Preparation method of liquid-free high-flexible intelligent composite cable for megawatt flash charging

Abstract

This invention relates to the field of high-power DC charging cables for new energy vehicles, and specifically to a method for preparing a liquid-free, highly flexible, intelligent composite cable for megawatt flash charging. The method includes the following steps: S1. Preparing raw materials for the cable core and insulation sheath; S2. Preparing highly flexible composite conductor units; S3. Preparing the main power core insulation structure; S4. Preparing highly flexible cabling; S5. Preparing the reinforcing protective layer and composite outer sheath; S6. Finished product testing and calibration, performing appearance, dimensional, electrical, and mechanical performance tests on the cable semi-finished product. This invention can produce a liquid-free, highly flexible, high current-carrying, lightweight, low-cost, industry-standard compliant, highly safe, and long-life megawatt-level flash charging cable.

Description

Technical Field

[0001] This invention relates to the field of high-power DC charging cables for new energy vehicles, and in particular to a method for preparing a liquid-free, highly flexible, intelligent composite cable for megawatt flash charging. Background Technology

[0002] With the rapid development of the new energy vehicle industry, users' demand for charging efficiency is increasing, and megawatt-level flash charging technology (charging power ≥1MW) has become a key direction for industry development. This technology can enable commercial vehicles to be quickly charged in 3-5 minutes and passenger vehicles to be charged to 80% in 5-10 minutes, thereby significantly shortening the charging waiting time and matching the charging experience of traditional fuel vehicles.

[0003] Currently, megawatt-level flash charging cables are mainly divided into two technical routes, each with its own unresolved core technical bottlenecks: Liquid-cooled flexible conductor route: This route uses coolant channels inside the cable to dissipate heat through forced convection of the circulating fluid. While it can support high current transmission and has a certain degree of flexibility, it has the following prominent drawbacks: First, the risk of leakage is high. The channel joints and seals are prone to aging and cracking under long-term bending conditions, and coolant leakage may cause short circuits or electric shock accidents. Second, the liquid-cooled flexible conductor route has a complex structure, requiring additional circulating pumps, liquid storage tanks, and pressure monitoring devices, resulting in a large overall weight. Third, the operation and maintenance costs are high, requiring regular coolant replacement and sealing performance checks, with its total life cycle cost reaching more than three times that of non-liquid-cooled cables.

[0004] Liquid-free cooling rigid conductor route: To carry DC currents exceeding 1000A, this route typically uses large-section, irregularly shaped, rigid copper wire tightly compressed conductors. However, this route faces two common industry challenges: First, flexibility and current-carrying capacity are difficult to balance. Due to their high compression coefficient, large single-wire diameter, and strong structural rigidity, rigid conductors experience internal shear stress concentration when the cable is bent. Frequent bending can easily lead to single-wire breakage or conductor distortion, failing to meet the high flexibility requirements of charging guns, such as high-frequency insertion and removal, coiling and storage, and ground dragging. Second, temperature rise can become uncontrolled under high-current conditions. The thermal conductivity of conventional cable insulation materials is only 0.2–0.3 W / (m·K), classifying them as thermal insulators. The Joule heat generated by the conductor is difficult to dissipate effectively, leading to heat accumulation and a rapid increase in temperature. Under continuous high-current operation, this can easily exceed safety limits, accelerating insulation aging and even causing melting or fire accidents.

[0005] Therefore, it is essential to design a method for preparing a liquid-free, highly flexible intelligent composite cable for megawatt flash charging to solve the aforementioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned problems and deficiencies, and to provide a method for preparing a liquid-free, highly flexible, intelligent composite cable for megawatt flash charging. This method can produce a megawatt-level flash charging cable that is liquid-free, highly flexible, has a large current carrying capacity, is lightweight, low-cost, meets industry standards, is highly safe, and has a long lifespan.

[0007] The technical solution of this invention is implemented as follows: A method for preparing a liquid-free, highly flexible intelligent composite cable for megawatt flash charging, characterized by including the following steps: S1. Prepare the raw materials that constitute the cable core and insulation wrapping layer, wherein the cable core includes the main power core, the grounding protection core, the auxiliary control core, and the high thermal conductivity flexible flame-retardant filler rope. The main power core includes a central flexible support unit, a high flexibility composite conductor unit, a thermally conductive insulation layer, an inner semi-conductive buffer layer, a composite shielding layer, an outer semi-conductive protective layer, and a distributed intelligent sensing unit for monitoring temperature and strain. The insulation wrapping layer includes a main wrapping layer, a reinforcing protective layer, and a composite outer sheath layer. The main wrapping layer is a high flexibility non-woven fabric, and the composite outer sheath layer includes a flame-retardant inner sheath and a wear-resistant outer sheath. S2. Preparation of highly flexible composite conductor unit: High-purity oxygen-free copper rods are selected and subjected to multi-pass continuous drawing and online high-temperature annealing softening treatment to produce ultra-fine soft oxygen-free round copper wires with a diameter of 0.10mm to 0.30mm, and the elongation of the copper wire is controlled to be ≥30%. After argon plasma activation pretreatment on the surface of the softened copper wire, a flexible graphene silver composite coating is prepared by low-temperature magnetron sputtering process. With the central flexible support unit as the axis, ultra-fine soft copper wires are stranded layer by layer from the inside to the outside, and the stranding direction of adjacent layers is controlled to be opposite, and the stranding pitch is gradually increased from the inside to the outside. After forming, a highly flexible composite conductor unit is obtained. S3. Preparation of the main power core insulation structure: Weigh the following raw materials according to the following mass ratio: matrix resin 40-70%, phase change microcapsules 15-30%, graphene thermally conductive filler 8-20%, crosslinking agent 0.5-2%, flame retardant 5-15%. Weigh the matrix resin, phase change microcapsules, graphene thermally conductive filler, crosslinking agent, and flame retardant, and obtain the insulating composite material through high-speed mixing, twin-screw melt blending, and granulation. Use an extruder to uniformly extrude the insulating composite material onto the outer wall of the high-flexibility composite conductor unit, controlling the extrusion temperature at 120℃-180℃. After extrusion, perform electron beam irradiation crosslinking to obtain a thermally conductive insulation layer. Sequentially extrude an inner semiconductive buffer layer, a composite shielding layer, and an outer semiconductive protective layer onto the outer wall of the thermally conductive insulation layer to complete the preparation of the main power core shielding structure. Use a semiconductive fixing strip to fix the distributed intelligent sensing unit axially parallel to the outer wall of the outer semiconductive protective layer. Simultaneously prepare the grounding protection core and the auxiliary control core. S4. High-flexibility cabling preparation: Using a high thermal conductivity flexible flame-retardant filler rope as the central filling unit, two main power cores, one grounding protection core, and two auxiliary control cores are buried in the high thermal conductivity flexible flame-retardant filler rope. The rope is stranded using a small-pitch reverse cabling process, and the gaps between the cores are simultaneously filled with the high thermal conductivity flexible flame-retardant filler rope. After cabling, the rope is wrapped with a total wrapping tape layer. S5. Preparation of reinforced protective layer and composite outer sheath layer: Aramid fiber reinforced protective layer is woven on the outer wall of the main wrapping tape layer; then, a double-layer co-extrusion process is used to extrude the flame-retardant inner sheath and the wear-resistant outer sheath in sequence. After extrusion, electron beam irradiation crosslinking is performed to obtain the cable semi-finished product. S6. Finished product inspection and calibration: The appearance, dimensions, electrical performance and mechanical performance of the cable semi-finished products are inspected, and the temperature and strain of the distributed intelligent sensing unit are calibrated. After passing the inspection, the finished product of the liquid-free high-flexibility intelligent composite cable for megawatt flash charging is obtained.

