Electrical conductor

Abstract

The invention relates to an electrical conductor (1) intended to be received in a slot (8) in a stator mass (18) of a stator (13) of a rotary electric machine (12), the conductor comprising one or more strands (2), at least one strand being formed of a hollow wire configured such that a coolant can pass therethrough, the conductor comprising at least one leg, in particular two legs (3) connected by a coil head (4), the leg comprising a straight portion (5) intended to extend rectilinearly along an axis Y within the slot and at the outlets of the slot on either side of the stator mass, the straight portion having, for at least one strand formed of a hollow wire, a plurality of orifices for the passage of the coolant (7), the plurality of orifices comprising at least two end orifices (17) intended to be arranged on either side of the stator mass.

Description

[0001] Description

[0002] Title: Electrical Driver

[0003] The present invention claims priority from French application 2403052 filed on March 26, 2024, the content of which (text, drawings and claims) is incorporated herein by reference.

[0004] Technical field

[0005] The present invention relates to rotating electrical machines and more particularly to the stators of such machines. The invention relates in particular to hollow electrical conductors received in stator slots, allowing the passage of a cooling fluid therein.

[0006] The machines may be synchronous or asynchronous, with alternating current. They may be traction or propulsion machines for electric motor vehicles (Battery Electric Vehicle) and / or hybrid vehicles (Hybrid Electric Vehicle - Plug-in Hybrid Electric Vehicle), such as individual cars, vans, trucks or buses. The invention also applies to rotating electrical machines for industrial and / or energy production applications, in particular naval, aeronautical or wind power.

[0007] Prior art

[0008] Cooling the stators of rotating electrical machines is essential for their proper functioning.

[0009] It is known from the prior art to circulate a cooling fluid inside hollow electrical conductors, in particular of the pin type, received in notches of the stator. However, it is difficult to circulate a cooling fluid at the level of the coil head of the conductors because the conductor is folded there, which reduces or even can block the fluid passage section. This constraint greatly limits the cooling efficiency.

[0010] The passage of the coolant inside the conductors also requires a specific configuration to ensure the connection of the conductors to both the coolant circuit and the power supply. Major modifications to the fluid manifolds at the coolant inlet and outlet may be necessary to allow the integration of the conductor phase connectors. These modifications can pose space problems and production difficulties.

[0011] Application DE 10 2021 119405 describes hollow, pin-shaped conductors that are partially traversed by a cooling fluid. A deflection element leading to a protruding branch is connected to one leg of the conductor. Such a configuration of the conductor makes it difficult to manufacture and reduces its compactness.

[0012] Application US 2021 / 0036567 discloses conductors through which cooling oil circulates, which are connected together at their ends by an insert, which may be a printed circuit. Distribution channels to and from this insert allow the oil supply.

[0013] Application FR 3 105 631 concerns hollow U-shaped conductors whose free ends are housed inside an annular-shaped casing in which a cooling fluid circulates. The cooling fluid passes from one end of each conductor to the other, without side orifices. The inlet and outlet are on the same side, which causes high pressure losses.

[0014] Applications DE 10 2019 112389, DE 10 2018 207155, US 2021 / 0091619 and DE 102019 135140 call for additional parts to allow the circulation of the cooling fluid, in particular fluid collectors, connecting parts and other segments, connected to the conductors to allow the circulation of a cooling fluid within stators. Application US 2021 / 0091619 in particular presents conductors whose cross-section is rectangular at the winding head and circular at the ends.

[0015] There is therefore a need to propose a simple solution to cool the stator and its set of electrical conductors, in particular making it possible to avoid circulating a cooling fluid in the coil heads of the electrical conductors, and which does not add additional constraints regarding the integration of the phase connectors.

[0016] Statement of the invention

[0017] The invention aims to meet this need and achieves this, according to one of its aspects, by means of an electrical conductor intended to be received in a notch of a stator mass of a stator of a rotating electrical machine, the stator mass comprising a plurality of notches for receiving a plurality of electrical conductors, the electrical conductor comprising one or more strands, at least one strand being formed of a hollow wire configured to be traversed by a cooling fluid, the electrical conductor comprising at least one leg, in particular two legs connected by a coil head, the leg comprising a straight portion intended to extend rectilinearly along a Y axis in the notch and at the outlets of the notch on either side of the stator mass, the straight portion having for at least one strand formed of a hollow wire a plurality of orifices for the passage of the cooling fluid,the plurality of orifices comprising at least two end orifices intended to be arranged on either side of the stator mass.,

[0018] The electrical conductor may be I-shaped. Alternatively, the electrical conductor may be bent, such as into a U-shaped pin. Alternatively, the electrical conductor may be wound, so as to form a continuous wire coil.

