Axial-flux electric machine and method for assembling such a machine

Abstract

The invention relates to an axial-flux electric machine (100) comprising: - a housing; first and second stators (40, 60) comprising first and second circular buses (30, 70) having conductive tracks (304, 306, 308, 704, 706, 708) on which are arranged connection terminals (3061, 3062, 7061, 7062) allowing connection to the coils of the stators (40, 60) and which are supplied by supply phases (U, V, W), the circular buses (30, 70) and the coils being interchangeable between stators; and indexing devices (2, 9) that position the circular buses (30, 70) in the housing, so as to place facing a connection terminal (3062) of the first circular bus (30) and a connection terminal (7061) of the second circular bus (70) that are supplied by a same supply phase (V).

Description

[0001] DESCRIPTION

[0002] Title of the invention: Axial flux electric machine and method of assembling such a machine

[0003] The present invention relates to the fields of electrical engineering and mechanics and more specifically concerns an axial flux electric machine.

[0004] Currently, electric or hybrid electric vehicles use electric traction or propulsion motors, which are often radial flux electric machines, that is to say that the stator windings of such a machine generate a magnetic flux in a radial direction relative to an axial direction corresponding to the axis of rotation of the machine.

[0005] In order to reduce the size of such a motor used for traction or propulsion of an electric vehicle, it is envisaged to use, instead of a radial flux electric machine, an axial flux electric machine. This type of machine is in fact generally more compact at least in one axial direction corresponding to the axis of rotation of the machine, which gives it a discoid appearance.

[0006] Some of these axial flux electric machines have an advantageous configuration, in particular double-stator axial flux electric machines comprising two wound stators, preferably three-phase, between which a rotor equipped with permanent magnets rotates. This type of machine makes it possible, at equivalent power, to reduce the radius of the axial flux electric machine compared to a single-stator machine. However, the manufacture and assembly of such a double-stator machine is complex and expensive, in particular due to the electrical connections to be made to the coils of each of the machine's stators. Indeed, on the two stators of the machine which are opposite each other, the coils facing each other must be powered by the same power supply phase, while being crossed by a current flowing through these coils in the same direction, so that they generate a magnetic flux of the same direction and in the same direction.These requirements make the coil connections a source of errors. Keying systems are therefore necessary for the assembly of the electric machine, on the one hand to correctly connect the coils of each stator to conductive buses each connected to a power supply phase of the electric machine, and on the other hand to electrically connect these conductive buses to a power electronics module (comprising an inverter) itself connected to a high-voltage battery of the vehicle. In particular, the winding direction on the machine coils is reversed from one stator to another, and the conductive buses connected to the machine coils have different configurations from one stator to another. These different parts for each stator and these keying systems make the manufacturing and assembly of the machine expensive.

[0007] The present invention at least partially overcomes the drawbacks of the prior art by providing a three-phase axial flux electric machine and a method of assembling such a machine, which reduce the diversity of parts used in manufacturing the machine and reduce the risk of error during assembly.

[0008] To this end, the present invention provides a three-phase axial flux electric machine comprising:

[0009] - a casing comprising a first portion housing a first stator and a second portion housing a second stator,

[0010] - a rotor capable of rotating around an axis of rotation, housed in the casing between the first stator and the second stator,

[0011] - the first stator and the second stator, each of which comprises coils and which respectively comprises a first and a second three-phase circular bus, the first and second circular buses each comprising conductive tracks on which terminals for connecting the coils are arranged,

[0012] - and at least a first, a second and a third power supply phase connection on the first and on the second stator, each electrically connected to one of the conductive tracks of the first and respectively of the second circular bus, and each intended to be supplied by respectively a first, a second and a third power supply phase at the output of at least one power electronics module, the electrical machine being characterized: - in that the first circular bus, the second circular bus and the coils of the first and of the second stator are structurally identical, and

[0013] - in that it further comprises at least one first device for indexing a position of the first circular bus in the first portion of the casing, and at least one second device for indexing a position of the second circular bus in the second portion of the casing, the first and second indexing devices being capable of positioning in the casing a predetermined connection terminal among the connection terminals of the first circular bus, electrically connected to the second phase connection of the first stator, opposite a predetermined connection terminal among the connection terminals of the second circular bus, electrically connected to the second phase connection of the second stator, the electrical connections of the first and third phase connections to the conductive tracks being reversed on the first stator relative to the second stator.

[0014] By "facing" or "face to face" or "opposite" in this application is meant radially and angularly at the same position, the radial and angular directions being defined relative to the same axial direction given by the axis of rotation of the rotor, even if intermediate parts separate the elements considered face to face.

[0015] The indexing devices are, for example, pins fixed to the circular buses and fitting into corresponding locations in each housing portion. They may alternatively be a mark on the predetermined terminal of each circular bus. The angular position of the indexing device on each circular bus is determined relative to the angular position of the predetermined connection terminal of the circular bus.

[0016] Thus, thanks to the invention, only the first indexing device and the second indexing device are necessary to avoid electrical connection errors when assembling the machine. Indeed, the first circular bus, the second circular bus and the coils of the first and second stators are structurally identical, which means that the circular buses and the coils are interchangeable from one stator to another. In particular, the coils on the first stator and the second stator have the same winding direction. This reduction in the diversity of parts allows for manufacturing savings and simplifies assembly.

[0017] It should be noted that in the invention, each circular bus comprises its conductive tracks and the terminals for connecting these conductive tracks to the coils of the stators. As a result, the circular buses are not symmetrical to each other, with respect to a plane orthogonal to the axis of rotation of the electrical machine, when the circular buses are housed in the casing of the machine. If this were the case, there would be no need to reverse the first and second phase connections on the two stators to operate the machine.

[0018] The invention also makes it possible to save a manufacturing mold for a second circular bus since the manufacturing mold of the first circular bus can be used to manufacture the second circular bus, and therefore to save a separate manufacturing line also for this second circular bus.

