Three-dimensional wound core strip optimization method, core and transformer

Abstract

The application relates to the technical field of transformer core manufacturing, and provides an optimization design method of a silicon steel three-dimensional wound core strip, which divides a core column section into eight trapezoidal levels. A maximum piece width A is determined first, then a first level piece width B is selected so that A+B is 0 or 5 at the end, and the start and tail are both B. C is selected based on B so that B+C is 0 or 5 at the end, and recursion is performed to eight levels, so that the end of each cutting width (the sum of the widths of adjacent pieces) is 0 or 5, and the number of different cutting widths in the longitudinal shearing process is not more than five. The method reduces the cutting specifications in the longitudinal shearing process, the tail width is standardized and can be directly used for manufacturing a laminated core, and material recycling is realized. The application also provides a core and a transformer.

Description

Technical Field

[0001] This invention belongs to the field of transformer core manufacturing technology, specifically relating to an optimized design method for silicon steel three-dimensional wound core strip, as well as a three-dimensional wound core manufactured using this method and a transformer containing the three-dimensional wound core. Background Technology

[0002] Three-dimensional wound core transformers are widely used in the field of distribution transformers due to their advantages such as perfectly symmetrical magnetic circuits, low no-load losses, and low noise. A three-dimensional wound core typically consists of three identical rectangular frames arranged at 120-degree angles to each other. Each frame is formed by continuously winding silicon steel strips of varying widths. To approximate a circular cross-section and improve the fill factor, the core column cross-section employs a multi-stage trapezoidal structure design, commonly with seven or eight stages.

[0003] In existing strip cutting design methods, the starting and ending strip widths are independently set for each trapezoidal section, and multiple cutting width specifications are set at 0.5 mm intervals during the slitting process. Taking an eight-stage iron core as an example, the slitting process requires eight different strip widths. This design leads to the following technical problems: First, the slitting process involves frequent blade changes, and the strip lengths of each specification vary significantly, resulting in a large number of short tail pieces with inconsistent widths, making them unsuitable for winding the same iron core or other types of iron cores, leading to long-term stockpiling. Second, the large amount of tail pieces directly reduces the utilization rate of silicon steel raw materials and increases manufacturing costs. Third, stockpiled tail pieces occupy production space, increasing the complexity of warehousing management and production scheduling.

[0004] Chinese patent CN106024371B discloses a six-segment, seven-level equal-length cutting method for three-dimensional coiled iron cores. This method achieves equal-length strips by ensuring the sum of the lengths of the first and sixth levels equals the lengths of the other levels, thus reducing excess material during the cutting stage. However, this method only focuses on optimizing the length direction and does not address the issues of diverse cutting widths and unusable tail material widths in the slitting process. Industry technical literature, "Practical Cutting Calculation Method for Three-Dimensional Coiled Iron Core Factories," proposes extending the conventional practice of keeping the last digit of the width in planar stacked iron cores to 3D coiled iron cores. It adjusts the angle value of each level to ensure the tail digit of the single-level strip width is 0 or 5. However, its design logic involves independent adjustment at each level, still failing to solve the problem of diverse cutting widths in the slitting process, and the tail material only reduces inventory without achieving resource utilization. Summary of the Invention

[0005] This invention aims to solve the problems of material waste accumulation and low material utilization caused by the numerous cutting width specifications in the slitting process of existing three-dimensional wound core strip designs. It provides an optimized method for three-dimensional wound core strip, core, and transformer. Under the premise of ensuring that the core filling coefficient remains unchanged, it reduces the variety of cutting widths in the slitting process and makes the remaining material have a standardized width, which can be directly used for the manufacturing of laminated cores of dry-type transformers or oil-immersed transformers, thereby realizing the recycling of material across products.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, this invention proposes an optimized design method for silicon steel three-dimensional coiled core strip, which divides the core column cross-section of the three-dimensional coiled core into 8 trapezoidal cross-section levels, including the following steps: Step 1: Calculate and determine the maximum sheet width A based on the circumcircle diameter of the core column and the core filling coefficient; Step 2: Select the first-level sheet width B, so that the last digit of the sum of the maximum sheet width A and the first-level sheet width B is the preset last digit value, and make one roll of the two adjacent rolls of material as the start and the other roll as the end, both using the first-level sheet width B; wherein, the sum of the maximum sheet width A and the first-level sheet width B is the first cutting width. Step 3: Using the first-level sheet width B as the base sheet width, select the second-level sheet width C such that the last digit of the sum of the first-level sheet width B and the second-level sheet width C is the preset last digit value; the sum of the first-level sheet width B and the second-level sheet width C is the second cutting width. Step 4: Repeat the recursive logic of Step 3, using the newly selected secondary sheet width in each round as the base sheet width for the next round, and continue to select the next secondary sheet width until the sheet width design of all 8 trapezoidal cross-section levels is completed; the sum of two adjacent sheet widths in each round constitutes a cutting width. Through the above hierarchical recursive design, the last digit of each cut width is the preset last digit value, and the number of different cut widths in the slitting process does not exceed 5.

