A copper-aluminum DC transmission busbar structure

Abstract

This utility model discloses a copper-aluminum DC transmission busbar structure, including a positive busbar, a negative busbar, a positive busbar insulation layer, a negative busbar insulation layer, and an outer insulation layer. The positive busbar and negative busbar each have a longitudinally extending internal cooling water channel. The positive and negative busbars are tightly wrapped with their respective insulation layers. The positive and negative busbar insulation layers are placed side-by-side, tightly against each other. The outer insulation layer completely covers and fixes the side-by-side positive and negative busbars. This utility model integrates the heat dissipation channels within the busbars and uses the outer insulation layer to provide a closed circumferential constraint against electromagnetic repulsion, resulting in a compact structure.

Description

Technical Field

[0001] This utility model relates to the field of high-current DC power transmission technology, specifically to a high-current copper-aluminum DC transmission busbar structure applied to magnetic confinement nuclear fusion devices. Background Technology

[0002] In magnetic confinement fusion devices, the superconducting magnet system requires a large DC power supply to provide tens to hundreds of thousands of amperes of steady-state DC current through transmission buses. Taking a tokamak device as an example, the power supply buses of its poloidal and longitudinal field coils continuously carry ultra-large currents during operation, which raises two core engineering problems: Joule heat accumulation caused by conductor resistance, and electromagnetic repulsion caused by reverse currents between adjacent conductors.

[0003] In existing technologies, high-current transmission busbars generally use aluminum or copper as the conductive substrate and are equipped with independent cooling devices on the outside. These cooling devices are typically metal water-cooled jackets wrapped around the outer surface of the busbar, with cooling water flowing through them to remove heat conducted from the busbar surface. The heat transfer path in this cooling method sequentially passes through the busbar body, the oxide layer on the busbar surface, the thermally conductive interface filling material, and the inner wall of the water-cooled jacket. The cumulative thermal resistance at each interface results in a large total thermal resistance, a significant internal temperature gradient within the busbar, and difficulty in effectively eliminating local hot spots through external cooling. When the current level increases to above 70kA, the Joule heat power density increases sharply with the square of the current, making it difficult for existing external cooling methods to control the maximum conductor temperature below the long-term allowable temperature of the insulating material. The external cooling device and its associated piping are also large, resulting in a loose structure and increased footprint for the entire busbar system. In the context of limited space and complex magnetic field environments in the tokamak hall of a fusion device, this increased footprint encroaches on the installation space of other critical components, and the relative positional shift between the busbar system and the magnetic field coils may introduce additional electromagnetic disturbances.

[0004] Current technologies address electromagnetic repulsion by adding metal reinforcement blocks and specialized clamps to the outside of the busbar. Taking the upgraded version of the National Spherical Toroidal Experiment (NSTX-U) as an example, its poloidal busbar and coil leads experience strong electromagnetic forces in the vertical direction when energized. Finite element stress analysis revealed excessive stress at the busbar connections, necessitating the addition of stainless steel reinforcement blocks and clamps to meet operational requirements. However, adding metal reinforcements presents several drawbacks. The metal reinforcements themselves generate eddy currents in the alternating magnetic field, introducing additional thermal loads. The connection between the reinforcements and the busbar via bolts or welding is prone to fatigue and loosening after prolonged exposure to alternating electromagnetic forces, requiring periodic shutdowns for tightening and maintenance. Furthermore, the reinforcements further increase the overall dimensions and number of components of the busbar system, contradicting the design goals of compactness and high reliability in fusion devices.