[0019] It should be noted that the second phase connection to which the predetermined connection terminals are connected is supplied by any supply phase but identical for both predetermined connection terminals, the important thing being the inversion of the other phase connections on the first stator with respect to the second stator, as will be described in the detailed description. In addition, the circular buses form structures angularly positioning the connection terminals of the coils, but these structures are not necessarily completely circular or closed.

[0020] According to an advantageous characteristic of the electrical machine according to the invention, the first indexing device is a first terminal block fixed to the first circular bus and capable of fitting into a dedicated location of the first housing portion, and the second indexing device is a second terminal block fixed to the second circular bus and capable of fitting into a dedicated location of the second housing portion, the first terminal block and the second terminal block comprising the first, second and third phase connection of the first circular bus and respectively of the second circular bus. Advantageously, the assembly of the first circular bus and first terminal block connected to each other forms a structure identical to that formed by the assembly of the second circular bus and second terminal block connected to each other. By structurally is meant that the mechanical parts are identical but their connections to the power supply phases may differ.The first and second terminal blocks are positioned, for example, in locations facing each other in the housing, and in the same way on each circular bus, structurally interchangeable from one stator to another, thanks to a judicious choice of predetermined connection terminals. This further avoids electrical connection errors.

[0021] In one embodiment of the electrical machine according to the invention, the coils of the first stator are connected in star, the coils of the second stator are connected in star, the connection terminals of the coils of the first and respectively of the second stator define, on a face of the first and respectively of the second circular bus having the connection terminals, the same sequence repeating in rotation according to a predefined angle in the clockwise direction, and the position of the predetermined connection terminal on the first circular bus and the position of the predetermined connection terminal on the second circular bus are identical in the sequence of connection terminals of the first and second circular buses. In other words, the predetermined connection terminal on one or other of the first and second circular buses is chosen from any one of the connection terminals connected to the second phase connection.

[0022] Preferably in this embodiment of the machine according to the invention, the second phase connection of the first terminal block is angularly located at the same position as the predetermined connection terminal of the first circular bus. Similarly, the second phase connection of the second terminal block is preferably angularly located at the same position as the predetermined connection terminal of the second circular bus. Thus, although the phase connections are reversed on the first terminal block and the second terminal block, it is sufficient to place the two terminal blocks exactly opposite each other, to correctly position the first stator and the second stator in the housing. Alternatively, in this embodiment of the invention, when the number of pole pairs of the electrical machine is odd, the second phase connection of the first hornier is angularly located at 180° relative to the predetermined connection terminal of the first circular bus.Preferably in this alternative, the second phase connection of the second hornier is located angularly at 180° relative to the predetermined connection terminal of the second circular bus, in order to have to place the first hornier exactly opposite the second hornier to properly position the first and second stators in the casing of the electric machine.

[0023] Finally, in this embodiment of the invention, the first circular bus and the second circular bus each preferably comprise a neutral point conductive track to which all the coils of the first stator and all the coils of the second stator are respectively connected.

[0024] In another embodiment of the invention, the coils of the first stator are connected in a triangle, the coils of the second stator are connected in a triangle, the connection terminals of the coils of the first and respectively of the second stator define, on a face of the first and respectively of the second circular bus having the connection terminals, the same sequence repeating in rotation according to a predefined angle in the clockwise direction, and the predetermined connection terminal on the first circular bus corresponds to the connection terminal immediately following the predetermined connection terminal on the second circular bus in the sequence of connection terminals of the first and second circular buses.

[0025] Preferably in this other embodiment of the invention, the second phase connection of the first terminal block is located angularly between two connection terminals of the first circular bus, electrically connected to the second phase connection of the first stator. Also preferably in this other embodiment of the invention, the second phase connection of the second terminal block is located angularly between two connection terminals of the second circular bus, electrically connected to the second phase connection of the second stator. Thus, the first and second indexing devices being positioned angularly between two successive connection terminals connected to the second phase connection on the first and respectively the second circular bus, it is sufficient to place the first hornier exactly opposite the second hornier to correctly position the first and second stators in the casing of the electrical machine.

[0026] Finally, depending on the star or delta connection of the coils of the electrical machine according to the invention, the angular position of the indexing device on each circular bus is for example determined relative to the angular position of a connection terminal of the circular bus, electrically connected to the second phase connection, or respectively relative to the angular positions of two successive connection terminals of the circular bus, electrically connected to the second phase connection. This makes it easy to place all the connection terminals connected to the second phase connection of the two circular buses face to face.

[0027] According to an advantageous characteristic of the electrical machine according to the invention, the conductive tracks of the first circular bus form an outer ring connected to the third phase connection, an intermediate ring surrounded by the outer ring and connected to the second phase connection, and an inner ring surrounded by the intermediate ring and connected to the first phase connection, while the conductive tracks of the second circular bus form an outer ring connected to the first phase connection, an intermediate ring surrounded by the outer ring and connected to the second phase connection, and an inner ring surrounded by the intermediate ring and connected to the third phase connection, the first, second and third phase connections of the first bus being placed respectively opposite the first, second and third phase connections of the second bus.

[0028] This axial symmetry of the phase connections of the two circular buses with respect to a plane orthogonal to the axis of rotation of the rotor makes it possible to further reduce the risks of connection errors. In addition, it makes it possible to electrically connect the phase connections to the power electronics module without crossing the electrical conductors providing these electrical connections. In order to further facilitate the production of these electrical connections, preferably the electrical machine according to the invention further comprises conductive bars electrically connecting the first, second and third phase connections of the first hornier to the first, second and third phase connections of the second hornier, respectively, the conductive bars each comprising an electrical connection terminal capable of receiving an electrical connection member to a power supply phase of said at least one power electronics module.

