Superconducting electric machine

Abstract

The superconducting electrical machine (20) comprises a rotor (22) and a stator casing (21) comprising at least one first vacuum enclosure (23) configured to house a first superconducting coil (30) and at least one first cooling enclosure (24), configured to house a first stator polyphase winding (40), the first cooling enclosure being intended to contain a cooling fluid. At least one wall (27) of the first vacuum enclosure forms a wall (37) of the first cooling enclosure. Figure for abstract: Fig 2

Description

Title of the invention: Superconducting electric machine Technical field

[0001] The invention relates to superconducting electrical machines, and more particularly to a stator casing for such machines.

[0002] The invention further relates to an aircraft comprising such a superconducting electrical machine. Previous techniques

[0003] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are being or will be adopted by various states. In particular, an ambitious standard applies both to new types of aircraft and those in circulation requiring the implementation of technological solutions in order to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0004] Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental consequences with the aim of improving the energy efficiency of aircraft.

[0005] Consequently, the Applicant is constantly working to reduce its negative climate impact by using methods and operating virtuous development and manufacturing processes and minimizing greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0006] This sustained research and development work covers new generations of aircraft engines, the lightening of aircraft, in particular through the materials used and lighter on-board equipment, the development of the use of electrical technologies to ensure propulsion, and, as essential complements to technological progress, aeronautical biofuels.

[0007] Propulsion systems for electric or hybrid aircraft require the use of electric machines capable of competing with, or even exceeding, the performance of turbomachines.

[0008] Electric machines intended for the propulsion of electric aircraft must deliver significant specific powers. For this purpose, there is a so-called superconducting material which, when cooled below a certain specific critical temperature (also known as the "superconductivity temperature"), loses all electrical resistance. In other words, it allows an electric current to flow through it without any energy loss due to zero electrical resistance.

[0009] This critical temperature is generally less than 100 Kelvin and makes it possible to circulate large currents without loss of energy.

[0010] It is then proposed to use superconducting materials in the production of electrical machines intended to be mounted in the propulsion system. More particularly, when electrical machine coils are made of superconducting materials, they can carry high direct current densities without energy loss and thus generate very high magnetic fields.

[0011] Such coils can be used to create inductors of electrical machines in order to obtain a large and controllable magnetic field in the machine without requiring rotating contact systems. In order to transform this continuous field into a variable field in the space necessary for the production of torque, this type of machine employs a rotor whose objective is to deflect, guide or trap this magnetic field using ferromagnetic or superconducting materials.

[0012] [Fig. 1] illustrates a partial longitudinal section of an example of an axial flux superconducting electric machine 1.

[0013] The electrical machine 1 comprises a stator casing 2 comprising an annular vacuum enclosure 3 housing an annular coil 4 made of a superconducting material, a first annular housing 5 comprising a first polyphase annular stator winding 6, a second annular housing 7 comprising a second polyphase annular stator winding 8 and a rotor 9.

[0014] The annular vacuum enclosure 3 surrounds the annular housings 5, 7.

[0015] The rotor 9 comprises regularly arranged superconducting pellets 10 according to a diameter of the rotor 9 extending in a radial plane of the rotor 9 between the first and second polyphase windings 6, 8 and radially inside the superconducting coil 4.

[0016] The annular vacuum enclosure 3 makes it possible to maintain the superconducting coil 4 at a sufficiently low temperature so that the coil 4 retains its superconducting properties. In other words, the temperature of the coil 4 is maintained at a temperature below the superconductivity temperature.

[0017] Generally, the annular vacuum enclosure 3 is made of aluminum.

[0018] The variable field generated by the rotor 9 generates eddy currents which induce thermal losses in the vacuum enclosure 3.

[0019] The heat losses heat the walls of the vacuum enclosure 3 so that the temperature of the walls of the vacuum enclosure 3 may exceed the maximum permissible temperature of the materials consisting of the elements in contact with said walls. More specifically, these materials are designed with mechanical, electrical or chemical characteristics that operate within a given temperature range. This temperature range is generally determined based on the expected properties of the material. However, if the temperature to which these materials are exposed increases beyond this range, the materials may no longer meet the expected standards and performances. Furthermore, when these materials are subjected to these excessive temperatures, several problems may arise such as undesirable dimensional changes of said elements or a degradation of their chemical properties.

[0020] It is then suggested to use cooling as a solution to maintain the temperature of the materials within acceptable limits. Thus, in the field of electrical machines, it is proposed to cool the vacuum enclosure 3 to maintain the stability or the properties of the materials making up said elements.

[0021] For this purpose, the electrical machine 1 comprises a first cooling system for cooling the vacuum enclosure 3 comprising, for example, cooling channels 11 arranged outside the vacuum enclosure 3 for cooling said enclosure 3.

[0022] A cooling fluid circulates inside said channels 11.

[0023] Furthermore, the polyphase windings 6, 8 supplied by a current generate losses by Joules effect.

[0024] To improve the performance of the electrical machine 1, the electrical machine 1 generally comprises a second cooling system for cooling the first and second polyphase windings 6, 8 making it possible to inject into said windings an electric current of greater amplitude.

