A batch cross-compensation winding method to improve the flatness of thick coil windings

Abstract

This invention discloses a batch-cross-compensation winding method for improving the flatness of thick coil windings, comprising the following steps: identifying and calibrating the direction of thickness deviation of the superconducting tape; decomposing the total number of winding layers of the entire coil into multiple winding batches; performing batch winding in an alternating cross-position manner; and measuring and verifying the cross-section of the wound coil. This invention achieves active compensation for tape thickness deviation, decomposing the winding process into several clearly defined batches. The number of layers N in each batch can be quantitatively calculated based on the actual tape deviation and allowable deformation tolerance. Furthermore, only one tape flipping and joint fabrication is required between batches, without changing the main process parameters such as winding speed and tension control, resulting in high compatibility with existing winding equipment. It significantly improves the geometric consistency and electromagnetic performance of the coil. By eliminating the trapezoidal cross-section, the interlayer stress distribution inside the coil is more uniform, ensuring the excitation efficiency and magnetic field accuracy of the superconducting magnet.

Description

Technical Field

[0001] This invention relates to the field of superconducting coil winding technology, and in particular to a batch cross-compensation winding method for improving the flatness of thick coil windings. Background Technology

[0002] As the core component of a superconducting magnet system, the winding precision of the superconducting coil directly determines the quality of the magnetic field distribution generated by the magnet. In high-field solenoid superconducting magnets, multi-layered close-wound structures are typically used to achieve higher current density and magnetic field strength. In recent years, with the continuous maturation of high-temperature superconducting tape (such as YBCO) manufacturing processes, wide-width thin superconducting tapes (e.g., 6mm × 0.09mm) have gradually become the mainstream choice for winding high-field coreless or semi-core superconducting coils due to their excellent current-carrying capacity and mechanical properties.

[0003] However, in practical engineering applications, the thickness of superconducting tapes is not absolutely uniform. Taking a tape with a nominal thickness of 0.09 mm as an example, due to fluctuations in the manufacturing process, the tape often exhibits a thickness deviation at the micrometer level along its width. Typically, one side will be about one percent thicker than the other, or about 0.9 μm. Although this value is almost negligible in a single-layer tape, in the process of winding multi-layer solenoid coils, the deviation accumulates layer by layer as the number of layers increases. Specifically, after winding several hundred layers, the total thickness accumulated on the thicker side of the tape will be significantly greater than that on the thinner side, causing the overall cross-section of the coil to gradually evolve from the designed rectangle to a trapezoid. This phenomenon is particularly severe in thick coil structures with thousands of layers, and can even lead to a series of problems such as coil geometric distortion, uneven internal stress distribution, deformation of cooling channels, and final magnetic field center shift.

[0004] Currently, neither industry nor academia has developed a systematic solution to the trapezoidal cross-section problem caused by the aforementioned thickness accumulation. Existing processes typically employ two methods: one is to screen the strip for thickness along its entire length before winding, eliminating batches with significant deviations, but this greatly increases manufacturing costs and material waste; the other is to correct the thickness after winding through machining or applying external pressure, but this method easily damages the superconducting layer or destroys the insulation structure, and cannot fundamentally eliminate the internally accumulated deviations. In addition, some researchers have attempted to locally compensate for thickness differences by adjusting the winding tension, but the compensation capability of tension control is limited and it is prone to inducing new deformation modes, resulting in unsatisfactory results.

[0005] This demonstrates that existing technologies generally lack a process method capable of actively identifying and eliminating the cumulative effect of strip thickness deviations during the winding process. Faced with the demand for high-density winding with hundreds or even thousands of layers, achieving rectangular control of the coil cross-section has become a key technological bottleneck restricting the improvement of high-precision superconducting coil manufacturing capabilities. Summary of the Invention

[0006] This invention addresses the problems existing in the prior art by proposing a batch cross-compensation winding method to improve the flatness of thick coil winding. The purpose is to solve the problem that the prior art lacks a process method that can actively identify and eliminate the cumulative effect of strip thickness deviation during the winding process.

[0007] To address the problems existing in the prior art, the present invention proposes the following technical solutions: A batch-cross-compensation winding method for improving the flatness of thick coil windings, characterized by the following steps: Step 1: Identify and calibrate the direction of thickness deviation of the superconducting tape; Step 2: Divide the total number of winding layers of the entire coil into multiple winding batches; Step 3: Wind the wires in batches using an alternating, cross-positioning method; Step 4: Measure and verify the cross-section of the wound coil.