[0029] The invention also relates to a method of assembling a three-phase axial flux electric machine according to the invention, comprising the steps of:

[0030] - electrical connection of the first, second and third supply phase connections to the first circular bus,

[0031] - electrical connection of the first, second and third supply phase connections to the second circular bus,

[0032] - positioning the first circular bus in the first housing portion using the at least one first indexing device,

[0033] - positioning the second circular bus in the second housing portion using the at least one second indexing device,

[0034] - electrical connection of the coils of the first stator to the connection terminals of the first circular bus,

[0035] - electrical connection of the coils of the second stator to the connection terminals of the second circular bus,

[0036] - installation of the rotor,

[0037] - closing the casing.

[0038] Of course, these steps do not necessarily follow the order of this list. In particular, the electrical connection steps can be carried out before or after the electrical connection steps, especially when the indexing devices do not include phase connections. In addition, if the casing has two separate half-casings, each defining a portion of the casing housing one of the stators, the two half-casings having to be screwed to close the casing, then the rotor installation step is done after the circular bus positioning steps. In fact, in this case, the rotor is inserted between the two half-casings before screwing them in. On the contrary, if the casing is closed by a cover, the rotor can be installed before the positioning step of one of the circular buses.

[0039] When the indexing devices are the first and second terminal blocks, the steps of electrically connecting the first, second and third power supply phase connections to the first circular bus and to the second circular bus correspond to fixing the first terminal block on the first circular bus and to fixing the second terminal block on the second circular bus, and the steps of positioning the first circular bus in the first housing portion and of positioning the second circular bus in the second housing portion include positioning the first terminal block and respectively the second terminal block in a dedicated location of the first housing portion and respectively the second housing position.

[0040] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several examples of embodiment given for informational and non-limiting purposes with reference to the attached schematic drawings on the other hand, in which:

[0041] [fig 1] represents in perspective a three-phase axial flux electric machine according to the invention, in a first embodiment of the invention,

[0042] [fig 2] represents in perspective a first circular bus of the electrical machine of figure 1, so as to make visible a face of the first circular bus comprising coil connection terminals,

[0043] [fig 3] represents in perspective the first circular bus of figure 2, showing a face opposite the face containing the coil connection terminals,

[0044] [fig 4] schematically illustrates stators of the electric machine of figure 1, in which the coils are connected in star and in which terminal blocks having phase connections are located opposite each other when the stators are mounted in the electric machine, [fig 5] schematically illustrates alternative embodiments of figure 4, in which the terminal blocks having the phase connections are angularly located at a predetermined angle to each other when the stators are mounted in the electric machine, [fig 6] schematically illustrates other alternative embodiments of figure 4, in which the terminal blocks having the phase connections are angularly located at any angle to each other when the stators are mounted in the electric machine,

[0045] [fig 7] schematically illustrates an alternative embodiment of figure 4, in which the terminal blocks comprising the phase connections are located angularly opposite the terminal blocks of figure 4,

[0046] [fig 8] schematically illustrates stators of an electrical machine according to the invention, in a second embodiment of the invention, in which the coils of the machine are connected in a delta, and

[0047] [fig 9] represents steps of a method of assembling an electrical machine according to the invention.

[0048] According to a first embodiment of the invention shown in Figure 1, a three-phase axial flux electrical machine 1 comprises a first stator 4 and a second stator 6. Each stator 4, 6 is of substantially circular shape and centered around an axis of rotation X of a rotor (not shown), provided with permanent magnets and housed between the two stators 4, 6. In this application, the axis of rotation X defines an axial direction, a radial direction being orthogonal to this axial direction and passing through a radius of the rotor. An angular position in this application is defined in degrees on a circle centered on the axis of rotation X and included in a plane orthogonal to the axial direction.

[0049] Each stator 4, 6 comprises a plurality of coils 8 fixed on a yoke made of magnetic steel. The coils 8 of the second stator 6 are thus fixed on the yoke referenced 62 in FIG. 1. The coils 8 surround in a known manner stator teeth made of magnetic steel extending axially on the yoke of each stator 4, 6. More precisely, the copper wire of each coil 8 is wound on an electrically insulating winding support, for example made of synthetic polymer material, which is then fitted onto a stator tooth. Of course, other embodiments of the coils and their attachment to the stators are conceivable.

[0050] In a known manner, each coil 8 is intended to conduct an electric current of a first, second or third supply phase respectively U, V, or W at the output of a power electronics module (not shown) providing a three-phase current. Thus when the electrical machine 1 is supplied with current, the first stator 4 angularly comprises a repetition of a series of three coils supplied by the first, second and third supply phases U, V, W, i.e. five pairs of stator poles (fifteen coils 8 in total). The second stator 6 also comprises five pairs of poles, each coil 8 supplied by a supply phase U, V or W facing a coil 8 of the first stator 4 supplied by the same supply phase.

[0051] As visible in Figure 2, the electrical connection of the coils 8 of each stator 4, 6 to the supply phases U, V, W is made via a three-phase circular bus, the first three-phase circular bus 3 shown in Figure 2 being that of the first stator 4. The second three-phase circular bus 7 of the second stator 6 is referenced in Figures 4, 5 and 6 and is structurally identical to the first circular bus 3, which will therefore be the only one detailed in relation to Figures 2 and 3.

[0052] In this first embodiment of the invention, the coils 8 of the electrical machine 1 are connected in a star configuration. The first circular bus 3 therefore comprises four conductive tracks 32, 34, 36 and 38 which are non-closed circular conductive bars, having the shape of non-closed cylindrical rings. The conductive track 32 is central and corresponds to a neutral point of the stator 4.

[0053] The conductive track 34 corresponds to an internal cylindrical ring surrounding the central conductive track 32, and is electrically connected to a first phase connection 28 intended to be connected to the first power supply phase U. The conductive track 36 corresponds to an intermediate cylindrical ring surrounding the conductive track 34, and is electrically connected to a second phase connection 26 intended to be connected to the second power supply phase V.

[0054] The conductive track 38 corresponds to an external cylindrical ring surrounding the conductive track 36, and is electrically connected to a third phase connection 24 intended to be connected to the third power supply phase W.

[0055] Alternatively, other arrangements of the conductive tracks are of course conceivable. In particular, the conductive tracks are not nested together but arranged radially at the same level. They can also take a shape other than a cylindrical ring, for example a wire-like shape forming a polygon.

