Direct current cable of energy storage system

Abstract

The utility model discloses an energy storage system DC cable comprising a conductor, and the outer side of the conductor is sequentially wrapped by a composite isolation layer, an insulation layer, an anti-spraying layer, a ceramic protection layer, a metal fiber shielding layer and a sheath layer. The conductor is of a layered winding structure, and the winding pitch is 6-8 times of the twisting outer diameter of the conductor. The direct-current cable of the energy storage system has excellent bending performance and tensile performance, also has excellent electrical insulation performance, and can ensure stable insulation performance in both high-temperature and low-temperature environments; meanwhile, the cable is fireproof, waterproof, damp-heat-resistant and excellent in flame retardant property; moreover, the cable can resist electromagnetic interference, thereby guaranteeing the stability of signal transmission. In addition, the cable is small in outer diameter and light in weight, and can meet the requirements of light weight and flexibility of the cable.

Description

Technical Field

[0001] This utility model belongs to the field of wire and cable technology, and specifically relates to a DC cable for an energy storage system. Background Technology

[0002] The statements herein provide only background information related to this invention and do not necessarily constitute prior art.

[0003] Against the backdrop of accelerated energy structure transformation, the roadmap for high-quality, large-scale development of new energy storage is becoming increasingly clear. Among the development paths for new energy storage, electrochemical energy storage has the widest range of applications, including: grid side, generation side, power supply side, microgrids, data centers, and communication base stations. With the further expansion of the energy storage market, lithium battery companies with first-mover advantages are expected to continue to increase their market share.

[0004] Future energy storage technologies will exhibit a trend towards greater integration and modularity. Integrated energy storage systems can combine multiple energy storage technologies to enable different energy storage forms to work synergistically and improve energy conversion efficiency. Modular energy storage systems can be flexibly expanded and combined according to needs to meet various scale and performance requirements.

[0005] Therefore, the future development trend of energy storage technology will exhibit characteristics of higher energy density, greater intelligence and controllability, and greater integration and modularity. In the future, the development of energy storage technology will further promote the popularization and utilization of renewable energy, creating a cleaner, more efficient, and sustainable energy future for humanity.

[0006] Faced with the finite nature of traditional energy sources and the severe damage and pollution they cause to the atmosphere and environment due to their widespread use, the research and application of clean new energy sources has become an important strategy for technological development in countries around the world. Among these, energy storage systems, with strong support and promotion from various countries, have entered a period of rapid development. And for industrial applications, cables—a crucial component of energy storage systems—will also usher in a golden age of new product development, accompanying the overall development of these systems.

[0007] Energy storage cables are commonly used in energy storage systems, generally referring to the connecting cables between batteries, between battery banks, and between battery banks and combiner boxes or converters in battery energy storage systems. These cables are used in DC systems with rated voltages of DC 600V, DC 1000V, and DC 1500V, and have a maximum temperature resistance of 125℃. Due to the special operating environment of energy storage cables, strict requirements are placed on their thermal life, resistance to high and low temperatures, acid and alkali resistance, battery acid resistance, salt spray resistance, UV resistance, low smoke and halogen-free properties, and combustion performance.

[0008] Connecting cables for power energy storage systems are mainly used for connections between battery modules, battery clusters, battery clusters and combiner boxes, and battery clusters and energy storage converters on the DC side of the power energy storage system. They are an indispensable part of the energy storage system and have huge market potential.

[0009] With the rapid development of energy storage technology, the performance requirements for connecting cables in electrochemical energy storage systems are increasing. The inventors discovered the following problems with traditional DC cables:

[0010] Insufficient mechanical properties: The conductor is prone to stress concentration due to frequent bending, resulting in poor tensile strength and an outer diameter that is easy to exceed the standard;

[0011] Poor insulation stability: The insulation layer has insufficient adhesion under high temperature (125℃) and low temperature (-40℃) conditions, making it prone to cracking;

[0012] Weak fire and water resistance: Cables are easily flammable in a fire and cannot withstand water spray, leading to electrical failure;

[0013] Severe electromagnetic interference: The shielding layer has high transfer impedance, which interferes with signal transmission;

[0014] Excessive outer diameter and weight: Poor wear resistance of the sheath material results in bulky cables that are difficult to deploy flexibly.

