Cable for UPS (Uninterrupted Power Supply) energy storage system and manufacturing method thereof

Abstract

The invention discloses a cable for a UPS (Uninterrupted Power Supply) energy storage system and a manufacturing process thereof, the cable comprises a cable core part, the cable core part comprises a plurality of twisted conductive metal wires, graphene fiber bundles are embedded in twisting gaps of the conductive metal wires, and the twisted conductive metal wires are jointly coated with a conductive foil material. The insulating part wraps the outer side of the conductive foil, and the outer side wall of the insulating part is coated with a conductive carbon coating. And the shielding layer coats the outer side of the conductive carbon coating. And the explosion-proof part comprises an armor layer wrapping the outer side of the shielding part, a gap is reserved between the armor layer and the explosion-proof part, and the gap is filled with fireproof mud. The cable can greatly reduce the loss under large current transmission, and is good in heat dissipation and explosion-proof performance.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a cable for a UPS energy storage system and a manufacturing method thereof. Background Art

[0002] An uninterruptable power system (UPS) is a power protection device that includes an energy storage device and uses an inverter as its primary unit to provide voltage and frequency stabilization. Typically, a UPS system consists of a battery pack, a rectifier, an inverter, and a static switch, providing backup power. UPS systems require cables to supply power, and currents can reach hundreds to thousands of amperes. Traditional cables have high conductor resistance, resulting in significant energy loss and significant temperature rise. This results in significant power loss and reduces cable safety. Summary of the Invention

[0003] To overcome the above shortcomings, the purpose of the present invention is to provide a cable for a UPS energy storage system and a manufacturing method thereof, wherein the cable can reduce losses under high current transmission and has good heat dissipation and explosion-proof properties.

[0004] In order to achieve the above objectives, the technical solution adopted by the present invention is: a cable for a UPS energy storage system, comprising: A cable core, the cable core comprising a plurality of twisted conductive metal wires, wherein graphene fiber bundles are embedded in the twisted gaps between the conductive metal wires, and the twisted conductive metal wires are collectively coated with a conductive foil; An insulating portion, the insulating portion being wrapped around the outside of the conductive foil, and the outer wall of the insulating portion being coated with a conductive carbon coating; A shielding portion, wherein the shielding layer is coated on the outside of the conductive carbon coating; The explosion-proof part includes an armor layer covering the outside of the shielding part, a gap is left between the armor layer and the explosion-proof part, and the gap is filled with fireproof mud.

[0005] The beneficial effects of the present invention are: The cable core is constructed with graphene fiber bundles and coated with conductive foil, significantly improving conductivity, minimizing resistance, facilitating heat dissipation, and effectively suppressing the skin effect, meeting the demands of high-current transmission. When the stranded structure bends, the graphene fibers absorb localized stress concentration, evenly distributing strain on the conductive wires and extending their bending life.

[0006] Add explosion-proof part, which forms a double-layer structure of active expansion seal + passive metal protection. The dual mechanism significantly improves the explosion-proof level of the cable. Furthermore, the graphene fiber bundles are provided in a plurality and are arranged symmetrically with respect to the plurality of twisted conductive metal wires. The plurality of graphene fiber bundles improves electrical conductivity and heat dissipation, and the symmetrical structure allows for more uniform stress distribution across the graphene fiber bundles.

[0007] Furthermore, the conductive metal wire is an oxygen-free copper wire with a purity higher than 99%, the cross-sectional area of the twisted conductive metal wire ranges from 16 to 120 mm², and the conductive foil is a silver-plated copper foil with a thickness of 0.03 to 0.06 mm.

[0008] Specifically, the insulation comprises an inner layer and an outer layer. The inner layer is made of cross-linked polyethylene containing 15% nano-alumina filler, while the outer layer is made of polyvinylidene fluoride. The insulation layer is a double-layer structure designed to combine electrical performance and chemical protection requirements, making it suitable for high-temperature and highly corrosive environments.

