Coaxial twin-core high-voltage cable and method for manufacturing the same

Abstract

The present disclosure relates to a coaxial twin-core high voltage (HV) cable including a first elongated hollow extrusion of conductive metal forming a first conductor and a second elongated hollow extrusion of conductive metal forming a second conductor, the second conductor being coaxially disposed inside the first conductor. A first electrical insulation layer is disposed between the first and second conductors and coats the outer surface of the second conductor and the inner surface of the first conductor, and a second electrical insulation layer coats the outer surface of the first conductor. The present disclosure also relates to a method of manufacturing such a cable and uses of such a cable.

Description

[Technical Field]

[0001] The present application relates to internally and / or externally cooled coaxial twin-core high-voltage cables and methods of manufacturing the same. The present application also relates to externally and / or internally cooled flat-formed coaxial twin-core high-voltage cables and methods of manufacturing the flat-formed cables. The coaxial twin-core high-voltage cables of the present disclosure are particularly suitable for use in vehicles such as electric vehicles and hybrid electric vehicles. [Background technology]

[0002] High-voltage (HV) cables for transmitting power at high voltages are used in a variety of applications, such as ignition systems and alternating current (AC) or direct current (DC) power transmission. HV cables are also used in the field of hybrid electric vehicle (HEV) or electric vehicle (EV) technology, where voltage power from a battery is amplified by an inverter and output to a drive motor via a large-diameter high-voltage power cable with sufficient current capacity.

[0003] As demand for and technological developments in hybrid electric vehicles and electric vehicle technology continue, the size of HV cables used as power cables is increasing due to the increased voltages used in power transmission. At high voltages, conductive materials tend to become very hot unless the cable has a sufficiently large diameter. There is also an ongoing effort to reduce the size of the engine compartment and the weight of all components within the vehicle. Therefore, there is a need for HV cables that allow for a reduction in the size and weight of components within the vehicle. Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE INVENTION An object of the present invention is to provide a high voltage cable that is lightweight and space-saving. [Means for solving the problem]

[0005] This object is achieved by the subject matter of the attached independent claims.

[0006] According to a first aspect, the present disclosure relates to a coaxial twin-core high-voltage (HV) cable including a first elongated extruded hollow section of a conductive metal forming a first conductor, a second elongated extruded section of a conductive metal forming a second conductor, the second conductor being coaxially disposed inside the first conductor, and a first electrical insulation layer disposed between the first conductor and the second conductor and coating an outer surface of the second conductor and an inner surface of the first conductor, the second electrical insulation layer coating the outer surface of the first conductor.

[0007] The second conductor can be either a solid rod or a hollow section having at least one void along its length.

[0008] The coaxial twin core HV cable may have a cross-sectional shape selected from circular, round, elliptical, flattened elliptical (stadium), rectangular, oval, square or polygonal.

[0009] The coaxial twin-core HV cable may have a flat cross-sectional shape, and a first electrical insulation layer disposed between the first conductor and the second conductor is in direct contact with an outer surface of the second conductor and an inner surface of the first conductor, and the first electrical insulation layer has a substantially uniform thickness.

[0010] The coaxial twin-core HV cable may further include at least one cooling channel for the flow of a cooling medium, the at least one cooling channel being an extruded metal tube coaxially arranged inside the at least one void of the second conductor, and a third electrical insulation layer being arranged between an outer surface of the at least one cooling tube and an inner surface of the at least one void of the second conductor.

[0011] The coaxial twin-core HV cable may include two cooling channels, a first cooling channel for the flow of a cooling medium and a second cooling channel for the return flow of the cooling medium.

[0012] The two cooling channels may be formed by a single extruded cooling tube having two axially extending parallel channels.

[0013] The two cooling channels may be formed by two separate extruded axially extending tubes.

[0014] The first conductor, the second conductor and the at least one cooling tube are made of a metal selected from aluminum, an aluminum alloy, copper or a copper alloy, preferably, the first conductor, the second conductor and the at least one cooling tube are made of aluminum or an aluminum alloy.

[0015] In a preferred embodiment, the first conductor and / or the second conductor are made of an alloy of the AA6XXX series or an alloy of the AA1XXX series.

[0016] The material of the first electrical insulating layer, and / or the second electrical insulating layer, and / or the third electrical insulating layer may have a dielectric strength of 30 to 70 kV / mm.

[0017] The material of the second electrical insulating layer may have a dielectric strength of 15 to 30 kV / mm.

[0018] According to a second aspect, the present disclosure relates to a method for manufacturing the above-mentioned coaxial twin-core high voltage cable, the method comprising the steps of: (i) providing a first extruded hollow section of a conductive metal and a second extruded section of a conductive metal, the second extruded section having a diameter smaller than the inner diameter of the hollow section of the first extruded hollow section, and the second extruded section being either a solid rod or a hollow section having at least one void extending along its length; (ii) applying a coating layer of a first electrically insulating material to an outer surface of the second extrusion profile to obtain a coated second extrusion profile having a first electrically insulating layer; (iii) placing the coated second extruded profile inside the first extruded hollow profile; and (a) expanding the coated second extruded tube until the first electrically insulating layer directly contacts and covers the inner surface of the first extruded hollow profile; or (b) reducing the diameter of the cross section of the first extruded hollow profile until the first electrically insulating layer directly contacts and covers the inner surface of the first extruded hollow profile; or (c) A combination of both (a) and (b) a step of assembling the first extruded hollow shape member and the second extruded shape member by the above method; (iv) applying a coating layer of a second electrically insulating material to the outer surface of the first extruded hollow profile; Includes.

