High-voltage cable

Abstract

It is disclosed a high-voltage cable for an electric vehicle, an electric vehicle comprising the high- voltage cable, and a method of making same. The high-voltage cable comprises: - a first conductor (130), wherein the first conductor (130) is an extruded hollow profile with an outer surface and an inner surface; - a first heat pipe (110) comprising an evaporation zone (ZE), an adiabatic zone (ZA), and a condensation zone (ZC), - a first electrically insulating layer (120) applied on an outer surface of the heat pipe (110); and - a second electrically insulating layer (140) applied on the outer surface of the first conductor (130); wherein the condensing zone (ZC) is arranged outside the conductor (130), and the evaporation zone (ZE) is arranged inside the first conductor (130).

Description

[0001] High-voltage cable

[0002] TECHNICAL FIELD

[0003] The present invention relates to high-voltage cables, and in particular cooled charging cables for electric vehicles. Furthermore, the invention relates to a method for manufacturing of the high- voltage cable.

[0004] BACKGROUND ART

[0005] In the field of hybrid electric vehicles (HEV) and battery electric vehicles (BEV), high-voltage (HV) cables are inter alia used to output power from the battery to the drive motor; and when the battery needs to be re-charged, HV cables are also used to supply power to the battery. A first HV cable, usually flexible, temporarily connects the charging unit / station to the vehicle's charging port. A second HV cable, usually rigid, permanently connects the charging port to the battery. As such, the battery can be connected to the charging station for re-charging.

[0006] Development of the battery electric vehicle technology has led to a demand for faster battery charging, particularly at public charging stations. At higher currents, the conducting material tends to become very hot which cause its resistance to increase, which in turn slows down the charging process. One way of mitigating this effect is to increase the cross-sectional area of the conductor. However, there is a continuous strive to reduce the weight of all components in vehicles. Therefore, it is a limit to how much the size of the HV cables can be increased.

[0007] This issue has been addressed in WO2023 / 111355. It is there disclosed a high-voltage cable, comprising a hollow conductor, wherein an inner metal tube is arranged inside the hollow conductor, and a first electrically insulating layer is arranged between the inner metal tube and the hollow conductor, wherein the first electrically insulating layer is in direct contact with the entire outer surface of the inner tube and the entire inner surface of the hollow conductor tube. By the provision of the inner metal tube the first electrically insulating layer can be held in place on the inside of the hollow conductor, and due to the inward electrical insulation in the hollow conductor the cable can be cooled by means of cooling fluid flowing through the interior of the inner tube. Interior cooling of a high-voltage cable allows for smaller cable cross-sectional area as compared to solid non-cooled high-voltage cables used for the same voltage application.

[0008] HV cables with active cooling by means of a fluid flow would typically also require additional components which will increase the weight of the vehicle (e.g. pump, compressor, valve, heat exchange circuit outside the HV cable).

[0009] The present invention is directed to a high-voltage cable that may solve or at least reduce at least one of the aforementioned problems or challenges.

[0010] SUMMARY OF INVENTION

[0011] The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention.

[0012] The present disclosure relates to a high-voltage cable for an electric vehicle. The high-voltage cable comprises: a first conductor, wherein the first conductor is an extruded hollow profile with an outer surface and an inner surface; a first heat pipe comprising an evaporation zone, an adiabatic zone, and a condensation zone, a first electrically insulating layer applied on an outer surface of the heat pipe; and a second electrically insulating layer applied on the outer surface of the first conductor. Wherein the condensing zone is arranged outside the conductor, and the evaporation zone is arranged inside the first conductor.

[0013] It is thus provided a cooled high-voltage cable. The heat pipe will transport heat away from the conductor such that the temperature inside the high-voltage cable is reduced. By reducing the temperature in the conductor, the electric resistance in the conductor will be reduced. As such an improved charging capacity can be achieved. The amperage can then be increased while maintaining the electric resistance in the conductor (or at least with a limited increase in the electric resistance). The high-voltage cable can thus facilitate an increased charging speed when used in a circuit connecting a battery and a charger.

[0014] It is achieved a cooled high-voltage cable that does not require fluid lines to be connected directly to a cooling tube inside the cable. The working fluid of the heat pipe will always be contained within the heat pipe. The present high-voltage cable is therefore safer and less complex as compared to high-voltage cables being cooled by means of an internal fluid flow, wherein the cooling fluid could lead to short circuit and damage to equipment and people if it comes into contact with the conductor.

[0015] The condensation zone may be cooled by ambient air. As such the high-voltage cable does not rely on additional components that would increase the weight and complexity of the vehicle.

[0016] During a charging process, the high-voltage cable should preferably be maintained at a temperature (Tc) that is less than 50 K warmer than the ambient air temperature (Ta), i.e. the temperature of the high-voltage cable can follow the formula Tc < Ta + 50 K. The temperature in the high-voltage cable should preferably not exceed 125 °C.

[0017] The high-voltage cable will typically be used in applications with a voltage above 230 V, e.g. in the range 300 V - 600 V, or in the range 600 V - 800 V, or in the range 800 V to 1.0 kV, or in the range 1.0 kV - 1.2 kV, or in the range 1.2 kV - 1.5 kV, or in a range up to 2.5 kV.

