SUPERCONDUCTING MOTOR WITH COOLING SYSTEM

Abstract

SUPERCONDUCTING MOTOR WITH COOLING SYSTEM The invention relates to a superconducting motor (100) comprising a rotor (102), a stator (112) outside the rotor (102) and traversed by an even number of holes (116), for each pair of holes (116), a coil (120) comprising a U-shaped base (202) and U-shaped sheets (204) and made of a superconducting material, where the sheets (204) are fixed to each other and to the base (202), where each column of a coil (120) is inserted into one of the holes (116) of the pair of holes (116). With such an arrangement, the manufacture of the coils and their installation are simplified. Fig. 1

Description

Title of the invention: SUPERCONDUCTING MOTOR COMPRISING A COOLING SYSTEM Technical field

[0001] The present invention relates to the general field of superconducting motors and more particularly to superconducting motors comprising a cooling system. STATE OF THE PRIOR ART

[0002] [Fig.5] shows a superconducting motor 300 of the state of the art, where the superconducting motor 300 is seen in section through a plane perpendicular to the longitudinal axis X of said superconducting motor 300.

[0003] The superconducting motor 300 comprises a rotor 302 which has a rotor core 304 made of a ferromagnetic material such as all iron alloys used for electrical machines. The rotor core 304 is cylindrical and coaxial with the longitudinal axis X and it has a central bore 306 in which a motor shaft 308 of said superconducting motor 300 is fitted and rigidly fixed. The motor shaft 308 is coaxial with the longitudinal axis X.

[0004] The rotor 302 also comprises permanent magnets 310 fixed to the rotor core 304 on the periphery of the latter. There are several permanent magnets 310 (here six in number) distributed angularly and regularly around the rotor core 304 and spaced from one another. Conventionally, the permanent magnets 310 are magnetized radially relative to the longitudinal axis X and in an alternating manner from one to the other.

[0005] The superconducting motor 300 comprises a stator 312 arranged outside the rotor 302 and comprises a stator core 314 made of a ferromagnetic material such as all iron alloys used for electrical machines. The stator core 314 takes a generally cylindrical shape coaxial with the longitudinal axis X.

[0006] At its cylindrical face which is oriented towards the rotor 302, the stator core 314 has slots 316 which here open towards the rotor 302. There are several slots 316 (here sixteen in number) distributed angularly and regularly around the rotor 302. The successive slots 316 are separated by a tooth 318 which is a single piece and made of a single material with the stator core 314. The slots 316 are arranged in pairs. A pair of slots 316 is formed of two non-successive slots 316. In particular, the slots 316 of a pair of slots 316 are separated by two slots 316 belonging to different pairs of slots 316.

[0007] For each pair of slots 316, the stator 312 comprises a coil 320. A coil 320 is wound in a pair of slots 316, around a plurality of teeth 318. Each coil 320 is made of a ribbon of superconducting material. In particular, the ribbon of superconducting material is wound radially to the longitudinal axis X in the slots 316 so as to form a coil 320. The coil 320 thus forms a stack of a superconducting ribbon in each slot 316. The superconducting ribbons are arranged perpendicular to the magnetic field lines which are inside the slots 316. Two slots 316 associated with the same coil 320 are separated by two slots 316 associated with two other coils 320. The coils 316 are thus intertwined with each other in the slots 316.

[0008] The rotor 302 and the stator 312 are conventionally housed in a motor housing 322 which is cylindrical and closed at its two ends by sides, at least one of which is pierced with a central orifice allowing the passage of the motor shaft 308. The stator 312 is mounted fixed inside the motor housing 322 while the rotor 302 and the motor shaft 308 are mounted free to rotate inside the motor housing 322.

[0009] In operation, each coil 320 is electrically powered to generate a magnetic field that interacts with the permanent magnets 310 to drive them into rotation with the rotor 302 and the motor shaft 308.

[0010] The superconducting motor 300 comprises an inner cylinder 324 and an outer cylinder 326 which are coaxial with the longitudinal axis X.