[0019] The method may include applying a second electrically insulating layer before or after step (iii).

[0020] This method is - providing at least one cooling tube which is an extruded metal tube; - applying a coating layer of a third electrically insulating material to an outer surface of the at least one cooling tube to obtain at least one coated cooling tube; - disposing at least one coated cooling pipe inside a second extruded hollow profile having at least one void; and - expanding the at least one coated cooling tube until the third electrically insulating layer on the outer surface of the at least one cooling tube directly contacts and covers the inner surface of the cavity of the second extruded hollow profile; or - reducing the diameter of the cross section of the second extruded hollow profile until the third electrically insulating layer on the outer surface of the at least one cooling pipe directly contacts and covers the inner surface of the cavity of the second extruded hollow profile. performing one or both of the steps It may further include:

[0021] The method may further include flattening the cable.

[0022] The first extruded hollow profile, the second extruded profile and the at least one cooling pipe are made of a metal selected from aluminum, an aluminum alloy, copper or a copper alloy, preferably aluminum or an aluminum alloy.

[0023] According to a third aspect, the present disclosure relates to the use of the above-mentioned coaxial twin-core high voltage (HV) cable for transmitting power at high voltage in a hybrid electric vehicle (HEV), or in an electric vehicle (EV), or as a charging cable in a charging unit or charging station, or in a charging station infrastructure, or in an electric ship or hybrid electric ship, or in a data center, or in a wind turbine or wind turbine park, or in a PV system. [Brief explanation of the drawings]

[0024] [Figure 1a] 1 shows a perspective view of a portion of a coaxial twin-core HV cable according to the present disclosure, with the various layers of the cable shown for illustrative purposes. [Figure 1b] 1a shows a side view of a portion of the coaxial twin-core HV cable of FIG. 1a. [Figure 1c] 1a and 1b show cross-sectional views of the coaxial twin-core HV cable. [Figure 2] 1 shows a perspective view of a portion of a flat-formed coaxial twin-core HV cable according to the present disclosure. [Figure 3] 1 shows a cross-sectional view of a portion of a flat coaxial twin-core HV cable according to the present disclosure. [Figure 4a] 1 shows a perspective view of a portion of one exemplary embodiment of a coaxial twin-core HV cable according to the present disclosure having internal cooling channels. [Figure 4b] 1 shows a perspective view of a portion of one exemplary embodiment of a coaxial twin-core HV cable according to the present disclosure having internal cooling channels. [Figure 4c] 1 shows a perspective view of a portion of one exemplary embodiment of a coaxial twin-core HV cable according to the present disclosure having internal cooling channels. [Figure 5]1 shows a cross-sectional view of a flat-formed coaxial twin-core HV cable according to the present disclosure with internal cooling channels. DETAILED DESCRIPTION OF THE INVENTION

[0025] In the following description, various examples and embodiments of the present invention are described to provide those skilled in the art with a more detailed understanding of the present invention. The specific details set forth in connection with the various embodiments and with reference to the accompanying drawings are not intended to be construed as limiting. Rather, the scope of the present invention is defined by the appended claims.

[0026] Throughout this specification and claims, unless the context clearly dictates otherwise, the following terms have the meanings expressly set forth herein. As used herein, the phrase "in one embodiment" may refer to the same embodiment, but does not necessarily refer to the same embodiment. Furthermore, as used herein, the phrase "in another embodiment" may refer to different embodiments, but does not necessarily refer to different embodiments. Thus, as discussed below, various embodiments of the invention can be readily combined without departing from the scope of the invention.

[0027] Additionally, as used herein, the term "or" is an inclusive "or" operator and is equivalent to the term "and / or" unless the context clearly dictates otherwise. The term "based on" is not exclusive and allows for additional, unlisted elements to be based on, unless the context clearly dictates otherwise. Additionally, throughout this specification, the meanings of "a," "an," and "the" can include plurals. The meaning of "in" includes "in" and also includes plural references. The meaning of "in" includes "in" and "on."

[0028] The present disclosure aims to provide a lightweight, space-saving coaxial twin-core high-voltage cable (hereinafter also referred to as "cable"). The described cable is suitable for applications where the voltage is 600-1200V, for example, in electric vehicles, but can also be used in other voltage ranges, for example, up to 2500V or higher. The cable has excellent internal and / or external cooling capabilities, thus avoiding heat buildup within the cable core. The cable is particularly suitable for installation in electric vehicles or hybrid electric vehicles. The cable is also suitable for connection to charging cables in charging units or charging stations or for use in charging station infrastructure. Other suitable applications of the cable are marine vessels, electric or hybrid electric vessels such as ships and boats, data centers, wind turbines, PV systems, and any other installation requiring HV transmission cables.