[0056] On the face 31 of the first circular bus 3 visible in figure 2, connection terminals to the coils 8 are regularly distributed angularly on the conductive tracks 32 to 38 of the first circular bus 3. The ends of the wire of each coil 8 are shown clipped into these connection terminals. Of course, other types of attachment to these connection terminals are possible, for example by laser welding or brazing. The longer ends are attached to the central conductive track 32 of neutral point.

[0057] In the electrical machine 1, according to the invention, the winding direction of the copper wire on each coil 8 is identical from one coil to another, and the coils 8 are interchangeable from one stator to another. As a result, the coils 8 facing each other have axially a winding direction reversed with respect to each other, and are powered by an electric current evolving in the same direction as represented by the thick solid line arrows, that is to say generating a magnetic flux evolving in the same direction in the axial direction. The copper wire used is of round, square or rectangular section.

[0058] The repetition of the sequence of three coils 8 mentioned above results in a clockwise repetition h on the face 31, of a sequence of connection terminals 361, 321, 341, 322, 381 and 323 repeating every 72 degrees, i.e. 360 degrees divided by the number of pairs of poles of the electrical machine to generalize to any number of pairs of poles. The second, fourth and sixth connection terminals 321, 322 and 323 of this sequence of connection terminals belong to the central conductive track 32 of neutral point.

[0059] The first connection terminal 361 of the series of connection terminals belongs to the conductive track 36 electrically connected to the second phase connection 26, the third connection terminal 341 of the series of connection terminals belongs to the conductive track 34 electrically connected to the first phase connection 28 and the fifth connection terminal 381 of the series of connection terminals belongs to the conductive track 38 electrically connected to the third phase connection 24.

[0060] On the face 33 opposite the face 31 of the first circular bus 3, illustrated in Figure 3, it is visible that the phase connections 24, 26 and 28 are made in the form of metal cylinders. The non-visible base of each cylinder 24, 26, 28 is hollowed out to receive an axial extension 385, 365 or 345 of a respective conductive track 38, 36 or 34 welded into the hollow cylinder. These axial extensions extend angularly only along a portion of the base of the corresponding cylinder and are represented by dotted lines in Figure 3. Of course, as a variant, other types of fixing of the phase connections 24, 26 and 28 to the circular buses of the first stator 4 are conceivable.

[0061] The bases, visible face in Figure 3, of the cylinders corresponding to the phase connections 24, 26, 28, have threaded orifices respectively 242, 262 and 282 allowing their electrical connection to the free ends of conductive bars respectively 57, 55 and 53 of the first stator 4, visible in Figure 1, these free ends being arranged near the axis of rotation X of the rotor. Indeed in Figure 1, the first and second circular buses as well as their respective phase connections are not shown.

[0062] Phase connections 94, 96 and 98 of the second circular bus 7 shown in Figures 4 to 6 are symmetrically connected to the free ends of conductive bars 52, 54 and 56 respectively of the second stator 6, visible in Figure 1. Given the position of the free ends of the conductive bars 52 to 57 in Figure 1, it can be guessed that the circular buses 3, 7 are arranged on an internal radial periphery of the coils 8, around a hub of the rotor. In a variant, the circular buses of the electrical machine according to the invention are arranged on an external radial periphery of the coils 8. In another variant, the conductive tracks of the circular buses of the electrical machine according to the invention are axially offset from each other while being radially arranged at the same level.

[0063] The other ends of the conductive bars 53, 55, 57 of the first stator 4 comprise respective electrical connection terminals 531, 551, 571 in the form of eyelets, these electrical connection terminals being superimposed on respective electrical connection terminals 521, 541, 561, also in the form of eyelets and arranged at the other ends of the respective conductive bars 52, 54, 56 of the second stator 6. These six electrical connection terminals 521, 531, 541, 551, 561, 571 superimposed two by two make it possible to receive three electrical connection members to the power electronics module, each electrical connection member ensuring the electrical connection of the first and second stators 4, 6 to a power supply phase U, V or W at the output of the power electronics module.

[0064] In order to mount the first stator 4 opposite the second stator 6 in the electrical machine 1, so that the coils 8 facing each other are powered by the same phase and carried by a current flowing in the same direction, the first stator 4 is housed in a first portion of a casing 12 of the electrical machine 1, being positioned angularly by means of a first indexing device. The casing 12 takes a generally cylindrical shape, the bases of this cylindrical shape corresponding to walls of the casing 12 which each comprise a central hole 122 allowing a rotor shaft to pass through.

[0065] Likewise, the second stator 6 is housed in a second portion of the casing 12 of the electrical machine 1, being positioned angularly using a second indexing device.

[0066] In this first embodiment of the invention, the first indexing device is a first terminal block 2 (referenced figures 4 to 6) comprising the phase connections 24, 26 and 28 of the first circular bus 3, and the second indexing device is a second terminal block 9 comprising the phase connections 94, 96 and 98 of the second circular bus 7. These first and second terminal blocks 2, 9 each form a block overmolded with their phase connections, this overmolding being made of an electrically insulating material. Other embodiments of the terminal blocks 2, 9 are of course conceivable.

[0067] The first terminal block 2 is inserted into a corresponding hole 124 (referenced in FIG. 3) in a wall of the casing 12, this hole allowing access to the threaded holes 242, 262 and 282 for screwing the respective conductive bars 57, 55 and 53 therein for connecting the first stator 4 to the power electronics module. Similarly, the second terminal block 9 is inserted into a corresponding hole 126 (referenced in FIG. 1) in a wall of the casing 12, this hole 126 allowing access to the threaded holes of the phase connections 94, 96, 98 for screwing the respective conductive bars 52, 54 and 56 therein for connecting the second stator 6 to the power electronics module.

