JP2023099243A - welding transformer - Google Patents

Abstract

To provide a welding transformer capable of suppressing a drop in dielectric strength between a primary coil and a secondary coil.SOLUTION: A welding transformer 100 includes: a primary coil 10 on which a plurality of primary side unit coils 11 is laminated; a secondary coil 20 in which a plurality of secondary unit coils 21 is laminated; and a magnetic core 40. Each of the primary and secondary unit coils 11, 21 has a body portion 12, 22 having a plurality of corner portions 13, 23 and first terminal portions 14, 24 and second terminal portions 15, 25 extending from respective ends of the main body portions 12, 22 with a space therebetween. Concave portions 13a and 23a directed toward an outer circumference are provided on the inner peripheral surfaces of the plurality of corner portions 13 and 23, respectively. Primary side unit coils 11 and secondary side unit coils 21 are alternately laminated while being insulated from each other.SELECTED DRAWING: Figure 5A

Description

The present disclosure relates to welding transformers.

2. Description of the Related Art Conventionally, in a welding transformer, a configuration is known in which primary coils and secondary coils are alternately laminated in order to reduce leakage inductance (see Patent Documents 1, 2, and 4).

In addition, a technique is widely known in which a plurality of one-turn coils (hereinafter sometimes referred to as unit coils) made of metal plate material are laminated to form a primary side coil and a secondary side coil, respectively, and applied to a welding transformer. ing. In this case, in order to ensure dielectric strength between the primary coil and the secondary coil, the primary coil and the secondary coil are configured by sandwiching an insulating sheet between each of the plurality of unit coils. A configuration is known (see Patent Documents 3 and 4).

Japanese Patent Application Laid-Open No. 2004-200458 JP-A-2000-223320 JP 2005-277269 A JP-A-2002-175922

By the way, as disclosed in Patent Documents 3 and 4, by alternately stacking the unit coils of the primary side coil and the unit coils of the secondary side coil, the leakage inductance can be greatly reduced.

However, in such a configuration, simply providing an insulating sheet between the unit coils of the primary coil and the unit coils of the secondary coil does not result in sufficient insulation between the primary coil and the secondary coil. It has been clarified by the studies of the inventors of the present application that the dielectric strength voltage may be lowered.

The present disclosure has been made in view of this point, and an object thereof is to provide a welding transformer capable of suppressing a decrease in withstand voltage between a primary coil and a secondary coil.

In order to achieve the above object, a welding transformer according to the present disclosure includes a primary side coil in which a plurality of primary side unit coils made of plate-shaped conductors are laminated, and a plurality of secondary side unit coils made of plate-shaped conductors. At least a laminated secondary coil and a magnetic core disposed inside the primary coil and the secondary coil, wherein the primary unit coil and the secondary unit coil are: A substantially annular main body portion having a plurality of corner portions, and a first terminal portion and a second terminal portion drawn out from both ends of the main body portion and extending in parallel and in the same direction with a space therebetween, respectively. The inner peripheral surface of each of the plurality of corner portions is provided with a concave portion recessed toward the outer peripheral side, and the primary unit coil and the secondary unit coil are insulated from each other. It is characterized by being alternately laminated in a state.

According to the present disclosure, it is possible to suppress a decrease in withstand voltage between the primary coil and the secondary coil.

1 is a perspective view of a welding transformer according to an embodiment viewed from a primary side external terminal; FIG. It is the perspective view which looked at the welding transformer from the secondary side external terminal. FIG. 3 is an exploded perspective view of a main part of the welding transformer; FIG. 3 is an exploded perspective view of a magnetic core; 4 is a plan view of a first unit coil; FIG. FIG. 4 is a plan view of a second unit coil; FIG. 4 is an exploded schematic diagram of a portion surrounded by a dashed line shown in the upper left of FIG. 3; It is a top view of a secondary side unit coil. FIG. 4 is an exploded schematic diagram of a portion surrounded by a dashed line shown in the lower right of FIG. 3;

Hereinafter, embodiments of the present disclosure will be described in detail based on the drawings. The following description of preferred embodiments is merely exemplary in nature and is in no way intended to limit the disclosure, its applicability or its uses.

(Embodiment 1)
[Construction of Welding Transformer]
FIG. 1 shows a perspective view of a welding transformer according to an embodiment viewed from a primary side external terminal, and FIG. 2 shows a perspective view viewed from a secondary side external terminal. FIG. 3 shows an exploded perspective view of the main part of the welding transformer, and FIG. 4 shows an exploded perspective view of the magnetic core.