[0025] The second cooling system comprises the annular housings 5, 7 and cooling fluid supply means supplying the housings 5, 7 with cooling fluid.

[0026] The machine 1 thus comprises two independent cooling systems, complicating the production of the stator casing 2.

[0027] Indeed, each cooling system requires hydraulic connections to be supplied with cooling fluid. It is also necessary for the cooling systems to be watertight by implementing, for example, seals which require grooves to be made to accommodate them.

[0028] Furthermore, the size of the annular housings 5, 7 prevents the cooling channels 11 of the vacuum enclosure 3 from being positioned as close as possible to the heat losses. generated above the 10 pellets. Statement of the invention

[0029] The aim of the invention is to overcome all or part of these drawbacks.

[0030] To this end, the invention is the result of technological research aimed at very significantly improving the performance of aircraft and, in this sense, contributes to reducing the environmental impact of aircraft. For this purpose, the invention relates to a superconducting electrical machine comprising a rotor and a stator casing comprising at least a first vacuum enclosure configured to house a first superconducting coil and at least a first cooling enclosure configured to house a first polyphase stator winding, the first cooling enclosure being intended to contain a cooling fluid.

[0031] At least one wall of the first vacuum enclosure forms a wall of the first cooling enclosure.

[0032] The use of one of the walls of the first vacuum enclosure to produce one of the walls of each cooling enclosure makes it possible to simplify the design of the stator casing by reducing the number of elements constituting the stator casing and eliminating the cooling channels for cooling the first vacuum enclosure known from the state of the art.

[0033] The mass of the stator casing is reduced, facilitating, for example, the integration of the electric machine into the propulsion system of the aircraft.

[0034] The stator housing has a single cooling system for cooling the first vacuum enclosure and the cooling enclosure allowing for the reduction of hydraulic connections and sealing elements.

[0035] Furthermore, since the cooling channels of the first vacuum enclosure have been eliminated, the radial distance between the support element and the first vacuum enclosure is reduced compared to a machine known from the state of the art allowing better cooling of the second circular wall of the first vacuum enclosure located above the support element which concentrates most of the heat losses.

[0036] The cooling of the first vacuum enclosure is improved, allowing a significant reduction in the temperature rise of the vacuum enclosure, for example up to 70% compared to the cooling of the vacuum enclosure of a machine known from the state of the art.

[0037] Preferably, the superconducting electrical machine comprises a second cooling enclosure configured to house a second polyphase stator winding, the first cooling enclosure forming a first chamber annular cooling chamber and the second cooling enclosure forming a second annular cooling chamber, the first annular cooling chamber comprising a first annular wall, the second annular cooling chamber comprising a second annular wall, the first annular wall of the first annular cooling chamber being parallel and facing the second annular wall of the second annular cooling chamber, the first annular wall of the first annular cooling chamber being separated from the second annular wall of the second annular cooling chamber by a predetermined distance so that the rotor of the electric machine is inserted between the first annular wall of the first annular cooling chamber and the second annular wall of the second annular cooling chamber,the first vacuum enclosure forming an annular vacuum chamber which comprises an inner circular wall and an outer circular wall of the first and second annular cooling chambers.

[0038] Advantageously, the first cooling enclosure forms an annular cooling chamber configured to further house a second polyphase stator winding, the first vacuum enclosure forming an annular vacuum chamber, an inner circular wall and an outer circular wall of the annular cooling chamber, the annular cooling chamber further comprising an annular recess comprising a first annular wall extending in a radial direction of the electric machine, and comprising a second annular wall extending in a radial direction of the electric machine, the second annular wall being opposite the first annular wall, the first annular wall and the second annular wall being configured to house the rotor of the electric machine.

[0039] Preferably, the first superconducting coil is housed in the annular vacuum chamber, and the rotor is superconducting and comprises superconducting pellets regularly arranged along a diameter of the rotor in a radial plane of the rotor between the first and second annular walls and radially inside the first superconducting coil.

[0040] Advantageously, the rotor comprises a ferromagnetic mass arranged between the first and second annular walls.

[0041] Preferably, the superconducting electrical machine comprises a second cooling enclosure configured to house a second polyphase stator winding, the first cooling enclosure forming a first annular cooling chamber, the second enclosure forming a second annular cooling chamber and the first vacuum enclosure forming an annular vacuum chamber, the annular vacuum chamber being interposed between the first annular cooling chamber and the second annular cooling chamber in an axial direction of the electric machine, at least a first wall of the annular vacuum chamber forming at least a first wall of the first annular cooling chamber and at least a second wall of the annular vacuum chamber forming at least a first wall of the second annular cooling chamber.

[0042] Advantageously, the first superconducting coil is housed in the annular vacuum chamber, and a first polyphase stator winding is housed in the first annular cooling chamber, the superconducting electrical machine comprising a second polyphase stator winding housed in the second annular cooling chamber, the rotor being homopolar and inserted in the first annular cooling chamber, the second annular cooling chamber and the annular vacuum chamber so that the first polyphase stator winding includes a first ferromagnetic mass of the rotor and so that the second polyphase stator winding includes a second ferromagnetic mass of the rotor.