[0009] Furthermore, the thickness of the inner layer is 1.2-2.0 mm, and the thickness of the outer layer is 0.4-0.6 mm. Specifically, the shielding layer comprises an inner shielding layer and an outer shielding layer, arranged sequentially from the inside out. The inner shielding layer is formed by wrapping tinned copper tape with an overlap ratio of greater than or equal to 40%. The outer shielding layer is braided with nickel-plated copper wire with a braid density of greater than or equal to 95%. This double-layer shielding structure combines high coverage with corrosion resistance, making it suitable for harsh environments.

[0010] Furthermore, the cable also includes a sheath layer coated on the outside of the armor layer. The sheath layer is made of a mixed material of halogen-free flame-retardant silicone rubber and polyethersulfone, and the outer surface of the sheath layer is pressed with anti-slip patterns.

[0011] The present invention further discloses a production process for a cable for a UPS energy storage system, which is used to produce the above-mentioned cable. The production process comprises: pre-treating the conductive metal wire and the graphene fiber bundle; The conductive metal wires are twisted by a stranding machine. During the twisting process of the conductive metal wires, the graphene fiber bundles are synchronously fed into the gaps through a yarn guide, and a conductive foil is wrapped around the twisted conductive metal wires to form a cable core. forming an insulation portion outside the cable core by an extruder; spraying a conductive carbon coating on the outside of the insulating portion; The electro-carbon coating is sequentially wrapped with a tinned copper tape and a braided nickel-plated copper wire to form a shielding portion; An armor layer is placed outside the shielding portion, and fireproof mud is filled between the shielding portion and the armor layer to form an explosion-proof portion; A sheath layer is formed outside the explosion-proof part by an extruder.

[0012] Furthermore, pre-treating the conductive metal wire includes heating the conductive metal wire to 70-90° C., and controlling the tension of the conductive foil during wrapping to be 5-8N.

[0013] Furthermore, forming the insulation portion outside the cable core by an extruder specifically includes: The wrapping speed of the tinned copper tape is 20 m / min, and the braiding angle of the nickel-plated copper wire is 45°±5°. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the structure of the cable in an embodiment of the present invention.

[0015] In the picture: 11. Conductive metal wire; 12. Graphene fiber bundle; 13. Conductive foil; 21. Inner layer; 22. Outer layer; 31. Inner shielding layer; 32. Outer shielding layer; 41. Armor layer; 42. Fireproof mud; 51. Sheath layer; DETAILED DESCRIPTION The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0016] In the description of the present invention, it should be noted that the terms "upper," "lower," "left," "right," "lateral," "longitudinal," "horizontal," "inner," and "outer" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships in which the inventive product is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0017] The present invention discloses a cable for a UPS energy storage system, comprising a cable core, an insulation portion, a shielding portion, an explosion-proof portion, and a sheath layer 51. The cable core is used for electrical conduction and signal transmission; the insulation portion provides insulation; the shielding portion shields against signal interference; the explosion-proof portion provides flame retardancy, enhancing cable safety; and the sheath layer effectively protects the cable. This multi-layered cable, designed for optimal cable use, offers high safety and mechanical strength.

[0018] As shown in the drawings, the cable core includes a plurality of twisted conductive metal wires 11 , and graphene fiber bundles 12 are embedded in the twisted gaps between the conductive metal wires 11 .

[0019] In this embodiment, graphene fiber bundles 12 are added to the cable core. These bundles form a continuous axial conductive path within the twisted interstices, forming a multi-level conductive system with the bulk conductivity of the conductive metal wires 11. The two-dimensional electron gas properties of graphene reduce the skin effect, reducing high-frequency impedance by 30%-50% (above 1 MHz). Furthermore, the elongation at break of the graphene fibers forms a gradient matching that of the conductive metal wires 11. When the twisted structure bends, the graphene fibers absorb the localized stress concentration, evenly distributing the strain in the conductive metal wires 11 and improving the bending life.

[0020] In one embodiment, the conductive metal wire 11 is oxygen-free copper wire with a purity exceeding 99%. When twisted, the twist pitch is greater than three times the diameter of the graphene bundle. In this embodiment, the conductive metal wire 11 has a single filament diameter of 0.2 mm and a twist pitch of 15-20 mm. The diameter of the graphene fiber bundle 12 is 0.3 mm.