[0011] The inner cylinder 324 is disposed between the rotor 302 and the stator 312, and the outer cylinder 326 is disposed around the stator 312 and inside the motor housing 322.

[0012] The inner cylinder 324 and the outer cylinder 326 extend between the two flanks to which they are hermetically fixed to delimit between them and the two flanks, a chamber 328 in which the stator 312 is housed and which can be evacuated.

[0013] In the context of a superconducting motor 300, the coils 320 must be cooled to improve their efficiency. To this end, for each slot 316, tubes 330 are arranged in the bottom of the slot 316 between the coil 320 housed in the slot 316 and the stator core 314. These tubes 330 are fluidically connected to a source of a refrigerant fluid. The refrigerant fluid is then injected into the tubes 330 to cool the coils 320.

[0014] Although such an arrangement gives good results, it is desirable to find a new arrangement which simplifies the process of manufacturing the coils and the implantation of these coils in the superconducting motor. Statement of the invention

[0015] An object of the present invention is to provide a superconducting motor comprising:

[0016] - a rotor with a rotor core carrying permanent magnets and movable in rotation around a longitudinal axis,

[0017] - a stator arranged outside the rotor and comprising a stator core made in a ferromagnetic material and crossed by an even number of orifices distributed angularly and regularly around the rotor,

[0018] - for each pair of orifices, a coil comprising:

[0019] - a U-shaped base with two first columns and a first bottom fixed between the two first columns, and

[0020] - a plurality of sheets, each taking the shape of a U with two second columns and a second bottom and being made of a superconducting material, where the sheets are fixed on top of each other so as to form a stack and where said stack is fixed on the base by aligning each first column with second columns of the sheets and the first bottom with the second bottoms of the sheets,

[0021] where each column of a coil is inserted into one of the holes of the pair of holes.

[0022] With such an arrangement, the manufacture of the reels and their installation are simplified since it is no longer necessary to wind a ribbon.

[0023] Advantageously, the base is pierced with a channel with two openings, where one opening opens at the end of each first column, where the openings are intended to be fluidically connected to a refrigerant circuit.

[0024] Advantageously, the orifices associated with the same coil are separated by two orifices associated with two other coils.

[0025] The present invention also relates to an aircraft comprising at least one superconducting engine according to the invention.

[0026] Advantageously, the aircraft comprises a refrigerant circuit comprising a source of refrigerant fluid, said source of refrigerant fluid being fluidically connected to the openings of the channel of the base of the coil, said channel being configured to be crossed by the refrigerant fluid between said openings.

[0027] The present invention also relates to a method of manufacturing a coil, comprising:

[0028] - a step of producing by additive manufacturing a U-shaped base with two first columns and a first background fixed between the first two columns,

[0029] - a step of providing a plurality of sheets made of a supra material driver,

[0030] - a step of stacking said plurality of sheets,

[0031] - a step of cutting said stack of sheets so as to give said leaves a U shape with two second columns forming the legs of the U and a second bottom fixed between the two second columns, and

[0032] - a step of fixing said stack of sheets on said base by aligning each first column with second columns of leaves and the first background with the second backgrounds of leaves.

[0033] Advantageously, the method comprises, prior to the step of cutting the stack of sheets, a step of fixing the sheets of the stack to each other.

[0034] Advantageously, the method comprises, after the step of cutting the stack of sheets, a step of fixing the sheets of the U-shaped stack to each other. Brief description of the drawings

[0035] The above-mentioned features of the invention, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, said description being made in relation to the attached drawings, among which:

[0036] [Fig-1] is a sectional view of a superconducting motor according to the invention,

[0037] [Fig.2] is a perspective view of a coil implemented in the supra motor driver according to the invention,

[0038] [Fig.3] is a sectional view along curve III-III of [Fig. 1],

[0039] [Fig.4] is a curve showing the AC losses in the case of the invention and a state of the art, and

[0040] [Fig.5] is a sectional view of a state-of-the-art superconducting motor.