[0005] Existing high-current DC transmission buses face a range of technical challenges under high-current conditions, including insufficient heat dissipation efficiency, redundant electromagnetic constraint structures, and excessive system footprint. Utility Model Content

[0006] The purpose of this utility model is to provide a copper-aluminum DC transmission busbar structure to solve the technical problems of existing high-current DC transmission busbars, such as loose structure, large footprint, and insufficient long-term operational reliability caused by Joule heat accumulation and electromagnetic repulsion under current conditions of 70kA and above.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: A copper-aluminum DC transmission busbar structure includes a positive busbar, a negative busbar, a positive busbar insulation layer, a negative busbar insulation layer, and an external insulation layer; The positive busbar has a cooling water channel running through it along its length, and the negative busbar has a cooling water channel running through it along its length. The positive busbar insulation layer tightly covers the outer surface of the positive busbar, and the negative busbar insulation layer tightly covers the outer surface of the negative busbar; The positive busbar covered with the insulation layer of the positive busbar and the negative busbar covered with the insulation layer of the negative busbar are placed side by side and close together; The external insulation layer completely covers and fixes the positive and negative busbars placed side by side, and there is no gap between the external insulation layer and the insulation layer of the positive busbar, and between the external insulation layer and the insulation layer of the negative busbar.

[0008] Furthermore, the positive busbar and the negative busbar are made of aluminum or copper.

[0009] Furthermore, the positive busbar and the negative busbar are made of 6063-T6 aluminum alloy.

[0010] Furthermore, the positive busbar and the negative busbar are made of T2 copper.

[0011] Furthermore, the cross-sectional width of the positive busbar is 120mm to 600mm and the thickness is 60mm to 300mm; the cross-sectional width of the negative busbar is 120mm to 600mm and the thickness is 60mm to 300mm.

[0012] Furthermore, the diameters of the cooling water channels in the positive and negative busbars are predetermined based on the current load and heat dissipation conditions, and the axis of the cooling water channel in the positive busbar is located at the geometric center of the cross-section of the positive busbar, and the axis of the cooling water channel in the negative busbar is located at the geometric center of the cross-section of the negative busbar.

[0013] Furthermore, multiple cooling water channels are uniformly opened inside the positive busbar along the width direction, and multiple cooling water channels are uniformly opened inside the negative busbar along the width direction.

[0014] Furthermore, the positive busbar insulation layer, the negative busbar insulation layer, and the outer insulation layer are all molded from fiber-reinforced resin-based composite materials.

[0015] Furthermore, the fiber-reinforced resin-based composite material is an epoxy resin-based glass fiber composite material.

[0016] Furthermore, the outer insulation layer is manufactured using a continuous fiber circumferential winding molding process, and the fiber volume content of the winding layer is not less than 60%.

[0017] Furthermore, after the external insulation layer is cured, it forms a closed circumferential constraint structure on the outside of the positive busbar and the negative busbar assembly.

[0018] Furthermore, the external insulation layer is a pre-formed fiber-reinforced resin-based composite split-shell structure. The split-shell structure consists of two half-shells. The inner cavity shape of the two half-shells matches the outer contour of the positive and negative busbar assemblies placed side by side. The two half-shells are fastened to the outside of the positive and negative busbar assemblies and then secured by fastening straps.

[0019] Furthermore, the cooling water channel inside the positive electrode busbar is integrally formed with the positive electrode busbar through a hot extrusion process, and the cooling water channel inside the negative electrode busbar is integrally formed with the negative electrode busbar through a hot extrusion process.

[0020] Compared with the prior art, the present invention has the following beneficial effects: This invention integrates cooling water channels directly into the interior of the positive and negative busbars, eliminating the need for external independent water-cooling components and merging the heat dissipation structure with the conductive body. The flowing cooling medium within the internal channels directly absorbs the Joule heat generated by the busbar's resistance, resulting in a short heat transfer path and zero interfacial thermal resistance. This effectively controls conductor temperature rise, enabling the busbar to operate stably for extended periods under high current conditions. Because the cooling structure is integrated within the busbar, the external outline of the busbar system is simplified, the footprint is reduced, and the space utilization within the fusion device is improved.

