Method for producing a stator for an aircraft rotary electric machine

Abstract

The invention relates to a method for producing a stator for an aircraft rotary electric machine (12), from a stator body (17) delimiting a stator cavity and provided with notches (1) which extend radially in a circumferential manner, each notch (1) being delimited by a radially outer transverse wall (22c) and two side walls (22a, 22b) extending radially between the transverse wall (22c) and a radially inner opening (23) of the notch (1), a cooling circuit comprising a cooling channel (19) being arranged inside each notch (1), the method comprising inserting, into each notch (1), an insulating separator (24), a rigid sealing plug (25) and a winding comprising turns of electrical conductors (20a, 20b), as well as depositing, in each notch (1), a sealing element (26) comprising an elastomer, the rigid sealing plug (25) and the sealing element (26) forming a closure system (25, 26) intended to close the opening of the notch (1), the method further comprising depositing an inner layer (27) of composite material covering the closure system (25, 26), the method being characterised in that the deposition of the inner layer (27) of composite material is carried out by tightly fitting the inner layer (27) of composite material into the stator cavity.

Description

[0001] DESCRIPTION

[0002] TITLE: Method for manufacturing a stator for a rotating electrical machine of an aircraft

[0003] The invention relates to a method for manufacturing a stator for a rotating electrical machine of an aircraft, in particular for an aircraft electric propulsion system. It also relates to the stator obtained by the method.

[0004] A rotating electrical machine, whether a motor or a generator, generally comprises a rotor configured to rotate on a shaft inside a bore of a fixed stator. Between the stator and the rotor is a narrow area called the air gap.

[0005] The interaction of the magnetic fields of the stator and rotor converts electrical energy into mechanical energy in the case of a motor, or mechanical energy into electrical energy in the case of a generator. During operation, losses in the electric machine can generate large amounts of thermal energy in the stator.

[0006] In high-power machines in particular, oil cooling of the stator can be preferable to air cooling. This is because oil has a higher specific heat capacity than air and therefore dissipates thermal energy from the stator more efficiently. Furthermore, oil can be used for both cooling and lubrication while being circulated by a single pump, which can help reduce aircraft weight.

[0007] In some cases, electrical machines may be equipped with cooling channels formed in notches of the stator, through which oil can circulate to remove heat from the stator, as described for example in document WO 2023 / 152479 A1.

[0008] An example of such cooling channels is illustrated in Figure 1. The slots 1 include a radially external portion 1a, in which the conductors (not shown) are housed, forming the stator windings by winding, and through which the oil flows. The slots 1 also include a radially internal portion housing a sealing system comprising a sealing plug 2 made of composite material, intended to restrict the passage of oil.Between the sealing plug 2 and the radially external part of the notch 1 (from the top down in the figure) are arranged successively: a first adhesive layer 3, a layer of fiber / resin composite material 4 designed to absorb the pressure exerted by the oil, a second adhesive layer 5, a layer of electrical insulation 6 ensuring electrical insulation between two adjacent conductor windings within the external part 1a, a third adhesive layer 7, and a rigid plate 8 for distributing the oil pressure forces. In addition, a layer 9 ensuring a smooth surface finish on the internal diameter of the stator is located on the inner end of the sealing plug 2.

[0009] The drawback of such a solution is its complex implementation, due to the use of a draping operation involving resin-pre-impregnated fabrics in very narrow notches 1 with large radii of curvature, which leads to a risk of porosity formation 10. Such porosity or delamination can cause unwanted oil circulation, particularly towards the air gap, with a risk of fire. Furthermore, the mechanical resistance to the pressure exerted by the oil, which occurs laterally through the adhesion between the sealing plug and the edges of the notch, can be reduced in the presence of porosity, which can lead to unwanted displacement of the sealing plug 2 towards the interior of the rotating machine.

[0010] A similar solution, illustrated in Figure 2, which has the same disadvantages, uses a foam or intumescent material filling plug 2.

[0011] It is also known to cover the sealing system with an internal layer of composite material to ensure the geometric regularity of the stator's inner end, for example, during a co-baking step using a counter-mold to guarantee the conformity of the stator's internal diameter. This process does not allow for easy inspection, repair, and recycling of the internal composite material layer.

