JPS60154605A - Laminated magnetic iron core - Google Patents

Abstract

PURPOSE:To improve magnetic characteristics such as iron loss and noise and minimize increase of manufacturing cost by using a material having less magnetic loss for a particular steel plate. CONSTITUTION:An iron core of a 3-phase 3-leg inner iron type transformer is formed by abutting the leg irons 1a, 1b and yokes 2a, 2b, 2c, 2d as shown by A and B and then alternately laminating A and B. In both A and B, a low iron loss material is used for steel plates 2b, 2c having small area being abutted with the center leg and the center leg 1b among the upper and lower yokes. Since the length l2 where the center leg 1b and yoke 2b are in contact is shorter than the length l1 where the center leg 1b and the yoke 2a are in contact by the size of overlapping portion, the magnetic flux is more concentrated to 2b than 2a and the iron loss is also increased in such area. A low iron loss iron core can be realized using steel plates 2b, 1b, 2c of the low iron loss material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a laminated magnetic core used in electric induction equipment such as a transformer, and particularly to the structure of a steel plate constituting the core.

[Background of the invention]

For example, the iron core of the Sanwa three-legged internal iron transformer, which is one of the electric induction devices, is made of one leg iron la, lb and yoke 2a, 2b, 2c, 2d (A) and CB), and the steel plates butted in this way are (A), (
B) Constructed by alternating layers. In this core construction method, an overlapping portion is created at the yoke-side end of the center leg and the yoke-side end of the side leg. The magnetic flux density in the steel plate near this overlap is considerably higher than in other parts, increasing the iron loss of the core more than the iron loss of the material. In particular, it is known that iron loss density is high near the central leg and its overlap with the yoke.

As an improvement to the conventional core configuration, the entire core, as shown in Figure 1, is made of a material that suppresses iron loss caused by mechanically or thermally straining a normal silicon steel plate. (Hereinafter, this type of material will be referred to as a low core loss material), but this improvement has the disadvantage of increasing manufacturing costs.

In addition, as another improvement proposal, it has been proposed to reduce the loss by applying the same strain as mentioned above only to the parts of the core where iron loss is most likely to occur.
This method not only requires equipment for applying distortion, but also has the disadvantage of increasing the number of manufacturing steps.

[Purpose of the invention]

An object of the present invention is to provide an economical laminated magnetic core that minimizes increases in manufacturing costs while improving magnetic properties such as iron loss and noise.

[Summary of the invention]

The gist of the present invention is that the laminated magnetic core includes a central leg whose side legs and at least one end form a scalene triangle, and a yoke in which at least one of the upper and lower yokes in contact with the central leg is divided. In a magnetic core that is butt-jointed, among the steel plates of the center leg and the multiple steel plates that make up the yoke, the steel plate with a smaller area to be butted and the copper plate of the center leg have lower magnetic loss than the other steel plates. This is due to the material used.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described using FIG. 2. FIGS. 2(A) and 2(B) show the shape of the steel plates and the butt positions in each plane to be lap-jointed.

Note that among the steel plates, the white steel plates represent normal silicon steel plates, and the hatched steel plates represent low iron loss materials.

In both (A) and (B), among the upper and lower yokes, the steel plates 2b, 2c and the center leg 1b have a smaller area butted with the center leg.
uses low iron loss materials. The reason why iron loss can be reduced by such an iron core construction method is as follows. That is, as described above, magnetic flux concentrates at the yoke side end of the center leg, significantly increasing iron loss in the vicinity. However, even at the yoke side end of the same central leg, the degree of magnetic flux concentration differs depending on the joint shape and overlapping of the steel plates. First, consider the arrangement of the steel plates in (A).

In this case, in plan view, the length Q2 of the contact between the central leg 1b and the yoke 2b is shorter than the length Ql of the contact between the central leg ib and the yoke 2a by the overlap dimension, so the steel plate 2b is smaller than the steel plate 2a. Magnetic flux is concentrated.

Iron loss also increases. Therefore, if the steel plates 2b, lb, and 2c, which have a high core loss density, are made of low core loss materials, a low core loss core can be efficiently realized by adding a small amount of low core loss materials. (
The same applies to the steel plate arrangement in B).

Figure 3 (i) shows the central leg 1b of the Sanwa tripod inner iron type transformer core.
It is an enlarged view of the overlapping part of the yoke 2b and the yoke 2b.

