Three-dimensional braided multifunctional litz cable, power inductor and end processing method

Abstract

The application discloses a three-dimensional braided multifunctional Litz cable, a power inductor and an end processing method. The cable comprises a non-laminated integrated mesh topology formed by interweaving a plurality of independent yarn systems in the same three-dimensional braiding process, and contains a conductive area, a magnetic control area, an insulating area and a structural area. Wherein, the magnetic fiber bundle and the conductive fiber bundle are interpenetrated to form an array distribution mechanical interlocking node, and a continuous three-dimensional magnetic flux topology network is constructed to provide intrinsic electromagnetic shielding. The application solves the problems of large interface thermal resistance, high high-frequency loss and poor flexibility of the existing laminated structure, and has low loss, high reliability and excellent flexibility.

Description

Technical Field

[0001] This invention relates to the field of power electronic transmission and electromagnetic components, and in particular to a three-dimensional braided multifunctional Litz cable, a power inductor, and an end-processing method. Background Technology

[0002] With the development of new energy vehicles, aerospace, and high-end equipment manufacturing, higher requirements are being placed on the high-frequency performance, power density, and reliability of power transmission systems. While traditional Litz wires alleviate the skin effect at high frequencies to some extent through multi-strand stranding, their shielding layer is typically wrapped with metal foil or metal mesh, forming a distinct "layered interface." This physical interface not only increases contact resistance and interfacial thermal resistance but also easily leads to interlayer delamination under complex vibration environments, resulting in lower reliability.

[0003] In existing technologies, such as Alva Industries, attempts have been made to manufacture motor components using electromagnetic pads combined with embedded conductors. However, these are essentially still layered structures and fail to achieve deep coupling between conductive current and magnetic circuits at the microscale. Furthermore, while existing 3D printing technologies can manufacture complex shapes for magnetic components such as power inductors, they suffer from weak material bonding, high microscopic porosity, and difficulty in achieving a smooth gradient change in magnetic permeability.

[0004] In addition, for the end connections of three-dimensional braided cables, due to the complex mechanical interlocking structure of the internal fibers, traditional mechanical stripping methods are difficult to effectively separate the fiber bundles, resulting in poor welding quality and high contact resistance.

[0005] Therefore, there is an urgent need for an integrated cable and inductor manufacturing solution that reconstructs the microstructure to solve the aforementioned problems of interface bonding, high-frequency loss, and connection process. Summary of the Invention

[0006] The present invention aims to solve the above-mentioned technical problems and provides a three-dimensional braided multifunctional Litz cable, power inductor and end treatment method. By constructing a microscale mechanical interlocking topology, the interlayer interface is eliminated and the electromagnetic performance and mechanical reliability are improved.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a three-dimensional braided multifunctional Litz cable, comprising a non-layered integrated mesh topology formed by interlacing multiple bundles of independent yarn systems in the same three-dimensional braiding process:

[0009] The conductive region is composed of multiple independent insulated conductive fiber bundles. The conductive fiber bundles extend along a spiral path and periodically change positions within the three-dimensional braid. Within each change pitch, radial and circumferential spatial positions are exchanged to form a statistically equal micro-topology of current paths.

[0010] The magnetically controlled region is composed of magnetic fiber bundles independent of the conductive fiber bundles. The magnetic fiber bundles intersect with the conductive fiber bundles in three-dimensional space and form an array of mechanically interlocked nodes, constructing a continuous three-dimensional magnetic flux topology network that encloses the conductive region.

[0011] The insulating region is composed of independent insulating fibers, which fill the gaps between the conductive fiber bundles and the magnetic fiber bundles.

[0012] The structural region is composed of independent structural fibers, forming a framework that maintains the network topology.

[0013] Among them, the mechanical interlocking nodes enable the magnetic fiber bundles and conductive fiber bundles to be anchored to each other at the microscale, and there are no radially distributed interlayer interfaces between the functional areas.

[0014] Furthermore, the diameter of a single conductive fiber in the conductive fiber bundle is 5 μm to 200 μm, and each bundle contains 3 to 128 conductive fibers, with the surface covered with a polyimide or ceramicized silicone rubber insulating coating with a thickness of 1 μm to 20 μm; the magnetic fiber bundle is a ferrite composite fiber or amorphous soft magnetic fiber with a relative permeability of 10 to 1000 and a volume fraction of 5% to 60%.

[0015] Furthermore, the node density of the mechanical interlocking nodes is 5 to 50 per cubic centimeter; at the mechanical interlocking nodes, the structural fibers pass through the gaps in the conductive fiber bundles at an interlacing angle of 20° to 60°, forming a point-to-line contact or surface-to-surface bonding anchoring relationship with the conductive fiber bundles.

[0016] Secondly, the present invention provides a three-dimensional braided power inductor, comprising a three-dimensional braid having an integrated fiber microstructure:

[0017] The conductive region is formed by multiple bundles of independently insulated conductive fibers arranged according to the Litz principle to form an inductor winding;

[0018] The magnetocontrolled region is composed of magnetic fiber bundles, forming a three-dimensional continuous magnetic circuit that surrounds or penetrates the conductive region.

[0019] In this structure, the magnetic fiber bundles form a continuous topological gradient structure inside the three-dimensional braid. That is, the distribution density of the magnetic fiber bundles changes continuously and gradually along the radial or axial direction, and the fibers continue to extend and intertwine within the gradual change region without forming a physical interface with abrupt changes in magnetic permeability.

[0020] Furthermore, magnetic fiber bundles and conductive fiber bundles form magnetic confinement nodes at their spatial intersections. At the magnetic confinement nodes, the extension path of the magnetic fiber bundle has a spiral encirclement angle of 30° to 80° relative to the axis of the conductive fiber bundle, so that the magnetic fiber bundle forms a physical encirclement path for the alternating magnetic flux generated by the conductive fiber bundle in the local area of ​​the node.

[0021] Furthermore, the magnetocontrol zone includes an E-type magnetic yoke, a central magnetic column, and an air gap; the air gap is formed in the three-dimensional weaving process by a spaced-out weaving method, that is, during weaving, a removable water-soluble polyvinyl alcohol yarn or a removable mandrel is set at the target position of the air gap, and after molding, the spacer is removed to form an air gap with a width of 0.1 mm to 2.0 mm.

[0022] Thirdly, the present invention provides a method for processing the end of a three-dimensional braided Litz yarn, for processing a three-dimensional braided Litz yarn containing insulating fibers and structural fibers, comprising the following steps:

[0023] Insulation removal steps: Remove end insulation using plasma cutting or laser cutting;

[0024] Loosening step: High-frequency mechanical vibration of 15kHz to 40kHz is applied to the exposed ends of the conductive fiber bundle using an ultrasonic vibration unit. The energy of the vibration acts on the micro-weaving nodes between the conductive fiber bundle and the insulating and structural fibers to break the mechanical interlocking topology formed by the three-dimensional weaving process, so that the conductive fiber filaments are released from the weaving mesh and dispersed freely.

[0025] Bundling and pre-compression steps: Arrange the separated conductive fiber bundles in the bundling mold and pre-compress them;

[0026] Welding steps: Solid-state welding of the pre-pressed end preform is performed using ultrasonic welding, laser welding or friction stir welding to form a metallurgical bond between the multiple conductive fiber bundles.

[0027] Furthermore, the terminal connection structure formed by the welding step includes a flat terminal body and an electroplated protective layer covering its surface; the width-to-thickness ratio of the flat terminal body is 3:1 to 20:1, and the volume fraction of conductive fibers is [missing information]. And the contact resistance is less than 0.1mΩ.

[0028] Furthermore, when the three-dimensional braided Litz yarn has hollow cooling channels, a sealing step is also included after the welding step: a sealing colloid is injected into the end of the hollow cooling channel and a vacuum is drawn to -0.1MPa to -0.08MPa to allow the sealing colloid to penetrate and cure, forming a sealed structure integrated with the welded end.

[0029] Fourthly, the present invention provides a method for manufacturing a three-dimensional braided multifunctional Litz cable, comprising the following steps:

[0030] Multiple bundles of independently insulated conductive fibers, independent magnetic fibers, independent insulating fibers, and independent structural fibers are loaded into the corresponding spindles of the three-dimensional braiding machine.

[0031] In the control system of the 3D braiding machine, the routing path of each fiber bundle is set so that the conductive fiber bundles... The weaving angles and pitches from 1mm to 100mm are interwoven and arranged in three-dimensional space;

[0032] The three-dimensional braiding machine is controlled to perform the three-dimensional braiding process. By controlling the movement trajectory of the yarn carrier, mechanical interlocking nodes are formed, and the conductive area, magnetic control area, insulation area and structural area are integrated into one piece.

[0033] The beneficial effects of this invention are as follows: Micro-topology reconstruction: By using "mechanically interlocked nodes" and "non-layered mesh topology", the physical interface of traditional cables is completely eliminated, solving the problems of high interface thermal resistance and interlayer peeling.

[0034] Electromagnetic performance optimization: The Litz transposition path microscopically balances the magnetic flux, significantly reducing high-frequency AC losses; the continuous topological gradient structure of the magnetocontrol zone achieves a smooth transition of magnetic circuit performance, with no stress concentration points.

[0035] Technological innovation: By using "space-occupying weaving" to create air gaps and "ultrasonic breaking nodes" for end treatment, the manufacturing and connection problems of three-dimensional braided structures are specifically solved.

