Transformer

Abstract

To improve the productivity of a transformer using a unicore.SOLUTION: In the transformer, a unicore is provided. The butt joint of the innermost block of the unicore is located at one position in the yoke part, and the butt joints outside the innermost block are located at two positions in the leg parts of the unicore.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a transformer. [Background technology]

[0002] Transformers that change the voltage of AC power are composed of an iron core, a coil, and metal fittings that hold these in place and make the transformer a rigid body. Iron cores are broadly divided into wound cores and stacked cores. Wound cores are typically made by winding thin electromagnetic steel sheets, 0.20 to 0.35 mm thick, into a shape consisting of straight sections and R sections, resulting in a certain stack thickness. When viewed from a direction that allows the stack thickness to be seen, they are configured as a hollow, approximately rectangular shape, with rounded corners when viewed from a direction that allows the stack thickness to be seen.

[0003] Because distortion occurs in this R section, leading to increased loss, normal wound cores undergo stress relief annealing. In contrast, a structure called Unicore creates corners by straight bending instead of R sections. As a result, the area where the R section of a normal wound core would be is bent once at 90°C, twice at 45°C, and three times at 30°C, etc., through bending processes, which localize distortion and minimize loss deterioration, making annealing unnecessary. This reduces the power consumption of the furnace required for annealing, making this a wound core structure that is expected to reduce environmental impact.

[0004] Unicores with this structure are manufactured by bending each electromagnetic steel sheet multiple times and cutting it once by machine, and then stacking each sheet that has been shaped by hand. Therefore, even though annealing is not required, the core manufacturing lead time is longer than that of a regular wound core, in which the sheet is cut at high speed, wound to the specified thickness, and then annealed inside a rectangular jig. Furthermore, Unicores have higher losses when not annealed compared to regular wound cores made from electromagnetic steel sheets of the same steel type. For these reasons, Unicores are not widely used in Japan.

[0005] A known example that discloses Unicore is Patent Document 1. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-70241 Summary of the Invention [Problem to be solved by the invention]

[0007] Unicore also does not require annealing, so it has the potential to achieve even lower loss compared to regular wound cores, which require annealing.

[0008] This unicore generally has one or two joints. Patent Document 1 discloses an example with one joint in Figure 4 and an example with two joints in Figure 5.

[0009] Unicore, which has one joint, has better core characteristics than Unicore, which has two joints. However, when the joint is opened and part of the core (i.e., multiple electromagnetic steel sheets) is inserted into the coil, workability is poor due to back tension in the bent part, and a force acts in the direction of straightening the bent part, resulting in worse core characteristics than a normal wound core.

[0010] On the other hand, Unicore, which has two joints, has better assembly productivity than Unicore, which has one joint. However, because the condition of the Unicore butt joint has a significant effect on the core characteristics, it is important that the joint is securely made, but the butt joint is hidden by the transformer coil and cannot be confirmed.

[0011] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a transformer that improves the productivity of Unicore. [Means for solving the problem]

[0012] An example of a means for solving the above problem is as follows.

[0013] A transformer having a unicore, wherein the innermost block of the unicore has one butt joint at the yoke portion, and the outer butt joints of the innermost block are at two positions at the legs of the unicore. [Effects of the Invention]

[0014] By joining the innermost block at one point and using the yoke as the butt joint, the positioning accuracy of the subsequent two joints can be improved, which improves the productivity of Unicore transformers.

[0015] Further means and effects of the present invention will become apparent throughout the entire specification below. [Brief explanation of the drawings]

[0016] [Figure 1A] 1 is a structural example of a unicore of a single-phase transformer according to an embodiment of the present invention. [Figure 1B] FIG. 10 is an explanatory diagram of overlapping of electromagnetic steel sheets. [Figure 2A] FIG. 1 is a front view of a single-phase molded transformer according to an embodiment of the present invention. [Figure 2B] FIG. 1 is a side view of a single-phase molded transformer according to an embodiment of the present invention. [Figure 2C] FIG. 1 is a top view of a single-phase molded transformer according to an embodiment of the present invention. [Figure 3A] 1 is a structural example of a unicore of a three-phase transformer according to an embodiment of the present invention. [Figure 3B] FIG. 3B is an explanatory diagram of the outer core of FIG. 3A. [Figure 3C] FIG. 3B is an explanatory diagram of the inner core of FIG. 3A. [Figure 4] 1 shows an example of the structure of a wound core of a conventional single-phase transformer. [Figure 5] This is an example of the structure of a conventional single-phase Unicore with one joint. [Figure 6] This is an example of the structure of a conventional single-phase Unicore with two joints. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings as needed. [Example]

[0018] First, the single-phase molded transformer will be explained.

