SUPERCONDUCTING CABLE COMPRISING A SUPERCONDUCTING FUSE ZONE AND AIRCRAFT COMPRISING SUCH A SUPERCONDUCTING CABLE

Abstract

Superconducting cable comprising a superconducting fuse zone and aircraft comprising such a superconducting cable. The invention relates to a superconducting cable (10) comprising a superconducting element (12) and a superconducting fuse zone (14) arranged on a predefined section (L) of the superconducting element, said superconducting fuse zone comprising a heating element (30) configured to regulate the temperature of the superconducting element in the superconducting fuse zone. Advantageously, such a superconducting fuse has a better ratio between its current breaking capacity on the one hand and its volume and weight on the other hand. Fig. 1

Description

Title of the invention: SUPERCONDUCTING CABLE COMPRISING A SUPERCONDUCTING FUSE ZONE AND AIRCRAFT COMPRISING SUCH A SUPERCONDUCTING CABLE Technical field

[0001] The present application relates to a superconducting cable comprising a superconducting element and a superconducting fusible zone of this superconducting element, in particular for a power electronics circuit of an electrically powered aircraft. STATE OF THE PRIOR ART

[0002] Liquid hydrogen is a cryogenic fluid that can be used as an energy source for the production of electricity. Thus, for example, it is possible to use a hydrogen fuel cell to power all of an aircraft's flight control and communication systems, as well as on-board lighting and the power supply of several accessory devices used in the aircraft. Liquid hydrogen can also be used as an energy source for aircraft propulsion, by powering a fuel cell or by direct combustion, which has the advantage of releasing only water into the atmosphere. The use of hydrogen requires distribution systems between one or more production or storage tanks and consuming devices.Thus, pipes are conventionally used to transport liquid hydrogen between a storage tank and a liquid hydrogen consuming device, such as a hydrogen fuel cell.

[0003] There is a need to massively reduce the production of carbon dioxide emissions to preserve the environment, and electric or hybrid propulsion proves promising in this regard. But conventional systems on board an aircraft are such that the mass / electric power ratio is not satisfactory as it stands and there is therefore a need to obtain electrical systems capable of providing power according to their weight to satisfy all constraints. This is the case for electrical fuses as well as other electrical components of aircraft.

[0004] It is therefore necessary to optimize the electrical power / weight ratio of all the elements of the propulsion system of an aircraft, and in particular of the power components crossed by strong currents and which must have a breaking capacity of high current.

[0005] The situation can therefore be improved. Summary of the invention

[0006] The present invention relates to a fuse function of a superconducting cable having a capacity to break said superconducting cable compatible with the electric current requirements of an electrically powered aircraft, while having weight and dimensional characteristics compatible with the constraints of aeronautics.

[0007] To this end, the invention relates to a superconducting cable for supplying electrical energy to an aircraft electric propulsion motor, comprising a superconducting element extending longitudinally between first and second ends, as well as a superconducting fusible zone arranged on a predefined section between the first and second ends of the superconducting element, said superconducting fusible zone comprising a heating element configured to regulate the temperature of the superconducting element in the superconducting fusible zone.

[0008] According to one feature, the heating element is a metal cable connected to a source of electric current, said source of electric current being configured to control the electric current flowing in said heating element.

[0009] According to one characteristic, the superconducting element takes the form of a superconducting strip or a superconducting ribbon.

[0010] According to one characteristic, the superconducting element comprises, in the superconducting fusible zone, impurities inserted into said superconducting element.

[0011] According to one characteristic, the impurities are fragments of aluminum or copper.

[0012] According to one characteristic, the superconducting element comprises, in the superconducting fusible zone, a local reduction in the cross-section of the superconducting element.

[0013] According to one characteristic, the superconducting element comprises, in the superconducting fusible zone, a curvature in the cross-section of the superconducting element.

