Electric machine and associated aircraft

Abstract

The invention relates to an electric machine comprising a stator (4) and a rotor inserted into a central circular opening of the stator, the stator comprising a yoke (4b) and a plurality of teeth (5) extending into the opening in a radial direction and a plurality of identical power assemblies (6). Each power assembly (6) comprises a coil (7) wound around one of the teeth and a power module (8) inserted into the stator and connected to the coil (7). Each power module (8) is arranged on the periphery of the stator (4) opposite the coil (7). Each power assembly (6) further comprises a coil holder (60). The power module (8) is separated from the coil (7) by the coil holder (60).

Description

[0001] DESCRIPTION

[0002] TITLE: ELECTRIC MACHINE AND ASSOCIATED AIRCRAFT

[0003] Technical field

[0004] The invention relates to the architecture of intelligent electrical machines known under the Anglo-Saxon term "smart motor", and more particularly the integration of power modules in said machines.

[0005] The invention further relates to an aircraft comprising such a machine.

[0006] Previous techniques

[0007] 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 to both new aircraft types and those already in operation, requiring the implementation of technological solutions to comply with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0008] Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. The Applicant takes into consideration the factors impacting 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.

[0009] 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.

[0010] This sustained research and development work focuses on new generations of aircraft engines, the weight reduction of aircraft, particularly through the materials used and lighter on-board equipment, the development of the use of electrical technologies to ensure propulsion, and, as an essential complement to technological progress, aeronautical biofuels.

[0011] Intelligent machines, known as "integrated modular motor drives" and "smart motors," integrate power components designed to power stator coils to improve the energy efficiency and reliability of said machines. The power electronics components are thus positioned close to the coils.

[0012] It is also known that stator coils and power electronic modules generate thermal losses increasing the temperature of their environment.

[0013] To prevent damage to stator coils and power electronic modules, the coil temperature and module temperature must each be below a respective maximum permissible temperature.

[0014] Document WO 2020 / 025884 discloses a smart motor type polyphase electric machine powered by an inverter.

[0015] The polyphase electric machine comprises electronic power modules integrated into an extension of the casing of said machine and supplying stator coils of said machine.

[0016] The arrangement of the power electronic modules on the housing extension allows the modules to be moved away from the stator coils to prevent overheating of the modules and coils, and minimizes the length of the electrical cables connecting the inverter to the electrical machine. However, the housing extension increases the size and mass of the machine.

[0017] As the machine installation space in an aircraft is limited, it is necessary to reduce the installation space.

[0018] In addition, it is necessary to reduce the mass of the machine.

[0019] Statement of the invention

[0020] The aim of the invention is to overcome all or part of these drawbacks, in particular by proposing an intelligent electrical machine having a reduced size and a reduced mass while benefiting from positioning the power electronics as close as possible to the coils.

[0021] To this end, the invention is the result of technological research aimed at very significantly improving the performance of electromechanical actuation systems, particularly in the aeronautical environment. In this sense, the invention contributes to reducing the environmental impact of aircraft. For this purpose, the invention relates to an electrical machine, comprising a stator, the stator comprising a central circular opening and a plurality of teeth extending into the opening in a radial direction of the stator and a plurality of identical power assemblies, each power assembly comprising a coil wound around one of the teeth and a power module inserted in the stator and configured to power said coil.

[0022] The power module of each power assembly is arranged on the periphery of the stator opposite the coil of said power assembly, each power assembly further comprising a coil support, said power module being separated from said coil by the coil support, said coil being in contact with a first face of the coil support and said power module being in contact with a second face of the coil support opposite the first face of the coil support to thermally and electrically insulate said coil from said module.The arrangement of the coil and the power module of each power assembly in the stator makes it possible to minimize the length of the conductive elements facilitating the power supply of said coil by said power module while limiting the thermal transfers between the coil and the power module and reducing the rising and falling edge distortions of a power supply signal to the coil delivered by the power module so that the power assembly does not include a device for filtering the power signal.

[0023] Furthermore, the insertion of the power module into the stator makes it possible to improve the mechanical protection of the power module, particularly in the variant where the latter is molded with the stator.

[0024] Preferably, each coil support comprises a first electrically insulating portion extending in the radial direction and a second thermally and electrically insulating portion extending in an axial direction of the stator, the coil of said power assembly being wound around the first portion, the first portion comprising a central opening housing one of the teeth of the stator, the second portion being inserted between the coil of said power assembly and the power module of said power assembly and comprising the first face in contact with said coil and the second face in contact with said power module.