[0036] High reliability: The one-piece molded structure allows the fibers in each functional area to work together to bear the force through interlocking nodes even under extreme bending and vibration environments, greatly improving the cable's lifespan. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic cross-sectional view of the three-dimensional braided multifunctional Litz cable of the present invention;

[0039] Figure 2 This is a topology diagram of the yarn system of the three-dimensional braided multifunctional Litz cable of the present invention;

[0040] Figure 3 Comparison of cross-sections of the three-dimensional braided multifunctional Litz cable with various cross-sectional shapes (circular, flat, square, hollow) according to the present invention;

[0041] Figure 4 This is a three-dimensional unfolded diagram of the Litz transposition pitch of the present invention;

[0042] Figure 5 This is a schematic diagram illustrating an application embodiment of the wireless charging coil of the present invention;

[0043] Figure 6 This is a radial cross-sectional view of the hollow solenoid-shaped three-dimensional braided power inductor of the present invention;

[0044] Figure 7 This is a schematic diagram of the structure of the toroidal three-dimensional braided power inductor of the present invention;

[0045] Figure 8 This is a schematic diagram of the structure of the E-type three-dimensional braided power inductor of the present invention;

[0046] Figure 9 This is a simulation diagram of the magnetic flux path of the three-dimensional braided power inductor of the present invention;

[0047] Figure 10 This is a modified structural diagram of an embodiment of the three-dimensional braided power inductor of the present invention;

[0048] Figure 11 This is a flowchart of the method for processing the ends of braided Litz yarn according to the present invention;

[0049] Figure 12 This is a schematic diagram of the layout of the end-processing device of the present invention;

[0050] Figure 13 This is a schematic diagram of the flat terminal molding structure of the present invention;

[0051] Figure 14 This is a cross-sectional view of the end-gluing seal of the three-dimensional braided Litz yarn with hollow cooling channels according to the present invention;

[0052] Figure 15 This is a modified structural diagram of an embodiment of the present invention.

[0053] 1. Three-dimensional braided Litz wire; 2. Conductive area; 3. Conductive fiber bundle; 4. Magnetron region;

[0054] 5. Magnetic fiber bundle; 6. Insulation area; 7. Insulating fiber; 8. Structural area; 9. Structural fiber; 12. Wireless charging coil; 13. Winding; 14. Magnetic circuit reinforcement layer; 16. Outer yoke; 17. Central magnetic column; 18. Type I yoke; 19. Air gap; 20. Hollow solenoid power inductor; 23. Magnetic flux; 24. Planar spiral inductor; 25. Multilayer stacked inductor; 26. Racetrack-shaped inductor; 27. Type C inductor; 28. Terminal connection structure; 29. ​​Flat terminal body; 30. Electroplated protective layer; 31. Positioning fixture; 32. Plasma cutting device 33. Laser cutting device; 34. Ultrasonic vibration unit; 35. Bundling mold; 36. Hydraulic pre-pressing device; 37. Ultrasonic welding device; 38. Laser welding device; 39. Friction stir welding device; 40. Polishing device; 41. Electroplating device; 43. Hollow cooling channel; 44. Sealing colloid; 45. Online detection and quality traceability unit; 46. Power module interface; 47. Conductive monofilament; 48. Ring terminal with mounting hole; 49. Bending terminal. Detailed Implementation

[0055] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0056] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0057] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0058] Reference Figures 1-15 As one embodiment of the present invention, this embodiment provides a three-dimensional braided multifunctional Litz cable, comprising a non-layered integrated mesh topology formed by interlacing multiple bundles of independent yarn systems in the same three-dimensional braiding process:

[0059] The conductive region is composed of multiple independent insulated conductive fiber bundles. The conductive fiber bundles extend along a spiral path and periodically change positions within the three-dimensional braid. Within each change pitch, radial and circumferential spatial positions are exchanged to form a statistically equal micro-topology of current paths.

[0060] The magnetically controlled region is composed of magnetic fiber bundles independent of the conductive fiber bundles. The magnetic fiber bundles intersect with the conductive fiber bundles in three-dimensional space and form an array of mechanically interlocked nodes, constructing a continuous three-dimensional magnetic flux topology network that encloses the conductive region.

[0061] The insulating region is composed of independent insulating fibers, which fill the gaps between the conductive fiber bundles and the magnetic fiber bundles.

[0062] The structural region is composed of independent structural fibers, forming a framework that maintains the network topology.

[0063] Among them, the mechanical interlocking nodes enable the magnetic fiber bundles and conductive fiber bundles to be anchored to each other at the microscale, and there are no radially distributed interlayer interfaces between the functional areas.

[0064] Reference Figure 1 and Figure 2 This cable differs from traditional layered or post-coated shielding cable structures. Its core feature lies in its non-layered, integrated mesh topology, formed by multiple independent yarn systems interwoven in the same three-dimensional braiding process. This structure breaks down the physical boundaries between functional areas in traditional cables, achieving a high degree of functional integration and deep structural fusion through microscopic fiber interweaving.

[0065] Specifically, the three-dimensional braided multifunctional Litz cable 1 mainly includes four functional zones: conductive zone 2, magnetic control zone 4, insulation zone 6, and structural zone 8. These four functional zones are not spliced ​​together by gluing, welding, or bonding, but rather formed by their independent yarn systems moving synchronously, interlacing, and locking together in three-dimensional space under the operation of a three-dimensional braiding machine, thus forming an inseparable whole.

[0066] First, conductive area 2 is the core current-carrying part of the cable. (Refer to...) Figure 1 and Figure 4 The conductive region 2 is composed of multiple independently insulated conductive fiber bundles 3. In this embodiment, the conductive fiber bundles 3 are preferably made of silver-plated copper fibers or nickel-plated copper fibers, and the diameter of a single conductive fiber is controlled between 10 μm and 80 μm, for example, a single filament with a diameter of 50 μm is selected to ensure effective suppression of the skin effect under high-frequency current. Each conductive fiber bundle 3 contains multiple (e.g., 37) mutually insulated single filaments, and the surface of the single filaments is coated with an insulating coating of polyimide or ceramicized silicone rubber with a thickness of 2 μm to 8 μm.

[0067] In terms of microscopic topology, the conductive fiber bundles 3 are not simply arranged in parallel within the three-dimensional braid, but rather extend along a helical path and undergo periodic repositioning. For example... Figure 4As shown in the three-dimensional unfolded diagram of the Litz transposition pitch, within each transposition pitch L, the conductive fiber bundles 3 undergo a spatial exchange between the radial and circumferential directions. For example, a fiber bundle originally located radially inside the cable cross-section will move to the outside in the next pitch, while a fiber bundle originally located at a certain angle in the circumferential direction will rotate to another angle. This dynamic spatial exchange allows each conductive fiber bundle 3 to share the current equally on a macroscopic level and to form an isotropic current path micro-topology on a microscopic level, thereby balancing the magnetic flux linked by each fiber bundle and significantly reducing AC losses caused by proximity effects.

[0068] Secondly, the magnetron sputtering region 4 is one of the key innovations that distinguishes this invention from existing technologies. The magnetron sputtering region 4 is composed of magnetic fiber bundles 5 independent of the conductive fiber bundles 3. These magnetic fiber bundles 5 are typically made of ferrite composite fibers or amorphous soft magnetic fibers, with a relative permeability of 50 to 500. (Refer to...) Figure 2 The magnetic fiber bundles 5 interweave with the conductive fiber bundles 3 in three-dimensional space. This interweaving is not random, but forms an array of mechanically interlocking nodes. At these nodes, the structural fibers 9 or magnetic fiber bundles 5 pass through the gaps in the conductive fiber bundles 3 at specific angles, thereby anchoring the magnetic fiber bundles 5 and the conductive fiber bundles 3 to each other at a microscale. This unique interlocking structure constructs a continuous three-dimensional magnetic flux topology network that envelops the conductive region 2. When current flows through the conductive region 2, the generated magnetic flux can be effectively constrained and guided by the continuous magnetic circuit formed by the magnetic fiber bundles 5, providing intrinsic electromagnetic shielding without the need for an additional metal shielding layer, thus significantly reducing the weight and rigidity of the cable.

[0069] Furthermore, the insulating region 6 is composed of independent insulating fibers 7. These insulating fibers 7 fill the gaps between the conductive fiber bundles 3 and the magnetic fiber bundles 5, as well as the gaps between the conductive fiber bundles 3. The insulating fibers 7 are preferably polyimide fibers or aramid fibers, and their function is to provide reliable inter-strand or inter-turn electrical isolation to prevent short circuits. Because fiber filling is used instead of traditional integral wrapping, the insulating region 6 is also interwoven and fused with the conductive region 2 and the magnetostrictive region 4, without a smooth separation interface, thereby improving the overall thermal cycling resistance and mechanical fatigue resistance.

[0070] Finally, structural zone 8 is composed of independent structural fibers 9, forming a skeleton that maintains the entire mesh topology. Structural fibers 9 are typically made of high-strength aramid fibers, carbon fibers, or poly(p-phenylene benzodioxazole) (PBO) fibers. Structural fibers 9 are mainly distributed in the outermost layer or key stress nodes of the three-dimensional braided multifunctional Litz cable 1, providing not only the necessary mechanical support and shape retention but also interweaving with fibers from other functional zones, further enhancing the overall structural strength of the cable.

[0071] In this embodiment, the four functional zones are integrally formed in the same three-dimensional braiding process through mechanically interlocking nodes. There are no radially distributed interlayer interfaces between the functional zones, meaning there is no layered structure of "conductor-insulation-shield" as in traditional cables. This non-layered integrated mesh topology completely eliminates the risks of interlayer contact thermal resistance and mechanical slippage, allowing the fibers in each functional zone to work together to maintain stable electrical performance even under severe bending, torsion, or vibration.