[0014] According to one feature, the superconducting cable also comprises a first chamber containing a cryogenic fluid and a second vacuum chamber, the superconducting element and the heating element being arranged in the first chamber, the first chamber being surrounded by the second chamber.

[0015] According to one characteristic, the source of electric current is arranged outside the second chamber.

[0016] According to one feature, the cable also comprises a first vacuum chamber and cooling means arranged partly in the first chamber, the superconducting element and the heating element being arranged in the first chamber, the cooling means being configured to cool the superconducting element by conduction.

[0017] According to one characteristic, the cooling means comprise a conductive element and a cooling source arranged to cool the conductive element, the conductive element being arranged in the first chamber in contact with the superconductive element.

[0018] According to one characteristic, the conductive element is made of copper.

[0019] The invention also relates to an aircraft comprising a superconducting cable according to the invention. Brief description of the drawings

[0020] The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of at least one embodiment, said description being made in relation to the appended drawings among which:

[0021] [Fig.l] schematically represents a superconducting cable comprising a fusible zone according to a first embodiment of the invention;

[0022] [Fig.2] schematically represents a superconducting cable comprising a zone fuse according to a second embodiment of the invention;

[0023] [Fig.3] schematically represents a superconducting cable comprising a zone fuse according to a third embodiment of the invention;

[0024] [Fig.4] schematically represents a superconducting cable comprising a zone fuse according to a fourth embodiment of the invention;

[0025] [Fig.5] schematically represents an aircraft comprising at least one supra cable conductor comprising a fusible zone according to one of [Fig.l], [Fig.2], [Fig.3] or [Fig.4];

[0026] [Fig.6] schematically represents a superconducting cable comprising a zone fuse according to another embodiment of the invention;

[0027] [Fig.7] schematically represents a superconducting cable comprising a zone fuse according to another embodiment of the invention; and

[0028] [Fig.8] schematically represents a superconducting cable comprising a zone fuse according to another embodiment of the invention.

[0029] DETAILED DESCRIPTION OF AN EMBODIMENT

[0030] [Fig.l] represents a superconducting cable 10 comprising a superconducting element 12 extending longitudinally in a longitudinal direction X between first and second ends, as well as a superconducting fusible zone 14 (or superconducting fuse) according to a first embodiment of the invention.

[0031] The superconducting element 12 is configured to transmit an electric current between its first and second ends. The superconducting element 12 may be a superconducting ribbon, a superconducting tape, or a superconducting wire.

[0032] The superconducting cable 10 is thus arranged between a first element 20 of the electrical energy source type and a second element 22 of the electrical load type, the superconducting cable 10, and more precisely the superconducting element 12, having a function of superconducting electrical power supply link of the electrical load from the electrical energy source. For example, the first end 12a of the superconducting element 12 is electrically connected to an electrical energy source 20 and the second end 12b of the superconducting element 12 is electrically connected to an electrical load 22, such as an aircraft electric propulsion motor.

[0033] The superconducting element 12 is made of a superconducting material, even in the superconducting fusible zone 14. In a non-limiting manner and by way of example, the superconducting element 12 can be made of tin, aluminum, lead, zinc or even titanium.

[0034] The superconducting fusible zone 14 extends over a predefined section of the superconducting cable 10, and therefore over a section L of predetermined length between the first and second ends of the superconducting element 12. For example, the section L represents less than 20% of the length of the superconducting element 12, in particular less than 10% of the length of the superconducting element 12, preferably less than 1% of the length of the superconducting element 12.

[0035] The superconducting fusible zone 14 is configured to define an electric current for breaking the superconducting element 12, i.e. an electric current that the superconducting element 12 can withstand transmitting without deterioration, and the electric current from which the superconducting element 12 will break and interrupt the transmission of the electric current. The superconducting fusible zone 14 therefore makes it possible to predefine an electric current for melting the section of the superconducting element 12 in said superconducting fusible zone 14, i.e. an electric current which, when present for a predetermined time, causes the melting of the superconducting element 12, at least in the superconducting fusible zone 14.The superconducting fusible zone 14 is thus called “rupture initiation zone” or “breakdown initiation zone”, this superconducting fusible zone 14 representing a portion of the superconducting element 12 which is more fragile (or weak) with respect to an overcurrent (an overcurrent) circulating through the superconducting element 12.