[0025] Advantageously, the machine comprises conductive elements connecting the power module of each power assembly and each end of the coil of said power assembly, the conductive elements being integrated into the second portion of the coil support of said power assembly.

[0026] Preferably, the power module of each power assembly comprises an H-bridge comprising two identical branches, each branch comprising two switching cells connected in series and further comprising two power supply terminals between which said switching cells are positioned, a midpoint between said two cells of each branch being connected to one end of the coil of said power assembly. Advantageously, each switching cell comprises a diode and a transistor.

[0027] Preferably, the stator comprises an electrically insulating annular support, a first face of the annular support facing the coil of each power assembly, each power assembly further comprising a control module connected to the power module, the control module of each power assembly being arranged on a second face of the annular support opposite the first face.

[0028] Advantageously, the machine further comprises circular power supply tracks inserted into the annular support and preferably connected to the power supply terminals of each power module.

[0029] Preferably, the machine further comprises a casing and a thermally conductive layer, the stator being inserted into the casing, the thermally conductive layer being inserted between the casing and the power module of each power assembly, and being in contact with the casing and the power module of each power assembly.

[0030] An aircraft comprising an electrical machine as defined above is also proposed.

[0031] Preferably, the aircraft comprises an electromechanical actuation system into which the electric machine is integrated.

[0032] Brief description of the drawings

[0033] 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:

[0034] - figure [Fig 1] schematically illustrates an example of an aircraft according to an example of the invention,

[0035] - figure [Fig 2] schematically illustrates an exemplary embodiment of the stator of a machine according to an embodiment of the invention, - figure [Fig 3] schematically illustrates a partial longitudinal section of the stator according to said embodiment of the invention,

[0036] - figure [Fig 4] schematically illustrates an example of the realization of a power assembly, and

[0037] - figure [Fig 5] schematically illustrates an example of the construction of a power module.

[0038] Detailed description

[0039] We refer to figure 1 which schematically illustrates an example of an aircraft 1 comprising a direct current power supply bus 2 and an electrical machine 3 connected to the bus 2.

[0040] The electric machine 3 can be integrated into an electromechanical actuation system of the aircraft 1, for example a thrust reverser system, a winglet or flap actuation system.

[0041] Aircraft 1 as depicted is an airplane.

[0042] Alternatively, the aircraft is a helicopter.

[0043] The electric machine 3 can alternatively be integrated into space launchers or satellites.

[0044] The electric machine 3 comprises a stator 4 and a rotor 5 inserted in a central circular opening 4a of the stator 4.

[0045] The rotor 5 is separated from the stator 4 by an air gap.

[0046] Figure 2 schematically illustrates an example of the embodiment of the stator 4.

[0047] The stator 4 comprises a yoke 4b comprising a plurality of teeth 5 extending in a radial direction of the stator 4 in the central circular opening of the stator 4, and a plurality of power assemblies 6, the power assemblies preferably being identical.

[0048] Each power assembly 6 comprises a coil 7 wound around a tooth 5, a power module 8 inserted in the stator 4 and connected to the coil 7 of said power assembly 6 to power said coil 7, and a control module 9 connected to the power module 8 of said power assembly.

[0049] The power module 8 of each power assembly 6 is connected to the coil 7 of said assembly by conductive elements 67 (not shown in this figure), for example conductive tracks.

[0050] Each power assembly 6 further comprises a coil support 60 on which the coil 7 and the power module 8 of said assembly are arranged.

[0051] The power module 8 is arranged on the external circumference of the coil support 60 relative to a central axis of the stator 4 opposite the coil 7 of said power assembly.

[0052] The stator 4 further comprises an electrically insulating annular support 10 made, for example, of thermoplastic material.

[0053] The electrically insulating annular support 10 comprises a central circular opening into which the rotor 5 is inserted.

[0054] The rotor 5 is separated from the annular support 10 by an air gap.

[0055] The annular support 10 comprises a first face 10a facing the coil 7 of each power assembly 6 and a second face 10b opposite the first face 10a.

[0056] The control module 9 of each power assembly 6 is arranged on the second face 10b of the annular support 10.

[0057] The control modules 9 are arranged on the face of the annular support 10 opposite that facing the coils 7. As the coils 7 and the power modules 8 dissipate thermal losses, said control modules 9 are not heated by the coils 7 and the power modules 8, so that the temperature of the control modules 9 remains lower than the maximum temperature admissible by said modules 9. The service life of the control modules 9 is extended.