[0043] Preferably, the superconducting electrical machine comprises a second vacuum enclosure configured to house a second superconducting coil, the first cooling enclosure forming an annular cooling chamber, the first vacuum enclosure forming a first annular vacuum chamber and the second vacuum enclosure forming a second annular vacuum chamber, the annular cooling chamber being interposed between the first annular vacuum chamber and the second annular vacuum chamber in an axial direction of the electrical machine, the wall of the first vacuum enclosure forming the wall of the first cooling enclosure and a wall of the second vacuum enclosure forming at least one other wall of the first cooling enclosure.

[0044] Advantageously, the first polyphase stator winding is housed in the annular cooling chamber, the first superconducting coil is housed in the first annular vacuum chamber, the superconducting electrical machine comprising a second superconducting coil housed in the second annular vacuum chamber, the rotor being superconducting and comprising superconducting plates arranged on the surface of the rotor, the superconducting plates being encompassed by the first polyphase stator winding.

[0045] An aircraft comprising a superconducting electrical machine as defined above is also proposed. Brief description of the drawings

[0046] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example and made with reference to the appended drawings in which:

[0047] - Figure [Fig. 1] illustrates an example of an axial flux electric machine known from the state of the art,

[0048] - figure [Fig.2] illustrates a first example of a superconducting electric machine- axial flux duct according to the invention,

[0049] - figure [Fig.3] illustrates a second example of a superconducting electric machine- axial flux duct according to the invention,

[0050] - figure [Fig.4] illustrates a first example of a superconducting electric machine- radial flux duct according to the invention,

[0051] - Figure [Fig.5] illustrates a second example of a superconducting electric machine- radial flux duct according to the invention, and

[0052] - figure [Fig.6] illustrates an example of an aircraft according to the invention. Detailed description

[0053] Reference is made to [Fig.2] which illustrates a partial longitudinal section of a first example of an axial flux superconducting electric machine 20.

[0054] The machine 20 comprises a stator casing 21 and a rotor 22.

[0055] The rotor 22 rotates along a longitudinal axis A of the machine 20.

[0056] The stator casing 21 comprises a first vacuum enclosure forming a annular vacuum chamber 23, a first cooling enclosure forming a first annular cooling chamber 24 and a second cooling enclosure forming a second annular cooling chamber 25.

[0057] A central axis of the annular vacuum chamber 23, of the first annular cooling chamber 24 and of the second annular cooling chamber 25 is coaxial with the longitudinal axis A of the machine 20.

[0058] The annular vacuum chamber 23 is for example made of aluminum.

[0059] The annular vacuum chamber 23 comprises a first circular wall 26 external, a second internal circular wall 27, a first annular wall 28 and a second annular wall 29 parallel to the first annular wall 28.

[0060] The first annular wall 28 and the second annular wall 29 connect the first circular wall 26 and the second circular wall 27.

[0061] The annular vacuum chamber 23 houses a first annular superconducting coil 30.

[0062] The first superconducting coil 30 is made of a superconducting material, for example Niobium Tin, Nb3Sn, or Niobium Titanium, NbTi in magnesium diboride MgB2, in REBaCuO or in BiSrCaCuO.

[0063] The first annular cooling chamber 24 comprises a first wall 31 extending in a radial direction of the stator casing 21 and the second annular cooling chamber 25 comprises a second annular wall 32 extending in a radial direction of the stator casing 21.

[0064] The first annular cooling chamber 24 comprises a third annular wall 33 facing and parallel to the first annular wall 31, an internal circular wall 35 and an external circular wall 37.

[0065] The second annular cooling chamber 25 comprises a fourth annular wall 34 facing and parallel to the second annular wall 32, an internal circular wall 36 and an external circular wall 38.

[0066] The inner circular wall 35 of the first annular cooling chamber 24 and the outer circular wall 37 of the first annular cooling chamber 24 connect the first wall 31 and the third annular wall 33.

[0067] The inner circular wall 36 of the second annular cooling chamber 25 and the outer circular wall 38 of the second annular cooling chamber 25 connect the second wall 32 and the fourth annular wall 34.

[0068] The first wall 31 is parallel and opposite the second wall 32, said walls being separated by a predetermined distance D.

[0069] The first annular cooling chamber 24 comprises a first annular polyphase winding 40 arranged in said chamber on the first wall 31 and the second annular cooling chamber 25 comprises a second annular polyphase winding 41 arranged in said chamber on the second wall 32.

[0070] The first and second polyphase windings 40, 41 are opposite each other.

[0071] As shown, the first wall 31, the third wall 33 and the internal circular wall 35 can be produced by a primary element 42 comprising a crown 42a in a radial direction of the stator and a cylindrical surface 42b having a central axis coaxial with the axis A, and a secondary element 44 comprising a crown 44a in a radial direction of the stator and a cylindrical surface 44b having a central axis coaxial with the axis A.

[0072] Similarly, the second wall 32, the fourth wall 34 and the internal circular wall 36 can be produced by a primary element 43 comprising a crown 43a in a radial direction of the stator and a cylindrical surface 43b having a central axis coaxial with the axis A, and a secondary element 45 comprising a crown 45a in a radial direction of the stator and a cylindrical surface 45b having a central axis coaxial with the axis A.