[0018] The cable may have a cross-sectional area of e.g. 70-500 mm2or 70-200 mm2or 70-120 mm2. Due to the smaller cross-sectional area, the cost and weight can be considerably reduced. It should be understood that other cross-sectional areas and dimensions can be realized for different applications. In the present context, the cable cross-section area refers to the cross-sectional area of the conductor.

[0019] The parts of the heat pipe arranged outside the conductor will typically be arranged outside the outermost layer of the high-voltage cable.

[0020] A heat pipe is a heat-transfer device known in the art. Heat pipes can be made in different shapes and sizes and are typically available in sizes from 2-12 mm diameter, e.g. 6 mm, 8 mm, or 10 mm. Heat pipes can be bent in any direction, allowing them to manoeuvre around components. The heat pipe can thus be adapted to the shape of the high-voltage cable. However, bends may negatively affect the performance of the heat pipe, i.e. reduce their heat transferring performance.

[0021] The heat pipe of the high-voltage cable may be straight, i.e. without bends. A heat pipe comprises an evaporation zone, an adiabatic zone, and a condensation zone, wherein the adiabatic zone is arranged between the evaporation zone and the condensation zone. A heat pipe comprises a working fluid arranged to transport thermal energy within the heat pipe.

[0022] In the evaporation zone, the working fluid inside the heat pipe evaporates to vapor by absorbing thermal energy, i.e. absorbing heat from the outside of the heat pipe. In the present high-voltage cable, the evaporation zone is arranged to absorb thermal energy from the conductor. In the condensation zone, the working fluid condenses back to a liquid by releasing thermal energy, i.e. releasing heat to the outside of the heat pipe. In the present high-voltage cable, the condensation zone is arranged to release heat away from the conductor.

[0023] The high-voltage cable can comprise a plurality of heat pipes regardless of the number of conductors in the high-voltage cable.

[0024] The electrically conducting metal forming the conductor may be selected from aluminium, aluminium alloy, copper, or copper alloy. It is preferred that the conducting metal is aluminium or aluminium alloy as aluminium will significantly reduce the weight of the cable compared with Cu. In addition, aluminium has lower cost compared with Cu, and may also be a more sustainable choice of material. Particularly suitable aluminium alloys for the inner and outer conductors are AA6XXX -series aluminium alloys, AA3XXX-series aluminium alloys, and AAlXXX-series aluminium alloys. In the present disclosure, reference to AA1XXX, AA3XXX and AA6XXX-series aluminium alloys refer to the nomenclature of the Aluminum Association which uses a four-digit system for wrought alloy composition families (ref. "International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys", by The Aluminum Association, Inc).

[0025] The conductor is thus a rigid conductor.

[0026] The evaporation zone of the heat pipe is preferably in tight thermal contact with the conductor for optimal heat transfer. However, the heat pipe and the conductor must be electrically insulated from each other by a thermally insulating layer. As an example, the heat pipe and the conductor can be squeezed together after insertion of the heat pipe inside the conductor.

[0027] One heat pipe can extend through the entire length of the conductor or at least substantially the whole length of the conductor. Alternatively, two or more heat pipes may be arranged such that they together extend through the entire length of the conductor or at least substantially the whole length of the conductor.

[0028] High-voltage cables need to be outwardly insulated to prevent contact of conductor with other objects or people. The cable therefore comprises a second electrically insulating layer arranged on the outside surface of the conductor, preventing undesired short circuit and other damage. The material of the second electrically insulating layer is suitably a non-conductive polymeric material, and may have a lower dielectric strength than the material of the first electrically insulating layer, such as e.g. 15-30 kV / mm, or 20-25 kV / mm. The material of the first electrically insulating layer may be the same as the second insulating layer. The requirement for good heat transfer may not be so high on the conductor outside, and the second electrically insulating layer may therefore have a higher material thickness than the first electrically insulating layer. For example, the second electrically insulating layer may be made of a polymeric material, such as polyamide or polyethylene, such as XLPE, preferably a polyamide or a cross-linked polypropylene, which has a considerably lower cost than materials having higher dielectric strength. The second electrically insulating layer may not be permanently adhered to the surface of the conductor, in order to allow it to be peeled off for electrical connecting purposes. The first electrically insulating layer is made of a non-electrically conductive material that is suitably capable of withstanding bending and suitably has a sufficient dielectric strength, preventing current passing between the conductor and the heat pipe. The material of the first electrically insulating layer preferably has a dielectric strength of 30-70 kV / mm, more preferably at least 40 kV / mm. Thereby, the first electrically insulating layer can be made relatively thin to allow efficient heat transfer from the conductor, while at the same time provide sufficient electrical insulation. The material of the first electrically insulating layer may be a polymeric material, for example a polyethylene or a polyamide, such as PA12 or the like, which has sufficient dielectric strength and therefore can be made thin enough to provide efficient heat transfer from the conductor to the heat pipe. Other advantageous properties of the first electrically insulating layer material are good adhesion properties and flame retardancy and good thermal conductivity.

[0029] A first electrically insulating layer can be applied on the inner surface of the first conductor and / or on the outer surface of the heat pipe. The purpose of the first electrically insulating layer is to electrically insulate the conductor from the heat pipe.