[0008] Furthermore, the identification and calibration of the thickness deviation direction of the superconducting tape in step one is as follows; (1) Obtain the superconducting tape to be wound, with a nominal thickness of H and a width of W; (2) Along the width direction of the strip, use a high-precision thickness measuring device to measure its thickness distribution, identify the side with relatively larger thickness, referred to as the "thick side", and the side with relatively smaller thickness, referred to as the "thin side"; (3) Make visible marks on the edge or back of the strip to distinguish the orientation of the thick side and the thin side during subsequent winding.

[0009] Furthermore, step two involves decomposing the total number of winding layers of the entire coil into multiple winding batches, as detailed below; (1) Based on the statistical mean δ of the strip thickness deviation and the allowable cross-sectional shape tolerance of the coil, determine the number of winding layers N and the total number of winding layers L_total for a single batch, so that the trapezoidal tilt caused by the accumulation of thickness deviation within N layers is still within an acceptable range. (2) Divide the total number of winding layers L_total into M batches, with each batch having N layers or slightly adjusted according to the actual winding progress, where N=L_total / M; M is an even number; Furthermore, step three involves winding the wire in batches using an alternating cross-positioning method, as detailed below; (1) In the first batch of winding, the thick side of the strip is oriented towards the upper or lower end of the coil axis, and the thin side is oriented towards the lower or upper end of the coil axis, and N layers are wound. (2) After the first batch of winding is completed, a joint is made on the strip and interlayer insulation is done; the thin side and thin side of the joint are opposite to the thin side and thin side of the strip being joined, forming a complementary relationship; (3) Using the reversed strip orientation, continue winding the next batch of N layers; (4) Repeat the above process of “winding-jointing-reversing the strip orientation” until all M batches of winding are completed.

[0010] Furthermore, step four involves measuring and verifying the cross-section of the wound coil, as detailed below: (1) After all batches of winding are completed, the axial cross-sectional profile of the coil is measured to obtain the actual cross-sectional shape; (2) Compare the measured cross-sectional shape with the designed rectangular cross-section, and calculate the trapezoidal tilt angle or the cumulative thickness deviation; (3) If the measured cross-sectional shape meets the preset tolerance requirements, the winding process is confirmed to be qualified; if there is still significant trapezoidal deformation, the number of layers N or the flipping strategy of a single batch is adjusted according to the direction of residual deviation, and iterative optimization is carried out in subsequent coil manufacturing. Advantages and effects of the present invention

[0011] This invention, by proposing a batch-by-batch, cross-positioning winding method, systematically solves for the first time the long-standing technical problem of trapezoidal coil cross-section caused by the gradual amplification of minute thickness deviations in superconducting tape during multi-layer dense winding. Compared with existing technologies, this invention has the following significant advantages: First, it achieves proactive compensation for strip thickness deviations, rather than passive acceptance or screening. Traditional methods rely on high-precision strips or post-processing correction, while this invention achieves this by rotating the strip orientation in batches during the winding process, allowing the thick and thin sides to cancel each other out in different batches. This enables even strips with conventional manufacturing deviations to be wound into coils with a near-rectangular cross-section, significantly reducing reliance on strip precision and raw material costs.

[0012] Secondly, the process is quantifiable and easy to operate. This invention decomposes the winding process into several clearly defined batches. The number of layers N in each batch can be quantitatively calculated based on the actual strip deviation and allowable deformation tolerance. Moreover, only one strip flipping and joint fabrication is required between batches, without changing the main process parameters such as winding speed and tension control, making it highly compatible with existing winding equipment.

[0013] Third, it significantly improves the geometric consistency and electromagnetic performance of the coil. By eliminating the trapezoidal cross-section, the interlayer stress distribution inside the coil is more uniform, the cooling channels maintain their designed shape, and the central axis of the magnetic field does not shift, ensuring the excitation efficiency and magnetic field accuracy of the superconducting magnet. In addition, the uniform cross-section also helps to reduce local stress concentration, lowering the risk of critical current degradation and quench probability of the superconducting tape.

