8-shaped weather-proof direct current cable for photovoltaic power generation inverter

Abstract

The utility model relates to cable technical field especially 8 -shaped weather -resistant direct current cable for photovoltaic power generation inverter, including main cable and pendant cable, the main cable includes the power cable that sets up mutually in parallel, pendant cable connection setting between two parallel power cables, one power cable, pendant cable, another power cable combination constitutes 8 -shaped weather -resistant direct current cable, the power cable outside is provided with the insulating sheath, the pendant cable presents H -shaped setting, and the upper and lower ends of pendant cable present outward curved arc shape setting, the upper and lower ends of pendant cable embed in corresponding power cable insulating sheath respectively, the cable structural strength of the utility model is high, and the service life is long.

Description

Technical Field

[0001] This utility model relates to the field of cable technology, specifically to a figure-eight weather-resistant DC cable for photovoltaic power generation inverters. Background Technology

[0002] Solar energy is one of the renewable, green, and clean energy sources, inexhaustible and readily available. Photovoltaic power generation, a practical technology that converts solar energy into electrical energy using the photovoltaic effect, is highly favored for its high quality, reliability, flexibility, long service life, and lack of environmental pollution, and has broad development prospects worldwide.

[0003] The cables used on solar panels require specialized photovoltaic cables with advantages such as high temperature resistance, cold resistance, oil resistance, acid and alkali resistance, UV protection, flame retardancy, environmental friendliness, and long service life. They are mainly used in harsh climatic conditions and have a service life of over 25 years. Currently, photovoltaic cables are often exposed to harsh environmental conditions, such as high temperature, low temperature, ultraviolet radiation, ozone, drastic temperature changes, chemical corrosion, and humid environments. At the same time, the cables must withstand pressure, bending, tension, cross tensile loads, and strong impacts. Under such harsh environmental stress, the cable sheath is easily damaged and absorbs water, which can decompose the cable insulation layer. All of these situations can directly cause certain losses to the cable system and increase the risk of cable short circuits. Utility Model Content

[0004] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide an 8-shaped weather-resistant DC cable for photovoltaic power generation inverters, which has the advantages of improving weather resistance and structural stability, and reducing sheath damage and short circuit risk.

[0005] To achieve the above objectives, this utility model provides the following technical solution: an 8-shaped weather-resistant DC cable for photovoltaic power generation inverters, comprising a main cable and a suspension cable. The main cable includes power cables arranged in parallel to each other. The suspension cable is connected and arranged between two parallel power cables. One power cable, the suspension cable, and the other power cable are combined to form an 8-shaped weather-resistant DC cable. The power cables are provided with an insulating sheath. The suspension cable is arranged in an I-shape, and the upper and lower ends of the suspension cable are arranged in an outwardly curved arc shape. The upper and lower ends of the suspension cable are respectively embedded in the insulating sheaths of the corresponding power cables.

[0006] In some embodiments, the power cable has a shielding layer one, an inner sheath, a shielding layer two, an insulating filler layer and a multi-core conductor arranged sequentially inside the insulating sheath.

[0007] In some embodiments, a pull wire is provided between the inner sheath and the second shielding layer, and the pull wire is located on the side away from the suspension cable.

[0008] In some embodiments, the second shielding layer and the insulating shielding layer are provided with recessed grooves corresponding to the pull wire.

[0009] In some embodiments, limit protrusions are symmetrically arranged on the upper and lower ends of the suspension cable on opposite surfaces.

[0010] In some embodiments, the middle vertical end portion of the suspension cable is covered with a protective layer, which is integrally formed with the insulating sheath.

[0011] In some embodiments, the shielding layer is an aluminum foil shielding layer.

[0012] In some embodiments, the second shielding layer is a metal woven mesh shielding layer.

[0013] Compared with the prior art, the beneficial effects of this utility model are: through the figure-eight structure formed by the main cable and the suspension cable and the I-shaped suspension cable design, and by enhancing mechanical strength and shielding layer layout, it effectively resists the stress of harsh environment, reduces the risk of sheath breakage and insulation layer decomposition, and has the advantages of improving weather resistance and structural stability, and reducing the risk of sheath damage and short circuit.

[0014] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. The embodiments of this application will provide a detailed description and understanding of the application. Attached Figure Description

[0015] Figure 1 This is a cross-sectional structural diagram of the present invention;

[0016] Figure 2 This is a schematic diagram of the cross-sectional structure of the power cable of this utility model;

[0017] Figure 3 This is a schematic diagram of the cross-sectional structure of the suspension cable of this utility model.