[0030] The heat pipe will typically be arranged such that the adiabatic zone is at least partly outside the first conductor.

[0031] Heat does not enter or leave the heat pipe in the adiabatic zone. In the present high-voltage cable, the adiabatic zone is arranged in a position where neither absorbing nor releasing heat is desirable, typically extending from the inside of the conductor to the outside of the conductor.

[0032] The adiabatic zone will typically extend at least partly outside the conductor to arrange the condensing zone at a preferred position for cooling the working liquid.

[0033] The heat pipe can be routed out through one end of the conductor or through a hole in the conductor wall. If the conductor is bent, the hole may preferably be located at a bend. The circumference of the hole is preferably applied an electrically insulating layer corresponding to the first / second insulating layer.

[0034] The condensation zone is routed out of and away from the conductor to a place where it can be cooled, preferably by means of active cooling.

[0035] The condensation zone can have a different shape or diameter than the evaporation zone to enable efficient cooling, e.g. a bigger cross-section or be provided with cooling ribs. The condensation zone may be configured for active cooling for example with water or a refrigerant flow or by fans. The active cooling can also be provided by means of contact with an actively cooled body. The actively cooled body can be configured to be mechanically latched to the high-voltage cable. The actively cooled body can be part of the charging cable connector, the electric vehicle, or the high-voltage cable itself.

[0036] The surface of the evaporator zone is coated with electrical insulation.

[0037] The high-voltage cable is preferably configured such that in use the condensation zone is arranged at a higher vertical elevation than the evaporation zone. In this case the inside of the heat pipe can be smooth, i.e. the wick can be omitted.

[0038] Arranging the condensation zone at a higher vertical elevation than the evaporation zone will positively affect the performance of the heat pipe, i.e. increase its heat transferring performance.

[0039] In use, e.g. in an electric vehicle, the high-voltage cable will often connect two points of different vertical elevation. The arrangement of the heat pipe(s) should take this into consideration. The heat pipe(s) may for example extend through a certain length of the conductor and extend out of the conductor at the end having the highest vertical elevation. In cases where the conductor is bent in such a way that one or more bends have a higher vertical elevation than both ends of the conductor, it would be preferred to arrange the heat pipe to extend out of the conductor at one of these bends, i.e. through the conductor wall at this location.

[0040] The heat pipe may comprise a wick providing a capillary effect such that a condensed working fluid can be transported from the condensation zone towards the evaporation zone. The wick properties such as thickness and porosity can be adapted according to thermal requirements. Arranging the heat pipe such that the wick must work against gravity will negatively affect the performance of the heat pipe, as compared to arranging the heat pipe such that the wick works horizontally or at least partly in the same direction as gravity.

[0041] However, the wick can allow the high-voltage cable to be used with the condensation zone arranged at a lower vertical elevation than the evaporation zone. This may be beneficial if the high-voltage cable cannot be arranged with the condensation zone arranged at a higher vertical elevation than the evaporation zone, e.g. due to the positioning of the other components in an electric vehicle. As an example, the battery may be positioned at a higher vertical elevation than the charging port.

[0042] An advantage of arranging the condensation zone at a lower vertical elevation than the evaporation zone is that connection points for the cooling fluids used for cooling the battery will typically be available in the same area.

[0043] The high-voltage cable may comprise: a first end configured to be connected to a battery; and a second end, opposite the first end, configured to be connected to a charging port or a charging cable connector.

[0044] The battery can be a battery for an electric vehicle, such as a battery electric vehicle.

[0045] The charging port may be an electric vehicle inlet, such as an IEC 62196 Type 2 connector (male).

[0046] The charging cable connector may be an IEC 62196 Type 2 connector (female).

[0047] The ends of the conductor may be shaped to form separate connections. In a preferred embodiment the connections are integrated with the conductor.

[0048] The high-voltage cable may comprise a cable shoe connected to the first end and / or the second end.

[0049] The evaporation zone is preferably arranged to absorb thermal energy from the first end and / or the second end of the high-voltage cable.

[0050] During a charging process, the highest temperatures are normally seen in the connection points of the high-voltage cable, i.e. at the first end and the second end.

[0051] The heat pipe preferably extends out of the first conductor at the first end or the second end of the high-voltage cable.

[0052] Alternatively, the heat pipe can extend out of the conductor at a bend of the high-voltage cable.

[0053] The high-voltage cable may comprise a plurality of heat pipes.

[0054] The high-voltage cable may comprise: a second heat pipe comprising an evaporation zone, an adiabatic zone, and a condensation zone. Wherein the condensing zone is arranged outside the first conductor, and the evaporation zone is arranged inside the first conductor. Wherein the evaporation zone of the first heat pipe is arranged to absorb thermal energy from the first end of the conductor and the evaporation zone of the second heat pipe is arranged to absorb thermal energy from the second end of the conductor.

[0055] If two heat pipes are used in the same high-voltage cable, the first heat pipe can extend out of the conductor at the first end of the high-voltage cable and the second heat pipe can extend out of the conductor at the second end of the high-voltage cable. The two heat pipes can in that way be arranged to cool respective end portions of the conductor.

[0056] If the high-voltage cable is bent in at least two places and comprises a second heat pipe, the first heat pipe can extend out of the conductor at the first bend and the second heat pipe can extend out of the conductor at the second bend.