[0019] 2A is a front view, FIG. 2B is a side view, and FIG. 2C is a top view.

[0020] The single-phase molded transformer includes a unicore 1. It also includes high-voltage coils 2U and 2V and low-voltage coils 3U and 3V, with high-voltage side terminals 21U and 21V provided on high-voltage coils 2U and 2V, respectively. It also includes an upper metal fitting 4, a lower metal fitting 5, and low-voltage side terminals 22U, 22V, and 22O attached to the upper metal fitting 4.

[0021] FIG. 1A is a schematic cross-sectional view showing an example of the structure of a unicore of a single-phase transformer in one embodiment of the present invention.

[0022] This is a detailed diagram of coils 2U, 2V, 3U, and 3V in Unicore 1, as well as the spacer 6 between Unicore and the low-voltage coil.

[0023] 1A, in the Unicore 1 of the present invention, the innermost peripheral block 11 is joined at one point 101, and the outermost peripheral block 16 is joined at one point 102. The intermediate blocks 12U to 15U and 12L to 15L are joined at two points 103V and 104U.

[0024] In this application, the term "joint" is used to mean that the parts are close to each other but do not overlap. Therefore, at the joint, as shown in various places in Figure 1A, such as 101 and 102, there is a gap where the distance is 0 or more. Therefore, the term "butt joint" can also be used.

[0025] In addition, the short side in the figure is called the yoke part and the long side is called the leg part, which is a conventional designation in the field of transformers.

[0026] 1B is an explanatory diagram of the overlap of the electromagnetic steel sheets. In this embodiment, as an example, one wrap is made up of six electromagnetic steel sheets, and four wraps make up one block. 111 is the thickness of one electromagnetic steel sheet, 112 is the thickness of one wrap of Unicore, and 113 is the thickness of one block of Unicore.

[0027] Each joint is made up of magnetic steel sheets of the same layer separated by a gap 106, overlapping with the magnetic steel sheets of the next layer by an overlapping margin 105, and arranged in stages.

[0028] When manufacturing the transformer of this embodiment, coils 2U, 2V, 3U, and 3V are arranged horizontally in the position they will be in when the transformer is completed, with high-voltage terminals 21U and 21V on the bottom, and unicore 1 is inserted in order from the innermost block 11 to the outermost block 15, with the butt joints of coils 2U, 2V, 3U, and 3V open.

[0029] In this case, the innermost block 11 has a significant effect on the positioning accuracy of the two-point joint of the subsequent intermediate blocks. Block manufacturing accuracy can be higher with one-point joints than with two-point joints. On the other hand, two-point joints have the advantage of being easier to manufacture because they are constructed using two U-shaped intermediate blocks during the manufacturing process.

[0030] Therefore, as shown in Figure 1A, it is desirable to use a combined structure and manufacturing method in which the innermost block is made with a single joint and the intermediate block is made with a two-joint structure and two-joint structure. This allows the innermost block to be made with high precision using a single joint, which also improves the precision of the subsequent intermediate block, which is made with two joints. Furthermore, productivity can be improved compared to when the intermediate block is made with a single joint.

[0031] On the other hand, it is desirable to use a single joint for the outermost block 16. This is because, if the joint is located at the yoke, the outermost joint is visible from the outside, as shown by 102 in Figure 1A. This has the advantage of facilitating quality control, since even if the hidden inner intermediate layer has a two-layer joint structure, the joint condition can be inferred and the manufacturing precision of the Unicore or the transformer can be inferred. If the manufacturing precision of the two-layer joint of the intermediate layer is poor, a large gap will also be created in 102, so the dimensions of 102 can be used to infer the manufacturing precision of 103V and 103U. Furthermore, this avoids the need to position the joint at the leg of the outermost block. In other words, there is no discontinuity in the outermost block at the leg, which also functions to protect the outermost butt joint of the intermediate block when inserting the spacer 6 between the low-voltage coils 3U and 3V and the Unicore 1.