[0018] In the diagram: 1. Power cable; 2. Suspension cable; 3. Insulating sheath; 4. Shielding layer one; 5. Inner sheath; 6. Shielding layer two; 7. Insulating filler layer; 8. Multi-core conductor; 9. Pull wire; 10. Groove; 11. Limiting protrusion; 12. Protective layer. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0020] In traditional photovoltaic (PV) power generation systems, cables are constantly exposed to high and low temperatures, ultraviolet radiation, ozone, chemical corrosion, and humid environments. Under mechanical loads, the sheath is prone to cracking, leading to water absorption and decomposition of the insulation layer, significantly increasing the risk of short circuits in the cable system. For example, in outdoor scenarios of coastal PV power plants, cables must withstand cyclic thermal expansion and contraction stress caused by diurnal temperature variations, chemical corrosion from sea breezes carrying salt spray, and continuous tensile loads caused by the weight of the PV panels themselves. Due to the lack of radial restraint between I-beam support structures, microcracks develop at the sheath interface under alternating stress, allowing moisture to seep into the insulation filler layer along these cracks, reducing the dielectric strength. If these problems are not addressed, the rate of cable insulation degradation will accelerate, increasing system leakage current, leading to frequent partial discharge phenomena, ultimately resulting in abnormal power attenuation of the PV array. The PV power plant's operation and maintenance costs will increase significantly due to frequent cable replacements, and in extreme cases, it may trigger DC-side arcing faults, threatening the safe operation of the system.

[0021] Faced with the aforementioned problems, this application first analyzes that the root cause of cable sheath rupture lies in the lack of an effective mechanism for dispersing alternating stress in traditional structures. When the cable bears a continuous tensile load caused by the weight of the photovoltaic panel, the I-beam support structure is unable to constrain the radial displacement of the cable, leading to micro-cracks at the sheath interface. To address this, this application attempts to improve the overall cable structure by considering a parallel double-line layout to share the load and adding a connecting component between the two lines to form a closed force transmission path. Further research revealed that if the connecting component adopts an I-beam cross-section and is embedded in the cable sheath, it can achieve uniform stress distribution and prevent moisture from seeping in along the connection interface. By simulating the response of different connection structures to alternating stress, it was finally determined that the suspension cable 2 should be designed as an I-beam shape with rounded transitions at both ends, so that it can disperse concentrated stress through the rounded surface when under tension, while forming a sealed interface by embedding in the sheath.

[0022] In this regard, such as Figure 1-3 As shown, this application proposes an 8-shaped weather-resistant DC cable for a photovoltaic power generation inverter, including a main cable and a suspension cable 2. The main cable includes power cables 1 arranged in parallel with each other. The suspension cable 2 is connected between two parallel power cables 1. One power cable 1, the suspension cable 2, and the other power cable 1 are combined to form an 8-shaped weather-resistant DC cable. The power cables 1 are provided with an insulating sheath 3. The suspension cable 2 is arranged in an I-shape, and the upper and lower ends of the suspension cable 2 are arranged in an outwardly curved arc shape. The upper and lower ends of the suspension cable 2 are respectively embedded in the insulating sheath 3 of the corresponding power cables 1.

[0023] The main cable refers to the parallel power cables 1, which can be made of multi-core conductors 8 covered with insulation material. The parallel layout improves the overall structural stability of the cable and allows it to withstand complex environmental stresses. The suspension cable 2 is an I-shaped assembly connecting the two main cables, which can be molded from a highly elastic material. The I-shaped structure disperses external loads and enhances bending resistance. The insulating sheath 3 is the outer protective layer 12 surrounding the power cables 1, which can be made of cross-linked polyethylene material, preventing moisture penetration and resisting ultraviolet radiation and chemical corrosion. The arc-shaped design at both ends of the suspension cable 2 refers to the ends being bent and embedded into the main cable sheath, which can be achieved using a hot-melt injection molding process. The arc shape reduces stress concentration and prevents cracking at the connection between the suspension cable 2 and the main cable. The insertion of the suspension cable 2 ends into the insulating sheath 3 refers to a physical fixed connection, which can be achieved by pre-forming the sheath and then injection molding it over the ends of the suspension cable 2. This embedded design prevents the suspension cable 2 from separating from the main cable due to external forces.

[0024] The core innovation of this application lies in the figure-eight integrated structure design of the main cable and the I-beam suspension cable 2, which significantly improves the weather resistance and mechanical strength while maintaining the cable's conductivity, thereby solving the technical problems of cable sheath damage and insulation layer decomposition in harsh environments.

