JPS62250612A - Foil-wound transformer - Google Patents

Abstract

PURPOSE:To reduce the loss caused by eddy currents generated in lead cunductors largely by forming a lead by a second lead conductor constituted so as to fractionate a first lead-out conductor and a third extremely thin plate conductor and using the second lead conductor as an outgoing line. CONSTITUTION:A first lead-out conductor 71 is joined electrically with a third extremely thin plate-shaped conductor 73 in thickness of approximately 0.5mm through welding, etc. The third extremely thin plate-shaped conductor 73 is joined electrically with the winding-start or winding-end of a metallic sheet 8 shaping a foil-shaped winding through welding, etc. Since the radial component of the leakage flux 6 of the winding is increased extermely at both ends in the axial direction of the winding, the first and third conductors are formed in length within approximately 100mm from the ends in the axial direction of the winding, and insulating plates 74 having a thickness approximately the same as that of the third extremely thin plate-shaped conductor 73 are disposed to said sections.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to a foil winding using a foil winding formed by overlapping and winding a metal sheet such as copper or aluminum foil and an insulating sheet. The present invention relates to transformers, and in particular to foil-wound transformers with improved connection means between lead conductors and metal sheets.

(Prior Art) Foil-wound transformers have a good winding space factor, so they have the advantage of being able to be made smaller and lighter. It has already been put to practical use in small capacity transformers with relatively low voltages of several KV and several hundred KVA. Recently, in view of its excellent advantages, research has been conducted on its application to higher voltage/larger capacity transformers. The key points to consider are how to improve the cooling efficiency of the wire, give the winding a high insulation capacity, and how to reduce the heat generated at the connection between the lead conductor and the metal sheet. Among these problems, the cooling method for the windings in foil-wound transformers is to incorporate a cooling duct inside the windings, and by feeding a refrigerant with excellent insulation properties, the amount of heat generated from winding losses can be directly absorbed. A type of heat vibrator that is easy to cool is being considered. On the other hand, a means for reducing the heat generated at the connection portion between the lead conductor and the metal sheet has not yet been established.

In general, transformer windings have a gap between the low-voltage winding and high-voltage winding, and a main component in the axial direction of the winding, depending on the value of (current x number of turns) of the winding. A leakage magnetic flux is generated.

The flow of this leakage magnetic flux is as shown in FIG. That is, a foil-like metal sheet and an insulating sheet are layered and wound around an iron core 2 disposed in a tank 1 to form a low-voltage winding 3 and a high-voltage winding 4. Furthermore, lead conductors are fixed to the metal sheet 8 at the beginning and end of the windings 3 and 4.

The lead conductor 7 and the bushing 9 are connected by a 1° lead wire. In the foil-wound transformer having such a configuration, the leakage magnetic flux 6 is caused by the low voltage winding 3 as described above.
However, because the width of the metal sheet 8 is wide, eddy currents that try to cancel the magnetic flux in the radial direction of the winding incident on the metal sheet 8 Therefore, the magnetic flux 6 tends to flow from the end of the winding 5o■
At a point within 100 degrees, it suddenly turns in the direction of the winding diameter and heads toward the tank 1 and the iron core 2.

(Problem to be Solved by the Invention) By the way, in a foil-wound transformer, a flat plate with a rectangular cross section is generally used as the single outlet conductor 7, and its cross-sectional area is generally the same as, but larger than, the metal sheet 8. For example, if the metal sheet 8 has a thickness of 0.5 mm+ and a width of 2 m, the cross section of the single-outlet conductor 7 will be, for example, about 110 m x 100 mm. When the lead conductor 7 having such a large cross-sectional area is disposed at a portion of the winding end where magnetic flux is concentrated in the radial direction, a large eddy current flows inside the conductor to cancel out this magnetic flux. Further, when the current is taken out to the upper part of the winding by the lead conductor 7, the load current 11 of the metal sheet 8 flows concentratedly to the upper part as shown in FIG. The vicinity of the connection part A of the lead conductor 7 may become high in temperature due to the generated heat. Furthermore, this portion is the same as the portion where the eddy current 12 is generated in an attempt to cancel the radial magnetic flux 6 generated in the lead conductor 7.

The amount of heat generated is extremely large, leading to localized high temperatures, which may lead to melting damage. Furthermore, the eddy current flowing through the lead conductor 7 causes extra loss, reducing the operating efficiency of the transformer.

The present invention was proposed to solve the above-mentioned drawbacks of the conventional foil-wound transformer, and its purpose is to reduce the heat generated in the lead conductor and prevent melting damage at the connection between the metal sheet and the lead conductor. It is an object of the present invention to provide a highly reliable foil-wound transformer that prevents the eddy current loss from occurring in the lead conductor, and to provide a low-loss foil-wound transformer that significantly reduces eddy current loss generated in the lead conductor.

[Structure of the invention]

(Means for Solving the Problems) The foil-wound transformer of the present invention includes a first lead-out conductor having a rectangular cross section, a second lead-out conductor configured to subdivide the first lead-out conductor, and a third lead-out conductor configured to subdivide the first lead-out conductor. An output lead is formed with the ultra-thin flat conductor, and the second output conductor is used as a lead wire.

(Function) This greatly reduces the temperature rise due to eddy currents generated in the lead conductor, prevents melting of the lead conductor connection part, and significantly reduces resistance loss due to the eddy current, increasing the operating efficiency of the transformer. It is something that

(Example) Figures 1 to 5 show an example of the foil-wound transformer of the present invention.
This will be explained in detail with reference to the drawings. Note that the same parts as in the conventional type shown in FIGS. 6 and 7 are denoted by the same reference numerals.