[0058] Figure 3 schematically illustrates a partial longitudinal section of the stator 4.

[0059] The power module 8 of each power assembly 6 is arranged on the periphery of the stator 4 opposite the coil 7 of said power assembly. The power module 8 is encapsulated in an electrically insulating and thermally conductive glue or resin 8a.

[0060] Each power assembly further comprises a coil support 60 having a first face 60a and a second face 60b.

[0061] The power module 8 of each power assembly 6 is separated from the coil 7 of said power assembly by the coil support 60.

[0062] The first face 60a of the coil support 60 is in contact with the coil 7 and the second face 60b of the coil support 60 is in contact with the power module 8.

[0063] This arrangement of the coil 7 and the power module 8 of each power assembly 6 in the stator 4 makes it possible to minimize the length of the conductive elements facilitating the supply of said coil by said power module while limiting the thermal transfers between the coil 7 and the power module 8.

[0064] Furthermore, since the length of the conductive elements is reduced, the rising and falling edge distortions of a coil supply signal output by the power module are reduced so that the power assembly does not include a coil supply signal filtering device.

[0065] Furthermore, the insertion of the power module 8 into the stator 4 makes it possible to improve the mechanical strength of the power module 8.

[0066] The power module 8 can be molded into the stator 4, further improving the mechanical strength of the power module 8.

[0067] The coil support 60 comprises a first electrically insulating portion 61 extending in the radial direction of the stator 4 and a second thermally and electrically insulating portion 62 extending in an axial direction of the stator 4 made for example of thermoplastic material.

[0068] The first portion 61 comprises the first face 60a in contact with the coil 7 and the second face 60b in contact with the power module 8.

[0069] The coil 7 of each power assembly is wound around the first portion 61 of the support 60 of said assembly. The first portion 61 comprises a central opening 63 housing a tooth 5 of the stator. The second portion 62 is inserted between the coil 7 of said power assembly and the power module 8 of said power assembly.

[0070] The thicknesses of the first and second portions 61, 62 may be identical or different.

[0071] As shown in Figure 3, the coil support 60 may be made in a single piece comprising the first and second portions.

[0072] Alternatively, the coil support 60 can be made from different parts separated and assembled together, for example a first part forming the first portion 61 and a second part forming the second portion 62.

[0073] Circular power supply conductive tracks 64 are inserted into the annular support 10 and connected to power supply terminals of each power module 8.

[0074] The 64 tracks are further connected to bus 2 so that the 64 tracks supply each power module 8 from bus 2.

[0075] Tracks 64 are further connected to each control module 9 to power each control module 9 from bus 2.

[0076] The machine 2 may further comprise a casing 65, the stator 4 being inserted into the casing 65.

[0077] A thermally conductive layer 66 made for example of aluminum is inserted between the casing 65 and the power module 8 of each power assembly 6, so that the thermally conductive layer 66 is in contact with the casing 65 and the power module 8 of each power assembly 6.

[0078] The thermally conductive layer 66 makes it possible to transfer calories dissipated by each power module 8 through the layer of resin or glue 8a encapsulating the power module 8 in the casing 65 by conduction to cool said power module 8.

[0079] Figure 4 schematically illustrates an exemplary embodiment of the power assembly 6. The conductive elements connecting the power module 8 of the power assembly 6 and each end of the coil 7 of the power assembly 6 are integrated into the second portion 62 of the support 60 of the coil 7.

[0080] The conductive elements comprise, for example, conductive tracks 67 embedded in the second portion 62 of the support 60 of the coil 7.

[0081] Figure 5 schematically illustrates an example of embodiment of the power module 8.

[0082] The power module 8 comprises in this embodiment an H-bridge comprising two identical branches 70, 71.

[0083] Each branch 70, 71 comprises two switching cells 72, 73 connected in series and extending between the two supply terminals 74, 75 connected to the tracks 64.

[0084] A first cell 72 of each branch 70, 71 comprises a first connection 72a connected to a first power supply terminal 74, a second opposite connection 72b, and a control input 72c connected to the control module 9 associated with the power module 8.

[0085] The second cell 73 of each branch 70, 71 comprises a first connection 73a connected to the second connection 72b of the first cell 72 of said branch, a second opposite connection 73b connected to the second power supply terminal 75, and a control input 73c connected to the control module 9 associated with the power module 8.

[0086] A midpoint 76 between the second connection 72b of the first cell 72 of the first branch 70 and the first connection 73a of the second cell 73 of the first branch 70 is connected to a first output 77 of the power module 8.