[0012] The present invention aims to remedy these drawbacks. The invention thus relates to a method of manufacturing a stator for a rotating electrical machine of an aircraft, from a stator body delimiting a stator cavity and provided with slots which extend radially circumferentially, each slot being delimited by a radially external transverse wall and two lateral walls extending radially between the transverse wall and a radially internal opening of the slot, a cooling circuit comprising a cooling channel being disposed inside each slot and comprising the circulation of a coolant, in particular oil.

[0013] The method according to the invention comprises inserting into each notch an insulating separator, a rigid sealing plug, and a winding comprising windings of electrical conductors, as well as depositing in each notch a sealing element comprising an elastomer, the rigid sealing plug and the sealing element forming a sealing system intended to close the opening of the notch, the method further comprising depositing an internal layer of composite material covering the sealing system.

[0014] In the process according to the invention, the deposition of the inner layer of composite material is achieved by a tight fit (also called shrink fitting) of the inner layer of composite material in the stator cavity.

[0015] A fit is the combination of two dimensions of the assembly between an outer containing part (bore) and an inner contained part (shaft). The fit is considered tight when the shaft has a dimension larger than the bore. In this case, the diameter of the inner layer of composite material is larger than the diameter of the stator cavity.

[0016] Thus, thanks to the tight fit of the inner composite material layer within the stator cavity, on the inner surface of the stator body, there is no need for heat treatment of the composite material, and the conformity of the inner composite material layer can be easily checked prior to its insertion into the stator cavity. The assembly and disassembly of the inner composite material layer from the stator body are facilitated, as are the repairability and recyclability of the inner layer. The side walls defining each notch advantageously include a radial stop capable of limiting radial displacement of the sealing plug towards the interior of the stator, thereby eliminating the need for adhesives.

[0017] Thus, the rigid plug ensures the mechanical resistance of the sealing system to the pressure exerted by the coolant. The elastomer sealing element, in conjunction with the sealing plug, ensures the cooling circuit is sealed and can be selected to guarantee good compatibility with the coolant. This results in a leak-proof circulation of the coolant within the notches, as well as good mechanical resistance to the pressure exerted by the fluid on the sealing system.

[0018] The stator body can be disposed inside a holding and positioning device equipped with a chamfered area to guide the inner layer of composite material towards the inside of the stator body.

[0019] The composite material of the inner layer advantageously comprises a thermoplastic or thermosetting resin matrix and glass fibers.

[0020] The resin can be chosen from epoxy resins, phenolic resins, bismaleimide resins, polyimide resins, benzoxazine resins, phthalonitrile resins, polyaryletherketone resins, polyetherimide resins, and polyamide-imide resins.

[0021] The resin is preferably chosen from polyaryletherketone resins, and in particular polyetheretherketone resin, and polyetherimide resins.

[0022] The rigid sealing plug can seal the majority of the notch opening, with the remaining space between the sealing plug and the side walls at the opening being sealed by the sealing element.

[0023] The radial stop of the side walls can be formed by a shoulder on each side wall of the slot, cooperating with an associated shoulder on the sealing plug. The radial stop of the side walls can also be formed by an inclined portion of the side walls with a spacing between them that decreases radially towards the interior of the stator, and cooperating with a portion of the sealing plug having inclined side faces and a spacing between these side faces that decreases radially towards the interior of the stator. In other words, the side walls and the side faces can have a flared cross-section that widens towards the interior of the slot. The sealing plug can have a trapezoidal cross-section.

[0024] The sealing plug may include a composite material, which gives the sealing plug optimal rigidity.

[0025] The composite material advantageously comprises a resin matrix and glass fibers, which ensures dielectric compatibility and thermal stress resistance.

[0026] The resin can be chosen from epoxy resins, phenolic resins, bismaleimide resins, polyimide resins, benzoxazine resins, phthalonitrile resins, polyaryletherketone resins, polyetherimide resins, and polyamide-imide resins.