[0008] Preferably, the distributed intelligent sensing unit includes at least two sensing optical fibers arranged parallel to the main power core, several fiber Bragg grating temperature sensors, and several strain sensors. Several fiber Bragg grating temperature sensors are arranged side by side along the length of each sensing optical fiber, and several strain sensors are arranged side by side along the length of each sensing optical fiber. During the deployment process, the tension of the sensing optical fibers is controlled to be ≤5N, and there is no bending or tensile damage.

[0009] Preferably, the sensing optical fiber is wrapped with a polyimide protective sleeve of 0.2mm to 0.5mm thickness, and the fiber Bragg grating temperature sensors are arranged side by side on the sensing optical fiber at intervals of 0.5m to 2m, and the strain sensors are arranged side by side on the sensing optical fiber at intervals of 0.5m to 2m; the temperature measurement accuracy of the fiber Bragg grating temperature sensor is ±0.5℃, and the strain measurement range of the strain sensor is 0 to 5000με.

[0010] Preferably, the central flexible support unit is a highly elastic aramid composite soft core with a tensile strength ≥2200MPa, an elongation at break ≥3.5%, and a diameter of 1.5mm to 4.0mm; the highly flexible composite conductor unit is a type 6 ultra-soft layered stranded conductor, which is divided into at least 3 layers of ultra-fine soft oxygen-free copper wire stranded layers from the inside to the outside. Each stranded layer is made of multiple strands of annealed soft oxygen-free round copper wires with a diameter of 0.10mm to 0.30mm; the stranding directions of adjacent stranded layers are opposite, and the stranding pitch increases gradually from the inside to the outside, with a pitch ratio ranging from 10 to 22; the surface of the ultra-fine soft oxygen-free copper wire is coated with a flexible graphene-silver composite coating with a thickness of 0.5μm to 2μm.

[0011] Preferably, the thermally conductive insulating layer is a modified cross-linked polyolefin composite layer with a thickness of 1.2 mm to 2.5 mm; the modified cross-linked polyolefin composite layer is composed of a matrix resin, phase change microcapsules, graphene thermally conductive filler, cross-linking agent, and flame retardant; the phase change microcapsules are paraffin or melamine-formaldehyde core-shell structures with a phase change temperature of 60℃ to 85℃, a latent heat of phase change ≥180 J / g, and an addition mass ratio of 15% to 30%; the graphene thermally conductive filler is a composite of few-layer graphene and nano-aluminum nitride, with an addition mass ratio of 8% to 20%; the thermally conductive insulating layer has a breakdown strength ≥25 kV / mm, a thermal conductivity ≥3.5 W / (m·K), and a volume resistivity ≥1×10¹. 4 Ω・cm.

[0012] Preferably, both the inner semiconductive buffer layer and the outer semiconductive protective layer are semiconductive cross-linked polyolefin layers, and the thickness of both the inner and outer semiconductive buffer layers is 0.3 mm to 0.8 mm; the composite shielding layer includes a tin-plated copper strip wrapping layer, a tin-plated copper wire braiding layer, and an aluminum-plastic composite film longitudinal wrapping layer stacked sequentially from the inside out; the volume resistivity of both the inner and outer semiconductive buffer layers is 1×10³ to 1×10³. 5 Ω・cm; the tin-plated copper strip wrapping layer is an overlapping wrapping layer with an overlap rate ≥25% and a thickness of 0.05mm~0.1mm; the tin-plated copper wire braided layer has a braiding density ≥90% and a single wire diameter of 0.1mm~0.2mm; the aluminum-plastic composite film longitudinal wrapping layer has an overlap rate ≥30% and a thickness of 0.08mm~0.15mm.

[0013] Preferably, the flame-retardant inner sheath is a highly flexible, halogen-free, low-smoke flame-retardant cross-linked polyolefin composite material; the wear-resistant outer sheath is a hydrolysis-resistant polyether-modified polyurethane elastomer composite material; the flame-retardant inner sheath has a thickness of 0.8mm to 1.5mm, an oxygen index ≥38%, and an elongation at break ≥200%; the wear-resistant outer sheath has a thickness of 0.5mm to 1.2mm, a Shore hardness of 85A to 95A, a wear loss ≤8mm³, and a temperature range of -55℃ to 125℃.

[0014] Preferably, in step S1, the sputtering power of the low-temperature magnetron sputtering process is 800W to 1500W, the sputtering vacuum degree is ≤5×10⁻³Pa, the sputtering temperature is ≤80℃, and the coating thickness uniformity error is ≤±10%; when stranding in layers, the inner layer stranding pitch ratio is 10 to 13, the middle layer stranding pitch ratio is 14 to 18, the outer layer stranding pitch ratio is 19 to 22, and the outer diameter tolerance of the stranded conductor is ≤±0.1mm.

[0015] Preferably, in step S3, the cable pitch ratio is controlled between 8 and 12, the cable stranding direction is opposite to the stranding direction of the semi-conductive fixing tape, and the cable core non-roundness after cabling is ≤5%; in step S4, the inner layer extrusion temperature of the double-layer co-extrusion process is 130℃ to 160℃, the outer layer extrusion temperature is 160℃ to 190℃, the co-extrusion adhesion of the two layers is ≥99%, and the irradiation dose for irradiation crosslinking is 150kGy to 220kGy.

[0016] The beneficial effects of this invention are as follows: The liquid-free, highly flexible intelligent composite cable for megawatt flash charging not only has a highly thermally conductive, flexible, flame-retardant filling rope wrapped around the main power core, the grounding protection core, and the auxiliary control core within the insulation wrapping layer, but also includes a central flexible support unit, a highly flexible composite conductor unit, a thermally conductive insulation layer, an inner semiconductive buffer layer, a composite shielding layer, and an outer semiconductive protective layer arranged coaxially from the inside out. This structure enables a fully solid-state, liquid-free design, capable of stably carrying megawatt-level power transmission of 1500VDC / 1500A and above, with a peak charging power of 2.25MW. The steady-state temperature rise during continuous operation at 1500A is ≤35K, the minimum bending radius is as low as 2.5 times the cable's outer diameter, and the bending fatigue life exceeds 300,000 cycles. The unit weight is more than 35% lighter than liquid-cooled cables of the same specification. This design creates a megawatt-level flash charging cable that combines high current carrying capacity, low temperature rise, ultra-high flexibility, lightweight, low cost, strong anti-interference, compliance with industry standards, high safety, and long lifespan. It perfectly meets the full-scenario megawatt-level flash charging needs of new energy vehicle charging guns, which require high-frequency plugging and unplugging and flexible storage, and has significant industrialization value.

