Improved foil coil structure

Abstract

The utility model relates to the technical field of coil structures, in particular to an improved foil coil structure which comprises an iron core column. An upper winding and a lower winding are wound on the iron core column; the upper winding is formed by winding an upper coil foil tape and upper interlayer insulation paper which are attached to each other along the top of the iron core column; the lower winding is formed by winding a lower coil foil tape and lower interlayer insulation paper which are attached to each other along the bottom of the iron core column; the upper coil foil tape and the lower coil foil tape are connected in series, and the sum of the number of turns of the upper coil foil tape and the number of turns of the lower coil foil tape which are connected in series is the total number of turns of the improved foil coil structure; the thickness of the upper coil foil tape is the same as that of the lower coil foil tape; and the width of the upper coil foil tape is greater than that of the lower coil foil tape. According to the utility model, the width of the upper coil foil tape is larger than that of the lower coil foil tape, so that the temperature of the upper winding can be reduced, the temperature rise of the upper winding and the temperature rise of the lower winding are basically close, the hot-spot temperature rise of the coil is reduced, and the product reliability is improved.

Description

Technical Field

[0001] This utility model relates to the field of coil structure technology, specifically to an improved foil-wound coil structure. Background Technology

[0002] In today's fiercely competitive transformer industry, small size, high power density, and low cost have become key objectives pursued by many transformer manufacturers and end-user customers in new product development. In striving towards this goal, improving the temperature resistance rating of products has become an effective technical approach. As the allowable temperature rise of products gradually increases, transformers can be further reduced in physical size, while the amount of materials used can also be reduced accordingly. This not only aligns with the trend of miniaturization and lightweighting in modern electronic products but also effectively reduces production costs and enhances the product's market competitiveness.

[0003] However, in practice, a significant bottleneck has gradually emerged. Generally, the temperature resistance rating of insulation materials is positively correlated with their unit price; that is, the higher the temperature resistance, the higher the unit price. This makes cost control a major challenge while pursuing high temperature resistance ratings to achieve product miniaturization. Therefore, exploring how to reduce the amount of insulation material used, while ensuring that the overall performance is not affected, has become one of the important research directions for reducing product costs.

[0004] Currently, several technologies have been attempted to address this issue. For example, Chinese utility model patent application number 2024103286983 employs a method of halving the width of the foil strip, doubling its thickness, and using a two-turn winding method to achieve the goal of halving the insulation layer. This approach successfully reduces the amount of insulating paper used without altering the overall size and performance of the device, thus lowering costs to some extent. However, this technology is not without its flaws. In practical applications, it has been found that when the coil is divided into upper and lower sections, and the width of the upper foil strip is the same as that of the lower foil strip, the temperature rise of the upper coil is significantly higher than that of the lower coil. This phenomenon indicates that the existing design of equal width between the upper and lower coil foil strips is not the optimal solution, and there is still room for further optimization. Utility Model Content

[0005] The purpose of this invention is to address the aforementioned shortcomings in the prior art by providing an improved foil-wound coil structure.

[0006] The objective of this utility model is achieved through the following technical solution: an improved foil-wound coil structure, comprising an iron core column; the iron core column is wound with an upper winding and a lower winding; the upper winding is formed by winding an upper coil foil strip and an upper interlayer insulating paper together along the top of the iron core column; the lower winding is formed by winding a lower coil foil strip and a lower interlayer insulating paper together along the bottom of the iron core column.

[0007] The upper coil foil strip and the lower coil foil strip are connected in series, and the sum of the number of turns of the upper coil foil strip and the number of turns of the lower coil foil strip is the total number of turns of the improved foil-wound coil structure.

[0008] The thickness of the upper coil foil strip is the same as the thickness of the lower coil foil strip; the width of the upper coil foil strip is greater than the width of the lower coil foil strip.

[0009] The present invention is further provided that a ventilation gap is provided between the upper winding and the lower winding.

[0010] The present invention is further configured such that the upper winding is provided with an upper air duct; and the lower winding is provided with a lower air duct.

[0011] The present invention is further configured such that the width of the upper interlayer insulating paper is greater than the width of the upper coil foil strip; and the width of the lower interlayer insulating paper is greater than the width of the lower coil foil strip.