[0019] One of the end ports may provide an inlet for the coolant into the electrical conductor, while another end port on the other side of the stator mass may provide an outlet for the coolant from the electrical conductor. The coolant may flow axially along the Y axis of the leg in the electrical conductor, from an inlet end port to an outlet end port.

[0020] The two end holes may not be the ends of the hollow of the electrical conductor wire.

[0021] In the invention, there are few pressure losses in cooling. In addition, cooling is improved due to the fact that there are several cooling fluid circulation conduits in parallel, in particular one per hollow wire.

[0022] Furthermore, any bottleneck in the circulation of the cooling fluid is avoided, particularly at the level of the coil heads.

[0023] The electrical conductor according to the invention makes it possible, by the arrangement of its end orifices on its straight portion, to facilitate the passage of the cooling fluid within the electrical conductor, in particular by avoiding the coil head where appropriate. In a configuration in which at least one end of the stator the coil heads and / or ends of the electrical conductors are immersed in a cooling fluid, the admission, passage and collection of the cooling fluid can thus be ensured by said at least two end orifices on either side of the stator mass, without requiring a major modification of the cooling circuit.

[0024] The electrical conductor according to the invention makes it possible to improve the cooling of the machine, by increasing the surface wetted by the cooling fluid, and by reducing the thermal resistance between the hot source constituted by the metal, in particular copper or aluminum, of the electrical conductor and the cooling fluid.

[0025] The invention finally makes it possible to simplify the implementation of cooling by eliminating the need for inlet and / or outlet manifolds for the cooling fluid and any connection parts. No additional modification to the cooling circuit is required.

[0026] The coolant can be a coolant, for example, cooling oil.

[0027] The electrical conductor may have a rectangular, square or circular cross-section, this list not being exhaustive.

[0028] The electrical conductor can be made of metal, particularly copper or aluminum.

[0029] The straight portion of the leg, in particular of each leg, may have in one embodiment two end orifices, located on either side of the stator mass.

[0030] The electrical conductor may be single-stranded. By "single-stranded" we mean that the conductor has only one strand.

[0031] By improving the cooling system, the invention simplifies the winding of the stator comprising the electrical conductors. The improved cooling limits the need to reduce the thickness of the electrical conductor to reduce eddy current losses, which makes it possible to reduce the critical height of the conductor and therefore to reduce the number of strands in parallel, or even to use a single-strand electrical conductor.

[0032] Reducing the height of the conductor makes it possible to reduce the height of the notch receiving the conductor and consequently the height of the corresponding teeth of the notch. There is therefore less iron used, which generates less “iron” losses. The cooling capacity using the electrical conductor according to the invention is such that the maximum tolerable current density can exceed 50 A / mm 2

[0033] Alternatively, the electrical conductor may be multi-stranded, i.e. comprise several strands, for example two or three strands. Each strand of the electrical conductor may be formed of a hollow wire configured to be traversed by the cooling fluid. The straight portion may have, for all the strands formed of a hollow wire, a plurality of orifices for the passage of the cooling fluid.

[0034] A strand can have a rectangular, square, or circular cross-section, but this list is not exhaustive.

[0035] Each strand, whether or not formed from a hollow wire, can have a surface cross-section of between 4 mm 2 and 16 mm 2 , or even between 5 mm 2 and 15 mm 2 , better between 6 mm 2 and 13 mm 2 , or even between 7 mm 2 and 12 mm 2 .

[0036] Each strand formed from a hollow wire may provide a passage for the cooling fluid, the passage having a surface cross-section of between 1 mm 2 and 8 mm 2 , or even between 1.5 mm 2 and 7.5 mm 2 , better between 2 mm 2 and 6.5 mm 2 , or even between 3 mm 2 and 4 mm 2 .

[0037] A ratio between the surface S pof a cross-section of cooling fluid passage provided in a strand formed of a hollow wire and the surface area S of a cross-section of the strand may be between 0.2 and 0.5, or even between 0.3 and 0.4, being for example of the order of 0.38.

[0038] Each through-hole of a leg may be located on a surface of a strand of the electrical conductor extending radially or circumferentially relative to the Y axis of the leg.

[0039] The surface of the strand extending radially relative to the Y axis of the leg may be intended to be arranged parallel to the side of the notch into which the straight portion of the leg extends. This makes it easier to access the passage orifice. Furthermore, said surface may have the largest surface area available among the surfaces of the strand to provide said orifice.