[0027] The elastomer for the sealing element can be chosen from fluorocarbon elastomers, silicone elastomers, fluorosilicone elastomers, chloroprene, butadiene-acrylonitrile copolymers, and ethylene-propylene-diene rubbers. When the coolant is oil, the fluoroelastomer marketed under the name Viton® by DuPont de Nemours is advantageously used as the elastomer.

[0028] Each notch may include a first electrical conductor located on the side of a first side wall and a second electrical conductor located on the side of a second side wall, the first electrical conductor and the second electrical conductor being electrically isolated from each other using the insulating separator.

[0029] The invention also relates to a stator obtained by the process described above.

[0030] It also relates to a method for repairing the stator, including a step of disassembling the internal layer of composite material.

[0031] The invention also relates to a rotating aircraft electric machine, comprising a stator as described above. The electric machine may be part of an aircraft electric propulsion system. The machine may contribute directly to propulsion, or indirectly through the generation of torques related to the propulsion system.

[0032] The invention also relates to an aircraft comprising a rotating electrical machine described above.

[0033] Other features and advantages of the present invention will become apparent from the following detailed description, of a non-limiting example of implementation, made with reference to the accompanying figures in which:

[0034] [Fig. 1], already described, is a partial cross-sectional view of a prior art aircraft rotating electrical machine stator slot, according to a first embodiment,

[0035] [Fig. 2] already described, is a detail view of a stator notch of a rotating electrical machine of an aircraft, according to the prior art, according to a second embodiment,

[0036] [Fig. 3] is a partial schematic cross-sectional view of a rotating aircraft electrical machine,

[0037] [Fig. 4] is a side view of the rotating electrical machine of [Fig. 3],

[0038] [Fig. 5] is a partial perspective view of a stator,

[0039] [Fig. 6] is a schematic cross-sectional view of a stator notch obtained by a process according to the invention, in accordance with a first embodiment,

[0040] [Fig. 7] is a schematic cross-sectional view of a stator notch obtained by a method according to the invention, in accordance with a second embodiment,

[0041] [Fig. 8] is a schematic cross-sectional view of a stator slot, during a first step of a stator manufacturing process according to the invention,

[0042] [Fig. 9] is a schematic cross-sectional view of a stator slot, during a second step in the stator manufacturing process; [Fig. 10] is a schematic cross-sectional view of a stator slot, during a third step in the stator manufacturing process.

[0043] [Fig. 11] is a schematic cross-sectional view of a stator slot, during a fourth step in the stator manufacturing process,

[0044] [Fig. 12] is a schematic cross-sectional view of a stator slot, useful for understanding the stator manufacturing process,

[0045] [Fig. 13] is a schematic cross-sectional view of a stator slot according to the invention, useful for understanding the stator manufacturing process,

[0046] [Fig. 14] is a first schematic cross-sectional view of the stator, during the fourth stage of the stator manufacturing process, and

[0047] [Fig. 15] is a second schematic cross-sectional view of the stator, during the fourth stage of the stator manufacturing process.

[0048] As illustrated in Figure 3, a rotating electrical machine 12 typically comprises a stator 13 and a rotor 14. The stator 13 is the stationary part of the machine 12. In the case of a motor, the stator is supplied with electricity and produces an inducing magnetic field. In the case of a generator, the stator produces a voltage induced by the changing magnetic field produced by the rotating rotor. The rotor 14 is the rotating part of the machine 12; the rotor currents produce a magnetic field (induced field) which reacts mechanically with the inducing field (stator) and produces a rotational torque.

[0049] As is known, a stator comprises a stator body 17, also called a core, which is made of a bundle of steel laminations and has notches 1. The notches 1 are, for example, longitudinally parallel to the axis of the body 17, said axis being coincident with the axis of rotation of the rotor 14 of the rotating electrical machine 12. These notches 1 extend radially circumferentially around the body and are separated from each other by teeth 15. The teeth 15 may each have at their radial end a tooth root which extends circumferentially on each side of said tooth so as to partially and respectively close the two notches adjoining this tooth. The stator 13 further comprises a polyphase winding consisting of several turns arranged in layers in the slots 1, with at least one winding per phase on each layer, said phases being connected together.For example, the stator may comprise three phases connected in delta or star, each phase comprising two windings connected in series or parallel.

