Rotor for axial flux electric machine with radial arms and cooling channels in the radial arms

Abstract

The present invention relates to a rotor for an axial flux electric machine comprising a rotor disk made of metallic material and permanent magnets, the rotor disk comprising housings, preferably of substantially trapezoidal cross-section, distributed circumferentially within the rotor disk, the permanent magnets being positioned in said housings, the rotor disk comprising radial arms (17) separating said housings. Furthermore, the rotor disk comprises cooling channels (10) for the circulation of a fluid from the inside to the outside in the cooling channels (10), at least one radial arm (17) comprising a radial portion (11) of at least one cooling channel (10). The invention also relates to an electric machine with such a rotor. Figure 5 to be published

Description

Title of the invention: Rotor for axial flux electric machine with radial arms and cooling channels in the radial arms Technical field

[0001] The invention relates to the field of axial flux electrical machines and it relates more particularly to a rotor for this type of electrical machine.

[0002] This type of axial flux electric machine can notably find applications in electric or hybrid vehicles, such as cars, buses, trucks, construction machinery. This type of machine can also be used for stationary applications, such as industrial charging machines or electric generators. Prior art

[0003] In recent decades, the development of electrical machines has focused mainly on radial flux electrical machines.

[0004] Radial flux electrical machines generally comprise a coaxial rotor and stator, one surrounding the other. Thus, the magnetic flux can pass radially from the rotor to the stator and vice versa, via a radial air gap which is defined as the radial clearance between the rotor and the stator.

[0005] On the contrary, axial flux machines are characterized by at least one rotor and at least one stator which are arranged successively one behind the other in the axial direction (of the axis of rotation of the rotor), so that the path of the magnetic flux between the rotor and the stator is axial. In other words, the rotor and the stator face each other and are separated by an air gap of axial thickness (or axial clearance between the rotor and the stator).

[0006] The rotor of axial flux electrical machines with permanent magnets generally comprises permanent magnets bonded to the rotor yoke or inserted into a rotor body and in this case, the permanent magnets are separated by radial arms from the rotor body. The stator generally comprises a ferromagnetic stator body with or without teeth. The electrical winding in the stator slots can be distributed or concentric, that is to say that each winding then surrounds a tooth.

[0007] In the context of the development of high power and torque density machines for electric or hybrid traction, in particular for electric or hybrid vehicle applications, the topology of axial flux machines is positioned among those with the highest potential, in particular due to the high constraint axial size. Axial flux electric machines are also of interest for stationary applications as well as for wind turbine applications.

[0008] Generally, axial flux electric machines allow higher power and torque densities than radial flux electric machines.

[0009] This gain is generally achievable by increasing the number of pole pairs in the rotor, which increases the rotation frequency as well as the rotor losses (i.e. the losses in the magnets). In addition, the use of a tooth winding makes it possible to reduce the coil heads, but however increases the harmonic content in the air gap, causing the increase of losses in the stator iron and in the magnets.

[0010] As a result, axial flux machines tend to heat up more, and controlling heating and cooling is therefore an important issue for this type of machine.

[0011] Patent application US2020 / 274410 relates to the cooling of a rotor with magnets bonded to a rotor disc. Cooling channels are positioned in the rotor disc, behind the magnets. They are therefore far from the stator located between two rotors. The cooling channels therefore do not allow effective cooling of the stator.

[0012] The technical problem that we propose to solve consists of improving the cooling of the permanent magnets and the stator of the electric machine, while facilitating the implementation of this cooling. Summary of the invention

[0013] To meet these objectives, the invention relates to a rotor for an axial flux electrical machine comprising a rotor disc made of metallic material and permanent magnets, the rotor disc comprising housings, preferably of substantially trapezoidal section, distributed circumferentially within the rotor disc, the permanent magnets being positioned in the housings, the rotor disc comprising radial arms separating the housings. Furthermore, the rotor disc comprises cooling channels for circulating a fluid from the inside to the outside in the cooling channels. Furthermore, at least one radial arm comprises a radial portion of at least one cooling channel.

[0014] According to one configuration of the invention, the permanent magnets are magnets passing completely through the rotor disk or magnets glued to the rotor disk.

[0015] According to one aspect of the invention, the rotor disk comprises an inner ring and an outer ring connected to each other by said radial arms, each cooling channel comprising at least one inner portion in the inner ring and preferably an outer portion in the outer ring.

[0016] Advantageously, at least one of the at least one cooling channel comprises at least one radial outlet.

[0017] Advantageously, at least one of the at least one cooling channel comprises at least one axial outlet and / or at least one outlet inclined at a non-zero angle relative to the axial direction and relative to the radial direction.

[0018] Preferably, at least one of the cooling channels comprises two outlets, one outlet on each side of the rotor disc or a radial outlet and an axial or inclined outlet, or in which the different cooling channels each have an outlet, the outlets of the different cooling channels, in the circumferential direction, being successively and alternately directed to one side then to the other of the rotor disc.

[0019] Advantageously, at least one radial arm comprises radial portions of two cooling channels, each of the two cooling channels having a single outlet, preferably each outlet of these two cooling channels opening onto a separate side of the rotor disk.

[0020] The invention also relates to an axial flux electrical machine comprising at least one stator and at least one rotor according to one of the variants or combinations of variants described above and preferably comprising two rotors and one stator, or two stators and one rotor or two stators and two rotors.

[0021] Advantageously, at least one cooling channel comprises at least one outlet directed towards at least one stator of the electrical machine, and preferably, when the electrical machine comprises a stator on each side of a rotor, each cooling channel comprises two outlets, one directed towards one stator and the other directed towards the other stator or each rotor disc of the rotor comprises alternately in the circumferential direction cooling channels with outlets successively and alternately directed towards one stator then towards the other stator.

[0022] According to one configuration of the invention, the electrical machine comprises a casing, the at least one rotor and the at least one stator being positioned in the casing, and a fluid supply system comprising a conduit passing through the casing.

[0023] According to a variant of the invention, the supply system comprises a sealed chamber formed between the casing and the rotor disk, the sealed chamber being fluidically connected to the conduit, the inlet of the cooling channel being fluidically connected to said sealed chamber to convey the fluid from said sealed chamber to the cooling channel.

[0024] Preferably, the supply system comprises a means for extending the conduit towards the rotor disc so that the fluid arrives in the rotor disc, by gravity, in an annular enclosure of the rotor disc connected to the different inlets of the different cooling channels.