[0029] Accordingly, the present disclosure relates to a coaxial twin-core high-voltage (HV) cable including a first elongated hollow extruded section of conductive metal forming a first conductor (also referred to as the "outer conductor"), a second elongated hollow extruded section of conductive metal forming a second conductor (also referred to as the "inner conductor"), the second conductor being coaxially disposed inside the first conductor, a first electrical insulating layer securely disposed between the first and second conductors and coating the outer surface of the second conductor and the inner surface of the first conductor, and a second electrical insulating layer / sheath coating the outer surface of the first conductor. By providing the first electrical insulating layer securely secured between the inner and outer conductors and in direct contact with the entire surface areas of the adjacent inner and outer conductors, a large contact surface area and excellent heat transfer are achieved between the inner and outer conductors. Additionally, the first electrical insulation layer, located between the inner and outer conductors, securely holds the cable in place, allowing it to bend without compromising its heat transfer capabilities or insulating properties. Furthermore, due to the concentric conductors, coaxial twin-core HV cables do not require shielding or filtering to minimize electromagnetic interference. The improved cooling and elimination of the shielding layer allow for smaller cable cross-sections for higher voltage applications and capacities.

[0030] As used herein, with respect to the first electrical insulating layer disposed between the inner (second) conductor and the outer (first) conductor, expressions such as "direct contact" or "directly contacting" should be understood to mean that the first electrical insulating layer contacts and covers, preferably without gaps, the entire inner surface of the first (outer) conductor and the outer surface of the second (inner) conductor, including after bending operations. The same should be understood to apply to the disclosure regarding the third electrical insulating layer disposed between at least one cooling tube and the inner conductor.

[0031] The conductive metal forming the outer (first) conductor and the inner (second) conductor may be selected from aluminum, an aluminum alloy, copper, or a copper alloy. The conductive metal is preferably aluminum or an aluminum alloy, since aluminum significantly reduces the weight of the cable compared to copper. Furthermore, aluminum may also be a more sustainable material choice due to its lower cost compared to copper. Particularly suitable aluminum alloys for the inner and outer conductors are the AA6XXX and AA1XXX series aluminum alloys. In this disclosure, references to the AA1XXX and AA6XXX series aluminum alloys are based on the American Aluminum Association nomenclature, which uses a four-digit system for wrought alloy composition families (see "International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys" by The Aluminum Association, Inc.).

[0032] Coaxial twin-core HV cables may have a substantially circular, round, elliptical, flattened elliptical (stadium or pill), rectangular, oval, square, or polygonal cross-sectional shape. The generally flat shape of the cable is advantageous because the larger surface area of ​​a flat cable provides better heat dissipation (external cooling, "passive" cooling) compared to a round or non-flat cable. Therefore, a flat cable allows for a reduction in both the volume and the total weight of the cable. The generally flat shape is also advantageous with regard to the placement and stacking of cables, since less space is required.

[0033] The first electrical insulation layer is made of a non-conductive material that can adequately withstand bending, has adequate dielectric strength, and prevents the passage of electrical current between the inner conductor and the outer conductor. The material for the first electrical insulation layer preferably has a dielectric strength of 30 to 70 kV / mm, more preferably at least 40 kV / mm. This allows the first electrical insulation layer to be relatively thin, providing sufficient electrical insulation while allowing efficient heat transfer from the inner conductor. The material for the first electrical insulation layer can be a polymer material such as polyethylene or polyamide, e.g., PA12, that has sufficient dielectric strength and can therefore be thin enough to achieve efficient heat transfer from the inner conductor to the outer conductor. Other advantageous properties of the first electrical insulation layer material include good adhesion properties, flame retardancy, and good thermal conductivity.

[0034] It is important to avoid short circuits and injury to equipment and personnel. Therefore, the first electrical insulation layer should preferably tightly cover and contact the entire outer surface of the inner conductor and preferably also contact the entire inner surface of the outer conductor. It should be understood that a portion of the end of the inner conductor may not be covered by the electrical insulation layer to allow electrical connection to the connection point. Advantageously, as described in more detail below, the first electrical insulation layer is first applied to the inner conductor, which is then inserted into the outer conductor, after which the inner conductor is expanded or, alternatively, the cross-sectional diameter of the outer conductor is reduced. The material of the electrical insulation layer may be applied to obtain a permanent bond between the inner conductor and the insulation layer, such as chemical bonding, for example, by applying a primer or adhesive to the surface of the inner conductor before applying the insulation layer, or by any other suitable pretreatment.