[0025] The working process and principle of this application are as follows: the figure-eight weather-resistant DC cable for photovoltaic power generation inverters includes a main cable and a suspension cable 2. The main cable consists of two parallel power cables 1, each with an external insulating sheath 3. The suspension cable 2 connects the two parallel power cables 1 in an I-shape. The upper and lower ends of the suspension cable 2 are bent outward into arcs and embedded in the insulating sheath 3 of the corresponding power cable 1. This structure forms an overall figure-eight shape.

[0026] The design of the I-beam suspension cable 2 allows it to effectively disperse and transfer stress. When the cable is subjected to tensile loads, the I-beam structure of the suspension cable 2 can evenly distribute stress and avoid stress concentration. The arc-shaped design at both ends further optimizes stress distribution and reduces stress concentration points. The design of embedding the power cable 1 sheath at the end of the suspension cable 2 forms a sealed interface, effectively preventing moisture from seeping in along the connection.

[0027] This figure-eight structure allows the two power cables 1 to share the load, significantly reducing the stress on a single cable compared to a single cable bearing the entire load. Simultaneously, the presence of the suspension cable 2 restricts the radial displacement of the cable, improving the overall structural stability.

[0028] As a preferred embodiment, the solution of this application is implemented as follows: The figure-eight weather-resistant DC cable for photovoltaic power generation inverters consists of two parallel power cables 1 and a suspension cable 2 connecting them. The power cables 1 are externally fitted with weather-resistant insulating sheaths 3, the material of which can be a polymer resistant to ultraviolet radiation and ozone. The suspension cable 2 adopts an I-shaped cross-section design, with its upper and lower ends bent outwards into arc shapes. The radius of curvature of the arcs can be optimized according to the actual application scenario and load conditions. The upper and lower ends of the suspension cable 2 are respectively embedded in the insulating sheaths 3 of the corresponding power cables 1, with an embedding depth sufficient to form an effective sealing interface.

[0029] In practical applications, this figure-eight cable can be connected to the supporting structure via the middle of the suspension cable 2, with the two power cables 1 connected to the photovoltaic panel and the inverter, respectively. When the cable bears the tensile load caused by the weight of the photovoltaic panel, the load is evenly distributed to the two power cables 1 via the suspension cable 2. The I-shaped structure and rounded ends of the suspension cable 2 effectively disperse stress and prevent sheath breakage caused by stress concentration. At the same time, the embedded connection between the suspension cable 2 and the sheath of the power cable 1 prevents moisture from seeping in along the interface.

[0030] Through the above solutions, this application effectively solves the problems of sheath cracking and insulation layer decomposition caused by water absorption in traditional photovoltaic cables under harsh environments. The figure-eight structure ensures uniform load distribution and reduces stress on individual cables. The design of the I-beam suspension cable 2 optimizes stress distribution and reduces the risk of sheath cracking. The embedded connection between the suspension cable 2 and the sheath forms a sealed interface, effectively preventing moisture infiltration. These designs collectively improve the cable's weather resistance and service life, reducing maintenance costs and safety risks of photovoltaic systems.

[0031] In some of the solutions described above in this application, the simple internal structure of the power cable 1 insulation sheath 3 results in insufficient electromagnetic interference resistance, and the lack of layered protection design makes the internal conductors susceptible to mechanical stress damage.

[0032] This application further proposes that the insulating sheath 3 of the power cable 1 is provided with a shielding layer 4, an inner sheath 5, a second shielding layer 6, an insulating filling layer 7, and a multi-core conductor 8 in sequence.

[0033] The shielding layer 4 is made of aluminum foil and forms a continuous electromagnetic isolation layer. The inner sheath 5 is formed by extrusion molding and covers the outer surface of the shielding layer 4 to form a rigid support structure. The shielding layer 6 is made of metal braided mesh that wraps around the outer periphery of the inner sheath 5, with the warp and weft threads of the braided mesh forming a mesh-like tensile layer. The insulating filling layer 7 is injection molded from elastic polymer material, covering and fixing the multi-core conductor 8 at the axial center position. The shielding layer 4 and the shielding layer 6 form a double-layer electromagnetic shielding. The inner sheath 5 acts as a rigid skeleton to support the shielding layer 6, and the insulating filling layer 7 absorbs the vibration energy of the conductor.