[0073] The crown 42a of the primary element 42 of the first annular cooling chamber 24 forms the first wall 31 of the first annular cooling chamber 24, the crown 44a of the secondary element 44 of the first chamber annular cooling chamber 24 forms the third wall 33 of the first annular cooling chamber 24, and the cylindrical surfaces 42b, 44b of the primary element 42 and the secondary element 44 of the first annular cooling chamber 24 form the inner circular wall 35 of the first annular cooling chamber 24.

[0074] To ensure sealing between the cylindrical surfaces 42b and the cylindrical surfaces 44b, the cylindrical surface 42b of the primary element 42 comprises a groove 42c in which a seal 42d is inserted, coming into contact with the cylindrical surface 44b of the secondary element 44.

[0075] Alternatively, the cylindrical surface 44b of the secondary element 44 comprises the groove and the seal.

[0076] Similarly, the crown 43a of the primary element 43 of the second annular cooling chamber 25 forms the second wall 32 of the second annular chamber 25, the crown 45a of the secondary element 45 of the second annular cooling chamber 25 forms the fourth wall 34 of the second annular cooling chamber 25, and the cylindrical surfaces 43b, 45b of the primary element 43 and of the secondary element 45 of the second annular cooling chamber 25 form the internal circular wall 36 of the second annular cooling chamber 25.

[0077] The cylindrical surfaces 43b, 45b are superimposed on each other.

[0078] To ensure sealing between the cylindrical surface 43b and the cylindrical surface 45b, the cylindrical surfaces 43b of the primary element 43 comprise a groove 43c in which is inserted a seal 43d coming into contact with the cylindrical surface 45b of the secondary element 45.

[0079] Alternatively, the cylindrical surface 45b of the secondary element 45 comprises the groove and the seal.

[0080] The external circular walls 37, 38 of the first and second cooling enclosures are formed by the second circular wall 27 of the first vacuum enclosure 23.

[0081] To ensure sealing between the vacuum enclosure and the first and second cooling enclosures, the surface of the crown 42a, 43a, 44a, 45a of the elements 42, 43, 44, 45 in contact with the first vacuum enclosure 23 comprises a seal 46 housed in a groove 47 of the crown so that the seal 46 comes into contact with the second circular wall 27 of the first vacuum enclosure 23.

[0082] The cooling enclosures are connected to supply means (not shown) for cooling fluid.

[0083] The cooling fluid is for example oil.

[0084] The supply means are capable of delivering the cooling fluid into each cooling enclosure for cooling the annular polyphase winding of said enclosure and the vacuum enclosure.

[0085] The rotor 22 comprises a rotor shaft 22a and a circular support element 22b inserted between the first and second annular walls 31, 32.

[0086] The distance D is chosen as a function of the thickness of the support element so that an air gap remains between a first face of the support element and the first wall 31 of the first annular cooling chamber 24, and an air gap remains between a second face of the support element opposite the first face and the second wall 32 of the second annular cooling chamber 25 allowing the rotation of the support element between the first and second walls 31, 32.

[0087] The radial distance between the support element and the first vacuum enclosure is chosen so that a space remains between the support element and said enclosure.

[0088] The support element 22b comprises superconducting pellets 48 arranged regularly along a diameter of the rotor 22 in a radial plane of the rotor 22 between the first and second walls 31, 32 and radially inside the superconducting coil 30, the rotor 22 forming a superconducting rotor.

[0089] Alternatively, the superconducting pellets 48 of the support element 22b are replaced by ferromagnetic elements.

[0090] The use of one of the walls of the first vacuum enclosure to produce one of the walls of each cooling enclosure makes it possible to simplify the design of the stator casing 21 by reducing the number of elements constituting the stator casing and eliminating the cooling channels for cooling the first vacuum enclosure known from the state of the art.

[0091] The mass of the stator casing 21 is reduced, facilitating, for example, the integration of the machine 20 into an aircraft.

[0092] The stator housing 21 comprises a single cooling system for cooling the first vacuum chamber and the cooling chambers allowing the reduction of hydraulic connections and sealing elements.

[0093] Furthermore, as the cooling channels of the first vacuum enclosure have been removed, the radial distance between the support element and the first vacuum enclosure is reduced compared to a machine known from the state of the art allowing better cooling of the second circular wall 27 of the first vacuum enclosure located above the support element 22b which concentrates the majority of the thermal losses.

[0094] The cooling of the first vacuum enclosure is improved, allowing a significant reduction in the temperature rise of the vacuum enclosure, for example up to 70% compared to the cooling of the vacuum enclosure of a machine. known from the state of the art.

[0095] [Fig.3] illustrates a partial longitudinal section of a second example of the axial flux superconducting electric machine 20.

[0096] The machine 20 comprises a stator casing 50 and the rotor 22.

[0097] The stator casing 50 comprises the first vacuum enclosure forming the annular vacuum chamber 23 and the first cooling enclosure forming an annular cooling chamber 51.