[0040] The holes may be made by machining, laser cutting, drilling or punching, this list is not exhaustive. The holes may be through holes. A hole may pass through one surface of the strand, in particular a single surface of the strand. Alternatively, a hole may pass through two parallel surfaces of a strand, in particular two opposite surfaces.

[0041] The orifices may be circular, oval, polygonal, in particular rectangular, square, triangular, with or without rounded edges, this list not being exhaustive. The conductor orifices may all be of the same shape. Alternatively, at least one orifice may be of a different shape.

[0042] At least one cooling fluid passage orifice may have a height h of between 1 / 3 and 1 time the height H of the strand in which the orifice is hollowed out.

[0043] By "height" is meant a dimension of a strand or an orifice measured radially with respect to the longitudinal axis X of the stator.

[0044] The height h of a cooling fluid passage orifice can be between 0.45 mm and 7 mm, or even between 0.6 mm and 6 mm, better between 0.67 mm and 5 mm.

[0045] The height H of a strand can be between 1.3 mm and 7 mm, or even between 1.8 mm and 6 mm, or better between 2 mm and 5 mm.

[0046] All the holes in the electrical conductor may have a passage section of the same area. Alternatively, at least one hole may have a passage section of different area. The passage section of an orifice extends in a radial plane relative to the longitudinal axis X of the stator.

[0047] Each end hole i may be intended to be located at a distance d, from the stator mass, the distance di being between 1.8 mm and 6 mm, better between 2 mm and 5 mm. The distance di is the smallest distance between one end of the hole on the stator mass side and a point on the stator mass. The distance di may vary according to the end holes.

[0048] The leg, in particular each leg, may comprise an inclined portion between its straight portion and the coil head or the ends of the electrical conductors. Each end orifice i may be located at a distance Di from the inclined portion greater than 0.5 mm, better still greater than 0.7 mm, even better still greater than 1 mm. The distance Di is the smallest distance between one end of the orifice on the bending side and a point of the inclined portion. The distance Di may vary according to the end orifices. The plurality of orifices may comprise at least one secondary orifice intended to be arranged within the stator mass, in particular in the middle thereof. In one embodiment, the plurality of orifices comprises a single secondary orifice, in particular arranged in the middle of the stator mass. As a variant, the plurality of orifices comprises several secondary orifices, in particular two or three.

[0049] The strand formed from a hollow wire may have at least one groove, the groove extending parallel to the Y axis of the leg. The strand formed from a hollow wire may have a single groove. Alternatively, it may have several grooves, for example two grooves. The two grooves may be arranged on either side of the strand, in particular on parallel faces of the strand.

[0050] The electrical conductor may also comprise, as a variant or additionally, a strand, hollow or not, having at least one groove, the groove extending parallel to the Y axis of the leg. This strand may have a single groove. Alternatively, it may have several grooves, for example two grooves. The two grooves may be arranged on either side of the strand, in particular on parallel faces of the strand.

[0051] The groove(s) may be arranged on a surface of the strand, hollow or not, extending radially relative to the Y axis of the leg. Alternatively or additionally, they may be arranged on a surface extending circumferentially relative to the Y axis of the leg.

[0052] The invention also relates, according to another of its aspects, independently or in combination with the above, to a stator of a rotating electrical machine, comprising a stator mass comprising notches, at least one electrical conductor as previously defined being received in at least one notch.

[0053] The rotating electrical machine can be radial flux or axial flux.

[0054] The stator may comprise a plurality of electrical conductors, in particular a plurality of electrical conductors as described above. Each notch may comprise several electrical conductors, for example two, three or four electrical conductors. In each notch, the electrical conductors of the stator may be stacked on top of each other radially relative to the Y axis of the leg. Each electrical conductor of the plurality of electrical conductors may have the same number of holes. Alternatively, at least one electrical conductor may have a different number of holes.

[0055] The holes in the electrical conductors may all be of the same shape. Alternatively, at least one electrical conductor may have holes of different shapes for at least one strand.

[0056] The secondary holes of the electrical conductors may be arranged at the same locations on each strand. All holes may be arranged at the same locations on each strand. Alternatively, the holes may be arranged at different locations on different strands.

[0057] The strands of electrical conductors may have the same number of grooves. The grooves may be arranged similarly on each strand.

[0058] At least two consecutive strands may be arranged so that two of their grooves face each other. "Consecutive strands" means two strands stacked on top of each other. Consecutive strands may belong to the same conductor or to different conductors.

[0059] The stator slots can be configured to carry a cooling fluid. The presence of grooves, particularly two facing grooves, can help facilitate the passage of the cooling fluid through the slot. Additional circulation of cooling fluid through the slots increases the contact surface with the metal of the electrical conductors and can reduce pressure losses.