[0015] While existing technologies employ cross-linked polyethylene insulation and copper wire shielding, they still struggle to simultaneously meet the requirements for high mechanical strength, wide temperature range stability, fire and water resistance, and lightweight design. Therefore, there is an urgent need for a dedicated DC cable for energy storage systems with superior overall performance. Utility Model Content

[0016] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a DC cable for an energy storage system. This cable has excellent bending and tensile properties, as well as excellent electrical insulation properties, and can maintain stable insulation performance in both high and low temperature environments. At the same time, it is also fireproof, waterproof, resistant to damp heat, and has excellent flame retardant properties. Moreover, the cable is resistant to electromagnetic interference, ensuring the stability of signal transmission. In addition, the cable has a small outer diameter and is lightweight, which can meet the requirements of cable lightweighting and flexibility.

[0017] To achieve the above objectives, this utility model is implemented through the following technical solution:

[0018] The present invention provides a DC cable for an energy storage system, comprising: a conductor, wherein the conductor is sequentially wrapped with a composite isolation layer, an insulation layer, a spray-proof layer, a ceramicized protective layer, a metal fiber shielding layer, and a sheath layer; the conductor has a layered winding structure, and the winding pitch is 6 to 8 times the outer diameter of the conductor stranding.

[0019] In at least one embodiment, the conductor is a type 5 tin-plated soft copper conductor, with an aramid twisted rope as the conductor carrier core at the center; the layered winding structure is specifically a layered reverse winding structure of soft, fine tin-plated round copper wire.

[0020] In at least one embodiment, the composite isolation layer is composed of an overlap of polyester tape and lightweight non-woven fabric, with the overlap rate of the tape being 5% to 15% of the tape width.

[0021] In at least one embodiment, the insulating layer includes an inner insulating layer and an outer insulating layer, wherein the ratio of the inner insulating layer to the outer insulating layer is 1:4.

[0022] In at least one embodiment, the inner insulation layer is a cross-linked polyethylene inner insulation layer, and the outer insulation layer is a cross-linked polyolefin outer insulation layer.

[0023] In at least one embodiment, the anti-spray layer is specifically a ceramicized polyolefin anti-spray layer, which is extruded from ceramicized polyolefin material.

[0024] In at least one embodiment, the ceramicized protective layer is formed by two layers of ceramicized mica tape wrapped in reverse overlapping directions, the width of the ceramicized mica tape being 2.5 times the outer diameter of the cable wrapping, and the wrapping overlap rate being 30% to 40%.

[0025] In at least one embodiment, the metal fiber shielding layer is specifically a shielding structure woven from a mixture of fibers and tin-plated copper wires.

[0026] In at least one embodiment, the weaving density of the metal fiber shielding layer is 90%, and the weaving angle does not exceed 45°.

[0027] In at least one embodiment, the sheath layer is formed by extrusion of a highly elastic and wear-resistant TPU polyether-type polyurethane elastomer.

[0028] The beneficial effects of the above-described technical solution of this utility model are as follows:

[0029] 1) The present invention discloses a DC cable for an energy storage system, which has excellent bending and tensile properties, as well as excellent electrical insulation properties, and can ensure stable insulation performance in both high and low temperature environments; at the same time, it is also fireproof, waterproof, resistant to damp heat, and has excellent flame retardant properties; moreover, the cable is resistant to electromagnetic interference, ensuring the stability of signal transmission; in addition, the cable has a small outer diameter and light weight, which can meet the requirements of cable lightweighting and flexibility.

[0030] 2) The conductor winding pitch of the DC cable of the energy storage system of this utility model is controlled within 6 to 8 times the outer diameter of the conductor stranding in order to maintain the conductor's excellent flexibility. The adjacent layers adopt opposite directions, which can effectively reduce the electromagnetic induction between adjacent layers, and at the same time effectively reduce the stress concentration of the conductor, improve the conductor's bending resistance, and solve the problems of conductor outer diameter exceeding the standard and conductor's poor tensile strength.