[0034] Specifically, the aluminum foil shielding layer 4 blocks external electromagnetic interference from entering the conductor area by wrapping the cable around its entire circumference. The inner sheath 5 is made of high-density polyethylene, with its wall thickness controlled between 0.8-1.2 mm using a die, providing a smooth surface for the outer shielding layer 6. The metal braided mesh of the shielding layer 6 forms a flexible tensile layer with copper wire diameters of 0.12 mm and a braiding density of 85%, releasing stress through mesh deformation when the cable is bent. The insulating filler layer 7 is made of EPDM rubber, injection molded to a Shore hardness of 60, evenly separating and fixing seven copper conductors with a cross-section of 0.75 square millimeters. When the cable is subjected to external impact, the shielding layer 6 disperses the impact energy through the deformation of the braided mesh, the inner sheath 5 maintains the spatial position of the conductors, and the insulating filler layer 7 buffers conductor displacement, thereby achieving synergistic enhancement of electromagnetic and mechanical protection.

[0035] As a preferred embodiment, the solution of this application is specifically implemented as follows:

[0036] The power cable 1 has an insulating sheath 3 containing, in sequence, a first shielding layer 4, an inner sheath 5, a second shielding layer 6, an insulating filler layer 7, and a multi-core conductor 8. The first shielding layer 4 is made of aluminum foil, the inner sheath 5 is made of polyethylene, the second shielding layer 6 is made of metal braided mesh, the insulating filler layer 7 is made of cross-linked polyethylene, and the multi-core conductor 8 is made of copper wire. Specifically, the first shielding layer 4 has a thickness of 0.1 mm, the inner sheath 5 has a thickness of 1 mm, the second shielding layer 6 has a thickness of 0.5 mm, and the insulating filler layer 7 has a thickness of 2 mm. The multi-core conductor 8 includes four single-core wires, each with a cross-sectional area of ​​4 mm².

[0037] Through the above technical solution, this application achieves multi-layer protection for the power cable 1. Shielding layer 4 and shielding layer 6 together form a double-layer shielding structure, effectively reducing electromagnetic interference. The inner sheath 5 and the insulating filler layer 7 provide additional insulation protection, enhancing the cable's withstand voltage. The design of the multi-core conductor 8 increases the cable's current carrying capacity. Therefore, the overall performance of the cable is significantly improved, adapting to the harsh environmental conditions in photovoltaic power generation systems and extending the cable's service life.

[0038] In some of the solutions described above in this application, the positional relationship between the pull wire 9 and the inner sheath 5 and the shielding layer 6 may lead to stress concentration or structural instability, affecting the overall durability of the cable when subjected to cross tensile loads, and thus shortening the service life of the cable in harsh environments.

[0039] This application further proposes that a pull wire 9 is provided between the inner sheath 5 and the second shielding layer 6, and the pull wire 9 is located on the side away from the suspension cable 2.

[0040] The pull wire 9 is located in the interlayer area between the inner sheath 5 and the second shielding layer 6, with its axis parallel to the extension direction of the power cable 1. A groove 10 is formed at the corresponding position of the second shielding layer 6 and the insulating shielding layer. The groove 10 has a depth of 0.5-1.2 mm and a width that forms a clearance fit with the diameter of the pull wire 9. The pull wire 9 is mechanically connected to the inner sheath 5 and the second shielding layer 6 through a hot-pressing process. Its material is high-density polyethylene with a tensile strength ≥500 MPa.

[0041] Specifically, the guy wire 9 extends longitudinally at a lateral position away from the suspension cable 2, forming a support structure independent of the suspension cable 2 through the positioning constraint of the embedded groove 10. When the cable is subjected to lateral tensile load, the guy wire 9 shares the longitudinal stress acting on the second shielding layer 6, reducing the interlayer shear force between the inner sheath 5 and the second shielding layer 6. The fit gap between the embedded groove 10 and the guy wire 9 is controlled within the range of 0.05-0.15mm, which allows for thermal expansion and contraction deformation while limiting the displacement of the guy wire 9. This structure allows the second shielding layer 6 to maintain its planar shape under tension, avoiding damage to the insulation filling layer 7 due to local wrinkles.

[0042] As a preferred embodiment, the solution of this application is implemented as follows: A pull wire 9 is provided between the inner sheath 5 and the second shielding layer 6. The pull wire 9 is located on the side away from the suspension cable 2. The pull wire 9 can be made of high-strength fiber material, such as aramid fiber or carbon fiber. The pull wire 9 extends along the length of the cable and fits tightly against the inner sheath 5 and the second shielding layer 6. The cross-section of the pull wire 9 can be circular or flat. The number of pull wires 9 can be set according to actual needs, for example, 1-3 wires can be set. The diameter of the pull wire 9 can be selected in the range of 0.5-2mm. The position of the pull wire 9 can be selected in the range of 45°-90° angle between the contact surface of the inner sheath 5 and the second shielding layer 6.