[0025] According to one aspect of the invention, the casing comprises at least one machining opposite the radial outlets to direct the flow of fluid leaving the rotor towards the at least one stator.

[0026] Advantageously, the electrical machine comprises a central shaft on which the rotor disc is fixed and each cooling channel has a substantially axial inlet connected to said supply system or a radial inlet so that the fluid arrives via said central shaft of the electrical machine.

[0027] Preferably, the electrical machine comprises a fluid collection system at the outlet of the rotor and preferably a fluid reservoir connected to the collection system, downstream of the collection system or integrated into the collection system in the direction of the fluid flow, for the circulation of the fluid in a closed loop and possibly a pump for conveying the fluid from the collection system to said fluid reservoir, the reservoir preferably being integrated into the casing.

[0028] The invention also relates to the use of the electric machine according to one of the variants or combinations of variants described above, in an electric or hybrid vehicle, or in a stationary application, such as an industrial charging machine, an electric generator or a wind turbine. List of figures

[0029] Other characteristics and advantages of the rotor and the electrical machine according to the invention will appear on reading the following description of non-limiting examples of embodiments, with reference to the figures appended and described below. [Fig 1]

[0030] [Fig. 1] represents an example of an axial flux electric machine with a rotor and two stators according to the invention. [Fig 2]

[0031] [Fig.2] represents an example of an axial flux electric machine rotor according to the invention. [Fig 3]

[0032] [Fig. 3] represents a first embodiment of an axial flux electric machine rotor according to the invention. [Fig 4]

[0033] [Fig.4] represents a second embodiment of an axial flux electric machine rotor according to the invention. [Fig 5]

[0034] [Fig.5] represents a first variant of an axial flux electric machine rotor according to the invention. [Fig 6]

[0035] [Fig.6] represents a second variant of an axial flux electric machine rotor according to the invention. [Fig 7]

[0036] [Fig.7] represents a third variant of an axial flux electric machine rotor according to the invention. [Fig 8]

[0037] [Fig.8] represents a fourth variant of an axial flux electric machine rotor according to the invention. [Fig 9]

[0038] [Fig.9] represents a fifth variant of an axial flux electric machine rotor according to the invention. [Fig 10]

[0039] [Fig. 10] represents a first embodiment of a power supply system for an axial flux electric machine rotor according to the invention. [Fig 11]

[0040] [Fig. 11] represents a second embodiment of a power supply system for a rotor of an axial flux electric machine according to the invention. [Fig 12]

[0041] [Fig. 12] shows another configuration of the axial flux electric machine according to the invention with a closed loop cooling circuit. [Fig 13]

[0042] [Fig. 13] illustrates an embodiment of an axial flux electric machine according to the invention. [Fig 14]

[0043] [Fig. 14] illustrates a sixth variant of an axial flux electric machine rotor according to the invention. Description of the embodiments

[0044] The terms “vertical”, “horizontal”, “upper”, “lower” are understood to refer to the electrical machine of the invention in operating conditions, “upper” and “lower” being relative to the vertical axis.

[0045] The “longitudinal” direction is the direction of the axis of the central shaft and the electric machine.

[0046] The invention relates to a rotor for an axial flux electrical machine comprising a rotor disc made of metallic material and permanent magnets. Thus, when the coils of the stator of the electrical machine are crossed by an electric current, an electromagnetic torque is produced and drives the rotor of the machine in rotation, thanks to the interaction between the stator field produced by the winding and the field rotor produced by permanent magnets. Conversely, when the rotor is rotated by any means of rotation (a rotating shaft for example), the permanent magnets induce a magnetomotive force in the stator coils. This allows the mechanical energy of the rotor to be transformed into electrical energy in the stator. Therefore, the electric machine can be used as an electric motor that transforms electricity into mechanical energy, or as an electric generator that transforms mechanical energy into electrical energy.

[0047] The rotor disk serves as a support for carrying permanent magnets and to do this, it comprises housings, preferably of substantially trapezoidal section (but any other shape of the housings is conceivable), distributed circumferentially within the rotor disk, the permanent magnets being positioned in the housings. The rotor disk comprises radial arms separating said housings from each other. Preferably, when the section of the housings is trapezoidal, the largest base of the trapezoid is on the external side of the rotor.

[0048] By radial arms is meant spokes or portions located between the housings, these spokes or portions extending radially or substantially radially (i.e. substantially from an internal point to an external point) from an internal end to an external end.

[0049] For example, the rotor disk may be composed of an inner ring (or central hub) intended to be mounted on a shaft, an outer ring (or outer hoop) and radial arms which form the connection between the inner ring and the outer ring and which leave the space necessary for the introduction of the permanent magnets. The spaces located between the radial arms (and limited by the inner and outer rings) thus form the housings.

[0050] Advantageously, the housings can axially pass through the rotor disk to open at the two axial ends of the rotor disk. Thus, the permanent magnets can pass through the rotor disk axially on each side. This configuration is particularly advantageous when the electrical machine comprises a rotor and two stators, each stator being on either side of the rotor disk. This type of machine comprising a rotor and two stators, one stator on either side of the rotor, with the permanent magnets passing completely through the rotor disk is called a "through-permanent magnet electrical machine".

[0051] The rotor disc may for example have an annular shape between a cylindrical surface of internal diameter and a cylindrical surface of external diameter. In addition, it may have an axial external thickness (i.e. the axial length of the rotor disc, taken at its external surface) at its cylindrical external surface.

[0052] In addition, the rotor disc comprises cooling channels for the cir- culation of a fluid from the inside to the outside in the cooling channels. Thus, the cooling circuit does not require a return of the fluid from the outside to the inside, which would be difficult to achieve, given the centrifugal forces.

[0053] The fluid may be liquid or gaseous or multiphase. The fluid may advantageously be a liquid and more particularly cooling oil. For example, the fluid may be water, glycolated water or oil. In the case of direct contact of the fluid with the winding, it is preferable for the fluid to be a dielectric fluid. Thanks to the cooling channels, the magnets can be cooled as closely as possible.

