COIL SYSTEM FOR A SUPERCONDUCTIVE MOTOR

Abstract

COIL SYSTEM FOR A SUPERCONDUCTIVE MOTOR The invention relates to a superconducting coil system (200) comprising a coil (220) of superconducting ribbons (204), stacked against each other and wound so as to form straight sections passing through a first orifice (116) and a second orifice (116) and a winding (210) of at least one turn comprising straight subsections (210a-b) passing through each of the two orifices (116) and a heat exchanger system (250) comprising for each orifice (116), a thermal block (252) arranged in said orifice (116) and positioned against an edge of each ribbon (204) disposed in the same orifice (116), at least one pipe (253) embedded in the thermal block (252) and through which a heat transfer fluid flows,and two heat-resistant plates (256) disposed in said orifice (116) and arranged on either side of the thermal block (252), and ribbons (204) disposed in the same orifice (116) where each heat-resistant plate (256) is fixed against the thermal block (252). With such an arrangement, the heating of the coil system is limited. Fig. 2,

Description

Title of the invention: COIL SYSTEM FOR A SUPERCONDUCTIVE MOTOR technical field

[0001] The present invention relates to the general field of superconducting motors and more particularly to a coil system for a superconducting motor as well as to a superconducting motor comprising a plurality of such coil systems. PREVIOUS STATE OF THE ART

[0002] A superconducting motor comprises a rotor with a rotor core made of a ferromagnetic material. The rotor core is cylindrical and has a central bore into which a motor shaft is fitted and rigidly fixed.

[0003] The rotor also includes permanent magnets fixed to the rotor core on its periphery. There are several permanent magnets distributed angularly and regularly around the rotor core and spaced apart from each other. Conventionally, the permanent magnets are magnetized radially with respect to a longitudinal axis and alternately from one point to the next.

[0004] The superconducting motor comprises a stator located outside the rotor and having a stator core made of a ferromagnetic material. The stator core is generally cylindrical and, on its cylindrical face facing the rotor, has orifices distributed angularly and regularly around the rotor. The orifices are arranged in pairs, and the two orifices in each pair are separated by a tooth that is a single piece and made of the same material as the stator core.

[0005] For each pair of orifices, the stator includes a coil which is wound around the tooth and which is made of a superconducting material.

[0006] In operation, each coil is electrically powered to generate a magnetic field which interacts with the permanent magnets to drive them into rotation with the rotor and the motor shaft.

[0007] Although such an arrangement gives good results, the coils undergo significant heating which limits their performance and it is therefore desirable to find an arrangement which improves the situation. Description of the invention

[0008] An object of the present invention is to propose a coil system which can be put in place in a superconducting motor and whose heating is limited to improve performance.

[0009] To this end, a coil system for a superconducting motor is proposed, comprising a first and a second orifice, said coil system comprising:

[0010] - a reel made up of several ribbons made of a material superconductors, with rectangular cross-sections, stacked one against the other and wound so as to form a first straight section intended to pass through the first orifice and having a first end and a second end, a second straight section intended to pass through the second orifice and having a first end and a second end, and a winding of at least one turn connecting the second ends together and comprising straight subsections intended to pass through one of the two orifices and curved subsections intended to be outside the orifices and connecting together the straight sections and subsections, and

[0011] - a heat exchanger system comprising for each orifice to be through which the coil passes:

[0012] - a thermal block intended to be arranged in said orifice and positioned against a slice of each ribbon placed in the same opening,

[0013] - at least one pipe embedded in the thermal block and intended to be traversed by a heat transfer fluid, and

[0014] - two radiator plates intended to be placed in said orifice and arranged on either side of the thermal block and ribbons arranged in the same orifice where each radiator plate is fixed against the thermal block.

[0015] With such an arrangement, heating of the coil system is limited.

[0016] Advantageously, the pipe passing through one thermal block and the pipe passing through the other thermal block of the same heat exchanger system are fluidly connected by a connecting pipe.

[0017] Advantageously, each radiator plate is made of ceramic.

[0018] Advantageously, the thermal block is made of cupronickel.

[0019] The invention also proposes a superconducting motor comprising:

[0020] - a rotor with a rotor core carrying permanent magnets and free to rotate around a longitudinal axis,

[0021] - a stator disposed outside the rotor and comprising a stator core through by several pairs of first and second orifices distributed angularly and regularly around the rotor, and

[0022] - for each pair of ports, a coil system according to one of the variants previous ones. Brief description of the drawings

[0023] The features of the invention mentioned above, as well as others, will become clearer upon reading the following description of an example of implementation, the said description being made in relation to the attached drawings, among which:

[0024] [Fig. 1] is a cross-sectional view of a superconducting motor according to the invention,

[0025] [Fig.2] is a perspective view of a coil system according to the invention, and

[0026] [Fig.3] is a cross-sectional view of a coil system according to the invention.