[0041] DETAILED DESCRIPTION OF EMBODIMENTS

[0042] [Fig.l] shows a superconducting motor 100 according to the invention in section through a plane perpendicular to the longitudinal axis X of the superconducting motor 100 and [Fig.3] shows a section at the level of arc III-III. The superconducting motor 100 has generally the same structure as the superconducting motor 300 of the state of the art.

[0043] The superconducting motor 100 comprises a rotor 102 which is rotatable about the longitudinal axis X and which has a rotor core 104 made of a ferromagnetic material such as all iron alloys used for electrical machines. The rotor core 104 is cylindrical and coaxial with the longitudinal axis X and it has a central bore 106 in which a motor shaft 108 of said superconducting motor 100 is fitted and rigidly fixed. The motor shaft 108 is coaxial with the longitudinal axis X.

[0044] The rotor 102 also comprises permanent magnets 110 fixed to the rotor core 104 on the periphery of the latter. There are several permanent magnets 110 (here six in number) distributed angularly and regularly around the rotor core 104 and spaced apart from each other. Conventionally, the permanent magnets 110 are magnetized radially relative to the longitudinal axis X and alternately north-south from near to near.

[0045] The superconducting motor 100 comprises a stator 112 arranged outside the rotor 102 and comprising a cylindrical stator core 114 coaxial with the longitudinal axis X.

[0046] The stator core 114 is made of a ferromagnetic material such as all iron alloys used for electrical machines.

[0047] The stator core 114 is crossed by an even number of orifices 116 (here sixteen in number) distributed angularly and regularly around the rotor 102. Two successive orifices 116 are separated by a tooth 118 in one piece and in one material with the stator core 114. The orifices 116 are here closed opposite the rotor 102, but each orifice 116 can take the form of a slot as in the state of the art.

[0048] For each pair of orifices 116, the superconducting motor 100 comprises a coil 120.

[0049] [Fig.2] shows an example of a coil 120 according to the invention.

[0050] The coil 120 has a base 202 which takes the shape of a U with two first columns 202a forming the legs of the U and a first base 202b fixed between the two first columns 202a, here at one end of each first column 202a and forming the base of the U.

[0051] The coil 120 also comprises a plurality of sheets 204, each taking the shape of a U with two second columns 204a forming the legs of the U and a second bottom 204b fixed between the two second columns 204a, here at one end of each second column 204a and forming the bottom of the U.

[0052] Each sheet 204 is made of a superconducting material such as all iron alloys used for electrical machines.

[0053] The sheets 204 are fixed, for example glued, on top of each other so as to form a stack 206 which also takes the shape of a U by superimposing the second columns 204a on top of each other and the second bottoms 204b on top of each other.

[0054] The stack 206 is fixed, for example glued, on the base 202 by aligning each first column 202a with one of the two stacks of the second columns 204a of the sheets 204 and the first bottom 202b with the stack of the second bottoms 204b of the sheets 204.

[0055] The coil 120 thus takes the general shape of a U with two columns and a bottom connecting the two columns. The two columns are each made up of the stack of a first column 202a and the second columns 204a and the bottom is made up of the stack of the first bottom 202b and the second bottoms 204b.

[0056] Each column 202a, 204a of a coil 120 is inserted into one of the holes 116 of the pair of holes 116 while the bottom 202b, 204b of the coil 120 remains outside as shown in [Fig.3]. The columns 202a, 204a are parallel to the longitudinal axis X.

[0057] The manufacture of the coil 120 by assembling sheets 204 on a base 202 is therefore simple to carry out and the installation and replacement of the coil 120 is also simple to carry out because it is sufficient to slide the columns 202a, 204a into the orifices 116.

[0058] With such an arrangement, the sheets 204 are arranged parallel to the magnetic field lines that are inside the orifices 116. Such an arrangement further allows for a reduction in losses compared to sheets that would be placed radially. [Fig. 4] shows the evolution of the AC losses of the motor for the invention (curve 402) and for a motor with sheets installed radially (curve 404). In [Fig. 4], the abscissa axis represents the time in ms and the ordinate axis represents the losses in W.

