Axial flux inductor of a synchronous electrical machine

Abstract

TITLE IN APPBODY-TITLE One aspect of the invention relates to an inductor I of an axial flux synchronous electric machine M1', the inductor I comprising a first series of salient poles 1 and a second series of salient poles 1, 2 each situated between two salient poles 1 of the first series, each comprising a coil body 21 and an excitation coil 22 of the second series of salient poles 2 comprises turns wound around a covered wound portion 210 of the coil body 21 forming active portions in at least a portion of each slot 3 on each side of the coil body 21 formed between a bare portion 11n of a base 11 of a neighboring pole of the first series and the coil body, such that the last turn is closer to each of the two neighboring bare portions 11n than to the coil body. Figure to be published with the abbreviation: Figure 3

Description

Title of the invention: Axial flux inductor of a synchronous electric machine TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of axial flux synchronous electrical machines, in particular the axial flux inductor.

[0002] The present invention relates to the axial flux inductor and in particular to different embodiments of axial flux synchronous electrical machines comprising such an axial flux inductor. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] The synchronous machine comprises, like any electric motor, a rotor and a stator, mainly the rotor forms the inductor and the stator forms the armature. In the state of the art, inductors for synchronous electric machines are known, wound and / or with magnets. The inductor may have an advantage in being wound. Indeed, a machine with a wound iron core can produce a higher induction than those with magnets which are also more expensive and thermally limited by their characteristics than a coil. Thus at iso volume, a synchronous electric machine comprising a magnet inductor will be more expensive, more thermally limited and less efficient (torque) particularly at high rotation speed than a machine compared to an electric machine comprising a wound inductor.

[0004] There are also mainly two main families of air gaps known in electrical machines.

[0005] A first family of synchronous electrical machine has a radial air gap, the flux of which is mainly radial, also called field, the air gap volume of which between a stator comprising coils forming the armature and the rotor forming an inductor (magnet or wound) is cylindrical in shape surrounding the axis of rotation of the rotor.

[0006] A second family of synchronous electrical machine has an axial air gap, the flux of which is mainly axial, also called an axial field, and the air gap volume of which between a stator comprising coils forming the armature and the rotor forming the inductor (magnet or wound) is in the form of a disc perpendicular to the axis of rotation of the rotor.

[0007] A transverse flux family is also known, having an axial air gap part and a radial air gap part.

[0008] The advantage of the axial air gap machine is to use the maximum diameter of the machine for the air gap surface, but the larger the useful air gap diameter, the greater the torque. In addition, these machines can also be chosen for reasons of axial size much lower than those of machines with radial air gap having the advantage of radial size.

[0009] there are also inductor rotors with salient poles or claws.

[0010] Claw rotors comprise a single coil wound around the axis of rotation passing through the claws. This makes it possible to have ampere turns produced by this coil passing through each pole having the advantage of improving the conductor rate per slot and therefore increasing the torque as well as reducing joule losses. However, the disadvantage is that the claws are subjected to a concentration of deformation stress at the foot of the claws by centrifugal force requiring a sufficiently large air gap depending on the manufacturing tolerances of the internal diameter of the armature and the external diameter of the claws. However, the larger the air gap, the more the performance of the synchronous electrical machine decreases. In addition, these claws have the disadvantage of having leakage fluxes not crossing the air gap, not contributing to the supply of torque.

[0011] Among the synchronous machines there is the electric machine with a salient pole inductor comprising a ferromagnetic frame, a plurality of ferromagnetic bodies distributed angularly extending axially from the frame and a coil per ferromagnetic body. Each coil is wound around one of the ferromagnetic bodies.

[0012] There is therefore a need to have a synchronous electrical machine architecture of an axial flux wound inductor that is simpler to manufacture in order to reduce the cost while improving the efficiency and torque. Summary of the invention

[0013] The invention provides a solution to the problems discussed above by allowing an excitation coil surrounding a portion of a coil body to have more turns than in the prior art.

[0014] One aspect of the invention relates to an inductor of an axial flux synchronous electrical machine, the inductor being of the salient pole type comprising: • a first series of salient poles each comprising a ferromagnetic base regularly distributed angularly around the central axis, and a beak extending from the ferromagnetic base comprising a radial surface of axial air gap, each ferromagnetic base comprising at least one bare part, • a second series of salient poles, each located between two salient poles of the first series, each salient pole of the second series comprising at least: a coil body comprising a wound covered portion, • an excitation coil wound around the covered wound part of the coil body, • a radial face of axial air gap. • notches, each formed between a coil body of the salient poles of the second series and a neighboring base of one of the neighboring salient poles of the first series, • characterized in that each excitation coil of the second series of salient poles comprises turns wrapped around the covered wound portion of the coil body forming active portions in at least a portion of each notch on each side of the coil body formed with the bare portion of the base of a neighboring salient pole of the first series, such that the last turn is closer to each of the two bare portions of the two neighboring bases of salient pole of the first series, than to the coil body.

[0015] Thanks to the invention, having a bare part on a base of a first series of poles allows the excitation coil of the neighboring pole of the second series to be more voluminous. By bare part is therefore meant a part of a ferromagnetic base or of a coil body not surrounded by a single wound excitation coil, that is to say that there is no coil wound around this bare part but this bare part faces excitation coils of neighboring pole. It is thus possible to have a higher filling rate than inductors having only identical wound salient poles.Indeed, for example, having one wound pole out of two allows both to have an inductor that is easier to manufacture (for example, only one coil out of two) and also for these wound poles to have a higher conductor rate in the slot since, unlike in the case of inductors having only identical wound salient poles, there are no necessary gaps between the coils. In addition, the fact of being an axial flux inductor makes it possible to retain turns radially in this slot easily by keeping the same winding axis parallel to the central axis, unlike in the case of a radial flux inductor, due to the changing angle during winding around an axis perpendicular to the central axis, this implies areas (middle area in the slot) not retained by the beak against centrifugal force. These unretained areas require shims or hoops at the air gap, reducing the filling rate in the slot. .