[0007] Preferably, the preset last digit value is 0 or 5.

[0008] Preferably, in step 2, the total weight of the strip group using the maximum strip width A and the first-stage strip width B accounts for 30% to 35% of the total weight of the entire core.

[0009] Preferably, in step 3, the total weight of the strip group using the first stage strip width B and the second stage strip width C accounts for 25% to 30% of the total weight of the entire core.

[0010] Preferably, the last digit of all designed cutting width specifications is the preset last digit value.

[0011] Preferably, the method further includes step 5: collecting the remaining strip material after cutting, whose width ends at the preset last digit, for use in the manufacturing of laminated cores for dry-type transformers or oil-immersed transformers.

[0012] Preferably, the strip is a cold-rolled grain-oriented silicon steel strip.

[0013] Secondly, the present invention also proposes a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-mentioned optimized design method for silicon steel three-dimensional coiled core strip.

[0014] Thirdly, the present invention also proposes a three-dimensional wound core, which uses the above-mentioned optimized design method for silicon steel three-dimensional wound core strip to determine the strip width, and then longitudinally shears and winds the silicon steel strip according to the determined strip width to form the core.

[0015] Fourthly, the present invention also proposes a transformer comprising the aforementioned three-dimensional wound core.

[0016] The beneficial effects of this invention are: In traditional designs, the width of each stage is determined independently, with no mathematical correlation between the width values ​​of each stage. This results in a discrete and irregular distribution of cutting widths during the slitting process. This invention introduces a last-order constraint based on the sum of the widths of adjacent stages. Instead of being independent, the widths of each stage are recursively determined through a sequence of A+B, B+C, C+D, D+E, E+F, creating a regular recursive relationship and converging the cutting width values ​​to a few specifications. This reduction in cutting width during the slitting process directly lowers the blade change frequency and material arrangement complexity, reducing the types and quantities of waste material generated at the source.

[0017] This invention requires that the last digit of all lamination widths be uniformly set to a preset value, preferably 0 or 5, so that the width of the remaining scrap material perfectly matches the standard lamination width commonly used in lamination cores of dry-type or oil-immersed transformers. Therefore, these scrap materials can be directly used in the lamination core production line without any further processing, completing the transformation from waste to resource. While existing technologies may round the lamination width to 0 or 5, their purpose is merely to reduce inventory; they do not recognize that this rounding can open up a waste material recycling channel between three-dimensional wound cores and lamination cores, nor has it been included as a design objective.

[0018] This invention further defines the range of weight proportions of each strip group relative to the total core weight. This feature is significant because if the weight proportion of the dominant strip width (i.e., the strip width with the highest usage) is too low when the variety of strip widths is reduced, the actual benefits of reducing strip width types, such as fewer tool changes and simplified inventory, will be greatly diminished. By controlling the weight proportion of each strip group, the reduction in strip width types is ensured to be accurately reflected in the mainstream of material consumption, making the optimization scheme both economically and practically significant in production.

[0019] Since the sheet width design of this invention is still based on the original trapezoidal division of the core cross-section, and the filling area of ​​each trapezoid is not changed during the recursive process, the magnetic circuit cross-sectional area, filling coefficient, and electromagnetic performance of the core remain consistent with the original design. At the same time, due to the reduction in sheet width types and the utilization of leftover materials, raw material costs, warehousing costs, and management costs are significantly reduced. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the eight-level trapezoidal cross-section of the three-dimensional wound iron core column in an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the rectangular strip being obliquely cut to form the starting and ending pieces in an embodiment of the present invention. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] First, some of the terms used in this invention will be explained to facilitate understanding.