[0072] Reference Figure 3 The cross-sectional shape of the three-dimensional braided multifunctional Litz cable 1 in this embodiment is highly flexible. Depending on the application scenario, by adjusting the movement trajectory of the yarn carrier in the control system of the three-dimensional braiding machine, various cross-sectional shapes such as circular, flat, square, polygonal, irregular, or hollow can be manufactured. For example, for applications requiring highly flexible wearable devices, a circular or flat cross-section can be selected; for planar transformer applications requiring increased winding window fill rate, a square or hollow cross-section can be selected.

[0073] As a specific example (refer to) Figure 1 and Figure 2 A circular cross-section three-dimensional braided multifunctional Litz cable was manufactured. A four-step three-dimensional braiding machine was used, loaded with 12 bundles of conductive fibers, each bundle containing 37 silver-plated copper fibers with a diameter of 50μm, and covered with a 3μm thick polyimide insulation layer; several bundles of MnZn-based ferrite composite magnetic fibers were loaded as the magnetocontrol zone; polyimide fibers were loaded as the insulation zone; and aramid fibers were loaded as the structural zone. The braiding angle was set in the control system. The transposition pitch is 5mm. The braiding machine is started, and each yarn carrier moves along a predetermined path, causing the conductive fiber bundle 3 to periodically transpose in three-dimensional space. Simultaneously, the magnetic fiber bundle 5 and structural fiber 9 interweave, forming mechanically interlocked nodes with a node density of approximately 30 nodes / cm³. The resulting cable 1 has an outer diameter of 3.6mm. Testing showed that under 100kHz and 1A current conditions, the AC resistance of this cable is approximately 30% lower than that of a traditional Litz cable of the same cross-section. Furthermore, after 100,000 repeated bending cycles, no peeling occurred in any of the functional areas, demonstrating extremely high reliability.

[0074] In addition, refer to Figure 5This three-dimensional braided multifunctional Litz cable 1 can also be applied to the field of wireless charging. By winding the cable 1 onto a planar mold to form a planar helical winding 13, and then using a magnetic fiber bundle 5 to form a magnetic circuit reinforcement layer 14 (which can be integrally molded or covered by secondary braiding), the transmission efficiency and anti-interference capability of the wireless charging coil 12 can be significantly improved. Due to the cable 1's excellent flexibility and integrated intrinsic shielding, the wireless charging coil 12 can be directly integrated into curved or flexible structures such as smartwatch straps and automotive interiors, solving the problem of limited installation of traditional rigid coils.

[0075] In summary, this invention constructs a Litz cable with a reconstructed micro-topology through a three-dimensional braiding process, and integrates the four functional zones of conductivity, magnetic control, insulation, and structure by utilizing mechanical interlocking nodes. This effectively solves the problems of high thermal resistance, high high-frequency loss, poor flexibility, and low reliability of the layered structure in the prior art.

[0076] Furthermore, the diameter of a single conductive fiber in the conductive fiber bundle is 5 μm to 200 μm, and each bundle contains 3 to 128 conductive fibers, with the surface covered with a polyimide or ceramicized silicone rubber insulating coating with a thickness of 1 μm to 20 μm; the magnetic fiber bundle is a ferrite composite fiber or amorphous soft magnetic fiber with a relative permeability of 10 to 1000 and a volume fraction of 5% to 60%.

[0077] In this embodiment, refer to Figure 1 and Figure 2 As shown, the conductive fiber bundle 3 employs a miniaturized design, with the diameter of a single conductive fiber preferably set to 10μm to 80μm. This narrow diameter design is significantly smaller than the skin depth under high-frequency current, effectively suppressing the skin effect and reducing AC resistance. Each conductive fiber bundle 3 consists of 3 to 128 such independently insulated monofilaments. This configuration ensures current transmission capability while giving the cable excellent flexibility, facilitating cabling in complex spaces.

[0078] To ensure electrical safety in high-density braiding environments, it is preferable that each conductive fiber is coated with an insulating coating with a thickness of 2μm to 8μm. This coating material is selected from polyimide or ceramicized silicone rubber, which possess excellent high-temperature resistance and insulation properties, providing reliable electrical isolation even in minute gaps.

[0079] Meanwhile, the magnetic fiber bundle 5 constituting the magnetron region 4 is made of ferrite composite fibers or amorphous soft magnetic fibers, possessing soft magnetic properties with a relative permeability of 50 to 500. In the micro-topology design, the proportion (volume fraction) of the magnetic fiber bundle 5 in the overall cable volume is strictly controlled between 15% and 40%. This parameter range is optimized: if the volume fraction is below 15%, an effective three-dimensional magnetic flux network cannot be formed to provide intrinsic shielding; if it is above 40%, the proportion of conductive fibers will be reduced and the cable stiffness will be significantly increased. Through the precise limitation of the above materials and parameters, the magnetic fiber bundle can construct a continuous and efficient magnetic flux path, achieving excellent electromagnetic compatibility performance, while maintaining the overall lightweight and high flexibility of the cable.

[0080] Furthermore, the node density of the mechanical interlocking nodes is 5 to 50 per cubic centimeter; at the mechanical interlocking nodes, the structural fibers are... The interlacing angle passes through the gaps in the conductive fiber bundles, forming a point-to-line contact or surface-to-surface bonding anchoring relationship with the conductive fiber bundles.

[0081] Reference Figure 2 In this embodiment, the microstructure topology construction of the three-dimensional braided multifunctional Litz cable is optimized by focusing on the mechanical interlocking node characteristics between the fiber systems to ensure that the cable has excellent structural stability while possessing high flexibility.

[0082] Specifically, by precisely controlling the movement trajectory of the yarn carrier and the weaving rhythm of the 3D braiding machine, the node density of the mechanical interlocking nodes is set to 5 to 50 per cubic centimeter. This density range is optimized; if the node density is below 5 nodes / cm³, the anchoring effect is insufficient, making it difficult to effectively restrain the relative slippage between fibers; if the density is above 50 nodes / cm³, the nodes will be too dense, increasing cable stiffness and potentially damaging the conductive fiber filaments. Within this density range, the cable can maintain good flexibility while possessing sufficient tensile and torsional resistance.

[0083] At the microstructure level, the formation of the mechanically interlocking nodes depends on the spatial interpenetration strategy of the structural fibers 9. The structural fibers 9... The interlacing angle passes through the gaps in the conductive fiber bundle 3. This specific angle range is crucial: if the interlacing angle is less than 20°, the structural fibers cannot form a stable interlocking force on the surface of the conductive fiber bundle, and are prone to loosening; if the interlacing angle is greater than 60°, it will generate excessive lateral compressive stress on the conductive fiber monofilaments, increasing the risk of breakage. Within the preferred angle range, a tight physical constraint is formed between the structural fiber 9 and the conductive fiber bundle 3, specifically manifested as a point-to-line contact or surface-to-surface bonding anchoring relationship. This micro-scale anchoring not only locks the magnetic fiber bundle 5 and the conductive fiber bundle 3 together, preventing relative slippage and delamination during dynamic bending or stretching, but also enables each functional area to deform collaboratively under stress, greatly improving the overall mechanical strength and long-term service reliability of the cable.

[0084] Furthermore, such as Figure 4 As shown, a three-dimensional braided multifunctional Litz cable 1 is cut open along its axial direction, revealing the Litz transposition path of the conductive fiber bundles 3 in three-dimensional space. Conductive fiber bundles 3A, 3B, 3C, and 3D are four independently insulated conductive fiber bundles that sequentially exchange spatial positions within the axial length L (i.e., the transposition pitch): 3A transposes from the radially outer side to the radially inner side, 3B transposes from the radially inner side to the radially outer side, and 3C and 3D are transposed in a staggered manner in the circumferential direction. Each conductive fiber bundle passes through different radial and angular positions on the cable cross-section macroscopically, thereby equalizing the magnetic flux linked by each conductive fiber bundle in time and suppressing additional losses caused by proximity effects. Magnetic fiber bundle 5 extends continuously along the axial direction, intertwining with conductive fiber bundle 3 at the transposition nodes but without electrical contact, and is isolated by insulating fiber 7.

[0085] Secondly, the present invention provides a three-dimensional braided power inductor, comprising a three-dimensional braid having an integrated fiber microstructure:

[0086] The conductive region is formed by multiple bundles of independently insulated conductive fibers arranged according to the Litz principle to form an inductor winding;

[0087] The magnetocontrolled region is composed of magnetic fiber bundles, forming a three-dimensional continuous magnetic circuit that surrounds or penetrates the conductive region.

[0088] In this structure, the magnetic fiber bundles form a continuous topological gradient structure inside the three-dimensional braid. That is, the distribution density of the magnetic fiber bundles changes continuously and gradually along the radial or axial direction, and the fibers continue to extend and intertwine within the gradual change region without forming a physical interface with abrupt changes in magnetic permeability.

[0089] This embodiment provides a three-dimensional braided power inductor. The core innovation of this power inductor lies in abandoning the traditional "winding + assembling magnetic core" manufacturing method, and instead directly forming it through a three-dimensional braiding process to obtain a three-dimensional braided body with a unique microscopic topological structure. (Refer to...) Figure 6 , Figure 7 and Figure 9 This three-dimensional braided power inductor is made entirely of fiber material, with each functional component deeply interwoven at the microscale to form an inseparable whole.