[0031] 3) The composite isolation layer wrapping overlap rate of the DC cable of the energy storage system of this utility model is controlled at 10% of the wrapping width. This can prevent the loss of protection when bending due to the small overlap rate, and at the same time avoid the problem of the overall increase in the outer diameter of the product due to the large overlap rate.

[0032] 4) The inner insulation layer and outer insulation layer of the DC cable of the energy storage system of this utility model are designed with a 1:4 ratio, which can maintain the stability of electrical insulation performance and flame retardant performance.

[0033] 5) The double-layer ceramic mica tape of the ceramic protective layer of the DC cable of the energy storage system of this utility model has opposite wrapping directions, which can significantly improve the tension uniformity of the wrapping tape and keep the ceramic mica tape tightly attached.

[0034] 6) The metal shielding layer of the DC cable of the energy storage system of this utility model can effectively reduce the transfer impedance of the cable shielding layer and improve the cable shielding performance by controlling the braiding density and braiding angle. It can effectively avoid signal interference and electromagnetic coupling problems during signal transmission. At the same time, the addition of fiber yarn can effectively improve the tensile strength and tensile performance of the braided shielding layer. Attached Figure Description

[0035] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute an improper limitation of this utility model.

[0036] Figure 1 This is a cross-sectional schematic diagram of a DC cable for an energy storage system mentioned in Embodiment 1 of this utility model.

[0037] In the diagram: 1. Sheath layer; 2. Metal fiber shielding layer; 3. Ceramicized protective layer; 4. Spray-proof layer; 5. Outer insulation layer; 6. Inner insulation layer; 7. Conductor; 8. Composite isolation layer.

[0038] The distances or dimensions between parts have been exaggerated to show their positions; the diagram is for illustrative purposes only. Detailed Implementation

[0039] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0040] As described in the background section, the purpose of this utility model is to overcome the shortcomings of the prior art and provide a DC cable for an energy storage system. This cable has excellent bending and tensile properties, as well as excellent electrical insulation properties, and can maintain stable insulation performance in both high and low temperature environments. It is also fireproof, waterproof, and resistant to damp heat, with excellent flame retardant properties. Furthermore, the cable is resistant to electromagnetic interference, ensuring the stability of signal transmission. In addition, the cable has a small outer diameter and is lightweight, which can meet the requirements for lightweight and flexible cables.

[0041] Example 1

[0042] In a typical embodiment of this utility model, such as Figure 1 As shown, this embodiment discloses a DC cable for an energy storage system, comprising: a conductor 7, with a composite isolation layer 8, an insulation layer, a spray-resistant layer 4, a ceramicized protective layer 3, a metal fiber shielding layer 2, and a sheath layer 1 sequentially wrapped around the outside of the conductor 7. The conductor 7 has a layered winding structure, and the winding pitch is 6 to 8 times the outer diameter of the conductor 7 strand. By controlling the winding pitch of the conductor 7 within 6 to 8 times the outer diameter of the conductor 7 strand, the conductor 7 can maintain excellent flexibility.

[0043] In this embodiment, conductor 7 is a type 5 tin-plated soft copper conductor 7, with an aramid filament twisted rope as the conductor carrying core. Conductor 7 uses a reverse layered winding structure of soft, fine tin-plated round copper wire. The winding pitch of conductor 7 is controlled within 6 to 8 times the outer diameter of conductor 7 to maintain excellent flexibility. The reverse layered winding structure of conductor 7, with adjacent layers in opposite directions, can effectively reduce electromagnetic induction between adjacent layers, while also effectively reducing stress concentration in conductor 7 and improving its bending resistance. Furthermore, the use of aramid filament twisted rope as the conductor carrying core gives conductor 7 high tensile strength, effectively solving the problems of conductor 7's excessive outer diameter and poor tensile strength.