[0014] Fourth, it has closed-loop optimization capabilities. The cross-sectional measurement results in step four can be fed back to the batch layer design in step two, forming an iterative mechanism of "manufacturing-measurement-optimization" to further improve the winding quality of subsequent coils. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the overall process flow of the present invention. Figure 2 This is a schematic diagram of the thickness deviation of the superconducting tape of the present invention (distribution of the thick side and thin side in the width direction). Figure 3 This is a schematic diagram showing that the cross-section of the coil after multi-layer winding is trapezoidal when the method of this invention is not used; Figure 4 This is a schematic diagram of the batch cross-positioning joint in this invention; Figure 5 This is a schematic diagram of the batch-by-batch cross-rotation winding of the integral coil in this invention; Figure 6 This is a schematic diagram showing the effect of restoring the coil cross-section to a rectangle after using the method of the present invention. Detailed Implementation Innovation of this invention

[0016] 1. Proactive Compensation for Strip Thickness Deviation: This method proposes proactively adjusting the strip orientation during winding to compensate for thickness deviations, rather than relying on strip selection or post-construction correction. It identifies the "thick side" and "thin side" of the strip, divides the total number of winding layers into batches, and flips the strip orientation between adjacent batches, causing the thick and thin sides to alternate, thus achieving mutual cancellation of deviations at the overall level. This reduces the stringent requirements for the uniformity of the strip thickness, saves raw material costs, and effectively suppresses geometric distortion of the coil cross-section.

[0017] 2. Batch-by-batch refined control of the winding process: By quantitatively analyzing the statistical characteristics of strip thickness deviation and coil cross-sectional tolerance, the number of winding layers in a single batch is determined, achieving refined process control. The number of layers N per batch is calculated based on the average deviation and allowable tolerance, ensuring that the cumulative deviation within a single batch does not exceed the tolerance limit; the total number of batches M is set to an even number to ensure overall deviation offsetting. This improves winding flatness and interlayer consistency, avoiding excessive local deformation.

[0018] 3. Simple and easy-to-operate process: Only strip flipping and splicing are required during batch transitions, without changing core process parameters such as winding speed and tension, and it is compatible with existing production equipment. It is easy to implement on existing production lines, has low modification costs, low barriers to entry, and is suitable for large-scale production.

[0019] 4. Closed-Loop Optimization and Iterative Improvement: A closed-loop mechanism of "manufacturing-measurement-optimization" is introduced, using measured coil cross-sectional geometric data as feedback to adjust batch strategies and flipping schemes. The measured cross-sectional data after winding is used to optimize the layer design and flipping logic of subsequent batches, adapting to the non-uniform distribution of strip deviations. This enables continuous process improvement, ensuring long-term stability of coil geometry and electromagnetic performance. Design principle of the invention

[0020] 1. In the winding process of multi-layer tightly wound solenoid coils, the geometric accuracy of the strip is the core factor determining the final cross-sectional shape of the coil. For example... Figure 2 , Figure 3 As shown, for a high-temperature superconducting tape with a nominal thickness of 0.09 mm and a width of 6 mm, the thickness distribution in the width direction is usually not absolutely uniform due to fluctuations in the extrusion, coating, or deposition processes during manufacturing. The typical deviation is between a few tenths of a micrometer and a few micrometers. This deviation can cause negligible thickness changes in a single layer relative to the overall layer thickness. However, in the process of accumulating hundreds or even thousands of layers, the additional 0.9 μm stacking of each layer will result in the total thickness on one side of the coil being several millimeters greater than that on the other side, thus forming a distinct trapezoidal cross-section.

[0021] 2. Traditional winding processes assume uniform strip thickness and do not consider mechanisms to suppress the accumulation of layer-by-layer deviations in the process design. The core design principle proposed in this invention lies in transforming "deviation accumulation" into "deviation cancellation." For example... Figure 4 , Figure 6 As shown, by decomposing the total number of winding layers into several independent winding batches, and flipping the thick and thin sides of the strip 180° between batches, the extra thickness caused by the thick side in the previous batch is compensated for by the thickness reduction caused by the thin side in the subsequent batch. After an integer number of alternating windings, the total thickness deviation is controlled within the cumulative amount of a single batch, thereby achieving a rectangular cross-section.

[0022] 3. In engineering implementation, the selection of the number of layers N in a single batch should follow these principles: Let the thickness difference between the thick and thin sides of the strip be Δh. After winding N layers, the height difference between one side of the coil and the other side will be approximately N·Δh. To ensure stability during the winding process and the final cross-sectional accuracy, N·Δh is usually set to not exceed the allowable axial unevenness or interlayer offset tolerance of the coil design. For example, when Δh = 0.9 μm and the allowable cumulative deviation is 0.1 mm, N can be taken as approximately 110 layers. In actual production, adjustments can be made flexibly according to the specific strip batch and coil requirements.