[0035] High-voltage cables must be outwardly insulated to prevent the conductor from coming into contact with other objects or people. Therefore, the cable includes a second electrical insulation layer disposed on the outer surface of the outer conductor to prevent undesired short circuits and other damage. The material of the second electrical insulation layer is suitably a non-conductive polymer material and may have a lower dielectric strength than the material of the first electrical insulation layer, such as 15 to 30 kV / mm or 20 to 25 kV / mm. The material of the second electrical insulation layer may have a higher dielectric strength; for example, the material of the second electrical insulation layer may be the same as the first insulation layer. On the outside of the conductor, the requirements for good heat transfer may be less severe, and therefore the second electrical insulation layer may have a greater material thickness than the first electrical insulation layer. For example, the second electrical insulation layer may be made of a polymer material, such as polyethylene (XLPE), which is significantly less expensive than materials with higher dielectric strength. The second electrical insulation layer is preferably not permanently adhered to the surface of the conductor so that it can be peeled off for electrical connection purposes.

[0036] The ends of the inner and outer conductors may be shaped to form separate connections, which in a preferred embodiment are integral with the conductors of the cable.

[0037] According to a first embodiment, the coaxial twin-core HV cable according to the present disclosure has a flat cross-sectional shape. The flat shape of the cable cross-section is advantageous because it allows for better heat dissipation due to a large surface area relative to the cross-sectional area of ​​the conductor. A flat cable may have a cross-sectional shape having a substantially oval, elliptical or flattened elliptical (stadium-shaped) shape. The term "flat" should be understood to include cable cross-sectional shapes in which the ratio of the transverse direction (width w) to the height h exceeds 1. The w / h ratio should preferably be at least 1.5 or at least 2, for example, 2 to 8 or 4 to 7. The outer conductor (first conductor) is composed of an elongated extruded hollow section (first extrusion section). The inner conductor may be composed of a solid or extruded hollow section (second extrusion section). The cross-sectional shapes of the first and second extrusions are preferably adapted so that the second extrusion fits within the longitudinal hollow of the first extrusion, and the first electrical insulating layer disposed between the two extrusions is secured in place, completely covering the outer surface of the inner conductor and the inner surface of the outer conductor. Furthermore, the first electrical insulating layer has a substantially uniform thickness throughout the entire length of the straight cable. A flat cable shape can be obtained by flattening the assembly of the inner conductor and the outer conductor with the insulating layer disposed therebetween. Flattening can be achieved by rolling, pressing, drawing, or any other suitable method. In one embodiment, the inner conductor is made from an extruded hollow profile having a cross-sectional shape corresponding to the outer conductor. This embodiment can facilitate the manufacturing and flattening process of the conductor assembly. The flattening process can cause the inner conductor to assume a strip-like shape when the hollow profile is compressed. The flat cable includes an insulating layer / sheath on the outer surface of the outer conductor. The outer insulating layer / sheath can be applied before or after flattening the conductor assembly.

[0038] It should be understood that a coaxial twin-core HV cable may have a flattened shape along one or more portions of its longitudinal length, and thus the cross-sectional shape of the cable may vary along its longitudinal length. Different cross-sectional shapes along the length of the cable may be advantageous to facilitate placement and installation of the cable.

[0039] The conductive metals, first electrically insulating material and second insulating material for the outer conductor and inner conductor according to the first embodiment correspond to the same as described above.

[0040] In a second embodiment, a coaxial twin-core HV cable according to the present disclosure may include at least one internal cooling channel for passing a cooling medium through the interior of the cable, thereby cooling the cable. In this second embodiment, the inner (second) conductor is constructed from an elongated extruded hollow section having at least one hollow void throughout its length. The outer (first) conductor is constructed from a hollow elongated extruded section, as described above. A first electrical insulation layer is disposed between the inner and outer conductors and completely covers the outer surface of the inner conductor and the inner surface of the outer conductor, corresponding to what has been described above. The first insulation layer has a substantially uniform thickness and is securely held in place by the inner and outer conductors. At least one cooling channel is disposed within the at least one void in the inner (second) conductor and extends longitudinally along the cable. An electrical insulation layer, referred to herein as a third electrical insulation layer, is disposed between the outer surface of the at least one cooling channel and the inner surface of the void in the hollow inner conductor.

[0041] At least one cooling channel (also referred to herein as a cooling tube) is preferably made from an extruded metal tube, since metals have good heat transfer properties and are impermeable to gases and liquids. The cooling tube may advantageously be made from aluminum, an aluminum alloy, copper, or a copper alloy. Since aluminum and aluminum alloys are lighter and relatively less expensive than copper, the at least one cooling tube is preferably made from aluminum or an aluminum alloy. A suitable aluminum alloy for the cooling tube may be, for example, an alloy of the AA3XXX series, such as AA3003. The alloy used for the cooling tube should preferably have good drawability. The alloy should also preferably have acceptable corrosion resistance.

