranged in the height direction in the yoke portion 22 of the iron core 2 .

On the other hand, as a comparative example, in a mode in which the gap member 6 is arranged in the direction perpendicular to the inner surface of the iron core 2 on the side of the leg portion 21 at the corner portion 23 of the iron core 2, the magnetic flux density distribution of the iron core 2 is shown in FIG. It was confirmed that the magnetic flux concentration in the layers inside the corners 23 of the iron core 2 could not be suppressed.

By the way, in order to make the magnetic resistance of the magnetic path of the iron core 2 uniform, the number of ferrite cores 20 is reduced in the outer layers of the iron core 2, and the number of connecting portions of the ferrite cores 20 is increased in the inner layers of the iron core 2. Alternatively, the iron core 2 may employ ferrite cores having different dimensions.

On the other hand, in the iron core 2 of the present embodiment, since the iron core 2 is formed using the ferrite cores 20 having the same dimensions, the iron core 2 has a higher The magnetic resistance of the magnetic path of the iron core 2 can be made uniform at low cost.

Although the core structure of the above embodiment is applied to a core-type transformer, the core structure of the present invention can be applied to a shell-type transformer as well. It is clear that the effect is obtained. Further, although the core 2 has a two-layer structure, it is clear that the same effect as the above embodiment can be obtained even if the core structure of the present invention is applied to a core having three or more layers.

DESCRIPTION OF SYMBOLS 1... Transformer 2... Iron core 20... Ferrite core 21... Leg part 22... Yoke part 23... Corner part 3... Primary winding 4... Secondary winding 5... Adhesive 6... Gap member

Claims (5)

An iron core structure characterized by disposing a gap member made of a magnetoresistive material between ferrite cores on the yoke side of an iron core made up of a plurality of ferrite cores so that magnetic flux density in layers inside the iron core is uniform. 2. The iron core structure according to claim 1, wherein the gap member is arranged between the ferrite cores on the yoke side at the joints between the leg portions and the yoke portions of the iron core. 3. The iron core structure according to claim 1, wherein said plurality of ferrite cores have the same cross section orthogonal to the core axial direction. The plurality of ferrites are bonded with an adhesive,
4. The magnetic flux density of any one of claims 1 to 3, wherein a ratio of the spacing between the ferrite cores interposed by the gap member and the spacing between the ferrite cores interposed by the adhesive is set so that the magnetic flux density is uniform. or the core structure according to 1. A transformer having the core structure according to any one of claims 1 to 4.

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