[0036] As with conventional fuses, the precise characteristics of the fusible zone superconducting element 14 are not detailed here and are considered to be defined by laboratory tests and calibrations or by feedback, before the manufacture of the superconducting cable 10, depending on the electric currents not to be transmitted, the surrounding conditions, the material used for the superconducting element 12...

[0037] Thus, in the present description, it is considered that the superconducting fusible zone 14 is configured to open the electrical circuit when a current Imax flows through it for a predetermined duration Tl. The corresponding characteristics Imax and Tl are further determined for each of the circuits or circuit branches of an aircraft which must be able to be electrically isolated from the other circuits in the event of a fault occurring in this circuit or circuit branch.

[0038] According to a first embodiment, the superconducting fusible zone 14 comprises a heating element 30. The heating element 30 is arranged in the fusible zone 14, close to the superconducting element 12, and configured to control the temperature of the fusible zone 14. The superconducting fusible zone 14 has a predefined fusion current value associated therewith. The heating element 30 is configured to, when necessary, cause the superconducting fusible zone 14 to reach this predefined fusion current value (the heating element acting on the temperature of the superconducting fusible zone 14, which is intrinsically linked to the value of the electric current flowing in said superconducting fusible zone 14). The heating element 30 may be a loop of a metal wire connected to an electric current source 32, which is itself configured to control the electric current flowing through the heating element 30.The electric current source 32 is configured to allow a small amount of electric current to pass through the heating element 30 so that the heating element 30 can generate heat. The heating element 30 is configured to regulate the electric current flowing in the superconducting element 12, at the superconducting fusible zone 14, that is to say on the section of the superconducting element 12 corresponding to the superconducting fusible zone 14. The heating element 30 is configured to regulate the electric current flowing in the superconducting element 12, locally in the superconducting fusible zone 14, so as to create a localized “quench”.

[0039] Superconducting elements have a parameter called critical current, which is defined as the electric current at which superconducting elements lose their superconductivity (i.e., a “quench” phenomenon appears in the superconducting elements). This “quench” phenomenon is thus defined as an unexpected transition from the superconducting state of the superconducting element to the conventional state. The current flowing through a superconducting element is proportional to the temperature of said superconducting element. By adding a heating element 30 in the breakdown initiation zone (superconducting fuse zone 14) of the superconducting element, the heating element 30 can be used to generate a thermal current. conductor, it is possible to limit the critical / quench current in this breakdown initiation zone. Since the critical current is temperature dependent, by regulating the temperature of the heating element 30, it is possible to regulate the critical current in the superconducting element 12.

[0040] When a fault occurs in the aircraft's electrical propulsion system, the energy source (here fuel cells or batteries) continues to supply said fault, risking damaging components or causing a fire. According to the invention, the use of a rupture initiation zone which can be extinguished (i.e. which can lose its superconductivity) thus makes it possible to draw all the energy from the energy source instead of injecting it into said fault. Indeed, the “quench” phenomenon is caused by faults or short circuits in the aircraft's electrical propulsion system.

[0041] With a superconducting fuse according to the invention, it is possible to regulate the current at which the “quench” phenomenon will occur, thus creating different levels of protection for takeoff, cruise flight and landing of the aircraft, for which there are different operating currents.

[0042] In order to maintain the superconducting state of the superconducting cable 10, the superconducting element 12 is arranged in a first chamber 50 filled with a cryogenic fluid 52, such as liquid or gaseous dihydrogen (H2). In order to thermally isolate the first chamber 50 from an influence of an external temperature, a second chamber 54, placed under vacuum, surrounds the first chamber 50.