[0054] According to the invention, at least one radial arm (preferably at least half of the radial arms, for example every other radial arm successively in the circumferential direction, and more preferably each radial arm) comprises a radial portion of at least one cooling channel. In other words, at least one radial arm is traversed radially, at a radial portion (which is a part of the radial arm) by at least one cooling channel (each cooling channel radially traverses a radial arm). The radial portion is the part of the radial arm which comprises at least one cooling channel, the radial arm possibly comprising another part which is not traversed by a cooling channel. Thus, each permanent magnet can be cooled efficiently and the rotor disk can be cooled homogeneously.Furthermore, due to the positioning of the cooling channels in the radial arms, the cooling channels are close to the stator (in particular the stator coils), with the radial arms facing the stator. In other words, the discoid shape of the rotor disc allows by construction to have cooling channels close to the stator surface. As a result, the cooling channels can also cool the stator (in particular the stator coils).

[0055] By radial portion is meant portions of cooling channels extending radially or substantially radially (i.e. substantially from an inner section to an outer section) from an inner end to an outer end.

[0056] Preferably, the cooling channels can pass through each relevant radial arm over the entire radial length of said radial arm. Thus, the magnets can be cooled over their entire radial length.

[0057] According to a variant, at least one radial arm (preferably at least half of the radial arms, for example one radial arm out of two successively in the circumferential direction, and more preferably each radial arm) can be crossed by a single cooling channel. In this case, there can be as many cooling channels as there are radial arms. This simplifies the manufacture of the rotor disk.

[0058] Advantageously, the permanent magnets may be magnets passing completely through the rotor disc or magnets bonded to the rotor disc. Thus, the invention may be applied to different types of rotors for axial flux electric machines.

[0059] According to one embodiment of the invention, the rotor disk may comprise an inner ring and an outer ring connected to each other by the radial arms, each cooling channel comprising at least one inner portion in the inner ring and preferably an outer portion in the outer ring. Thus, the cooling channels are of great length, which increases the exchange surface and therefore improves the cooling. In addition, the inner portion may be used to supply the cooling channels with fluid. The outer portion may be used, for example, for the outlet of the cooling channels.

[0060] According to a variant of the invention, at least one cooling channel may comprise at least one radial outlet, the radial outlet being able in particular to be positioned in the external portion of the external ring. As a result, the cooling channels are simpler to manufacture, the radial drilling through the radial arms then continuing from the radial outlet to the inlet of the cooling channel.

[0061] Additionally or alternatively, at least one cooling channel may comprise at least one axial outlet and / or at least one outlet inclined at a non-zero angle relative to the axial direction and relative to the radial direction, in a longitudinal plane (i.e. a plane comprising the longitudinal axis). A so-called "inclined" outlet is therefore non-axial and non-radial. In other words, an inclined outlet has an axis that is not orthogonal to the surface of the rotor disk onto which it opens. By using an axial or inclined outlet, it is possible to direct the fluid to one side or the other of the rotor disk, each side being considered in the longitudinal direction. Thus, when stators are positioned on each side of the rotor, the axial or inclined outlet can direct the fluid towards one of the two stators (and more particularly towards the stator coils).Thus, the cooling of the electric machine can be further improved by efficiently cooling both the rotor and the stator.

[0062] According to one embodiment of the invention, at least one cooling channel may comprise two outlets.

[0063] Each outlet of the same cooling channel can be located on one side of the rotor disk (one outlet on one side and the other outlet on the other side), each outlet opening onto each axial end face of the rotor disk, for example so as to be opposite a stator). Thus, the two outlets are on opposite faces of the rotor disk, which makes it possible to cool each of the two stators opposite the rotor (for the machine with two stators and one rotor in particular). These outlets can be axial or inclined.

[0064] Alternatively or additionally, one of the two outlets of the same cooling channel may be a radial outlet and the other of the two outlets may be an axial or inclined outlet. Thus, different parts of the coils can be cooled to better cool them.

[0065] Alternatively, the different cooling channels may each have a (single) outlet. Furthermore, the outlets of the different cooling channels, in the circumferential direction, may be successively and alternately directed to one side and then to the other of the rotor disc. Thus, if an outlet opens onto an axial end face of the rotor disc so as to be opposite one of the two stators, the outlet of the next cooling channel, in the circumferential direction, opens onto the opposite axial end face of the rotor disc so as to be opposite the other of the two stators. Thus, the successive outlets of the different cooling channels are in substantially opposite directions, the outlets being successively and alternately directed towards one stator and then towards the other. These outlets may be axial or inclined.

[0066] By "in substantially opposite directions" is meant that the directions of the fluid flows are not necessarily strictly opposite. They may be strictly opposite when the outlets are axial. When the outlets are inclined, the flows are generally directed towards each stator but the directions of the flows are not strictly opposite, taking into account the inclination of the outlets.

[0067] Advantageously, the different longitudinal (axial) outlets of the cooling channels on the same side of the rotor disk can have different orientations to spray a wider area of ​​the coils. Thanks to the different longitudinal outlets facing the internal surface of the coils, the fluid circulating in the cooling channels can exit through these outlets and thus spray the coils. Indeed, when it exits the longitudinal outlets, it is projected opposite the coils. As a result, the fluid is in contact, at least partially and preferably totally, with the coils.

[0068] According to a configuration of the invention, at least one radial arm (preferably at least half of the radial arms, for example one radial arm out of two successively in the circumferential direction, and more preferably each radial arm) may comprise radial portions of two cooling channels (or at least two cooling channels), each of the two cooling channels (or at least two cooling channels) having a single outlet. In other words, two (or more) cooling channels pass through the same radial arm (preferably each radial arm): there are therefore at least twice as many cooling channels as radial arms. Preferably, each outlet of these two channels opens on a separate side of the rotor disc. This allows the radial arms to be cooled even better, and each cooling channel can cool one of the two stators located on either side of the rotor, with each cooling channel having an outlet directed towards a separate stator. These outlets can be axial or inclined.

[0069] The invention also relates to an axial flux electrical machine comprising at least one stator (comprising coils) and at least one rotor as described in one of the preceding variants or combinations of variants. Indeed, with a rotor as described above, heating of the rotor is reduced and / or its cooling improved. Thus, the current density in the windings can be increased in continuous operation.

[0070] According to the invention, the axial flux machine can thus comprise at least one rotor and at least one stator which are arranged successively one behind the other in the axial direction (of the axis of rotation of the at least one rotor), so that the path of the magnetic flux between each successive rotor and stator (i.e. which follow one another directly) is axial. In other words, each successive rotor and stator face each other and are separated by an air gap of axial thickness (or axial clearance between the rotor and the stator).

[0071] The axial flux electric machine may also comprise a central shaft on which the rotor disc is mounted.