1 to 4, the side on which the holding plate 51 of the fixture 50 shown in FIG. 1 is provided is called the upper side, and the opposite side, on which the support plate 52 is provided, is called the lower side. Sometimes.

As shown in FIGS. 1 and 2, the welding transformer 100 has a primary coil 10, a secondary coil 20, a magnetic core 40, and a fixture 50. As shown in FIGS. Welding transformer 100 is used, for example, as a voltage converter of a welding inverter power source (not shown).

As shown in FIGS. 1 and 3, the primary side coil 10 is configured as a unit circuit for each of four primary side unit coils 11 connected in series. Also, this unit circuit has five external terminals. In the example shown in FIG. 1, the primary coil 10 includes two unit circuits, but is not particularly limited to this. The number of unit circuits included in the primary coil 10 may be one, or three or more. It can be changed as appropriate according to the specifications required for the welding transformer 100 . The primary side unit coil 11 is a one-turn coil made of a copper plate. This will be detailed later. Also, the manner in which the four primary side unit coils 11 are connected will be described later.

The primary side coil 10 is a so-called high voltage side coil that is connected to an external power supply such as an external commercial power supply. By changing the combination of two of the five primary external terminals 10a to 10e connected to the external power supply, the number of turns of the primary coil 10 in the unit circuit is changed. For example, when connecting the primary side external terminal 10a and the primary side external terminal 10e to an external power supply, the number of turns of the primary side coil 10 in the unit circuit is four. On the other hand, when the primary external terminal 10a and the primary external terminal 10b are connected to an external power supply, the number of turns of the primary coil 10 in the unit circuit is one. Depending on the specifications required for welding transformer 100, it is possible to change the combination of two terminals connected to the external power supply, and thus the number of turns of primary coil 10 in the unit circuit.

The secondary coil 20 is configured as a unit circuit for each of four secondary unit coils 21 . This unit circuit also has three secondary external terminals 20a to 20c. The secondary external terminals 20a to 20c are provided with external connection holes 20a1 to 20c1 to which wirings for connection with other circuits are connected.

The number of unit circuits included in the secondary coil 20 is basically the same as the number of unit circuits included in the primary coil 10 . As with the primary unit coil 11, the secondary unit coil 21 is also a one-turn coil made of a copper plate. This will be detailed later. Also, the manner in which the four secondary unit coils 21 are connected will be described later.

The secondary side coil 20 is a so-called low-voltage side coil connected to internal busbar wiring (not shown) of an inverter power supply or an internal circuit (not shown) such as a semiconductor power converter. Of the secondary external terminals 20a to 20c, by changing the combination of two terminals connected to the internal bus bar wiring of the inverter power supply on the output side or the internal circuit, the secondary coil 20 in the unit circuit can be changed. Change the number of turns. For example, when connecting the secondary external terminal 20a and the secondary external terminal 20c to the output side, the number of turns of the secondary coil 20 in the unit circuit is four. On the other hand, when connecting the secondary external terminal 20a and the secondary external terminal 20b to the output side, the number of turns of the primary coil 10 in the unit circuit is two. Similarly, when the secondary external terminal 20c and the secondary external terminal 20b are connected to the output side, the number of turns of the primary coil 10 in the unit circuit is two. That is, the secondary external terminal 20b corresponds to an intermediate tap terminal. Depending on the specifications required for welding transformer 100, it is possible to change the combination of two terminals connected to the output side, and thus the number of turns of secondary coil 20 in the unit circuit.

As shown in FIG. 4, the magnetic core 40 is configured by combining two E-shaped cores 41 and 42 . In practice, four magnetic cores 40 are arranged in parallel. However, it is not particularly limited to this, and the number of magnetic cores 40 to be used can be appropriately changed according to the size of the welding transformer 100 , particularly the size of the primary coil 10 and the secondary coil 20 .

The E-shaped core 41 is made of a magnetic material such as ferrite, and has three protrusions 41a to 41c and grooves 41d and 41e provided therebetween. The E-shaped core 42 is made of a magnetic material such as ferrite, and has three projections 42a to 42c and grooves 42d and 42e provided therebetween. The convex portions 41 b and 42 b are arranged inside the primary coil 10 and the secondary coil 20 . Two opposite sides of the body portions 12 and 22 (see FIGS. 5A, 5B and 7) of the primary coil 10 and the secondary coil 20 are accommodated in the grooves 41d and 42d and the grooves 41e and 42e, respectively. .