[0016] In addition to the characteristics which have just been mentioned in the preceding paragraph, the inductor according to one aspect of the invention may have one or more complementary characteristics among the following, considered individually or according to all technically possible combinations: • According to one embodiment, at least one excitation coil comprises its last turn in contact with the bare part of at least one base of one of the two neighboring salient poles. This maximizes the % conductor filling rate in a slot. For example, each excitation coil has its last turn in contact with the bare part. According to one embodiment, at least one excitation coil comprises its last turn distant from the bare part of each base of the two neighboring salient poles by a distance less than a diameter or a width or a length of a section of the conductor of the excitation coil. This makes it possible to maximize the % of conductor filling rate in a slot. According to one example, each excitation coil has its last turn distant according to this distance from the bare part. According to another example, each coil has either its last turn distant according to this distance from the bare part or its last turn in contact with the bare part as in the previous embodiment. According to one embodiment, the inductor further comprises inter-pole magnets positioned between each salient pole of the first series and each salient pole of the second series at the axial air gap face and radial surface. This makes it possible to increase the magnetic saturation level of the poles and therefore to have a greater inductor current before saturation and therefore the possibility of having more torque. According to a variant of the previous embodiment, the inductor comprises a damper cage formed by electrical conductors comprising inter-pole parts each located between each pole at the notch axially covering the coils and an external cylindrical part surrounding the bare poles and the wound poles and an internal cylindrical part surrounded by the bare poles and the wound poles, the internal cylindrical part being electrically connected to the external cylindrical part by the inter-pole parts. The damper cage absorbs the torque variations (stabilization of the instantaneous rotation speed) caused by a sudden variation in the load and acts in the event of an asymmetrical load (one of the phases interrupted) or in the event of a short circuit. It also facilitates the synchronization and maintenance of several alternators (damping of phase oscillations between alternators). According to one embodiment, at least one or all of the coil bodies are made of paramagnetic or diamagnetic material, in particular a material lighter than the ferromagnetic material of the bases. This makes it possible to reduce the weight of the machine, for example, each coil body comprises a plastic frame on which the first turn(s) of the coil are wound and air is located in the frame. Such a coil body is therefore lighter and less expensive than the following embodiment. According to one embodiment or a variant of the embodiment, at least or all of the coil bodies are made of ferromagnetic material and in that each radial face of axial air gap is formed of a radial surface of axial air gap. This makes it possible to channel (guide) and promote the magnetic flux. According to one embodiment, • each coil body comprises a bare portion extending from the covered wound portion, • each ferromagnetic base of a salient pole of the first series comprises a second covered wound portion of the ferromagnetic base extending from the first bare portion, and • in that each salient pole of the first series comprises an excitation coil wound around the second covered wound part having a last turn closer to each neighboring bare part of the coil body of the two neighboring salient poles of the first series than to the second covered wound part, this makes it possible to be a central axial flux inductor of a double armature machine on either side axially of the inductor. According to an example of the two preceding embodiments, the inductor is a central inductor in which: • the coil bodies are each ferromagnetic and each comprise a first radial surface of axial air gap and • the coil bodies and the ferromagnetic bases each comprise a second radial axial air gap surface opposite the first radial axial air gap surface. This makes it possible to have a central inductor comprising ferromagnetic coil bodies for guiding the axial flux. According to a variant of the previous embodiment, the inductor is a single-layer lateral inductor comprising a ferromagnetic frame comprising a radial face relative to the central axis, in which: • each salient pole of the first series extends axially from a radial face of the ferromagnetic frame, comprising only the bare part extending from the frame to the tip and • each coil body of the second series extending axially from the radial face of the ferromagnetic frame comprising only the covered wound portion of the coil body extending axially from the frame, the excitation coil entirely surrounding only the covered wound part: Unlike the previous embodiment, this allows it to be a lateral axial flux inductor.

[0017] Another aspect of the invention relates to an axial flux synchronous electric machine: • an inductor according to the first aspect of the invention with or without different characteristics of one or more embodiments described previously, • a rotor shaft having an axis of rotation (X) corresponding to the central axis, • a stator armature comprising: • a winding comprising a number Pa of active parts regularly angularly distributed around the axis of rotation surrounding the rotor shaft a winding comprising active parts in notches, • a radial face of axial air gap. This machine can either be an electric machine with a single inductor and a single armature or be an electric machine with a double inductor and an armature or with a double armature and a single inductor but also be with a stator inductor with a ferromagnetic rotor described in one of the embodiments below. In addition, the winding of the armature can be concentric or distributed, in particular it is also possible to have an armature comprising a concentric winding having one coil out of 2 like the inductor, or even an armature formed by teeth or coil bodies made of amagnetic or paramagnetic material, for example resin and fiberglass or even a PCB type electronic card comprising the active parts.

[0018] In addition to the characteristics which have just been mentioned in the preceding paragraph, the inductor according to one aspect of the invention may have one or more complementary characteristics among the following, considered individually or according to all technically possible combinations:

[0019] According to one embodiment, the inductor is integral with the rotor shaft and together forms a rotor, each axial air gap radial surface being opposite the axial air gap radial face of the armature forming an axial air gap between them. The inductor is part of the rotor in this machine.

[0020] According to an example of this embodiment, the rotor further comprises a hoop surrounding and in contact with the poles of the inductor. This makes it possible to maintain the coils, coil body and ferromagnetic body of the inductor against centrifugal force.

[0021] According to a particularity of this example, the fret comprises an external part forming a housing receiving a portion of the winding, the housing having a diameter external to the diameter of the inductor. Such a hoop may be fitted onto the inductor, in particular onto the winding or onto a beak of the coil body. According to an example of this feature, the hoop comprises an internal portion fitted onto the rotor shaft and forming a second housing housing another portion of the coil body. The coil body may thus be a resin embedded in the housings.