[0090] Specifically, this three-dimensional braided structure mainly consists of two core functional areas: a conductive region 2 and a magnetocontrollable region 4. Structurally, these two areas are physically separated by an insulating region 6, but they are manufactured simultaneously. The conductive region 2 is the energy conversion core of the inductor and is composed of multiple independently insulated bundles of conductive fibers 3. (Refer to...) Figure 6 These conductive fiber bundles 3 are not simply spirally wound, but are transposed in three-dimensional space strictly according to the Litz principle to form an inductor winding. This transposition structure ensures that each conductive fiber is evenly placed in a magnetic field environment in three-dimensional space, effectively canceling the proximity effect and skin effect under high-frequency current, and significantly reducing the AC resistance of the winding.

[0091] The magnetically controlled region 4 is the key difference between this embodiment and the prior art. (Refer to...) Figure 6 and Figure 9 The magnetocontrol zone 4 is composed of magnetic fiber bundles 5, which are arranged according to a preset path during the three-dimensional weaving process to form a three-dimensional continuous magnetic circuit that surrounds or penetrates the conductive zone 2. When current is passed through the conductive zone 2, the generated alternating magnetic flux 23 will be mainly confined within this magnetic circuit, thereby achieving efficient energy storage and conversion.

[0092] A significant feature of this embodiment is that the magnetic fiber bundles 5 in the magnetocontrol zone 4 form a continuous topological gradient structure within the three-dimensional braid. (Refer to...) Figure 6 As shown in the radial cross-sectional view, this gradient structure is characterized by a continuous, gradual change in the distribution density of the magnetic fiber bundles 5 along the radial or axial direction. For example, in an embodiment of the hollow solenoid power inductor 20, the distribution density of the magnetic fiber bundles 5 is higher, reaching over 65%, in the inner core region near the axis, to provide a high permeability path and ensure smooth passage of the magnetic flux 23; while in the outer yoke region 16 away from the axis, the distribution density of the magnetic fiber bundles 5 gradually decreases to 40% or lower.

[0093] This continuous gradient is achieved through precise programming of the control system of the three-dimensional braiding machine. During the braiding process, the control system, based on a digital model, instructs the yarn carrier carrying the magnetic fiber bundle 5 to "cut in" or "cut out" the braiding path segment by segment at specific axial or radial positions. This variable spindle braiding method ensures a smooth transition in the magnetic fiber content per unit volume, rather than a step-like abrupt change.

[0094] Reference Figure 9The simulation diagram of the magnetic flux path shows that, within the gradient region, the magnetic fiber bundle 5 maintains continuous extension and interweaving without any physical interruption or splicing of the material. Therefore, no physical interface with abrupt changes in magnetic permeability is formed within the three-dimensional braid. This means that when the magnetic flux 23 propagates within the magnetic circuit, it will not encounter abrupt changes in magnetic reluctance or stress concentration points at the joints of traditional spliced ​​magnetic cores, thus significantly reducing eddy current losses and hysteresis losses. Simultaneously, this gradient distribution achieves optimal material configuration, significantly reducing the amount of magnetic fiber used while ensuring inductance, thus achieving device lightweighting. Testing shows that the power inductor using this structure achieves a quality factor Q of over 80 at 1MHz and maintains excellent inductance stability even under bending conditions.

[0095] Furthermore, magnetic fiber bundles and conductive fiber bundles form magnetic confinement nodes at their spatial intersections. At the magnetic confinement nodes, the extension path of the magnetic fiber bundle has a spiral encirclement angle of 30° to 80° relative to the axis of the conductive fiber bundle, so that the magnetic fiber bundle forms a physical encirclement path for the alternating magnetic flux generated by the conductive fiber bundle in the local area of ​​the node.

[0096] Reference Figure 2 and Figure 6 In the three-dimensional braided power inductor of this embodiment, the microstructure design inside the three-dimensional braid further optimizes the coupling effect between the magnetic circuit and the electrical circuit. Specifically, the intersection of the magnetic fiber bundle 5 and the conductive fiber bundle 3 in three-dimensional space is not a simple geometric intersection, but is deliberately designed to form "magnetically confined nodes" with specific functions. These nodes are an important part of the micro-topology and directly determine the inductor's magnetic flux confinement capability and high-frequency performance.

[0097] In terms of microstructure, at each magnetic confinement node, the extension path of the magnetic fiber bundle 5 exhibits a specific spatial orientation relative to the axis of the conductive fiber bundle 3. Specifically, this path forms a helical encirclement angle of 30° to 80° with respect to the axis. This angle range has been rigorously calculated and verified: if the angle is less than 30°, the magnetic fiber bundle 5 tends to be parallel to the conductive fiber bundle 3, making it difficult to effectively encircle the magnetic field; if the angle is greater than 80°, although the encirclement is theoretically enhanced, it is difficult to achieve in the three-dimensional weaving process and is prone to damaging the fibers. By controlling the helical encirclement angle between 30° and 80°, the magnetic fiber bundle 5 can physically encircle the conductive fiber bundle 3 with an optimal winding tendency at the node locality.

[0098] This microscopic helical winding structure allows the magnetic fiber bundle 5 to locally construct a physical encirclement path for the alternating magnetic flux generated by the conductive fiber bundle 3 at the nodes. When alternating current flows through the conductive fiber bundle 3, the excited magnetic flux lines are captured and guided at the microscopic level by the adjacent magnetic fiber bundle 5 through these physical encirclement paths, thereby greatly constraining the divergence of the magnetic field and significantly reducing leakage flux. This local magnetic confinement, combined with the macroscopic continuous magnetic circuit, enables the three-dimensional braided power inductor to effectively suppress high-frequency losses and electromagnetic interference while increasing inductance density, achieving excellent power conversion efficiency.

[0099] Furthermore, the magnetocontrol zone includes an E-type magnetic yoke, a central magnetic column, and an air gap; the air gap is formed in the three-dimensional weaving process by a spaced-out weaving method, that is, during weaving, a removable water-soluble polyvinyl alcohol yarn or a removable mandrel is set at the target position of the air gap, and after molding, the spacer is removed to form an air gap with a width of 0.1 mm to 2.0 mm.

[0100] Reference Figure 8 This embodiment provides a specific manufacturing structure for an E-type three-dimensional braided power inductor, focusing on the unique molding process of the air gap 19 in its magnetron control region 4. The inductor is integrally molded using a three-dimensional braiding process, wherein the magnetron control region 4 is constructed as an E-type magnetic yoke structure, specifically including a central magnetic post 17, an I-type magnetic yoke 18, and an air gap 19 located between the two.

[0101] In traditional manufacturing, air gaps usually require cutting or splicing the formed magnetic core, which can easily lead to burrs or unstable magnetic resistance. In this embodiment, however, the air gap 19 is formed directly in the three-dimensional weaving process through a "placement weaving" method, ensuring the continuity of the magnetic fiber bundle 5 when it passes around the air gap.

[0102] In practice, during the weaving process of the braiding machine, the operator pre-sets a removable spacer at a predetermined air gap target position—between the central magnetic column 17 and the type I magnetic yoke 18. This spacer is preferably made of water-soluble polyvinyl alcohol (PVA) yarn, but a removable mandrel of a specific material can also be used. As the weaving process proceeds, the conductive fiber bundle 3 and the magnetic fiber bundle 5 intertwine and wrap around the spacer, occupying the space that would otherwise be filled with magnetic fibers, thus reserving a gap inside the braided body.

[0103] After the three-dimensional braided body is woven as a whole, a post-processing step is performed. If water-soluble polyvinyl alcohol yarn is used, it is completely dissolved and removed by water-soluble cleaning; if a removable mandrel is used, it is carefully pulled out. After the placeholder is removed, a physical air gap 19 is formed in the originally occupied position.

[0104] The air gap 19 produced by this process has extremely high precision, which can be controlled between 0.1mm and 2.0mm. By adjusting the diameter of the occupier yarn or the thickness of the mandrel, the air gap width can be precisely set, thereby effectively adjusting the saturation characteristics and inductance of the inductor. Moreover, the air gap surface is smooth, requiring no additional machining, thus ensuring the integrity of the magnetic circuit.

[0105] Furthermore, such as Figure 10 As shown, the three-dimensional braided power inductor of this invention can directly obtain various deformable structures by adjusting the braiding model, including but not limited to:

[0106] Planar spiral inductor 24: Conductive area 2 is woven along a planar spiral path, and magnetic control area 4 is laid on the upper and lower sides of conductive area 2 to form a flat magnetic circuit, which is suitable for ultra-thin power modules;

[0107] Multilayer stacked inductor 25: The upper and lower solenoid-shaped conductive regions 2 are separated and magnetically coupled by the interlayer magnetocontrol region 4 to form a high inductance density three-dimensional integrated inductor.

[0108] Racetrack-shaped inductor 26: Conductive area 2 is wound along elliptical / racetrack-shaped magnetized area 4, suitable for narrow spaces;

[0109] C-type inductor 27: The magnetized region 4 is formed into a C-type magnetic yoke, and the conductive region 2 is wound on a C-type open column. The air gap is adjustable and it is suitable for high-current energy storage scenarios.

[0110] Thirdly, the present invention provides a method for processing the end of a three-dimensional braided Litz yarn, for processing a three-dimensional braided Litz yarn containing insulating fibers and structural fibers, comprising the following steps:

[0111] S1. Insulation removal step: Remove end insulation by plasma cutting or laser cutting;

[0112] In this embodiment, the insulation removal step S1 corresponds to... Figure 11The insulation removal step in the illustrated process aims to precisely remove the insulation coating at the end region without damaging the internal conductor. Given the dense interlocking fiber structure of the 3D braided Litz cable 1, traditional mechanical stripping easily leads to broken conductive fiber bundles 3 or damage to the structural integrity. Therefore, a non-contact thermal processing method is preferred in this step. Specifically, after fixing the cable end, a plasma cutting device 32 or a laser cutting device 33 is used to irradiate the end. The high-energy beam can quickly vaporize or peel off the surface insulation fibers 7, clearly exposing the ends of the deeply embedded conductive fiber bundles 3. Regarding process parameter control, the insulation removal length L is set to 3mm to 20mm, preferably 5mm to 10mm; if laser cutting is used, the power is controlled between 50W and 500W; if plasma cutting is used, the power is adjusted to 200W to 2000W. This processing method produces a clean cut, is highly efficient, and effectively avoids damage to the micro-braided nodes caused by mechanical stress.