[0012] The present invention is further configured such that an upper cable inlet is provided on the inner side of the front end of the top of the iron core column; and a lower cable inlet is provided on the inner side of the front end of the bottom of the iron core column.

[0013] The outer front end of the top of the iron core column is provided with an upper lead-out row; the upper lead-out row passes through the lower winding and extends to the bottom of the iron core column; the outer front end of the bottom of the iron core column is provided with a lower lead-out row; the lower lead-out row passes through the upper winding and extends to the top of the iron core column.

[0014] The upper outgoing cable and the lower incoming cable are connected in series;

[0015] The upper coil foil strip is located between the upper inlet and the upper outlet wires, and is welded to the upper inlet and the upper outlet wires respectively before being led out; the lower coil foil strip is located between the lower inlet and the lower outlet wires, and is welded to the lower inlet and the lower outlet wires respectively before being led out.

[0016] The present invention is further provided that the bottom of the upper cable outlet and the top of the lower cable outlet are both covered with insulating tape.

[0017] The present invention is further configured such that the bottom of the upper cable outlet and the top of the lower cable outlet are both covered with insulating paper pads.

[0018] The present invention is further configured such that the core column includes a first core column, a second core column, and a third core column; the first core column, the second core column, and the third core column are each provided with an upper winding and a lower winding;

[0019] An upper horizontal iron is provided between the top of the first core column, the top of the second core column, and the top of the third core column; a lower horizontal iron is provided between the bottom of the first core column, the bottom of the second core column, and the bottom of the third core column.

[0020] A manufacturing method for producing an improved foil-wound coil structure includes the following steps:

[0021] S1. Attach the upper coil foil strip to the upper interlayer insulating paper, and attach the lower coil foil strip to the lower interlayer insulating paper;

[0022] S2. Simultaneously, the upper coil foil strip and the upper interlayer insulation paper are wound along the top of the iron core column, and the lower coil foil strip and the lower interlayer insulation paper are wound along the bottom of the iron core column.

[0023] S3. Connect the end of the upper coil foil strip to the beginning of the lower coil foil strip in series.

[0024] The present invention is further configured such that the selection of the width of the upper coil foil and the width of the lower coil foil include the following steps:

[0025] A1. Measure the height of the top surface of the lower coil foil and the top surface of the upper coil foil.

[0026] A2. After applying current, measure the temperature rise of the upper winding and the temperature rise of the lower winding;

[0027] A3. Calculate the unit heat load of the upper coil foil and the unit heat load of the lower coil foil according to the formula T=k1*(H / 1000)^0.2*q^0.8; where T is the temperature rise, k1 is the temperature rise coefficient, H is the height of the top surface of the coil foil, and q is the unit heat load.

[0028] A4. Calculate the width of the upper coil foil and the width of the lower coil foil based on the unit heat load of the upper coil foil and the unit heat load of the lower coil foil.

[0029] The beneficial effects of this utility model are as follows: By making the width of the upper coil foil strip greater than that of the lower coil foil strip, this utility model can reduce the temperature of the upper winding, making the temperature rise of the upper winding and the lower winding basically similar, reducing the temperature rise of the hot spot of the coil, and improving the reliability of the product. Attached Figure Description

[0030] The utility model will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present utility model. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0031] Figure 1 This is a perspective view of the present invention;

[0032] Figure 2 This is a top view of the present invention;

[0033] Figure 3This is a schematic diagram of the structure of the three iron core columns combined according to this utility model;

[0034] Figure 4 This is a structural schematic diagram of the three iron core columns of this utility model from another perspective;

[0035] Figure 5 This is a table showing the selection of the width of the upper coil foil and the width of the lower coil foil of this utility model;

[0036] The components are: 1. Core post; 2. Upper winding; 21. Upper coil foil strip; 22. Upper interlayer insulating paper; 3. Lower winding; 31. Lower coil foil strip; 32. Lower interlayer insulating paper; 4. Ventilation gap; 51. Upper air duct; 52. Lower air duct; 61. Upper inlet cable; 62. Upper outlet cable; 71. Lower inlet cable; 72. Lower outlet cable; 81. Insulating tape; 82. Insulating paper pad; 91. First core post; 92. Second core post; 93. Third core post; 94. Upper crossbar; 95. Lower crossbar. Detailed Implementation

[0037] The present invention will be further described in conjunction with the following embodiments.