[0017] By synchronously filling the gaps between the cores with highly thermally conductive, flexible, flame-retardant filler ropes, a continuous radial and axial heat conduction channel can be constructed, quickly diffusing internal heat to the outer sheath and achieving natural convection heat dissipation.

[0018] The newly developed megawatt flash charging liquid-free, highly flexible intelligent composite cable forms a closed-loop, all-solid-state, liquid-free thermal management system, enabling stable transmission of megawatt-level high current. It abandons traditional liquid-cooling channels and circulation systems, employing an all-solid-state thermal management system of "source heat reduction → three-dimensional thermal conduction and diffusion across the entire chain → active temperature control due to phase change latent heat." This system achieves stable transmission of 1500VDC / 1500A megawatt-level power, with a steady-state temperature rise of ≤35K at 25℃, only 53.8% of the national standard allowable limit. It can also operate stably in extreme high-temperature environments up to 55℃. Furthermore, its unit weight is more than 35% lighter than liquid-cooled cables of the same specifications, fundamentally solving the industry pain points of liquid-cooled cables, such as leakage, complex structure, and high maintenance costs.

[0019] The end-to-end high-flexibility design overcomes the industry challenge of achieving both current carrying capacity and flexibility: Through the end-to-end flexible design of "ultra-fine annealed soft copper wire + gradient increasing pitch + loose stranding micro gap + aramid flexible core + reverse cabling", the minimum bending radius of the cable is as low as 2.5 times the outer diameter of the cable, far exceeding the industry standard of 4-8 times the outer diameter; the bending fatigue life exceeds 300,000 times, which is 2.5 times that of existing liquid-cooled products and more than 7 times that of hard conductor products without liquid cooling, perfectly adapting to the usage scenarios of high-frequency plugging and unplugging, coiling and storage, and outdoor dragging of charging guns.

[0020] To address the skin effect and multi-conductor proximity effect of pulsating DC high-frequency ripple in existing megawatt-level DC flash charging, a combined design of "ultra-fine monofilament + gradient layered reverse twisting + graphene silver composite coating" is used to optimize current distribution, increase effective current-carrying area, reduce high-frequency additional loss by more than 60%, and increase current carrying capacity of the same cross section by 20%, thus achieving DC flash charging.

[0021] Intelligent safety protection throughout the entire life cycle: The distributed intelligent sensing unit realizes real-time monitoring of temperature and strain of the entire cable line, accurately locates abnormal operating conditions, and can work with the charging pile control system to realize predictive overheat protection and mechanical damage early warning, solving the problem of lagging single-point temperature measurement protection and greatly improving the inherent safety of the charging system. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the liquid-free, highly flexible intelligent composite cable for megawatt flash charging in this invention.

[0023] Figure 2 This is a schematic diagram of the main power conductor in this invention.

[0024] Figure 3 This is a partial structural diagram of the present invention. Detailed Implementation Example

[0025] like Figure 1 and Figure 2 As shown, the preparation method of a liquid-free, highly flexible intelligent composite cable for megawatt flash charging according to the present invention includes the following steps: S1. Prepare the raw materials that constitute the cable core 1 and the insulation wrapping layer 2. The cable core 1 includes a main power core 11, a grounding protection core 12, an auxiliary control core 13, and a high thermal conductivity flexible flame-retardant filler rope 14. The main power core 11 includes a central flexible support unit 111, a high flexibility composite conductor unit 112, a thermally conductive insulation layer 113, an inner semi-conductive buffer layer 114, a composite shielding layer 115, an outer semi-conductive protective layer 116, and a distributed intelligent sensing unit 117 for monitoring temperature and strain. The insulation wrapping layer 2 includes a total wrapping layer 21, a reinforcing protective layer 22, and a composite outer sheath layer 23. The total wrapping layer 21 is a high flexibility non-woven fabric, and the composite outer sheath layer 23 includes a flame-retardant inner sheath 231 and a wear-resistant outer sheath 232. S2. Fabrication of the high-flexibility composite conductor unit 112: High-purity oxygen-free copper rods are selected and subjected to multi-pass continuous drawing and online high-temperature annealing softening treatment to produce ultra-fine soft oxygen-free round copper wires with a diameter of 0.10mm to 0.30mm. The elongation of the copper wire is controlled to be ≥30%, ensuring the flexibility of the conductor from the material source. After argon plasma activation pretreatment on the surface of the softened copper wire, a flexible graphene-silver composite coating is prepared by low-temperature magnetron sputtering process to improve the adhesion of the coating, avoid the impact of high-temperature annealing on the soft properties of the copper wire, and ensure the bending followability of the coating. With the central flexible support unit 111 as the axis, ultra-fine soft copper wires are stranded layer by layer from the inside to the outside, controlling the stranding direction of adjacent layers to be opposite, and the stranding pitch to gradually increase from the inside to the outside. After forming, the high-flexibility composite conductor unit 112 is obtained. S3. Preparation of the insulation structure of the main power core 11: The following raw materials are weighed according to the following mass ratio: matrix resin 40-70%, phase change microcapsules 15-30%, graphene thermally conductive filler 8-20%, crosslinking agent 0.5-2%, and flame retardant 5-15%. The materials are then mixed at high speed, melt-blended with a twin-screw extruder, and granulated to obtain an insulating composite material. The insulating composite material is uniformly extruded onto the outer wall of the high-flexibility composite conductor unit 112 using an extruder, with the extrusion temperature controlled at 120℃-180℃. After extrusion, electron beam irradiation crosslinking is performed to obtain a thermally conductive insulating layer 113. An inner semi-conductive buffer layer 114, a composite shielding layer 115, and an outer semi-conductive protective layer 116 are sequentially extruded onto the outer wall of the thermally conductive insulating layer 113 to complete the preparation of the shielding structure of the main power core 11. The distributed intelligent sensing unit 117 is fixed axially parallel to the outer wall of the outer semi-conductive protective layer using a semi-conductive fixing strip 118. The grounding protection core 12 and the auxiliary control core 13 are prepared simultaneously. S4. High-flexibility cabling preparation: Using a high thermal conductivity flexible flame-retardant filler rope 14 as the central filling unit, two main power cores 11, one grounding protection core 12, and two auxiliary control cores 13 are buried in the high thermal conductivity flexible flame-retardant filler rope 14. The cabling is formed by stranding using a small-pitch reverse cabling process. The gaps between the cores are simultaneously filled with the high thermal conductivity flexible flame-retardant filler rope 14 to ensure the roundness and thermal conductivity of the cabling cores. After cabling, the overall wrapping tape layer 21 is wrapped around the cabling. S5. Preparation of reinforced protective layer 22 and composite outer sheath layer 23: Aramid fiber reinforced protective layer 22 is woven on the outer wall of the total wrapping tape layer 21, and the weaving tension is controlled to be uniform and not affect the bending performance of the cable. Then, a double-layer co-extrusion process is used to extrude flame-retardant inner sheath 231 and wear-resistant outer sheath 232 in sequence. After extrusion, electron beam irradiation crosslinking is performed to obtain the cable semi-finished product. S6. Finished product inspection and calibration: The appearance, dimensions, electrical performance and mechanical performance of the cable semi-finished product are inspected, and the temperature and strain of the distributed intelligent sensing unit 117 are calibrated. After passing the inspection, the finished product of the liquid-free high-flexibility intelligent composite cable for megawatt flash charging is obtained.