[0098] The annular vacuum chamber 23 houses the first annular superconducting coil 30.

[0099] A central axis of the annular vacuum chamber 23 and of the annular cooling chamber 51 is coaxial with the longitudinal axis A of the machine 20.

[0100] The annular cooling chamber 51 comprises an annular recess 52 opening into the interior of the central space of the annular cooling chamber 51.

[0101] The recess 52 comprises a first annular wall 53 extending in a radial direction of the stator casing 51, a second annular wall 54 facing and parallel to the first wall 53 and a circular wall 55 connecting the first and second walls 53, 54.

[0102] The recess 52 houses the support element 22b of the rotor 22.

[0103] The distance DI between the first wall 53 and the second wall 54 of the recess 52 is chosen as a function of the thickness of the support element so that an air gap remains between a first face of the support element and the first wall 53 of the recess 52, and an air gap remains between a second face of the support element opposite the first face and the second wall 35 of the recess 52.

[0104] The radial distance D2 between the support element 22b and the circular wall 55 is chosen so that sufficient clearance separates the support element 22b and the circular wall 55 to allow rotation of the support element 22b in the recess 52.

[0105] The annular cooling chamber 51 further comprises a third annular wall 56 extending in a radial direction of the stator casing 50, a fourth annular wall 57 extending in a radial direction of the stator casing 50, an internal circular wall 58 located inside the central space of the annular cooling chamber 51 and an external circular wall 59 opposite the internal circular wall 58.

[0106] The recess 52 is arranged between the third and fourth walls 56, 57 connected by the external circular wall 59.

[0107] The inner circular wall 58 is connected to the third and fourth walls 56, 57 and includes the opening of the recess 52.

[0108] The annular cooling chamber 51 comprises a first winding polyphase 60 annular winding arranged in said chamber on the first wall 53 and a second polyphase 61 annular winding arranged in said chamber on the second wall 54.

[0109] The first and second polyphase windings 60, 61 are opposite each other.

[0110] As shown, the first wall 53, the second wall 54, the circular wall 55 of the recess, the third wall 56, the fourth wall 57 and the internal circular wall 58 can be made by two secondary elements 44, 45 as described previously, a tertiary element 62 and a quaternary element 63.

[0111] The tertiary element 62 comprises a crown 62a, extending in a radial direction of the stator, a first cylindrical surface 62b inside the central space of the crown 62a and having a central axis coaxial with the axis A, and a second cylindrical surface 62c on the periphery of the crown 62a and having a central axis coaxial with the axis A.

[0112] The quaternary element 63 comprises a crown 63a, extending in a radial direction of the stator, and a cylindrical surface 63b inside the central space of the crown 63a and having a central axis coaxial with the axis A.

[0113] The crown 62a of the tertiary element 62 forms the first wall 53, the crown 63a of the quaternary element 63 forms the second wall 54, the second cylindrical surface 62c and the crown 63a of the quaternary element 63 form the circular wall 55 of the recess 52.

[0114] The crown 44a of a first secondary element 44 forms the third wall 56 and the crown 45a of the second secondary element 45 forms the fourth wall 57.

[0115] The cylindrical surface 44b of the first secondary element 44, the first cylindrical surface 62b of the tertiary element 62, the cylindrical surface 45b of the second secondary element 45 and the first cylindrical surface 63b of the quaternary element 63 form the internal circular wall 58.

[0116] The cylindrical surfaces 62b, 44b are superimposed on each other, and the cylindrical surfaces 63b, 45b are superimposed on each other.

[0117] To ensure sealing between the superimposed cylindrical surfaces 62b, 44b, the cylindrical surface 62b of the tertiary element 62 comprises a groove 62d in which a seal 62e is inserted, coming into contact with the cylindrical surface 44b of the first secondary element 44.

[0118] Alternatively, the cylindrical surface 44b of the first secondary element 44 comprises the groove and the seal.

[0119] To ensure sealing between the superimposed cylindrical surfaces 63b, 45b, the cylindrical surface 63b of the quaternary element 63 comprises a groove 63c in which a seal 63d is inserted coming into contact with the cylindrical surface 44b of the second secondary element 45.

[0120] Alternatively, the cylindrical surface 45b of the second secondary element 45 comprises the groove and the seal.

[0121] To ensure sealing between the second cylindrical surface 62c of the tertiary element 62 and the crown 63a of the quaternary element 63, the second cylindrical surface 62c of the tertiary element 62 comprises a groove 62f in which a seal 62ge is inserted coming into contact with the crown 63a of the quaternary element 63.

[0122] Alternatively, the crown 63a the quaternary element 63 comprises the groove and the seal.

[0123] The external circular wall 59 of the cooling enclosure is formed by the second circular wall 27 of the first vacuum enclosure 23.

[0124] As described previously, to ensure sealing between the vacuum enclosure and the cooling enclosure, the surface of the crown 44a, 45a of the secondary elements 44, 45 in contact with the vacuum enclosure comprises a seal 46 housed in a groove 47 of the crown so that the seal 46 comes into contact with the second circular wall 27 of the first vacuum enclosure 23.

[0125] The cooling enclosure is connected to the cooling fluid supply means.