[0027] DETAILED STATEMENT OF IMPROVEMENTS

[0028] Fig. 1 shows a superconducting motor 100 according to the invention seen in section by a plane perpendicular to a longitudinal axis X of said superconducting motor 100, and Figs. 2 and 3 show a coil system 200 according to the invention and implemented in the superconducting motor 100.

[0029] The superconducting motor 100 comprises a rotor 102 having 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 has a central bore 06 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.

[0030] The rotor 102 also includes permanent magnets 110 fixed to the rotor core 104 on its periphery. 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. Preferably, the permanent magnets 110 are magnetized radially with respect to the longitudinal axis X and alternately from one point to the next.

[0031] The superconducting motor 100 also includes a stator 112 which is disposed outside the rotor 102 and which has a stator core 14 made of a ferromagnetic material such as all the iron alloys used for electrical machines. The stator core 114 has a generally cylindrical shape coaxial with the longitudinal axis X.

[0032] At the level of its cylindrical face which is oriented towards the rotor 102, the stator core 114 has orifices 116, here in the form of slots which open out facing the rotor 102. According to an embodiment not shown, the orifices 116 can be in the form of tunnels passing through the stator core 114.

[0033] The orifices 116 extend parallel to the longitudinal axis X.

[0034] There are several orifices 116 (here sixteen in number) which are distributed angularly and regularly around the rotor 102 and which are arranged in pairs. The two orifices 116 of the pair are separated by a tooth 118 that is one-piece and made of one material with the stator core 114. In the case of tunnel-shaped orifices 116, the orifices 116 are embedded in the stator core 114.

[0035] For each pair of ports 116, the stator 112 includes a coil system 200 installed in the pair of ports 116 of the stator core 114.

[0036] The coil system 200 comprises a coil 220 made up of several rectangular-section ribbons 204, here three in number, which are joined together by their large surfaces, one against the other so as to form a stack, and wound upon themselves to form generally flat turns. Each ribbon 204 is made of a superconducting material and two successive ribbons 204 in the stack are electrically insulated from each other by a layer of an electrically insulating material, such as a layer of polyimide varnish, disposed between them, that is to say, an electrically insulating material is disposed between the large contact surfaces of the two successive ribbons 204.

[0037] The coil 220 has a first straight section 202a which passes through a first orifice 116 of the pair of orifices 116, a second straight section 202b which passes through a second orifice 116 of the pair of orifices 116. Each section is thus made up of a stack of ribbons 104.

[0038] The first section 202a and the second section 202b each have a first end 206a-b electrically connected to a power supply and a second end 208a-b. All the ribbons 204 are electrically connected to the power supply at each first end 206a-b, i.e., the current flows through all the ribbons 204 of the reel 220. The ribbons 204 are thus electrically insulated from each other along the path between the first ends 206a-b but electrically connected at the first ends 206a-b.

[0039] The coil 220 also includes a winding 210 of at least one turn which connects the second ends 208a-b together. The winding 210 has straight subsections which pass through one of the two orifices 116 and curved subsections which are outside the orifices 116 and connect the straight sections and subsections together.

[0040] In the embodiment of the invention shown in [Fig.2], the winding 210 has a single turn and comprises a first straight subsection 210a which passes through the second orifice 116, a second straight subsection 210b which passes through the first orifice 116, a third curved subsection 210c which connects the second end 208a of the first section 202a to the first subsection 210a, a fourth curved subsection 210d which connects the first subsection 210a to the second subsection 210b and a fifth subsection 210e which connects the second subsection 210b to the second end 208b of the second section 202b.

[0041] Of course, the arrangement may be different depending on the number of turns of the winding 210.

[0042] The ribbons 204 of each section 202a-b and of each straight subsection 210a-b which pass through an orifice 116 are arranged next to each other joined by their large surfaces.

[0043] The coil system 200 also includes a heat exchanger system 250.

[0044] For each orifice 116 through which the coil 220 passes, the heat exchanger system 250 comprises a thermal block 252 made of a thermally conductive material with, in particular, a thermal conductivity greater than 10 W / m / K. The thermal block 252 is, for example, made of cupronickel.

[0045] The thermal block 252 is positioned against a slice of each ribbon 204 which is in the same orifice 116 as it, that is to say the slice of each ribbon 204 of the section 202a-b and of each straight subsection 210a-b which pass through the same orifice 116. The heat of the ribbons 204 is thus transmitted to the thermal block 252.

[0046] Each thermal block 252 is thus arranged in an orifice 116 and is, in addition, traversed by at least one pipe 253 (here two in number) of the heat exchanger system 250. Each pipe 253 is therefore embedded in the associated thermal block 252 and extends along the orifice 116 parallel to the longitudinal axis X.