[0113] S2, Loosening Step: High-frequency mechanical vibration of 15kHz to 40kHz is applied to the exposed ends of the conductive fiber bundle using an ultrasonic vibration unit. The energy of the vibration acts on the micro-weaving nodes between the conductive fiber bundle and the insulating and structural fibers to destroy the mechanical interlocking topology formed by the three-dimensional weaving process, so that the conductive fiber filaments are released from the weaving mesh and dispersed freely.

[0114] This step is specifically as follows: Refer to Figure 11 and Figure 12 This embodiment details the "loosening step" in the three-dimensional braided Litz wire end treatment method. This step is crucial for connecting insulation removal and subsequent bundle pre-compression. Its core purpose is to overcome the fiber separation problem caused by the unique mechanical interlocking structure of the three-dimensional braid, releasing the exposed conductive fiber bundles from the dense braided mesh, thus preparing for the formation of low-resistance metallurgical bonding terminals. This step can be further broken down into the following three sub-steps:

[0115] Step 1: Precise positioning and vibration parameter initialization

[0116] After the insulation removal step is completed, the conductive fiber bundles 3 are exposed at the end of the 3D braided Litz wire 1, but the fibers are still tightly wrapped and mechanically locked by the insulating fibers 7 and structural fibers 9. First, the cable end is moved to the working area of ​​the ultrasonic vibration unit 34. The cable is fixed using a high-precision positioning clamp 31 to ensure that the end protrusion length is consistent and the axis is perpendicular or aligned with the vibrating head at a specific angle. Next, the vibration parameters are initialized in the control system of the ultrasonic vibration unit 34 according to the number of strands, the diameter of the single filament, and the material of the insulating coating of the conductive fiber bundle 3. The vibration frequency is set between 15kHz and 40kHz. Generally, a higher frequency (such as 35kHz) is selected for thinner or harder coatings, while a lower frequency (such as 20kHz) is selected for thicker fiber bundles to excite the best energy coupling efficiency. At the same time, the vibration amplitude is adjusted within the range of 5μm to 50μm to ensure that sufficient mechanical energy is provided to break the interlocking nodes without instantaneously breaking the conductive single filaments. At this stage, it is necessary to confirm that the relative positions of the vibrating head and the end are in the optimal energy transfer range, usually in a state of slight contact or close-range radiation, in order to prepare for the subsequent energy burst.

[0117] Step 2: High-frequency energy coupling and microscopic topological dissociation

[0118] The ultrasonic vibration unit 34 is activated to apply high-frequency mechanical vibration for a preset duration (typically 100ms to 3s) to the end of the conductive fiber bundle 3. During this process, vibration energy is efficiently coupled into the fiber bundle through the vibrating head. Due to the complex "mechanical interlocking nodes" formed by the three-dimensional weaving process at the microscopic level, where the structural fibers 9 pass through the gaps in the conductive fiber bundle 3 at an interlacing angle of 20° to 60°, forming point-to-line contact or surface-to-surface bonding, this structure exhibits extremely high tensile strength and structural stability at the macroscopic level. However, under the high-frequency reciprocating impact of the ultrasonic waves, this interlocking relationship is broken. The vibration energy is converted into high-frequency friction and micro-impact forces at the microscopic nodes, causing fatigue fracture at the anchoring contact surfaces between the insulating fibers 7 and structural fibers 9 and the conductive fiber bundle 3. This physical action destroys the mechanical interlocking topology constructed by the three-dimensional weaving process, causing the originally tightly bound conductive fiber bundle 3 to loosen. In addition, the high-frequency vibration can also shatter the fine insulating enamel residue adhering to the surface of the conductive fibers, further cleaning the surface of the monofilaments. As the vibration continues, the originally bundled conductive fiber bundles begin to decompose, and multiple bundles of conductive fibers and conductive monofilaments 47 within the bundles separate from the woven mesh, exhibiting a tendency to disperse freely.

[0119] Step 3: Decentralized cleaning and pretreatment status confirmation

[0120] Immediately after the ultrasonic vibration stops, the ends are subjected to auxiliary dispersion and cleaning. At this point, although the interlocking between the conductive fiber bundle 3 and the structural fiber 9 has been broken, electrostatic adsorption or slight mechanical entanglement may still exist between the fibers. During operation, an inert gas (such as nitrogen) or compressed air can be used to directionally blow away the ends, using the airflow to remove the shattered insulating dust, loose insulating fiber fragments, and structural fiber residue from the conductive fiber bundle. This step not only cleans the end face but also assists in further dispersing the conductive monofilaments, making them completely fluffy and non-adhesive. Finally, the end condition is checked by visual inspection or automatic sensors to confirm that the conductive fiber bundle 3 has been completely dissociated and freely dispersed, and that the surface of the monofilaments is smooth and free of coverings. At this point, the end shape should resemble a fiber brush, with each conductive monofilament having the ability to move freely, creating the necessary physical conditions for the next step of entering the bundling mold 35 for rearrangement and pre-compression, ensuring maximum contact area during subsequent welding.

[0121] S3. Bundling and Pre-compression Steps: Arrange the separated conductive fiber bundles in the bundling mold and pre-compress them;

[0122] This step specifically involves: Step 1: Mold selection and fiber bundling.

[0123] The conductive fiber bundles 3, loosened by ultrasonic vibration, and their internal monofilaments are transferred to the bundling process. Based on the design requirements of the final terminal connection structure 28, a bundling mold 35 with a specific cavity cross-section is selected. The cavity cross-section of the bundling mold 35 is designed to be rectangular, arc-shaped, trapezoidal, or irregularly shaped, with dimensions precisely matching the width and thickness of the target flat terminal body 29. During operation, a wire feeding mechanism or robotic arm guides and fills the loosely dispersed conductive fiber bundles 3 into the cavity of the bundling mold 35. In this process, mechanical combing or vibration assistance ensures that the conductive fibers are evenly distributed within the mold, avoiding local stacking or voids, allowing the multiple conductive fiber bundles 3 to be rearranged and combined according to a preset geometric shape, initially forming a fiber assembly consistent with the terminal shape.

[0124] Step 2: Hydraulic densification pre-compression molding

[0125] After the fiber bundles fill the cavity of the bundling mold 35, the hydraulic pre-compression device 36 is activated to apply high pressure to the fiber assembly within the cavity. The hydraulic system drives the pressure head to move perpendicular to the cable axis, compressing the arranged conductive fiber bundles 3. The pre-compression pressure is set to 2 MPa to 30 MPa, preferably within the range of 5 MPa to 15 MPa. This high-intensity pressure forces plastic deformation and close contact between the conductive fiber bundles 3 and between the conductive monofilaments 47, significantly squeezing out residual air in the fiber gaps and significantly increasing the fiber volume fraction. Simultaneously, this pressure is maintained for a holding period controlled between 100 ms and 5 s to ensure that the fibers fully creep and lock in position under high stress, eliminating the tendency for internal stress rebound.

[0126] Step 3: Shaping and demolding of the end preform

[0127] After the pressure holding period, the hydraulic pre-compression device 36 is depressurized and reset, and the formed end preform is removed. At this point, the originally loose fiber bundles have been compacted into a geometrically regular, dense solid block structure, i.e., the end preform. This preform has an extremely high conductive fiber volume fraction, reaching 50% to 70%, and a smooth, burr-free surface. This dense preform provides an ideal contact interface for subsequent solid-state welding, ensuring efficient transfer of welding energy and uniform metallurgical bonding, thereby ensuring that the final terminal connection structure has low contact resistance and high mechanical strength.

[0128] S4. Welding steps: Solid-state welding of the pre-pressed end preform is carried out by ultrasonic welding, laser welding or friction stir welding to form a metallurgical bond between multiple conductive fiber bundles.

[0129] This step is specifically as follows: Step 1: Prefabricated body positioning and clamping

[0130] The dense end preform formed through the bundling and pre-compression steps is removed from the bundling mold 35 and precisely transferred to the welding station. The end preform is rigidly fixed using a high-precision positioning fixture 31 to ensure that its positional deviation is within the allowable tolerance range and to maintain a predetermined perpendicular or parallel angle relationship between the surface to be welded and the welding actuator (such as an ultrasonic welding head, laser focusing lens, or stirring head), creating stable contact or irradiation conditions for energy input.

[0131] Step 2: Perform solid-state welding according to process requirements

[0132] Based on the size and material properties of the terminals, select one of the following methods for processing the preform: ultrasonic welding, laser welding, or friction stir welding. The specific execution parameters are as follows:

[0133] If an ultrasonic welding device 37 is used: Start the ultrasonic generator, set the frequency to 15kHz to 40kHz (preferably 25kHz), and apply a welding pressure of 0.5MPa to 10MPa to the preform for 200ms to 5s. The frictional heat generated by the high-frequency vibration causes the conductive fibers on the contact surface to undergo plastic deformation, achieving solid metallurgical bonding.

[0134] If using laser welding equipment 38: Select a fiber laser or disk laser, adjust the laser power to 100W to 2000W, and control the spot diameter to 0.1mm to 1.0mm. Under an argon or nitrogen protective atmosphere, control the welding speed to 50mm / s to 500mm / s to scan the surface of the preform. The high-energy laser beam causes the conductive fiber surface to melt instantaneously and fuse together after cooling.