[0060] In one embodiment, the stator of a rotating electrical machine comprises a stator mass comprising a stator yoke and notches, at least one electrical conductor whose plurality of orifices comprises at least one secondary orifice intended to be arranged within the stator mass, in particular in the middle thereof, being received in the notches. The stator comprises at least one radial channel, configured to be traversed by the cooling fluid, passing at least in part through the stator yoke to at least one notch, so as to allow the circulation of the cooling fluid between the radial channel and at least one secondary orifice of at least one electrical conductor

[0061] By "radial channel" is meant a channel extending radially relative to the Y axis of the leg. The presence of a radial channel allows the fluid to arrive through the stator mass, in particular through its middle depending on the placement of the secondary orifices. A secondary orifice can thus constitute an entry point for the cooling fluid into the electrical conductor. The cooling fluid can flow axially along the Y axis of the leg on either side of a secondary orifice. In this embodiment, each end orifice can constitute an outlet for the cooling fluid from the electrical conductor.

[0062] The stator may have a single or multiple radial channels, including as many as secondary orifices.

[0063] In one embodiment, the plurality of ports of each conductor comprises a single secondary port intended to be disposed in the middle of the stator mass and the stator comprises a single radial channel, disposed in the middle of the stator mass.

[0064] The radial channel(s) open into a corresponding notch through an opening in the notch on the yoke side. Said opening may extend over a length of between 1 mm and 5 mm, for example approximately 3 mm, measured along the longitudinal axis X. When the stator mass is formed from a plurality of layers of laminations, the openings in the notches on the yoke side may extend over approximately 3 to 20 laminations.

[0065] Preferably, each secondary orifice has the same coordinate as an opening of at least one notch on the Y axis of the leg. This arrangement facilitates the circulation of the cooling fluid between a radial channel opening onto the opening and the secondary orifice.

[0066] The conductors received in a notch can be arranged such that their secondary orifices, and possibly all their other orifices, are positioned in the same coordinate on the Y axis of the leg. This arrangement of the conductors can ensure the circulation of the cooling fluid between each radial channel and at least one secondary orifice of several conductors.

[0067] In an embodiment where the conductor orifices pass through a single surface of a strand, two consecutive strands of a slot may be arranged so that their secondary orifices face different flanks of the slot. This alternating positioning of the secondary orifices in the slot helps to maximize fluid flow and achieve fluid balance.

[0068] Each notch may comprise two electrical conductors, in particular two single-strand electrical conductors. The improvement in cooling provided by the invention makes it possible to limit the number of strands of electrical conductors per notch to two strands, instead of four or six as is commonly encountered in the state of the art.

[0069] The cooling fluid can also circulate in the notch outside the conductors, particularly in grooves in the strands. This additional circulation increases the contact surface of the fluid with the metal, particularly copper, and can thus help reduce pressure losses.

[0070] The stator may have a single or multiple hoops or half-hoops. The hoops or half-hoops are used to delimit annular chambers around the coil heads and / or the ends of the electrical conductors, so as to isolate the electrical conductors from the rest of the machine, in particular from a rotor of the machine. The term "ends of the electrical conductors" refers to the free ends of the legs of the electrical conductors.

[0071] An annular chamber containing the coil heads and / or ends of the electrical conductors may be filled with a cooling fluid so that the coil heads and / or ends of the electrical conductors are immersed in it. Generally, the annular chambers may be filled with a cooling fluid, so as to act as cooling chambers.

[0072] The annular chamber(s) can be pressurized. The resulting increase in pressure in the stator increases the threshold for partial discharges and therefore the durability of the insulation system. This is particularly advantageous during voltage increases, for example, at 800 V instead of the usual 400 V.

[0073] The stator may have a through-shell extending the entire length of the stator and beyond the stator mass to separate the electrical conductors from the bore of the stator intended to receive a rotor of the machine.

[0074] A through-fret can be used to delimit two annular chambers, one containing the coil heads of the electrical conductors and / or the ends of the electrical conductors and the other the opposite ends of the electrical conductors.

[0075] In one embodiment, the notches may be closed on the side of the stator bore intended to receive the rotor. In this embodiment, the stator may comprise at least one half-hoop, in particular two half-hoops, extending from the stator mass to separate the electrical conductors from the stator bore. The presence of closed notches on the side of the stator bore makes it possible to use half-hoops instead of a through-hoop, preventing the cooling fluid from reaching the rotor by flowing from the notches.

[0076] The stator may have two half-frets, each extending from each end of the stator mass.

[0077] Each half fret can create an annular chamber.

[0078] In an embodiment where the stator has only a single half-fret, the half-fret insulates the coil heads of the electrical conductors from the rest of the machine.