[0047] Each pipe 253 carries a heat transfer fluid from a heat transfer fluid reservoir and is driven by suitable systems such as a pump. The heat transfer fluid is, for example, gaseous helium. The heat transfer fluid is cooler than the heat block 252 in order to dissipate heat.

[0048] In the embodiment of the invention presented here, each pipe 253 passing through an orifice 116 is fluidly connected to a pipe 253 passing through the other orifice 116 of the pair of orifices 116, by a connecting pipe 254 which is shown here in the form of an arc and which is against the third subsection 210c and the fifth subsection 210e of curved form. The connecting pipes 254 are shown here in two-dot dashed lines.

[0049] The heat exchanger system 250 also includes, for each thermal block 252, two radiator plates 256 which are arranged in the orifice 116 corresponding to said thermal block 252. The radiator plates 256 are arranged on either side of the thermal block 252 and the ribbons 204 of the section 202a-b and of each straight subsection 210a-b which pass through the same orifice 116. Each radiator plate 256 thus extends vertically over the height of the ribbons 204, corresponding to their large surfaces, and over the height of the thermal block 252.

[0050] Each heat sink plate 256 is further fixed against the thermal block 252, for example by welding. Each heat sink plate 256 is made of a thermally conductive material, in particular with a thermal conductivity greater than at 100 W / m / K. Each 256 radiator plate is for example made of ceramic such as aluminium oxide (A12O3).

[0051] Each radiator plate 256 can also be coated with a metallic layer such as copper which facilitates connection by soldering to the thermal block 252 when it is also made of metal such as cupronickel.

[0052] With such an arrangement, the heat from the ribbons 204 is dissipated better than in the case of the prior art.

[0053] The rotor 102 and the stator 112 are housed here in a motor housing 122 closed at both ends by sides, at least one of which has a central opening allowing the passage of the motor shaft 108. The stator 112 is fixedly mounted inside the motor housing 122 while the rotor 102 and the motor shaft 108 are mounted freely to rotate inside the motor housing 122, for example by means of bearings.

[0054] In operation, each coil 220 is electrically powered to generate a magnetic field which interacts with the permanent magnets 110 to drive them into rotation with the rotor 102 and the motor shaft 108.

[0055] Here, the superconducting motor 100 has an inner cylinder 124 and an outer cylinder 126 which are coaxial with the longitudinal axis X.

[0056] 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.

[0057] The inner cylinder 124 and the outer cylinder 126 extend between the two sides to which they are hermetically fixed to delimit between themselves and the two sides, a chamber 128 in which the stator 112 is housed and which can be evacuated.

Claims

Demands

1. Coil system (200) for a superconducting motor (100) having a first and a second orifice (116), said coil system (200) comprising: - a coil (220) made of several ribbons (204) made of a superconducting material, with a rectangular cross-section, stacked against each other and wound so as to form a first straight section (202a) intended to pass through the first orifice (116) and having a first end (206a) and a second end (208a), a second straight section (202b) intended to pass through the second orifice (116) and having a first end (206b) and a second end (208b),and a winding (210) of at least one turn connecting the second ends (208a-b) together and comprising straight subsections (210a-b) intended to pass through one of the two orifices (116) and curved subsections (210c-e) intended to be outside the orifices (116) and connecting the straight sections (202a-b) and subsections (210a-b) together, and - a heat exchanger system (250) comprising, for each orifice (116) to be passed through by the coil (220): - a thermal block (252) intended to be arranged in said orifice (116) and positioned against an edge of each ribbon (204) disposed in the same orifice (116), - at least one conduit (253) embedded in the thermal block (252) and intended to be traversed by a heat transfer fluid,and - two radiator plates (256) intended to be disposed in said orifice (116) and arranged on either side of the thermal block (252) and strips (204) disposed in the same orifice (116) where each radiator plate (256) is fixed against the thermal block (252).

2. Coil system (200) according to claim 1, characterized in that the pipe (253) passing through one thermal block (252) and the pipe (253) passing through the other thermal block (252) of the same heat exchanger system (250) are fluidly connected by a connecting pipe (254).

3. Coil system (200), according to any one of claims 1 or 2, characterized in that each radiator plate (256) is ceramic.

4. Coil system (200) according to any one of claims 1 to 3, characterized in that the thermal block (252) is made of cupronickel.

5. Superconducting motor (100) comprising: - a rotor (102) with a rotor core (104) carrying permanent magnets (110) and movable in rotation about a longitudinal axis (X), - a stator (112) disposed outside the rotor (102) and comprising a stator core (114) through which several pairs of a first and a second orifice (116) are passed angularly and regularly around the rotor (102), and - for each pair of orifices (116), a coil system (200) according to any one of the preceding claims.

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