[0026] The liquid-free, highly flexible intelligent composite cable for megawatt flash charging not only has a highly thermally conductive, flexible, flame-retardant filling rope 14 wrapped with the main power core 11, the grounding protection core 12, and the auxiliary control core 13 inside the insulation wrapping layer 2, but also includes a central flexible support unit 111, a highly flexible composite conductor unit 112, a thermally conductive insulation layer 113, an inner semiconductive buffer layer 114, a composite shielding layer 115, and an outer semiconductive protective layer 116 arranged coaxially from the inside to the outside. This structure enables a fully solid-state, liquid-free design, capable of stably carrying megawatt-level power transmission of 1500VDC / 1500A and above, with a peak charging power of 2.25MW. The steady-state temperature rise during continuous operation at 1500A is ≤35K, the minimum bending radius is as low as 2.5 times the cable's outer diameter, and the bending fatigue life exceeds 300,000 cycles. The unit weight is more than 35% lighter than liquid-cooled cables of the same specification. This design creates a megawatt-level flash charging cable that combines high current carrying capacity, low temperature rise, ultra-high flexibility, lightweight, low cost, strong anti-interference, compliance with industry standards, high safety, and long lifespan. It perfectly meets the full-scenario megawatt-level flash charging needs of new energy vehicle charging guns, which require high-frequency plugging and unplugging and flexible storage, and has significant industrialization value.

[0027] By synchronously filling the gaps between the cores with highly thermally conductive, flexible, flame-retardant filler ropes 14, a thermally conductive channel that runs through the entire radial and axial directions can be constructed, quickly diffusing internal heat to the outer sheath and achieving natural convection heat dissipation.

[0028] The newly developed megawatt flash charging liquid-free, highly flexible intelligent composite cable forms a closed-loop, all-solid-state, liquid-free thermal management system, enabling stable transmission of megawatt-level high current. It abandons traditional liquid-cooling channels and circulation systems, employing an all-solid-state thermal management system of "source heat reduction → three-dimensional thermal conduction and diffusion across the entire chain → active temperature control due to phase change latent heat." This system achieves stable transmission of 1500VDC / 1500A megawatt-level power, with a steady-state temperature rise of ≤35K at 25℃, only 53.8% of the national standard allowable limit. It can also operate stably in extreme high-temperature environments up to 55℃. Furthermore, its unit weight is more than 35% lighter than liquid-cooled cables of the same specifications, fundamentally solving the industry pain points of liquid-cooled cables, such as leakage, complex structure, and high maintenance costs.

[0029] The end-to-end high-flexibility design overcomes the industry challenge of achieving both current carrying capacity and flexibility: Through the end-to-end flexible design of "ultra-fine annealed soft copper wire + gradient increasing pitch + loose stranding micro gap + aramid flexible core + reverse cabling", the minimum bending radius of the cable is as low as 2.5 times the outer diameter of the cable, far exceeding the industry standard of 4-8 times the outer diameter; the bending fatigue life exceeds 300,000 times, which is 2.5 times that of existing liquid-cooled products and more than 7 times that of hard conductor products without liquid cooling, perfectly adapting to the usage scenarios of high-frequency plugging and unplugging, coiling and storage, and outdoor dragging of charging guns.

[0030] To address the skin effect and multi-conductor proximity effect of pulsating DC high-frequency ripple in existing megawatt-level DC flash charging, a combined design of "ultra-fine monofilament + gradient layered reverse twisting + graphene silver composite coating" is used to optimize current distribution, increase effective current-carrying area, reduce high-frequency additional loss by more than 60%, and increase current carrying capacity of the same cross section by 20%, thus achieving DC flash charging.

[0031] Intelligent safety protection throughout the entire life cycle: The distributed intelligent sensing unit 117 realizes real-time monitoring of temperature and strain of the entire cable line, accurately locates abnormal operating conditions, and can cooperate with the charging pile control system to realize predictive overheat protection and mechanical damage early warning, solving the problem of lagging single-point temperature measurement protection and greatly improving the inherent safety of the charging system.

[0032] The high-purity oxygen-free copper rod is a high-purity oxygen-free copper rod with a copper + silver content of not less than 99.996%. The semi-conductive fixing strip 118 can be made of semi-conductive nylon strip or similar material.

[0033] like Figure 2 and Figure 3 As shown, the distributed intelligent sensing unit 117 includes at least two sensing optical fibers 1171 arranged parallel to the main power core 11, several fiber Bragg grating temperature sensors 1172, and several strain sensors 1173. Several fiber Bragg grating temperature sensors 1172 and several strain sensors 1173 are arranged side-by-side along the length of each sensing optical fiber 1171. During installation, the tension of the sensing optical fibers 1171 is controlled to be ≤5N, preventing bending or tensile damage. This distributed intelligent sensing unit 117 can achieve real-time monitoring of temperature and strain along the entire cable line, accurately locating abnormal conditions such as local overheating and excessive bending. It works in conjunction with the charging pile control system to achieve predictive protection, solving the problem of lag in existing single-point temperature measurement protection. Simultaneously, fiber optic sensing possesses characteristics of anti-electromagnetic interference, passive operation, and long-distance transmission, perfectly adapting to megawatt flash charging scenarios in strong electromagnetic environments.

[0034] The fiber optic temperature sensor 1172 is of model SuperHawk2001T (Beijing Xizhuo) or FBGT series (Anhui Tiankang), and the strain sensor 1173 is of model MP-STS-1000-1-150 (Xiaoxiao Photonics [Microphotons]), Aut-S600 (Shanghai Wuliang [Auniontech]), or SS1000 (Beijing Xizhuo [Ray-testtech]).

[0035] like Figure 3 As shown, the sensing fiber 1171 is wrapped with a 0.2mm to 0.5mm thick polyimide protective sleeve. Each fiber Bragg grating temperature sensor 1172 is arranged side-by-side on the sensing fiber 1171 at intervals of 0.5m to 2m, and each strain sensor 1173 is also arranged side-by-side on the sensing fiber 1171 at intervals of 0.5m to 2m. The temperature measurement accuracy of the fiber Bragg grating temperature sensor 1172 is ±0.5℃, and the strain measurement range of the strain sensor 1173 is 0 to 5000με. This arrangement facilitates more accurate and stable temperature and strain monitoring, thereby improving the stability and safety of use, and ultimately enhancing reliability and applicability.