[0043] The heating element 30 is arranged in the first chamber 50, and the electric current source 32 supplying said heating element 30 is arranged outside the second chamber 54.

[0044] According to one configuration, the vacuum in the second chamber 54 is obtained during the manufacture of the superconducting cable. According to an alternative configuration, the vacuum in the second chamber 54 is obtained before energizing the electrical circuit(s) concerned by the superconducting fuse 14, by means of dedicated equipment such as a vacuum pump.

[0045] According to one configuration, the superconducting cable 10 is a cryogenic cable also comprising the first chamber 50 arranged around the superconducting conductor 12 and the second chamber 54, under vacuum, surrounding said first chamber 50. Such a configuration simplifies the manufacturing and assembly operations by limiting the number of connection points between the superconducting fuse and cryogenic power conductors, which also makes it possible to reduce the weight of the assembly.

[0046] Furthermore, since the superconducting fuse 14 is cooled in the same manner as the conductive element 12 of the cryogenic superconducting cable 10, the resistance continuous (direct current) of the superconducting fuse 14 is almost zero. As a result, the efficiency gain is very high compared to a conventional fuse since the power loss in the superconducting fuse 14 is very low.

[0047] In addition, the insulation provided by the second vacuum chamber 54 makes it possible to control the generation of a possible electric arc after a fault has occurred and the superconducting fuse 14 has broken. Thus, no additional system or material is required to dampen the effects of the generated electric arc.

[0048] According to one configuration, the first chamber 50 containing the cryogenic fluid 52 is connected to a cryogenic fluid supply system of the aircraft, at an opening.

[0049] According to a configuration shown in [Fig.6], the superconducting cable 10 has a dedicated source of cryogenic fluid 60, such as a cryo-cooler, connected to the opening of the first chamber 50.

[0050] Fuse rating requirements vary widely for different aircraft systems, and it may be useful to have an adjustable value for the melting current of a given fuse. In one configuration, the melting current of the superconducting fuse 14 is also controlled by controlling the temperature of the cryogenic fluid 52 present in the first chamber 50. For this purpose, the aircraft cryogenic fluid supply system, or the dedicated cryogenic fluid source 60, is connected to a cryogenic fluid temperature control module 62 (shown in [Fig. 6]).

[0051] According to a configuration shown in [Fig.7], the melting current of the superconducting fuse 14 is also controlled by placing a magnetic field source 70 (connected to an alternating current generator 70) in or near the superconducting fuse zone 14. The magnetic field generated in the superconducting fuse zone 14 then makes it possible to adjust the melting current of said superconducting fuse. This is particularly advantageous for the branches of the main circuit of an aircraft, knowing for example that the total current necessary for the takeoff of the aircraft can be up to three times the nominal current consumed by the same aircraft in cruising flight.

[0052] It is thus advantageously possible to modulate the melting current of a fuse of a specific branch of an aircraft circuit as a function of the different flight phases such as, for example, takeoff, cruising flight, landing or an emergency situation.

[0053] According to a second embodiment shown in [Fig.2], the superconducting element 12 comprises, in the section L corresponding to the superconducting fusible zone 14, impurities 40 inserted into the superconducting element 12. The impurities are for example fragments of copper or aluminum.

[0054] According to a third embodiment shown in [Fig. 3], the superconducting element 12 has, in the section L corresponding to the superconducting fusible zone 14, a local reduction 42 of the cross-section (i.e. a calibrated narrowing) of the superconducting element 12.

[0055] According to a fourth embodiment shown in [Fig.4], the superconducting element 12 has a curvature 44 in the cross-section (i.e. a calibrated fold) in the superconducting element 12.

[0056] Any of these different embodiments in which the break initiation zone is obtained by adding a heating element 30, and further by adding, in the superconducting fusible zone 14, impurities 40 in the superconducting element 12, or by local reduction 42 of the section of the superconducting element 12 or by at least one calibrated curvature 44 in the superconducting element 12, may comprise additional means for controlling and adjusting the fusion current or the fusion time by adjusting the temperature of the cryogenic fluid, a magnetic field in the break initiation zone, or both.