[0038] Depend on Figures 1 to 5 As can be seen, the improved foil-wound coil structure described in this embodiment includes an iron core column 1; the iron core column 1 is wound with an upper winding 2 and a lower winding 3; the upper winding 2 is formed by winding an upper coil foil strip 21 and an upper interlayer insulating paper 22 together along the top of the iron core column 1; the lower winding 3 is formed by winding a lower coil foil strip 31 and a lower interlayer insulating paper 32 together along the bottom of the iron core column 1.

[0039] The upper coil foil strip 21 and the lower coil foil strip 31 are connected in series. The sum of the number of turns of the upper coil foil strip 21 and the number of turns of the lower coil foil strip 31 after being connected in series is the total number of turns of the improved foil-wound coil structure.

[0040] The thickness of the upper coil foil strip 21 is the same as the thickness of the lower coil foil strip 31; the width of the upper coil foil strip 21 is greater than the width of the lower coil foil strip 31.

[0041] Specifically, in the improved foil-wound coil structure described in this embodiment, the upper winding 2 can be wound together with the lower winding 3 during manufacturing, which can effectively improve the overall production efficiency. In addition, by making the width of the upper coil foil strip 21 greater than the width of the lower coil foil strip 31, the temperature of the upper winding 2 can be reduced, making the temperature rise of the upper winding 2 and the lower winding 3 basically similar, reducing the hot spot temperature rise of the coil and improving product reliability.

[0042] In this embodiment, an improved foil-wound coil structure is provided, with a ventilation gap 4 between the upper winding 2 and the lower winding 3. This design improves the overall heat dissipation function.

[0043] The improved foil-wound coil structure described in this embodiment includes an upper air duct 51 for the upper winding 2 and a lower air duct 52 for the lower winding 3. This configuration improves the overall heat dissipation function.

[0044] In this embodiment, an improved foil-wound coil structure is described, wherein the width of the upper interlayer insulating paper 22 is greater than the width of the upper coil foil strip 21; and the width of the lower interlayer insulating paper 32 is greater than the width of the lower coil foil strip 31. This arrangement ensures that the upper and lower edges of the upper interlayer insulating paper 22 extend beyond the upper and lower edges of the upper coil foil strip 21, and that the upper and lower edges of the lower interlayer insulating paper 32 extend beyond the lower coil foil strip 31, thereby effectively providing insulation.

[0045] This embodiment describes an improved foil-wound coil structure, wherein an upper inlet wire row 61 is provided on the inner side of the front end of the top of the iron core column 1; a lower inlet wire row 71 is provided on the inner side of the front end of the bottom of the iron core column 1; an upper outlet wire row 62 is provided on the outer side of the front end of the top of the iron core column 1; the upper outlet wire row 62 passes through the lower winding 3 and extends to the bottom of the iron core column 1; a lower outlet wire row 72 is provided on the outer side of the front end of the bottom of the iron core column 1; the lower outlet wire row 72 passes through the upper winding 2 and extends to the top of the iron core column 1; the upper outlet wire row 62 and the lower inlet wire row 71 are connected in series; an upper coil foil strip 21 is disposed between the upper inlet wire row 61 and the upper outlet wire row 62, and is welded to the upper inlet wire row 61 and the upper outlet wire row 62 respectively before being led out; a lower coil foil strip 31 is disposed between the lower inlet wire row 71 and the lower outlet wire row 72, and is welded to the lower inlet wire row 71 and the lower outlet wire row 72 respectively before being led out.

[0046] Specifically, through the above arrangement, after the upper winding 2 and the lower winding 3 are wound simultaneously, they are connected at the upper output line 62 and the lower input line 71, so that the end of the upper winding 2 and the beginning of the lower winding 3 are connected in series.

[0047] In this embodiment, an improved foil-wound coil structure is described, in which the bottom of the upper lead-out bar 62 and the top of the lower lead-out bar 72 are both covered with insulating tape 81. This arrangement facilitates insulation between the upper lead-out bar 62 and the lower winding 3, and between the lower lead-out bar 72 and the upper winding 2.

[0048] In this embodiment, an improved foil-wound coil structure is described, in which the bottom of the upper lead-out bar 62 and the top of the lower lead-out bar 72 are both covered with insulating paper pads 82. This arrangement improves the insulation performance between the upper lead-out bar 62 and the lower winding 3, as well as the insulation performance between the lower lead-out bar 72 and the upper winding 2.