[0036] like Figure 1 and Figure 2 As shown, the central flexible support unit 111 is a highly elastic aramid composite soft core with a tensile strength ≥2200MPa, an elongation at break ≥3.5%, and a diameter of 1.5mm~4.0mm; the highly flexible composite conductor unit 112 is a type 6 ultra-soft layered stranded conductor, which is divided into at least 3 layers of ultra-fine soft oxygen-free copper wire stranded layers from the inside to the outside. Each stranded layer is made of multiple strands of annealed soft oxygen-free round copper wires with a diameter of 0.10mm~0.30mm. The stranding directions of adjacent stranded layers are opposite, and the stranding pitch increases gradually from the inside to the outside, with a pitch ratio range of 10~22; the surface of the ultra-fine soft oxygen-free copper wire is coated with a flexible graphene silver composite coating with a thickness of 0.5μm~2μm. Compared to traditional carbon fiber rigid cores, this central flexible support unit 111, with its aramid soft core, can deform synchronously with cable bending, eliminating rigid bending points and preventing compression damage during bending. It also possesses lightweight, high tensile strength, and resistance to bending fatigue, providing flexible central support for the conductor. This ensures ultra-high flexibility of the main power core 11 from the material source. The opposite stranding directions of adjacent stranded layers counteract stranding torque, preventing twisting, springback, and warping during cable bending. The stranding pitch increases gradually from the inside out, with a pitch ratio ranging from 10 to 22. The smaller pitch in the inner layer ensures conductor roundness and structural stability, while the larger pitch in the middle and outer layers provides greater flexibility to the copper wires, allowing them to slide freely and disperse stress during bending, achieving ultra-high flexibility and completely solving the problems of stress concentration and easy wire breakage during bending in rigid conductors.

[0037] The ultra-fine, soft, oxygen-free copper wire is coated with a flexible graphene-silver composite layer with a thickness of 0.5μm to 2μm. Its core functions are: ① To address the skin effect caused by high-frequency ripple in megawatt-level DC flash charging (10kHz to 100kHz), the single wire diameter is smaller than the skin depth in this frequency band (the skin depth of copper at 100kHz is approximately 0.21mm). Combined with the highly conductive surface coating, this reduces the conductor surface resistance and minimizes additional high-frequency losses; ② To address the proximity effect caused by high-current transmission from two parallel main power cores, the gradient-layered reverse twisting structure breaks the directional concentration of current, improving current distribution uniformity by over 40%, maximizing the effective current-carrying area, and reducing equivalent resistance and localized heating; ③ To reduce the contact resistance between copper wires, decrease heat generation, and simultaneously improve the copper wire's oxidation resistance, extending its service life.

[0038] The central flexible support unit 111 has a diameter of 2.5 mm and a tensile strength of 2500 MPa; the highly flexible composite conductor unit 112 has a 3-layer stranded structure, using 0.20 mm annealed oxygen-free soft copper wire, with an inner layer stranding pitch ratio of 12, a middle layer of 16, and an outer layer of 20, with adjacent layers stranded in opposite directions, and the copper wire surface is plated with a 1 μm thick flexible graphene silver composite coating; the thermally conductive insulating layer 113 has a thickness of 1.8 mm and a thermal conductivity of 3.8 W / (m·K); the inner semiconductive buffer layer 114 and the outer semiconductive protective layer 116 are both 0.5 mm thick; the distributed intelligent sensing unit 117 uses two fiber optic grating sensing fibers with polyimide sheaths, with a set of sensing points set every 1 m along the axial direction.

[0039] The thermally conductive insulating layer 113 is a modified cross-linked polyolefin composite layer, and the thickness of the thermally conductive insulating layer 113 is 1.2 mm to 2.5 mm. The modified cross-linked polyolefin composite layer is made from the following raw materials in the following mass ratios: matrix resin 40-70%, phase change microcapsules 15-30%, graphene thermally conductive filler 8-20%, cross-linking agent 0.5-2%, and flame retardant 5-15%; the phase change microcapsules are paraffin or melamine-formaldehyde core-shell structures, with a phase change temperature of 60℃-85℃ (lower than the maximum allowable operating temperature of 90℃ for cables), a phase change latent heat ≥180J / g, and an addition mass ratio of 15%-30%; the graphene thermally conductive filler is a composite of few-layer graphene and nano-aluminum nitride, and an addition mass ratio of 8%-20%; the thermally conductive insulation layer 113 has a breakdown strength ≥25kV / mm, a thermal conductivity ≥3.5W / (m·K), which is more than 12 times that of traditional insulation, and a volume resistivity ≥1×10¹. 4 Ω・cm. This enables the main power core 11 to have high stability and reliability, thereby improving the stability and safety of use, and further contributing to improved reliability and applicability.

[0040] The graphene thermally conductive filler forms a three-dimensional through-type thermally conductive network in the insulating matrix, which quickly conducts the heat generated by the conductor radially. When the temperature reaches the phase change point, the phase change microcapsule absorbs a large amount of latent heat through solid-liquid phase change, suppresses the temperature rise peak, and avoids the temperature rise under the impact of large current. It can achieve temperature rise control under large current without the need for an additional liquid cooling system.

[0041] like Figure 1 and Figure 2 As shown, both the inner semiconductive buffer layer 114 and the outer semiconductive protective layer 116 are semiconductive cross-linked polyolefin layers, and their thicknesses are both 0.3 mm to 0.8 mm. The composite shielding layer 115 includes a tin-plated copper strip wrapping layer 1151, a tin-plated copper wire braided layer 1152, and an aluminum-plastic composite film longitudinal wrapping layer 1153, which are stacked sequentially from the inside to the outside. The volume resistivity of both the inner semiconductive buffer layer 114 and the outer semiconductive protective layer 116 is 1×10³ to 1×10³. 5 The tin-plated copper strip wrapping layer 1151 is an overlapping wrapping layer with an overlap rate ≥25% and a thickness of 0.05mm~0.1mm; the tin-plated copper wire braided layer 1152 has a braiding density ≥90% and a single wire diameter of 0.1mm~0.2mm; the aluminum-plastic composite film longitudinal wrapping layer 1153 has an overlap rate ≥30% and a thickness of 0.08mm~0.15mm. This not only provides better buffering and protection but also better shielding, thereby helping to further improve reliability and applicability.

[0042] The inner semiconductive buffer layer 114 and the outer semiconductive protective layer 116 are tightly bonded to their adjacent layers without gaps, which can uniformly combine the electric field between the shielding layer 115 and the thermally conductive insulating layer 113, avoid local discharge caused by local electric field concentration, and improve the long-term operational stability of the cable.

[0043] A three-layer composite shielding structure can be formed on the composite shielding layer 115, forming a dual protection of "conductive + magnetic shielding". Copper strip wrapping and copper wire braiding realize low impedance grounding and effectively discharge induced current; aluminum-plastic composite film realizes high-frequency electromagnetic field shielding with a shielding effectiveness of ≥60dB, which can completely suppress electromagnetic interference generated by high current transmission and ensure the signal stability of the charging control system.

[0044] The composite shielding layer 115 is constructed using 0.08mm tinned copper strip wrapping (30% overlap), 0.15mm tinned copper wire braiding (92% density), and 0.1mm aluminum-plastic composite film longitudinal wrapping (35% overlap). This not only facilitates manufacturing and controls manufacturing costs but also ensures excellent shielding performance.

[0045] The cable core 1 has a cable pitch ratio of 8 to 12, and the cable twisting direction is opposite to the twisting direction of the semi-conductive fixing tape 118 to counteract the cable twisting torque and ensure the high flexibility of the cable after cabling.