[0021] This invention places positive and negative busbars, each coated with a unipolar insulating layer, side-by-side and tightly fitted together, and then completely covers both with an external insulating layer. After curing, the external insulating layer forms a closed circumferential constraint to resist the electromagnetic repulsion force generated when the positive and negative busbars are energized. The external insulating layer and the unipolar insulating layer are tightly bonded without gaps, and the electromagnetic repulsion force is evenly transmitted to the external insulating layer through the insulating layer itself. The high-strength fiber structure of the external insulating layer bears the circumferential tensile stress. This design eliminates the need for additional metal reinforcement blocks and special clamps to prevent loosening at the busbar connections and deformation of the main structure. It reduces the number of parts, avoids the risk of eddy current heating introduced by metal clamps, and improves the electrical safety and mechanical reliability of the system.

[0022] The external insulation layer of this invention is made of fiber-reinforced resin-based composite material and manufactured using a continuous fiber circumferential winding process. The insulation layer possesses electrical insulation properties, high-temperature resistance, and circumferential mechanical strength. The winding process ensures that the reinforcing fibers are oriented circumferentially, fully utilizing their tensile strength and providing mechanical protection against electromagnetic repulsion. This composite material also exhibits halogen-free flame-retardant properties, further enhancing the overall safety level of the device. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0025] Figure 2 This is a perspective view of the present utility model.

[0026] Figure 3 This utility model Figure 2 Top view.

[0027] Figure label: 101 Positive busbar, 102 Negative busbar, 103 Positive busbar insulation layer, 104 Negative busbar insulation layer, 105 External insulation layer, 106 Positive busbar internal cooling water channel, 107 Negative busbar internal cooling water channel. Detailed Implementation

[0028] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0029] In the description of the embodiments of this utility model, it should be understood that the terms "length", "vertical", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this utility model.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0031] In this embodiment of the invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this embodiment of the invention according to the specific circumstances.

[0032] In this embodiment of the invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0033] The following disclosure provides many different implementations or examples for different structures of the embodiments of the present invention. To simplify the disclosure of the embodiments of the present invention, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the embodiments of the present invention. Furthermore, reference numerals and / or reference letters may be repeated in different examples of the embodiments of the present invention; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various implementations and / or arrangements discussed.

[0034] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0035] Example 1: See Figures 1-3 This embodiment provides a copper-aluminum DC transmission busbar structure, with a cross-section as shown in the figure. Figure 1 As shown. The copper-aluminum DC transmission busbar structure includes a positive busbar 101, a negative busbar 102, a positive busbar insulation layer 103, a negative busbar insulation layer 104, and an external insulation layer 105.

[0036] The positive busbar 101 is made of 6063-T6 aluminum alloy.

[0037] The resistivity of 6063-T6 aluminum alloy at 20℃ is approximately 3.2 × 10⁻⁻⁻⁶. 8 The conductivity is Ω·m, corresponding to approximately 53% IACS (International Standard for Annealed Copper). The positive electrode busbar 101 is integrally formed by hot extrusion at a temperature of 430℃ to 480℃ and an extrusion ratio of 20:1 to 40:1. The positive electrode busbar 101 has a length of 6000mm, a cross-sectional width of 300mm, and a thickness of 100mm. An internal cooling water channel 106, with a diameter of 20mm, is formed running through the length of the positive electrode busbar 101. The axis of the internal cooling water channel 106 is located at the geometric center of the cross-section of the positive electrode busbar 101. The surface roughness Ra of the inner wall of the channel is no greater than 3.2μm.

[0038] The negative busbar 102 is also made of 6063-T6 aluminum alloy and is integrally formed through a hot extrusion process. The negative busbar 102 is 6000mm long, 300mm wide, and 100mm thick. An internal cooling water channel 107, with a diameter of 20mm, is formed running through the interior of the negative busbar 102 along its length. The axis of the internal cooling water channel 107 is located at the geometric center of the cross-section of the negative busbar 102.