[0023] 4. When making joints between batches, pay attention to insulation and mechanical fixing to avoid the joint becoming a local stress concentration point. Also, after flipping the strip orientation, it is recommended to recalibrate the winding tension to ensure that the initial winding of subsequent batches closely adheres to the surface of the previous batch.

[0024] 5. If a slight trapezoidal shape is still found in the cross-section during the measurement after the coil is completed, the number of layers N in a single batch can be appropriately reduced in the next winding, or a finer-grained flipping strategy can be introduced between batches (e.g., flipping after each batch). Through the measurement feedback in step four, this process method has good adaptive optimization capabilities.

[0025] In summary, this invention provides a low-cost, highly reliable, and easily engineering-promotable method for improving the flatness of thick coil windings, which is particularly suitable for high-layer-number solenoid coils wound with wide-width thin-strip superconducting strips.

[0026] Based on the above principles, this invention designs a batch-cross-compensation winding method to improve the flatness of thick coil windings, such as... Figure 1-6 As shown, its characteristics include the following steps: Step 1: Identify and calibrate the direction of thickness deviation of the superconducting tape; Step 2: Divide the total number of winding layers of the entire coil into multiple winding batches; Step 3: Wind the wires in batches using an alternating, cross-positioning method; Step 4: Measure and verify the cross-section of the wound coil.

[0027] Furthermore, the identification and calibration of the thickness deviation direction of the superconducting tape in step one is as follows; (1) Obtain the superconducting tape to be wound, with a nominal thickness of H and a width of W; (2) Along the width direction of the strip, use a high-precision thickness measuring device to measure its thickness distribution, identify the side with relatively larger thickness, referred to as the "thick side", and the side with relatively smaller thickness, referred to as the "thin side"; (3) Make visible marks on the edge or back of the strip to distinguish the orientation of the thick side and the thin side during subsequent winding.

[0028] Furthermore, step two involves decomposing the total number of winding layers of the entire coil into multiple winding batches, as detailed below; (1) Based on the statistical mean δ of the strip thickness deviation and the allowable cross-sectional shape tolerance of the coil, determine the number of winding layers N and the total number of winding layers L_total for a single batch, so that the trapezoidal tilt caused by the accumulation of thickness deviation within N layers is still within an acceptable range. (2) Divide the total number of winding layers L_total into M batches, with each batch having N layers or slightly adjusted according to the actual winding progress, where N=L_total / M; M is an even number; Furthermore, step three involves winding the wire in batches using an alternating cross-positioning method, as detailed below; (1) In the first batch of winding, the thick side of the strip is oriented towards the upper or lower end of the coil axis, and the thin side is oriented towards the lower or upper end of the coil axis, and N layers are wound. (2) After the first batch of winding is completed, a joint is made on the strip and interlayer insulation is done; the thin side and thin side of the joint are opposite to the thin side and thin side of the strip being joined, forming a complementary relationship; (3) Using the reversed strip orientation, continue winding the next batch of N layers; (4) Repeat the above process of “winding-jointing-reversing the strip orientation” until all M batches of winding are completed.

[0029] Furthermore, step four involves measuring and verifying the cross-section of the wound coil, as detailed below: (1) After all batches of winding are completed, the axial cross-sectional profile of the coil is measured to obtain the actual cross-sectional shape; (2) Compare the measured cross-sectional shape with the designed rectangular cross-section, and calculate the trapezoidal tilt angle or the cumulative thickness deviation; (3) If the measured cross-sectional shape meets the preset tolerance requirements, the winding process is confirmed to be qualified; if there is still significant trapezoidal deformation, the number of layers N or the flipping strategy of a single batch is adjusted according to the direction of residual deviation, and iterative optimization is carried out in subsequent coil manufacturing.

[0030] Supplementary Note 1: Figure 3 It reveals a pressing and widespread engineering problem that urgently needs to be solved. It provides a crucial "target" for the subsequent introduction of the "solution" of this invention.

[0031] 2. Figure 3 The most direct and impactful information is that the cross-sectional shape has been distorted from an "ideal rectangle" to an "actual trapezoid." This directly highlights the seriousness of the problem—it is not a minor deviation, but a macroscopic defect sufficient to alter the overall geometry of the coil.