[0022] According to an example of this embodiment, the inductor comprises an internal radius and an external radius measured radially respectively between an internal radial end of the beak closest to the central axis and an external radial end of the beak furthest from the central axis and in that the internal radius is equal to 60% + or - 20% of the external radius and • the rotor further comprises a device for supplying the excitation coils of the inductor comprising: • a rotating part integral with the rotor shaft and electrically connected to the excitation coils, being located axially between an axial end of an armature or inductor and an axial end of another armature or another inductor axially opposite this axial end, • a stator part rotationally fixed to the stator armature. This allows for an axially compact electric machine; in fact, the optimal Axial Flux machine will have an active part diameter (of the inductor or armature) approximately equal to 60% of the external diameter of the active part. Thus, by placing the rotating part of the machine's power supply device in the space available inside the internal diameter of the inductor / and the armature, the machine is more axially compact. The axial ends of the armature or the inductor can be an axial end of an inductor frame opposite its axial air gap radial face or an end of an armature yoke opposite its axial air gap radial face.

[0023] According to a variant of this embodiment, the inductor is stator surrounding the rotor shaft, the machine further comprising a ferromagnetic rotor comprising the rotor shaft and a first set of ferromagnetic parts comprising a number Ns of parts regularly distributed around the axis of rotation, the number Ns is equal to the sum of or the difference between Pa / 2 and Pe / 2, the set of ferromagnetic parts being located between the first stator inductor and the first stator armature. This makes it possible to have a stator inductor and therefore not to have a problem against centrifugal force or to have a power supply device comprising a moving part.

[0024] According to one embodiment, the machine comprises a second inductor identical to the first inductor comprising a ferromagnetic frame, the armature being an armature centrally located axially between the two inductors, the armature comprising a second radial axial air gap face per tooth, and the two inductors are angularly offset from each other by one pole such that each pole of the second series of one of the inductors is axially aligned with a pole of the first series of the other inductor. Such a machine having an even number of inductors having only one excitation coil out of 2 also makes it possible to better fill the slots and save manufacturing and assembly time and avoid even harmonics compared to an electrical machine comprising an odd number of inductors. Such a machine also makes it possible to have a balancing of the axial forces between the armature and the inductor.

[0025] According to an example of this embodiment, the coils are embedded in resin, for example with fiberglass or etched on an electrical printed circuit, for example PCB. According to a variant, the stator comprises ferromagnetic teeth held together by an internal or external yoke or embedded in resin, the coils being wound between the teeth, for example around in the case of concentric winding.

[0026] According to an example of this embodiment in which the inductor is according to the embodiment comprising magnets, each magnet of the first inductor has a polarity opposite to the polarity of an axially aligned magnet of the second inductor. This makes it possible to improve the maximum performance of the machine.

[0027] According to another embodiment, the electrical machine comprises a second stator armature identical to the first armature, the inductor is according to the embodiment of which each ferromagnetic polar body comprises a second radial axial air gap surface, the inductor being a central inductor located axially between the two armatures and each armature comprises a yoke and teeth extending from the yoke towards the central inductor forming between them notches of the number Pa each housing an active part. Such a machine makes it possible to have a balancing of the axial forces between the armature and the inductor.

[0028] According to one embodiment, the armature comprises a yoke and teeth extend from the yoke towards the central inductor forming between them notches of number Pa each housing an active part.

[0029] According to one embodiment, the rotor shaft further comprises a cooling channel comprising an axial duct extending axially in the rotor shaft and at least one spray duct extending from the axial duct to an opening opposite a coil of the armature or the inductor. This makes it possible to use the rotor shaft as a system for spraying a coolant onto the inductor coils and / or the winding of the armature in order to increase the efficiency of the machine.

[0030] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0031] The figures are presented for information purposes only and in no way limit the invention.

[0032] [Fig.lA] shows a schematic view of an inductor according to a first example of a first embodiment.

[0033] [Fig.lB] shows a section of the inductor of [Fig.lA].

[0034] [Fig.lC] shows a representation according to a principle diagram at the level of a section AA of a salient pole of a first series of an example of the first embodiment.

[0035] [Fig.lD] shows a representation according to a principle diagram at the level of a section BB of a salient pole of a second series of an example of the first embodiment.

[0036] [Fig.2] shows a synchronous electrical machine according to a first example of a first embodiment comprising an inductor according to [Fig.1A].

[0037] [Fig.3] shows a synchronous electrical machine according to another example of the first embodiment comprising two inductors according to [Fig.1A].

[0038] [Fig.4]. shows an inductor without excitation coils according to an example of a second embodiment.

[0039] [Fig.5] shows the inductor of [Fig.4] comprises according to a second embodiment

[0040] [Fig.6] shows a synchronous electrical machine according to a second embodiment comprising an inductor according to [Fig.5].

[0041] [Fig.7] shows a block diagram of an example of an electrical machine according to a third embodiment comprising two inductors according to the first embodiment.

[0042] [Fig.8] shows a schematic diagram of a ferromagnetic rotor of an electric machine according to [Fig.7]. DETAILED DESCRIPTION

[0043] The figures are presented for information purposes only and in no way limit the invention.

[0044] A first aspect of the invention relates to an inductor I, F, an example of which first embodiment is shown in full in [Fig.1A] and in section in Figures 1B, 1D and another example of a second embodiment is shown partially and in full respectively in [Fig.4] and 1D. A second aspect of the invention relates to a single-layer axial flux synchronous electric machine M1, M1', M2, M3 each comprising at least one inductor I, F according to the first aspect of the invention. Different embodiments of single-layer axial flux synchronous electric machine M1, M1', M2, M3 are shown in Figures 2, 3, 6 and 7.