[0072] Advantageously, the axial flux electrical machine may axially comprise a succession of rotors and stators. The multiplication of rotors and / or stators makes it possible to increase performance (torque and power in particular), and this in a restricted space requirement. The at least one stator generally comprises coils for generating or interacting with the permanent magnets of the rotor.

[0073] Preferably, the axial flux electric machine may comprise two rotors and one stator, or two stators and one rotor (so-called "double stator and single rotor" machine) or an alternation of rotors and stators. The rotor of the invention is particularly advantageous when it is "sandwiched" between two stators since the cooling channels can effectively cool the stators on each side of the rotor. By "sandwiched" is meant "arranged between".

[0074] A machine with two rotors and one stator can thus successively axially comprise a first rotor, a central stator (i.e. between the two rotors) and a second rotor.

[0075] A machine with two stators and one rotor can thus successively axially comprise a first stator, a central rotor (i.e. between the two stators) and a second stator.

[0076] A machine with two rotors and two stators can thus successively axially comprise a first rotor, a first stator, a second rotor and a second stator.

[0077] Preferably, at least one cooling channel may comprise at least one outlet directed towards at least one stator of the electrical machine so as to more efficiently cool the stator.

[0078] Preferably, when the electrical machine comprises a stator on each side of a rotor (the electrical machine therefore comprises at least two stators, one on each side of the rotor), each cooling channel may comprise two outlets, one of the two outlets being directed towards one of the two stators and the other of the two outlets being directed towards the other of the two stators. This variant makes it possible to cool the two stators simultaneously, in addition to the rotor.

[0079] Alternatively, when the electrical machine comprises at least one rotor surrounded by two stators, one stator on each side of said at least one rotor (the electrical machine therefore comprises at least two stators, one on each side of the rotor), the rotor disc of the at least one rotor surrounded by two stators may comprise, alternately in the circumferential direction, cooling channels with outlets (axial or inclined) successively and alternately directed towards one stator then towards the other stator. The outlets thus open alternately on one side (on one of the two axial end surfaces of the rotor disc) then on the other (on the other of the two axial end surfaces of the rotor disc) of the rotor to direct the flow towards each stator.

[0080] Advantageously, the electrical machine may comprise a casing. The at least one rotor and the at least one stator may then be positioned in the casing. The casing may serve as an outer casing to protect the stator(s) and rotor(s) and to prevent the cooling fluid from being dispersed into the environment. In other words, the casing also serves to retain and collect the fluid.

[0081] Advantageously, the electrical machine may also comprise a fluid supply system which may comprise a conduit passing through the casing. The conduit allows the fluid to be introduced into the electrical machine.

[0082] Preferably, when the machine comprises a casing and when the cooling channels have at least one radial outlet, the casing may comprise at least one machining (or several machinings) opposite the radial outlets of the cooling channels. These machinings in the casing make it possible to guide the flow of fluid leaving the cooling channels towards the stator, in particular towards the stator coils. By using machinings, it is possible to dispense with additional parts to guide the flow leaving the rotor towards the stator coils. Therefore, this solution is simple and low cost. The machinings of the casing serve as deflectors to direct and guide the flow of fluid leaving the rotor via the radial outlets of the various cooling channels towards the stator, more particularly towards the stator coils.

[0083] Preferably, when the electrical machine has a horizontal longitudinal axis, these machining operations can be located on the upper part of the casing, the upper part being defined, relative to the vertical axis, with the electrical machine in the operating position: in this configuration, the machining operations of the casing are then only on at most one half of the casing.

[0084] According to one embodiment of the invention, each machining can thus comprise at least one concave bowl facilitating the guidance of the flow towards the coils. If the radial outlet is used to cool the coils of two stators, located on either side of the rotor, each machining can comprise two concave bowls juxtaposed to each other so as to separate the flow rate of the flow leaving the rotor into two, preferably into two substantially equal flows, to cool the stators on either side of the rotor.

[0085] In this embodiment, the cooling channels may include axial outlets in addition to the radial outlets and / or some cooling channels may include axial outlets and other cooling channels may include radial outlets so as to further improve cooling of the coils.

[0086] According to one embodiment of the invention, the supply system may comprise a sealed chamber formed between the casing and the rotor disc, the sealed chamber being fluidically connected to the conduit to collect the fluid arriving through the conduit, the inlet of the cooling channel being fluidically connected to the sealed chamber to convey the fluid from the sealed chamber to the cooling channel.

[0087] The sealed chamber may comprise dynamic sealing means without seals (by succession of grooves and without use of seals, also called “labyrinth seals”) or sealing means comprising sealing joints (made of elastomer for example) to ensure its sealing.

[0088] As the rotor rotates, a centrifugal force is generated. This force creates a vacuum in the sealed chamber, and as a result, the fluid is drawn into the cooling channels.

[0089] Alternatively, the supply system may comprise a means for extending the conduit (such as a tube fixed to the end of the conduit on the casing) towards the rotor disc so that the fluid arrives in the rotor disc, by gravity. The rotor disc may then comprise an annular enclosure into which the fluid leaving the extension means falls under the effect of gravity. The annular enclosure is connected to the different inlets of the different cooling channels and can therefore supply the different cooling channels with fluid. This solution does not require sealing means and operates in a simple manner.

[0090] Preferably, each cooling channel may have a substantially axial inlet connected to the supply system (with the sealed chamber or with the annular enclosure).

[0091] According to another variant, the electrical machine may comprise a central shaft on which the rotor disc is fixed and each cooling channel may then have a radial inlet so that the fluid arrives via the central shaft of the electrical machine.

[0092] Preferably, the electrical machine may comprise a fluid collection system at the outlet of the rotor (preferably at the casing) and preferably a fluid reservoir connected to the collection system, downstream of the collection system in the direction of the fluid flow or integrated into the collection system, for the circulation of the fluid in a closed loop and possibly a pump for conveying the fluid from the collection system to said fluid reservoir. Indeed, when the supply system comprises a sealed chamber, it may be that the depression created by the centrifugal force is sufficient to convey the fluid from the reservoir to the cooling channels of the rotor. In this case, a pump can then be dispensed with.In the case where the supply system is gravity-fed, it may be interesting for the electric machine to include a pump to supply the tank and thus, the supply of the fluid can operate by gravity from the tank to the cooling channels, and this in a closed loop.