[0042] The at least one cooling channel may be two channels extending parallel to the longitudinal direction or an extruded aluminum tube with at least two channels, through which a cooling medium can flow in the same or opposite directions. Alternatively, the at least two cooling channels may consist of two or more cooling pipes disposed within the inner conductor and through which a cooling medium can flow in the same or opposite directions. In the example of two separate cooling pipes, the inner conductor may have two longitudinal hollows extending throughout the length of the section to accommodate the cooling pipes. A single cooling pipe with two channels or two separate cooling pipes allows the introduction and discharge of cooling fluid from the same end of the cable, thereby enabling the use of a single connection for supplying and collecting the cooling fluid / medium. In such an embodiment, the opposite ends of the cooling channels may be closed by a capping device to direct the flow of cooling medium from the inlet channel to the return channel. The at least one cooling channel may have a length greater than the inner and outer conductors. Furthermore, the at least one cooling channel may be equipped or configured with a means for enabling rapid connection of the cooling medium / fluid to the cooling pipe. The outer surface of the at least one cooling channel extending from the cable is preferably completely covered / insulated by a third electrically insulating layer or other suitable insulating cover.

[0043] The third electrical insulation layer is made of a non-conductive material that can adequately withstand bending, has adequate dielectric strength, and prevents the passage of current between the at least one cooling channel and the inner conductor. The material for the third electrical insulation layer may have a dielectric strength of 30 to 70 kV / mm, preferably at least 40 kV / mm. This allows the third electrical insulation layer to be relatively thin, allowing efficient cooling of the inner and outer conductors while providing sufficient electrical insulation. The material for the third electrical insulation layer may be a polymer material such as polyethylene or polyamide, e.g., PA12, that has sufficient dielectric strength and is therefore thin enough to achieve efficient cooling of the coaxial twin-core HV cable. The third electrical insulation layer should preferably cover and contact the entire outer surface of the at least one cooling channel without any gaps, and preferably also contact the entire inner surface of the inner conductor. Other advantageous properties of the third electrical insulation layer material include good adhesion properties, flame retardancy, and good thermal conductivity.

[0044] Advantageously, as will be explained in more detail below, the third electrical insulating layer is first applied to the at least one cooling tube, which is then inserted into the inner conductor, after which the at least one cooling tube is expanded or, alternatively, the inner conductor is reduced in cross section. The material of the third electrical insulating layer may be applied in such a way that a permanent bond between the cooling tube and the insulating layer is obtained, such as chemical bonding, for example by applying a primer or adhesive to the surface of the cooling tube before applying the insulating layer, or by any other suitable pre-treatment.

[0045] The high voltage twin core cables of the present disclosure may have a smaller cross section than uncooled solid high voltage cables for corresponding voltage applications due to enhanced external and / or internal cooling. Thus, in any of the above-defined constructions or configurations, the cables may have a cross section of, for example, 70 to 500 mm 2 For example, the cross-sectional area may be 70 to 120 mm 2 Externally or internally cooled cables with a cross-sectional area of ​​about 200-250 mm for the same voltage applications. 2The cooling tube may suitably have an outer diameter of 6-10 mm. The small diameter and internal space allow for significant cost and weight savings. It should be understood that other cross-sectional areas and dimensions may be realized for different applications. In this context, the cable cross-sectional area refers to the cross-sectional area of ​​the conductor.

[0046] A typical operating environment temperature may be about 125°C.

[0047] Due to the preferred selection of metal extrusions for use as internal cooling tubes and conductors, the high voltage cables of the present disclosure may typically be inflexible and therefore may require the use of a bending tool to bend the cable into its final shape.

[0048] The present disclosure further relates to a method for manufacturing the above-mentioned coaxial twin-core high voltage cable, the method comprising the steps of: - providing a first extruded hollow section of conductive metal and a second extruded section of conductive metal, the second extruded section having a diameter smaller than the inner diameter of the hollow section of the first extruded hollow section, and the second extruded section (3) being either a solid rod or a hollow section having at least one void along its length; - applying a coating layer of a first electrically insulating material to an outer surface of the second extrusion profile to obtain a coated second extrusion profile having a first electrically insulating layer; - placing the coated second extruded profile inside the first extruded hollow profile; and (i) expanding the coated second extruded tube until the first electrically insulating layer directly contacts and covers the inner surface of the first extruded hollow profile; or (ii) reducing the diameter of the cross section of the first extruded hollow profile until the first electrically insulating layer directly contacts and covers the inner surface of the first extruded hollow profile; or (iii) a combination of both (i) and (ii) and - applying a coating layer of a second electrically insulating material to an outer surface of the first extruded hollow profile; Includes.

[0049] The reduction of the cross section of the hollow section may be achieved by cold working such as hammering, pressing, roll forming, drawing or other methods known to those skilled in the art.

[0050] The second extruded profile can be a solid profile or a hollow profile with at least one void along its entire length. The cross-sectional shape of the first extruded hollow profile, particularly the cross-sectional shape of the longitudinal void of the first extruded hollow profile, should preferably correspond to the outer cross-sectional shape of the second extruded profile. Having corresponding cross-sectional shapes of the first and second profiles facilitates assembly of the extruded profiles.