[0032] Therefore, in order to encompass all of these advantages, it would be most desirable to have the innermost block be structured with a single joint, the intermediate block be structured with two joints, and the outermost block be structured with a single joint, in the sense that this would allow the effects of both to be achieved.

[0033] 1A, as an example, butt joints 101 and 102 are located in the center of the yoke, and butt joints 103U and 103V are arranged diagonally in four blocks. However, these positions can be arranged in various patterns depending on the balance between leg length, yoke length, stacking thickness, and characteristics, and are not limited to the structure disclosed in FIG. 1A.

[0034] 4 to 6 show conventional structures as comparative examples.

[0035] Figure 4 shows an example of the structure of a wound core for a conventional single-phase transformer as a comparative example. The core legs where the coil is placed have no butt joints, but there is only one butt joint, but the R section requires stress relief annealing. Note that the corners are R, and Figure 4 is not a Unicore.

[0036] Figure 5 shows an example of the structure of a conventional single-phase Unicore with a single joint, as a comparative example. A typical Unicore with a single joint has no butt joint at the core legs where the coil is placed, as with a normal wound core, and has only one butt joint. Although stress relief annealing is not required, when inserting each Unicore block into the coil, the bent portions of each Unicore block temporarily deform in a straightened direction, resulting in a deterioration in characteristics, and the springback of the bent portions makes it difficult to insert the core into the coil.

[0037] Figure 6 shows an example of the structure of a conventional single-phase unicore with two joints as a comparative example. In a normal unicore with two joints, the butt joint is located on the core leg where the coil is located. In the case of a normal unicore with two joints, the joint is hidden by the coil and cannot be seen, making it impossible to check whether the required overlap 105 and gap 106 are satisfied, whether the joint is uneven, etc.

[0038] As described above, the unicore of the present invention disclosed in FIG. 1A as an example, and the transformer using the unicore, can achieve improved productivity and accuracy compared to the structures shown as comparative examples in FIGS. 4 and 5. [Example]

[0039] 3A shows a structural example when the technical concept of the first embodiment is applied to a unicore of a three-phase transformer, which has a three-phase three-leg core structure.

[0040] The three-phase, three-legged core structure Unicore consists of two inner cores 7 and one outer core 8. As shown in Figure 3C, the inner core 7 has the same configuration as the single-phase Unicore in Figure 1. As shown in Figure 3B, the outer core 8 also has the same configuration as the single-phase Unicore in Figure 1, although it is longer horizontally.

[0041] In this embodiment, butt joints 701, 702, 801, and 802 shown in FIG. 3A are located in the center of the yoke, and butt joints 703U, 703V, 803U, and 803V are divided into four blocks and arranged diagonally, but various patterns can be considered for this position depending on the balance between leg length, stacking thickness, and characteristics.

[0042] In this embodiment, the same effects as in the first embodiment can be achieved.

[0043] The above examples illustrate the ideas and concepts of the present invention. Of course, the scope of the present invention also includes examples that are realized by combining the examples. Furthermore, as long as the disclosed ideas and concepts are used, any modifications or similar examples are also included within the scope of the present invention.

[0044] Furthermore, one example of the present invention described using the above embodiments can also be expressed as follows.

[0045] <Part 1> A transformer having a unicore, wherein the innermost block of the unicore has one butt joint at the yoke portion, and the outer butt joints of the innermost block are at two positions at the legs of the unicore.

[0046] <Part 2> A transformer having a unicore, wherein the outermost block of the unicore has one butt joint at the yoke portion, and the inner butt joint of the outermost block has two butt joints at the legs of the unicore.

[0047] <Part 3> <1> The transformer according to the present invention, wherein the outermost block of the unicore is butted at a single yoke portion.

[0048] <Part 4> <2> The transformer according to the above item 2, wherein the butt joint of the innermost peripheral block of the unicore is at one yoke portion.

[0049] <Part 5> A transformer according to <No. 3> or <No. 4>, wherein one of the butt joints of the innermost block and the outermost block is arranged above the yoke portion and the other is arranged below the yoke portion.

[0050] <Part 6> The transformer according to any one of <Item 1> to <Item 4>, wherein the transformer is a three-phase transformer having two inner cores and one outer core.

[0051] <Part 7> <5> The transformer according to the present invention, wherein the transformer is a three-phase transformer having two inner cores and one outer core.