[0093] The invention also relates to the use of the electric machine according to one of the variants or combinations of variants described above in an electric or hybrid vehicle, a wind turbine, or in a stationary application, such as an industrial charging machine, an electric generator. An “electric” vehicle is a vehicle which comprises an electric machine and which does not comprise an internal combustion engine. A “hybrid” vehicle comprises an electric machine and an internal combustion engine (petrol or Diesel for example). A stationary application is an application in which the electric machine is not in a means of transport. It is stationary relative to a terrestrial reference point. An industrial charging machine is a machine used in industry and an electric generator is a machine capable of supplying electricity to a machine, a system or a factory.A wind turbine may be stationary when it is on land or placed on a seabed. A floating offshore wind turbine may not be completely stationary in the sense that it may undergo movements around an average position.

[0094] [Fig.l] illustrates, in a schematic and non-limiting manner, an example of an axial flux electric machine according to the invention.

[0095] The electrical machine comprises a rotor 1 and two stators 100, one on each side of the rotor 1.

[0096] The rotor 1 rotates around an axis of rotation A shown by the dot-dash line.

[0097] The rotor comprises permanent magnets 4 passing completely through the rotor 1 for be opposite a stator 100 on each side. Thus, the axial size of the electric machine is reduced.

[0098] [Fig. 2] illustrates, in a schematic and non-limiting manner, a rotor of the axial flux electric machine according to the invention. This rotor comprises a rotor disc with radial arms 17 between the permanent magnets 4.

[0099] The rotor comprises cooling channels which radially pass through the radial arms 17. In [Fig.2], the cooling channels are not visible because they are located in the radial arms 17.

[0100] As shown, the rotor disk comprises an inner ring 6 and an outer ring 5. The inner and outer rings 6 and 5 are connected to each other by the radial arms 17.

[0101] The inner ring 6 comprises a central opening so that the rotor disc can be mounted on a central shaft 7.

[0102] The inlet of the cooling channels can arrive via the internal ring 6, either radially or axially, in particular from the central shaft 7, or in a direction inclined at a non-zero angle relative to the radial direction R1 / R2 and relative to the axial direction (orthogonal to the plane of the figure).

[0103] The outlet of the cooling channels can advantageously be via the external ring 5, either radially or axially.

[0104] The permanent magnets 4 are positioned in housings which are delimited by the inner ring 6, by the radial arms 17 and by the outer ring 5. Thus and as shown, the housings and the permanent magnets 4 are substantially trapezoidal in shape, but other shapes could of course be used. For example and as shown, the largest base of the trapezoidal shape may be on the side of the outer periphery of the rotor.

[0105] [Fig. 3] illustrates, in a schematic and non-limiting manner, a first embodiment of a rotor of an axial flux electric machine according to the invention.

[0106] The figure illustrates a sectional view along a plane perpendicular to a radial axis of a radial arm 17.

[0107] The dot-dash arrow represents the axial direction A.

[0108] In the figure, we observe a radial arm 17 located between two permanent magnets 4.

[0109] This radial arm 17 has substantially the same axial length, in the axial direction A, that the permanent magnets 4 located on either side of the radial arm 17.

[0110] The radial arm 17 is crossed by a single cooling channel 10, in which circulates a fluid capable of recovering the heat from the permanent magnets 4 and the coils of the stator opposite the rotor. The rotor shown is a through-magnet rotor.

[0111] [Fig.4] illustrates, in a schematic and non-limiting manner, a second embodiment of a rotor of an axial flux electric machine according to the invention.

[0112] The figure illustrates a sectional view along a plane perpendicular to a radial axis of a radial arm 17.

[0113] The dot-dash arrow represents the axial direction A.

[0114] In the figure, we observe a radial arm 17 located between two permanent magnets 4.

[0115] This radial arm 17 has substantially the same axial length, in the axial direction A, that the permanent magnets 4 located on either side of the radial arm 17.

[0116] The radial arm 17 is crossed by two cooling channels 10, in which circulates a fluid capable of recovering the heat from the permanent magnets 4 and the coils of the stator opposite the rotor. The rotor shown is a through-magnet rotor.

[0117] Alternatively, the rotor of Figures 3 and 4 could not be a through-magnet rotor but a rotor where the magnets are bonded to the rotor disc with radial arms separating the magnets.

[0118] Figures 5 to 9 illustrate, in a schematic and non-limiting manner, different variants of cooling channels of an axial flux electric machine rotor according to the invention.

[0119] In these different figures, axis A represents the longitudinal axis of the electrical machine (and therefore the axis of rotation of the rotor).

[0120] These figures are all represented in section in a plane passing through the longitudinal axis A and through a radial axis passing through a radial arm 17 of the rotor disk.

[0121] The rotor disk comprises an inner ring 6 and an outer ring 5 connected to each other by several radial arms 17.

[0122] The rotor disk comprises cooling channels 10.

[0123] In [Fig.5], each cooling channel 10 has a radial portion 11, radially passing through a radial arm 17. Here, each radial arm 17 comprises a single radial portion 11 of a cooling channel. In other words, there are as many cooling channels 10 as there are radial arms 17. Of course, each radial arm could comprise more than one radial portion, i.e. at least two radial portions.

[0124] The fluid arrives from the internal ring 6, passes into the cooling channel 10, in particular into the radial portion 11, then exits through the two outlets S1 and S2. Each of these two outlets S1 and S2 is connected to the same cooling channel. These outlets S1 and S2 are inclined at a non-zero angle α relative to the longitudinal axis A and at a non-zero angle relative to the radial axis. These outlets are directed in opposite directions, that is to say that they each open onto a lateral surface of the rotor distinct from one another.

[0125] In [Fig.6], each cooling channel 10 has a radial portion 11, radially passing through a radial arm 17. Here, as for [Fig.5], each radial arm 17 comprises a single radial portion 11 of a cooling channel. In other words, there are as many cooling channels 10 as there are radial arms 17. Of course, each radial arm could comprise more than one radial portion, i.e. at least two radial portions.

[0126] The fluid arrives from the internal ring 6, passes into the cooling channel 10, in particular into the radial portion 11, then exits through the single outlet SI. The outlets of the different cooling channels passing through each radial arm 17 can be alternately directed to one side of the rotor then to the other. They therefore each open alternately onto a lateral surface of the rotor distinct from the previous outlet and the following outlet, the previous and following outlet being understood in the circumferential direction of the rotor.