[0050] A cooling circuit 16 can pass through slots 1 in the stator 13, through which a coolant such as oil can circulate to remove heat from the stator (Figure 4).

[0051] An example of a winding is illustrated in Figure 5.

[0052] As shown in Figure 5, the stator 13 comprises a stator body 17, electrical conductors 20a and 20b. A slot liner 18 may be provided in the slots 1, and a cooling channel 19, as shown in Figure 6, may be provided to guide a cooling fluid, which may be a liquid cooling fluid, typically oil.

[0053] The stator body 17 thus includes at least one slot 1 for receiving one or more electrical conductors 20a, 20b. The stator body 17 is typically configured to at least partially surround a rotor (not shown) of a generator, and typically carries a plurality of slots 1 extending substantially longitudinally about an axis of rotation of the rotor within the stator 13. The conductors of such an electrical machine are configured to interact with a rotating magnetic field generated by the rotor, either by permanent magnets or by electromagnetic windings. The stator body 17 includes a central body 17a and, in the illustrated arrangement, may be provided with a first and a second commutator 17b, 17c which can be configured to supply a flow of coolant to and from the respective ends of the central body 17a.

[0054] The central body 17a is configured to receive at least partially a rotor which is generally mounted for rotation inside a bore 21 of the stator assembly 13.

[0055] Thus, the central body 17a can have a hollow cylindrical shape, the hollow part of the cylindrical shape being configured to receive the rotor. One of the manifolds 17b, 17c can therefore act as an inlet manifold, configured to guide the coolant towards an inlet end of the slots, while the other can act as an outlet manifold, configured to collect the coolant flow from the outlet ends of the slots and return it to the coolant circuit.

[0056] The two collectors 17b, 17c can each be curved to form a circle. The two collectors 17b, 17c can be configured to contact and be fixed to the central body 17a. Each collector 17b, 17c can be hollow. Each collector 17b, 17c can be configured to receive one end of at least one electrical conductor 20a, 20b.

[0057] The stator body 17, in particular the central body 17a, may comprise a magnetizable material. The stator body 17, in particular the central body 17a, may comprise iron or another soft magnetic alloy. The stator body 17, in particular the central body 17a, may comprise a laminated material.

[0058] The stator body 17 comprises a plurality of slots 1, each configured to receive one or more electrical conductors 20a, 20b. Each slot 1 can be configured to receive at least one electrical conductor, and can be configured to receive two or more electrical conductors 20a, 20b arranged in parallel.

[0059] More specifically, the central body 17a can be in the form of an open tube. The central body 17a can be substantially symmetrical about a central axis. The two manifolds 17b, 17c can have substantially the same shape and / or size, but can also be formed differently. Their function is to act as a manifold to distribute the flow, which can arrive from a cooling circuit (not shown) at the ends of the multiple slots 1, to allow the cooling fluid to flow along the slots 1.

[0060] Figure 6 illustrates a cross-section of a notch 1 of a stator 13 according to the invention.

[0061] The notch 1 can be delimited by walls of the stator body 17, namely a first side wall 22a, a second side wall 22b, and an end wall 22c. The end wall 22c is a radially external transverse wall that connects the radially external ends of the side walls 22a and 22b. The walls 22a, 22b, and 22c belong to the stator body 17.

[0062] The first and second side walls 22a, 22b can be opposite walls, substantially facing each other. Viewed in cross-section as in Figure 6, the first and second side walls 22a, 22b can each have a radial depth dimension, more precisely a depth extending from an opening 23 in the notch 1 (Figure 8) to the end wall 22c substantially opposite the opening 23. The depth of the first side wall 22a can be substantially the same as that of the second side wall 22b. The first side wall 22a can be substantially parallel to the second side wall 22b, but may form a slight angle with the second side wall 22b due to the circumferential angular spacing of the walls, which may extend in a radial direction from the stator 13.

[0063] The end wall 22c may have a circumferential dimension, in particular a width in a tangential or circumferential direction. The width of the end wall 22c may be substantially perpendicular to the depth of the first and / or second side wall 22a, 22b. The width of the end wall 22c may be less than the depth of the first and / or second wall 22a, 22b. The side walls 22a, 22b and the end wall 22c may define two corners in an area where the walls meet. The two corners may be arched.