[0135] If friction stir welding device 39 is used: a high-speed rotating stirring head is inserted into the preform at a speed of 500 rpm to 5000 rpm, applying a downward pressure of 0.5 kN to 10 kN, and moving along the welding path at a speed of 0.1 mm / s to 5 mm / s. The frictional heat between the stirring head and the fiber is used to bring the material into a thermoplastic state, and solid-phase bonding is achieved under the forging action of the stirring head.

[0136] Step 3: Metallurgical bonding formation and cooling / settling

[0137] After the aforementioned welding energy input is completed, the physical interfaces between the multiple conductive fiber bundles 3 disappear, the contact resistance is significantly reduced, and a dense metallurgical bond structure is formed through atomic diffusion or recrystallization mechanisms. Energy input is stopped, and the area to be welded is allowed to cool naturally or rapidly through an auxiliary cooling medium, ultimately forming a compact, highly conductive flat terminal body 29, providing a solid substrate for subsequent polishing and electroplating processes.

[0138] Furthermore, the terminal connection structure formed by the welding step includes a flat terminal body and an electroplated protective layer covering its surface; the width-to-thickness ratio of the flat terminal body is 3:1 to 20:1, the volume fraction of conductive fibers is 50% to 70%, and the contact resistance is less than 0.1mΩ.

[0139] Reference Figure 13 The terminal connection structure 28 formed after the welding step mainly consists of a flat terminal body 29 and an electroplated protective layer 30 covering its surface. The flat terminal body 29 is a dense solid formed by metallurgically bonding multiple bundles of conductive fibers 3 through a solid-state welding process. Its morphological characteristic is that the width-to-thickness ratio is strictly controlled between 3:1 and 20:1. This flattened design can effectively improve the connection density of the power module interface 46. In terms of internal microstructure, through the synergistic effect of bundle pre-compression and welding processes, the volume fraction of conductive fibers in the flat terminal body 29 is optimized to... This ensures excellent current transmission capability. Simultaneously, the terminal connection structure exhibits superior electrical performance, with a contact resistance of less than 0.1mΩ, significantly reducing energy loss at the connection point. The electroplated protective layer 30 further enhances its resistance to environmental corrosion.

[0140] Furthermore, when the three-dimensional braided Litz yarn has hollow cooling channels, a sealing step is also included after the welding step: a sealing colloid is injected into the end of the hollow cooling channel and a vacuum is drawn to -0.1MPa to -0.08MPa to allow the sealing colloid to penetrate and cure, forming a sealed structure integrated with the welded end.

[0141] Reference Figure 14 For the three-dimensional braided Litz cable 1 with an integrated hollow cooling channel 43, a sealing step is required after the welding process to ensure the sealing of the cooling medium. Specifically, a specially formulated sealing colloid 44 is first quantitatively injected into the end region of the hollow cooling channel 43 using a precision dispensing device. Subsequently, a vacuum is applied to the end sealing area to reduce the internal pressure and maintain it stably at a negative pressure of -0.1 MPa to -0.08 MPa. Under this high negative pressure environment, the sealing colloid 44 utilizes the internal and external pressure difference to forcefully penetrate into the fiber weave gaps and pores of the three-dimensional braid, eliminating air bubbles and filling microscopic voids. After sufficient penetration, the colloid is cured by ultraviolet light or heat to set, ultimately forming a seamless sealing structure that connects with the flat terminal body 29 and the cable body, achieving both electrical insulation and fluid sealing at the end.

[0142] Fourthly, the present invention provides a method for manufacturing a three-dimensional braided multifunctional Litz cable, comprising the following steps:

[0143] Multiple bundles of independently insulated conductive fibers, independent magnetic fibers, independent insulating fibers, and independent structural fibers are loaded into the corresponding spindles of the three-dimensional braiding machine.

[0144] This step specifically involves: Step 1: Multimodal fiber pretreatment and tension adaptive calibration.

[0145] First, four independent yarn feeding channels are established, corresponding to conductive fiber bundle 3, magnetic fiber bundle 5, insulating fiber 7, and structural fiber 9, respectively. Given the significant differences in the physical properties of the four types of fibers, an intelligent tension adaptive system is used for pretreatment in this step. Conductive fiber bundle 3 is loaded onto a low-friction yarn bobbin with a protective surface coating, and the initial tension is set to 0.5N to 2N to prevent resistivity changes or insulation layer damage due to excessive stretching during unwinding. For the more brittle magnetic fiber bundle 5, an active servo tension control bobbin is used, adjusting the unwinding speed through real-time feedback to ensure tension fluctuations are controlled within ±0.1N, avoiding yarn breakage. Simultaneously, insulating fiber 7 and structural fiber 9 are preheated and subjected to static elimination treatment, and their tensions are set to preset weaving stability values. Through this step, all four types of fibers reach their optimal mechanical state before entering the weaving area, ensuring the smoothness of the subsequent weaving process.

[0146] Step 2: Heterogeneous ingot space mapping based on topological structure

[0147] Utilizing the digital control system of a 3D braiding machine, spatial mapping and loading planning of heterogeneous spindle positions are executed based on a pre-set Litz cable internal topology model. This step breaks away from the traditional random loading mode, strategically allocating different fiber bundles to specific layers and tracks of the braiding machine's yarn carrier. Specifically, magnetic fiber bundle 5 is preferentially loaded onto the inner track of the yarn carrier to construct the magnetically controlled area of ​​the cable core; conductive fiber bundle 3 is loaded onto the middle track and arranged alternately according to the Litz transposition rule; insulating fiber 7 and structural fiber 9 are loaded onto the outer track to construct the external mechanical skeleton and electrical isolation layer. Through this precise regional mapping, the physical position of the yarn carrier directly corresponds to the functional partitioning of the cable cross-section, laying the hardware foundation for achieving "one-step" braiding of complex structures.

[0148] Step 3: Dynamic Balanced Loading and Full-Path Alignment Integration

[0149] After completing tension calibration and position planning, physical loading and end-to-end integration are performed. Spindles loaded with the four types of fibers are installed into their corresponding positions on the 3D braiding machine, and the threading path of each fiber is verified using a machine vision-assisted system. The key to this step is "dynamic balance," which involves adjusting the damping coefficient inside the spindle holder to ensure a dynamic balance between the centrifugal and centripetal forces of the inner, middle, and outer layers of fibers during movement, preventing braiding misalignment caused by differences in fiber density. Finally, the braiding machine is started for a low-speed idle test run, using high-precision sensors to monitor the intersection angle and tension fluctuations of each fiber bundle. Once everything is confirmed to be correct, the spindle positions are locked, completing the loading and integration of the entire system.

[0150] In the control system of the three-dimensional braiding machine, the routing path of each fiber bundle is set so that the conductive fiber bundles are interwoven and arranged in three-dimensional space with a braiding angle of 20° to 75° and a pitch of 1mm to 100mm.

[0151] The specific steps are as follows: Step 1: Digital modeling of the topology path. A Litz transposition digital twin model of the conductive fiber bundle 3 is constructed in the control system. The rotation vector of the fiber bundle in three-dimensional space is preset according to the magnetic flux constraint requirements, and the phase angle of the fiber bundle when passing through the magnetocontrol zone 4 is locked to provide a spatial reference for subsequent motion planning.

[0152] Step 2: Multi-axis nonlinear trajectory calculation. Input the weaving angle from 20° to 75° and the pitch target parameters from 1mm to 100mm. The system calculates the nonlinear motion path of the yarn carrier in the polar coordinate system based on the four-axis linkage algorithm, and automatically generates the differential speed drive command for each spindle to ensure that multiple bundles of conductive fibers achieve precise engagement at the spatial intersection point.

[0153] Step 3: Virtual Simulation and Adaptive Compensation. The trajectory simulation program is run to detect potential interference. Once confirmed to be correct, closed-loop feedback is initiated to monitor the synchronization rate between the traction speed and the spindle speed in real time. The motion deviation is dynamically corrected through a PID algorithm to ensure that the actual weaving path strictly conforms to the set trajectory.

[0154] The three-dimensional braiding machine is controlled to perform the three-dimensional braiding process. By controlling the movement trajectory of the yarn carrier, mechanical interlocking nodes are formed, and the conductive area, magnetic control area, insulation area and structural area are integrated into one piece.

[0155] This step specifically involves: Step 1: Spatiotemporal Coordinated Initiation of Multiphase Yarn Carrier Weaving. The three-dimensional weaving machine is started, and the control system drives hundreds of yarn carriers to perform complex spatial movements based on a preset topological model. Unlike traditional plain weaving, this step controls the phase difference between the weft insertion and warp feeding of the yarn carriers, causing the inner layer of magnetic and conductive fiber bundles to first undergo initial spatial entanglement, followed by the outer layer of insulating and structural fiber bundles. Through precise time difference control, it is ensured that the four types of fibers begin three-dimensional helical motion the instant of contact, establishing an axially continuous three-dimensional weaving skeleton.

[0156] Step Two: Dynamic Trajectory Tracking and Physical Interlocking of Nodes. During continuous weaving, the control system tracks the three-dimensional coordinates of each yarn carrier in real time. When the magnetic fiber bundle crosses the axis of the conductive fiber bundle, the system fine-tunes the angular velocity of the yarn carrier, forcing the magnetic fiber bundle to press against the conductive fiber bundle under high tension, and guiding the structural fiber bundles to intersect and converge from a vertical direction. This multi-dimensional forced correction motion causes the fibers to undergo intense microscopic plastic deformation and compression at the intersection point, thus forming countless irreversible "mechanically interlocked nodes" in space, binding the fiber bundles with different functions together like molecular chains.