[0068] Alternatively, the casing may not have holes for inserting the terminal blocks, in particular when their connection to the power electronics module is made by an outlet on an external radial periphery of the casing. In this case, it is necessary to ensure, for example, that the terminal blocks are located axially facing each other, for example visually, when this condition is sufficient to correctly position the connection terminals of the electrical machine angularly, in a manner similar to the example given in Figure 4.

[0069] In the exemplary embodiment of the first embodiment of the invention shown in Figure 4, the first and second stators 4, 6 are shown not mounted in the electrical machine 1, so as to visualize the faces of their respective circular buses 3, 7 which comprise the connection terminals to their coils 8. Only three coils 8 are shown on each stator 4, 6 for simplicity. The winding directions of the coils 8 are represented by thick, solid line arrows above the coils 8, the direction of current flow is represented by thick, solid line arrows in one of the coils 8 of each stator 4, 6. This figure 4 shows, on the first stator 4, the clockwise repetition h on the face 31, of the series of connection terminals 361, 321, 341, 322, 381 and 323 repeating every 72 degrees, this angle being referenced a in figure 4.

[0070] It should be noted that the invention can be generalized to an electrical machine having more than five pairs of poles by taking the angle a equal to 360 degrees divided by the number of pairs of poles of the electrical machine considered.

[0071] Similarly, on the second stator 6, a clockwise repetition h is shown on the face presenting the connection terminals of the second circular bus 7, of a series of connection terminals 761, 721, 741, 722, 781 and 723 repeating according to the angle a. This series of connection terminals is structurally identical to the series of connection terminals 361, 321, 341, 322, 381 and 323 of the first circular bus 3.

[0072] The assembly of the first circular bus 3 and the first terminal block 2 connected to each other forms a structure identical to that formed by the assembly of the second circular bus 7 and the second terminal block connected to each other. Only the power supplies of these assemblies differ.

[0073] Notably :

[0074] - the connection terminal 761 belongs to a conductive track 76 connected to the second phase connection 96 intended to be supplied by the second supply phase V of the power electronics module,

[0075] - the connection terminal 741 belongs to a conductive track 74 connected to the third phase connection 98 intended to be supplied by the third power supply phase W of the power electronics module,

[0076] - the connection terminal 781 belongs to a conductive track 78 connected to the first phase connection 94 intended to be supplied by the first supply phase U of the power electronics module,

[0077] - the connection terminals 721, 722, 723 belong to a neutral point conductive track 72. The second circular bus 7 is angularly rotated relative to the first circular bus 3, so that by axially positioning the first circular bus 3 facing the second circular bus 7, the line L extending over a radius of the circular bus 3 passing through the connection terminal 361, is axially symmetrical relative to a plane P orthogonal to the axis of rotation X of the electrical machine 1 and passing through the rotor, to a corresponding line L extending over a radius of the circular bus 7 and passing through the connection terminal 761. It should be noted, however, that the other connection terminals are generally not symmetrical to each other relative to the plane P.

[0078] The first phase connection 28 of the first stator 4 is positioned opposite the first phase connection 94 of the second stator 6, the second phase connection 26 of the first stator 4 is positioned opposite the second phase connection 96 of the second stator 6, and the third phase connection 24 of the first stator 4 is positioned opposite the third phase connection 98 of the second stator 6. This arrangement allows in particular the conductive bars 52, 53, 54, 55, 56, 57 not to cross and to be parallel to each other.

[0079] The terminal block and circular bus structures of the first and second stators 4, 6 being identical, this means that the outermost conductive track 38 of the first circular bus is connected to the third phase connection 24 connected to the third power supply phase W of the power electronics module, while the outermost conductive track 78 of the second circular bus is connected to the first phase connection 94 connected to the first power supply phase U of the power electronics module. This different electrical supply of the first stator 4 and the second stator 6 makes it possible, by positioning the first terminal block 2 opposite the second terminal block 9, to supply the coils facing each other with the same current generating a magnetic flux oriented in the same direction.The first terminal block 2 and the second terminal block 9 therefore serve as angular indexing devices for the first and second circular buses 3, 7 in the casing 12 of the electrical machine 1 by being positioned so that their respective second phase connections 26 and 96 are angularly positioned at the same location as the respective connection terminals 361 and 761, to which they are electrically connected.

[0080] In the embodiment variants of Figure 5, several possible positions for the second terminal block 9 are shown. This is angularly offset relative to the first terminal block 2 by an angle that is a multiple of a, in this case from 1 to 4 a in the clockwise direction h. This offset relates to an arrangement in which the circular buses 3, 7 of the electrical machine are mounted in the casing 12 and therefore facing each other. These variants are advantageous in the case where, for reasons of space, for example, the conductive bars 52, 54, 56 connected to the second terminal block 9 cannot be arranged axially symmetrically relative to the conductive bars 53, 55, 57 connected to the first terminal block 2. In this case, the holes 124, 126 of the first and second casing portions are angularly offset in the same way relative to each other, when the casing is closed.

[0081] In these variants, the second phase connections 26, 96 of the first and second terminal blocks being each angularly arranged at the same position as a connection terminal electrically connected to this second phase connection 26, 96, the connection terminal 361 connected to the second phase connection 26 of the first terminal block 2 remains facing the connection terminal 761 connected to the second phase connection 96 of the second terminal block 9. In these variants, the arrangement of the connection terminals of the circular buses 3, 7 remains the same as in FIG. 4 when the circular buses 3, 7 are facing each other.

[0082] In the embodiment variant shown in Figure 6, the second phase connection 26 of the first terminal block 2 is not angularly positioned at the same position as the connection terminal 361 connected to this second phase connection 26, but is angularly offset relative to this connection terminal 361, by any angle P in the clockwise direction h. In this case, the second terminal block 9 is angularly offset relative to the first terminal block 2 when they are mounted in the electrical machine 1, by an angle 2 P in the counterclockwise direction to within a multiple of the angle a. The angular position of the second terminal block 9 corresponding to a position opposite that of the first terminal block 2 is shown in dotted lines. This variant makes it possible to keep the properties of the electrical machine 1 according to the invention, namely that the connection terminals connected to the second phase connection 26, 96 of each stator 4, 6 are located opposite each other in the electrical machine 1.