3 is usually called a notch and is a void, and a steel plate is placed in the next layer. (11) is an actual measurement value showing the magnetic flux density at a position along the line from point C to d in (1). The leg irons were excited to 1.7 T. A part of the central leg 1b has a considerably high magnetic flux density, and the magnetic flux density at the yoke 2b is higher than other parts (about 1.7 T). Figure 41 (1) also shows the center leg 1b and the yoke 2b.
The difference from FIG. 3 (1) is that the butt position is shifted by the overlap dimension.

In this case as well, it can be seen that the magnetic flux is higher in the steel plate 2b than in other parts. The reason why such results are obtained is that due to the presence of the notch, areas with low magnetic flux density occur in the shaded areas in Figures 3 and 4 (1), and the magnetic flux is not shaded by that much. Because the magnetic flux flows into that part, it is interpreted that the magnetic flux density in that part is higher than when there is no notch. In a three-phase transformer, the magnetic flux flowing through each part changes from moment to moment, and Figures 5 to 7 show each time (U).

(2) This diagram schematically shows how the notch affects the flow of magnetic flux when the magnetic flux of the W leg is at its maximum.

Note that the iron cores in these figures are (A) and (
The iron core is constructed by alternately laminating steel plates arranged as shown in I3). Also, only the characteristic magnetic flux lines near the central leg were shown. Figures 5 to 7 show 0 legs 4. V-legs 5. This shows the instant at which the magnetic flux flowing through the W leg 6 reaches its maximum. At these moments, it is thought that a large amount of iron loss occurs in the steel plate marked with a circle in the figure due to the bias of the magnetic flux due to the gap at the butt portion and the presence of +JJ defects. Therefore, if the reduced loss material is used in the shaded area in FIG. 2, the introduced low a loss material can be efficiently used to reduce iron loss.

Experiments have shown that the iron loss in areas with intense magnetic flux concentration is approximately three times that in areas with no magnetic flux concentration. Using low iron loss materials in such parts has a great effect of reducing iron loss, but taking this into consideration, we calculated the iron loss of the core shown in Figure 2.
When a low core loss material is used as shown in FIG. 2, the average core loss is reduced by 2 to 3% compared to the case where the same amount of low core loss material is randomly used.

In this way, the present invention makes it possible to easily reduce iron loss while minimizing the use of low iron loss materials by appropriately arranging low iron loss materials, which are expensive to manufacture, and ordinary steel plates. be understood.

FIG. 8 shows another embodiment of the invention. The shape of the steel plate is the second
It is the same as the figure, but of the two steel plates that make up the yoke,
The arrangement of the steel plate of the yoke facing the short side of the central leg is reversed from that in Figure 2. In this case as well, if a low core loss material is used for the steel plate indicated by diagonal lines in the figure, the same effect of reducing core loss as in the core shown in FIG. 2 can be obtained.

FIG. 9 shows yet another embodiment of the present invention. This core has a structure in which the central leg separates the yoke. In order to overlap and join the copper plates shown in the same figure, the angle Q1 in
is chosen to be smaller than angle 02. Although this iron core (cut) does not generate any magnetic flux, there is a magnetic flux similar to that generated in the iron core in Figure 2. . 2)'C1 If these 53 plates are made to have a low ridge loss, a relatively small amount of low core loss material can be used to achieve the same effect of reducing core loss as in the core shown in FIG. 2.

〔Effect of the invention〕

According to the present invention, it is possible to minimize the increase in +M production costs while improving magnetic properties such as iron loss and noise.

[Brief explanation of drawings]

The first circle is a magnetic flux density distribution diagram at the structural joint of the core of a conventional Sanwa three-legged iron-type transformer, and Figures 5 to 71A are magnetic flux distribution diagrams due to notches in the core of a conventional three-phase two-sided transformer. 8 and 9 are plan views of other embodiments of the present invention. 1a...side leg, 1b...center leg, 2a, 2b...
] Two-part yoke, 2c, 2d...lower yoke, 3...notch. Rod 10 (A) (8) 1w ZC Kaya 2 figure (,'1) CB) Kaya 3 (2) (i) It) [B) 2eL (B) 4th (2) (i) (1; 2nd 50 (B) A certain otsu map (B) , v70 (A) CBnmaya 8 map (A) CB) lc 2aL

Claims (1)

[Claims] ], a side leg, a central leg whose at least one end has a scalene triangular shape, and a yoke in which at least one of upper and lower yokes in contact with the central leg is divided. In laminated magnetic cores that are butt-jointed. Among the plurality of steel plates constituting the copper plate of the center leg and the yoke, the steel plate whose area is smaller than that of the center leg and the steel plate of the center leg are made of a material with less magnetic loss than other steel plates. A laminated magnetic core.