[0057] [Fig. 5] represents an aircraft 1 which comprises at least one superconducting cable 10 as described previously, implemented either as a stand-alone component or as part of a cryogenic power circuit such as for example a cryogenic superconducting cable.

[0058] [Fig. 8] shows an embodiment of the cryogenic superconducting cable 10 in which the superconducting element 12 is cooled by conduction. As mentioned previously, the superconducting element 12 is arranged in a first chamber 80, said first chamber 80 being placed under vacuum, instead of being filled with a cryogenic fluid. The heating element 30 is also arranged in the first chamber 80 which is placed under vacuum. The superconducting element 12 is cooled by conduction, for example by contact with a cooled conductive element 82. The conductive element 82 may be made of copper, and is, for example, a copper connection. The conductive element 82 is cooled with a cooling source 84 and forms with the cooling source 84 cooling means 86. The cooling source 84 may be at cryogenic temperature.The cooling source 84 is thus arranged to cool the conductive element 82, while the conductive element 82 is arranged in contact with the superconducting element 12 to cool the superconducting element 12. The conductive element 82 is thus placed in the first evacuated chamber 80. The cooling source 86 can be arranged in the first evacuated chamber 80, or outside the first chamber 80 (configuration shown in [Fig. 8]). The cooling means 86 can thus be arranged at least partially in the first chamber 80 and cool the superconducting element 12 by conduction.

Claims

Claims

1. Superconducting cable (10) for supplying electrical energy to an aircraft electric propulsion motor, comprising a superconducting element (12) extending longitudinally between first and second ends (12a, 12b), as well as a superconducting fusible zone (14) arranged on a predefined section (L) between the first and second ends (12a, 12b) of the superconducting element (12), said superconducting fusible zone (14) comprising a heating element (30) configured to regulate the temperature of the superconducting element (12) in the superconducting fusible zone (14).

2. The superconducting cable (10) of claim 1, wherein the heating element (30) is a metal cable connected to an electric current source (32), said electric current source (32) being configured to control the electric current flowing through said heating element (30).

3. Superconducting cable (10) according to one of claims 1 or 2, wherein the superconducting element (12) comprises, in the superconducting fusible zone (14), impurities (40) inserted into said superconducting element (12).

4. Superconducting cable (10) according to one of claims 1 to 3, wherein the superconducting element (12) comprises, in the superconducting fusible zone (14), a local reduction (42) of the cross-section of the superconducting element (12).

5. Superconducting cable (10) according to one of claims 1 to 4, wherein the superconducting element (12) comprises, in the superconducting fusible zone (14), a curvature (44) in the cross-section of the superconducting element (12).

6. Superconducting cable (10) according to one of claims 1 to 5, also comprising a first chamber (50) containing a cryogenic fluid (52) and a second chamber (54) under vacuum, the superconducting element (12) and the heating element (30) being arranged in the first chamber (50), the first chamber (50) being surrounded by the second chamber (54).

7. A superconducting cable (10) according to claim 6, dependent on claim 2, wherein the electric current source (32) is arranged outside the second chamber (54).

8. Superconducting cable (10) according to one of claims 1 to 5, also comprising a first vacuum chamber (50) and cooling means (86) arranged partly in the first chamber (50), the superconducting element (12) and the heating element (30) being arranged in the first chamber (50), the cooling means (86) being configured to cool the superconducting element (12) by conduction.

9. A superconducting cable (10) according to claim 8, wherein the cooling means (86) comprises a conductive element (82) and a cooling source (84) arranged to cool the conductive element (82), the conductive element (82) being arranged in the first chamber (50) in contact with the superconductive element (12).

10. Aircraft (1) comprising a superconducting cable (10) according to one of claims 1 to 9.

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