[0044] The conductor 7 is wrapped with a composite insulating layer 8, which is composed of overlapping polyester tape and lightweight non-woven fabric. The overlap rate of the tape wrapping is 5% to 15% of the tape width. In this embodiment, the overlap rate is preferably 10% of the tape width. The composite insulating layer 8 is composed of polyester tape and lightweight non-woven fabric. During extrusion insulation, the outer lightweight non-woven fabric of the composite insulating layer 8 can be adhered to the inner insulation layer. Increasing the composite insulating layer 8 allows for a certain gap between the conductor 7 and the insulation, giving the conductor 7 a range of free movement within the insulation, thus ensuring that the conductor 7 has a certain degree of flexibility. The polyester tape and lightweight non-woven fabric are wrapped in an overlapping manner, with the overlap rate controlled at 10% of the tape width. This prevents loss of protection during bending due to insufficient overlap, and also avoids an overall increase in the outer diameter of the product due to excessive overlap. The inner polyester tape of the composite insulating layer 8 helps to evenly distribute the stress on the conductor 7 when the cable is bent, preventing excessive stress from damaging the insulation layer.

[0045] The composite insulating layer 8 is surrounded by an insulating layer, which includes an inner insulating layer 6 and an outer insulating layer 5. To ensure the adhesion of the insulating layer in high-temperature (125℃) and low-temperature (-40℃) environments, the insulating layer in this embodiment is designed with a cross-linked polyethylene inner insulating layer with a temperature resistance of 125℃ to -40℃ and a cross-linked polyolefin outer insulating layer. The insulating layer is produced using a fully automated insulating extrusion process, equipped with an active take-up and untake-up device and an interlocking device to maintain uniform insulating extrusion during the process. It is equipped with a fully automated spark tester and a fully automated outer diameter measuring and control instrument, which automatically shuts down the machine to protect against defects during the extrusion process. In this embodiment, to maintain the stability of electrical insulation performance and flame retardant performance, the ratio of the inner insulating layer 6 to the outer insulating layer 5 is designed to be 1:4. A 1:4 ratio of inner and outer insulation provides optimal performance, simultaneously meeting electrical performance requirements and single-strand vertical combustion requirements. Furthermore, a segmented cooling method is used during production, with the first segment's water temperature controlled at 60℃ and the second segment at room temperature. The initial temperature of 60℃ allows the insulation layer to adhere better to conductor 7, resulting in improved adhesion. This addresses issues such as insufficient adhesion, easy cracking, and poor insulation stability under high and low temperature conditions. Furthermore, advanced irradiation crosslinking technology is employed after insulation extrusion, avoiding contact with moisture and the effects of high temperature and pressure during the crosslinking process. This effectively maintains the insulation and flame-retardant properties of the cable insulation. By designing an appropriate irradiation crosslinking dosage, excellent physical and mechanical properties are achieved while maintaining insulation and flame-retardant performance, thus meeting the required service life.

[0046] To ensure the cable can withstand both flames and water spray during a fire, a spray shield layer 4 is installed on the outside of the cable's insulation. This spray shield layer 4 is extruded from ceramicized polyolefin material. To maintain effective spray protection and vibration resistance, the spray shield layer 4 is designed to be 2mm thick, ensuring both protection against spray vibration and preventing an increase in the cable's outer diameter due to its design. During cable combustion, the ceramicized polyolefin spray shield layer forms a hard, round shell, effectively preventing the spread and propagation of flames and protecting the cable's internal structure from the fire. It maintains normal operation of the circuit even when flames persist. Furthermore, the shell prevents moisture from water spray systems from affecting the cable during a fire, preventing electrical accidents caused by moisture penetration, effectively solving the problem of weak fire and water resistance in traditional DC cables.

[0047] To prevent cracking or detachment of the ceramicized spray layer due to flame combustion under fire conditions, a ceramicized protective layer 3 is installed on the outside of the anti-spray layer 4. In this embodiment, the ceramicized protective layer 3 is a double-layer ceramicized mica protective layer, formed by overlapping and wrapping two layers of ceramicized mica tape. The width of the ceramicized mica tape is 2.5 times the outer diameter of the cable wrapping. To avoid electric flashover during wrapping, a reverse overlapping wrapping method is used. However, a low overlap rate will cause electric flashover, while a high overlap rate will result in material waste. Therefore, the overlap rate is controlled within the range of 30% to 40%. In this embodiment, the overlap rate is preferably 30%. The double-layer ceramicized mica tape is wrapped in opposite directions, which can significantly improve the tension uniformity of the wrapping tape and ensure that the ceramicized mica tape can be tightly adhered.