[0039] The positive busbar insulation layer 103 is formed by winding epoxy resin-based glass fiber prepreg. The areal density of the prepreg is 200 g / m², the resin content is 35% ± 3%, and the thickness of a single layer after curing is approximately 0.25 mm. During winding, the prepreg is wound circumferentially around the outer surface of the positive busbar 101 with a 50% overlap rate, for a total of 12 layers, with a total thickness of 3 mm.

[0040] After winding, the material is placed in an oven for curing. The curing process is as follows: heat from room temperature to 80°C and hold for 2 hours; continue heating to 130°C and hold for 2 hours; continue heating to 160°C and hold for 4 hours; then cool to room temperature in the oven. After curing, the positive busbar insulation layer 103 and the positive busbar 101 form a tight, gapless bond, and the dielectric strength of the positive busbar insulation layer 103 is not less than 20kV / mm.

[0041] The negative busbar insulation layer 104 uses the same materials and processes as the positive busbar insulation layer 103. Prepreg is wound onto the outer surface of the negative busbar 102 in the same manner, with 12 layers for a total thickness of 3 mm, and cured under the same conditions. After curing, the negative busbar insulation layer 104 and the negative busbar 102 form a tight, gapless bond.

[0042] The positive busbar 101, covered with the positive busbar insulation layer 103, and the negative busbar 102, covered with the negative busbar insulation layer 104, are placed side-by-side with their wide sides facing each other. The cross-sectional outline of the assembled unit is approximately rectangular, with a width of about 312 mm and a thickness of about 106 mm (including the thickness of the single-pole insulation layers on both sides). When energized, the positive busbar 101 and the negative busbar 102 carry currents in opposite directions.

[0043] The outer insulation layer 105 uses the same epoxy resin-based glass fiber composite material as the unipolar insulation layer, and is integrally wrapped with the positive electrode busbar 101 and negative electrode busbar 102 placed side by side through a continuous fiber circumferential winding process. The glass fiber used for winding is E-glass alkali-free glass fiber roving with a linear density of 2400 tex. Before winding, the fibers are impregnated with epoxy resin solution with a viscosity of 800 mPa·s to 1200 mPa·s. During the winding process, a constant tension of 60 N is applied to the fiber bundle to eliminate interlayer air bubbles and improve interlayer density.

[0044] The fiber volume content of the winding layer is controlled at 65% ± 3%. The total thickness of the outer insulation layer 105 is 8 mm, with a total of 32 layers. After winding, it is placed in an oven for curing according to the same stepped temperature rise curve as the single-pole insulation layer. After curing, the outer insulation layer 105 forms a closed circumferential constraint structure on the outside of the positive busbar 101 and negative busbar 102 assembly. The outer insulation layer 105 is tightly bonded to the positive busbar insulation layer 103 and to the negative busbar insulation layer 104 without gaps.

[0045] The circumferential tensile strength of the outer insulation layer 105 is tested to be no less than 280 MPa, and the circumferential elastic modulus is no less than 30 GPa.

[0046] Example 2: Based on Example 1, this example optimizes the arrangement of the cooling water flow channels 106 and 107 in the positive busbar to meet the uniform heat dissipation requirements of a larger cross-section.

[0047] In this embodiment, the positive busbar 101 has a cross-sectional width of 450 mm, a thickness of 120 mm, and a length of 6000 mm. Three internal cooling water channels 106 are uniformly formed along the width direction inside the positive busbar 101, each with a diameter of 16 mm. The axial spacing between adjacent internal cooling water channels 106 is 120 mm, and the distance from the outermost channel axis to the edge of the busbar is 105 mm. The axes of the three internal cooling water channels 106 are located in the same horizontal plane, which is located at the geometric center of the thickness direction of the positive busbar 101.

[0048] The negative busbar 102 has a cross-sectional width of 450 mm, a thickness of 120 mm, and a length of 6000 mm. Three internal cooling water channels 107 are evenly distributed along the width direction inside the negative busbar 102. The diameter of each internal cooling water channel 107 is 16 mm, and the axial spacing between adjacent channels is 120 mm.