[0045] The inductor I, I' according to the first and second embodiments comprises a first series of salient poles 1 and a second series of salient poles 2 different from the first series of salient poles 1. In both embodiments, each salient pole 2 of the second series is located between two salient poles 1 of the first series. The salient poles 1, 2 of the two series are regularly distributed angularly around a central axis X. The inductor I, I' comprises a number Y of pairs of salient poles, equal to the number of pole 1 of the first series as well as to the number of salient poles 2 of the second series. The inductor I of the first embodiment comprises a number Y of pairs of poles equal to 5 and the number Y of pairs of poles in the inductor I' of the second embodiment is 7.Preferably, as shown in both embodiments, each salient pole 1 of the first series is identical to the ready manufacturing tolerances and each salient pole 2 of the second series is identical to the ready manufacturing tolerances in order to avoid unbalancing.

[0046] In both embodiments, each salient pole 1 of the first series comprises a ferromagnetic base 11 comprising a bare portion 1 In and a ferromagnetic nose 110 extending from the ferromagnetic base 11. The nose 110 comprises a radial surface of axial air gap 10.

[0047] In both embodiments, each salient pole 2 comprises a coil body 21 and an excitation coil 22 wound around at least a portion of the coil body 21, called the wound covered portion 210. Each salient pole 2. Each salient pole 2 comprises a radial axial air gap face 20.

[0048] In both embodiments, the inductor I, I' comprises notches 3. Each notch 3 houses an active part of the different excitation coils 22 of a salient pole 2 of a second series. Each notch 3 is formed between a coil body 21 of the salient poles 2 of the second series and a base 11 adjacent to one of the salient poles 1 adjacent to the first series. In other words, there is a number of notches equal to two Y, i.e. one notch 3 on each side of each coil body 21 and one notch 3 on each side of each base 11. By neighboring pole is meant the closest salient pole. The more active parts of the excitation coils 22 the notch 3 houses, the better the power of the isovolume machine. A slot fill % ratio is known to express the ratio of conductor volume (the active parts of the coil) in the slot volume 3.In both embodiments, each excitation coil 22 comprises turns wrapped around the covered wound portion 210 of the coil body 21. Each turn is one turn of the electrical conductor of the coil around the covered wound portion 210 of the coil body 21. Thus the coil is wound along an axis substantially parallel to the central axis X of the inductor I, I'. Each turn comprises two active parts each housed in a corresponding notch 3 on each side of the coil body 21. Each excitation coil 22 therefore comprises a first turn around and opposite (see in contact with) the wound covered part 210, having one end connected to a terminal of the inductor or to another excitation coil 22 and a last turn connected to a terminal of the inductor or to another excitation coil 22. The excitation coils can be electrically connected in parallel by connecting each end of the first turns together and each end of the last turns together. The excitation coils can also be electrically connected in series by connecting each end of the first turns to one end of a last turn of another excitation coil.According to the first aspect of the invention, each last turn of each excitation coil 22 of a salient pole 2 of a second series of the inductor I, I' according to the first and second embodiments is closer to the bare part 1 In of the base 11 of the second series of salient poles 1 than to the coil body 22 around which the last turn is wound. The last turn of each excitation coil 22 is closer to the bare part 1 In of the base 11 of the second series of salient poles 1 than to the first turn of the same excitation coil 22. This characteristic of the first aspect of the invention makes it possible to increase this slot filling % rate in two different ways, whether according to the first or second embodiment described below.

[0049] In particular in the inductor I of the first embodiment, as visible in particular in [Fig.lB] representing a radial section, that is to say in a plane perpendicular to the central axis, at the level of the excitation coils 22, only the salient poles 2 of the second series comprise an excitation coil 22 unlike the inductor I' of the second embodiment, as visible in [Fig.5], each salient pole 1, 2 of the first and second series of which comprises an excitation coil 12, 22 each wound around the base 11 or the coil body 21 but not at the same height as will be explained below.

[0050] According to one example, in the inductor I of the first embodiment, each excitation coil 22 is wound in the two notches 3 surrounding the corresponding coil body 21 by having its last turn in contact with the bare part 1 In of each base 11 of one of the two neighboring salient poles 1. This makes it possible to fill the conductor filling rate in the notch 3 to the maximum. According to another example, each excitation coil comprises its last turn distant from the bare part of each base of the two neighboring salient poles by a distance less than a diameter or a width or a length of a section of the conductor of the coil. According to yet another example, at least one excitation coil 22 comprises its last turn distant from the bare part of each base of the two neighboring salient poles and at least one other excitation coil 22 comprises its last turn in contact with the bare part lin of a base 11 of one of the two neighboring salient poles 1.Of course, according to . yet another example, the last turn of at least one excitation coil 22 can also be further away from the bare part 1 In of a base 11 of one of the two neighboring salient poles 1 than the diameter or the width or the length of a section of the conductor of the excitation coil 22.

[0051] The inductor I according to the first embodiment further comprises a frame 4 comprising an opening with a central axis X. The base 11 and the coil body 21 each extend from a radial face of the base 11 in a direction parallel to the central axis X.

[0052] In this example, each coil body 21 in particular visible according to [Fig.lD] schematically representing the axial section AA (section in a plane comprising the central axis X) in a salient pole 2 of the second series shown in [Fig.lA] is made of ferromagnetic material and is in this case identical to each base 11 of each salient pole 1 of the first series in particular visible according to [Fig.lC] schematically representing the axial section BB in a salient pole 1 of the first series shown in [Fig.lA]. By schematic representation of the axial section AA or BB it is meant that the dimensions are not respected. According to another example not shown, the coil body is made of plastic or composite and includes a central orifice to reduce the weight.

[0053] In this example, optionally, each salient pole 2 of the second series also comprises a ferromagnetic tip 212 extending from the coil body 21 to the radial face of the axial air gap of the salient pole 2. In other words, the radial face 20 comprises a radial surface 20 of the tip 212. In this example, each tip 212 is identical to the tip 110 of a salient pole 1 of the first series.

