JP2023043934A - Iron core structure and transformer - Google Patents

Abstract

An object of the present invention is to reduce magnetic flux concentration and core loss to the inner peripheral side of a joint between a winding winding portion and a non-winding winding portion of an iron core made of a ferrite core.
A transformer (1) includes a hollow prismatic iron core (2) composed of ferrite cores (21-25), and a primary winding (3) and a secondary winding (4) wound around the iron core (2). A corner portion 28 of the iron core 2, which is a junction portion between the winding portion 26 and the non-winding portion 27, is formed by arranging and unidirectionally stacking a plurality of ferrite cores 21 to 25 having different cross sections. The cross section becomes smaller from the outer peripheral side of the iron core 2 to the inner peripheral side.
[Selection drawing] Fig. 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 Publication No. 58-12915 JP-A-5-326289

In an iron core with laminated ferrite cores, the magnetic flux at the joints between the winding and non-winding windings of the iron core is generated inside the core due to the magnetic resistance caused by the gaps between the adjacent ferrite cores. It concentrates on the peripheral side, and iron loss also occurs intensively on the inner peripheral side.

In view of the above circumstances, an object of the present invention is to alleviate the magnetic flux concentration and core loss on the inner peripheral side of the joint between the winding winding portion and the non-winding winding portion of an iron core made of a ferrite core. and

Accordingly, one aspect of the present invention is an iron core structure in which the ferrite cores having different cross sections are disposed at the joints between the winding winding portion and the non-winding winding portion of the iron core made of a ferrite core.

In one aspect of the present invention, in the iron core structure, the cross section becomes smaller from the outer circumference side to the inner circumference side of the iron core.

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

According to the present invention described above, it is possible to reduce the concentration of magnetic flux to the inner peripheral side of the junction between the winding portion and the non-winding portion of an iron core made of a ferrite core and iron loss.

FIG. 2 is a cross-sectional view of the core structure in the transformer of Embodiment 1 of the present invention; Explanatory drawing of the magnetic resistance of the magnetic circuit imitating the outer layer, middle layer, and inner layer of the iron core of a transformer.

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

The core structure of Embodiment 1 shown in FIG. 1 is applied to a core-type transformer 1, for example.

A transformer 1 includes an iron core 2 composed of ferrite cores 21 to 25 and a primary winding 3 and a secondary winding 4 wound around the iron core 2 .

For example, as shown in the figure, the iron core 2 has rectangular parallelepiped or elongated plate-shaped ferrite cores 21 to 25 arranged in a picture frame and laminated in one direction to form a hollow prism.

A winding winding portion 26 corresponding to a leg portion of the core 2 around which the primary winding 3 and the secondary winding 4 are respectively wound, and a winding winding portion 26 corresponding to the leg portion of the core 2 around which the primary winding 3 and the secondary winding 4 are respectively wound. The non-wound winding portion 27 corresponding to the yoke portion is formed by arranging and unidirectionally stacking the ferrite cores 21 of the same size. Adjacent ferrite cores 21 are bonded by bonding techniques well known in the art of core manufacturing.

A plurality of ferrite cores 21 to 25 having different cross sections perpendicular to the axial direction of the core 2 are arranged and arranged at the corners 28 of the core 2, which are the joints between the winding windings 26 and the non-winding windings 27. It is laminated in one direction. The cross section becomes smaller from the outer peripheral side of the iron core 2 to the inner peripheral side. Adjacent ferrite cores 21 to 25 are also bonded by the well-known bonding method.

In the case of the three-layer core 2 illustrated in FIG. 1, the joint 29 has a substantially square cross-sectional shape. In the outer layer OUT (FIG. 2) of the joint portion 29, a ferrite core 21 having a rectangular cross section of normal size and a ferrite core 22 having a rectangular cross section of about 2/3 of the normal size are arranged. Furthermore, ferrite cores 23 and 24 having a cross section of approximately 1/3 or approximately 1/3 to 4/5 of the ferrite core 21 are arranged in the middle layer CEN (in the figure) on the inner peripheral side of the outer layer OUT. Ferrite cores 24 and 25 each having a cross section of approximately 1/3 or approximately 1/10 of the ferrite core 21 are arranged in the inner layer IN (in the figure) on the inner peripheral side of the intermediate layer CEN.

In particular, the ferrite cores 21 to 25 are arranged and laminated such that the magnetic resistances of the inner layer IN, the middle layer CEN and the outer layer OUT of the iron core 2 are approximately uniform. That is, the magnetoresistance Rm_IN of the inner layer IN, the magnetoresistance Rm_CEN of the middle layer CEN, and the magnetoresistance Rm_OUT of the outer layer OUT of the three-layer core 2 illustrated in FIG. l _IN : length of magnetic path of inner layer IN, l _CEN : length of magnetic path of middle layer CEN, l _OUT : length of magnetic path of outer layer OUT, S: magnetic path length of outer layer OUT, cross-sectional area of the path, μ ₀ : magnetic permeability of vacuum, l _gap : length of gap between adjacent ferrite cores 21 to 25 in inner layer IN, middle layer CEN, and outer layer OUT, S _gap : cross-sectional area of said gap).

Normal magnetoresistance Rm_OUT, magnetoresistance Rm_CEN and magnetoresistance Rm_IN are given by the following equation (4).

The magnetoresistance Rm_OUT, magnetoresistance Rm_CEN, and magnetoresistance Rm_IN are larger than the magnetoresistance of the ferrite cores 21-25 in the gaps between the adjacent ferrite cores 21-25. adjusted approximately evenly. In particular, since the magnetic resistivity μ(φ) is a function of the magnetic flux φ, the magnetic resistance Rm_OUT, the magnetic resistance Rm_CEN, and the magnetic resistance Rm_IN are calculated using numerical values such as the finite element method so that they are equivalent as shown in the following equation (5). Analytical techniques adjust the length and number of the gaps.

As described above, the corners 28 are ferrite cores having different cross-sectional dimensions so that, for example, the length of the gap between the adjacent ferrite cores 21 to 25 becomes smaller from the outer circumference to the inner circumference of the iron core 2. 21-25 are arranged and stacked. As a result, the number of gaps between the ferrite cores 21 to 25 is small on the outside of the iron core 2 and large on the inside. 26 and the non-winding winding portion 27) is relieved.

Although there are technical restrictions on increasing the size of the ferrite cores 21 to 25 of the iron core 2, it can be realized by arranging and laminating ferrite cores of available sizes. In particular, by making the magnetic resistance uniform by adjusting the number of gaps, it is possible to prevent the magnetic flux from concentrating on the inner peripheral side of the iron core 2 and iron loss from concentrating on the hard-to-cool inner side.

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. Moreover, although the core 2 is a three-layer core, 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 four or more layers.

DESCRIPTION OF SYMBOLS 1... Transformer 2... Iron core 21-25... Ferrite core 26... Winding winding part 27... Non-winding winding part 28... Corner part 3... Primary winding 4... Secondary winding

Claims (3)

1. A core structure comprising ferrite cores having different cross-sections arranged at joints between a winding portion and a non-winding portion of an iron core comprising a ferrite core. 2. The iron core structure according to claim 1, wherein said cross section becomes smaller from the outer peripheral side to the inner peripheral side of said iron core. A transformer having the core structure according to claim 1 or 2.

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