[0049] The improved foil-wound coil structure described in this embodiment includes a first core post 91, a second core post 92, and a third core post 93. Each of the first core post 91, the second core post 92, and the third core post 93 is provided with an upper winding 2 and a lower winding 3. An upper horizontal iron 94 is provided between the top of the first core post 91, the top of the second core post 92, and the top of the third core post 93. A lower horizontal iron 95 is provided between the bottom of the first core post 91, the bottom of the second core post 92, and the bottom of the third core post 93.

[0050] Specifically, through the above-described configuration, this embodiment allows for the additional windings 2 and 3 to be wound around the first core post 91, the second core post 92, and the third core post 93, respectively, thereby forming a three-phase transformer.

[0051] The manufacturing method for producing an improved foil-wound coil structure described in this embodiment includes the following steps:

[0052] S1. The upper coil foil strip 21 is bonded together with the upper interlayer insulating paper 22, and the lower coil foil strip 31 is bonded together with the lower interlayer insulating paper 32;

[0053] S2. Simultaneously, the upper coil foil strip 21 and the upper interlayer insulating paper 22 are wound along the top of the iron core column 1, and the lower coil foil strip 31 and the lower interlayer insulating paper 32 are wound along the bottom of the iron core column 1.

[0054] S3. Connect the end of the upper coil foil strip 21 in series with the beginning of the lower coil foil strip 31.

[0055] Specifically, the manufacturing method for the improved foil-wound coil structure described in this embodiment divides the total number of turns of the improved foil-wound coil structure into upper and lower parts for winding. Each part is wound in half and then connected in series, reducing the number of turns to half of the original, which effectively improves production efficiency. At the same time, since the number of coil winding layers is halved, the total amount of upper interlayer insulation paper 22 and lower interlayer insulation paper 32 is also reduced to half of the original, reducing material costs.

[0056] The manufacturing method for an improved foil-wound coil structure described in this embodiment includes the following steps for selecting the width of the upper coil foil strip 21 and the width of the lower coil foil strip 31:

[0057] A1. Measure the height of the top surface of the lower coil foil strip 31 and the height of the top surface of the upper coil foil strip 21;

[0058] A2. After applying current, measure the temperature rise of the upper winding 2 and the lower winding 3;

[0059] A3. Calculate the unit heat load of the upper coil foil 21 and the unit heat load of the lower coil foil 31 according to the formula T=k1*(H / 1000)^0.2*q^0.8; where T is the temperature rise, k1 is the temperature rise coefficient, H is the height of the top surface of the coil foil, and q is the unit heat load.

[0060] A4. Calculate the width of the upper coil foil strip 21 and the width of the lower coil foil strip 31 based on the unit heat load of the upper coil foil strip 21 and the unit heat load of the lower coil foil strip 31.

[0061] To illustrate this more clearly, here is an example:

[0062] 1. Traditional products have windings consisting of a single foil strip wound with interlayer insulating paper:

[0063] 1) The foil strip is 0.6mm thick * 400mm wide / 50 turns, weighing 60kg;

[0064] 2) The interlayer insulation paper uses a thickness of 0.14mm * width of 420mm / 50 turns and a weight of 6.5kg;

[0065] 3) Calculate the temperature rise. The coil height H = 0.4m, the unit heat load q = 0.11 * 10^4 W / m^2, the coefficient k1 = 0.432, and the coil temperature rise To = 0.432 * 0.4^0.2 * (0.11 * 10^4)^0.8 = 97.5K.

[0066] 2. Product with patent number 2024103286983:

[0067] Since the coils are placed vertically, the foil strips for both coils have the same thickness and width. The foil strip thickness is twice that of traditional products: 0.6 * 2 = 1.2 mm, and the width is half that of traditional products: 400 / 2 = 200 mm. Keeping the current density of the winding constant, in this way:

[0068] 1) The foil tape uses a thickness of 1.2mm * 200mm width / (25 upper turns + 25 lower turns) of approximately 60kg. The total weight remains basically unchanged. Here, the upper winding foil tape is 200mm wide and the lower winding foil tape is 200mm wide.