[0064] The electrical conductor(s) are at least partially arranged in at least one slot 1. In the arrangement illustrated in Figure 6, each slot 1 may accommodate both a first electrical conductor 20a and a second electrical conductor 20b. The first electrical conductor 20a and the second electrical conductor 20b may have substantially the same shape and cross-sectional size, but they may also have different sizes or shapes. The first and / or second electrical conductor 20a, 20b may each have at least one substantially straight edge.

[0065] The first and / or second electrical conductor 20a, 20b may each have two substantially straight edges when viewed in cross-section. The two substantially straight edges of each electrical conductor 20a, 20b may lie on opposite sides of the conductor 20a, 20b relative to each other. Each electrical conductor 20a, 20b may have a width and a depth, the depth being greater than the width, and the substantially straight edge being arranged to extend in the direction of the depth. The electrical conductors 20a, 20b may each have a symmetrical cross-section. The first and second electrical conductors 20a, 20b may be elongated, as illustrated in Figure 5.

[0066] The first electrical conductor 20a and the second electrical conductor 20b are electrically insulated from each other by means of an insulating separator 24, which is located on the radially external end of the slot 1, for example, in the bottom of the slot 1. The insulating separator 24 comprises two transverse walls 24a connected by a radial wall 24b. The insulating separator 24 thus defines two lateral compartments separated by the radial wall 24b, each receiving an electrical conductor 20a, 20b. The transverse walls 24a help to equalize the radial pressure exerted by the coolant, while the radial wall 24b primarily provides the electrical insulation.

[0067] The material of the insulating separator 24 can be any dielectric material, in particular a rigid dielectric material, especially a composite material.

[0068] Each notch 1 can be configured to extend from an axial end opening, located at one end of the central body 17a, to a second axial end opening, located at a second end of the central body 17a, so that the conductor and its coolant can pass axially from one end of the central body 17a to the other end of the central body 17a.

[0069] The notch 1 and the first and / or second electrical conductor 20a, 20b can each be configured to extend from one of the two commutators 17b, 17c of the stator body 17 to the other of the two commutators 17b, 17c. The first and second electrical conductors 20a, 20b can be made of a single piece of unit material. The first and second electrical conductors 20a, 20b can be made of an electrically conductive material, such as copper. For example, the first and second electrical conductors 20a, 20b can comprise insulated copper elements or bars. The stator 13 can be part of a multiphase machine. Therefore, the conductors 20a, 20b of the stator 13 can comprise more than one phase. For example, the conductors can comprise two or more phases. Thus, the conductors can comprise three phases.Each slot 1 can therefore include two-phase or three-phase conductors in a single slot.

[0070] The cooling channel 19, along which the coolant can flow, is located inside the notch 1, between the electrical conductors 20a, 20b. The cooling channel 19 can be configured so that the fluid can flow from one end of the stator body 17 to the other end of the stator body 17.

[0071] The stator 13 also includes a sealing system. The purpose of this sealing system is to prevent coolant from leaking into the air gap between the stator 13 and the rotor 14.

[0072] The sealing system includes a rigid sealing plug 25 which is arranged radially between the insulating separator 24 and the opening 23 of the notch, located at the radially internal end of the notch 1. The sealing plug 25 seals at least a part of the opening 23 of the notch 1.

[0073] The sealing system also includes a sealing element 26 (a sealing gasket) which includes an elastomer, preferably an elastomer sealing element.

[0074] The radial movement of the sealing plug 25 towards the interior of the stator (i.e. towards the rotor) is limited by a radial stop of the stator body formed by a surface of the side walls 22a, 22b which presses radially on a corresponding surface of the sealing plug 25 when the oil exerts pressure on the plug 25.