[0079] The stator mass may comprise at least one complementary channel extending parallel or circumferentially to the Y axis of the leg, configured to be traversed by a cooling fluid.

[0080] In an embodiment where the stator comprises at least one radial channel, at least one radial channel can open onto at least one complementary channel, so as to allow circulation of the cooling fluid between the radial channel and the complementary channel.

[0081] This or these additional channels improve the efficiency of stator cooling. The additional channel(s) may extend into the stator mass yoke.

[0082] In one embodiment, the stator comprises a plurality of electrical conductors. The electrical conductors are U-shaped. In this embodiment, the electrical conductors each comprise first and second legs, the first and second legs each comprising a straight portion extending rectilinearly in first and second slots respectively, each electrical conductor comprising a plurality of strands, the strands of the first leg of an electrical conductor being arranged in the first slot in a radially inverse order to the strands of the second leg of the same electrical conductor in the second slot.

[0083] The use of U-shaped electrical conductors advantageously makes it possible to obtain a high slot filling coefficient, and thus a reduction in Joule losses at low frequencies.

[0084] Furthermore, since each electrical conductor has several strands, there is a reduction in induced current losses, or AC Joule losses, which is particularly advantageous when the operating speed is high. This also facilitates heat transfer to the cold source.

[0085] Reversing the order of the strands of the first leg in the first notch, relative to the order of the strands of the second leg of the same electrical conductor in the second notch, also called "transposition", makes it possible to minimize the circulating currents between the strands of the same electrical conductor in each of the first and second notches.

[0086] The first and second notches may not be consecutive. We can speak respectively of a forward notch and a return notch.

[0087] The first and second notches may be separated by a number of notches between 3 and 20, better between 6 and 16, being for example 7 or 8, or 10 or 11 notches.

[0088] In one embodiment, each slot may accommodate a single electrical conductor. In this case, the electrical conductors form a whole, not a fractional, coil.

[0089] Alternatively, each notch may accommodate at least a first and a second electrical conductor, the first leg of the first electrical conductor being disposed radially in the first notch in a first layer at a first radial position, and the second leg of the same first electrical conductor being disposed radially in the second notch in a second layer at a second radial position different from the first radial position.

[0090] In one embodiment, each notch houses a first and a second electrical conductor, on two layers. In this case, there can be both an inversion of the order of the strands of the same electrical conductor, and a change of layer between the first and second legs of the electrical conductor.

[0091] In one embodiment, each notch can accommodate two layers of two electrical conductors each, i.e. four electrical conductors distributed over two layers. In this case, there can be both an inversion of the order of the strands of the same electrical conductor, and a change of layer between the first and second legs of the electrical conductor. There can also be a permutation of the relative position of the two electrical conductors of the same layer between them, between the first and second notches, or on the contrary an absence of change in their relative position.

[0092] Each notch can accommodate two layers of two electrical conductors each, the relative positions of the two electrical conductors of the same layer being swapped between the first and second notches.

[0093] At least one first electrical conductor housed in a first notch can be electrically connected to a second electrical conductor housed in a second notch, at the outlet of said notches. The electrical conductors can be connected by a single weld extending radially relative to a longitudinal axis X of the stator.

[0094] The invention also relates, according to another of its aspects, independently or in combination with the above, to a rotating electrical machine comprising a stator as previously defined. The machine may comprise a rotor, which may be placed in the bore of the stator.

[0095] The rotating electrical machine can be radial flux or axial flux.

[0096] In an embodiment where the stator of the rotating electrical machine comprises at least one half-fret or one fret creating at least one annular chamber, the casing may have at least one opening allowing fluid communication between the exterior of the casing and the annular chamber.

[0097] Brief description of the drawings

[0098] The invention may be better understood by reading the detailed description which follows, non-limiting examples of its implementation, and by examining the attached drawing in which:

[0099] [Fig 1] Figure 1 is a perspective view of several single-strand electrical conductors according to the invention.

[0100] [Fig 2] Figure 2 is a schematic, partial cross-sectional view of examples of stator slots in which two multi-strand electrical conductors are received.

[0101] [Fig 3] Figure 3 is a schematic and partial cross-sectional view of examples of stator slots in which two single-strand electrical conductors are received. [Fig 4] Figure 4 shows two longitudinal sections of two radial flux rotating electrical machines according to the invention, the stator of which has at least one half-hoop.

[0102] [Fig 5] Figure 5 shows two longitudinal sections of two radial flux rotating electrical machines according to the invention, comprising a stator comprising a radial channel and two half-frets.