[0054] In this example, as can be seen in [Fig.lD], each excitation coil 22 completely covers the corresponding coil body 21 and therefore each covered wound part 210 completely forms the coil body 21 of the salient pole 2 of the second series.

[0055] Each bare part 1 In of a salient pole 1 of the first series of the inductor I of the first embodiment also entirely forms the ferromagnetic base 11 of the salient pole 1 of the first series.

[0056] In particular, in this example of this first embodiment, the inductor I comprises inter-pole magnets 7 each positioned between a tip 110 of a salient pole 1 of the first series and a tip 212 adjacent to a salient pole 2 of the second series at the level of the face and radial surface of the axial air gap.

[0057] Each magnet 7 comprises a first side having a first polarity, attached to a beak 110 of a salient pole 1 of the first series and its other side having a second polarity, attached to a beak 212 of the salient pole 2 of the second series. For example, the first polarity of each magnet is north and the second polarity is south, but this can be reversed, it all depends on the direction of the current and the direction of the winding of the excitation coils 22.

[0058] The inductor I also comprises an internal radius rl measured radially between an internal radial end of the beak 110 closest to the central axis X and an external radial end of the beak 110 furthest from the central axis X. Preferably the internal radius rl is equal to 60% + or - 20% of the external radius r2, here in this example this ratio rl / r2 is equal to 60% allowing the best optimization of the torque at iso external diameter.

[0059] In this example, the inductor I is intended to be part of a rotor of a synchronous electrical machine Ml, Ml' shown in Figures 2 and 3 and therefore to be mounted on a rotor shaft, a hoop 6 surrounds the poles 1, 2, while being in contact with an external circumference of these poles 1, 2. In this example, the hoop 6 is hooped (tightly mounted) against a circumferential surface of each beak 110, 212 thus surrounding the inter-pole magnets 7 to retain them radially against the centrifugal force as well as to prevent deformation of the poles 1, 2 in particular at the connection between the frame 4 and the bases 11 or the coil bodies 21.In this example, it can be seen that the excitation coils 22 comprise an inner (close to the central axis) and outer (furthest from the central axis) coil, the smallest radius of the inductor I of which is measured from the end of an inner coil closest to the central shaft and the largest radius of the inductor I of which is measured from one end of an outer coil furthest from the central shaft (or outer diameter measured between two outer ends of the outer coils of two excitation coils 22). Of course, according to another example, the frame 4 may have the largest outer diameter of the inductor, but the inductor would be heavier. In this example, the hoop 6 comprises an outer diameter between the outer diameter of the frame 4 and the outer diameter (2 * r2) of the salient poles 1, 2. The fret 6 may, according to another example, comprise a part forming an external housing surrounding the external coils of the coils on the external side..

[0060] According to another example not shown, the inductor is a damping squirrel cage inductor; in this example, each inter-pole magnet and the hoop are replaced by electrical conductors in the form of a bar and a ring respectively.

[0061] The axial flux synchronous machine M1 shown in [Fig.3] is according to an example of a first embodiment, without the representation of the rotor shaft, the hoop 6 and the interpolar magnets 7.

[0062] The rotor of the axial flux synchronous machine M1 further comprises the inductor I, a rotor shaft with a central axis X fixed to the frame 4 directly or indirectly, for example by a sleeve mounted tightly on the rotor shaft and against a circumferential peripheral surface 40 of the frame 4 visible in [Fig.2]. According to another example, the rotor shaft comprises a collar or a shoulder allowing to have an external circumferential external surface mounted tightly directly against the circumferential peripheral surface 40 of the frame 4. According to another example not shown, the frame 4 and the rotor shaft are made in one piece (molded or machined). According to yet another example, the hoop 6 of the rotor can surround the inductor I, cover the radial surface of the frame 4 opposite the salient poles 1, 2 and form the connecting piece between the rotor shaft (by being mounted for example tightly or other means of fixing (flange etc.) and the inductor I.

[0063] The axial flux synchronous machine M1 further comprises a lateral stator armature 5 comprising a winding comprising a number Pa of active parts, each in this case housed in a notch formed between two teeth of the armature 5. The teeth are distributed regularly angularly around the central axis C, i.e. the axis of rotation X, surrounding the rotor shaft (not shown). In this example, the number Pa of active parts is equal to 12 and the winding is a corresponding fractional concentric winding when a number of teeth of the armature divided by the number of phases and by the number of poles of the inductor is not an integer (or half-integer). In this case, this number is equal to 12 / 10 / 3 = 0.4." The armature may also comprise coil bodies each wound by a coil of the winding forming active parts distributed regularly angularly around the central axis C.

[0064] The armature 5 (explained in more detail in the third embodiment of the machine shown in [Fig.7]) comprises notches between each tooth and a winding comprising the active parts in notches. In this example, the winding is concentric but could be distributed, for example, undulated. The armature 5 may comprise, for example, three phases, but could comprise more. In this example, the armature 5 comprises a rear yoke 54 in a stack of laminations but could also be manufactured from compact magnetic iron powder. The teeth are in this example also ferromagnetic and preferably formed by a stack of laminations. In other words, the stator armature 5 is an armature comprising a wound winding 50 in a stack of laminations forming the teeth.

[0065] The coils are wound in notches in the sheet metal pack of the armature 5.

[0066] The armature 5 comprises an axial air gap radial face, here in this example facing the air gap surfaces 10 of the tips 110 of the salient poles 1 of the first series and the radial faces 20 (in this case a radial surface of the tip 212) of the salient poles 2 of the second series. In this embodiment, the axial flux gap is thus formed between the armature I and the inductor 5.

[0067] The second example of this embodiment of axial flux rotating electrical machine Ml' visible in [Fig.3] is different from the axial flux rotating electrical machine Ml in that it comprises two inductors I according to the first example of this embodiment and a central 5' induced.