[0046] The two main power wires 11 are DC+ and DC- respectively, and the two auxiliary control wires 13 are CC / CV wake-up and low-voltage auxiliary power supply respectively.

[0047] The total wrapping layer 21 has an overlap rate of ≥20% and a thickness of 0.1mm~0.2mm, ensuring the roundness of the cable core and not affecting the cable's bending performance. The reinforcing protective layer 22 is a high-modulus aramid fiber braided layer with a braiding density of ≥85%, a single filament fineness of 200D~400D, and a tensile strength of ≥20cN / dtex, which can significantly improve the cable's tensile and drag resistance, avoid damage to the conductor and sensing unit caused by external force stretching during use, and at the same time not affect the overall flexibility of the cable.

[0048] The main power conductor 11 has a nominal cross-section of 185 mm², the grounding protection conductor 12 has a nominal cross-section of 95 mm², and the auxiliary control conductor 13 has a nominal cross-section of 2.5 mm², with a cabling pitch ratio of 10. After cabling, a 0.15 mm thick high-flexibility non-woven fabric wrapping layer 21 is applied, with an overlap rate of 25%. The reinforcing protective layer 22 is a 300D aramid fiber braided layer with a braiding density of 88%.

[0049] like Figure 1 As shown, the flame-retardant inner sheath 231 is a highly flexible, halogen-free, low-smoke, flame-retardant cross-linked polyolefin composite material; the wear-resistant outer sheath 232 is a hydrolysis-resistant polyether-modified polyurethane elastomer composite material; the flame-retardant inner sheath 231 has a thickness of 0.8mm to 1.5mm, an oxygen index ≥38%, and an elongation at break ≥200%; the wear-resistant outer sheath 232 has a thickness of 0.5mm to 1.2mm, a Shore hardness of 85A to 95A, a wear loss ≤8mm³, and a temperature range of -55℃ to 125℃. This achieves excellent flame-retardant and wear-resistant effects, thereby helping to improve flame-retardant and wear-resistant performance, and further contributing to improved reliability and applicability.

[0050] The composite outer sheath layer 23 is formulated with an optimized formula for all operating conditions of the charging gun cable: the flame-retardant inner sheath 231 is a highly flexible halogen-free, low-smoke flame-retardant cross-linked polyolefin composite material. The matrix is ​​a compound system of ethylene-vinyl acetate copolymer (EVA) and linear low-density polyethylene (LLDPE). It contains environmentally friendly flame retardants such as aluminum hydroxide / magnesium hydroxide, POE toughening agents, hindered phenolic antioxidants, and light stabilizers. The thickness is 0.8mm to 1.5mm, the oxygen index is ≥38%, and the elongation at break is ≥200%. It has excellent flame retardancy, low smoke and halogen-free characteristics, and high flexibility, without affecting the bending performance of the cable, while providing secondary protection for the internal structure. The wear-resistant outer sheath 232 is a hydrolysis-resistant polyether-modified polyurethane elastomer (TPU) composite material. The matrix is ​​polyether-type TPU, compounded with nano-silica wear-resistant agent, benzotriazole UV inhibitor, carbodiimide hydrolysis inhibitor, and hindered phenol antioxidant. The thickness is 0.5mm to 1.2mm, the Shore hardness is 85A to 95A, the wear loss is ≤8mm³, and the temperature range is -55℃ to 125℃. It has excellent wear resistance, hydrolysis resistance, oil resistance, UV resistance and high resilience, perfectly adapting to the use needs of charging gun cables in all scenarios such as frequent dragging, bending, outdoor exposure to the sun, and contact with oil stains in underground garages.

[0051] The flame-retardant inner sheath 231 is 1.2mm thick, made of halogen-free, low-smoke flame-retardant polyolefin with an oxygen index of 40%; the wear-resistant outer sheath 232 is 0.8mm thick, made of polyether-modified TPU with a Shore hardness of 90A and an abrasion loss of 8mm³. This allows for excellent flame retardancy and abrasion resistance while controlling costs, thereby contributing to further improvements in reliability and applicability.

[0052] The newly developed megawatt flash charging liquid-free high-flexibility intelligent composite cable features an innovative design including a high-flexibility composite conductor unit, a full-link three-dimensional thermal management system for thermal conduction and phase change, a full-band composite shielding structure, a distributed fiber optic intelligent sensing unit, and a double composite weather-resistant outer sheath. It is equipped with a manufacturing process that includes gradient soft stranding, low-temperature co-extrusion composite, and non-destructive cabling.

[0053] In step S1, the sputtering power of the low-temperature magnetron sputtering process is 800W~1500W, the sputtering vacuum degree is ≤5×10⁻³Pa, the sputtering temperature is ≤80℃, and the coating thickness uniformity error is ≤±10%. During layered stranding, the inner layer stranding pitch ratio is 10~13, the middle layer stranding pitch ratio is 14~18, and the outer layer stranding pitch ratio is 19~22. The outer diameter tolerance of the stranded conductor is ≤±0.1mm. This allows for the fabrication of more reliable liquid-free, highly flexible intelligent composite cables for megawatt flash charging, thus facilitating the production of high-quality liquid-free, highly flexible intelligent composite cables for megawatt flash charging.

[0054] In step S3, the cabling pitch ratio is controlled between 8 and 12, the cabling stranding direction is opposite to the stranding direction of the semi-conductive fixing tape 118, and the cable core non-roundness after cabling is ≤5%. In step S4, the inner layer extrusion temperature of the double-layer co-extrusion process is 130℃~160℃, the outer layer extrusion temperature is 160℃~190℃, the co-extrusion adhesion of the two layers is ≥99%, there are no delamination or bubble defects, and the irradiation dose for irradiation crosslinking is 150kGy~220kGy. This allows for the preparation of more reliable liquid-cooled, highly flexible intelligent composite cables for megawatt flash charging, thus facilitating the preparation of high-quality liquid-cooled, highly flexible intelligent composite cables for megawatt flash charging. Example

[0055] A method for preparing a liquid-free, highly flexible intelligent composite cable for megawatt flash charging is basically the same as that in Example 1 in terms of structure and preparation method, with the core difference being the inclusion of the following steps: S1. Fabrication of Highly Flexible Composite Conductor Units: Using an aramid composite soft core as the central support, high-purity oxygen-free copper rods are drawn and annealed online to produce 0.20mm soft copper wires with an elongation ≥38%. After plasma pretreatment, a 1μm graphene-silver composite coating is prepared by low-temperature magnetron sputtering with a sputtering power of 1200W, a vacuum degree of 3×10⁻³Pa, and a sputtering temperature ≤70℃. The conductor units are then stranded in layers with a pitch ratio of 12 for the inner layer, 16 for the middle layer, and 20 for the outer layer, with adjacent layers stranded in opposite directions.

[0056] S2. Preparation of main power core: Prepare insulating composite material according to the formula, mix at 1000 rpm and 70℃ for 15 min at high speed, and then granulate by twin screw extrusion at 120-160℃; extrude the insulation layer at 140-170℃ using an extruder, and crosslink by 150kGy electron beam irradiation; extrude the inner semiconductive layer, copper tape wrapping, copper wire braiding, aluminum-plastic longitudinal wrapping, and extrude the outer semiconductive layer in sequence; fix the sensing fiber to the outer wall of the outer semiconductive layer with a semiconductive fixing tape, control the tension ≤3N, and complete the preparation of the main power core; prepare the PE core and auxiliary core simultaneously.