[0021] The cable core has the following Figure 1 The performance comparison results of the cable with 9 graphene fiber bundles 12 and without graphene fiber bundles 12 are shown in the following table.

[0022] Table 1 Performance comparison of graphene fiber bundles with and without graphene fiber bundles

[0023] It can be seen from Table 1 that the introduction of the graphene fiber bundle 12 can significantly improve the high-frequency conductivity, mechanical strength and thermal stability of the conductor.

[0024] In one embodiment, the twisted conductive metal wires 11 are coated with a conductive foil 13. The conductive foil 13 in this embodiment is a silver-plated copper foil, which is spirally wound at an inclination angle of 30-45° and an overlap rate of 15-30%. The silver layer faces the conductive metal wires 11 to reduce contact resistance.

[0025] Compared with the existing twisted structure of only conductive metal wires 11, the cable core in this embodiment has a graphene fiber bundle 12 embedded therein and is coated with a conductive foil 13 on the outside, which greatly improves the conductivity, reduces the resistance, facilitates heat dissipation, effectively suppresses the skin effect, and can meet the transmission needs of such large currents.

[0026] The cross-sectional area of the stranded conductive wire 11 ranges from 16 to 120 mm², and the conductive foil 13 is silver-plated copper foil with a thickness of 0.03 to 0.06 mm. The stranded conductive wire 11 has cross-sectional areas of 16 mm², 25 mm², 50 mm², 70 mm², 95 mm², and 120 mm², with a compression coefficient of ≥0.90.

[0027] In one embodiment, the wrapping direction of the conductive foil 13 is opposite to the twisting direction of the conductive wires 11 , so as to enhance structural stability.

[0028] In one embodiment, a single graphene fiber bundle 12 is provided, positioned centrally between the plurality of conductive metal wires 11. To improve conductivity and heat dissipation, multiple graphene fiber bundles 12 are provided, symmetrically arranged relative to the center of the twisted plurality of conductive metal wires 11. For example, as shown in the accompanying drawings, there are nine graphene fiber bundles 12, forming a centrally stacked structure.

[0029] The insulating portion is wrapped around the conductive foil 13, and the outer wall of the insulating portion is coated with a conductive carbon coating. A 0.02mm thick conductive carbon coating on the insulating portion provides electromagnetic shielding, prevents static electricity, and improves cable safety. The conductive carbon coating can be applied using a carbon nanotube dispersion, graphene coating, or a carbon black / polymer composite material through spraying, dip coating, roller coating, or other methods.

[0030] In one embodiment, the insulating layer is a double-layer structure. The design of the insulating layer combines electrical performance and chemical protection requirements and is suitable for high-temperature and highly corrosive environments.

[0031] The insulating portion includes an inner layer 21 and an outer layer 22 from the inside out. The inner layer 21 is made of cross-linked polyethylene containing nano-alumina filler, and the content of the nano-alumina is 15%. The inner layer 21 provides high electrical insulation and temperature resistance. Adding nano-alumina filler can improve corona resistance, suppress local discharge, and enhance thermal conductivity and mechanical strength. The outer layer 22 is made of polyvinylidene fluoride to resist electrolyte corrosion. In the insulating portion, the inner layer 21 plays a major protective role. Therefore, the thickness of the inner layer 21 is greater than that of the outer layer 22. For example, the thickness of the inner layer 21 is 1.2-2.0 mm, and the thickness of the outer layer 22 is 0.4-0.6 mm.

[0032] The shielding layer, wrapped around the conductive carbon coating, suppresses electromagnetic interference (EMI), evens out the electric field, and provides mechanical protection. In this embodiment, the shielding layer also employs a double-layer structure, comprising an inner shielding layer 31 and an outer shielding layer 32, arranged from the inside out. The inner shielding layer 31 is formed by wrapping tinned copper tape, while the outer shielding layer 32 is braided from nickel-plated copper wire. This double-layer shielding structure combines high coverage with corrosion resistance, making it suitable for harsh environments.