[0068] In this second example, the rotor comprises the two inductors I and are coupled in rotation to a rotor shaft (not shown) according to one of the examples described previously.

[0069] The central stator armature 5' is different from the lateral stator armature 5 in that it does not have a yoke 54 but only a plurality of teeth forming notches between them and a winding 50 comprising active parts in notches. The coils can be held together using different manufacturing methods, for example by being embedded in resin, or the stator can comprise a cylindrical external yoke surrounding the armature 5' or an internal yoke surrounded by the winding 50.

[0070] In particular in this example, each tooth of the central stator armature 5' is ferromagnetic and comprises a first ferromagnetic radial surface forming together the first axial air gap radial face opposite the first armature I and a second ferromagnetic radial surface axially opposite the first radial surface, forming together a second axial air gap radial face opposite the second armature I.

[0071] In this second example, the two inductors I are fixed to the rotor while being angularly offset from each other by one pole such that each pole of a first series of one of the inductors I is axially aligned with a pole of a second series of the other inductor I.In other words, when the first radial surface of the armature 5, comprising a radial surface of each active part of the winding and in this case also that of each tooth or coil body of the armature 5, is opposite (as a function of the angle of rotation of the armature) an air gap surface 10 of a nose 110 of one of the salient poles 1 of the first series of the first armature I, the second radial surface of the armature 5 (also comprising a second radial surface of each active part of the winding and in this case also that of a tooth or coil body of the armature 5) is opposite a radial face 20 (in this case a radial surface of the nose 212) of one of the salient poles 2 of the second series of the second armature I (and conversely when the rotor rotates angularly by one pole either here 36° (180° / Y = 180 / 5 = 36°).This second example of this first embodiment of axial flux electric machine Ml' has a double advantage compared to that of the first example of the axial flux electric machine Ml, the first is to avoid even harmonics, the second is to balance the axial forces on the rotor making it possible to increase the life of the bearings (for example rollers) supporting the rotor shaft.

[0072] In these two examples of this embodiment, the rotor further comprises a power supply device (not shown) for the excitation coils 20 of the inductor I comprising a rotating part secured to the rotor shaft and electrically connected to the excitation coils 20 and a stator part secured in rotation to the stator armature. The ratio of r 1 / r2 equal to 60% + or - 20%, here equal to 60% makes it possible to have a radius rl of the inductor I, sufficiently large so that the rotating part secured to the power supply device is located axially between an axial end of the yoke of an armature in the case of the first example or of the frame 4 of the second inductor I in the case of the second example and an axial end of the frame 4 of the first inductor I.

[0073] In the various examples shown, the coil bodies are made of ferromagnetic material but could be made of paramagnetic or diamagnetic material.

[0074] The inductor I' according to the second embodiment is now described, in this case in this example it is a central inductor I' to be located between two lateral armatures 5, as shown in [Fig.6] representing an axial flux electric machine M2 according to a second embodiment comprising the inductor I' surrounded axially on either side by two lateral armatures 5 (whose winding is not shown).

[0075] [Fig.4] represents the inductor I' without excitation coil 20. As can be seen, this inductor i' is different on the one hand in that it is devoid of frame 4 and on the other hand in that each pole 1, 2 comprises: • a second radial air gap face 20' formed in this example by a radial air gap surface of a second nose 212' each extending from a coil body 21 opposite the first nose 212 and • a second radial axial air gap surface 10' formed in this example by a second beak 110' each extending from a base 11 opposite the first beak 110 forming the first radial axial air gap surface 10 opposite the first radial axial air gap surface.

[0076] In this example, the two air gap faces of the inductor F are identical to that of the inductor I except, as already stated, that it comprises 7 pairs of poles. In this case, inductor I' further comprises, on its other face, inter-pole magnets 7' between each salient pole 1, 2 and a second hoop 6' surrounding the second tips 110', 212'.

[0077] In this figure, there is also shown a section of a section at the level of a collar 8 of a rotor shaft.

[0078] [Fig. 5] represents a schematic diagram according to a perspective view of the second face of the inductor I' of [Fig. 4] (with a different angle of rotation along the central axis X) with the excitation winding which is different from that of the first embodiment in that it comprises an excitation coil 12 per salient pole 1 of the first series. Each base 11 therefore further comprises a bare part 1 In a second covered part wound 11' (referenced on [Fig.4]).

[0079] In this second embodiment, each excitation coil 12 is therefore wound around the second covered wound part 11' of the ferromagnetic base 11 extending from the first bare part lin.

[0080] Furthermore, each coil body 21 comprises a bare portion 21n extending from the wound covered portion 210. Each excitation coil 12 wound around a second wound covered portion 11' of the ferromagnetic base 11 of each pole 1 of the first series has a last turn closer to the two neighboring bare portions 21n of the two neighboring coil bodies 21 of each neighboring salient pole 2 than to the second wound covered portion 210 of this coil body 21 around which it is wound.

[0081] Thus, each notch 3 has two halves of axial volume divided in two by a radial median plane perpendicular to the axis of rotation, the first half of which houses the active parts of the excitation coil 12 of a salient pole 1 of a first series and the second half of the volume houses the active parts of the excitation coil 22 of a salient pole 2 of a second series. The filling rate can thus be greater than in the case of the prior art where each coil of each pole of the first series completely surrounds the entire axial length of the corresponding base (no bare part) and each other coil of each pole of the second series completely surrounds the entire axial length of the corresponding coil body. Indeed, in the prior art, the active parts of each coil of each pole are housed in each notch opposite the active parts of the neighboring coil, producing an unfilled gap in the notch.Indeed, in the prior art, each coil comprises its active parts in a circumferential half of the volume defined by a plane passing through the axis, whereas in this embodiment they are located in an axial half of the volume of the notch defined by a plane perpendicular to the axis, making it possible to dispense with the gap (indeed, the excitation coils 12, 22 can be in contact with each other in the notch 3).