Although the magnetic core 40 is not shown in FIG. 3, a cylindrical insulating sheet 31 is arranged inside the primary coil 10 and the secondary coil 20 along the inner peripheral surfaces thereof. By doing so, insulation between the magnetic core 40 and the primary coil 10 and the secondary coil 20 is ensured.

The fixture 50 has a pressing plate 51 and a support plate 52 . A laminated body of the primary coil 10 and the secondary coil 20 in which the magnetic core 40 is incorporated is placed on the support plate 52, and the laminated body is pressed by the pressing plate 51 from above and screwed or the like. The holding plate 51 is connected to the support plate 52 . By doing so, the laminated body of the primary coil 10 and the secondary coil 20 in which the magnetic core 40 is incorporated is held and fixed.

[Configuration of primary and secondary unit coils]
FIG. 5A shows a plan view of the first unit coil, and FIG. 5B shows a plan view of the second unit coil. FIG. 6 shows an exploded schematic view of the part surrounded by the dashed line shown in the upper left of FIG. FIG. 7 shows a plan view of a secondary unit coil, and FIG. 8 shows a schematic diagram of an exploded portion surrounded by a dashed line shown in the lower right of FIG.

As shown in FIG. 3 , the primary unit coil 11 includes a first unit coil 111 and a second unit coil 112 . Further, as shown in FIG. 6, the first unit coil 111 is formed by a set of a plurality of copper plates 111a (for example, three) having the same shape. Each thickness of the copper plate 111a is about 0.4 mm to 1.0 mm. Insulating sheets 32 are sandwiched between the three copper plates 111a that are superimposed. A laminate of three copper plates 111a and two insulating sheets 32 shown in FIG. 6 is wrapped with an insulating sheet 33 and further wrapped with an insulating sheet 30 to form the first unit coil 111 shown in FIG.

Moreover, although not shown, the second unit coil 112 is also formed as a set of a plurality of copper plates (for example, three) having the same shape. The thickness of each copper plate is also the same as the thickness of the copper plate 111a. An insulating sheet 32 is sandwiched between each of the three laminated copper plates, and the laminate is further wrapped with an insulating sheet 33 and further wrapped with an insulating sheet 30 to form the second unit coil 112 shown in FIG. be done.

The number of copper plates included in each of the first unit coil 111 and the second unit coil 112 is not particularly limited to the example shown in FIG. It can be changed as appropriate according to the number of turns of .

Also, the first unit coil 111 and the second unit coil 112 are obtained by punching a copper plate, for example. Alternatively, the first unit coil 111 and the second unit coil 112 may be formed by bending a rectangular copper wire in the edgewise direction. However, in this case, a recess 13a and terminal holes 14a and 15a, which will be described later, are formed by performing different processing.

Moreover, as shown in FIGS. 5A and 5B, the first unit coil 111 and the second unit coil 112 each have a body portion 12, a first terminal portion 14, and a second terminal portion 15. As shown in FIGS.

The main body portion 12 has a substantially square annular shape and has four corner portions 13 . In addition, recessed portions 13a that are recessed toward the outer peripheral side are formed on the inner peripheral surfaces of the four corner portions 13, respectively. The concave portion 13 a is formed so that the four corner portions 13 have the same radius of curvature R of the concave portion 13 a when viewed from above. In other words, the recess 13a is formed such that the body portion 12 is removed within the range of the same distance R from the top of the inner peripheral side of the corner portion 13 when the recess 13a is not formed. The concave portion 13a is formed to have the same curvature radius R in each of the first unit coil 111 and the second unit coil 112 . In addition, in the first unit coil 111 and the second unit coil 112, the outer shape and size of each main body portion 12 are set to be substantially the same.

The first terminal portion 14 and the second terminal portion 15 are pulled out from both ends of the main body portion 12 and arranged side by side with a space therebetween in the same direction. 12 and extends in the opposite direction.

As shown in FIGS. 5A and 5B , the arrangement of the first terminal portion 14 and the second terminal portion 15 differs between the first unit coil 111 and the second unit coil 112 .