[0049] The materials and processes of the positive busbar insulation layer 103 and the negative busbar insulation layer 104 are the same as in Example 1, and the winding thickness is still 3mm.

[0050] The three internal cooling water channels 106 of the positive busbar 101 are connected in parallel to the cooling water, and each channel inlet is equipped with a flow regulating valve to ensure uniform flow distribution. Similarly, the three internal cooling water channels 107 of the negative busbar 102 are connected in parallel to the cooling water. The cooling water flow velocity remains 2.5 m / s.

[0051] By increasing the number of flow channels and rationally arranging the channel spacing, the temperature distribution within the cross-section of the positive busbar 101 becomes more uniform. Finite element thermal analysis verifies that, under a 70kA current condition, the difference between the highest and lowest temperatures within the cross-section of the positive busbar 101 is controlled within 8℃, while the maximum temperature difference in the single-channel scheme (corresponding to the cross-sectional dimensions of Example 1) is approximately 15℃. The highest conductor temperature is reduced by about 5℃ compared to the single-channel scheme.

[0052] The winding thickness of the outer insulation layer 105 was adjusted to 10 mm, with a total of 40 layers wound to provide circumferential constraint stiffness matching the larger cross-sectional size. The winding process parameters were the same as in Example 1.

[0053] The remaining structures, materials, and processes of this embodiment are the same as those of Embodiment 1.

[0054] Example 3: This example is basically the same as Example 1, except that the outer insulation layer 105 is formed by using a prefabricated split tube shell structure instead of the continuous fiber circumferential winding molding process.

[0055] In this embodiment, the outer insulation layer 105 is a pre-formed epoxy resin-based glass fiber composite split-shell structure. The split-shell structure consists of two halves: an upper shell and a lower shell. Each half is formed by a molding process at a molding temperature of 150°C, a pressure of 5 MPa, and a holding time of 30 minutes. The wall thickness of each half is 10 mm, and the shape of its inner cavity precisely matches the outer contour of the positive busbar 101 and negative busbar 102 assembly placed side by side. The inner surfaces of the upper and lower shells are provided with positioning grooves extending along the length direction to accommodate the outer surface protrusions of the positive busbar insulation layer 103 and the negative busbar insulation layer 104.

[0056] During assembly, the upper and lower housings are respectively fastened to the top and bottom of the positive busbar 101 and negative busbar 102 assembly, ensuring the positioning grooves are flush with the outer surface of the single-pole insulation layer. After fastening, a stainless steel fastening band is installed every 500mm along the length direction for secure clamping. The fastening band is 30mm wide and 2mm thick, and the pre-tightening force is adjusted by bolts, with a pre-tightening torque of 20N·m. A 1mm thick epoxy fiberglass cloth insulating pad is placed between the fastening band and the outer insulation layer 105 to prevent direct contact and wear between the fastening band and the outer insulation layer 105 and to enhance electrical insulation.

[0057] The remaining structure of this embodiment is the same as that of Embodiment 1. This split-shell design is suitable for on-site installation conditions where space is limited and winding operations are inconvenient, while also facilitating segmented disassembly and maintenance.

[0058] Example 4: This example is basically the same as Example 1, except that the positive busbar 101 and the negative busbar 102 are made of T2 copper.

[0059] The resistivity of T2 copper at 20℃ is approximately 1.72 × 10⁻⁻⁻⁶. 8 The conductivity is approximately 100% IACS (100 Ω·m). Compared to 6063-T6 aluminum alloy, T2 copper has a conductivity approximately 88% higher. Under the same 70kA current condition and the same cross-sectional dimensions, the Joule heat power per unit length of the T2 copper busbar is approximately 53% of that of the aluminum alloy busbar. Therefore, the diameters of the cooling water flow channels 106 and 107 in the positive and negative busbars can be reduced accordingly.