[0057] The high-voltage cable may comprise: a second conductor, wherein the second conductor is an extruded hollow profile with an outer surface and an inner surface; and a third electrically insulating layer applied on the outer surface of the second conductor.

[0058] The first conductor may be arranged coaxially inside the second conductor.

[0059] If the first conductor is arranged coaxially inside the second conductor, the second electrically insulating layer is arranged between the first conductor and the second conductor. The second electrically insulating layer is then preferably arranged on the outer surface of the first conductor, i.e. in direct contact with the outer surface of the first conductor and the inner surface of the second conductor.

[0060] When arranged coaxially, the first conductor and the second conductor can respectively be referred to as an inner conductor and an outer conductor.

[0061] Alternatively, two conductors can be arranged side-by-side in the high-voltage cable. The high- voltage cable would then preferably comprise a second heat pipe arranged with the evaporation zone inside the second conductor and the condensing zone outside the second conductor, i.e. a corresponding arrangement as the first heat pipe. The two heat pipes would then be covered by separate electrically insulating layer.

[0062] Regardless of the two conductors are coaxially arranged or not, the first conductor can be used for plus current, and the second conductor can be used for minus current, or vice versa.

[0063] The conductor will typically comprise one hollow chamber extending through a longitudinal direction of the extruded hollow profile, the at least one hollow chamber having openings at opposite ends of the extruded hollow profile.

[0064] Alternatively, the conductor can comprise two or more hollow chambers extending through the longitudinal direction of the extruded hollow profile, the hollow chambers having openings at opposite ends of the extruded hollow profile. The high-voltage cable can then comprise one or more heat pipes per hollow chamber, wherein the evaporation zone of at least one heat pipe is arranged in each hollow chamber.

[0065] The high-voltage cable can have a cross-sectional shape selected from circular, rounded, oval, flattened oval (stadium shaped), rectangular, oblong, quadratic, or polygonal. However, significantly flattening may negatively affect the performance of the heat pipe.

[0066] The high-voltage cable may comprise a shielding. The shielding is arranged as an outermost layer on the high-voltage cable and made of metal to avoid electric noise due to magnetic fields. The shielding may be a braided layer or, more preferably, a layer obtained in the form of an extruded tube, which can be applied by inserting the insulated conductor into an extruded tube intended to form the shield. If desired, a polymer coating may be provided on the surface of the shielding. The outer coating on the surface of the shielding may be a polyamide. Such a coating can have a specific colour to indicate the type of high-voltage cable.

[0067] The high-voltage cable may be a shielded busbar.

[0068] Dual-core cables with coaxially arranged inner and outer conductors don't need shielding because the electrical fields are balanced out.

[0069] The conductor(s) and heat pipe(s) can have a circular cross-section or a polygonal cross-section, e.g. rectangular.

[0070] The high-voltage cable may comprise a cooling system. The cooling system can be an active cooling system or a passive cooling system.

[0071] The present disclosure also relates to an electric vehicle.

[0072] The electric vehicle comprises: a high-voltage cable as described herein; a battery; and a charging port. Wherein the high-voltage cable at a first end is connected to the battery and at a second end is connected to the charging port.

[0073] The high-voltage cable may be connected to the battery and / or charging port by means of one or more connector(s).

[0074] The battery is configured to supply power to a motor operating the electric vehicle.

[0075] The charging port is configured to receive a charging cable connector, e.g. a IEC 62196 Type 2 connector.

[0076] The charging port is typically arranged at a higher vertical elevation than the battery.

[0077] The electric vehicle can be any means for carrying or transporting something, such as cars, bicycles, boats, planes, and trains.

[0078] The electric vehicle may preferably comprise a cooling system for cooling of the condensation zone of the heat pipe. The cooling system can be an active cooling system or a passive cooling system.

[0079] The cooling system may comprise a flow line, wherein the flow line is configured to absorb heat from the condensation zone. The flow line may use any appropriate refrigerant / fluid. CO2, water and a water / glycol mixture are examples of common refrigerants. The cooling system may comprise one or more fans, wherein the fans are arranged to provide an airflow on the condensation zone. The cooling system may be configured to also cool the battery.

[0080] The condensation zone can be configured to extend into the flow line such that the outer surface of the condensation zone is in contact with the refrigerant. The condensation zone is preferably configured to extend into the flow line in a sealing manner, i.e. preventing refrigerant from leaking out from the flow line, and without the refrigerant entering the inside of the heat pipe. The heat pipe can be provided with a latching mechanism for connection to the fluid line. The heat pipe and / or the flow line can be provided with a seal (e.g. an elastomeric seal such as an o-ring or gasket) to prevent leakage of the refrigerant at the interface between the heat pipe and the flow line. The electric vehicle can comprise an actively cooled body or the charging cable connector can comprise an actively cooled body. The condensation zone of the heat pipe can then be mechanically connected to the actively cooled body.

[0081] The cooling system may comprise a phase changing material (PCM).

[0082] The present disclosure also relates to a method for manufacturing the high-voltage cable described herein.