As shown in FIG. 5A , the second terminal portion 15 of the first unit coil 111 is a portion extending from one side end of the body portion 12 . Further, the first terminal portion 14 extends in parallel with the second terminal portion 15 with a space therebetween from the end portion of another side of the body portion 12 extending in the direction intersecting the second terminal portion 15 .

On the other hand, as shown in FIG. 5B, in the second unit coil 112, both ends of the body portion 12 are spaced apart from each other on one side of the body portion 12 that intersects the extending direction of the first terminal portion 14 and the second terminal portion 15. They are set apart from each other. A first terminal portion 14 extends from one end of the body portion 12, and a second terminal portion 15 extends from the other end in parallel.

When the first unit coil 111 and the second unit coil 112 are arranged such that the main body portions 12 of the first unit coil 111 and the second unit coil 112 overlap each other, the first terminal portion 14 of the first unit coil 111 corresponds to the first terminal portion 14 of the second unit coil 112 in plan view. It is provided at a position overlapping the second terminal portion 15 . In other words, the first unit coil 111 is arranged so that the terminal hole 14a provided in the first terminal portion 14 of the first unit coil 111 and the terminal hole 15a provided in the second terminal portion 15 of the second unit coil 112 overlap each other. The arrangement of the second terminal portions 15 of the second unit coil 112 is set for the first terminal portions 14 of the coil 111 respectively.

In addition, when two second unit coils 112 are arranged so that the two second unit coils 112 are turned upside down and the respective body portions 12 overlap each other, in plan view, the first terminal portion 14 of one of the second unit coils 112 is It is provided at a position overlapping the first terminal portion 14 of the other second unit coil 112 . In other words, the terminal hole 14a provided in the first terminal portion 14 of one of the second unit coils 112 and the terminal hole 14a provided in the first terminal portion 14 of the other second unit coil 112 overlap each other. , the arrangement of the first terminal portions 14 of the second unit coils 112 is set.

The secondary unit coil 21 shown in FIGS. 7 and 8 is formed as a set of a plurality of same-shaped copper plates 21a (for example, two), like the first unit coil 111 and the second unit coil 112. FIG. Each thickness of the copper plate 21a is about 0.4 mm to 1.0 mm. An insulating sheet 32 is sandwiched between the two copper plates 21a that are superimposed. The laminate of two copper plates 111a and one insulating sheet 32 shown in FIG. 8 is further wrapped with an insulating sheet 33 to form the secondary unit coil 21 shown in FIG.

The number of copper plates 21a included in the secondary unit coil 21 is not particularly limited to the example shown in FIG. It can be changed as appropriate. Also, the secondary unit coil 21 is manufactured by the same method as the first unit coil 111 and the second unit coil 112 described above. Further, the secondary unit coil 21 shown in FIG. 3 is configured by stacking two planar coils shown in FIG. However, it is not particularly limited to this, and can be changed as appropriate according to the range of electrical resistance and current allowed for the secondary coil 20 . For example, the secondary unit coil 21 may be composed of only one planar coil shown in FIG. It goes without saying that this also applies to the primary side unit coil 11 . For example, the first unit coil 111 may be configured by stacking two planar coils shown in FIG. 5A. The second unit coil 112 may be configured by stacking two planar coils shown in FIG. 5B.

In addition, as shown in FIG. 7, the secondary unit coil 21 has a main body portion 22, a first terminal portion 24, and a second terminal portion 25, as in the case of the first unit coil 111 and the second unit coil 112, respectively. have.

The shape of the body portion 22 and the provision of recesses 23 a on the inner peripheral surfaces of the four corner portions 23 are also the same as those of the first unit coil 111 and the second unit coil 112 . In addition, the curvature radius R of the recessed portion 23a is the same for the four corner portions 23, in other words, the main body is in the range of the same distance R from the inner peripheral side top portion of the corner portion 23 when the recessed portion 23a is not formed. Similarly to the first unit coil 111 and the second unit coil 112, the concave portion 23a is formed so that the portion 22 is removed. The concave portion 23 a of the secondary unit coil 21 is formed so that the curvature radius R is the same as the curvature radius R of the concave portions 13 a of the first unit coil 111 and the second unit coil 112 . Also, in the secondary unit coil 21 , the outer shape and size of the body portion 22 are set to be substantially the same as those of the first unit coil 111 and the second unit coil 112 .