[0024] Trapezoidal cross-section level or level: refers to the number of trapezoidal blocks into which the cross-section of a core column of a three-dimensional rolled iron core is divided, with each level corresponding to a specific trapezoidal cross-section.

[0025] Strip width: refers to the width of a single coil of silicon steel strip, which is also the length of the base of the trapezoidal section parallel to the center line of the core. Each trapezoidal section has two strip widths: the starting strip width and the ending strip width.

[0026] Cutting width (or strip width): refers to the actual width of the rectangular strip cut during the slitting process. For example... Figure 2 As shown, a rectangular strip is cut into two trapezoids by a diagonal line. The width of the rectangle is equal to the sum of the bases of the two trapezoids; that is, the cutting width is equal to the sum of the starting width and the ending width of that stage. In the recursive design of this invention, the cutting width is also equal to the sum of the widths of two adjacent pieces (e.g., the sum of the maximum piece width A and the first-stage piece width B, the sum of the first-stage piece width B and the second-stage piece width C, etc.). This invention reduces the frequency of tool changes by reducing the variety of cutting widths in the slitting process. The same cutting width can be obtained through a curved cutting method to achieve multiple different starting and ending width distributions without affecting the statistical analysis of cutting width types.

[0027] Maximum strip width A: refers to the strip width of the first trapezoid in the core cross section, which is usually also the strip width with the largest value.

[0028] Base sheet width: In recursive design, the known sheet width used to calculate the next level of cutting width. In each round of recursion, the sum of the base sheet width of the current round and the newly selected secondary sheet width of the next level must satisfy the last constraint, and then the new secondary sheet width becomes the base sheet width of the next round.

[0029] The preset last digit value refers to the last digit of the cutting width value, which is preferably 0 or 5 in this invention. Example

[0030] This embodiment uses a set of actual design data as an example for illustration. The design divides the core column cross-section into 8 trapezoidal levels. The starting width, ending width, and cutting width (i.e., the sum of the starting width and ending width) of each level are shown in the table below:

[0031] As shown in the table, the last digit of all cutting widths is either 0 or 5, meeting the standardization requirements. There are five different values ​​for the cutting width in the slitting process: 250, 395, 445, 325, and 135. Among them, the cutting widths for levels 1 (71, 179) and 7 (146, 104) are both 250 mm. Although their starting and ending width distributions differ, the slitting process only needs to set one cutting width of 250 mm. Subsequent curve cutting can then yield different starting and ending width distributions, eliminating the need for additional cutting width specifications in the slitting process. Therefore, only one cutting width of 250 mm is required. The cutting widths for levels 2 (179, 216) and 5 (216, 179) are both 395 mm, and their starting and ending width values ​​are interchangeable. These can be obtained by adjusting the beveling position using strips of the same width. Therefore, only one specification is needed for the 395 mm width. Similarly, the cutting widths for grades 3 (216, 229) and 4 (229, 216) are both 445 mm, requiring only one specification. Grades 6 (325 mm) and 8 (135 mm) each require one specification. In total, five different cutting width specifications are needed: one for 250 mm, one for 395 mm, one for 445 mm, one for 325 mm, and one for 135 mm.

[0032] The above design data verifies the recursive logic of this invention. Starting with the maximum film width A = 229 mm (corresponding to the tail film width of level 3 or the starting film width of level 4), the first level film width B = 216 mm is selected, such that A + B = 445 mm (last digit 5). Based on B = 216 mm, the second level film width C = 179 mm is selected, such that B + C = 395 mm (last digit 5). Based on C = 179 mm, the third level film width D = 146 mm is selected, such that C + D = 325 mm (last digit 5). Based on D = 146 mm, the fourth level film width E = 104 mm is selected, such that D + E = 250 mm (last digit 0). Based on E = 104 mm, the fifth level film width F = 31 mm is selected, such that E + F = 135 mm (last digit 5). The recursive sequence of cutting widths is 445, 395, 325, 250, and 135, a total of 5 values.