[0075] In particular, each lateral wall 22a, 22b of the notch 1 may have a surface that cooperates with a corresponding surface of the sealing plug 25. For example, a shoulder of each lateral wall 22a, 22b forms a radial stop for a corresponding shoulder of the rigid plug 25 (Figure 6). Alternatively, an inclined portion of the lateral walls having a spacing between the lateral walls 22a, 22b that decreases radially towards the interior of the stator, cooperates with a portion of the rigid plug 25 having inclined lateral faces 25a and a spacing between said lateral faces 25a that decreases radially towards the interior of the stator (Figure 7). In this latter case, the sealing plug 25 advantageously has a trapezoidal cross-section.

[0076] The sealing plug 25 is advantageously made of a composite material comprising a resin matrix and glass fibers, in particular an epoxy resin. The resin can be selected from epoxy resins, phenolic resins, bismaleimide resins, polyimide resins, benzoxazine resins, phthalonitrile resins, polyaryletherketone resins, polyetherimide resins, and polyamide-imide resins.

[0077] Polyaryletherketone resins, polyetherimide resins, and polyamide resins are advantageous due to their inherent sealing properties. They are less susceptible to oil permeation and less prone to micro-cracking than epoxy resins.

[0078] The sealing plug 25 can occupy most of the opening 23 of the notch 1. The elastomer sealing element 26 can be inserted into the lateral gap(s) 28 (Figure 9) that remain between the sealing plug 25 and each lateral wall 22a, 22b of the notch 1 (Figures 6 and 7), and in particular in a radially internal end of the gaps 28. The sealing element 26 can also cover the radially internal surface of the plug 25 as well as the radially internal surface of the stator body 17 in the vicinity of the notch 1.

[0079] Alternatively, the sealing element 26 may only cover the radially internal end of the lateral gaps 28 (figure 13).

[0080] The elastomer of the sealing element 26 can be chosen from fluorocarbon elastomers, silicone elastomers, fluorosilicone elastomers, chloroprene, butadiene-acrylonitrile copolymers, and ethylene-propylene-diene rubbers.

[0081] The sealing system 25, 26 can be covered by an inner layer 27 of composite material ensuring the geometric regularity of the inner end of the stator 13. The composite material of the inner layer 27 can be the same as that of the sealing plug 25. An example of manufacturing a stator 13 according to the invention will now be described, with reference to Figures 8 to 13.

[0082] In a first step, an insulating separator 24 is inserted into each notch 1 (Figure 8). The sealing plug 25 is then inserted into the notch 1, for example, through the longitudinal ends of the notch 1, between the insulating separator 24 and the opening of the notch 1 (Figure 9). The sealing plug 25 can be manufactured ex situ by producing a laminated panel of composite material, which is then machined to the necessary tolerances to ensure proper insertion into the notches 1 and functional retention. The sealing plug 25 is then inserted through the ends of the notch 1, between the insulating separator 24 and the opening of the notch 1.

[0083] The winding comprising the electrical conductors 20a, 20b is then inserted into the slot 1, for example, from the longitudinal ends of the slot 1 or from inside the stator if accessibility permits (Figure 10). The elastomer sealing element 26 is then deposited, and the inner layer 27 of composite material is deposited (Figure 11). As mentioned above, several options for depositing the elastomer sealing element 26 are possible. The elastomer sealing element 26 can be deposited as a vulcanized film on the inner surface of the stator 13 (Figure 12). A second option is to deposit the elastomer sealing element 26 selectively in the lateral cavities 28 to be filled, in the form of elastomer filaments deposited manually or by additive manufacturing (Figure 13).

[0084] According to the method according to the invention, the deposition of the inner layer 27 of composite material is achieved by a tight fit (shrink fitting) of the rigid inner layer 27 of composite material inside the stator body 17.

[0085] The inner layer 27 of composite material is cylindrical in shape. It is consolidated beforehand to ensure the regularity (homogeneity) and concentricity of the outer diameter of the inner layer 27. This conformity of the outer diameter is achieved using a tool, such as a bladder, placed inside a tube in which the inner layer 27 is wound.

[0086] As illustrated in Figure 14, the pre-consolidated, cylindrical inner layer 27 is first pre-positioned in the vicinity of the stator 13, using a guide support 29. The guide support allows the inner layer 27 to be positioned coaxially with the stator body 17. The external diameter of the tubular inner layer 27 is greater than or equal to the internal diameter of the stator body 17.