The first terminal portion 24 and the second terminal portion 25 are pulled out from both ends of the main body portion 22 and arranged in parallel in the same direction, in this case, on the opposite side of the main body portion 22 with both ends of the main body portion 22 interposed therebetween. extends to

As shown in FIG. 7 , the second terminal portion 25 of the secondary unit coil 21 is a portion extending from one end of the body portion 22 . Further, the first terminal portion 24 extends in parallel with the second terminal portion 25 with a space therebetween from the end of another side of the main body portion 22 extending in the direction intersecting the second terminal portion 25 .

When the two secondary unit coils 21 are turned upside down and arranged such that the respective body portions 22 overlap each other, in a plan view, the second terminal portion 25 of one of the secondary unit coils 21 is It is provided at a position overlapping the first terminal portion 24 of the other secondary unit coil 21 . Furthermore, the terminal hole 25a provided in the second terminal portion 25 of one secondary unit coil 21 and the terminal hole 24a provided in the first terminal portion 24 of the other secondary unit coil 21 overlap. , the arrangement of the first terminal portion 24 and the second terminal portion 25 of the secondary unit coil 21 are respectively set.

[Configuration of primary and secondary coils]
As shown in FIG. 3 , the primary side unit coil 11 is covered with an insulating sheet 30 . Further, an insulating sheet 32 is sandwiched between each of the plurality of copper plates of the primary unit coil 11 and the secondary unit coil 21 described above. A laminate of one or a plurality of insulating sheets 32 and a plurality of copper plates is covered with an insulating sheet 33 . In this case, although not shown, the insulating sheet 33 is formed by cutting a sheet of insulating paper at a plurality of locations. The number, position and length of the cuts correspond to the respective shapes of the primary unit coil 11 and the secondary unit coil 21, and the insulating sheet 33 is bent at the cuts to form the primary unit coil 11. and the secondary unit coil 21 respectively. By doing so, the surfaces of the primary side unit coils can be completely covered with the insulating sheets 33 and 30 except for the first terminal portions 14 and 24 and the second terminal portions 15 and 25. can. In addition, each surface of the secondary unit coil 21 can be completely covered with the insulating sheet 33 .

The insulating sheet 30 covering the primary unit coil 11 is provided with a folded portion 30a, and a part of the secondary unit coil 21 covered with the insulating sheet 33 is wrapped in the folded portion 30a. However, providing the folded portion 30a is not essential and may be omitted.

As is clear from FIG. 3, the primary unit coils 11 and the secondary unit coils 21 are alternately laminated while being insulated from each other by the insulating sheets 30 .

The first unit coil 111 and the second unit coil 112 that constitute the primary coil 10 are arranged as follows.

From the top, the first unit coils 111 are arranged on the first and fourth layers, and the second unit coils 112 are arranged on the second and third layers, respectively. In addition, the first unit coil 111 arranged on the fourth sheet is arranged face down with respect to the first unit coil 111 arranged on the first sheet, and the first unit coil 111 arranged on the third sheet is , is arranged face down with respect to the first unit coil 111 arranged on the second sheet.

By arranging the first unit coil 111 and the second unit coil 112 in this manner, first, the first terminal portion 14 of the fourth first unit coil 111 and the first terminal portion 14 of the third second unit coil 112 The two terminal portions 15 can be overlapped when viewed from the top so that the terminal holes 14a and 15a formed in the respective portions overlap. The primary side external terminal 10b can be formed by passing a screw or the like (not shown) through the two terminal holes 14a and 15a and fastening them. Similarly, the first terminal portion 14 of the third second unit coil 112 and the first terminal portion 14 of the second second unit coil 112 are overlapped in top view, and the primary side external terminal 10c is connected. can be formed. The second terminal portion 15 of the second unit coil 112 of the second sheet and the first terminal portion 14 of the first unit coil 111 of the first sheet are overlapped in top view to form the primary side external terminal 10d. can be done. The second terminal portion 15 of the fourth first unit coil 111 constitutes the primary external terminal 10a, and the second terminal portion 15 of the first unit coil 111 constitutes the primary external terminal 10e. configure.

By doing so, it is possible to easily form a structure in which four primary side unit coils 11 are connected in series using only two types of first unit coil 111 and second unit coil 112 .

Secondary unit coils 21 forming the secondary coil 20 are arranged as follows.

The secondary unit coils 21 arranged in the first and second sheets are arranged so that the front and back sides are oriented in the same order from the top. The secondary unit coils 21 arranged in the third and fourth sheets are arranged so that the front and back faces are oriented in the same direction. On the other hand, the secondary unit coils 21 arranged on the second and third sheets are arranged upside down.