[0033] In this embodiment, a continuous transition is achieved between adjacent levels by sharing a common sheet width. For example, the tail sheet width 179 of level 1 is the same as the starting sheet width 179 of level 2; the tail sheet width 216 of level 2 is the same as the starting sheet width 216 of level 3; the tail sheet width 229 of level 3 is the same as the starting sheet width 229 of level 4; the tail sheet width 216 of level 4 is the same as the starting sheet width 216 of level 5; the tail sheet width 179 of level 5 is the same as the starting sheet width 179 of level 6; the tail sheet width 146 of level 6 is the same as the starting sheet width 146 of level 7; and the tail sheet width 104 of level 7 is the same as the starting sheet width 104 of level 8. The design of sharing a sheet width between adjacent levels ensures the geometric continuity and rationality of the trapezoidal cross-sections at each level. The reason why the types of cutting widths can be reduced to 5 is that after the recursive design of each level of sheet width, the last digit of the sum of adjacent sheet widths is 0 or 5, and the same value appears repeatedly in multiple levels (such as 250 mm appearing in level 1 and level 7, 395 mm appearing in level 2 and level 5, and 445 mm appearing in level 3 and level 4), thus reducing the cutting widths required for 8 levels to 5 specifications.

[0034] The remaining short strips of material with widths of 250 mm, 395 mm, 445 mm, 325 mm, and 135 mm after cutting can be directly used in the production of laminated cores for dry-type or oil-immersed transformers after sorting and collecting. Since the commonly used lamination widths for laminated cores include the above specifications, these leftover materials do not need to be re-cut and can be used.

[0035] This embodiment verifies that the method of the present invention can effectively reduce the variety of cutting widths in the slitting process and achieve standardization of tail material while ensuring that the filling coefficient remains unchanged. Example

[0036] This embodiment uses a three-phase, three-dimensional wound core transformer with a capacity of 5500 kVA as an example to illustrate the general parameter design process. The outer diameter of the transformer core column is designed to be 397 mm, the target value of the fill factor is 0.95, an eight-stage trapezoidal cross-section design is adopted, and the preset last value is 0 or 5.

[0037] Step 1: Calculate and determine the maximum sheet width A based on the circumcircle diameter of the core column and the core filling coefficient. Geometric calculations show that the maximum sheet width A is equal to 229 mm.

[0038] Step 2: Select the first-stage strip width B such that the last digit of the sum of the maximum strip width A and the first-stage strip width B is 0 or 5, i.e., the last digit of 229 plus B is 0 or 5. If the first-stage strip width B is selected to be 216 mm, then 229 plus 216 equals 445, with a last digit of 5. The total weight of the strip group corresponding to strip widths of 229 mm and 216 mm (i.e., a cutting width of 445 mm) is calculated to be approximately 32% of the total core weight, which is greater than 30%.

[0039] Step 3: Using the first-stage strip width B of 216 mm as the base strip width, select the second-stage strip width C such that the last digit of the sum of the base strip width and the second-stage strip width is 0 or 5, i.e., the last digit of 216 plus C is 0 or 5. If the second-stage strip width C is selected to be 179 mm, then 216 plus 179 equals 395, with a last digit of 5. The total weight of this strip (cut width 395 mm) accounts for approximately 27% of the total core weight, which is greater than 25%.

[0040] Step 4: Repeat the recursive logic of Step 3. Using the second-stage strip width C of 179 mm as a base, select the third-stage strip width D such that the last digit of 179 plus D is 0 or 5. If D is chosen to be 146 mm, then 179 plus 146 equals 325, with a last digit of 5. The total weight of this strip (cut width 325 mm) accounts for approximately 20%.

[0041] Based on a third-stage strip width D of 146 mm, a fourth-stage strip width E is chosen such that the sum of 146 and E ends in 0 or 5. Choosing E to equal 104 mm, 146 plus 104 equals 250, ending in 0. The total weight of this strip (cut width 250 mm) accounts for approximately 15%.