FIG. 1 is a detailed view showing the structure of the lead lead according to the present invention. At the end of the first lead-out conductor 71 having a rectangular cross section and having a thickness Ti, a rectangular conductor having a width W2 that is approximately the same as the thickness T of the first lead-out conductor and a thickness T2 of approximately 1 inch is attached. A second lead-out conductor flap 2, which is constructed by stacking a plurality of conductors such that the thickness of the stack is approximately the same as the width W2 of the first lead-out conductor, is electrically connected by welding or the like.

Further, the first lead conductor 71 is electrically connected to a third extremely thin flat conductor 73 having a thickness of about 0.5 cm by welding or the like. The third ultra-thin flat conductor 73 is electrically connected to the beginning or end of the metal sheet 8 forming the foil winding by pressure welding or the like. Because the radial component of 6 is very large, the first and third conductors are approximately 10
An insulating plate 74 having a thickness approximately equal to that of the third ultra-thin flat conductor 73 is provided at that portion.
to be placed.

Figure 2 is a view taken along arrow B-B in Figure 1, and Figure 3 is a view of C in Figure 1.
-C sectional view.

A second lead conductor 72 is a conductor drawn out as a lead for the winding.

With the above configuration, the temperature rise θ of the lead lead due to the radial component of the leakage magnetic flux 6 of one winding is θ obtuse B"TW"
(''C) However, B: Magnetic flux density [Gauss] T: Conductor thickness [■] W: Conductor width [■] Since the relational expression holds true, the radius of the leakage magnetic flux 6 of the winding in the case of the conventional lead lead structure The temperature rise θ1 of the lead lead due to directional component B is θ, oc 73”・T1・W
l'', whereas in the case of the structure of the present invention, 0 m cc
B"-Wl-N a (ra)", where N is
This is the number of stacked wire conductors 72a forming the lead conductor 72. As described above, in the structure of the present invention, W.

Since JETl, NT, and teacher W1, θ2=θx/r
'r, and the temperature rise of the lead lead due to the radial component B of the leakage magnetic flux 6 of the winding is 115, since N is approximately 50 to 100.
It is reduced by 0 to 1/100.

At the same time, the resistance loss due to the eddy current generated in the lead lead is 1150~l since there is the same relational expression as the temperature rise θ due to the radial component B of the leakage magnetic flux 6 of the first winding.
/100.

A second lead conductor 72 that serves as a lead wire of the lead lead 7
In order to further enhance the effect of subdivision, as shown in FIG.
2b is applied.

FIG. 5 shows another embodiment of the cross-sectional shape of the second lead-out conductor, which is made of a rectangular wire having a width approximately half the thickness of the first lead-out conductor, and is stacked in two rows to form the first lead-out conductor. The diameter of the lead conductor is approximately the same as that of the lead conductor, and it is even more effective in reducing temperature rise and eddy current loss.

Although not shown, the same effect can be obtained when a rectangular transposed conductor or a composite stranded wire is used as the second lead conductor.

〔Effect of the invention〕

As explained above, according to the present invention, the second lead conductor has a rectangular cross section, the second lead conductor is configured to subdivide the first lead conductor, and the third ultra-thin flat conductor. By forming an outlet lead with a wire and using the second outlet conductor as the lead wire of the winding, the temperature rise due to eddy current generated in the outlet conductor is significantly reduced, and melting and damage at the outlet conductor connection part is prevented. A high-performance foil-wound transformer can be obtained, and a low-loss foil-wound transformer with significantly reduced eddy current loss generated in the lead conductor can be obtained.

[Brief explanation of drawings]

Fig. 1 is a detailed view showing the lead structure of the foil-wound transformer of the present invention, Fig. 2 is a cross-sectional view taken along line B-B in Fig. 1, and Fig. 3 is a cross-sectional view taken along line C-C in Fig. 1. Figure 4 is a detailed cross-sectional view of a lead-out conductor showing one embodiment of the present invention, Figure 5 is a detailed cross-sectional view of a lead-out conductor showing another embodiment of the present invention, and Figure 6 is a leakage magnetic flux in a foil-wound transformer. FIG. 7 is an enlarged view showing the connection between the lead conductor and the metal sheet in a conventional foil-wound transformer. 2... Iron core 3, 4... Winding 8... Metal sheet 71.72... Lead conductor 73...
Flat conductor 74... Insulating plate agent Patent attorney Rule Ken Chika Yudo Hirofumi Mitsumata Figure 1 Figure 4 Figure 5v! J Figure 6 Figure 7

Claims (5)

[Claims] (1) In a foil-wound transformer using a foil winding in which a metal sheet and an insulating sheet are overlapped and wound around an iron core, the first lead-out conductor has a rectangular cross section, and the width is approximately equal to the thickness of the first lead-out conductor. A second lead-out conductor configured by stacking a plurality of rectangular conductors of the same size so that the thickness of the stack is approximately the same as the width of the first lead-out conductor, and electrically connected to the first lead-out conductor. and an output lead is formed of a third ultra-thin flat conductor having approximately the same length as the length of the first output conductor and electrically connected to the first output conductor; A foil-wound transformer characterized in that a conductor is electrically connected to the metal sheet and the second conductor is used as a lead wire. (2) The second conductor is composed of a rectangular wire having a width approximately half the thickness of the first lead-out conductor, and is stacked in two rows so that the dimensions are approximately the same as the first lead-out conductor. A foil-wound transformer according to claim 1. (3) The foil-wound transformer according to claim 1, wherein the second conductor is a rectangular transposed conductor. (4) The first and second conductors and the first and third conductors are each joined by welding, and the third conductor and the metal sheet are joined by pressure welding. foil-wound transformer. (5) The foil-wound transformer according to claim 1, wherein the second lead-out conductor is base-insulated.