[0051] The first electrical insulation layer may be applied to the outer surface of the second extruded profile by any suitable method, such as coextrusion, powder coating, using adhesives, or other methods known to those skilled in the art. The material of the first electrical insulation layer may be applied to provide a permanent bond between the inner conductor and the insulation layer, such as chemical bonding, for example, by applying a primer or adhesive to the surface of the inner conductor before applying the insulation layer, or by any other suitable pretreatment. It should be understood that a portion of one or both ends of the inner conductor may not be coated for electrical connection.

[0052] The second electrical insulation layer can be applied to the outer surface of the first extruded profile by any suitable method that can correspond to the above-described methods for applying the first electrical insulation layer. Therefore, the method for applying the second electrical insulation layer can include coextrusion, powder coating, or other suitable methods. The application of the second insulation layer to the outer surface of the first extruded hollow profile can be performed before or after the first extruded hollow profile and the second extruded profile are assembled.

[0053] Assembling the first and second extrusion profiles involves placing the coated second extrusion profile within the longitudinal hollow of the first extrusion profile. At least one of these profiles is then deformed so that the first electrical insulation layer is in firm contact with the inner surface of the first extrusion profile (outer conductor) and the outer surface of the second extrusion profile (inner conductor). If the coated second extrusion profile is a hollow profile, deformation can be achieved by expanding the coated second extrusion profile until the first electrical insulation layer completely and securely contacts and covers the inner surface of the first extrusion profile. Profile expansion can be achieved by methods known to those skilled in the art, such as plug drawing and hydroforming. Alternatively, deformation can be achieved by reducing the cross-section of the first extrusion profile until the first electrical insulation layer completely and securely contacts and covers the inner surface of the first extrusion profile. The reduction in cross section can be achieved by any method known to those skilled in the art, preferably cold working, such as hammering, pressing, roll forming, drawing, etc. It is understood that deformation by both expansion and reduction in cross section is also possible.

[0054] In a first embodiment of the method, the method relates to the manufacture of a flattened coaxial-twin-core HV cable. The method for manufacturing a flattened cable may include using first and second extrusions having a generally oval, elliptical, or flattened elliptical (stadium-shaped) cross-sectional shape. The assembly of the extrusions may be performed as described above. Another method for manufacturing a flattened coaxial-twin-core HV cable may include assembling the extrusions as described above, followed by flattening the assembly. In this method, the second extrusion constituting the inner conductor is preferably a hollow extrusion such as a tube. After flattening, the inner hollow extrusion (inner conductor) is pressed flat into a strip-like shape, the outer conductor surrounds the inner conductor, and the first electrical insulating layer is held in place during the flattening process. The flattening may be achieved by rolling, pressing, drawing, or any other suitable method known to those skilled in the art. An insulating layer / sheath may be applied to the outer surface of the outer conductor before or after flattening the conductor assembly.

[0055] In a second embodiment of the method, the method comprises: (a) providing at least one cooling channel that is an extruded metal tube; (b) applying a coating layer of a third electrically insulating material to an outer surface of the at least one cooling channel to obtain at least one coated cooling channel; (c) disposing at least one coated cooling channel inside the longitudinal cavity of the second hollow extruded tube; and - extending the at least one coated cooling channel until the third electrically insulating layer on the outer surface of the at least one cooling channel directly contacts and covers the inner surface of the hollow space of the second extruded tube; or - reducing the diameter of the cross section of the second extruded hollow profile, or a combination of expanding and reducing the cross section, until the third electrically insulating layer on the outer surface of the at least one cooling channel directly contacts and covers the inner surface of the hollow space of the second extruded pipe. and Further includes:

[0056] The at least one cooling channel is preferably an extruded tube of aluminum or aluminum alloy.

[0057] Advantageously, the at least one coated cooling channel is assembled with the inner conductor by expanding the cooling channel, which can be performed, for example, by plug drawing or hydroforming.

[0058] Furthermore, a second embodiment of this method includes the steps of positioning an assembly of an inner conductor having at least one cooling channel within a longitudinal hollow portion of a first extrusion profile (outer conductor), and reducing the cross section of the outer conductor until the inner surface of the hollow cavity contacts and is completely covered by the first electrical insulation layer on the outer surface of the inner conductor.

[0059] Exemplary Embodiments The present disclosure will be described below with reference to the accompanying drawings, which illustrate preferred exemplary embodiments of the present disclosure. However, the present disclosure may be embodied in other forms and should not be construed as limited to the embodiments disclosed herein. The disclosed embodiments are provided to fully convey the scope of the present disclosure to those skilled in the art. It should be understood that the dimensions and size ratios in the drawings are for illustrative purposes only and should not be construed as limiting.

[0060] In the drawings, like reference numerals represent like parts throughout the various views unless otherwise specified.