[0042] Based on a fourth-level strip width E of 104 mm, a fifth-level strip width F is selected such that the last digit of 104 plus F is 0 or 5. If F is chosen to be 31 mm, then 104 plus 31 equals 135, ending in 5. The total weight of this strip (cut width 135 mm) accounts for approximately 8%.

[0043] Thus, the sheet width sequence is obtained recursively: 229, 216, 179, 146, 104, 31, corresponding to cutting widths of 445, 395, 325, 250, and 135. All cutting widths end in 0 or 5, meaning there are actually 5 different cutting widths in the slitting process.

[0044] The remaining width after cutting is a short strip of material of the above specifications, which can be collected and used directly for the production of laminated iron cores.

[0045] This embodiment shows that by using the recursive design method of the present invention, the cutting width types of the slitting process can be controlled to 5 types while ensuring that the filling coefficient remains basically unchanged, and the last part of all widths is standardized.

[0046] This invention can be directly integrated into the CNC programming system of a silicon steel slitting line. By automatically calculating and estimating the sheet width and cutting width specifications and outputting cutting instructions, it reduces the frequency of tool changes in the slitting process, achieving material optimization and tailings management. This invention is applicable to all manufacturers of oil-immersed and dry-type transformers using three-dimensional wound cores and has broad industrial application prospects.

[0047] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. An optimized design method for silicon steel three-dimensional coiled core strip, characterized in that, The core column cross-section of the three-dimensional rolled iron core is divided into 8 trapezoidal cross-section levels, including the following steps: Step 1: Calculate and determine the maximum sheet width A based on the circumcircle diameter of the core column and the core filling coefficient; Step 2: Select the first-level sheet width B, so that the last digit of the sum of the maximum sheet width A and the first-level sheet width B is the preset last digit value, and make one roll of the two adjacent rolls of material as the start and the other roll as the end, both using the first-level sheet width B; wherein, the sum of the maximum sheet width A and the first-level sheet width B is the first cutting width. Step 3: Using the first-level sheet width B as the base sheet width, select the second-level sheet width C such that the last digit of the sum of the first-level sheet width B and the second-level sheet width C is the preset last digit value; the sum of the first-level sheet width B and the second-level sheet width C is the second cutting width. Step 4: Repeat the recursive logic of Step 3, using the newly selected secondary sheet width in each round as the base sheet width for the next round, and continue to select the next secondary sheet width until the sheet width design of all 8 trapezoidal cross-section levels is completed; the sum of two adjacent sheet widths in each round constitutes a cutting width. Through the above hierarchical recursive design, the last digit of each cut width is the preset last digit value, and the number of different cut widths in the slitting process does not exceed 5.

2. The optimized design method for silicon steel three-dimensional coiled core strip according to claim 1, characterized in that, The preset last digit value is 0 or 5.

3. The optimized design method for silicon steel three-dimensional coiled core strip according to claim 1, characterized in that, In step 2, the total weight of the strip group using the maximum strip width A and the first-stage strip width B accounts for 30% to 35% of the total weight of the entire core.

4. The optimized design method for silicon steel three-dimensional coiled core strip according to claim 1, characterized in that, In step 3, the total weight of the strip group using the first stage strip width B and the second stage strip width C accounts for 25% to 30% of the total weight of the entire core.

5. The optimized design method for silicon steel three-dimensional coiled core strip according to claim 1, characterized in that, The last digit of all designed cutting width specifications is the preset last digit value.

6. The optimized design method for silicon steel three-dimensional coiled core strip according to claim 1, characterized in that, It also includes step 5: collecting the remaining strip material after cutting, whose width ends at the preset last digit, for use in the manufacturing of laminated cores for dry-type transformers or oil-immersed transformers.

7. The optimized design method for silicon steel three-dimensional coiled core strip according to claim 1, characterized in that, The strip material is cold-rolled grain-oriented silicon steel strip.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements the optimized design method for silicon steel three-dimensional coiled core strip as described in any one of claims 1 to 7.

9. A three-dimensional wound iron core, characterized in that, The strip width is determined by the optimization design method of silicon steel three-dimensional coiled core strip according to any one of claims 1 to 7, and the silicon steel strip is longitudinally cut and wound according to the determined strip width to form the core.

10. A transformer, characterized in that, Includes the three-dimensional wound core as described in claim 9.

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