[0103] [Fig 6] Figure 6 shows two longitudinal sections of two radial flux rotating electrical machines according to the invention, comprising a stator comprising a radial channel and without a half-fret or a fret.

[0104] [Fig 7] Figure 1 is a cross-section of a slot in a stator of a rotating electrical machine of Figures 5 or 6.

[0105] Detailed description

[0106] Figure 1 illustrates in isolation three electrical conductors according to the invention 1 folded in the shape of a U-shaped pin. The electrical conductors 1 are each intended to be received in a notch of a stator mass of a stator of a rotating electrical machine.

[0107] The electrical conductors 1 are single-stranded, that is to say that they each comprise a strand 2. Each strand 2 is formed of a hollow wire configured to be traversed by a cooling fluid. Each strand may have a surface cross-section S of approximately 12 mm 2 .

[0108] Each electrical conductor 1 comprises two legs 3 connected by a coil head 4. Each leg 3 comprises a straight portion 5 as well as an inclined portion 6 between the straight portion 5 and the coil head 4. The straight portion 5 has a plurality of orifices for the passage of the cooling fluid 7. Among the plurality of passage orifices 7, there are two end orifices 17 intended to be arranged on either side of the stator mass.

[0109] The passage holes 7 are circular in shape. All the passage holes 7 of the electrical conductors 1 have a passage section of the same surface area.

[0110] The end holes 17 are located at a distance Di? from the inclined portion 6, Di? is greater than 1 mm. The electrical conductors 1 can be made of copper or aluminum. The passage holes 7 can be made by machining.

[0111] Figures 2 and 3 each show five cross sections A, B, C, D, E of slots 8 of a stator, containing respectively two single-strand electrical conductors 1 and two single-strand electrical conductors 1. The slots 8 of Figure 2 thus comprise four strands 2 each, while the slots 8 of Figure 3 comprise two strands 2 each. All the strands 2 are formed of a hollow wire.

[0112] The straight portions 5 of the legs 3 of the electrical conductors 1 extend rectilinearly along an axis Y in the notches 8.

[0113] The electrical conductors 1 are stacked in the notches 8 on top of each other radially relative to axis Y of the leg. The notches 8 are configured to be traversed by a cooling fluid.

[0114] In the notch 8 of the sections A, the strands 2 have a rectangular cross-section with rounded edges. They do not have grooves. Each strand provides a passage for the cooling fluid 35. The passage 35 has a cross-sectional area Sp of approximately 2.5 mm 2 The ratio between the surface area Sp and the surface area S is approximately 0.5.

[0115] In the notch 8 of the sections B, the strands 2 have two grooves 9 arranged on either side of the strand, on parallel faces 10 of the strand. These faces 10 extend radially relative to axis Y of the leg.

[0116] In the notch 8 of the sections C, the strands 2 have two grooves 9 arranged on either side of the strand, on parallel faces 11 of the strand. These faces 11 extend circumferentially with respect to axis Y of the leg. All consecutive strands are arranged so that two of their grooves 9 face each other.

[0117] In the notch 8 of the sections D, the strands 2 have a single groove 9 arranged on a face 11 extending circumferentially relative to axis Y of the leg. Two consecutive strands of the same electrical conductor are arranged so that their two grooves 9 face each other.

[0118] In the notch 8 of the sections E, the strands 2 have a single groove 9 arranged on a face 11 extending circumferentially with respect to the longitudinal axis X. No groove 9 of a strand 2 faces a groove of a consecutive strand. Figure 4 shows two longitudinal sections of two rotating electrical machines 12. The rotating electrical machines 12 are radial flux.

[0119] Each rotating electrical machine 12 comprises a stator 13, extending along a longitudinal axis X, housed in a casing 14 and a rotor 15 housed in the bore 16 of the stator 13. The stator 13 comprises a stator mass 18 comprising notches 8. The straight portions 5 of the legs 3 of the electrical conductors 1 extend rectilinearly along an axis Y, in the notch 8 and at the outlets of the notch on either side of the stator mass 18. The axis Y of the leg, not shown in FIG. 4, is in this configuration parallel to the longitudinal axis X.

[0120] The notches 8 receive two electrical conductors 1 each comprising a single strand 2, stacked on top of each other radially relative to the Y axis of the leg.

[0121] The straight portion 5 of each leg 3 of each electrical conductor 1 comprises two cooling fluid passage orifices 7 which are end orifices 17 arranged on either side of the stator mass 18. The orifices 7, 17 are located on a face 19 of the strands 2 extending radially relative to the axis Y of the leg.

[0122] The passage holes 7, 17 have a height h corresponding to half the height H of the strands 2.