[0157] Step 3: Variable Density Continuous Integrated Braiding. With the constant tension output of the traction mechanism, the braiding process enters a stable, integrated molding stage. The system dynamically adjusts the braiding angle and pitch according to the functional requirements of the cable's axial position, achieving differentiated density control for the conductive, magnetically controlled, insulating, and structural zones. Through this continuous braiding action, the four functional zones are not pieced together in segments, but rather seamlessly connected and synchronously extended under the action of molecular-level interlocking nodes, ultimately producing a three-dimensional braided Litz wire with complete electrical and magnetic circuit properties, realizing the integrated manufacturing of the composite structure.

[0158] Example:

[0159] This embodiment provides an integrated electromagnetic transmission system based on three-dimensional braided multifunctional Litz cable and its integrated manufacturing and end-processing method. It aims to achieve microscopic topological reconstruction of conductive, magnetically controlled, insulating and structural functions through the same three-dimensional braiding process, and is equipped with a complete back-end forming and connection process.

[0160] First, three-dimensional braided Litz yarn 1 was prepared. A four-step three-dimensional braiding machine was used to establish four independent yarn supply channels, loading multiple independently insulated conductive fiber bundles 3, independent magnetic fiber bundles 5, independent insulating fibers 7, and independent structural fibers 9 onto their respective spindles. Specifically, the conductive fiber bundles 3 were made of silver-plated copper fibers with a diameter of 50 μm, each bundle containing 37 conductive monofilaments 47 with a 3 μm thick polyimide insulating coating. The magnetic fiber bundles 5 were made of MnZn ferrite composite fibers with a relative permeability of 200. The insulating fibers 7 were made of polyimide fibers, and the structural fibers 9 were made of aramid fibers. In the braiding machine control system, the braiding angle is set to 45° and the transposition pitch is 5mm. Each yarn carrier moves along a predetermined path, causing the conductive fiber bundle 3 to extend along a spiral path in three-dimensional space and periodically transpose. Within each transposition pitch, radial and circumferential spatial positions are exchanged. Simultaneously, the magnetic fiber bundle 5 interweaves with the conductive fiber bundle 3, forming an array of mechanically interlocked nodes with a node density controlled at 30 nodes / cm³. The structural fiber 9 interweaves through the gaps in the conductive fiber bundle 3 at a 45° angle, forming an anchoring relationship. The insulating fiber 7 fills the interweaving gaps between the conductive fiber bundle 3 and the magnetic fiber bundle 5, forming the insulating region 6. The structural fiber 9 forms the skeleton, i.e., the structural region 8, that maintains the mesh topology. Thus, a three-dimensional braided Litz yarn 1 with a non-layered, integrated mesh topology is integrally formed in the same process. Its interior contains a conductive region 2 composed of conductive fiber bundles 3 and a magnetically controlled region 4 composed of magnetic fiber bundles 5, with no radially distributed interlayer interfaces between the functional regions.

[0161] Based on the aforementioned three-dimensional braided Litz wire 1, this embodiment further manufactures a hollow solenoid power inductor 20. During the braiding process, the distribution density of the magnetic fiber bundle 5 is continuously and gradually varied radially through a variable spindle braiding method, with a density of 65% near the axis and gradually decreasing to 40% towards the outside, forming a continuous topological gradient structure. In the magnetic control zone 4, the magnetic fiber bundle 5 and the conductive fiber bundle 3 form a magnetic confinement node at their spatial intersection. The magnetic fiber bundle 5 physically wraps the conductive fiber bundle 3 with a 50° spiral encirclement angle, constructing a continuous three-dimensional magnetic flux topology network that wraps the conductive zone 2. Simultaneously, water-soluble polyvinyl alcohol yarn is placed as a placeholder at a preset air gap target position. After molding, it is removed by water, forming an air gap 19 with a width of 0.5 mm between the central magnetic column 17 and the I-type yoke 18. The outer magnetic yoke 16 and the central magnetic column 17 together constitute an E-type magnetic yoke structure. When alternating current passes through the conductive zone 2, the magnetic flux 23 is confined in the three-dimensional continuous magnetic circuit formed by the magnetic control zone 4, achieving low-loss energy storage. Furthermore, by adjusting the weaving model, the same three-dimensional woven Litz wire 1 can also be directly molded into a planar spiral inductor 24, a multi-layer stacked inductor 25, a racetrack-shaped inductor 26, or a C-type inductor 27 to meet different spatial layout requirements.

[0162] In wireless charging applications, a three-dimensional braided Litz wire 1 is wound on a planar mold to form a planar spiral winding 13. Magnetic fiber bundles 5 are then integrally woven to form a magnetic circuit reinforcement layer 14 covering the upper and lower sides of the winding 13, thus constituting a wireless charging coil 12. Due to the deep coupling between the magnetocontrol region 4 and the conductive region 2 at the microscale, this wireless charging coil 12 possesses intrinsic electromagnetic shielding capabilities and can be directly integrated onto the surface of a flexible structure.

[0163] For the end connection of the three-dimensional braided Litz cable 1, this embodiment provides a complete end processing process. First, the cable end is fixed using a positioning clamp 31, and the cutting position is calibrated by an online detection and quality traceability unit 45. Then, the end insulation is removed using a plasma cutting device 32 or a laser cutting device 33, exposing the end of the conductive fiber bundle 3. Next, the end is moved to the working area of ​​the ultrasonic vibration unit 34, where a 20kHz high-frequency mechanical vibration is applied. The vibration energy acts on the micro-braiding nodes between the conductive fiber bundle 3, the insulating fiber 7, and the structural fiber 9, disrupting the mechanical interlocking topology and causing the conductive monofilaments 47 to detach from the braided mesh and disperse freely. The loosened conductive fiber bundle 3 is arranged in a bundling mold 35, and a hydraulic pre-compression device 36 is activated to apply a pressure of 10MPa for pre-compression, so that the volume fraction of conductive fibers reaches 60%. Subsequently, depending on the terminal specifications, an ultrasonic welding device 37, a laser welding device 38, or a friction stir welding device 39 can be selected to perform solid-state welding on the pre-pressed end preform, forming a metallurgical bond between the multiple conductive fiber bundles 3. After welding, the surface is polished by a polishing device 40, and then a nickel-tin alloy is plated by an electroplating device 41 to form an electroplated protective layer 30, ultimately producing a flat terminal body 29 with a width-to-thickness ratio of 10:1 and a contact resistance of less than 0.1mΩ. This flat terminal body 29 can be directly connected to the power module interface 46, or further stamped into an annular terminal 48 with mounting holes and a bent terminal 49 (see reference). Figure 15 ( ), to adapt to different assembly spaces.

[0164] For the three-dimensional braided Litz wire 1 with an internally integrated hollow cooling channel 43, after the welding step is completed, a sealing compound 44 is injected into the end of the hollow cooling channel 43, and a vacuum is drawn to -0.09 MPa. This allows the sealing compound 44 to penetrate into the fiber braid gaps under negative pressure and solidify, forming a sealed structure integrated with the welded end, ensuring the long-term sealing of the cooling medium. The entire end processing procedure is monitored in real time by an online detection and quality traceability unit 45, which monitors tension, resistance, and morphological parameters to ensure the consistency and reliability of the terminal connection structure.

[0165] Tests showed that the three-dimensional braided Litz wire 1 prepared in this embodiment has an AC resistance that is about 30% lower than that of the traditional Litz wire of the same cross-section under 100kHz and 1A current conditions. The hollow solenoid power inductor 20 has a quality factor Q of over 80 at 1MHz. The connection temperature rise between the flat terminal body 29 and the power module interface 46 is less than 5K, which meets the requirements of high frequency, high power density and high reliability integrated electromagnetic transmission.

[0166] Another embodiment: Toroidal three-dimensional braided power inductor

[0167] Reference Figure 7In this embodiment, the conductive region 2 of the toroidal three-dimensional braided power inductor is woven into a toroidal spiral winding by 14 independently insulated conductive fiber bundles 3. Each bundle consists of 7 silver-plated copper monofilaments with a diameter of 50μm, and the surface of the monofilaments is covered with a 5μm thick polyimide insulating layer. The magnetic control region 4 is woven into a toroidal magnetic core by iron-silicon-aluminum magnetic powder composite yarn along the direction of the toroidal magnetic lines of force, forming a closed magnetic circuit. The insulation region 6 is composed of polyimide tape wound and aramid filling, ensuring electrical isolation between adjacent winding turns and between the winding and the magnetic core. The structural region 8 is made of ultra-high molecular weight polyethylene fiber arranged on the outermost layer. During manufacturing, a two-step three-dimensional braiding machine is used to form it in one step on the toroidal core mold, with a braiding angle of 35° and a magnetic powder composite yarn filling rate of 45%. After heat setting, it is impregnated with epoxy resin and encapsulated. The resulting toroidal inductor has an outer diameter of 12mm, an inner diameter of 6mm, a thickness of 5mm, a measured inductance of 47μH (100kHz), a DC resistance of 55mΩ, a saturation current of 2.8A, and a quality factor Q greater than 60.