[0043] Through the above technical solutions, this application improves the tensile strength and mechanical properties of the cable. The installation of the guy wire 9 enhances the overall stability of the cable structure and reduces deformation and damage to the cable during use. The guy wire 9 is located on the side away from the suspension cable 2, which balances the force on the cable and prevents twisting or deformation when the cable is suspended. Furthermore, the presence of the guy wire 9 provides additional traction points during cable installation and maintenance, facilitating cable laying and handling.

[0044] In some of the above-mentioned solutions of this application, when the guy wire 9 is set on the side away from the suspension cable 2, the contact surface between the guy wire 9 and the shielding layer 6 and the insulating shielding layer is prone to friction or displacement due to stress concentration, which can damage the shielding layer structure and affect the stability of the shielding effect.

[0045] This application further proposes that the shielding layer 6 and the insulating shielding layer are provided with embedded grooves 10 corresponding to the pull wire 9.

[0046] The shape of the recessed groove 10 matches the outer contour of the pull wire 9. The depth of the groove 10 is 1 / 3 to 1 / 2 of the diameter of the pull wire 9, and the width of the groove 10 is 0.5-1 mm larger than the diameter of the pull wire 9. The shielding layer 6 is made of metal braided mesh, and the insulating shielding layer is made of polymer composite material. Both have grooves 10 simultaneously opened at corresponding positions on the pull wire 9. After the pull wire 9 is embedded in the groove 10, the inner wall of the groove 10 forms surface contact with the surface of the pull wire 9, and the opening edge of the groove 10 is fixed to the surface of the pull wire 9 by a hot pressing process.

[0047] Specifically, during installation of the pull wire 9, it is embedded into the groove 10 along a predetermined path between the inner sheath 5 and the shielding layer 6. The depth design of the groove 10 restricts the radial displacement of the pull wire 9 while allowing for axial expansion and contraction. The hot-pressing fixation of the opening edge of the groove 10 forms a mechanical locking structure to prevent the pull wire 9 from slipping when the cable is bent. The edges of the groove 10 of the metal braided mesh shielding layer are covered to prevent the metal wires from piercing the insulation layer. This structure creates a stable contact interface between the pull wire 9 and the shielding layer. When subjected to cross tensile loads, stress is evenly transferred to the shielding layer through the groove 10, preventing local stress concentration that could lead to tearing of the shielding layer. When the cable is in a humid and hot environment, the fixing effect of the groove 10 prevents gaps from forming between the shielding layer and the pull wire 9, maintaining continuous shielding coverage and ensuring stable electromagnetic shielding performance.

[0048] As a preferred embodiment, the solution of this application is implemented as follows: The second shielding layer 6 and the insulating shielding layer are provided with recessed grooves 10 corresponding to the pull wire 9. Specifically, inside the insulating sheath 3 of the power cable 1, recessed grooves 10 corresponding to the pull wire 9 are provided on the second shielding layer 6 and the insulating shielding layer. These grooves 10 extend along the direction of the pull wire 9, forming a channel to accommodate the pull wire 9. The depth and width of the grooves 10 are designed according to the size of the pull wire 9 to ensure that the pull wire 9 can be securely embedded therein. For example, the groove 10 can have a semi-circular or rectangular cross-section, with a width slightly larger than the diameter of the pull wire 9 and a depth of approximately half to two-thirds of the diameter of the pull wire 9. This design allows the pull wire 9 to fit tightly against the second shielding layer 6 and the insulating shielding layer, preventing loosening or displacement inside the cable.

[0049] Through the above technical solutions, this application improves the stability of the pull wire 9 within the cable, preventing displacement or deformation during use. Simultaneously, the embedded groove 10 design allows for tighter contact between the pull wire 9 and the shielding layer 6 and the insulating shielding layer, enhancing the overall structural strength of the cable. Furthermore, this design reduces interference from the pull wire 9 to other internal components, ensuring the integrity of the cable's internal structure and the normal function of each component. Consequently, the cable's service life is extended, and its reliability in harsh environments is improved.

[0050] In some of the solutions described above in this application, when the connection point between the suspension cable 2 and the power cable 1 is subjected to cross-tension or impact loads, there is a risk of relative displacement due to insufficient friction of the contact surface, which may cause damage or detachment of the sheath structure.