[0061] 1a-c show a coaxial-twin HV cable 1 including a hollow outer conductor 2, an inner conductor 3 disposed inside the hollow outer conductor 2, and a first electrical insulating layer 4 disposed between the inner conductor 3 and the hollow outer conductor 2, where the first electrical insulating layer 4 directly contacts the entire outer surface of the inner conductor 3 and the entire inner surface of the hollow outer conductor tube 2. In the illustrated example, the cable also includes a second electrical insulating layer 5 disposed on the outer surface of the hollow outer conductor 2. For illustrative purposes, each layer of the cable has been cut away in FIGS. 1a and 1b. FIG. 1c shows a cross-section of the cable, showing the solid core conductor 3 coaxially disposed inside the hollow outer conductor 2 and the first insulating layer 4 disposed between the inner conductor and the outer conductor. The outer surface of the outer conductor 2 is covered with a sheath of electrical insulating layer 5.

[0062] FIG. 2 shows a perspective view of a flat-formed coaxial twin-core HV cable 1 including a hollow outer conductor 2, an inner conductor 3 disposed inside the hollow outer conductor 2, and a first electrical insulating layer 4 disposed between the inner conductor 3 and the hollow outer conductor 2, where the first electrical insulating layer 4 is in direct contact with the entire outer surface of the inner conductor 3 and the entire inner surface of the hollow outer conductor tube 2. In the illustrated example, the cable includes a second electrical insulating layer 5 disposed on the outer surface of the hollow outer conductor 2. The outer conductor 2 and the inner conductor 3 are made from extruded metal tubes and assembled as described above, then subjected to a flattening process until the inner tube is completely flattened. After the tube assembly is flattened, the first electrical insulating layer 4 remains in direct contact with the entire outer surface of the inner conductor 3 and the entire inner surface of the hollow outer conductor tube 2. For illustrative purposes, each layer of the cable has been cut away. The flat cable 1 has a large surface area, which improves cooling compared to a non-flat cable. Additionally, flat cables have a smaller height than round cables having the same cross-sectional area.

[0063] FIG. 3 shows an alternative cross-sectional shape of a flat coaxial twin core HV cable 1 in which the inner conductor 3 is a solid extrusion.

[0064] 4a-c show perspective views of different exemplary embodiments of a coaxial-twin HV cable 1 having internal cooling channels 6, 6'. Corresponding to the cable of FIG. 1, the cable 1 includes a hollow outer conductor 2, an inner conductor 3 disposed inside the hollow outer conductor 2, and a first electrical insulating layer 4 disposed between the inner conductor 3 and the hollow outer conductor 2, with the first electrical insulating layer 4 directly contacting the entire outer surface of the inner conductor 3 and the entire inner surface of the hollow outer conductor tube 2. In the illustrated example, the cable includes a second electrical insulating layer 5 disposed on the outer surface of the hollow outer conductor 2. FIG. 4a shows a coaxial-twin HV cable 1 in which the inner conductor includes two separate D-shaped hollow sections extending the entire length of the cable 1. Each D-shaped port has a D-shaped cooling tube 7, 7' disposed therein, forming two separate cooling channels 6, 6' used for the flow and return of the cooling medium. A third electrical insulating layer 8, 8' is disposed between the inner conductor 3 and the cooling tube 7, 7', and the third electrical insulating layer 8, 8' is in direct contact with the entire outer surface of the cooling tube 7, 7' and the entire inner surface of the hollow portion of the inner conductor tube 3. Figure 4b shows a cable similar to Figure 4a, but in this case the cooling tubes 7, 7' are round tubes, and the ports of the inner conductor 3 are correspondingly round. Figure 4c shows a single round cooling tube 7 separated by an inner wall into two cooling channels 6, 6', each with a D-shape. Correspondingly, the hollow portion within the inner conductor also has a round shape. In each example shown in Figures 4a-c, the cooling tubes 7, 7' are made of metal, preferably extruded aluminum.

[0065] 5 shows an alternative cross section of a flattened coaxial twin-core HV cable 1 with internal cooling channels. The flattened shape of the cable 1, which also includes internal cooling channels, provides efficient cooling both externally through increased surface area and internally through active cooling.

Claims

1. A coaxial two-core high voltage (HV) cable (1), a first elongated hollow extruded section of conductive metal forming a first conductor (2); a second elongated extrusion of conductive metal forming a second conductor (3), said second conductor (3) being arranged coaxially inside said first conductor (2); a first electrically insulating layer (4) arranged between the first conductor (2) and the second conductor (3) and coating the outer surface of the second conductor (3) and the inner surface of the first conductor (2); a second electrically insulating layer (5) coating the outer surface of said first conductor (2); A coaxial two-core high voltage (HV) cable (1).

2. 2. A coaxial twin-core HV cable (1) according to claim 1, wherein the second conductor (3) is a solid rod or a hollow section having at least one air gap along its entire length.

3. 3. A coaxial twin-core HV cable (1) according to claim 1 or 2, having a cross-sectional shape selected from the group consisting of circular, round, elliptical, flattened elliptical (stadium), rectangular, oval, square or polygonal.

4. 4. The coaxial twin-core HV cable (1) according to claim 2 or 3, wherein the first electrical insulating layer (4) has a flat cross-sectional shape and is disposed between the first conductor (2) and the second conductor (3), is in direct contact with the outer surface of the second conductor (3) and the inner surface of the first conductor (2), and has a substantially uniform thickness.