[0082] The filling rate of the active part per notch is therefore close to 100% (unattainable due to the insulation between each conductor and the space formed between each turn).

[0083] According to another embodiment of inductor not shown identical to this second embodiment, except in that the inductor is a lateral inductor comprising in place of the second radial face, a frame replacing the hoop, the interpolar magnets and the tips of the salient poles of the two series. Thus this lateral inductor is like the lateral inductor I of the first embodiment except in that the winding is like that of the second embodiment.

[0084] [Fig.6] represents the axial flux synchronous electric machine M2 according to a second embodiment comprising the inductor I' shown in [Fig.5]. This axial flux synchronous electric machine M2 comprises a second stator armature 5 identical to the first stator armature 5 of the electric machine M1 of the first example of the first embodiment except that the stator armature comprises 7 pairs of poles. In this [Fig.6], the winding of each stator armature 5 has not been shown. The central inductor I' is located axially between the two armatures 5 comprising a cylindrical yoke 54 and poles each formed by a ferromagnetic base 51 extending axially from a radial face of the yoke 54 and a ferromagnetic nose 510 extending from the base towards the central inductor F.

[0085] [Fig.7] represents a schematic diagram of an axial section (comprising the axis of rotation) of an axial flux synchronous electric machine M3 according to a third embodiment. In this figure, being a schematic diagram, the length ratio, for example rl / r2 is not shown.

[0086] The axial flux synchronous electric machine M3 comprises two lateral inductors I according to the first embodiment and a central armature 5' as in the axial flux synchronous electric machine Ml' according to the second example of the first embodiment. The two lateral inductors I are shown schematically but are like those of the axial flux synchronous electric machine Ml' except that the two lateral inductors I are statoric, that is to say integral in rotation with the armature 5 and not with the rotor shaft.

[0087] The axial flux electrical machine M3 comprises a ferromagnetic rotor 9 comprising a rotor shaft 91 and a first and a second set 90, 90' of ferromagnetic parts 93, preferably identical, integral in rotation with the rotor shaft 91. The first set 90 of ferromagnetic parts 93 is shown in [Fig.8]. The first and second sets 90, 90' of ferromagnetic parts 93 each comprise a ring 92 integral with the rotation shaft 91 of the rotor 9 and a number Ns of ferromagnetic parts 93 regularly distributed around the central axis X, each fixed to the ring 92. The ring 92 may be made of plastic or composite, for example.The number Ns is equal to the sum of or the difference between Pa / 2 and Pe / 2, the first set 90 of ferromagnetic parts 93 is located between the first stator inductor I and the central stator armature 5, while the second set 90 of ferromagnetic parts 93 is located between the second stator inductor I and the central stator armature 5. The first set 90 of ferromagnetic parts 93 comprises a first radial axial air gap face facing the radial air gap face of the first armature I. The second set 90' of ferromagnetic parts 93 comprises a second radial axial air gap face facing the radial air gap face of the second armature I. As a reminder, the radial air gap face of each armature I comprises the radial axial air gap face 20 of the salient poles 2 of the . second series, in this example a radial surface of the nose 212 as well as the radial surface of the axial air gap of the nose 110 of the salient poles 1 of the first series.

[0088] the two inductors I are integral with each other while being angularly offset from each other by one pole such that each pole of a first series of one of the inductors I is axially aligned with a pole of a second series of the other inductor I. In this [Fig.7], we can see a salient pole 2 of the second series of the first armature I axially aligned with salient pole 1 of the first series of the second armature, as well as a salient pole 1 of the first series of the first armature I axially aligned with a salient pole 2 of the second series of the second armature I.

[0089] In this example, the coil bodies 51 of the armature 5 are symmetrical and comprise a base 510 and a first 512 and a second nose 512' axially opposite one another extending from the base 510. The base 510 with the first nose 512 and the second nose 512' form between them a notch housing the winding 50, for example a concentric coil per pole. In other words, in this axial flux electric machine M3, the first nose 512 of the central armature 5 comprises a first radial axial air gap surface facing a second radial axial air gap face of the first set 90 of ferromagnetic parts 93 and the second nose 512' of the central armature 5 comprises a second radial axial air gap surface facing a first radial axial air gap face of the second set 90' of ferromagnetic parts 93.

[0090] The coils in the different embodiments each comprise an electrical conductor, for example made of copper, and an insulator making it possible to isolate the conductor from one turn to another turn or from one coil to another coil or from the coil to a ferromagnetic part (base, nozzle or coil body or even frame, yoke, etc.).

[0091] In the various embodiments of the various machines, the rotor shaft may comprise a cooling channel comprising an axial duct extending axially in the rotor shaft, an opening in the axial duct to receive a cooling fluid such as oil and at least one projection duct extending from the axial duct to an opening on the circumference of the rotor shaft opposite a coil of the armature or the inductor.

[0092] Unless otherwise specified, the same element appearing in different figures has a single reference.

Claims

Claims

1. Inductor (I, I') of an axial flux synchronous electric machine (Ml, Ml', M2, M3) the inductor (I, I') being of the salient pole type comprising: • a first series of salient poles (1) each comprising a ferromagnetic base (11) regularly distributed angularly around a central axis (X), and a beak (110) extending from the ferromagnetic base (11) comprising a radial surface of axial air gap (10), each ferromagnetic base (11) comprising at least one bare part (lin), • a second series of salient poles (2), each located between two salient poles (1) of the first series, each salient pole (2) of the second series comprising at least:

1. a coil body (21) comprising a wound covered part (211), 2. an excitation coil (22) wound around the wound covered part (210) of the coil body (21), 3. an axial air gap radial face (20). • notches (3), each formed between a coil body (21) of the salient poles (2) of the second series and a base (111) adjacent to one of the salient poles (1) adjacent to the first series • characterized in that each excitation coil (22) of the second series of salient poles (2) comprises turns surrounded around the covered wound part (210) of the coil body (21) forming active parts in at least a part of each notch (3) on each side of the coil body (21) formed with the bare part (1 In) of the base (11) of a salient pole (1) neighboring the first series, such that the last turn is closer to each of the two bare parts (1 In) of the two bases (11) neighboring the salient pole (1) of the first series, than to the coil body (21).