By arranging the four secondary unit coils 21 in this manner, first, the second terminal portion 25 of the fourth secondary unit coil 21 and the second terminal portion 25 of the third secondary unit coil 21 are connected. When viewed from above, the terminal portions 25 can be superimposed so that the terminal holes 25a formed in the respective portions overlap each other. By passing the bolts 61 through the two terminal holes 25a and through holes (not shown) provided in the secondary external terminals 20a and tightening them, as shown in FIG. can be connected to the second terminal portion 25 of the secondary unit coil 21 and the secondary external terminal 20a.

Similarly, the first terminal portion 24 of the fourth secondary unit coil 21 and the first terminal portion 24 of the third secondary unit coil 21 are overlapped in top view, and bolts 61, washers 62 and The nuts 63 can be used to connect the first terminal portions 24 of the third and fourth secondary unit coils 21 and the secondary external terminals 20b. Moreover, by doing so, a parallel connection structure 26 is formed in which the third secondary unit coil 21 and the fourth secondary unit coil 21 are connected in parallel.

In addition, the first terminal portions 24 of the second and first secondary unit coils 21 are shown in top view with respect to the first terminal portions 24 of the third and fourth secondary unit coils 21 . The terminal holes 24a can be overlapped with each other. Therefore, bolts 61, washers 62 and nuts 63 are used to connect the first terminal portions 24 of the first to fourth secondary unit coils 21 and the secondary external terminals 20b as shown in FIG. be able to.

The second terminal portion 25 of the second secondary unit coil 21 and the second terminal portion 25 of the first secondary unit coil 21 are superimposed in top view, and terminal holes 25a provided in each can overlap. By fastening bolts 61 through the two terminal holes 25a and a through hole (not shown) provided in the secondary external terminal 20c, as shown in FIG. can be connected to the second terminal portion 25 of the secondary unit coil 21 and the secondary external terminal 20c.

Moreover, by doing so, a parallel connection structure 26 is formed in which the first secondary unit coil 21 and the second secondary unit coil 21 are connected in parallel. Also, two sets of parallel connection structures 26 are connected in series.

[Effects, etc.]
As described above, the welding transformer 100 according to the present embodiment includes the primary coil 10 in which a plurality of primary unit coils 11 made of copper plates are laminated, and the secondary unit coils 21 in which a plurality of copper plates are laminated. and a magnetic core 40 in which convex portions 41 b and 42 b are arranged inside the primary coil 10 and the secondary coil 20 .

The primary unit coil 11 includes a substantially annular main body portion 12 having a plurality of corner portions 13, and first terminal portions 14 drawn out from both ends of the main body portion 12 and extending in the same direction in parallel with each other at intervals. and a second terminal portion 15, respectively. A recessed portion 13 a recessed toward the outer peripheral side is provided on the inner peripheral surface of each of the plurality of corner portions 13 .

The secondary unit coil 21 includes a substantially annular main body portion 22 having a plurality of corner portions 23, and first terminal portions 24 drawn out from both ends of the main body portion 22 and extending in the same direction in parallel with each other at intervals. and a second terminal portion 25, respectively. A recessed portion 23 a recessed toward the outer peripheral side is provided on the inner peripheral surface of each of the plurality of corner portions 23 .

In addition, the primary unit coils 11 and the secondary unit coils 21 are alternately laminated while being insulated from each other.

By configuring the welding transformer 100 in this way, it is possible to suppress a decrease in dielectric strength voltage between the primary coil 10 and the secondary coil 20 . This will be further explained.

If the concave portions 13a, 23a are not provided, the inner peripheral surfaces of the corner portions 13, 23 of the primary unit coil 11 and the secondary unit coil 21, respectively, have a right angle contour or a radius of curvature of The curved surface is small and the outline is almost right angle. In this case, if the insulating sheets 30 and 33 are simply provided between the primary unit coil 11 and the secondary unit coil 21, the insulating sheets may not be formed on the inner peripheral surfaces, particularly on the top portions, of the corner portions 13 and 23. It becomes difficult to bring 30 and 33 into close contact. Then, in the primary side unit coil 11 and the secondary side unit coil 21 adjacent to each other in the stacking direction, the dielectric strength voltage is lowered at the corner portions 13 and 23 . As a result, there is a risk that the dielectric strength voltage between the primary coil 10 and the secondary coil 20 will decrease.