[0057] S3. Cable preparation: Centered on a high thermal conductivity filler rope, two main power cores, one PE core, and two auxiliary cores are evenly arranged and cabled in opposite directions with a pitch ratio of 10. The gaps are filled with high thermal conductivity filler rope, and a non-woven fabric wrapping tape is wrapped around the core to obtain the cable core.

[0058] S4. Sheath preparation: An aramid reinforcement layer is woven outside the cable core. A flame-retardant inner sheath and a wear-resistant outer sheath are extruded using a double-layer co-extrusion process. The inner layer temperature is 140-155℃, the outer layer temperature is 170-185℃, and cross-linking is carried out by 180kGy irradiation to obtain a semi-finished product.

[0059] S5. Inspection and Calibration: After completing the appearance, size, electrical and mechanical performance inspections, the sensing unit is calibrated for temperature strain. Once qualified, the finished product is obtained. Example

[0060] The liquid-free, highly flexible intelligent composite cable for megawatt flash charging provided in this embodiment has a rated voltage of 1500VDC, a rated current of 1200A, and a peak charging power of 1.8MW. Its structure and preparation method are basically the same as in Embodiment 2, with the core difference being: The main power core 11 has a nominal cross-section of 150mm², uses 0.15mm soft copper wire, and has an inner layer pitch ratio of 11, a middle layer of 15, and an outer layer of 19. The thermally conductive insulating layer 113 has a thickness of 1.5 mm and a thermal conductivity of 3.5 W / (m·K). The grounding protection conductor core 12 has a nominal cross-section of 70mm² and a cabling pitch ratio of 9. To compare the performance of Embodiment 2 and Embodiment 3, two comparative technical solutions are presented below.

[0061] Comparison with technical solution one The comparative technical solution is an existing conventional megawatt-level liquid-cooled charging cable with a rated voltage of 1500VDC and a rated current of 1500A. It adopts a 2×185mm² soft copper conductor + central liquid-cooled flow channel structure, XLPE insulation, single-layer copper wire braided shielding, and TPU outer sheath.

[0062] Comparison with technical solution two The comparative technical solution is an existing liquid-cooled hard conductor charging cable with a rated voltage of 1500VDC, a rated current of 1500A, and uses 2×185mm² irregular hard copper compacted conductors, XLPE insulation, single-layer shielding, and a standard cabling structure.

[0063] Performance testing Performance tests were conducted on the cables of Embodiment 2, Embodiment 3, Comparative Technical Scheme 1, and Comparative Technical Scheme 2. The test results are shown in the table below:

[0064] The test results show that: In Embodiment 2 of the present invention, under the all-solid-state liquid-cooled structure, the temperature rise during continuous operation at 1500A is only 32K, which is the same as that of liquid-cooled cables of the same specification. It can still operate stably in extreme high-temperature environments of 55℃, and fully realizes the liquid-cooled megawatt-level high current transmission. At the same time, the unit weight is 36.3% lighter than that of liquid-cooled cables, with significant advantages in lightweighting.

[0065] With a minimum bending radius of only 2.5 times the outer diameter and a bending life of over 300,000 cycles, its flexibility and fatigue resistance far exceed those of liquid-cooled cables and rigid conductor cables without liquid cooling. It completely solves the industry pain point that flexibility and current carrying capacity cannot be achieved simultaneously. At the same time, the outer sheath material system is adaptable to all working conditions and has full-line intelligent monitoring capabilities, which can be directly applied on a large scale.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a liquid-coolant-free high-flexibility intelligent composite cable for megawatt flash charging, characterized in that Includes the following steps: S1. Prepare the raw materials that constitute the cable core (1) and the insulation wrapping layer (2), wherein the cable core (1) includes the main power core (11), the grounding protection core (12), the auxiliary control core (13), and the high thermal conductivity flexible flame retardant filler rope (14). The main power core (11) includes a central flexible support unit (111), a high flexibility composite conductor unit (112), a thermally conductive insulation layer (113), an inner semi-conductive buffer layer (114), a composite shielding layer (115), an outer semi-conductive protective layer (116), and a distributed intelligent sensing unit (117) for monitoring temperature and strain. The insulation wrapping layer (2) includes a total wrapping layer (21), a reinforced protective layer (22), and a composite outer sheath layer (23). The total wrapping layer (21) is a high flexibility non-woven fabric, and the composite outer sheath layer (23) includes a flame retardant inner sheath (231) and a wear-resistant outer sheath (232). S2. Preparation of high-flexibility composite conductor unit (112): High-purity oxygen-free copper rod is selected for multi-pass continuous drawing and online high-temperature annealing softening treatment to make ultra-fine soft oxygen-free round copper wire with a diameter of 0.10mm to 0.30mm, and the copper wire elongation is controlled to be ≥30%. After the surface of the softened copper wire is pretreated by argon plasma activation, a flexible graphene silver composite coating is prepared by low-temperature magnetron sputtering process. With the central flexible support unit (111) as the axis, ultra-fine soft copper wires are stranded in layers from the inside to the outside, and the stranding direction of adjacent layers is controlled to be opposite. The stranding pitch increases gradually from the inside to the outside, and a highly flexible composite conductor unit (112) is obtained after forming. S3. Preparation of the insulation structure of the main power core (11): Weigh the following raw materials according to the following mass ratio: matrix resin 40-70%, phase change microcapsules 15-30%, graphene thermally conductive filler 8-20%, crosslinking agent 0.5-2%, flame retardant 5-15%, and obtain the insulation composite material by high-speed mixing, twin-screw melt blending, and granulation; use an extruder to uniformly extrude the insulation composite material onto the outer wall of the high-flexibility composite conductor unit (112), and control the extrusion temperature to be 120℃-180℃. After wrapping, electron beam irradiation crosslinking is performed to obtain a thermally conductive insulating layer (113); an inner semiconductive buffer layer (114), a composite shielding layer (115), and an outer semiconductive protective layer (116) are sequentially extruded onto the outer wall of the thermally conductive insulating layer (113) to complete the preparation of the shielding structure of the main power core (11); the distributed intelligent sensing unit (117) is fixed parallel to the outer wall of the outer semiconductive protective layer along the axial direction using a semiconductive fixing tape (118); the grounding protection core (12) and the auxiliary control core (13) are prepared simultaneously. S4. High-flexibility cabling preparation: Using a high thermal conductivity flexible flame-retardant filler rope (14) as the central filling unit, two main power cores (11), one grounding protection core (12), and two auxiliary control cores (13) are buried in the high thermal conductivity flexible flame-retardant filler rope (14). The rope is stranded using a small-pitch reverse cabling process, and the gaps between the cores are simultaneously filled with the high thermal conductivity flexible flame-retardant filler rope (14). After cabling, the rope is wrapped with a total wrapping tape layer (21). S5. Preparation of reinforced protective layer (22) and composite outer sheath layer (23): Aramid fiber reinforced protective layer (22) is woven on the outer wall of the main wrapping layer (21); then, a double-layer co-extrusion process is used to extrude flame-retardant inner sheath (231) and wear-resistant outer sheath (232) in sequence. After extrusion, electron beam irradiation crosslinking is performed to obtain cable semi-finished product; S6. Finished product inspection and calibration: The appearance, dimensions, electrical performance and mechanical performance of the cable semi-finished product are inspected, and the temperature and strain of the distributed intelligent sensing unit (117) are calibrated. After passing the inspection, the finished product of the liquid-free high-flexibility intelligent composite cable for megawatt flash charging is obtained.