[0126] Unlike the first example of embodiment of the machine illustrated in [Fig.2], the stator casing comprises a single cooling enclosure further simplifying the production of said stator by reducing the hydraulic connections as well as the number of sealing elements comprising the grooves and the seals.

[0127] This second example of the machine is not suitable for a machine comprising a single annular polyphase winding.

[0128] [Fig.4] illustrates a partial longitudinal section of a first example of a radial flux superconducting electric machine 70.

[0129] The machine 70 comprises a stator casing 71 and a homopolar rotor 72 comprising two ferromagnetic masses 72a, 72b.

[0130] Each ferromagnetic mass 72a, 72b comprises poles.

[0131] The rotor 72 rotates along a longitudinal axis B of the machine 70.

[0132] The stator casing 71 comprises a first vacuum enclosure forming a annular vacuum chamber 73, a first cooling enclosure forming a first annular cooling chamber 74 and a second cooling enclosure forming a second annular cooling chamber 75.

[0133] A central axis of the annular vacuum chamber 73, the first annular cooling chamber 74 and the second annular cooling chamber 75 is coaxial with the longitudinal axis B of the machine 70.

[0134] The annular vacuum chamber 73 is for example made of aluminum.

[0135] The annular vacuum chamber 73 comprises a first circular wall 26 external, a second internal circular wall 27 in the central space of the chamber annular vacuum wall 73, a first annular wall 78 and a second annular wall 79 parallel to the first wall 78.

[0136] The first wall 78 and the second wall 79 connect the first circular wall 76 and the second circular wall 77.

[0137] The annular vacuum chamber 73 houses a first annular superconducting coil 80.

[0138] The first superconducting coil 80 is made of a superconducting material, for example Niobium Tin, Nb3Sn, Niobium Titanium, NbTi, magnesium diboride MgB2, REBaCuO or BiSrCaCuO.

[0139] Each annular cooling chamber 74, 75 comprises a first annular wall 81, 82 extending in a radial direction of the stator casing 71, a second annular wall 83, 84 facing and parallel to the first wall 81, 82, an internal circular wall 85, 86 arranged in the central opening of said annular chamber 74, 75, and an external circular wall 87, 88.

[0140] The inner circular walls 85, 86 and outer 87, 88 connect the first wall 81, 82 and the second wall 83, 84 to each other.

[0141] The annular vacuum chamber 73 is interposed between the first annular cooling chamber 74 and the second annular cooling chamber 75 in an axial direction of the electric machine 70.

[0142] The first annular cooling chamber 74 comprises a first annular polyphase winding 89 disposed in said chamber on the inner circular wall 85, and the second annular cooling chamber 75 comprises a second annular polyphase winding 90 disposed in said chamber on the inner circular wall 86.

[0143] The rotor 72 is inserted into the first annular cooling chamber 74, the second annular cooling chamber 75 and the annular vacuum chamber 73 such that a first ferromagnetic mass 72a of the rotor 72 is encompassed by the first polyphase winding 89 and the second ferromagnetic mass 72b of the rotor 72 is encompassed by the second polyphase winding 90.

[0144] As shown, for each annular cooling chamber 74, 75, the second wall 83, 84, the internal circular wall 85, 86 and the external circular wall 87, 88 may be produced by an annular element 91, 92 comprising a crown 91a, 92a extending in a radial direction of the stator, a first cylindrical surface 91b, 92b having a central axis coaxial with the axis B and located in the central space of said annular cooling chamber, and a second cylindrical surface 91c, 92c having a central axis coaxial with the axis B.

[0145] The crown 91a of the element 91 of the first annular cooling chamber 74 forms the second wall 83 of the first annular cooling chamber. dissement 74, the first crown 91b of the element 91 of the first annular cooling chamber 74 forms the inner circular wall 85 of the first annular cooling chamber 74, and the second cylindrical surface 91c of the element 91 of the first annular cooling chamber 74 forms the outer circular wall 87 of the first annular cooling chamber 74.

[0146] Similarly, the crown 92a of the element 92 of the second annular cooling chamber 75 forms the second wall 84 of the second annular cooling chamber 75, the first crown 92b of the element 92 of the second annular cooling chamber 75 forms the inner circular wall 86 of the second annular cooling chamber 75, and the second cylindrical surface 92c of the element 92 of the second annular cooling chamber 75 forms the outer circular wall 88 of the second annular cooling chamber 75.

[0147] The first wall 81 of the first annular cooling chamber 74 is formed by the first wall 78 of the annular vacuum chamber 73, and the first wall 82 of the second annular cooling chamber 75 is formed by the second wall 79 of the annular vacuum chamber 73.

[0148] To ensure sealing between the first and second cylindrical surfaces 91b, 91c of the first annular cooling chamber 74 and the first wall 78 of the annular vacuum chamber 73, the ends of the first and second cylindrical surfaces 91b, 91c in contact with the first wall 78 of the annular vacuum chamber 73 comprise a groove 93 in which a seal 94 is inserted coming into contact with the first wall 78 of the annular vacuum chamber 73.

[0149] Alternatively, the first wall 78 of the annular vacuum chamber 73 comprises the grooves and the seals.