[0083] In another embodiment variant shown in Figure 7, the second phase connection 26 of the first terminal block 2 is not angularly positioned at the same position as the connection terminal 361 connected to this second phase connection 26, but is angularly offset relative to this connection terminal 361, by an angle of 180°. The second phase connection 96 of the second terminal block 9 is, in this variant, positioned in the same way at 180° from the connection terminal 761 connected to the second phase connection 96 and facing the connection terminal 361. This arrangement is possible in the case where the electrical machine 1 has an odd number of pole pairs.

[0084] Thus in this first embodiment of the invention, the structures of the first and second circular buses 3, 7 are identical, but one must be rotated relative to the other so as to position a connection terminal connected to the second phase connection 26 of the first circular bus 3 opposite a connection terminal connected to the second phase connection 96 of the second circular bus 7, to obtain a correct power supply to the coils 8 of the electrical machine 1.

[0085] In a second embodiment shown in Figure 8, a three-phase axial flux electrical machine 100 according to the invention comprises a first stator 40 comprising a first circular bus 30 and a plurality of coils 8, only some of which are shown for simplicity. Similarly, the electrical machine 100 comprises a second stator 60 comprising a second circular bus 70 and a plurality of coils 8, only some of which are shown for simplicity. The electrical machine 100 has many characteristics in common with the electrical machine 1, these characteristics are therefore not detailed again. In particular, the first terminal block 2 is reused to connect the first circular bus 30 to the power electronics module, and the second terminal block 9 is reused to connect the second circular bus 70 to the power electronics module.

[0086] The electric machine 100 differs from the electric machine 1 in that its coils are connected in a triangle. Thus the first circular bus 30 does not have a neutral point conductive track, but does have:

[0087] - a circular conductive track 304, electrically connected to the first phase connection 28 and intended to be connected to the first power supply phase U;

[0088] - a circular conductive track 306, electrically connected to the second phase connection 26, surrounding the previous conductive track 304 and intended to be connected to the second power supply phase V;

[0089] - a circular conductive track 308, electrically connected to the third phase connection 24, surrounding the previous conductive track 306 and intended to be connected to the third power supply phase W.

[0090] The first circular bus 30 comprises, on a face comprising connection terminals to the coils 8 of the first stator 40, a clockwise repetition h of a series of six connection terminals repeating every 72 degrees, i.e. 360 degrees divided by the number of pairs of poles of the electrical machine to generalize to any number of pairs of poles. The first two connection terminals 3061, 3062 of this series belong to the conductive track 306, the next two connection terminals belong to the conductive track 304 and the last two connection terminals of this series belong to the conductive track 308.

[0091] The assembly of the first circular bus 30 and the first terminal block 2 connected to each other forms a structure identical to that formed by the assembly of the second circular bus 70 and the second terminal block 9 connected to each other. Only the power supplies of these assemblies differ.

[0092] Notably :

[0093] - two first connection terminals 7061, 7062 of a series of connection terminals identical to the series mentioned above belong to a conductive track 706 connected to the second phase connection 96 and intended to be supplied by the second supply phase V of the power electronics module,

[0094] - the two following connection terminals of this sequence belong to a conductive track 704 connected to the third phase connection 98 and intended to be supplied by the third power supply phase W of the power electronics module,

[0095] - and the last two connection terminals of this sequence belong to a conductive track 708 connected to the first phase connection 94 and intended to be supplied by the first power supply phase U of the power electronics module.

[0096] The conductive track 708 connected to the first phase connection 94 surrounds the conductive track 706 connected to the second phase connection 96, the latter conductive track 706 surrounding the conductive track 704 connected to the third phase connection 98. This arrangement makes it possible to arrange the first, second and third phase connections 28, 26, 24 of the first hornier 2 facing the first, second and third phase connections 94, 96, 98 of the second hornier 9 to facilitate their connection to the power electronics module, as in the first embodiment of the invention.

[0097] In this second embodiment of the invention, the second phase connection 26 of the first hornier 2 is located angularly between the two first connection terminals 3061 and 3062 electrically connected to this second phase connection 26, on the first circular bus 30. Similarly, the second phase connection 96 of the second hornier 9 is located angularly between the two first connection terminals 7061 and 7062 electrically connected to this second phase connection 96, on the circular bus 70.

[0098] Thus, by positioning the first hornier 2 facing the second hornier 9 during the assembly of the electrical machine 100, all the connection terminals of the first circular bus 30 connected to the second phase connection 26 are found facing connection terminals of the second circular bus 70 connected to the second phase connection 96, which allows the coils 8 facing each other to be supplied with the same current generating a magnetic flux oriented in the same direction. Alternative embodiments are possible by angularly offsetting the second terminal block 9 from the first terminal block 2, in particular by an angle that is a multiple of the angle a.

[0099] Thus in this second embodiment of the invention, the structures of the first and second circular buses 30, 70 are identical, but one must be rotated relative to the other so as to position two connection terminals connected to the second phase connection 26 of the first circular bus 30 opposite two connection terminals connected to the second phase connection 96 of the second circular bus 70, to obtain a correct power supply to the coils 8 of the electrical machine 1.This also amounts to positioning the connection terminal 3061 opposite the connection terminal 7062, which means that we can have an indexing device on the first circular bus aimed more specifically at positioning, in the connection sequence of the first circular bus structurally identical to the connection sequence of the second circular bus, the first connection terminal of the sequence of the first circular bus connected to the second phase connection, opposite the second connection terminal of the sequence of the second circular bus connected to the second phase connection.

[0100] A method of assembling the electrical machine 1 or 100 according to the invention is now described in relation to figure 9.

[0101] It is assumed, in the first and second embodiments of the invention, that the casing 12 is made of two half-casings each comprising the first or second stator, the two half-casings having to be screwed to each other by gripping the rotor in pincers to close the casing 12.