[0083] The method comprises the steps of: providing a first conductor by means of extruding a hollow profile comprising a hollow chamber extending through a longitudinal direction of the first conductor; providing a heat pipe comprising an evaporation zone, an adiabatic zone, and a condensation zone, wherein the evaporation zone has a diameter which is smaller than an inner diameter of the hollow chamber; applying a first electrically insulating layer onto an outer surface of the heat pipe and / or an inner surface of the hollow chamber; and assembling the first conductor and the heat pipe by placing the evaporation zone of the heat pipe inside the hollow chamber and crimping the first conductor or expanding the heat pipe to provide a tight fit between the heat pipe and the first conductor.

[0084] The first conductor can be crimped by any appropriate means known in the art, e.g. swaging, drawing, roll forming, or pressing. Both the inner diameter of the hollow chamber and the outer diameter of the conductor will then typically be reduced.

[0085] The heat pipe can be expanded by any appropriate means known in the art.

[0086] The electrically insulating layers may be applied on the appropriate surface by any suitable method, e.g. co-extrusion, powder coating, using adhesion or other method known to the skilled person. The material of the electrically insulating layer may be applied so as to obtain permanent adhesion between the conductor / heat pipe and the insulating layer, such as chemical adhesion, e.g. by applying a primer or glue to the surface before applying the insulating layer, or any other suitable pre-treatment.

[0087] Before the assembling step, the method may comprise the steps of:

[0088] - bending the first conductor at one or more positions to achieve a predetermined shape;

[0089] - making a hole in one or more of the bent positions of the first conductor; and

[0090] - entering the evaporation zone into the hollow chamber through the hole in the first conductor wall.

[0091] The cable can be bent by means of a bending tool.

[0092] The hole must have a larger diameter than the heat pipe.

[0093] The method preferably comprises applying an electrically insulating layer on the circumference of the hole made in the conductor wall to isolate the heat pipe from the conductor. The electrically insulating layer may correspond to the first electrically insulating layer.

[0094] The predetermined shape may correspond to a path between a battery and a charging port inside an electric vehicle. The predetermined shape should be set such that the high-voltage cable does not collide with the positioning of other components in the electric vehicle. Alternatively, the high-voltage cable can be bent into a predetermined shape after the assembling step.

[0095] The method may comprise the steps of flattening one or both ends of the first conductor.

[0096] The method may comprise the step of attaching a connector to one or both ends of the first conductor.

[0097] The method may also comprise the step of providing a hole in the flattened end(s). The hole can be used for attaching the end by means of a bolt or similar.

[0098] The method may comprise the steps of:

[0099] - applying a second electrically insulating layer onto an outer surface of the first conductor; and

[0100] - applying a shielding as an outermost layer on the high-voltage cable.

[0101] The method may comprise the steps of:

[0102] - providing a second conductor by means of extruding a hollow profile comprising a hollow chamber extending through a longitudinal direction of the second conductor, wherein the hollow profile has an inner diameter which is larger than the outer diameter of the first conductor;

[0103] - applying a second electrically insulating layer onto an outer surface of the first conductor and / or an inner surface of the hollow chamber of the second conductor; and

[0104] - assembling the second conductor and the first conductor by coaxially arranging the first conductor inside he second conductor and crimping the first conductor or expanding the heat pipe to provide a tight fit between the first conductor and the second conductor.

[0105] BRIEF DESCRIPTION OF DRAWINGS

[0106] The following drawings are appended to facilitate the understanding of the invention. The drawings show embodiments of the invention, which will now be described by way of example only, where:

[0107] Fig. 1 is a cross-sectional view illustrating the working principle of a heat pipe comprising an evaporation zone, an adiabatic zone, and a condensation zone;

[0108] Fig. 2a is a perspective view of a high-voltage cable comprising a heat pipe, a first electrically insulating layer outside the heat pipe, a hollow conductor, and a second electrically insulating layer outside the conductor, wherein the layers are partly removed for illustrative purposes;

[0109] Fig. 2b is a side view of the high-voltage cable of Fig. 2a;

[0110] Fig. 2c is a cross-sectional view of the high-voltage cable of Fig. 2a;

[0111] Figs. 3 is a cross-sectional view of a high-voltage cable comprising a heat pipe, a first electrically insulating layer outside the heat pipe, a hollow conductor, and a second electrically insulating layer outside the conductor, and a shielding;

[0112] Figs. 4 is a cross-sectional view of a high-voltage cable comprising two conductors arranged coaxially;

[0113] Figs. 5 is a cross-sectional view of a high-voltage cable comprising two conductors arranged side-by- side; Fig. 6 is a schematic illustration of an electric vehicle comprising a battery, a charging port, and a high- voltage cable connecting the charging port to the battery;

[0114] Fig. 7 is a schematic illustration of an electric vehicle comprising a battery, a charging port, a high- voltage cable, and a cooling system for cooling the high-voltage cable;

[0115] Fig. 8 is a schematic illustration of a high-voltage cable arranged in an electric vehicle, wherein the heat pipe extends through the end of the high-voltage cable to be cooled by the cooling system;

[0116] Fig. 9 is a schematic illustration of a high-voltage cable arranged in an electric vehicle, wherein the heat pipe extends through the wall of the high-voltage cable to be cooled by the cooling system;

[0117] Fig. 10 is a schematic illustration of a high-voltage cable arranged in an electric vehicle, wherein two heat pipes extend through the wall of the high-voltage cable to be cooled by the cooling system;

[0118] Fig. 11 is a schematic illustration of a high-voltage cable arranged in an electric vehicle, wherein two heat pipes extend through the ends of the high-voltage cable to be cooled by the cooling system;

[0119] Fig. 12 is a schematic illustration of a high-voltage cable arranged in an electric vehicle, wherein the heat pipe is arranged with the condensation zone at a lower position than the evaporation sone; and

[0120] Fig. 13 is a schematic illustration of a high-voltage cable arranged in an electric vehicle, wherein the heat pipe is arranged with the condensation zone at a lower position than the evaporation sone.