[0051] This application further proposes that the upper and lower ends of the suspension cable 2 are symmetrically provided with limit protrusions 11 on their opposite surfaces.

[0052] The limiting protrusion 11 extends longitudinally along the end of the suspension cable 2, and its cross-section is trapezoidal or semi-circular. The limiting protrusion 11 and the pre-fabricated limiting groove inside the insulation sheath 3 of the power cable 1 form an interference fit, creating a mechanical interlocking structure. Furthermore, the symmetrically distributed limiting protrusions 11 can balance the stress distribution on both sides, avoiding deflection deformation caused by unilateral force. For example, the height of the limiting protrusion 11 is controlled within the range of 0.5-1.2mm, ensuring the fitting depth without damaging the sheath material.

[0053] Specifically, during the installation of the cable 2, the limiting protrusion 11 at its end is pressed into the corresponding groove 10 of the insulating sheath 3 of the power cable 1. When the cable is subjected to lateral tension, the limiting protrusion 11 and the sheath material are laterally compressed, absorbing energy through the elastic deformation of the material. Under vertical load, the symmetrically arranged limiting protrusions 11 simultaneously bear the pressure, preventing rotational displacement at the end of the cable 2. This structure creates a stable three-dimensional constraint between the cable 2 and the power cable 1, maintaining connection reliability while allowing necessary elastic deformation to accommodate dimensional fluctuations caused by temperature changes.

[0054] As a preferred embodiment, the solution of this application is specifically implemented as follows:

[0055] The upper and lower ends of the suspension cable 2 are symmetrically provided with limiting protrusions 11. The limiting protrusions 11 can be made of the same material as the suspension cable 2 and are integrally formed by molding or extrusion. The shape of the limiting protrusions 11 can be elongated, with its length direction parallel to the length direction of the suspension cable 2. The cross-section of the limiting protrusions 11 can be rectangular, semi-circular, or triangular. The height of the limiting protrusions 11 can be adjusted according to actual needs to ensure that it can effectively restrict the movement of the suspension cable 2 within the insulation sheath 3 of the power cable 1.

[0056] Through the above technical solution, this application can effectively prevent the lifting cable 2 from detaching from the insulation sheath 3 of the power cable 1. The setting of the limiting protrusion 11 increases the contact area between the lifting cable 2 and the insulation sheath 3 of the power cable 1, improving the stability of the lifting cable 2 within the insulation sheath 3 of the power cable 1. This structural design makes the figure-eight weather-resistant DC cable more reliable when used in harsh environments, reduces the risk of cable damage, and extends the service life of the cable.

[0057] In some of the above-mentioned solutions of this application, when the middle vertical end of the suspension cable 2 is subjected to pressure, bending, tension and cross tensile loads for a long time, its external structure is prone to wear or breakage due to mechanical stress concentration, resulting in a decrease in the overall structural stability of the cable.

[0058] This application further proposes that the middle vertical end of the suspension cable 2 is covered with a protective layer 12, which is integrally formed with the insulating sheath 3.

[0059] The protective layer 12 is formed using the same weather-resistant material as the insulating sheath 3 through a co-extrusion process, covering the vertical end surface of the suspension cable 2. The thickness of the protective layer 12 is set to 0.5-1.2mm, and a smooth curved surface is formed in the transition area where the suspension cable 2 connects to the main cable. A reinforcing fiber layer connected to the insulating sheath 3 is pre-embedded inside the protective layer 12. The fiber layer is woven from polyester material, and the fiber diameter is controlled within the range of 0.05-0.1mm.

[0060] Specifically, during cable laying, the bending stress borne by the middle of the suspension cable 2 is evenly distributed to the insulating sheath 3 through the protective layer 12. When the cable is subjected to external impact, the interface between the protective layer 12 and the insulating sheath 3, through the interpenetrating molecular chain structure formed by co-extrusion molding, effectively prevents interlayer delamination. The reinforcing fiber layer undergoes directional alignment under tensile load, converting axial stress into internal shear force. The curved transition design of the protective layer 12 reduces the stress concentration factor to below 1.2, and no cracks appeared after 5000 bending tests. This structure enables the cable to maintain structural integrity within a temperature range of -40℃ to 120℃, and increases the tensile strength to over 18MPa.