[0087] A midpoint 78 between the second connection 72b of the first cell 72 of the second branch 71 and the first connection 73a of the second cell 73 of the second branch 71 is connected to a second output 79 of the power module 8.

[0088] Each switching cell 72, 73 comprises for example a transistor 80 and a diode 81. The transistor 80 is for example a field effect transistor of the insulated gate type MOSFET (metal-oxide-semiconductor field effect transistor), of the insulated bipolar gate type IGBT (insulated-gate bipolar transistor), of the gallium nitride type GaN or of the silicon carbide type SiC.

[0089] The source of transistor 80 and the cathode of diode 81 are connected to the first connection 72a, 73a of cell 72, 73, the drain of transistor 80 and the anode of diode 81 are connected to the second connection 72b, 73b of cell 72, 73, and the gate of transistor 80 is connected to the control input 72c, 73c of cell 72, 73.

[0090] The power modules 8 allow the rotation of the rotor 4 to be controlled in the clockwise and counterclockwise directions according to the switching of the cells 72, 73.

[0091] The outputs 77, 79 are connected to the ends of the coil 7 via the conductive elements 67.

[0092] The power module 8 of each power assembly makes it possible, for example, to control the coil of said power assembly independently of control information from another device of the aircraft, in particular independently of the other power assemblies so that the power assemblies form a decentralized and autonomous machine control system.

Claims

CLAIMS 1. An electrical machine (3) comprising a stator (4), the stator comprising a central circular opening (4a) and a plurality of teeth (5) extending into the opening in a radial direction of the stator (4) and a plurality of identical power assemblies (6), each power assembly (6) comprising a coil (7) wound around one of the teeth and a power module (8) inserted in the stator and configured to power said coil, characterized in that the power module (8) of each power assembly (6) is arranged on the periphery of the stator (4) opposite the coil (7) of said power assembly, each power assembly further comprising a coil support (60), said power module (8) being separated from said coil (7) by the coil support (60),said coil (7) being in contact with a first face (60a) of the coil support (60) and said power module (8) being in contact with a second face (60b) of the coil support (60) opposite the first face of the coil support to thermally and electrically insulate said coil (7) from said module (8)., 2. Machine according to claim 1, wherein each coil support (60) comprises a first electrically insulating portion (61) extending in the radial direction and a second thermally and electrically insulating portion (62) extending in an axial direction of the stator (4), the coil (7) of said power assembly (6) being wound around the first portion (61), the first portion (61) comprising a central opening (63) housing one of the teeth (5) of the stator, the second portion (62) being inserted between the coil (7) of said power assembly and the power module (8) of said power assembly and comprising the first face (60a) in contact with said coil (7) and the second face (60b) in contact with said power module (8).

3. Machine according to claim 2, the machine comprising conductive elements (67) connecting the power module (8) of each power assembly (6) and each end of the coil (7) of said power assembly, the conductive elements (67) being integrated into the second portion (62) of the coil support (60) of said power assembly.

4. Machine according to one of claims 1 to 3, in which the power module (8) of each power assembly (6) comprises an H-bridge comprising two identical branches (70, 71), each branch comprising two switching cells (72, 73) connected in series and further comprising two power supply terminals (74, 75) between which said switching cells (72, 73) are positioned, a midpoint (76, 78) between said two cells (72, 73) of each branch being connected to one end of the coil (7) of said power assembly.

5. Electrical machine according to claim 4, in which each switching cell (72, 73) comprises a diode (81) and a transistor (80).

6. Electrical machine according to one of claims 1 to 5, in which the stator (4) comprises an electrically insulating annular support (10), a first face (10a) of the annular support facing the coil (7) of each power assembly (6), each power assembly further comprising a control module (9) connected to the power module (8), the control module (9) of each power assembly being arranged on a second face (10b) of the annular support opposite the first face (10a).

7. Machine according to claim 6, further comprising circular feed tracks (64) inserted into the annular support (10).

8. Machine according to one of claims 1 to 7, further comprising a casing (65) and a thermally conductive layer (66), the stator (4) being inserted into the casing, the thermally conductive layer being inserted between the casing (65) and the power module (8) of each power assembly (6), and being in contact with the casing and the power module of each power assembly.

9. Aircraft (1) comprising an electric machine (3) according to one of claims 1 to 8.

10. Aircraft according to claim 9, comprising an electromechanical actuation system into which the electric machine (3) is integrated.

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