[0150] To ensure sealing between the first and second cylindrical surfaces 92b, 92c of the second annular cooling chamber 75 and the second wall 79 of the annular vacuum chamber 73, the ends of the first and second cylindrical surfaces 92b, 92c in contact with the second wall 79 of the annular vacuum chamber 73 comprise the groove 93 in which the seal 94 coming into contact with the second wall 79 of the annular vacuum chamber 73 is inserted.

[0151] Alternatively, the second wall 79 of the annular vacuum chamber 73 comprises the grooves and the seals.

[0152] The cooling enclosures 74, 75 are connected to the cooling fluid supply means.

[0153] [Fig.5] illustrates a partial longitudinal section of a second example of the radial flux superconducting electric machine 70.

[0154] The machine 70 comprises a stator casing 100 and a rotor 101.

[0155] The rotor 101 rotates along a longitudinal axis C of the machine 70, and comprises a cylindrical support element 101a and superconducting plates 101b arranged on the surface of the rotor, the rotor being a superconducting rotor.

[0156] The stator housing 100 comprises a first vacuum enclosure forming a first annular vacuum chamber 102, a second vacuum enclosure forming a second annular vacuum chamber 103 and a first cooling enclosure forming an annular cooling chamber 104.

[0157] The annular cooling chamber is interposed between the first annular vacuum chamber and the second annular vacuum chamber in an axial direction of the electric machine 70.

[0158] A central axis of the first annular vacuum chamber 102, the second annular vacuum chamber 103 and the annular cooling chamber 104 is coaxial with the longitudinal axis C of the machine 70.

[0159] The annular vacuum chambers 102, 103 are for example made of aluminum.

[0160] Each annular vacuum chamber 102, 103 comprises a first external circular wall 105, 106, a second internal circular wall 107, 108 in the central space of said annular vacuum chamber, a first annular wall 109, 110 and a second annular wall 111, 112 parallel to the first wall 109, 110.

[0161] The first annular wall 109, 110 and the second wall 111, 112 connect the first circular wall 105, 106 and the second circular wall 107, 108.

[0162] The first annular vacuum chamber 102 houses a first annular superconducting coil 113 and the second annular vacuum chamber 103 houses a second annular superconducting coil 114.

[0163] The superconducting coils 113, 114 are made of a superconducting material, for example Niobium Tin, Nb3Sn, or Niobium Titanium, NbTi, magnesium diboride MgB2, REBaCuO or BiSrCaCuO.

[0164] The annular chamber 104 comprises an inner circular wall 115 disposed in the central opening of the annular chamber 104, an outer circular wall 116, a first wall 117 and a second wall 118.

[0165] The inner circular walls 115 and outer circular walls 116 are connected to each other by the first wall 117 and the second wall 118.

[0166] The annular cooling chamber 104 comprises a first annular polyphase winding 119 arranged in said chamber on the internal circular wall 115.

[0167] The rotor 101 is inserted into the annular vacuum chambers 102, 103 and the annular cooling chamber 104 so that the superconducting plates 101b are encompassed by the first polyphase winding 119.

[0168] As shown, the annular cooling chamber 104 is for example made from a first cylindrical element 120 and a second cylindrical element 121 comprising a cylindrical surface 121a having a central axis coaxial with the axis C

[0169] The first cylindrical element 120 comprises a cylindrical surface 120a having a central axis coaxial with the axis C, a first annular element 120b extending in a radial direction of the stator and located at a first end of the cylindrical surface 120a, and a second annular element 120c parallel to the first annular element 120b and located at a second end of the cylindrical surface 120a.

[0170] The cylindrical surface 121a of the second cylindrical element 121 forms the inner circular wall 115 and the cylindrical surface 120a of the first cylindrical element 120 forms the outer circular wall 116.

[0171] The first wall 117 is formed by the first annular element 120b of the first cylindrical element 120, the first circular wall 105 and the first annular wall 109 of the first annular vacuum chamber 102.

[0172] The second wall 118 is formed by the second annular element 120c of the first cylindrical element 120, the first circular wall 106 and the first annular wall 110 of the second annular vacuum chamber 103.

[0173] The first cooling enclosure is connected to the cooling fluid supply means.

[0174] [Fig.6] illustrates an example of an aircraft 130 comprising two superconducting machines 70 arranged on either side of a longitudinal axis of the aircraft 130, the aircraft being an airplane.

[0175] Each machine 70 is connected to a propulsion propeller 131.

[0176] Alternatively, the aircraft may comprise a helicopter comprising the superconducting machine 70 driving propulsion blades of the helicopter.

Claims

1.

2.