On the other hand, according to the present embodiment, at the corner portions 13 and 23 of the primary unit coil 11 and the secondary unit coil 21, respectively, recesses 13a and 23a that are recessed toward the outer peripheral side are provided on the inner peripheral surface. , the insulating sheets 30, 33 can be easily adhered to the inner peripheral surfaces of the corner portions 13, 23.

As a result, it is possible to reliably secure insulation between the primary unit coil 11 and the secondary unit coil 21 that are adjacent in the stacking direction. It is possible to suppress a decrease in dielectric strength voltage.

The surfaces of the primary unit coil 11 and the secondary unit coil 21 are wrapped with insulating sheets 30 and 33, respectively, except for the first terminal portions 14 and 24 and the second terminal portions 15 and 25, respectively. By doing so, the primary unit coil 11 and the secondary unit coil 21 adjacent to each other in the stacking direction are insulated from each other, and the primary unit coil 11 and the secondary unit coil 21 are insulated. can shorten the distance for As a result, the primary coil 10 and the secondary coil 20 can be reliably insulated, and the size of the welding transformer 100 can be reduced. As disclosed in Patent Document 1, by using the insulating sheets 30 and 33 having a plurality of cuts, the surfaces of the primary unit coil 11 and the secondary unit coil 21 are reliably wrapped and covered. be able to.

Moreover, according to this embodiment, it is possible to reduce the influence of the so-called skin effect, in which the current concentrates only on the surface of the coil.

As the influence of the skin effect generated in the coil increases, the temperature of the coil increases, and accordingly, the power loss in welding transformer 100 also increases.

On the other hand, according to this embodiment, each of the plurality of copper plates 111 a included in the first unit coil 111 is covered with the insulating sheet 32 . Each of the plurality of copper plates included in second unit coil 112 is covered with insulating sheet 32 . Furthermore, each of the plurality of copper plates 21 a included in the secondary unit coil 21 is covered with an insulating sheet 32 .

By doing so, the skin effect can be suppressed, and an increase in the temperature of the coil and, in turn, an increase in power loss in the welding transformer 100 can be suppressed.

Further, according to the present embodiment, the primary coil 10 has a structure in which a plurality of primary unit coils 11 made of copper plates are laminated, and the secondary coil 20 has a structure in which a plurality of secondary unit coils 21 made of copper plates are laminated. It is assumed that the structure is Further, the primary side unit coils 11 and the secondary side unit coils 21 are alternately laminated while being insulated from each other.

By doing so, the leakage inductance in welding transformer 100 can be reduced, and a decrease in voltage conversion efficiency in welding transformer 100 can be suppressed.

The primary side coil 10 forms a unit circuit by connecting four primary side unit coils 11 in series. The secondary coil 20 has two sets of parallel connection structures 26 in which two secondary unit coils 21 are connected in parallel, and the two sets of parallel connection structures 26 are connected in series to form a unit circuit. ing.

The primary coil 10 has five primary external terminals 10a to 10e, and the secondary coil 20 has three secondary external terminals 20a to 20c.

By configuring the primary side coil 10 in this way, a combination of two of the five primary side external terminals 10a to 10e connected to the external power supply can be selected according to the specifications required for the welding transformer 100. By changing, the number of turns of the primary coil 10 in the unit circuit can be changed. In addition, by configuring the secondary coil 20 in this way, two of the three secondary external terminals 20a to 20c connected to the output side can be connected according to the specifications required for the welding transformer 100. By changing the combination, the number of turns of the secondary coil 20 in the unit circuit can be changed.

The primary unit coil 11 is composed of two types of unit coils, a first unit coil 111 and a second unit coil 112 .

When the first unit coil 111 and the second unit coil 112 are arranged such that the main body portions 12 of the first unit coil 111 and the second unit coil 112 overlap each other, the first terminal portion 14 of the first unit coil 111 corresponds to the first terminal portion 14 of the second unit coil 112 in plan view. It is provided at a position overlapping the second terminal portion 15 .

In addition, when two second unit coils 112 are arranged so that the two second unit coils 112 are turned upside down and the respective body portions 12 overlap each other, in plan view, the first terminal portion 14 of one of the second unit coils 112 is It is provided at a position overlapping the first terminal portion 14 of the other second unit coil 112 .