[0102] A first step 200 of the method is the electrical connection of the first, second and third power supply phase connections 28, 26, 24 to the first circular bus 3 or 30. This step is done by welding the cylinders constituting the phase connections 28, 26, 24 to the conductive tracks respectively 34, 36, 38 or 304, 306, 308. The second phase connection 26 is angularly positioned at the same position as the connection terminal 361 to which it is electrically connected in the first embodiment, or between the connection terminals 3061, 3062 to which it is electrically connected in the second embodiment. A second step 400 of the method is the electrical connection of the first, second and third power supply phase connections 94, 96, 98 to the second circular bus 7 or 70. This step 400 is carried out in a similar manner to step 200, the structures of the first and second circular buses being identical.

[0103] A third step 600 of the method is the positioning of the first circular bus 3 or 30 in the first portion of the casing by inserting the first terminal block 2 into the hole 124 of this first portion of the casing,

[0104] A fourth step 800 is the positioning of the second circular bus 7 or 70 in the second portion of the casing by inserting the second terminal block 9 into the hole 126 of this second portion of the casing,

[0105] A fifth step 1000 is the electrical connection of the coils 8 of the first stator 4 or 40 to the connection terminals of the first circular bus 3 or 30, by crimping each end of coil 8 angularly arranged at the same position as a connection terminal of the first circular bus 3 or 30, into this connection terminal. This step comprises the fixing of the stator yoke of the stator 4 or 40, on which the coils 8 of the stator 4 or 40 are mounted, to the half-casing housing the stator 4 or 40.

[0106] A sixth step 1200 is the electrical connection of the coils 8 of the second stator 6 or 60 to the connection terminals of the second circular bus 7 or 70, by crimping each end of coil 8 angularly arranged at the same position as a connection terminal of the second circular bus 7 or 70, into this connection terminal. This step comprises the fixing of the stator yoke of the stator 6 or 60, on which the coils 8 of the stator 6 or 60 are mounted, to the half-casing housing the stator 6 or 60.

[0107] It should be noted that the stator yokes are fixed in the half-casings so that the stator teeth are facing each other when the casing 12 is mounted. For this purpose, the half-casings have, for example, a marking allowing the stator teeth to be angularly positioned, regardless of each other. The position of the stator teeth also determines the position of the coils 8, regardless of each other, relative to the holes 124, 126 intended to receive the first and second terminal blocks 2, 9. Indeed, for example, in the diagram of FIG. 4, the stator teeth are arranged angularly so that the first and second phase connections of each hornier are connected to the same coil 8.

[0108] A seventh step 1400 is the positioning of the rotor between the two stators 4, 40 and 6, 60, in particular by positioning the rotor shaft in the passage orifices 122 provided for this purpose.

[0109] Finally, the last step 1600 is the closing of the casing 12 by screwing the two half-casings together.

[0110] The order of these steps is not fixed, and can be modified in variant embodiments of the assembly method according to the invention. In particular depending on the arrangement of the coil outputs relative to that of the circular buses, the fixing of the stator yokes in the half-casings can be carried out before the connection of the coils to the circular buses.

[0111] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention.