3. Claims Superconducting electrical machine (20, 70) comprising a rotor (22) and a stator casing (21, 50, 71, 100) comprising at least one first vacuum enclosure (23, 73, 111) configured to house a first superconducting coil (30, 80, 113) and at least one first cooling enclosure (24, 51, 74, 104), configured to house a first polyphase stator winding (40, 60, 89, 119), the first cooling enclosure being intended to contain a cooling fluid, the superconducting electrical machine (20, 70) being characterized in that at least one wall (27, 78, 105, 109) of the first vacuum enclosure (23, 73, 111) forms a wall (37, 59, 81, 117) of the first cooling enclosure (24, 51, 74, 104). Superconducting electrical machine (20) according to claim 1, comprising a second cooling enclosure configured to house a second polyphase stator winding (41), the first cooling enclosure (24, 51, 74, 104) forming a first annular cooling chamber (24) and the second cooling enclosure forming a second annular cooling chamber (25), the first annular cooling chamber (24) comprising a first annular wall (31), the second annular cooling chamber (25) comprising a second annular wall (32), the first annular wall (31) of the first annular cooling chamber (24) being parallel and facing the second annular wall (32) of the second annular cooling chamber (25),the first annular wall (31) of the first annular cooling chamber (24) being separated from the second annular wall (32) of the second annular cooling chamber (25) by a predetermined distance (D) so that the rotor (22) of the electric machine fits between the first annular wall (31) of the first annular cooling chamber (24) and the second annular wall (32) of the second annular cooling chamber (25), the first vacuum enclosure (23, 73, 111) forming an annular vacuum chamber (23) which comprises an internal circular wall (27) and an external circular wall (37, 38) of the first and second annular cooling chambers (24, 25)., A superconducting electrical machine (20) according to claim 1, wherein the first cooling enclosure (24, 51, 74, 104) forms an annular cooling chamber (23) configured to further house a second polyphase stator winding (61), the first vacuum enclosure forming an annular vacuum chamber (23), an inner circular wall (27) and an outer circular wall (59) of the annular cooling chamber (23), the annular cooling chamber (23) further comprising an annular recess (52) comprising a first annular wall (53) extending in a radial direction of the electric machine, and comprising a second annular wall (54) extending in a radial direction of the electric machine, the second annular wall (54) being opposite the first annular wall (53), the first annular wall (53) and the second annular wall (54) being configured to house the rotor (22) of the electric machine (20).

4. A superconducting electrical machine (20) according to claim 2 or 3, wherein the first superconducting coil (30) is housed in the annular vacuum chamber (23), and wherein the rotor (22) is superconducting and comprises superconducting pellets (48) regularly arranged along a diameter of the rotor (22) in a radial plane of the rotor (22) between the first and second annular walls (31, 32, 53, 54) and radially inside the first superconducting coil (30).

5. A superconducting electrical machine (20) according to claim 2 or 3, wherein the rotor (22) comprises a ferromagnetic mass disposed between the first and second annular walls (31, 32, 53, 54).

6. A superconducting electrical machine (70) according to claim 1, comprising a second cooling enclosure configured to house a second polyphase stator winding (90), the first cooling enclosure forming a first annular cooling chamber (74), the second enclosure forming a second annular cooling chamber (75) and the first vacuum enclosure forming an annular vacuum chamber (73), the annular vacuum chamber (73) being interposed between the first annular cooling chamber (74) and the second annular cooling chamber (75) in an axial direction of the electrical machine, at least a first wall (78) of the annular vacuum chamber forming at least a first wall of the first annular cooling chamber (74) and at least a second wall (79) of the

7.

8.

9. annular vacuum chamber forming at least a first wall of the second annular cooling chamber (75). The superconducting electrical machine (70) of claim 6, wherein the first superconducting coil (80) is housed in the annular vacuum chamber (73), wherein a first polyphase stator winding (89) is housed in the first annular cooling chamber (74), the superconducting electrical machine (70) having a second polyphase stator winding (90) housed in the second annular cooling chamber (75), the rotor (20) being homopolar (72) and inserted into the first annular cooling chamber, the second annular cooling chamber and the annular vacuum chamber such that the first polyphase stator winding (89) includes a first ferromagnetic mass (72a) of the rotor (20) and such that the second polyphase stator winding (90) includes a second ferromagnetic mass (72b) of the rotor (20).The superconducting electrical machine (70) of claim 1, comprising a second vacuum enclosure configured to house a second superconducting coil (114), the first cooling enclosure forming an annular cooling chamber (104), the first vacuum enclosure forming a first annular vacuum chamber (102) and the second vacuum enclosure forming a second annular vacuum chamber (103), the annular cooling chamber (104) being interposed between the first annular vacuum chamber (102) and the second annular vacuum chamber (103) in an axial direction of the electrical machine, the wall (105, 109) of the first vacuum enclosure forming the wall (117) of the first cooling enclosure and a wall (106, 110) of the second vacuum enclosure forming at least one other wall (118) of the first cooling enclosure. The superconducting electric machine (70) of claim 8, wherein the first polyphase stator winding (119) is housed in the annular cooling chamber (104), wherein the first superconducting coil (113) is housed in the first annular vacuum chamber (102), the superconducting electric machine (70) comprising a second superconducting coil (114) housed in the second annular vacuum chamber (103), the rotor (20) being superconducting (101) and comprising superconducting plates (101b) arranged on the surface of the rotor (20), the superconducting plates (101b) being encompassed by the first polyphase stator winding (119).

10. An aircraft (130) comprising a superconducting electrical machine (20, 70) according to any one of claims 1 to 9.

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