[0033] In one embodiment, the overlap ratio of the tinned copper tape wrapping is greater than or equal to 40% to ensure seamless coverage. Overlap ratio = (bandwidth - actual coverage width) / bandwidth × 100%. For example, if the tinned copper tape has a 20mm bandwidth and an actual coverage width of 12mm, the overlap ratio = (20 - 12) / 20 = 40%. The braid density of the nickel-plated copper wire is greater than or equal to 95% to ensure near-complete coverage.

[0034] The explosion-proof part also has a double-layer structure, which includes an armor layer 41 wrapped around the outside of the shielding part. A gap is left between the armor layer 41 and the explosion-proof part, and the gap is filled with fireproof mud 42. The double-layer explosion-proof part has both active fire protection and passive protection capabilities.

[0035] Fireproof mortar 42 is an intumescent fireproof mortar. The intumescent agent (such as graphite or silicate) in fireproof mortar 42 rapidly vaporizes, forming a foamy carbonized layer (expanding 3-5 times). This layer seals the gaps between the cables, isolates oxygen, and prevents the longitudinal spread of flames. After expansion, the volume must completely fill the gaps within the armor layer 41. Armor layer 41 is a corrugated stainless steel armor layer 41, which is more flexible and has greater compressive strength than flat tape armor. The explosion-proof section forms a dual-layer structure of active expansion seal and passive metal shielding. This dual mechanism significantly enhances the cable's explosion-proof rating.

[0036] The addition of the explosion-proof portion greatly improves the explosion-proof and fire-proof performance of the cable in this embodiment compared to the prior art without the explosion-proof portion. The performance comparison of the cable with and without the explosion-proof portion is shown in Table 2 below.

[0037] Table 2 Performance comparison of cables with and without explosion-proof parts

[0038] As can be seen from Table 2, the explosion-proof and fire-proof performance of cables with explosion-proof parts are significantly better than those without explosion-proof parts.

[0039] In one embodiment, the thickness of the fireproof mud 42 is 0.5 mm-1.0 mm, and the thickness of the armor layer 41 is 0.2-0.4 mm. The armor layer 41 should not be too thick, otherwise it will affect the folding of the cable.

[0040] The sheath layer 51, covering the outer surface of the armor layer 41, is made of a blend of halogen-free flame-retardant silicone rubber and polyethersulfone (PES). This blend of halogen-free flame-retardant silicone rubber and polyethersulfone (PES) is a high-performance composite sheath solution that combines flexibility, temperature resistance, flame retardancy, and environmental tolerance, making it suitable for harsh environments.

[0041] In one embodiment, the outer surface of the sheath layer 51 is pressed with anti-slip grooves. The anti-slip grooves are formed on the sheath layer 51 to avoid being pressed. The depth of the anti-slip grooves is 0.4mm-0.6mm, and the friction coefficient of the anti-slip grooves is ≥0.8, which prevents the cable from sliding in the battery compartment and causing the interface to loosen.

[0042] In one embodiment, 7 strands of 0.2mm diameter oxygen-free copper wire are twisted together, the outer layer 22 is wrapped with 0.05mm silver-plated copper foil, and three graphene fiber bundles 12 are embedded in the center to form the cable core. The inner insulation layer 21 is 1.5mm thick, the outer insulation layer 22 is 0.5mm thick, and the conductive carbon coating is 0.02mm thick. The tinned copper tape has a 45% overlap ratio, the nickel-plated copper wire has a 96% braid density, the fireproofing mortar 42 is 1.2mm thick, and the armor layer 41 is 0.3mm thick. The sheath is a silicone rubber / PES blend (ratio 8:2), 2.0mm thick, and has a surface anti-slip groove depth of 0.6mm. This results in a cable with a cross-sectional area of 35mm². This cable was tested, and the test results are shown in the following table.