5. further comprising at least one cooling channel (6, 6') for the flow of a cooling medium, 5. The coaxial twin-core HV cable (1) according to claim 1, wherein the at least one cooling channel (6, 6') is an extruded metal tube (7, 7') arranged coaxially inside the at least one void of the second conductor (3), and the coaxial twin-core HV cable (1) has a third electrical insulating layer (8, 8') arranged between an outer surface of the at least one cooling tube (7, 7') and an inner surface of the at least one void of the second conductor (3).

6. Two cooling channels (6, 6'), said cooling channels (6, 6') a first cooling channel (6, 6') for the flow of a cooling medium; a second cooling channel (6, 6') for the return flow of said cooling medium; 6. The coaxial twin-core HV cable (1) according to claim 5,

7. 7. A coaxial twin-core HV cable (1) according to claim 6, wherein the two cooling channels (6, 6') are formed by a single extruded cooling tube (7) having two axially extending parallel channels.

8. 7. The coaxial twin-core HV cable (1) according to claim 6, wherein the two cooling channels are formed by two separate extruded tubes (7, 7') extending axially.

9. The coaxial twin-core HV cable (1) according to any one of claims 1 to 8, wherein the first conductor (2) and the second conductor (3) and the at least one cooling tube (7, 7') are made of a metal selected from aluminum, an aluminum alloy, copper or a copper alloy.

10. 10. The coaxial twin-core HV cable (1) according to claim 9, wherein the first conductor (2) and / or the second conductor (3) are made of an alloy of the AA6XXX series or of the AA1XXX series.

11. The coaxial twin-core HV cable (1) according to any one of claims 1 to 10, wherein the material of the first electrical insulation layer, the second electrical insulation layer, and / or the third electrical insulation layer has a dielectric strength of 30 to 70 kV / mm.

12. The coaxial twin-core HV cable (1) according to any one of claims 1 to 10, wherein the material of the second electrical insulating layer has a dielectric strength of 15 to 30 kV / mm.

13. A method for manufacturing a coaxial twin-core high voltage cable (1) according to any one of claims 1 to 12, comprising the steps of: (i) providing a first extruded hollow section (2) of conductive metal and a second extruded section (3) of conductive metal, said second extruded section (3) having a diameter smaller than the inner diameter of the hollow section of said first extruded hollow section (2), said second extruded section (3) being either a solid rod or a hollow section having at least one void along its entire length; (ii) applying a coating layer (4) of a first electrically insulating material to the outer surface of the second extrusion profile (3) to obtain a coated second extrusion profile having a first electrically insulating layer (4); (iii) placing the coated second extruded profile (3) inside the first extruded hollow profile (2); and (a) expanding the coated second extruded tube (3) until the first electrical insulating layer (4) directly contacts and covers the inner surface of the first extruded hollow profile (2); or (b) reducing the cross-sectional diameter of the first extruded hollow profile (2) until the first electrically insulating layer (4) directly contacts and covers the inner surface of the first extruded hollow profile (2); or (c) a combination of both (a) and (b) a step of assembling the first extruded hollow shape member (2) and the second extruded shape member (3) by (iv) applying a coating layer (5) of a second electrically insulating material to the outer surface of the first extruded hollow profile (2); A method comprising:

14. 14. The method according to claim 13, wherein the step of applying the second electrically insulating layer (5) is performed before or after step (iii).

15. - providing at least one cooling tube (7, 7') which is an extruded metal tube; - applying a coating layer (8) of a third electrically insulating material to the outer surface of said at least one cooling pipe (7, 7') to obtain at least one coated cooling pipe (7, 7'); - placing said at least one coated cooling pipe (7, 7') inside said second extruded hollow profile (3) having at least one void; and - expanding the at least one coated cooling pipe (7, 7') until the third electrical insulating layer (8) on the outer surface of the at least one cooling pipe is in direct contact with and covers the inner surface of the cavity of the second extruded hollow profile (3), or - reducing the diameter of the cross section of the second extruded hollow profile (3) until the third electrical insulating layer (8) on the outer surface of the at least one cooling pipe (7, 7') is in direct contact with and covers the inner surface of the cavity of the second extruded hollow profile (3); performing one or both of the steps 15. The method of claim 13 or 14, further comprising:

16. The method according to any one of claims 13 to 15, further comprising the step of flattening the cable (1).

17. 17. The method according to any one of claims 13 to 16, wherein the first extruded hollow profile (2), the second extruded profile (3) and the at least one cooling pipe (7, 7') are made of a metal selected from aluminum, an aluminum alloy, copper or a copper alloy, preferably aluminum or an aluminum alloy.

18. Use of a coaxial twin-core high voltage (HV) cable (1) according to any one of claims 1 to 12 for transmitting power at high voltage in a hybrid electric vehicle (HEV), or in an electric vehicle (EV), or as a charging cable in a charging unit or charging station, or in a charging station infrastructure, or in an electric or hybrid electric ship, or in a data center, or in a wind turbine or wind turbine park, or in a PV system.

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