[0121] DETAILED DESCRIPTION

[0122] In the following, embodiments of the invention will be discussed in more detail with reference to the appended drawings. It should be understood, however, that the drawings are not intended to limit the invention to the subject-matter depicted in the drawings.

[0123] Throughout the description and claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise. The phrase "in one embodiment" as used herein does not necessarily refer to the same embodiment, although it may. Furthermore, the phrase "in another embodiment" as used herein does not necessarily refer to a different embodiment, although it may. Thus, as described below, various embodiments of the invention may be readily combined, without departing from the scope of the invention.

[0124] In addition, 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 being based on additional factors not described, unless the context clearly dictates otherwise. In addition, throughout the specification, the meaning of "a", "an", and "the" include plural references. The meaning of "in" includes "in" and includes plural references. The meaning of "in" includes "in" and "on."

[0125] The present disclosure aims at providing a cooled high-voltage cable (hereafter also denoted "cable"). The described cable is suitable for applications where the voltage is from 300-1200 V, e.g. in electrical vehicles, however the cable can be used with other voltage ranges, e.g. up to 2500 V and even higher. The cable has excellent cooling, thus avoiding heat build-up in the cable, particularly in the conductor. The cable is especially suitable for installation in battery electrical vehicles or hybrid electrical vehicles. The cable is also suitable for connection to a charging cable in a charging unit or charging station, or for use in charging station infrastructure. Other suitable applications of the cable are electrical vessels or hybrid electrical vessels, such as marine vessels, ships and boats, data centres, windmills, PV systems, and any other installations requiring cables for high-voltage transfer.

[0126] Fig. 1 shows a cross-sectional view of a heat pipe 110. A heat pipe 110 is a heat-transfer device used in a variety of applications, e.g. for cooling of laptops. Inside the heat pipe 110, a working fluid evaporates by absorbing heat from the source that needs cooling. The evaporated fluid moves through a vapor cavity 113 of the heat pipe 110 to a position where heat can be released by condensing the work fluid. The condensed work fluid then moves through the heat pipe 110 to be evaporated again. To facilitate movement of the condensed working fluid, a wick 112 is provided inside a casing 111 of the heat pipe 110. The cyclic movement of the work fluid is indicated with arrows. The heat pipe 100 can be divided into an evaporation zone Zfwhere heat is absorbed, a condensation zone Zcwhere heat is released, and an adiabatic zone ZAconnecting the evaporation zone ZEand the condensation zone Zc. Condensation of the work fluid can be improved by means of active cooling of the condensation zone Zc.

[0127] Heat pipes 110 can be shaped to fit specific purposes. In Fig. 1 the heat pipe 110 is schematically illustrated and does not necessarily reflect the shape of a typical heat pipe 110.

[0128] Fig. 2a shows a perspective view of a high-voltage cable 100 comprising a heat pipe 110. The high- voltage cable 100 also comprises a conductor 130. The conductor 130 is an extruded hollow profile with an outer surface and an inner surface.

[0129] During use, the conductor 130 heats up. The heat pipe 110 is arranged inside the conductor 130 to absorb some of that heat for the conductor 130 to maintain a desired operating temperature. The heat pipe 110 transports the heat away from the conductor 130 before it is released.

[0130] The conductor 130 and the heat pipe 110 are separated by a first electrically insulating layer 120. A second electrically insulating layer 140 is provided on the outer surface of the conductor 130. The heat pipe 110, the first electrically insulating layer 120, the conductor 130, and the second electrically insulating layer 140 are arranged coaxially and tightly fitted to each other.

[0131] In Fig. 2a the high-voltage cable 100 is schematically illustrated and does not necessarily reflect the dimensions of a typical high-voltage cable 100.

[0132] Fig. 2b and Fig. 2c respectively show a side view and a cross-sectional view of the high-voltage cable of Fig. 2a.

[0133] Figs. 3-5 show cross-sectional views of some exemplifying high-voltage cables 100.

[0134] Figs. 3 shows a cross-sectional view of a high-voltage cable 100 having all the features of the cable shown in Fig. 2c and additionally a shielding 150. The shielding is arranged outside the second electrically insulating layer 140.

[0135] Figs. 4 shows a cross-sectional view of a high-voltage cable 100 having all the features of the cable shown in Fig. 2c and additionally a second conductor 160 and a third electrically insulating layer 170. The second conductor 160 and the first conductor 130 are coaxially arranged. The third electrically insulating layer 170 is arranged outside the second conductor 160. This high-voltage cable 100 can also be provided with a shielding 150.