[0061] As a preferred embodiment, the solution of this application is implemented as follows: A protective layer 12 is wrapped around the middle vertical end of the suspension cable 2, and the protective layer 12 is integrally formed with the insulating sheath 3. Specifically, a protective layer 12 is extruded over the middle vertical end of the suspension cable 2. This protective layer 12 and the insulating sheath 3 of the power cable 1 are made of the same material and are formed into an integral structure by heat fusion during the manufacturing process. For example, the protective layer 12 can be made of polyvinyl chloride (PVC) material with a thickness of 1-2 mm. The length of the protective layer 12 can be adjusted according to actual needs, and it usually covers 50%-80% of the middle vertical section of the suspension cable 2.

[0062] Through the above technical solutions, this application improves the mechanical strength and weather resistance of the middle part of the suspension cable 2. Therefore, the suspension cable 2 can better withstand external forces in harsh environments, reducing the risk of breakage and damage. Furthermore, the protective layer 12 and the insulating sheath 3 are integrally formed, enhancing the stability and sealing of the overall structure and effectively preventing moisture and impurities from entering the cable.

[0063] In some of the above-mentioned schemes of this application, the insulating sheath 3 of the power cable 1 is provided with a shielding layer 4, an inner sheath 5, a second shielding layer 6, an insulating filling layer 7, and a multi-core conductor 8 in sequence. The shielding layer 4 serves as the first layer of electromagnetic interference protection inside the cable. Under conditions of high temperature, high humidity, or strong ultraviolet radiation, the shielding effectiveness may decrease or the mechanical properties may deteriorate due to improper material selection, thereby affecting the overall stability of the cable.

[0064] This application further proposes that the shielding layer 4 is an aluminum foil shielding layer.

[0065] The aluminum foil shielding layer is formed by extending metallic aluminum material to create a continuous, thin-layer structure that wraps around the outside of the multi-core conductor 8 and adheres to the inner sheath 5. The aluminum foil thickness is controlled within the range of 0.05-0.15 mm, with a longitudinal overlap rate of no less than 20%. The aluminum foil layer and the inner sheath 5 are bonded together using hot melt adhesive, and the joints are maintained with a spiral winding method to ensure continuous coverage. The surface of the aluminum foil layer is anodized to form an aluminum oxide layer with a thickness of 5-10 micrometers.

[0066] Specifically, the aluminum foil shielding layer forms an electromagnetic shielding interface through its metallic conductivity during cable operation, effectively blocking the outward radiation of electromagnetic fields generated inside the conductor. The alumina layer enhances the corrosion resistance of the aluminum foil surface, maintaining stable shielding effectiveness even when the photovoltaic system is exposed to humid and salt spray environments for extended periods. The ductility of aluminum allows the shielding layer to undergo plastic deformation rather than brittle fracture when the cable is bent. When the cable is subjected to cross tensile loads, the adhesive interface between the shielding layer and the inner sheath 5 buffers stress through the elastic deformation of the adhesive layer, preventing interlayer delamination. The longitudinal overlapping structure of the aluminum foil shielding layer provides deformation margin when the cable is heated, preventing cracking of the shielding layer due to thermal expansion and contraction, thereby ensuring the shielding integrity of the cable within the operating temperature range of -40℃ to 120℃.

[0067] As a preferred embodiment, the solution of this application is specifically implemented as follows: Shielding layer 4 is made of aluminum foil. The aluminum foil shielding layer is composed of multiple layers of thin aluminum foil, each layer having a thickness of 0.01 mm to 0.05 mm. The aluminum foil shielding layer is wrapped around the outside of the inner sheath 5 by winding or wrapping. A layer of conductive adhesive can be coated on the surface of the aluminum foil shielding layer to enhance the shielding effect.

[0068] Through the above technical solution, this application improves the electromagnetic shielding performance of the cable and reduces electromagnetic interference. The aluminum foil shielding layer has good conductivity and reflectivity, which can effectively block external electromagnetic wave interference and protect the signal quality transmitted by the internal conductors. At the same time, the aluminum foil shielding layer is lightweight, low in cost, easy to process and install, and improves the overall performance and service life of the cable.

[0069] In some of the schemes described above in this application, the material selection for shielding layer 6 is crucial to the reliability of the cable under complex mechanical stress. Conventional shielding structures are prone to breakage or deformation when subjected to bending, tension, or impact over a long period of time, leading to a decrease in shielding performance and thus increasing the risk of cable short circuits.

[0070] This application further proposes that the second shielding layer 6 adopts a metal braided mesh shielding layer.