Claims

CLAIMS 1- Three-phase axial flux electric machine (1, 100) comprising: - a casing (12) comprising a first portion housing a first stator (4, 40) and a second portion housing a second stator (6, 60), - a rotor capable of rotating around an axis of rotation (X), housed in the casing (12) between the first stator (4, 40) and the second stator (6, 60), - the first stator (4, 40) and the second stator (6, 60), which each comprise coils (8) and which respectively comprise a first (3, 30) and a second three-phase circular bus (7, 70), the first and second circular buses each comprising conductive tracks (32, 34, 36, 38, 72, 74, 76, 78, 304, 306, 308, 704, 706, 708) on which connection terminals (361, 321, 341, 322, 381, 323, 761, 721, 741, 722, 781, 723, 3061, 3062, 7061, 7062) of the coils are arranged, - and at least a first, a second and a third power supply phase connections (28, 26, 24, 94, 96, 98) on the first and on the second stator (4, 40, 6, 60), each electrically connected to one of the conductive tracks (34, 36, 38, 74, 76, 78, 304, 306, 308, 704, 706, 708) of the first and respectively of the second circular bus (3, 30, 7, 70), and each intended to be supplied by respectively a first, a second and a third power supply phase (U, V, W) at the output of at least one power electronics module, the electrical machine (1, 100) being characterized: - in that the first circular bus (3, 30), the second circular bus (7, 70) and the coils (8) of the first and second stators (4, 40, 6, 60) are structurally identical, and - in that it further comprises at least one first indexing device (2) for a position of the first circular bus (3, 30) in the first portion of the casing, and at least one second indexing device (9) for a position of the second circular bus (7, 70) in the second portion of the casing, the first and second indexing devices (2, 9) being capable of positioning in the casing (12) a predetermined connection terminal (361, 3062) among the connection terminals (361, 321, 341, 322, 381, 323, 3061, 3062) of the first circular bus (3, 30), electrically connected to the second connection phase (26) of the first stator (4, 40), facing a predetermined connection terminal (761, 7061) among the connection terminals (761, 721, 741, 722, 781, 723, 7061, 7062) of the second circular bus (7, 70), electrically connected to the second phase connection (96) of the second stator (6, 60), the electrical connections of the first and third phase connections (28, 24, 94, 98) to the conductive tracks (34, 38, 78, 74, 304, 308, 708, 704) being reversed on the first stator (4, 40) with respect to the second stator (6, 60). 2- Electrical machine (1, 100) according to claim 1, wherein the first indexing device (2) is a first hornier fixed to the first circular bus (3, 30) and capable of fitting into a dedicated location (124) of the first housing portion, and the second indexing device (9) is a second hornier fixed to the second circular bus (7, 70) and capable of fitting into a dedicated location (126) of the second housing portion, the first terminal block and the second terminal block comprising the first, second and third phase connection (28, 26, 24, 94, 96, 98) of the first circular bus (3, 30) and respectively of the second circular bus (7, 70). 3- Electrical machine (1, 100) according to claim 2, in which the assembly of first circular bus (3, 30) and first terminal block (2) connected to each other forms a structure identical to that formed by the assembly of second circular bus (7, 70) and second terminal block (9) connected to each other. 4- Electrical machine (1) according to any one of claims 1 to 3, wherein the coils (8) of the first stator (4) are connected in star, the coils (8) of the second stator (6) are connected in star, wherein the connection terminals (361, 321, 341, 322, 381, 323, 761, 721, 741, 722, 781, 723) of the coils of the first (4) and respectively of the second stator (6) define, on a face (31) of the first (3) and respectively of the second circular bus (7) having the connection terminals, the same sequence repeating in rotation according to a predefined angle (a) in the clockwise direction (h), and wherein the position of the predetermined connection terminal (361) on the first circular bus (3) and the position of the predetermined connection terminal (761) Tl on the second circular bus (7) are identical in the sequence of connection terminals of the first and second circular buses (3, 7). 5- Electrical machine (1) according to any one of claims 2 to 4, wherein the coils (8) of the first and second stators (4, 6) are connected in star, and wherein the second phase connection (26) of the first hornier (2) is angularly located at the same position as the predetermined connection terminal (361) of the first circular bus (3). 6- Electrical machine (1) according to any one of claims 2 to 4, wherein the coils (8) of the first and second stators (4, 6) are connected in star, wherein the number of pole pairs of the electrical machine is odd and wherein the second phase connection (26) of the first hornier (2) is located angularly at 180° relative to the predetermined connection terminal (361) of the first circular bus (3). 7- Electrical machine (1) according to any one of claims 1 to 6, in which the coils (8) of the first and second stator (4, 6) are connected in star and in which the first circular bus (3) and the second circular bus (7) each comprise a conductive track (32) of neutral point (N) to which all the coils (8) of the first stator (4) and all the coils (8) of the second stator (6) are respectively connected. 8- Electrical machine (100) according to any one of claims 1 to 3, wherein the coils (8) of the first stator (40) are connected in a triangle, the coils (8) of the second stator (60) are connected in a triangle, wherein the connection terminals (3061, 3062, 7061, 7062) of the coils of the first (40) and respectively of the second stator (60) define, on a face of the first (30) and respectively of the second circular bus (70) having the connection terminals, the same sequence repeating in rotation according to a predefined angle (a) in the clockwise direction (h), and wherein the predetermined connection terminal (3062) on the first circular bus (30) corresponds to the connection terminal immediately following the connection terminal predetermined (7061) on the second circular bus (70) in the series of connection terminals of the first and second circular buses (30, 70). 9- Electrical machine (100) according to claim 8 taken in dependence on claim 2, in which the second phase connection (26) of the first hornier (2) is located angularly between two connection terminals (3061, 3602) of the first circular bus (30), electrically connected to the second phase connection (26) of the first stator (40). 10- An electrical machine (1, 100) according to any one of claims 2 to 9, wherein the conductive tracks (38, 36, 34, 308, 306, 304) of the first circular bus (3) form an outer ring connected to the third phase connection (24), an intermediate ring surrounded by the outer ring and connected to the second phase connection (26), and an inner ring surrounded by the intermediate ring and connected to the first phase connection (28), while the conductive tracks (78, 76, 74, 708, 706, 704) of the second circular bus (7, 70) form an outer ring connected to the first phase connection (94), an intermediate ring surrounded by the outer ring and connected to the second phase connection (96), and an inner ring surrounded by the intermediate ring and connected to the third phase connection (98), the first, second and third phase connections (28, 26, 24) of the first hornier (2) being placed respectively facing the first,second and third phase connections (94, 96, 98) of the second hornier (9)., 11- Electrical machine (1, 100) according to claim 10, further comprising conductive bars (52, 53, 54, 55, 56, 57) electrically connecting the first, second and third phase connections (28, 26, 24) of the first hornier (2) to the first, second and third phase connections (94, 96, 98) of the second hornier (9) respectively, the conductive bars (52, 53, 54, 55, 56, 57) each comprising an electrical connection terminal (521, 531, 541, 551, 561, 571) capable of receive an electrical connection member to a power supply phase (U, V, W) of said at least one power electronics module. 12- Method for assembling a three-phase axial flux electrical machine (1, 100) according to any one of claims 1 to 11, comprising the steps of: - electrical connection (600) of the first, second and third supply phase connections (28, 26, 24) to the first circular bus (3, 30), - electrical connection (800) of the first, second and third power supply phase connections (94, 96, 98) to the second circular bus (7, 70), - positioning (1000) of the first circular bus (4, 40) in the first housing portion using the at least one first indexing device (2), - positioning (1400) of the second circular bus (6, 60) in the second housing portion using the at least one second indexing device (9), - electrical connection (200) of the coils (8) of the first stator (4, 40) to the connection terminals (361, 321, 341, 322, 381, 323, 3061, 3062) of the first circular bus (3, 30), - electrical connection (400) of the coils (8) of the second stator (6, 60) to the connection terminals (761, 721, 741, 722, 781, 723, 7061, 7062) of the second circular bus (7, 70), - installation (1200) of the rotor, - closing (1600) of the casing (12). 13- A method of assembling a three-phase axial flux electrical machine (1, 100) according to claim 12 taken in dependence on claim 2, wherein the steps of electrically connecting (600, 800) the first, second and third supply phase connections (28, 26, 24, 94, 96, 98) to the first circular bus (3, 30) and to the second circular bus (7, 70) correspond to the fixing of the first terminal block (2) on the first circular bus (3, 30) and to the fixing of the second terminal block (9) on the second circular bus (7, 70), and wherein the steps of positioning the first circular bus (3, 30) in the first housing portion and of positioning the second circular bus (7, 70) in the second housing portion include the positioning the first terminal block (2) and respectively the second terminal block (9) in a dedicated location (124, 126) of the first portion of the casing and respectively the second position of the casing.

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