[0087] The stator body 17 is arranged inside a retaining and positioning device 30. The retaining and positioning device 30 is advantageously provided with a chamfered area 30a allowing better guidance of the inner layer 27 towards the inside of the stator body 17.

[0088] The rigid inner layer 27 of composite material is then forcibly inserted, by pressure and plastic deformation, without heat treatment, into the stator cavity 31, on the stator body 17 (figure 15).

[0089] Alternatively, heating the inner layer 27 of composite material can be considered to promote its plastic deformation. Cooling the inner layer 27 of composite material to a very low temperature can also be considered to facilitate its insertion into the stator cavity.

[0090] The inner layer 27 of composite material can be forcibly disassembled by cooling the inner layer 27 of composite material.

Claims

Demands 1. A method for manufacturing a stator (13) for a rotating electrical machine of an aircraft (12), starting from a stator body (17) defining a stator cavity (31) and having slots (1) extending radially circumferentially, each slot (1) being delimited by a radially external transverse wall (22c) and two lateral walls (22a, 22b) extending radially between the transverse wall (22c) and a radially internal opening (23) of the slot (1), a cooling circuit (16) comprising a cooling channel (19) being disposed inside each slot (1) and comprising the circulation of a coolant, in particular oil, the method comprising inserting into each slot (1) an insulating separator (24), a rigid sealing plug (25), and a winding comprising windings of electrical conductors (20a, 20b),as well as the deposition in each notch (1) of a sealing element (26) comprising an elastomer, the rigid sealing plug (25) and the sealing element (26) forming a sealing system (25, 26) intended to seal the opening (23) of the notch (1), the method further comprising the deposition of an inner layer (27) of composite material covering the sealing system (25, 26), the method being characterized in that the deposition of the inner layer (27) of composite material is achieved by a tight fit of the inner layer (27) of composite material in the stator cavity (31).

2. Method according to claim 1, characterized in that the stator body (17) is disposed inside a holding and positioning device (30) provided with a chamfered area (30a) allowing the inner layer (27) of composite material to be guided into the inside of the stator body (17).

3. Method according to claim 1 or 2, characterized in that the composite material of the inner layer (27) of composite material comprises a thermoplastic or thermosetting resin matrix and glass fibers.

4. A method according to any one of claims 1 to 3, characterized in that the lateral walls (22a, 22b) delimiting each notch (1) comprise a radial stop capable of limiting radial displacement of the sealing plug (25) towards the interior of the stator (13) 5. A method according to any one of claims 1 to 4, characterized in that the radial stop of the side walls (22a, 22b) is constituted by a shoulder of each side wall (22a, 22b) of the notch (1), cooperating with an associated shoulder of the sealing plug (25), or by an inclined portion of the side walls having a spacing between the side walls (22a, 22b) which decreases radially towards the interior of the stator (13), and cooperating with a portion of the sealing plug (25) provided with inclined side faces (25a) and having a spacing between said side faces which decreases radially towards the interior of the stator (13).

6. A method according to any one of claims 1 to 5, characterized in that the sealing plug (25) comprises a composite material comprising a resin matrix and glass fibers.

7. A process according to claim 6, characterized in that the resin is selected from epoxy resins, phenolic resins, bismaleimide resins, polyimide resins, benzoxazine resins, phthalonitrile resins, polyaryletherketone resins, polyetherimide resins, and polyamide-imide resins.

8. A method according to any one of claims 1 to 7, characterized in that the elastomer of the sealing element (26) is selected from fluorocarbon elastomers, silicone elastomers, fluorosilicone elastomers, chloroprene, butadiene-acrylonitrile copolymers, and ethylene-propylene-diene rubbers.

9. A method according to any one of claims 1 to 8, characterized in that each notch (1) comprises a first electrical conductor (20a) located on the side of a first lateral wall (22a) and a second electrical conductor (20b) located on the side of a second lateral wall (22b), the first electrical conductor (20a) and the second electrical conductor (20b) being electrically insulated from each other using the insulating separator (24).

10. Stator (13) for rotating electrical machine of aircraft (12), characterized in that it is obtained by a process according to any one of claims 1 to 9.

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