[0052] <Part 8> <No. 6> A transformer in which the two inner cores and one outer core each have one butt joint between the innermost block and the outermost block at a yoke portion, and two butt joints at legs of other blocks.

[0053] <No. 9> <7> A transformer according to the present invention, wherein the two inner cores and one outer core each have one butt joint between the innermost block and the outermost block at a yoke portion, and two butt joints at legs of the other blocks.

[0054] <Part 10> A unicore for a transformer, in which the innermost block of the unicore is butted at one yoke portion, and the block outside the innermost block is butted at two leg portions.

[0055] <Part 11> A unicore for a transformer, in which the outermost block of the unicore has one butt joint at the yoke portion, and the block inside the outermost block has two butt joints at the leg portions.

[0056] <Part 12> <Item 10> The Unicore described in <Item 10>, wherein the abutting portion of the outermost block of the Unicore is a single yoke portion.

[0057] <Part 13> <Item 11> The Unicore described in <Item 11>, wherein the abutting portion of the innermost peripheral block of the Unicore is a single yoke portion.

[0058] <Part 14> In the Unicore described in <No. 12> or <No. 13>, one of the butt joints of the innermost block and the outermost block is arranged above the yoke portion and the other is arranged below the yoke portion.

[0059] <Part 15> <No. 10> A transformer in which the Unicore according to any one of claims 10 to 13 is mounted is a three-phase transformer having two inner cores and one outer core.

[0060] <Part 16> The transformer in which the Unicore described in <No. 14> is mounted is a three-phase transformer having two inner cores and one outer core.

[0061] <Part 17> In the Unicore described in <No. 15>, the two inner cores and one outer core have one butt joint between the innermost block and the outermost block at the yoke section, and two at the legs of the other blocks.

[0062] <Part 18> In the Unicore described in <No. 16>, the two inner cores and one outer core have one butt joint between the innermost block and the outermost block at the yoke section, and two at the legs of the other blocks. [Explanation of symbols]

[0063] 1: Single-phase Unicore 2U: U-phase high voltage coil 2V: V-phase high voltage coil 3U: u-phase low voltage coil 3V: v-phase low voltage coil 4: Upper bracket 5: Lower bracket 6: Unicore-low voltage coil spacer 7: Three-phase tripod unicore inner core 8: Three-phase tripod unicore outer core 9: Conventional single-phase wound core 11: Innermost block of single-phase Unicore 12U: Second upper block from the inside of the single-phase Unicore 12L: Second lower block from the inside of the single-phase Unicore 13U: The third upper block from the inside of the single-phase Unicore 13L: The third lower block from the inside of the single-phase Unicore 14U: The fourth upper block from the inside of the single-phase Unicore 14L: The fourth lower block from the inside of the single-phase Unicore 15U: The fifth upper block from the inside of the single-phase Unicore 15L: The fifth lower block from the inside of the single-phase Unicore 16: Outermost block of single-phase Unicore 21U: High voltage side U terminal 21V: High voltage side V terminal 22U: Low voltage side u terminal 22V: Low voltage side V terminal 22O: Low voltage side terminal 71: Innermost block of three-phase three-legged Unicore core 72U: Second upper block from the inside of the three-phase tripod Unicore core 72L: Three-phase tripod Unicore inner core Second lower block from the inside of the Unicore 73U: Three-phase tripod unicore inner core, third upper block from the inside of the unicore 73L: Three-phase tripod unicore inner core, third lower block from the inside of the unicore 74U: Three-phase tripod unicore inner core, fourth upper block from the inside of the unicore 74L: Fourth lower block from the inside of the three-phase tripod Unicore inner core 75U: Three-phase tripod unicore inner core, fifth upper block from the inside of the unicore 75L: Three-phase tripod Unicore inner core, fifth lower block from the inside of the Unicore 76: Three-phase tripod unicore inner core unicore outermost block 701: Three-phase three-legged unicore inner core, butt joint of the innermost block of the unicore 702: Three-phase three-legged unicore inner core, butt joint of the outermost block of the unicore 703U: Three-phase three-legged unicore inner core, unicore intermediate block U-leg butt joint 703V: Three-phase three-legged unicore inner core, unicore intermediate block V-leg butt joint 81: Innermost block of three-phase tripod unicore outer core 82U: Second upper block from the inside of the three-phase tripod unicore outer core 82L: Three-phase tripod Unicore outer core, second lower block from the inside of the Unicore 83U: Three-phase tripod unicore outer core, third upper block from the inside of the unicore 83L: Three-phase tripod unicore outer core, third lower block from the inside of the unicore 84U: Three-phase tripod unicore outer core, fourth upper block from the inside of the unicore 84L: Fourth lower block from the inside of the three-phase tripod Unicore outer core Unicore 85U: Three-phase tripod unicore outer core, fifth upper block from the inside of the unicore 85L: Three-phase tripod Unicore outer core, fifth lower block from the inside of the Unicore 86: Three-phase tripod Unicore outer core Unicore outermost block 91U: Conventional single-phase unicore with one joint 92U: Conventional single-phase unicore with two joints 101: Joint of the innermost block of the single-phase Unicore 102: Abutment of outermost block of single-phase Unicore 103U: U-leg butt joint of the intermediate block of the single-phase Unicore 103V: Single-phase Unicore intermediate block V-leg butt joint 105: Overlap of the joint of the Unicore 106: Gap at the joint of Unicore 111: Thickness of one electromagnetic steel sheet 112: Thickness of one wrap of Unicore 113: The thickness of one block of Unicorn 801: Three-phase tripod unicore outer core unicore innermost block butt joint 802: Three-phase tripod unicore outer core, butt joint of the outermost block of the unicore 803U: Three-phase three-legged unicore outer core unicore intermediate block U-leg butt joint 803V: Three-phase three-legged unicore outer core unicore intermediate block V-leg butt joint 901: Butt joint of conventional single-phase wound core 901U: Conventional single-phase unicore butt joint 902U: Conventional two-point joint for single-phase Unicore