[0127] The outlets SI are here longitudinal (axial) but they could be inclined by a non-zero angle and less than 90% relative to the radial direction without departing from the scope of the invention. Here the angle formed between the axis 104 of the cooling channel and the axis 105 of the longitudinal outlet is 90° but it could be an angle other than 90°.

[0128] In [Fig.7], each cooling channel 10 has a radial portion 11, radially passing through a radial arm 17. Here, as for figures 5 and 6, each radial arm 17 comprises a single radial portion 11 of a cooling channel. In other words, there are as many cooling channels 10 as there are radial arms 17. Of course, each radial arm could comprise more than one radial portion, that is to say at least two radial portions.

[0129] The fluid arrives from the internal ring 6, passes into the cooling channels 10, in particular into each radial portion 11, then exits through the outlets SI and S2 of the cooling channel. Each of these two outlets SI and S2 is connected to the same cooling channel. These outlets SI and S2 are oriented in the longitudinal direction and they are directed, relative to each other, in opposite directions, that is to say that they each open onto a lateral surface of the rotor distinct from each other.

[0130] The outlets S1 and S2 are here longitudinal (axial) but they could be inclined by a non-zero angle and less than 90% relative to the radial direction without departing from the scope of the invention. Here the angles formed between the axis 104 of the cooling channel and the axis 105 of the longitudinal outlets S2 and S2 are 90° but they could be different from 90°.

[0131] The different longitudinal or inclined outlets of the cooling channels on the same side of the rotor disk may have different orientations and / or positions. different radials to spray a wider area of ​​the coils.

[0132] In [Fig. 8], each cooling channel 10 has a radial portion 11, radially passing through a radial arm 17. Here, unlike in FIGS. 5, 6 and 7, each radial arm 17 comprises several radial portions 11 and therefore several cooling channels (here two radial portions 11 and two cooling channels 10 but another number of cooling channels and / or radial portions could be envisaged without departing from the scope of the invention). In other words, there are twice as many cooling channels 10 as radial arms 17.

[0133] The fluid arrives from the internal ring 6, passes into the cooling channels 10, in particular into the radial portions 11, then exits through the single outlet SI of each of the two cooling channels. Here, the outlets SI are radial but they could be longitudinal or inclined at a non-zero angle relative to the longitudinal axis and relative to the radial axis without departing from the scope of the invention. For example, the outlet of one channel could open onto a lateral surface of the rotor disk and the outlet of the other channel could open onto the other lateral surface of the rotor disk. According to another variant, one outlet of a channel could be radial and another outlet of another channel could be axial or inclined, so as to cool the coils even better.

[0134] In [Fig.9], each cooling channel 10 has a radial portion 11, radially passing through a radial arm 17. Here, unlike in figures 5, 6 and 7, each radial arm 17 comprises several radial portions 11 and therefore several cooling channels (here two radial portions and two cooling channels but another number of cooling channels and / or radial portions could be envisaged outside the scope of the invention). In other words, there are twice as many cooling channels 10 as radial arms 17.

[0135] The fluid arrives from the internal ring 6, passes into the cooling channels 10, in particular into the radial portions 11, then exits through the single outlet SI of each of the two cooling channels. Here, the outlets SI are longitudinal (but could be inclined at a non-zero angle relative to the longitudinal axis and relative to the radial axis without leaving the scope of the invention).

[0136] [Fig. 10] illustrates, in a schematic and non-limiting manner, a first embodiment of a fluid supply system for a rotor of an axial flux electric machine according to the invention.

[0137] The electrical machine comprises a casing 18 (the casing 18 is only partially shown), a central shaft 7 and a rotor disc 20. As shown, the central shaft 7 and the rotor disc 20 are in one piece but they could be made in two separate pieces and assembled by any means allowing them to be fixed to each other, by welding or screwing for example.

[0138] The casing 18 comprises a conduit 24 passing through the casing 18 so as to allow the supply of cooling fluid to the electrical machine.

[0139] The casing 18 is connected to the central shaft 7 by bearings 19 so as to allow rotation of the central shaft 7 in the casing 18 which is fixed.

[0140] The casing 18 extends to the rotor disc 20 and sealing means 22 and 23 (dynamic seals for example) are positioned between the casing 18 and the rotor disc 20 so as to form a sealed chamber 21.

[0141] The conduit 24 opens into the sealed chamber 21 to supply this sealed chamber 21 with fluid. In addition, the inlet of the cooling channels 10 arrives in the sealed chamber 21. In other words, the conduit 24, the sealed chamber 21 and the cooling channels 10 are fluidically connected to each other.

[0142] The rotation of the central shaft 7 and the rotor disc 20 drives the fluid contained in the sealed chamber 21 into the cooling channels 10 and in particular into the radial parts of these cooling channels 10 which are located in the radial arms 17 of the rotor disc 20.

[0143] In this embodiment, the inlets of the cooling channels 10, connected to the supply system, are substantially axial, arriving in the sealed chamber 21.

[0144] The bold black arrows represent the fluid supply. The fluid arrives via the conduit 24, it passes through the casing 18 to arrive in the sealed chamber 21 then it joins the cooling channels 10.

[0145] [Fig. 11] illustrates, in a schematic and non-limiting manner, a second embodiment of a fluid supply system for a rotor of an axial flux electric machine according to the invention.

[0146] The electric machine comprises a casing 18 (the casing 18 is only partially shown), a central shaft 7 (also partially shown) and a rotor disc 20.

[0147] As shown, the central shaft 7 and the rotor disc 20 are in one piece but they could be made in two separate pieces and assembled by any means allowing them to be fixed to each other, by welding or screwing for example.

[0148] The figure shown illustrates two variants which can be used independently of each other or in combination. In one case, the cooling fluid arrives through the central shaft via the conduit 24b. In another case, the cooling fluid arrives through the housing flange via the conduit 24a. Of course, the electric machine can combine these two variants.

[0149] The casing 18 comprises a conduit 24a and / or a conduit 24b passing through the casing 18 so as to allow the supply of cooling fluid to the electric machine. In other words, the supply of cooling fluid to the machine electric power can arrive either through conduit 24a, or through conduit 24b, or through both conduit 24a and conduit 24b.

[0150] The casing 18 is connected to the central shaft 7 by bearings 19 so as to allow rotation of the central shaft 7 in the casing 18 which is fixed.

[0151] In this embodiment, the power supply system does not require sealing means between the casing 18 and the rotor disc 20.

[0152] In the case where the fluid is supplied by the conduit 24b, the fluid arrives in the rotor disk by centrifugation in the collection zone 28 of the rotor disk 20.