By doing so, first, the primary coil 10 having a structure in which four primary coil units 11 are connected in series can be manufactured at low cost. For example, Patent Documents 2 and 3 also disclose a structure in which four unit coils are connected in series. However, in these cases, it is necessary to prepare four types of unit coils because the positions of the terminal portions are different for each unit coil.

On the other hand, according to this embodiment, compared with the configurations disclosed in Patent Documents 2 and 3, the number of types of primary side unit coils 11 can be reduced. Further, by providing the first terminal portion 14 and the second terminal portion 15 in each of the first unit coil 111 and the second unit coil 112 as described above, it becomes easy to adjust the arrangement between different coils. Assembly of the side coil 10 is simplified.

In addition, when two secondary unit coils 21 are arranged so that the two secondary unit coils 21 are turned upside down and the respective body portions 22 overlap, the second terminal portion 25 of one of the secondary unit coils 21 is viewed from above. is provided at a position overlapping the first terminal portion 24 of the other secondary unit coil 21 .

By doing so, the secondary unit coil 21 can be of one type, and arrangement adjustment between different coils is facilitated. Assembly is simplified.

In this embodiment, the case where the primary unit coil 11 and the secondary unit coil 21 are each made of a copper plate has been described as an example. Materials other than copper may be used depending on the range of electrical resistance. In other words, the primary unit coil 11 and the secondary unit coil 21 may each be a plate-shaped conductor.

Moreover, the above-mentioned skin effect occurs remarkably when the current flowing through the coil is a high-frequency current or a large current, or when both of them are satisfied.

In a welding inverter power supply used for arc welding, etc., the inverter frequency is several tens of kHz to several hundred kHz, for example, about 40 kHz to 150 kHz, and the output current is about several tens of A (amperes) to several hundred A (amperes). There are many things. In addition, demands for miniaturization and high efficiency of inverter power sources for welding are increasing.

The welding transformer 100 of the present embodiment is suitable for such an inverter power supply for welding because the skin effect can be reduced and the size of the primary coil 10 and the secondary coil 20 can be reduced.

The welding transformer of the present disclosure is suitable for application to a welding power source that outputs high-frequency current.

10 Primary side coils 10a to 10d Primary side external terminal 11 Primary side unit coil 12 Body portion 13 Corner portion 13a Recess 14 First terminal portion 15 Second terminal portion 20 Secondary side coils 20a to 20c Secondary side external terminal 21 Secondary side unit coil 22 Body portion 23 Corner portion 23a Recess 24 First terminal portion 25 Second terminal portion 26 Parallel connection structure 30, 31, 32, 33 Insulating sheet 40 Magnetic cores 41, 42 E-shaped core 50 Fixed Tool 51 Pressing plate 52 Supporting plate 61 Bolt 62 Washer 63 Nut 100 Welding transformer 111 First unit coil 112 Second unit coil

Claims (4)

a primary coil in which a plurality of primary unit coils made of plate-shaped conductors are laminated;
a secondary coil in which a plurality of secondary unit coils made of plate-shaped conductors are laminated;
At least a magnetic core disposed inside the primary coil and the secondary coil,
The primary unit coil and the secondary unit coil are
a substantially annular body portion having a plurality of corner portions;
each having a first terminal portion and a second terminal portion drawn out from both ends of the main body portion and extending in the same direction in parallel with a space therebetween;
The inner peripheral surface of each of the plurality of corner portions is provided with a recess that is recessed toward the outer peripheral side,
A welding transformer, wherein the primary side unit coil and the secondary side unit coil are alternately laminated while being insulated from each other. The welding transformer according to claim 1,
The primary coil comprises four primary unit coils connected in series to form a unit circuit,
The secondary coil has two sets of parallel connection structures in which two secondary unit coils are connected in parallel, and the two sets of parallel connection structures are connected in series to form a unit circuit. Welding transformer characterized by: In the welding transformer according to claim 2,
The primary coil has five external terminals for each unit circuit, and by changing the combination of two external terminals connected to an external power supply among the five external terminals, The number of turns of the primary coil at is changed,
The secondary coil has three external terminals, and by changing the combination of the two external terminals connected to the output side, the number of turns of the secondary coil in the unit circuit is changed. A welding transformer characterized by: The welding transformer according to any one of claims 1 to 3,
A welding transformer, wherein a surface of each of the plurality of primary side unit coils and the plurality of secondary side unit coils is covered with an insulating sheet.

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