[0136] Figs. 5 shows a cross-sectional view of a high-voltage cable 100 comprising two conductors 130 arranged side-by-side. The high-voltage cable 100 further comprises two heat pipes 110 arranged with their evaporation zones ZEinside respective conductors 130, and each covered by a separate first electrically insulating layer 120. The two conductors 130 can be covered by a mutual second electrically insulating layer 140 as shown, or alternatively be covered by one electrically insulating layer each. This high-voltage cable 100 can also be provided with a shielding 150.

[0137] Fig. 6 shows a schematic illustration of an electric vehicle 1. The electric vehicle 1 is in this example a car. The electric vehicle 1 comprises a battery 200 located in a lower part of the electric vehicle 1. The electric vehicle 1 also comprises a charging port 300 located at a higher position than the battery 200. The electric vehicle 1 further comprises a high-voltage cable 100 of the type described above. The high-voltage cable 100 is connected to the battery 200 at a first end 100' and to the charging port 300 at a second end 100".

[0138] Fig. 7 shows a schematic illustration of an electric vehicle 1 like the one in Fig. 6 which additionally comprises a cooling system 400 for cooling the high-voltage cable 100. The high-voltage cable 100 is arranged such that the condensation zone Zc of its heat pipe(s) is / are cooled by the cooling system 400. The high-voltage cable 100 will produce heat during use, which in this example is when the battery 200 is being charged. When the high-voltage cable 100 is not used, the cooling system 400 can be turned off. The cooling system 400 can be dedicated to the high-voltage cable 100 or it could be used to exchange heat with other parts of the electric vehicle 1, e.g. heating a passenger space.

[0139] The high-voltage cable 100 can be provided with connectors 180 in the first end 100' and the second end 100". The connectors 180 may be of different types, e.g. configured to interface the battery 200 or the charging port 300.

[0140] Fig. 8-13 show schematic illustrations of high-voltage cables 100 and their arrangement in an electric vehicle 1, and the arrangement of the heat pipe(s) 110. The vehicle 1 itself is hidden for clarity.

[0141] In Fig. 8, the heat pipe 110 extends from the first end 100' of the high-voltage cable 100 through the second end 100" of the high-voltage cable 100 (i.e. through the entire length of the conductor 130) and into contact with the cooling system 400. The evaporation zone Zfof the heat pipe 110 is arranged inside the conductor 130 and the condensation zone Zc of the heat pipe 110 is in contact with the cooling system 400. The evaporation zone ZEis arranged to absorb heat from the entire conductor 130 and the entire condensation zone Zc is in contact with the cooling system 400. The adiabatic zone ZAof the heat pipe 110 extends the part of the heat pipe 110 that is neither inside the conductor 130 nor in contact with the cooling system 400.

[0142] The heat pipe 110 and the conductor 130 illustrated in Fig. 8 are bent correspondingly. A straight heat pipe 110 is then placed inside a hollow chamber of a straight conductor 130 before the two are bent simultaneously. Before the bending operation the heat pipe 110 and the conductor 130 should be assembled by means of crimping the conductor 130 or expanding the heat pipe 110 to provide a tight fit between them. The high-voltage cable 100 may have a plurality of bends. In some applications the high-voltage cable 100 may also be straight. If the high-voltage cable 100 is straight, the heat pipe 110 and the conductor 130 should still be assembled to each other. How the high-voltage cable 100 is bent will typically depend on the placement of the components it is connecting and the relative placement of surrounding components.

[0143] In Fig. 9, the conductor 130 is bent while the heat pipe 110 is straight. The heat pipe 110 extends through a straight portion of the conductor 130 and through the wall of conductor 130 at a bend. A hole then needs to be made in the conductor 130 after bending. The heat pipe 110 is entered into the hollow chamber of the conductor 130 through the hole and then fitted to the conductor 130. This alternative will reduce the cross-section of the conductor 130 and thus reduce its performance. In Fig. 9, the condensation zone Zc is positioned higher than the evaporation zone Zf. Gravity will then urge the condensed work fluid towards the evaporation zone Zf. This will positively affect the heattransferring performance of the heat pipe 110.

[0144] In Fig. 10, two heat pipes 110 are used to cool the same conductor 130. Like in Fig. 9, the heat pipes 110 are straight and need to be fitted after the conductor 130 is bent. The heat pipes 110 are cooling one straight portion of the conductor 130 each. In this configuration the heat pipes 110 are arranged to cool portions close to the connection points of the high-voltage cable 100. These are areas where a lot of heat is typically generated during a charging process. The two heat pipes 110 may be cooled by the same or separate cooling systems 400. Fig. 11 shows an alternative to the configuration of Fig. 10. Instead of extending through the conductor 130 wall, the heat pipes 110 extend through the first end 110' and the second end 100" of the conductor 130. If connectors 180 are provided at the ends 100', 100" the heat pipes 110 will extend through the connectors 180.

[0145] In Fig. 11, the heat pipes 110 are horizontally arranged. The wick 112 will then facilitate movement of the condensed work fluid towards the evaporation zone Zf.