[0153] This solution can in particular be used in combination with the solution variants of Figures 5 to 9.

[0154] In the case where the fluid is supplied by the conduit 24a, the conduit is extended by the extension means 25 (which may be a tube partly shrunk to the casing or welded to the casing). The extension means 25 ends in the collection zone 28 of the rotor disc 20 so as to supply the fluid into the collection zone 28, by gravity.

[0155] Once in the collection zone 28, the fluid can feed the cooling channels 10. The rotation of the rotor disc 20 makes it possible to feed the different cooling channels 10 one after the other. In addition, by centrifugation, the fluid present in the collection zone 28 is distributed uniformly throughout this annular cavity, which then simultaneously feeds all the channels of the rotor.

[0156] The collection zone 28 thus forms an annular enclosure of the rotor disk 20 connected to the different inlets of the different cooling channels 10.

[0157] In this embodiment, the inlets of the cooling channels 10, connected to the supply system, are substantially radial, arriving in the collection zone 28.

[0158] The bold black arrows represent the fluid supply. The fluid arrives via the conduit 24a and / or via the conduit 24b, and arrives in the collection zone 28 where it then joins the cooling channels 10.

[0159] [Fig. 12] illustrates, in a schematic and non-limiting manner, a configuration of the axial flux electric machine according to the invention.

[0160] The electrical machine comprises a rotor 1 and two stators 100, each stator 100 being located on either side of the rotor 1. The chain-dotted axis A illustrates the longitudinal axis of the electrical machine and the axis of rotation of the rotor.

[0161] The rotor 1 comprises permanent magnets 4.

[0162] The rotor 1 and the stators are positioned in a casing 200 of the electric machine which protects both the rotor 1 and the stators 100 and which prevents the dispersion of the cooling fluid into the atmosphere.

[0163] The electric machine comprises a fluid collection system 201 here positioned on the lower part of the casing, so as to recover the fluid by gravity in the collection system 201. The lower part extends in the operating position of the electric machine, relative to the vertical direction.

[0164] Furthermore, the electrical machine comprises a fluid reservoir 202 fluidly connected to the collection system 201. The fluid reservoir 202 is downstream of the collection system in the direction of fluid flow. As shown, the fluid reservoir 202 is positioned outside the casing 200 but it could also be inside the electrical machine, for example by being integrated into the casing or the collection system 201.

[0165] The fluid reservoir 202 is also fluidically connected to the fluid supply system 205 which can advantageously be positioned on the casing 200, in the casing 200 or in the electrical machine. The fluid supply system 205 is positioned downstream of the reservoir, in the direction of circulation of the fluid. Thus, the fluid circuit formed by the pipes 204 successively connecting the fluid collection means 201, the fluid reservoir 202 and the fluid supply system 205 as well as the electrical machine, constitutes a closed-loop circuit for the circulation of the fluid in a closed loop.

[0166] Optionally, the closed-loop circuit may also comprise a pump 203 to facilitate the circulation of the fluid in this loop. The pump 203 is shown in a broken line representing its optional nature. The pump 203 is here positioned between the fluid reservoir 202 and the fluid supply system 205 but it could be positioned elsewhere on this circuit, in particular for example between the fluid collection means 201 and the fluid reservoir 202 (this is particularly advantageous for a gravity supply system, the reservoir can then be positioned vertically above the fluid supply system 205 in the operating position). The pump could also be installed directly in the reservoir.

[0167] The pump 203 may be electrically or mechanically actuated by the rotor.

[0168] When the fluid supply system 205 comprises a sealed chamber, it may be that the depression created by the centrifugal force is sufficient to convey the fluid to the reservoir. In this case, the pump 203 can then be dispensed with.

[0169] In the case where the fluid supply system 205 is gravity-fed, it may be advantageous for the closed-loop circuit to include the pump 203 to supply the fluid reservoir 202 and thus, the fluid supply can operate by gravity from the fluid reservoir 202 to the fluid supply system 205 to then reach the various cooling channels of the electrical machine (within the rotor 1), and this in a closed loop.

[0170] [Fig. 13] illustrates, in a schematic and non-limiting manner, an embodiment of an axial flux electric machine according to the invention.

[0171] Diagram a) illustrates the electric machine in a longitudinal plane and diagram b) by a plane orthogonal to the longitudinal axis.

[0172] The electrical machine comprises a casing 18 (partially shown), a central shaft 7 and a rotor disc 20 as well as a stator comprising a stator body 26 and coils 27.

[0173] The central shaft 7 comprises a central bore 29 acting as a fluid supply system. The central bore 29 is connected to radial bores 30 allowing the fluid connection between the central bore 29 and the different cooling channels 10 of the rotor disk 20. Thus, each radial bore 30 is connected to the central bore 29 and to at least one cooling channel 10.

[0174] The outlets of the different cooling channels 10 are radial and therefore face the casing 18.

[0175] In order to facilitate the exit of the fluid and to direct the fluid, in particular towards the coils 27 to cool them, the casing 18 comprises, opposite these exits and preferably opposite the coils 27, two machinings 28a and 28b, which here each take the form of concave bowls.

[0176] In diagram b), we can observe the flow of the fluid around the coils, which is done by gravity when the axis of the electrical machine is horizontal, the flow being represented by the arrows.

[0177] [Fig. 14] illustrates, in a schematic and non-limiting manner, a sixth variant of a rotor of an axial flux electric machine according to the invention. This rotor comprises a rotor disc with radial arms 17 between the permanent magnets 4.

[0178] Diagram a) illustrates a view of an axial end surface of the rotor and diagram b) illustrates a view of the axial end surface opposite that of diagram a).

[0179] The rotor comprises cooling channels which radially pass through the radial arms 17. In [Fig. 14], the cooling channels are not visible because they are located in the radial arms 17; only the outlets 101 and 102 are visible.

[0180] As shown, the rotor disk comprises an inner ring 6 and an outer ring 5. The inner and outer rings 6 and 5 are connected to each other by the radial arms 17.

[0181] The inner ring 6 comprises a central opening so that the rotor disc can be mounted on a central shaft 7.

[0182] The inlet of the cooling channels can arrive via the internal ring 6, either radially or axially, in particular from the central shaft 7, or in a direction inclined at a non-zero angle relative to the radial direction R1 / R2 and relative to the axial direction (orthogonal to the plane of the figure).