2. An inductor (I, I') of an axial flux synchronous electrical machine (Ml, Ml', M2, M3) according to claim 1 further comprises inter-pole magnets (7) positioned between each salient pole (1) of the first series and each salient pole (2) of the second series at the face and radial surface of axial air gap (10, 20).

3.

4.

5. Inductor (I') of a synchronous electrical machine (M2) according to one of the preceding claims in which: each coil body (21) comprising a bare portion (21n) extending from the covered wound portion, each ferromagnetic base (11) of a salient pole (1) of the first series comprises a second covered wound part (11') extending from the first bare part (1 In), and in that each salient pole (1) of the first series comprises an excitation coil (12) wound around the second covered wound part (11') having a last turn closer to each bare part (21n) neighboring the coil body (21) of the two salient poles (1) neighboring the first series than to the second covered wound part (H'). Inductor (I') of a synchronous electric machine according to the res indication 3, in which the inductor (I') is a central inductor in which: the coil bodies (21) are each ferromagnetic and each comprise a first radial axial air gap surface (10) and the ferromagnetic bases (11) and the coil bodies (21) each comprise a second axial air gap radial surface (20', 10') opposite the first axial air gap radial surface (10, 20). Inductor (I) of a synchronous electric machine (Ml, Ml') according to one of claims 1 to 4, wherein the inductor is a single-layer lateral inductor comprising a ferromagnetic frame (4) comprising a face radial with respect to the central axis (X), each salient pole (1) of the first series extending axially from the radial face of the ferromagnetic frame (4) comprising only the bare part (lin) extending from the frame (4) to the beak (110) and - each coil body of the second series extending axially from the radial face of the ferromagnetic frame comprising only the covered wound portion (210) of the coil body (21) extending axially from the frame, the excitation coil entirely surrounding only the covered wound portion (210).

6. Axial flux synchronous electrical machine (Ml, Ml', M2, M3) comprising an inductor (I, I') according to one of the preceding claims, comprising: - a rotor shaft having an axis of rotation (X) corresponding to the central axis (X), - a stator armature (5, 5') comprising: • a winding (50) comprising a number Pa of active parts regularly angularly distributed around the axis of rotation (X) surrounding the rotor shaft, • a radial face of axial air gap.

7. Axial flux synchronous electrical machine according to claim 6 in which the inductor (Ml, Ml', M2) is integral with the rotor shaft and together forms a rotor, each axial air gap radial surface being opposite the axial air gap radial face of the armature (I, I') forming an axial air gap between them.

8. Axial flux synchronous electric machine (Ml, Ml', M2) according to claim 7 wherein the rotor further comprises a hoop (6) surrounding and in contact with the poles of the inductor (I, I').

9. A compact axial flux electric machine according to claim 8, wherein the hoop comprises a housing receiving a portion of the winding, the housing having a diameter external to the diameter of the inductor.

10. Compact axial flux electric machine according to one of the preceding claims 7 to 9, in which: - the inductor comprises an internal radius (rl) and an external radius (r2) measured radially respectively between an internal radial end of the nose (110) closest to the central axis (X) and an external radial end of the beak (110) furthest from the central axis (X) and in that the internal radius (rl) is equal to 60% + or - 20% of the external radius (r2) and - the rotor further comprises a device for supplying the excitation coils (20) of the inductor comprising: • a rotary part secured to the rotor shaft and electrically connected to the excitation coils (20), being located axially between an axial end of an armature (5) or inductor (i) and an axial end of another armature or another inductor axially opposite this axial end, • a stator part secured in rotation to the stator armature.

11. Axial flux synchronous electrical machine (M3) according to claim 8 wherein the inductor (I) is stator surrounding the rotor shaft (9), the machine further comprising a ferromagnetic rotor (90) comprising the rotor shaft (9) and a first set (90) of ferromagnetic parts (93) comprising a number Ns of parts regularly distributed around the axis of rotation (X), the number Ns is equal to the sum of or the difference between Pa / 2 and Pe / 2, the set (90) of ferromagnetic parts (93) being located between the first stator inductor (I) and the first stator armature (5).

12. Axial flux synchronous electric machine (Ml', M3) according to one of the preceding claims 6 to 11 comprising a second inductor (I) according to claim 5 identical to the first inductor, the armature (5) being a central armature (5) located axially between the two inductors (I), the armature (5) comprising a second radial axial air gap face per tooth, and the two inductors are angularly offset from each other by one pole such that each pole of the second series of one of the inductors is axially aligned with a pole of the first series of the other inductor.

13. An axial flux electric machine according to the preceding claim, wherein the inductor is according to claim 2 and in that each magnet of the first inductor has a polarity opposite to the polarity of an axially aligned magnet of the second inductor.

14. Axial flux machine (M2) according to one of the preceding claims 6 to 12 comprising a second stator armature (5) identical to the first stator armature (5), the inductor (!') being according to claim 3 or 4 and being a central inductor located axially between the two armatures (5), each armature (5) comprising a yoke and teeth extending from the yoke towards the central inductor forming between them notches of the number Pa each housing an active part.

15. A compact axial flux electrical machine according to one of the preceding claims 6 to 14, wherein the rotor shaft further comprises a cooling channel comprising an axial duct extending axially in the rotor shaft and at least one projection duct extending from the axial duct to an opening opposite a coil of the armature or the inductor.

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