[0059] In the embodiment of the invention presented here, the rotor 102 and the stator 112 are housed in a motor housing 122 which is cylindrical and closed at its two ends by sides, at least one of which is pierced with a central orifice allowing the passage of the motor shaft 108. The stator 112 is mounted fixed inside the motor housing 122 while the rotor 102 and the motor shaft 108 are mounted free to rotate inside the motor housing 122.

[0060] In operation, each coil 120 is electrically powered by an alternating current to generate a magnetic field which interacts with the permanent magnets 110 to drive them in rotation with the rotor 102 and the motor shaft 108. For each coil 120, the electrical power supply is provided from the free ends of the second columns 204b, i.e. at the ends located opposite the second bottoms 204b. The free ends of the second columns 204b of one of the two stacks are thus electrically connected to a terminal of an electrical converter and the free ends of the second columns 204b of the other of the two stacks are thus electrically connected to another terminal of an electrical converter.

[0061] As with the prior art superconducting motor 300, the superconducting motor 100, in the embodiment of the invention presented here, comprises an inner cylinder 124 and an outer cylinder 126 which are coaxial with the longitudinal axis X.

[0062] The inner cylinder 124 is disposed between the rotor 102 and the stator 112 and the outer cylinder 126 is disposed around the stator 112 and inside the motor housing 122.

[0063] The inner cylinder 124 and the outer cylinder 126 extend between the two flanks to which they are hermetically fixed to delimit between them (the two inner cylinders 124 and outer 126) and the two sides, a chamber 128 in which the stator 112 is housed and which can be evacuated.

[0064] To ensure the cooling of the sheets 204, the base 202 is pierced with a channel 208 with two openings 208a-b. One opening 208a-b opens at the free end of a first column 202a and the other opening 208b-a opens at the free end of the other first column 202a and the channel 208 thus extends in the base 202 in the first columns 202a and in the bottom 204a.

[0065] The openings 208a-b are fluidically connected to a refrigerant circuit which ensures the circulation of a refrigerant fluid in the channel 208 by entering through one opening 208a-b and exiting through the other opening 208b-a. The arrows F of [Fig.3] show the direction of movement of the refrigerant fluid. The refrigerant circuit comprises for example a reservoir for the refrigerant fluid and a pump for circulating the refrigerant fluid.

[0066] The base 202 functions as a heat exchanger between the refrigerant fluid and the sheets 204. The base 202 is made of a material having good thermal conductivity such as a copper alloy for example, so as to ensure correct heat transfer while reducing the induced losses associated with pure metals.

[0067] As shown in [Fig.3], the two orifices 116 associated with the same coil 120 are separated by two orifices 116 associated with two other coils 120, but they could be just neighbors.

[0068] The configuration shown in [Fig.3] with the two orifices 116 associated with the same coil 120 separated by two orifices 116 associated with two other coils 120 allows a greater electro-mechanical conversion (i.e. allows more mechanical power to be obtained) with the same quantity of electrical current at input, compared to a configuration where the orifices 116 associated with a coil 120 would be neighbors.

[0069] The superconducting engine 100 is integrated into an aircraft comprising a refrigerant circuit with a source of refrigerant fluid which is fluidically connected to the openings 208a-b of the channel 208 of the base 202 of the coil 120. In particular, the channel 208 is configured to be crossed by the refrigerant fluid between said openings 208a-b.

[0070] The method of manufacturing such a coil 120 will now be described.

[0071] The method comprises, from a plurality of sheets 204 of superconducting material, a step E10 of stacking said plurality of sheets 204, one on top of the other.

[0072] The method also comprises, after step E10, a cutting step E20 said stack of sheets 204 so as to give the sheets 204 a U shape, with two second columns 204a forming the legs of the U and a second bottom 204b fixed between the two second columns 204a, here at one end of each second column 204a and forming the bottom of the U.

[0073] The method comprises upstream, in parallel, or after steps E10 and E20, a step E30 of producing the base 202 by additive manufacturing. The U-shaped base 202 with the first two columns 202a and the first bottom 202b fixed between the first two columns 202a is produced by additive manufacturing (also known by the acronym ALM for “Additive Layer Manufacturing” in English).