[0183] The permanent magnets 4 are positioned in housings which are delimited by the internal ring 6, by the radial arms 17 and by the external ring 5. Thus and such that re shown, the housings and the permanent magnets 4 are substantially trapezoidal in shape, but other shapes could of course be used. For example and as shown, the largest base of the trapezoidal shape may be on the side of the outer periphery of the rotor.

[0184] The outlets 101 and 102 of the different cooling channels open into the axial end surfaces of the rotor disk. The outlets 101 open onto one of the two axial end surfaces, corresponding to diagram a), while the outlets 102 open onto the other of the two axial end surfaces, corresponding to diagram b).

[0185] As shown, the different cooling channels each have a (single) outlet 101 or 102. Furthermore, the outlets 101 and 102 of the different cooling channels, in the circumferential direction, are successively and alternately directed to one side then to the other of the rotor disc. In other words, the outlets 101 and 102 open successively and alternately, in the circumferential direction onto one of the two axial end surfaces of the rotor disc (of diagram a)) then onto the other of the two axial end surfaces of the rotor disc (of diagram b)). Thus, the successive outlets 101 and 102 of the different cooling channels are in substantially opposite directions.

[0186] The radial position of the outlets 101 and 102 is illustrative. Of course, this radial position could be offset outwards, at the level of the external ring 5 for example, or else offset inwards.

[0187] Of course, the invention is not limited to the embodiments shown but also incorporates combinations of these embodiments as well as equivalent embodiments and their combinations.

Claims

Claims

1. Rotor (1) for an axial flux electrical machine comprising a rotor disc (20) made of metallic material and permanent magnets (4), the rotor disc (20) comprising housings, preferably of substantially trapezoidal section, distributed circumferentially within the rotor disc (20), the permanent magnets (4) being positioned in said housings, the rotor disc (20) comprising cooling channels (10) for the circulation of a fluid from the inside to the outside in the cooling channels (10), characterized in that the rotor disc (20) comprises radial arms (17) separating said housings, and in that at least one of the radial arms (17) comprises a radial portion (11) of at least one cooling channel (10).

2. Rotor according to claim 1, wherein the permanent magnets (4) are magnets passing completely through the rotor disc (20) or magnets glued to the rotor disc (20).

3. Rotor according to one of the preceding claims, wherein the rotor disc (20) comprises an inner ring (6) and an outer ring (5) connected together by said radial arms (17), each cooling channel (10) comprising at least one inner portion in the inner ring (6) and preferably an outer portion in the outer ring (5).

4. Rotor according to one of the preceding claims, wherein at least one of the at least one cooling channel (10) comprises at least one radial outlet.

5. Rotor according to one of the preceding claims, in which at least one cooling channel (10) comprises at least one axial outlet and / or at least one outlet inclined at a non-zero angle relative to the axial direction and relative to the radial direction.

6. Rotor according to claim 5, wherein at least one cooling channel (10) comprises two outlets (SI, S2), one outlet on each side of the rotor disc (20) or one radial outlet and one axial or inclined outlet, or wherein the different cooling channels (10) each have one outlet (SI), the outlets (SI) of the different cooling channels (10), in the circumferential direction, being successively and alternately directed to one side then to the other of the rotor disc (20).

7. Rotor according to one of claims 5 or 6, in which at least one radial arm (17) comprises radial portions (11) of two cooling channels (10), each of the two cooling channels (10) having a single outlet (SI), preferably each outlet (SI) of these two cooling channels (10) opening on a separate side of the rotor disc (20).

8. An axial flux electric machine comprising at least one stator (100) and at least one rotor (1) according to one of the preceding claims and preferably comprising two rotors (1) and one stator (100), or two stators (100) and one rotor (1) or two stators (100) and two rotors (1).

9. An electrical machine according to claim 8, wherein at least one cooling channel (10) comprises at least one outlet directed towards at least one stator (100) of the electrical machine, and preferably, when the electrical machine comprises a stator (100) on each side of a rotor (1), each cooling channel (10) comprises two outlets (SI, S2), one directed towards one stator (100) and the other directed towards the other stator (100) or each rotor disc of the rotor (1) comprises alternately in the circumferential direction cooling channels (10) with outlets (SI) successively and alternately directed towards one stator (100) and then towards the other stator (100).

10. An electrical machine according to one of claims 8 or 9, wherein the electrical machine comprises a housing (200, 18), the at least one rotor (1) and the at least one stator (100) being positioned in the housing (200, 18), and a fluid supply system (205) comprising a conduit (24, 24a, 24b) passing through the housing (200, 18).

11. An electrical machine according to claim 10, wherein the power system (205) comprises a sealed chamber (21) formed between the housing (200, 18) and the rotor disc (20), the sealed chamber (21) being fluidically connected to the conduit (24, 24a, 24b), the inlet of the cooling channel (10) being fluidically connected to said sealed chamber (21) for conveying fluid from said sealed chamber (21) to the cooling channel (10).

12. Electrical machine according to claim 10, in which the supply system (205) comprises an extension means (25) of the conduit (24, 24a, 24b) in the direction of the rotor disc (20) so that the fluid arrives in the rotor disc (20), by gravity, in an annular enclosure of the rotor disc (20) connected to the different inlets of the different cooling channels (10).

13. Electric machine according to one of claims 10 to 12 with a rotor according to claim 4, in which the casing (200, 18) comprises at least one machining (28a, 28b) opposite the radial outlets to direct the flow of fluid leaving the rotor towards the at least one stator.

14. An electrical machine according to any one of claims 8 to 13, wherein the electrical machine comprises a central shaft (7) on which the rotor disc (20) is fixed and wherein each cooling channel (10) has a substantially axial inlet connected to said supply system (205) or a radial inlet so that the fluid arrives via said central shaft (7) of the electrical machine.

15. An electrical machine according to one of claims 8 to 14, wherein the electrical machine comprises a fluid collection system (201) at the outlet of the rotor (1) and preferably a fluid reservoir (202) connected to the collection system (201), downstream of the collection system (201) or integrated into the collection system (201) in the direction of fluid flow, for circulating the fluid in a closed loop and possibly a pump (203) for conveying the fluid from the collection system (201) to said fluid reservoir (202), the reservoir preferably being integrated into the casing

16. Use of the electric machine according to one of the preceding claims in an electric or hybrid vehicle, or in a stationary application, such as an industrial charging machine, an electric generator or a wind turbine.

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