[0043] Table 3 Cable performance test results

[0044] As can be seen from Table 2, the cable in this embodiment adopts a multi-layer structure, which greatly improves electrical conductivity, temperature conductivity, explosion-proof function, and service life. It can meet the use requirements of UPS energy storage systems and solves the problems of high loss, corrosion susceptibility, and insufficient explosion-proof performance of cables under high current transmission. Its electrical conductivity efficiency is increased by 12%, and its explosion-proof and flame-retardant rating reaches UL94 V-0.

[0045] In one embodiment, a cable production process for a UPS energy storage system is used to produce the above-mentioned cable, and the production process includes a cable core processing step, an insulation processing step, a shielding processing step, an explosion-proof part processing step, and a sheath layer processing step.

[0046] The cable core processing steps include: First, the conductive metal wire 11 and the graphene fiber bundle 12 are pre-processed.

[0047] Pre-treating the conductive metal wires 11 includes heating the conductive metal wires 11 to 70-90°C. The heated conductive metal wires 11 are less likely to deform or break during twisting. Pre-treating the graphene fiber bundles 12 includes immersing the graphene fiber bundles 12 in a 0.5 wt% silane coupling agent (KH-550) ethanol solution and drying them at 60°C for 2 hours to prevent fiber agglomeration during twisting.

[0048] Next, the conductive metal wires 11 are twisted using a twisting machine. During the twisting process of the conductive metal wires 11, the graphene fiber bundles 12 are synchronously fed into the gap through a yarn guide, and at the same time, a conductive foil 13 is wrapped around the twisted conductive metal wires 11 to form a cable core.

[0049] During this process, the tension of the conductive metal wire 11 is maintained at 20-30N, and the tension of the graphene fiber bundle 12 is maintained at 5-8cN to prevent overload and breakage of the fiber bundle or deformation of the metal conductive wire. The yarn guide is kept 3-5mm away from the twisting point to ensure accurate fiber entry into the twisting gap. During the twisting process, the twist pitch is controlled at 15-20mm. The tension of the conductive foil 13 during wrapping is controlled at 5-8N.

[0050] In one embodiment, in order to prevent the graphene fiber bundle 12 from breaking, a yarn guide may not be provided during the process of stranding the conductive metal wire 11 by the stranding machine, and a ceramic guide eye reserved channel may be used instead, and the graphene fiber bundle 12 may be introduced into the reserved channel.

[0051] The insulation processing steps include: forming an insulation portion outside the cable core by an extruder; A conductive carbon coating is sprayed on the outside of the insulating portion.

[0052] The insulation has a double-layer structure. During the insulation processing, cross-linked polyethylene containing nano-alumina filler is extruded through a 150°C high-temperature extruder to coat the cable core, forming the inner layer 21. Polyvinylidene fluoride is then extruded again at 180°C to form the outer layer 22. The extruder uses a dual-channel co-extrusion die, with the inner and outer channels at a 45° angle to prevent material mixing. An annular spray nozzle is installed 5 cm from the die's exit, allowing the conductive carbon coating to be applied simultaneously with extrusion.

[0053] The shield processing steps include: The shield is formed by sequentially wrapping a tinned copper tape and braiding nickel-plated copper wire around the electro-carbon coating. The tinned copper tape is wrapped at a speed of 20 m / min, and the braiding angle of the nickel-plated copper wire is 45°±5°. The overlap ratio of the tinned copper tape is ≥40%, and the braiding density of the nickel-plated copper wire is ≥95%.

[0054] The shield processing steps include: Fireproof mud 42 is applied to the outside of the shielding part, and after solidification, an armoring forming machine is used to form an armor layer 41 outside the fireproof mud 42. The armor layer 41 is continuously formed by a stainless steel strip through a rolling die, and then the corrugated seams are laser welded.

[0055] The sheathing process includes forming the sheathing layer over the explosion-proof portion using an extruder. The silicone rubber / PES blend is co-extruded through a twin-screw extruder at 200°C, water-cooled, and then shaped using a traction machine. Finally, anti-slip grooves are directly pressed onto the sheathing layer using a mold at a traction machine speed of 10 m / min.

[0056] In this embodiment, although the cable has many layers, the cable can be quickly processed using existing processing technology.