[0123] The end holes 17 are located at a distance di? from the stator mass 8 of approximately 2 mm.

[0124] In Figure 4 a), the stator 13 comprises two half-frets 21 and 22, which respectively delimit annular chambers 23 and 24. The annular chamber 23 contains the coil heads of the electrical conductors 1 and the annular chamber 24 contains the ends of the electrical conductors. Openings 25 and 26 in the casing 14 allow fluid communication from the outside of the casing with the annular chambers 23 and 24 respectively.

[0125] Arrows 20 indicate the direction of circulation of the cooling fluid in the casing 14, the cooling fluid entering the annular chamber 23 through the opening 25, entering through end orifices 17 in the electrical conductors, circulating axially in the electrical conductors, exiting through other end orifices 17 in the annular chamber 24 and exiting the casing through the opening 26.

[0126] In Figure 4 b), the rotating electrical machine 12 has only one half-fret 21 delimiting an annular chamber 23 around the coil heads of the electrical conductors 1. The fluid circulates similarly in Figure 4 a) except for its outlet, which is carried out by dripping towards the bottom of the casing 14.

[0127] Figure 5 a) illustrates a rotating electrical machine 12 comprising a rotor 15 and a stator 13, extending along a longitudinal axis X, housed in a casing 14. The stator 13 comprises a stator mass 18 comprising a stator yoke 27 and notches 8 in which electrical conductors 1 are housed. The plurality of passage orifices 7 of each electrical conductor 1 comprises a secondary orifice 28 arranged in the middle of the stator mass 18. The axis Y of the leg, not shown in Figure 5, is in this configuration parallel to the longitudinal axis X.

[0128] The stator 13 comprises radial channels 29, configured to be traversed by a cooling fluid, each radial channel 29 passing through the stator yoke 27 in its entirety up to a notch 8. A radial channel 29 opens onto a corresponding notch 8 via a notch opening 31 on the side of the stator yoke 27, as illustrated in FIG. 7.

[0129] As described with reference to Figure 4, the stator 13 comprises two half-frets 21 and 22, which create annular chambers 23 and 24 respectively. The annular chamber 23 contains the coil heads of the electrical conductors 1 and the annular chamber 24 contains the ends of the electrical conductors. Openings 25 and 26 in the casing 14 allow fluid communication from the outside of the casing with the annular chambers 23 and 24 respectively.

[0130] The electrical conductors 1 received in the notches 8 are arranged so that their secondary orifices 28 are positioned at the same coordinate ci on the Y axis of the leg and the longitudinal axis X.

[0131] Arrows 30 indicate the direction of circulation of the cooling fluid in the rotating electrical machine 12. The cooling fluid enters through the radial channel 29 passing through the casing 14, flows into the stator yoke 27 as far as the notch 8, enters the electrical conductors 1 through secondary orifices 28, circulates axially in the electrical conductors as far as end orifices 17 to open into the annular chambers 23 and 24 and leaves the casing through the openings 25 and 26.

[0132] The rotating electrical machine 12 of Figure 5 b) is identical to the rotating electrical machine of Figure 5 a) except for the stator mass 18 which additionally has complementary channels 32 extending parallel to the Y axis and the longitudinal X axis configured to be traversed by a cooling fluid. Each radial channel 29 can open onto an axial channel 32.

[0133] There can thus be fluid communication between the radial channels 29 and the axial channels 32 so that the cooling fluid can circulate in the radial channels 29 until it crosses a complementary channel 32 and uses this channel to arrive at the annular chambers 23 or 24.

[0134] Figures 6 a) and 6 b) show the configurations of the rotating electrical machines of Figures 5 a) and 5 b) without a half-hoop. The cooling fluid leaving the end orifices 17 flows towards the bottom of the casing 14.

[0135] Figure 7 shows in cross section a notch 8 of a stator mass of a stator of a rotating electrical machine as shown in Figures 5 and 6, the notch 8 comprising two single-strand conductors 1. A radial channel 29 opens onto the notch through a notch opening 31.

[0136] The secondary orifices 28 pass through a single face 10 of a strand 2, extending radially relative to the longitudinal axis X. The two strands 2 are arranged so that the secondary orifices 28 face different sides 33, 34 of the notch 8.

[0137] The invention is not limited to the exemplary embodiments presented.

[0138] The electrical conductors of Figure 2 may be single-strand conductors and thus the notches 8 of Figure 2 may receive four electrical conductors stacked on top of each other.

[0139] Rotating electrical machines can be radial flux.

[0140] The electrical conductors may be I-shaped. Alternatively, they may be wound to form a continuous wire coil.