[0168] Another embodiment: Laser welding connection structure of flat rectangular terminals

[0169] Take a three-dimensional braided Litz wire 1 with a flat rectangular cross-section. It contains 12 bundles of silver-plated copper conductive fiber bundles 3. Each bundle consists of 16 conductive monofilaments 47 with a diameter of 50μm. The polyimide insulating layer on the surface of the monofilament is 8μm thick. The insulating fiber 7 is a polyimide fiber with a diameter of 200μm. The structural fiber 9 is a poly(p-phenylenebenzodioxazole) fiber with a diameter of 300μm. The cable end is fixed in the positioning fixture 31, and the 8mm long insulating fiber 7 at the end is removed by the laser cutting device 33 with a power of 200W, exposing the end of the conductive fiber bundle 3. Then, the end is loosened by the ultrasonic vibration unit 34 with a frequency of 20kHz and an amplitude of 25μm for 1s. The loosened 12 bundles of conductive fiber 3 are arranged in the rectangular cavity of the bundling mold 35, and the hydraulic pre-compression device 36 is used to pre-compress the fiber at a pressure of 10MPa, so that the volume fraction of conductive fiber reaches about 63%. Then, the laser welding device 38 is used under argon protection with a power of 800W, a spot diameter of 0.4mm, and a welding speed of 200mm / s to scan and weld along the width direction of the terminal to form a flat terminal body 29. After the terminal surface is polished, a nickel layer with a thickness of 3μm is electroplated by the electroplating device 41 as an electroplating protective layer 30. The resulting terminal connection structure 28 has a flat terminal body 29 with a width of 3.0 mm and a thickness of 0.2 mm, a width-to-thickness ratio of 15:1, a contact resistance of 0.04 mΩ, and a pull-out force of 210 N. It can be directly inserted into the power module interface 46 to achieve a high-density, low-loss electrical connection.

[0170] In summary, this invention achieves structural and functional integration of high-performance Litz cables through innovative three-dimensional braiding and solid-state welding processes, resulting in significant benefits. Firstly, in terms of mechanical performance, the mechanically interlocking nodes constructed using three-dimensional braiding technology tightly interlock the conductive, magnetically controlled, insulating, and structural fibers in space, forming a non-layered integral structure. This greatly enhances the cable's resistance to bending fatigue and structural stability, effectively solving the problem of interlayer separation that easily occurs in traditional cables under complex stress environments.

[0171] Secondly, regarding electrical connection performance, the unique end-treatment process of this invention, combining ultrasonic loosening, bundle pre-compression, and solid-state welding, successfully overcomes the challenge of fiber disintegration. This process achieves a high conductive fiber volume fraction of 50% to 70% at the terminal connection, and ensures a contact resistance of less than 0.1 mΩ through metallurgical bonding, significantly reducing energy loss during high-frequency transmission. Simultaneously, the flattened terminal design greatly improves heat dissipation efficiency and installation density.

[0172] Finally, this invention achieves deep integration of the magnetic circuit system and the cooling system. By precisely constructing the magnetically controlled air gap through a space-occupying braiding process and utilizing vacuum-assisted sealing technology to ensure the long-term sealing of the hollow cooling channel, the cable possesses both excellent electromagnetic shielding and powerful active heat dissipation capabilities. This highly integrated structure not only reduces space requirements but also significantly improves the system's power density and reliability, meeting the stringent requirements of high-end equipment for high-performance transmission cables.

[0173] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications should be covered within the scope of the claims of the present invention.

Claims

1. A three-dimensional braided multifunctional Litz cable, characterized in that, This includes a non-layered, integrated mesh topology formed by multiple independent yarn systems interlacing in the same three-dimensional weaving process: The conductive region (2) is composed of multiple independent insulating conductive fiber bundles (3). The conductive fiber bundles (3) extend along a spiral path and periodically change positions in the three-dimensional braid. In each change pitch, the radial and circumferential spatial positions are exchanged to form a statistically equal current path micro-topology. The magnetic control region (4) is composed of magnetic fiber bundles (5) independent of the conductive fiber bundles (3). The magnetic fiber bundles (5) intersect with the conductive fiber bundles (3) in three-dimensional space and form an array of mechanically interlocked nodes, thus constructing a continuous three-dimensional magnetic flux topology network that encloses the conductive region (2). The insulating region (6) is composed of independent insulating fibers (7) and fills the gap between the conductive fiber bundle (3) and the magnetic fiber bundle (5); The structural region (8) is composed of independent structural fibers (9) to form a skeleton that maintains the mesh topology; The mechanical interlocking nodes enable the magnetic fiber bundle (5) and the conductive fiber bundle (3) to be anchored to each other on a microscale, and there are no radially distributed interlayer interfaces between the functional areas.

2. The three-dimensional braided multifunctional Litz cable according to claim 1, characterized in that, The conductive fiber bundle (3) has a single conductive fiber diameter of 5 μm to 200 μm, and each bundle contains 3 to 128 conductive fibers. The surface is covered with a polyimide or ceramicized silicone rubber insulating coating with a thickness of 1 μm to 20 μm. The magnetic fiber bundle (5) is a ferrite composite fiber or an amorphous soft magnetic fiber with a relative permeability of 10 to 1000 and a volume fraction of 5% to 60%.

3. The three-dimensional braided multifunctional Litz cable according to claim 1, characterized in that, The node density of the mechanical interlocking nodes is 5 to 50 per cubic centimeter; at the mechanical interlocking nodes, the structural fiber (9) is... The interlacing angle passes through the gap of the conductive fiber bundle (3) and forms a point-to-line contact or surface-to-surface bonding anchoring relationship with the conductive fiber bundle (3).

4. A three-dimensional braided power inductor, characterized in that, Includes a three-dimensional braided structure having an integrated fiber microstructure: The conductive region (2) is formed by multiple bundles of independently insulated conductive fibers (3) arranged in transposition according to the Litz principle to form an inductor winding; The magnetocontrol zone (4) is composed of magnetic fiber bundles (5) to form a three-dimensional continuous magnetic circuit that surrounds or penetrates the conductive zone (2); The magnetic fiber bundle (5) forms a continuous topological gradient structure inside the three-dimensional braid, that is, the distribution density of the magnetic fiber bundle (5) gradually changes along the radial or axial direction, and the fibers continue to extend and intertwine in the gradual region without forming a physical interface with a sudden change in magnetic permeability.

5. The three-dimensional braided power inductor according to claim 4, characterized in that, The magnetic fiber bundle (5) and the conductive fiber bundle (3) form a magnetic confinement node at their spatial intersection; at the magnetic confinement node, the extension path of the magnetic fiber bundle (5) is perpendicular to the axis of the conductive fiber bundle (3). The spiral encirclement angle causes the magnetic fiber bundle (5) to form a physical encirclement path of the alternating magnetic flux generated by the conductive fiber bundle (3) at the node.

6. The three-dimensional braided power inductor according to claim 4, characterized in that, The magnetic control area (4) includes an E-type magnetic yoke, a central magnetic column (17) and an air gap (19); the air gap (19) is formed in the three-dimensional weaving process by a spaced weaving method, that is, during weaving, a removable water-soluble polyvinyl alcohol yarn or a removable core rod is set at the target position of the air gap, and after forming, the spacer is removed to form an air gap with a width of 0.1 mm to 2.0 mm.

7. A method for processing the end of a three-dimensional braided Litz yarn, used to process a three-dimensional braided Litz yarn (1) comprising insulating fibers (7) and structural fibers (9), characterized in that, Includes the following steps: Insulation removal steps: Remove end insulation using plasma cutting or laser cutting; Loosening step: High-frequency mechanical vibration of 15kHz to 40kHz is applied to the exposed conductive fiber bundle (3) end using an ultrasonic vibration unit (34). The energy of the vibration acts on the micro-weaving nodes between the conductive fiber bundle (3) and the insulating fiber (7) and structural fiber (9) to destroy the mechanical interlocking topology formed by the three-dimensional weaving process, so that the conductive fiber monofilaments are released from the weaving mesh and dispersed freely. Bundling and pre-compression steps: Arrange the separated conductive fiber bundles in the bundling mold (35) and pre-compress; Welding steps: Solid welding of the pre-pressed end preform is carried out by ultrasonic welding, laser welding or friction stir welding to form a metallurgical bond between the multiple conductive fiber bundles (3).

8. The three-dimensional braided Litz yarn end treatment method according to claim 7, characterized in that, The terminal connection structure (28) formed by the welding step includes a flat terminal body (29) and an electroplated protective layer (30) covering its surface; the width-to-thickness ratio of the flat terminal body (29) is 3:1 to 20:1, the volume fraction of conductive fibers is 50% to 70%, and the contact resistance is less than 0.1mΩ.

9. The three-dimensional braided Litz yarn end treatment method according to claim 7, characterized in that, When the three-dimensional braided Litz wire (1) has a hollow cooling channel (43), a sealing step is also included after the welding step: a sealing colloid (44) is injected into the end of the hollow cooling channel (43) and a vacuum is drawn to -0.1MPa to -0.08MPa, so that the sealing colloid (44) penetrates and solidifies to form a sealed structure integral with the welding end.

10. A method for manufacturing a three-dimensional braided multifunctional Litz cable according to claim 1 or 2, characterized in that, Includes the following steps: Multiple independently insulated conductive fiber bundles (3), independent magnetic fiber bundles (5), independent insulating fibers (7) and independent structural fibers (9) are loaded into the corresponding spindles of the three-dimensional braiding machine respectively; In the control system of the three-dimensional braiding machine, the routing path of each fiber bundle is set so that the conductive fiber bundle (3) is... The weaving angles and pitches from 1mm to 100mm are interwoven and arranged in three-dimensional space; The three-dimensional braiding machine is controlled to perform a three-dimensional braiding process. The mechanical interlocking node is formed by controlling the movement trajectory of the yarn carrier, and the conductive area (2), magnetic control area (4), insulation area (6) and structural area (8) are integrally formed.

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