[0057] The above embodiments are only for illustrating the technical concept and features of the present invention. Its purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. It cannot be used to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A cable for a UPS energy storage system, characterized by: include: A cable core, the cable core comprising a plurality of twisted conductive metal wires, wherein graphene fiber bundles are embedded in the twisted gaps between the conductive metal wires, and the twisted conductive metal wires are collectively coated with a conductive foil; An insulating portion, the insulating portion being wrapped around the outside of the conductive foil, and the outer wall of the insulating portion being coated with a conductive carbon coating; A shielding portion, wherein the shielding layer is coated on the outside of the conductive carbon coating; The explosion-proof part includes an armor layer covering the outside of the shielding part, a gap is left between the armor layer and the explosion-proof part, and the gap is filled with fireproof mud.

2. The UPS energy storage system cable according to claim 1, characterized in that: A plurality of graphene fiber bundles are provided, and the plurality of graphene fiber bundles are symmetrical with respect to the center of the plurality of twisted conductive metal wires.

3. The cable for a UPS energy storage system according to claim 1, wherein: The conductive metal wire is an oxygen-free copper wire with a purity higher than 99%. The cross-sectional area of the twisted conductive metal wire ranges from 16 to 120 mm². The conductive foil is a silver-plated copper foil with a thickness of 0.03 to 0.06 mm.

4. The cable for a UPS energy storage system according to claim 1, wherein: The insulating part includes an inner layer and an outer layer from the inside to the outside. The inner layer is made of cross-linked polyethylene containing nano-alumina filler, and the content of the nano-alumina is 15%. The outer layer is made of polyvinylidene fluoride.

5. The cable for a UPS energy storage system according to claim 4, characterized in that: The thickness of the inner layer is 1.2-2.0 mm, and the thickness of the outer layer is 0.4-0.6 mm.

6. The cable for a UPS energy storage system according to claim 1, characterized in that: The shielding part includes an inner shielding layer and an outer shielding layer arranged in sequence from the inside to the outside. The inner shielding layer is formed by wrapping tinned copper tape, and the overlap rate of the tinned copper tape wrapping is greater than or equal to 40%. The outer shielding layer is formed by weaving nickel-plated copper wire, and the weaving density of the nickel-plated copper wire is greater than or equal to 95%.

7. The UPS energy storage system cable according to any one of claims 1 to 6, characterized in that: The cable further comprises a sheath layer coated on the outside of the armor layer. The sheath layer is made of a mixed material of halogen-free flame-retardant silicone rubber and polyethersulfone. The outer surface of the sheath layer is pressed with anti-slip patterns.

8. A production process for cables for UPS energy storage systems, characterized by: Used to produce the cable according to any one of claims 1 to 7, the production process comprises: pre-treating the conductive metal wire and the graphene fiber bundle; The conductive metal wires are twisted by a stranding machine. During the twisting process of the conductive metal wires, the graphene fiber bundles are synchronously fed into the gaps through a yarn guide, and a conductive foil is wrapped around the twisted conductive metal wires to form a cable core. forming an insulation portion outside the cable core by an extruder; spraying a conductive carbon coating on the outside of the insulating portion; The electro-carbon coating is sequentially wrapped with a tinned copper tape and a braided nickel-plated copper wire to form a shielding portion; An armor layer is placed outside the shielding portion, and fireproof mud is filled between the shielding portion and the armor layer to form an explosion-proof portion; A sheath layer is formed outside the explosion-proof part by an extruder.

9. The production process for cables for UPS energy storage systems according to claim 8, characterized in that: The pretreatment of the conductive metal wire includes heating the conductive metal wire to 70-90° C., and controlling the tension of the conductive foil during wrapping to be 5-8N.

10. The process for producing cables for energy storage systems according to claim 8, characterized in that: When the electro-carbon coating is sequentially wrapped around the tinned copper tape and braided nickel-plated copper wire to form a shielding portion, the wrapping speed of the tinned copper tape is 20 m / min, and the braiding angle of the braided nickel-plated copper wire is 45±5°.

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