2. The method for preparing the liquid-free cooling high-flexible intelligent composite cable for megawatt flash charging according to claim 1, characterized in that: The distributed intelligent sensing unit (117) includes at least two sensing optical fibers (1171) arranged in the direction parallel to the main power core (11), a number of fiber Bragg grating temperature sensors (1172), and a number of strain sensors (1173). A number of fiber Bragg grating temperature sensors (1172) are arranged side by side along the length direction on each sensing optical fiber (1171), and a number of strain sensors (1173) are arranged side by side along the length direction on each sensing optical fiber (1171). During the deployment process, the tension of the sensing optical fiber (1171) is controlled to be ≤5N, and there is no bending or tensile damage.

3. The method for preparing the liquid-free, highly flexible intelligent composite cable for megawatt flash charging according to claim 2, characterized in that: The sensing fiber (1171) is wrapped with a 0.2mm to 0.5mm thick polyimide protective sleeve. Each fiber Bragg grating temperature sensor (1172) is arranged side by side on the sensing fiber (1171) at a spacing of 0.5m to 2m. Each strain sensor (1173) is arranged side by side on the sensing fiber (1171) at a spacing of 0.5m to 2m. The temperature measurement accuracy of the fiber Bragg grating temperature sensor (1172) is ±0.5℃, and the strain measurement range of the strain sensor (1173) is 0 to 5000με.

4. The method for preparing the liquid-free, highly flexible intelligent composite cable for megawatt flash charging according to claim 1, characterized in that: The central flexible support unit (111) is a highly elastic aramid composite soft core with a tensile strength ≥2200MPa, an elongation at break ≥3.5%, and a diameter of 1.5mm to 4.0mm. The highly flexible composite conductor unit (112) is a type 6 ultra-soft layered stranded conductor. The highly flexible composite conductor unit (112) is divided into at least 3 layers of ultra-fine soft oxygen-free copper wire stranded layers from the inside to the outside. Each stranded layer is made of multiple strands of annealed soft oxygen-free round copper wires with a diameter of 0.10mm to 0.30mm. The stranding directions of adjacent stranded layers are opposite, and the stranding pitch increases gradually from the inside to the outside, with a pitch ratio range of 10 to 22. The surface of the ultra-fine soft oxygen-free copper wire is coated with a flexible graphene silver composite coating with a thickness of 0.5μm to 2μm.

5. The method for preparing the liquid-free, highly flexible intelligent composite cable for megawatt flash charging according to claim 1, characterized in that: The thermally conductive insulating layer (113) is a modified cross-linked polyolefin composite layer with a thickness of 1.2 mm to 2.5 mm. The modified cross-linked polyolefin composite layer is composed of a matrix resin, phase change microcapsules, graphene thermally conductive filler, cross-linking agent, and flame retardant. The phase change microcapsules are paraffin or melamine-formaldehyde core-shell structures with a phase change temperature of 60°C to 85°C, a latent heat of phase change ≥180 J / g, and an addition mass ratio of 15% to 30%. The graphene thermally conductive filler is a composite of few-layer graphene and nano-aluminum nitride, with an addition mass ratio of 8% to 20%. The thermally conductive insulating layer (113) has a breakdown strength ≥25 kV / mm, a thermal conductivity ≥3.5 W / (m·K), and a volume resistivity ≥1×10¹. 4 Ω・cm.

6. The method for preparing the liquid-free, highly flexible intelligent composite cable for megawatt flash charging according to claim 1, characterized in that: The inner semiconductive buffer layer (114) and the outer semiconductive protective layer (116) are both semiconductive cross-linked polyolefin layers, and the thickness of the inner semiconductive buffer layer (114) and the outer semiconductive protective layer (116) is 0.3 mm to 0.8 mm. The composite shielding layer (115) includes a tin-plated copper strip wrapping layer (1151), a tin-plated copper wire braiding layer (1152), and an aluminum-plastic composite film longitudinal wrapping layer (1153) stacked sequentially from the inside to the outside. The volume resistivity of the inner semiconductive buffer layer (114) and the outer semiconductive protective layer (116) is 1×10³ to 1×10³. 5 Ω・cm; the tin-plated copper strip wrapping layer (1151) is an overlapping wrapping layer with an overlap rate ≥25% and a thickness of 0.05mm~0.1mm; the tin-plated copper wire braided layer (1152) has a braiding density ≥90% and a single wire diameter of 0.1mm~0.2mm; the aluminum-plastic composite film longitudinal wrapping layer (1153) has an overlap rate ≥30% and a thickness of 0.08mm~0.15mm.

7. The method for preparing the liquid-free, highly flexible intelligent composite cable for megawatt flash charging according to claim 1, characterized in that: The flame-retardant inner sheath (231) is a highly flexible, halogen-free, low-smoke flame-retardant cross-linked polyolefin composite material; the wear-resistant outer sheath (232) is a hydrolysis-resistant polyether-modified polyurethane elastomer composite material; the flame-retardant inner sheath (231) has a thickness of 0.8mm to 1.5mm, an oxygen index ≥38%, and an elongation at break ≥200%; the wear-resistant outer sheath (232) has a thickness of 0.5mm to 1.2mm, a Shore hardness of 85A to 95A, a wear loss ≤8mm³, and a temperature range of -55℃ to 125℃.

8. The method for preparing the liquid-free, highly flexible intelligent composite cable for megawatt flash charging according to claim 1, characterized in that: In step S1, the sputtering power of the low-temperature magnetron sputtering process is 800W~1500W, the sputtering vacuum degree is ≤5×10⁻³Pa, the sputtering temperature is ≤80℃, and the coating thickness uniformity error is ≤±10%; when stranding in layers, the inner layer stranding pitch ratio is 10~13, the middle layer stranding pitch ratio is 14~18, the outer layer stranding pitch ratio is 19~22, and the outer diameter tolerance of the stranded conductor is ≤±0.1mm.

9. The method for preparing the liquid-free, highly flexible intelligent composite cable for megawatt flash charging according to claim 1, characterized in that: In step S3, the cable pitch ratio is controlled between 8 and 12, the cable stranding direction is opposite to the stranding direction of the semi-conductive fixing tape (118), and the cable core non-roundness after cabling is ≤5%; in step S4, the inner extrusion temperature of the double-layer co-extrusion process is 130℃~160℃, the outer extrusion temperature is 160℃~190℃, the co-extrusion adhesion of the two layers is ≥99%, and the irradiation dose of irradiation crosslinking is 150kGy~220kGy.

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