[0060] In this embodiment, the positive busbar 101 has a cross-sectional width of 180 mm and a thickness of 60 mm. The diameter of the cooling water flow channel 106 inside the positive busbar is reduced to 12 mm. The negative busbar 102 has a cross-sectional width of 180 mm and a thickness of 60 mm. The diameter of the cooling water flow channel 107 inside the negative busbar is reduced to 12 mm.

[0061] The winding thickness of the positive busbar insulation layer 103 and the negative busbar insulation layer 104 remains 3mm. The winding thickness of the outer insulation layer 105 is adjusted to 5mm, with a total of 20 layers.

[0062] Based on thermal balance calculations, under the same cooling water flow rate (2.5 m / s) and inlet water temperature (30℃), the maximum conductor temperature can be controlled below 82℃. Because copper has a higher density (approximately 8.96 g / cm³) than aluminum (approximately 2.70 g / cm³), the total weight of copper busbars is slightly higher than that of aluminum busbars. However, copper busbars offer superior electrical conductivity and heat dissipation, making them suitable for applications where conductor cross-sectional dimensions are strictly limited and weight is not a major concern.

[0063] The rest of the structure in this embodiment is the same as in embodiment 1.

[0064] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0065] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. It should be noted that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A copper-aluminum DC transmission busbar structure, characterized in that: It includes the positive busbar, the negative busbar, the positive busbar insulation layer, the negative busbar insulation layer, and the external insulation layer; The positive busbar has a cooling water channel running through it along its length, and the negative busbar has a cooling water channel running through it along its length. The positive busbar insulation layer tightly covers the outer surface of the positive busbar, and the negative busbar insulation layer tightly covers the outer surface of the negative busbar; The positive busbar covered with the insulation layer of the positive busbar and the negative busbar covered with the insulation layer of the negative busbar are placed side by side and close together; The external insulation layer completely covers and fixes the positive busbar and negative busbar placed side by side, and the external insulation layer is tightly bonded to the positive busbar insulation layer and the negative busbar insulation layer without gaps. The external insulation layer is a pre-formed epoxy resin-based glass fiber composite split-shell structure, which consists of an upper shell and a lower shell.

2. The copper-aluminum DC transmission busbar structure of claim 1, wherein: The positive busbar and the negative busbar are made of aluminum or copper.

3. The copper-aluminum DC transmission busbar structure according to claim 2, characterized in that: The positive and negative busbars are made of 6063-T6 aluminum alloy.

4. The copper-aluminum DC transmission busbar structure according to claim 2, characterized in that: The positive and negative busbars are made of T2 copper.

5. The copper-aluminum DC transmission busbar structure according to claim 1, characterized in that: The positive busbar has a cross-sectional width of 120mm to 600mm and a thickness of 60mm to 300mm; the negative busbar has a cross-sectional width of 120mm to 600mm and a thickness of 60mm to 300mm.

6. The copper-aluminum DC transmission busbar structure according to claim 1, characterized in that: The diameters of the cooling water channels in the positive and negative busbars are predetermined based on the current load and heat dissipation conditions. The axis of the cooling water channel in the positive busbar is located at the geometric center of the cross-section of the positive busbar, and the axis of the cooling water channel in the negative busbar is located at the geometric center of the cross-section of the negative busbar.

7. The copper-aluminum DC transmission busbar structure according to claim 6, characterized in that: Multiple cooling water channels are uniformly opened inside the positive busbar along the width direction, and multiple cooling water channels are uniformly opened inside the negative busbar along the width direction.

8. The copper-aluminum DC transmission busbar structure according to claim 1, characterized in that: The positive busbar insulation layer, the negative busbar insulation layer, and the external insulation layer are all made of fiber-reinforced resin-based composite material.

9. A copper-aluminum DC transmission busbar structure according to claim 8, characterized in that: The fiber-reinforced resin-based composite material is an epoxy resin-based glass fiber composite material.

10. A copper-aluminum DC transmission busbar structure according to claim 1, characterized in that: The outer insulation layer is manufactured using a continuous fiber circumferential winding molding process, and the fiber volume content of the winding layer is not less than 60%.

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