[0146] Fig. 12 and Fig. 13 show configurations corresponding to Fig. 9 and Fig. 8, except that the heat pipe 110 exits the conductor 130 at a lower position such that the condensation zone Zc is at a lower position than the evaporation zone Zf. The wick 112 will facilitate movement of the condensed work fluid towards the evaporation zone Zf. However, the movement will be slowed down by gravity.

[0147] LIST OF REFERENCE NUMBERS

[0148] 1 Electric vehicle

[0149] 100 High-voltage cable

[0150] 100' First end of high-voltage cable

[0151] 100" Second end of high-voltage cable

[0152] 110 Heat pipe

[0153] 111 Casing

[0154] 112 Wick

[0155] 113 Vapor cavity

[0156] 120 First electrically insulating layer

[0157] 130 First conductor

[0158] 140 Second electrically insulating layer

[0159] 150 Shielding

[0160] 160 Second conductor

[0161] 170 Third electrically insulating layer

[0162] 180 Connector

[0163] 200 Battery

[0164] 300 Charging port

[0165] 400 Cooling system

[0166] ZA Adiabatic zone

[0167] ZcCondensation zone

[0168] Zf Evaporation zone

Claims

CLAIMS1. A high-voltage cable (100) for an electric vehicle (1), wherein the high-voltage cable (100) comprises:- a first conductor (130), wherein the first conductor (130) is an extruded hollow profile with an outer surface and an inner surface;- a first heat pipe (110) comprising an evaporation zone (ZE), an adiabatic zone (ZA), and a condensation zone (Zc),- a first electrically insulating layer (120) applied on an outer surface of the heat pipe (110); and- a second electrically insulating layer (140) applied on the outer surface of the first conductor (130); wherein the condensing zone (Zc) is arranged outside the conductor (130), and the evaporation zone (ZE) is arranged inside the first conductor (130).

2. The high-voltage cable (100) according to claim 1, wherein the heat pipe (110) is arranged such that the adiabatic zone (ZA) is at least partly outside the first conductor (130).

3. The high-voltage cable (100) according to claim 1 or 2, wherein the high-voltage cable (100) is configured such that in use the condensation zone (Zc) is arranged at a higher vertical elevation than the evaporation zone (ZE).

4. The high-voltage cable (100) according to any one of the preceding claims, wherein the high- voltage cable (100) comprises:- a first end (100') configured to be connected to a battery (200); and- a second end (100"), opposite the first end (100'), configured to be connected to a charging port (300) or a charging cable connector.

5. The high-voltage cable (100) according to claim 4, wherein the evaporation zone (ZE) is arranged to absorb thermal energy from the first end (100') and / or the second end (100") of the high-voltage cable (100).

6. The high-voltage cable (100) according to claim 4 or 5, wherein the heat pipe (110) extends out of the first conductor (130) at the first end (100') or the second end (100") of the high-voltage cable (100).

7. The high-voltage cable (100) according to any one of claims 4 - 6, wherein the high-voltage cable (100) comprises:- a second heat pipe (110) comprising an evaporation zone (ZE), an adiabatic zone (ZA), and a condensation zone (Zc), wherein the condensing zone (Zc) is arranged outside the first conductor (130), and the evaporation zone (ZE) is arranged inside the first conductor (130), wherein the evaporation zone (ZE) of the first heat pipe (110) is arranged to absorb thermal energy from the first end (100') of the conductor (130) and the evaporation zone (ZE) of the second heat pipe (100) is arranged to absorb thermal energy from the second end (100') of the conductor (130).

8. The high-voltage cable (100) according to any one of the preceding claims, wherein the high- voltage cable (100) comprises:- a second conductor (160), wherein the second conductor (160) is an extruded hollow profile with an outer surface and an inner surface; and- a third electrically insulating layer (170) applied on the outer surface of the second conductor (160).

9. The high-voltage cable (100) according to claim 8, wherein the first conductor (130) is arranged coaxially inside the second conductor (160).

10. An electric vehicle (1), wherein the electric vehicle (1) comprises:- a high-voltage cable (100) according to any one of the preceding claims;- a battery (200); and- a charging port (300); wherein the high-voltage cable (100) at a first end (100') is connected to the battery (200) and at a second end (100") is connected to the charging port (300).

11. The electric vehicle (1) according to claim 10, wherein the electric vehicle (1) comprises:- a cooling system (400) for cooling of the condensation zone (Zc) of the heat pipe (110).

12. A method for manufacturing a high-voltage cable (100), wherein the high-voltage cable (100) is a cable according to any one of claims 1-9, wherein the method comprises the steps of:- providing a first conductor (130) by means of extruding a hollow profile comprising a hollow chamber extending through a longitudinal direction of the first conductor (130);- providing a heat pipe (110) comprising an evaporation zone (Zf), an adiabatic zone (ZA), and a condensation zone (Zc), wherein the evaporation zone (Zf) has a diameter which is smaller than an inner diameter of the hollow chamber;- applying a first electrically insulating layer (120) onto an outer surface of the heat pipe (110) and / or an inner surface of the hollow chamber; and- assembling the first conductor (130) and the heat pipe (110) by placing the evaporation zone (Zf) of the heat pipe (110) inside the hollow chamber and crimping the first conductor (130) or expanding the heat pipe (110) to provide a tight fit between the heat pipe (110) and the first conductor (130).

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