[0069] 2) The interlayer insulation paper uses a thickness of 0.14mm * width of 215mm (25 turns on top + 25 turns on bottom) / 3.26kg. Here, the width of the upper interlayer insulation paper is 215mm and the width of the lower interlayer insulation paper are both 215mm. Compared with the traditional product, the amount of interlayer insulation paper used is reduced by about half of 6.5kg, saving material costs.

[0070] 3) Temperature rise calculation: When the foil strip is evenly bisected, the height H of the top surface of the lower foil strip is 200mm, the distance D between the top surface of the lower foil strip and the bottom surface of the upper foil strip is 20mm, and the height H of the top surface of the upper coil is 200+20+200=420mm. Since the winding current density and the air duct placement remain unchanged, the unit heat load q value is still 0.11*10^4W / m^2. The air duct and the outer perimeter of the coil remain unchanged. At this time,

[0071] The temperature rise of the lower winding, T_lower, is calculated as follows: T_lower = 0.432 * 0.2 * (0.11 * 10^4) * 0.8 = 85 K.

[0072] The temperature rise of the upper winding, Tupper, is calculated as follows: Tupper = 0.432 * 0.42^0.2 * (0.11 * 104)^0.8 = 98.5 K.

[0073] As can be seen from the above, the product with patent number 2024103286983 does save on insulating paper, but the temperature rise of the upper and lower coils differs by 13.5K.

[0074] 3. The product in this embodiment:

[0075] Similarly, since the coils are placed vertically, with a total foil width of 400mm, the upper coil foil strip 21 is 220mm wide, and the lower coil foil strip 31 is 180mm wide. Therefore, the height of the top surface of the lower coil foil strip 31 is H1 = 180mm, the distance between the top surface of the lower coil foil strip 31 and the bottom surface of the upper coil foil strip 21 is D1 = 20mm, and the height of the top surface of the upper coil foil strip 21 is H2 = 180 + D20 + 220 = 420mm. The thickness of the upper coil foil strip 21 and the lower coil foil strip 31 is twice that of the traditional product, 0.6 * 2 = 1.2mm. The width of the upper coil insulation paper is 235mm, and the width of the lower coil insulation paper is 195mm. Since the total width of the foil strips and the total width of the interlayer insulation paper are the same as those of the product in patent number 2024103286983, the amount used is also the same.

[0076] 1) The sum of the upper and lower coil foil strips 31 remains 60kg, so the total weight is basically unchanged. Here, the upper coil foil strip 21 is 220mm wide, and the lower coil foil strip 31 is 180mm wide;

[0077] 2) The sum of the upper and lower interlayer insulation paper 32 remains 3.26kg. Here, the upper interlayer insulation paper 22 is 235mm wide, and the lower interlayer insulation paper 32 is 195mm wide. Compared with the traditional product's 6.5kg interlayer insulation paper usage, it is reduced by about half.

[0078] 3) Temperature rise calculation: When the width of the coil foil strip is 31 and 180, the air passage and the outer perimeter of the coil remain unchanged. At this time, the current density increases and the unit heat load increases.

[0079] Under unit heat load q = 0.11 / 180*200 = 0.1222*10^4 W / m^2

[0080] The temperature rise of the lower winding 3, T_lower, is calculated as follows: T_lower = 0.432 * 0.18^0.2 * (0.1222 * 10^4)^0.8 = 90.3 K.

[0081] When the width of the upper coil foil strip is 220, the air passage remains unchanged, the outer circumference of the coil remains unchanged, and the current density decreases, and the unit heat load decreases.

[0082] The unit heat load qup = 0.11 / 220 * 200 = 0.1 * 104 W / m2

[0083] The temperature rise of the upper winding 2, Tupper, is calculated as follows: Tupper = 0.432 * 0.42^0.2 * (0.1 * 104)^0.8 = 91.2 K.

[0084] As can be seen from the calculations above, compared with the product of patent number 2024103286983, the maximum temperature rise of this utility model is reduced by approximately 98.5-91.2=7.3K; compared with the traditional product, the temperature rise is reduced by approximately 97.5-91.2=6.3K. As can be seen from the above example, this utility model not only saves insulating paper, but also reduces the temperature rise of the coil hot spot.