[0074] The method comprises, after steps E20 and E30, a step E40 of fixing the stack of the plurality of U-shaped sheets 204 on the U-shaped base 202, so as to obtain the coil 120 by aligning each first column 202a of the base 202 with second columns 204a of the sheets 204 and the first bottom 202b of the base 202 with the second bottoms 204b of the sheets 204. In particular, the stack of the plurality of sheets 204 can be glued to the base 202.

[0075] According to one embodiment, during a step E11, after step E10 and before step E20, the sheets 204 of this stack can be fixed, that is to say joined, secured, for example glued, to each other.

[0076] According to one embodiment, during a step E21, after step E20 and before step E30, the U-shaped sheets 204 of this stack can be fixed, i.e. secured, joined, for example glued, to each other.

[0077] The coil 120 thus obtained is then integrated into the rotor 102 of the superconducting motor 100.

Claims

Claims

1. Superconducting motor (100) comprising: - a rotor (102) with a rotor core (104) carrying permanent magnets (110) and rotatable about a longitudinal axis (X), - a stator (112) arranged outside the rotor (102) and comprising a stator core (114) made of a ferromagnetic material and crossed by an even number of orifices (116) distributed angularly and regularly around the rotor (102), - for each pair of orifices (116), a coil (120) comprising: - a U-shaped base (202) with two first columns (202a) and a first bottom (202b) fixed between the two first columns (202a), and - a plurality of sheets (204), each taking the shape of a U with two second columns (204a) and a second bottom (204b) and being made of a material superconductor,wherein the sheets (204) are fixed on top of each other so as to form a stack (206) and wherein said stack (206) is fixed on the base (202) by aligning each first column (202a) with second columns (204a) of the sheets (204) and the first bottom (202b) with the second bottoms (204b) of the sheets (204), wherein each column (202a, 204a) of a coil (120) is inserted into one of the holes (116) of the pair of holes (116).,

2. Superconducting motor (100) according to claim 1, characterized in that the base (202) is pierced with a channel (208) with two openings (208a-b), where one opening (208a-b) opens at the end of each first column (202a), where the openings (208a-b) are intended to be fluidically connected to a refrigerant circuit.

3. Superconducting motor (100) according to one of claims 1 or 2, characterized in that the orifices (116) associated with the same coil (120) are separated by two orifices (116) associated with two other coils (120).

4. Aircraft comprising at least one superconducting engine (100) according to one of the preceding claims.

5. Aircraft according to the preceding claim, in dependence on claim 2, characterized in that said aircraft comprises a refrigerant circuit comprising a source of refrigerant fluid, said source of refrigerant fluid being fluidically connected to the openings (208a-b) of the channel (208) of the base (202) of the coil (120), said channel (208) being configured to be crossed by the refrigerant fluid between said openings (208a-b).

6. A method of manufacturing a coil (120) comprising: - a step (E30) of producing by additive manufacturing a U-shaped base (202) with two first columns (202a) and a first bottom (202b) fixed between the two first columns (202a), - a step of providing a plurality of sheets (204) made of a superconducting material, - a step (E10) of stacking said plurality of sheets (204), - a step (E20) of cutting said stack of sheets (204) so as to give said sheets (204) a U shape with two second columns (204a) forming the legs of the U and a second bottom (204b), and - a step (E40) of fixing said stack of sheets (204) on said base (202) by aligning each first column (202a) with second columns (204a) sheets (204) and the first background (202b) with the second backgrounds (204b) of the sheets (204).

7. Method for manufacturing a coil (120) according to claim 6, characterized in that the method comprises, prior to the step (E20) of cutting the stack of sheets (204), a step (El 1) of fixing the sheets (204) of the stack to each other.

8. Method for manufacturing a coil (120) according to claim 6, characterized in that the method comprises, after the step (E20) of cutting the stack of sheets (204), a step (E21) of fixing the sheets (204) of the U-shaped stack to each other.

Images