Claims

1. A transformer having a unicore, wherein the innermost block of the unicore has one butt joint at a yoke portion, and the outer butt joints of the innermost block are two at the legs of the unicore.

2. A transformer having a unicore, wherein the outermost block of the unicore has one butt joint at a yoke portion, and the innermost block of the unicore has two butt joints at legs of the unicore.

3. 2. A transformer according to claim 1, wherein the outermost block of said unicore is butted at one yoke portion.

4. 3. A transformer according to claim 2, wherein the innermost peripheral block of said unicore is butted at one yoke portion.

5. 5. A transformer according to claim 3 or claim 4, wherein one of the butt joints of the innermost block and the outermost block is arranged above the yoke portion and the other is arranged below the yoke portion.

6. 5. The transformer according to claim 1, wherein the transformer is a three-phase transformer having two inner cores and one outer core.

7. 6. The transformer of claim 5, wherein the transformer is a three-phase transformer having two inner cores and one outer core.

8. 7. A transformer according to claim 6, wherein the two inner cores and one outer core each have one butt joint between the innermost block and the outermost block at a yoke portion, and two butt joints between the other blocks at legs.

9. 8. A transformer according to claim 7, wherein the two inner cores and one outer core each have one butt joint between the innermost block and the outermost block at a yoke portion, and two butt joints between the other blocks at legs.

10. A unicore for a transformer, wherein the innermost peripheral block of the unicore is joined to one yoke portion, and the outer block of the innermost peripheral block is joined to two leg portions.

11. A unicore for a transformer, wherein the outermost block of the unicore is butted at one yoke portion, and the block inside the outermost block is butted at two leg portions.

12. 11. The unicore according to claim 10, wherein the outermost block of the unicore is butted at one yoke portion.

13. 12. The unicore according to claim 11, wherein the abutting portion of the innermost peripheral block of the unicore is a single yoke portion.

14. 14. The unicore according to claim 12 or 13, wherein one of the abutting portions of the innermost peripheral block and the outermost peripheral block is disposed above the yoke portion and the other is disposed below the yoke portion.

15. A transformer in which the Unicore according to any one of claims 10 to 13 is mounted is a three-phase transformer having two inner cores and one outer core.

16. The Unicore according to claim 14, wherein the transformer in which the Unicore is mounted is a three-phase transformer having two inner cores and one outer core.

17. 16. The Unicore of claim 15, wherein the two inner cores and one outer core have one butt joint between the innermost block and the outermost block at a yoke portion, and two butt joints at legs of the other blocks.

18. 17. The Unicore of claim 16, wherein the two inner cores and one outer core have one butt joint between the innermost block and the outermost block at a yoke portion, and two butt joints between the other blocks at legs.

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