[0071] The metal braided mesh shielding layer is woven from multiple strands of metal wire in a warp and weft interlacing manner. The metal braided mesh covers the outside of the inner sheath 5 and is tightly fitted to the insulating filler layer 7. The multiple strands of metal wire can be copper wire, tinned copper wire, or aluminum alloy wire, with a single wire diameter controlled within the range of 0.08-0.15mm. The mesh count is set to 80-120 meshes, and the weaving angle is maintained at 45°-60°. This braided mesh forms a continuous tubular structure when extending along the cable axis, possessing elastic shrinkage characteristics in the radial direction.

[0072] Specifically, the metal braided mesh, through its unique mesh structure, generates a uniform stress distribution when the cable is under stress. When the cable is subjected to bending loads, the metal wires at each node of the braided mesh slide to adjust their relative positions, avoiding localized stress concentration. Under axial tension, the braided mesh utilizes the frictional resistance between the metal wires to create a self-locking effect, limiting the amount of tensile deformation. The porous structure of the braided mesh allows the insulation filler material to undergo slight deformation during thermal expansion and contraction without damaging the interlayer bonding. This structural design ensures that the shielding layer maintains a complete conductive path under frequent mechanical loads, effectively suppressing electromagnetic interference. For example, when using 96-mesh tin-plated copper wire braided mesh, tests have shown that it can withstand more than 5000 90° reciprocating bends without wire breakage.

[0073] As a preferred embodiment, the solution of this application is specifically implemented as follows: the second shielding layer 6 is configured as a hexagonal twisted mesh structure woven from tin-plated copper wire. This metal woven mesh fully covers the outer surface of the inner sheath 5 circumferentially, and the weaving density is set to no less than 80 meshes per square centimeter. The diameter of the copper wires in the woven mesh is controlled within the range of 0.12-0.15 mm, the thickness of the woven layer is set to 0.25 mm, and the weaving angle is maintained at a 45-degree angle of cross-twisting. The ends of the woven mesh are ultrasonically welded to form a continuous closed loop structure.

[0074] Through the above technical solution, this application utilizes a continuous electromagnetic shielding layer formed by a high-density metal braided mesh. When the cable is subjected to bending stress, the mechanical load is dispersed by the deformation of the mesh. At the same time, in a high-temperature environment, the difference in thermal expansion of materials is compensated by the ductility of the metal. Thus, high-frequency harmonic interference is effectively suppressed in the complex electromagnetic environment of the photovoltaic system, and the distortion of the inverter output current caused by electromagnetic coupling is avoided.

[0075] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

[0076] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A figure-eight weather-resistant DC cable for photovoltaic power generation inverters, characterized in that: The cable includes a main cable and a suspension cable. The main cable includes power cables arranged in parallel to each other. The suspension cable is connected between the two parallel power cables. One power cable, the suspension cable, and the other power cable are combined to form an 8-shaped weather-resistant DC cable. The power cables are provided with an insulating sheath. The suspension cable is arranged in an I-shape, and the upper and lower ends of the suspension cable are arranged in an outward curved arc shape. The upper and lower ends of the suspension cable are respectively embedded in the insulating sheath of the corresponding power cable.

2. The figure-eight weather-resistant DC cable for a photovoltaic inverter according to claim 1, characterized in that: The power cable has a shielding layer 1, an inner sheath, a shielding layer 2, an insulating filling layer, and a multi-core conductor arranged sequentially inside its insulating sheath.

3. The figure-eight weather-resistant DC cable for a photovoltaic inverter according to claim 2, characterized in that: A pull wire is provided between the inner sheath and the second shielding layer, and the pull wire is located on the side away from the suspension cable.

4. The figure-eight weather-resistant DC cable for a photovoltaic inverter according to claim 3, characterized in that: The second shielding layer and the insulating shielding layer are provided with embedded grooves corresponding to the pull wire.

5. The figure-eight weather-resistant DC cable for a photovoltaic inverter according to claim 1, characterized in that: Limiting protrusions are symmetrically arranged on the upper and lower ends of the suspension cable.

6. The figure-eight weather-resistant DC cable for a photovoltaic inverter according to claim 5, characterized in that: The vertical end of the suspension cable is covered with a protective layer, which is integrally formed with the insulating sheath.

7. The figure-eight weather-resistant DC cable for a photovoltaic inverter according to claim 2, characterized in that: The shielding layer is an aluminum foil shielding layer.

8. The figure-eight weather-resistant DC cable for a photovoltaic inverter according to claim 2, characterized in that: The second shielding layer is a metal woven mesh shielding layer.

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