[0141] The stator may alternatively have a through-ring.

[0142] The strands can have a different shaped cross-section.

[0143] The number of conductors in the slots, strands per conductor, radial channels, axial channels, through holes, grooves can vary, this list is not exhaustive.

Claims

Claims 1. Electrical conductor (1) intended to be received in a notch (8) of a stator mass (18) of a stator (13) of a rotating electrical machine (12), the stator mass comprising a plurality of notches for receiving a plurality of electrical conductors, the electrical conductor comprising one or more strands (2), at least one strand being formed of a hollow wire configured to be traversed by a cooling fluid, the electrical conductor comprising at least one leg (3), in particular two legs (3) connected by a coil head (4), the leg comprising a straight portion (5) intended to extend rectilinearly along an axis Y in the notch and at the outlets of the notch on either side of the stator mass,the straight portion having for at least one strand formed of a hollow wire a plurality of orifices for the passage of the cooling fluid (7), each passage orifice (7) of a leg (3) being located on a surface (10) of a strand (2) of the electrical conductor extending radially or circumferentially relative to the Y axis of the leg, the plurality of orifices comprising at least two end orifices (17) intended to be arranged on either side of the stator mass., 2. Electrical conductor (1) according to the preceding claim, being single-strand.

3. Electrical conductor (1) according to one of the preceding claims, a ratio between the surface S p of a cross-section of cooling fluid passage provided in a strand formed of a hollow wire and the surface area S of a cross-section of the strand being between 0.2 and 0.5, or even between 0.3 and 0.4, being for example of the order of 0.

38.

4. Electrical conductor (1) according to any one of the preceding claims, at least one cooling fluid passage orifice (7) having a height h of between 1 / 3 and 1 times the height H of the strand (2) in which the orifice is hollowed out.

5. Electrical conductor (1) according to any one of the preceding claims, each end orifice (17) being intended to be located at a distance di (dn) from the stator mass (18), the distance di being between 1.8 mm and 6 mm, better between 2 mm and 5 mm.

6. Electrical conductor (1) according to any one of the preceding claims, the leg (3) comprising an inclined portion (6) between its straight portion (3) and the coil head (4) or ends of the electrical conductors, each end orifice z (17) being located at a distance Di (DIT) from the inclined portion greater than 0.5 mm, better still greater than 0.7 mm, even better still greater than 1 mm.

7. Electrical conductor (1) according to any one of the preceding claims, the strand (2) formed from a hollow wire having at least one groove (9), the groove extending parallel to the Y axis of the leg.

8. Electrical conductor (1) according to any one of the preceding claims, the plurality of orifices (7) comprising at least one secondary orifice (28) intended to be arranged within the stator mass (18), in particular in the middle thereof.

9. Stator of a rotating electrical machine (13), comprising a stator mass (18) comprising notches (8), at least one electrical conductor (1) according to any one of the preceding claims being received in at least one notch.

10. Stator of a rotating electrical machine (13), comprising a stator mass (18) comprising a stator yoke (27) and notches (8), at least one electrical conductor (1) according to claim 8 being received in the notches, the stator comprising at least one radial channel (29), configured to be traversed by the cooling fluid, passing at least in part through the stator yoke to at least one notch, so as to allow the circulation of the cooling fluid between the radial channel and at least one secondary orifice of at least one electrical conductor.

11. Stator of a rotating electrical machine (13) according to one of claims 9 or 10, the notches (8) being closed on the side of the bore of the stator intended to receive the rotor (15), the stator comprising at least one half-hoop (21, 22), in particular two half-hoops, extending from the stator mass (18) to separate the electrical conductors (1) from the bore (16) of the stator.

12. Stator of a rotating electrical machine (13) according to any one of claims 9 to 11, the stator mass (18) comprising at least one complementary channel (32) extending parallel or circumferentially to the Y axis of the leg, configured to be traversed by a cooling fluid.

13. A rotating electrical machine stator (13) according to any one of claims 9 to 12, comprising a plurality of electrical conductors (1), the electrical conductors being U-shaped and each comprising first and second legs (3), the first and second legs (3) each comprising a straight portion (5) extending rectilinearly respectively in first and second notches (8), each electrical conductor comprising several strands (2), the strands of the first leg of an electrical conductor being arranged in the first notch in a radially inverse order to the strands of the second leg of the same electrical conductor in the second notch, at least one first electrical conductor housed in a first notch being electrically connected to a second electrical conductor housed in a second notch, at the outlet of said notches, in particular by a single weld extending radially relative to a longitudinal axis X of the stator.

14. Rotating electrical machine (12) comprising a stator (13) according to any one of claims 9 to 13.

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