[0048] A metal fiber shielding layer 2 is set on the outside of the ceramicized protective layer 3. It adopts a mixed fiber and tinned copper wire braided shielding structure. In order to reduce the transfer impedance, the braided structure of the shielding layer is designed. The transfer impedance is reduced by selecting the braided single filaments and adjusting the braiding angle. The braiding density is controlled at 90% and the braiding angle is ≤45°. By controlling the braiding density and braiding angle, the transfer impedance of the cable shielding layer can be effectively reduced, the cable shielding performance can be improved, and the problems of signal interference and electromagnetic coupling during signal transmission can be effectively avoided. At the same time, the addition of fiber yarn also effectively improves the tensile strength and tensile properties of the braided shielding layer.

[0049] The outermost layer of the cable, namely the outermost layer of the metal fiber shielding layer 2, is the sheath layer 1, which is extruded from a high-elasticity, wear-resistant TPU polyether-type polyurethane elastomer. The outstanding characteristics of polyurethane thermoplastic elastomers are excellent wear resistance, excellent ozone resistance, high hardness, high strength, good elasticity, and low-temperature resistance. They also have good oil resistance, chemical resistance, and environmental resistance. In humid environments, the hydrolytic stability of polyether-type esters far exceeds that of polyester-type elastomers. Furthermore, polyurethane thermoplastic elastomers also possess advantages such as low-smoke, halogen-free material, flame retardancy, environmental friendliness, and resistance to battery acids and coolant corrosion, further enhancing the cable's environmental friendliness and stability. The TPU elastomer sheath structure is designed for extrusion. To improve the cable's roundness and further reduce the finished cable's outer diameter, the extrusion pressure is appropriately increased to maintain the overall stability and roundness of the cable.

[0050] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. An energy storage system DC cable, characterized by include: The conductor is surrounded by a composite isolation layer, an insulation layer, a spray-proof layer, a ceramicized protective layer, a metal fiber shielding layer, and a sheath layer in sequence on its outer side; the conductor has a layered winding structure, and the winding pitch is 6 to 8 times the outer diameter of the conductor strand.

2. The DC cable for an energy storage system as described in claim 1, characterized in that, The conductor is a Class 5 tin-plated soft copper conductor, with aramid yarn twisted rope as the conductor core at the center; the layered winding structure is specifically a layered reverse winding structure of soft, fine tin-plated round copper wire.

3. An energy storage system DC cable as claimed in claim 1, characterized in that, The composite isolation layer is composed of polyester tape and lightweight non-woven fabric wrapped together, with the tape overlap rate being 5% to 15% of the tape width.

4. An energy storage system DC cable as claimed in claim 1, characterized in that, The insulating layer includes an inner insulating layer and an outer insulating layer, and the structural ratio of the inner insulating layer to the outer insulating layer is 1:

4.

5. An energy storage system DC cable according to claim 4, wherein, The inner insulation layer is a cross-linked polyethylene inner insulation layer, and the outer insulation layer is a cross-linked polyolefin outer insulation layer.

6. An energy storage system DC cable according to claim 1, wherein, The anti-spray layer is specifically a ceramicized polyolefin anti-spray layer, which is extruded from ceramicized polyolefin material.

7. An energy storage system DC cable according to claim 1, wherein, The ceramicized protective layer is formed by two layers of ceramicized mica tape wrapped in opposite directions. The width of the ceramicized mica tape is 2.5 times the outer diameter of the cable wrapping, and the wrapping overlap rate is 30% to 40%.

8. An energy storage system DC cable according to claim 1, wherein, The metal fiber shielding layer is specifically a shielding structure woven from a mixture of fibers and tin-plated copper wires.

9. An energy storage system DC cable according to claim 8, c h a r a c t e r i z e d in that The metal fiber shielding layer has a weaving density of 90% and a weaving angle of no more than 45°.

10. An energy storage system DC cable as claimed in claim 1, characterized in that The sheath layer is made of high-elasticity, wear-resistant TPU polyether-type polyurethane elastomer extruded.

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