[0085] It's easy to understand that the taller the coil, the longer the internal airflow duct, and the greater the obstruction to airflow. Therefore, taller coils exhibit more uneven temperature distribution, resulting in a higher temperature at the top and a lower temperature at the bottom. This invention, by segmenting the coil and appropriately adjusting the foil width ratio of the upper and lower windings 3, and incorporating the height data affecting coil temperature rise into the calculations, yields an optimal foil width combination for the upper and lower windings 3. Figure 5 As shown, the coil hot spot temperature rise is reduced without increasing the amount of foil tape used. In fact, the presence of the spacing D1 in the middle of the coil is more conducive to heat dissipation. In terms of cost, the cost of insulation paper is also halved because the number of winding turns is halved, which reduces the amount of insulation paper used. In terms of labor time, only half the number of turns needs to be wound, which is also reduced to about 50% of the previous time. In terms of size, because the number of insulation paper layers is halved, the coil thickness is smaller and the power density of the product is higher. The foil tape mentioned in this utility model mainly refers to conductors with low resistivity such as copper foil and aluminum foil.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit the scope of protection of this utility model. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the essence and scope of the technical solutions of this utility model.

Claims

1. An improved foil-wound coil structure, characterized in that: It includes an iron core column (1); the iron core column (1) is wound with an upper winding (2) and a lower winding (3); the upper winding (2) is formed by winding an upper coil foil strip (21) and an upper interlayer insulating paper (22) together along the top of the iron core column (1); the lower winding (3) is formed by winding a lower coil foil strip (31) and a lower interlayer insulating paper (32) together along the bottom of the iron core column (1); The upper coil foil strip (21) and the lower coil foil strip (31) are connected in series. The sum of the number of turns of the upper coil foil strip (21) and the number of turns of the lower coil foil strip (31) is the total number of turns of the improved foil-wound coil structure. The thickness of the upper coil foil strip (21) is the same as the thickness of the lower coil foil strip (31); the width of the upper coil foil strip (21) is greater than the width of the lower coil foil strip (31).

2. The improved foil-wound coil structure according to claim 1, characterized in that: A ventilation gap (4) is provided between the upper winding (2) and the lower winding (3).

3. The improved foil-wound coil structure according to claim 1, characterized in that: The upper winding (2) is provided with an upper air duct (51); the lower winding (3) is provided with a lower air duct (52).

4. The improved foil-wound coil structure according to claim 1, characterized in that: The width of the upper interlayer insulating paper (22) is greater than the width of the upper coil foil strip (21); the width of the lower interlayer insulating paper (32) is greater than the width of the lower coil foil strip (31).

5. The improved foil-wound coil structure according to claim 1, characterized in that: The top of the iron core column (1) has an upper inlet bar (61) on the inner side of the front end; the bottom of the iron core column (1) has a lower inlet bar (71) on the inner side of the front end. The top of the iron core column (1) has an upper lead-out bar (62) on the outer side of the front end; the upper lead-out bar (62) passes through the lower winding (3) and extends to the bottom of the iron core column (1); the bottom of the iron core column (1) has a lower lead-out bar (72) on the outer side of the front end of the bottom; the lower lead-out bar (72) passes through the upper winding (2) and extends to the top of the iron core column (1); The upper outgoing line (62) and the lower incoming line (71) are connected in series; The upper coil foil strip (21) is located between the upper inlet wire row (61) and the upper outlet wire row (62), and is led out after being welded to the upper inlet wire row (61) and the upper outlet wire row (62) respectively; the lower coil foil strip (31) is located between the lower inlet wire row (71) and the lower outlet wire row (72), and is led out after being welded to the lower inlet wire row (71) and the lower outlet wire row (72) respectively.

6. The improved foil-wound coil structure according to claim 5, characterized in that: The bottom of the upper cable outlet (62) and the top of the lower cable outlet (72) are both covered with insulating tape (81).

7. An improved foil-wound coil structure according to claim 5, characterized in that: The bottom of the upper cable outlet (62) and the top of the lower cable outlet (72) are both covered with insulating paper pads (82).

8. The improved foil-wound coil structure according to claim 1, characterized in that: The core column (1) includes a first core column (91), a second core column (92) and a third core column (93); the first core column (91), the second core column (92) and the third core column (93) are each provided with an upper winding (2) and a lower winding (3); An upper horizontal iron (94) is provided between the top of the first core column (91), the top of the second core column (92), and the top of the third core column (93); a lower horizontal iron (95) is provided between the bottom of the first core column (91), the bottom of the second core column (92), and the bottom of the third core column (93).

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