[0032] 3. Delving into the Mechanism of the Problem: Why does a trapezoidal shape occur? The key lies in the dynamic process of "accumulated deviation." Several factors need to be considered: Cause: A single superconducting tape exhibits micrometer-level thickness unevenness in its width direction (one side is slightly thicker than the other). This is an inherent limitation of the manufacturing process. Process: In the process of multi-layer (hundreds or thousands of layers) and tightly wound construction, each layer acts like a brick. If each brick has one side that is slightly thicker, then during the construction, this tiny deviation will be amplified and transmitted layer by layer along the same direction. Ultimately, along the winding axis, the deviation accumulates into a considerable dimensional difference, resulting in a cross-section that is wider at one end and narrower at the other, forming a trapezoid.

[0033] 4. Serious Consequences of Derivation Problems: The trapezoidal cross-section is not merely "ugly"; it triggers a series of cascading engineering and physics problems: Geometric distortion leads to overall coil structural instability, internal stress concentration, potentially reducing mechanical strength or causing localized damage. Asymmetrical winding distribution alters the current path, causing magnetic field distortion and deviating the magnetic field center from its design position. This is fatal for applications requiring extremely high magnetic field uniformity (such as MRI and scientific magnets). Space reserved for cooling channels and insulation may be compressed or deformed, affecting cooling efficiency and insulation reliability.

[0034] 5. Summary Figure 3 Strategic role in documents: Ultimately, Figure 3 The function of this invention can be summarized as: "Establishing the contradiction, leading to innovation." It vividly presents the fundamental contradiction between the "demand for high-precision coils" and the "cumulative error caused by inherent defects in the strip." It is precisely based on a profound understanding of this trapezoidal deformation mechanism that the necessity of this invention can be logically derived—that is, to actively correct this problem through a new winding method, compensation strategy, or control process (e.g., intelligently rotating or adjusting the strip direction during winding to offset the directional accumulation of deviations), thereby obtaining a cross-section close to an ideal rectangle. Therefore, Figure 3 It is a crucial diagram that connects the preceding and following sections. Only with a full understanding... Figure 3 Only after the problems are revealed will the value and ingenuity of the invention's method presented in subsequent documents become truly prominent and persuasive. Your summary—"used to 'raise the problem'"—perfectly captures its essence.

[0035] Supplementary Note 2: Figure 4Its core function is to visually demonstrate how the key process node in "batch-by-batch cross-positioning" technology—the batch-to-batch joint—specifically compensates for thickness deviations. It clarifies the following three progressive technical points through schematic diagrams: ① Demonstrating the physical structure of the joint: The diagram illustrates the specific joint form connecting the tail end of the previous batch of strip to the head end of the next batch, enabling the continuity of "batch-by-batch winding." ② Revealing the essence of "cross-positioning": This is... Figure 4 The most crucial value is that it clearly demonstrates that during the fabrication of this joint, the "thick side" of the previous batch of strip was intentionally aligned with the "thin side" of the subsequent batch (or vice versa). This conscious "thick-thin connection" is precisely the concrete manifestation of "cross-positioning" at the joint. ③ Clarifying the spatial logic of the compensation mechanism: Through the above-mentioned alignment method, Figure 4 This visualizes the abstract principle of "compensation." It shows that the radial dimension accumulation (bulge) caused by the "thick side" of the previous batch is "converted" at the joint into the starting point of the "thin side" of the next batch. Thus, when the next batch begins winding, its starting point's thin side naturally "embeds" or "fills" the excess space occupied by the thick side at the ending point of the previous batch. Looking at the entire winding's axial cross-section, this connection method disperses and staggers the thickness deviation of the strip (thick and thin sides) along the winding direction, rather than continuously accumulating at the same location. This significantly smooths the overall radial dimension of the winding, improving uniformity and reliability. In summary... Figure 4 It is a "visual bridge" that translates the core patent features of "batch production", "cross-positioning", and "thickness compensation" from a process concept into specific and operable joint manufacturing steps.

[0036] Supplementary Note 3 Figure 5 This paper demonstrates an advanced winding method for superconducting tape coils—the "batch cross-transposition winding method." The root cause of the problem is the inherent thickness variation in the width direction of superconducting tape (thicker on one side, thinner on the other). In traditional continuous winding, this variation accumulates layer by layer, causing the coil's cross-section to change from an ideal rectangle to a trapezoid, affecting the coil's mechanical and electromagnetic properties. The solution is batch winding: dividing the entire coil into multiple consecutive "batches," each containing N layers. Cross-transposition (flipping): After completing one batch, before starting the next batch, the tape is flipped 180 degrees around its axis: First batch: Thicker side of the tape facing up (assuming). Second batch: The tape is flipped, thicker side facing down. Subsequent batches: This alternating process is repeated.

[0037] Working Principle and Purpose: By actively and periodically flipping the strip, the "thick side" and "thin side" of the strip occupy different positions in the coil's radial direction in different batches. The "extra thickness" increase brought about by the thick side in one batch is partially offset by the "thickness reduction" brought about by the thin side in the next batch. After multiple batches of alternation, the cumulative effect of thickness deviation is averaged and controlled within an acceptable range, thereby restoring the overall cross-section of the coil to a near-perfect rectangle. The core innovation of this method lies in transforming manufacturing defects (thickness deviation) from a passively accumulated problem into a variable that can be actively compensated for and offset through process design. It does not require changing the strip itself; simply through a clever winding sequence, it significantly improves the geometric accuracy and uniformity of the coil, which is crucial for the manufacture of high-performance superconducting magnets.

[0038] Supplementary Note 4: like Figure 6 As shown, the coil cross-sectional shape is significantly improved after using the method of the present invention. Compared to Figure 3 The trapezoidal cross section shown demonstrates how the new method, through a batch-by-batch cross-compensation winding process, actively offsets the cumulative thickness deviation of the strip, thereby obtaining a flat and regular rectangular cross section. This proves the effectiveness of the scheme in controlling the cross section morphology.

[0039] It should be emphasized that the above specific embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. It should be noted that those skilled in the art, after reading this specification, can make relevant improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A batch cross-compensated winding method for improving the flatness of thick coil winding, characterized in that: Includes the following steps: Step 1: Identify and calibrate the direction of thickness deviation of the superconducting tape; Step 2: Divide the total number of winding layers of the entire coil into multiple winding batches; Step 3: Wind the wires in batches using an alternating, cross-positioning method; Step 4: Measure and verify the cross-section of the wound coil.

2. The method of claim 1 wherein the method is a batch cross-compensation method for improving flatness of thick coil winding, characterized in that: The identification and calibration of the thickness deviation direction of the superconducting tape in step one is as follows; (1) Obtain the superconducting tape to be wound, with a nominal thickness of H and a width of W; (2) Along the width direction of the strip, use a high-precision thickness measuring device to measure its thickness distribution, identify the side with relatively larger thickness, referred to as the "thick side", and the side with relatively smaller thickness, referred to as the "thin side"; (3) Make visible marks on the edge or back of the strip to distinguish the orientation of the thick side and the thin side during subsequent winding.

3. The method of claim 1 wherein: the method is a batch cross-compensation method for improving flatness of thick coil winding. Step two involves decomposing the total number of winding layers of the entire coil into multiple winding batches, as detailed below; (1) Based on the statistical mean δ of the strip thickness deviation and the allowable cross-sectional shape tolerance of the coil, determine the number of winding layers N and the total number of winding layers L_total for a single batch, so that the trapezoidal tilt caused by the accumulation of thickness deviation within N layers is still within an acceptable range. (2) Divide the total number of winding layers L_total into M batches, with each batch having N layers or slightly adjusted according to the actual winding progress, where N=L_total / M; M is an even number.

4. The method of claim 1 wherein: the method is a batch cross-compensation method for improving flatness of thick coil winding. Step three involves winding the wires in batches using an alternating cross-positioning method, as detailed below; (1) In the first batch of winding, the thick side of the strip is oriented towards the upper or lower end of the coil axis, and the thin side is oriented towards the lower or upper end of the coil axis, and N layers are wound. (2) After the first batch of winding is completed, a joint is made on the strip and interlayer insulation is done; the thin side and thin side of the joint are opposite to the thin side and thin side of the strip being joined, forming a complementary relationship; (3) Using the reversed strip orientation, continue winding the next batch of N layers; (4) Repeat the above process of "winding-jointing-reversing the strip orientation" until all M batches of winding are completed.

5. The method of claim 1 wherein: the method is a batch cross-compensation method for improving flatness of thick coil winding. The fourth step involves measuring and verifying the cross-section of the wound coil, as detailed below: (1) After all batches of winding are completed, the axial cross-sectional profile of the coil is measured to obtain the actual cross-sectional shape; (2) Compare the measured cross-sectional shape with the designed rectangular cross-section, and calculate the trapezoidal tilt angle or the cumulative thickness deviation; (3) If the measured cross-sectional shape meets the preset tolerance requirements, the winding process is confirmed to be qualified; if there is still significant trapezoidal deformation, the number of layers N or the flipping strategy of a single batch is adjusted according to the direction of residual deviation, and iterative optimization is carried out in subsequent coil manufacturing.

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