N-phase electric machine

Abstract

The invention relates to an N-phase electrical machine comprising a moving member (1) equipped with an encoder (3) having a track (5) formed of magnetic poles, a fixed ferromagnetic armature (7) equipped with a circuit (12) forming coils (9) electrically connected to a power supply system (2) and magnetically coupled to the track (5), and ferromagnetic pads (8) surrounded by the coils (9) such that the power supply to the coils (9) induces the movement of the encoder (3) and / or the movement of the encoder (3) induces said power supply. The moving member (1) and the armature (7) each have a peripheral ring (1c, 7c) arranged radially opposite each other to form an annular space in which a bearing (14) is mounted. This bearing comprises two rings (16, 15), each rotationally fixed to a ring (1c, 7c), and mounted for relative rotation to guide the moving member. (1). Figure 4a

Description

Title of the invention: N-phase electric machine

[0001] The invention relates to an N-phase electrical machine comprising a mobile member mounted in rotation relative to a fixed member and an electrical power supply system.

[0002] Such a machine may further comprise a system for determining at least one item of information relating to the movement of the moving member, in order to be able to manage the electrical power supply system by means of said information.

[0003] In a particular application, the machine is powered with electricity to actuate the movement drive of the movable member, for example for the purpose of motorizing a motor vehicle actuator. In another application, the machine operates as a generator and produces electricity by moving the movable member in order to be able to power the system.

[0004] In particular, electrical machines of the permanent magnet synchronous electric motor type are known in which the fixed member has an armature made of ferromagnetic material which is equipped with a printed circuit forming at least one conductive coil per phase, the mobile member being integral in movement with at least two North and South magnetic poles.

[0005] In this type of electrical machine, it may be desired to know in real time and with optimal reliability at least one piece of information relating to the movement of the moving member, for example a parameter such as its position, its speed, its acceleration or its direction of movement, in particular in order to be able to control the electrical supply of a driving machine and / or control the electricity supplied by a generating machine.

[0006] To do this, electrical machines are known which are equipped with a determination system comprising an encoder secured to the moving member which is capable of generating a signal representative of its movement, and a sensor secured to the fixed member which is capable of determining said information by reading the signal generated by said encoder.

[0007] According to an embodiment allowing optimal resolution of the determined information, the encoder has a magnetic track formed from a succession of pairs of North and South magnetic poles which are arranged to deliver a pseudo-sinusoidal magnetic field, the sensor comprising at least two sensitive elements arranged at a reading distance from the magnetic track of the encoder.

[0008] Document FR-3 114 454 proposes an electrical machine in which the functions of electrical power supply and determination of at least one item of information relating to the movement of the moving member are carried out jointly, in particular in order to avoid indexing of the moving member with the encoder allowing said determination. mination.

[0009] To do this, this document proposes an electrical machine in which: - the encoder has a magnetic track formed from a succession of npp pairs of North and South magnetic poles of width Lp which are arranged to deliver a pseudo-sinusoidal magnetic field; - the coils are electrically connected to the power supply system by being magnetically coupled to the encoder track; - the armature comprises pads around which a coil is respectively arranged.

[0010] In particular, the pads each have a free surface arranged opposite the magnetic track in order to direct the magnetic flux between the coil and the encoder so that the electrical supply of the coils induces the movement of the encoder and / or so that the movement of the encoder induces the electrical supply of said coils. In particular, the free surface may have teeth of width Ld spaced by hollows of width Le, the widths Ld and / or Le being such that their ratio to N.LP is not even or inversely even.

[0011] According to known embodiments, the movable member has a central axis which is mounted in rotation in a bore of the fixed member, in particular by means of two bearings which are axially superimposed along said axis.

[0012] Indeed, given the small diameter of the shaft and the importance of controlling the clearance between the studs and the magnetic track for proper operation of the machine, the two bearings are necessary to limit the tilting of the moving member and therefore its detrimental impact on the stability of said clearance.

[0013] However, this solution increases the axial dimension of the machine, in particular compared to an embodiment in which a single bearing would be sufficient to guarantee the stability of the rotation of the moving member.

[0014] The invention aims to improve the prior art by proposing in particular an electrical machine in which the mobile member is mounted in rotation while limiting the risks of tilting, while limiting the axial dimension necessary to install said mounting in rotation.

[0015] To this end, the invention proposes an N-phase electrical machine comprising a mobile member mounted in rotation relative to a fixed member and an electrical power supply system, said mobile member being equipped with an encoder having a magnetic track formed of a succession of npp pairs of North and South magnetic poles of width Lp which are arranged to deliver a pseudo-sinusoidal magnetic field, the fixed member comprising an armature made of ferromagnetic material which is equipped with a printed circuit forming at least one conductive coil per phase, said coils being electrically connected to the power supply system by being magnetically coupled to the encoder track, said fixed member comprising studs made of ferromagnetic material around which a coil is respectively arranged, said studs having a free surface arranged opposite the magnetic track in order to direct the magnetic flux between the coil and the encoder so that the electrical supply of the coils induces the movement of the encoder and / or so that the movement of the encoder induces the electrical supply of said coils, the movable member - respectively the armature - having an outer peripheral crown - respectively an inner one -, said crowns being arranged radially opposite each other to form between them an annular space in which a bearing is mounted, said bearing comprising an inner ring integral in rotation with the outer crown and an outer ring integral in rotation with the inner crown,said rings being mounted in relative rotation to guide the rotation of the movable member relative to the fixed member.

[0016] Other features and advantages of the invention will appear in the following description, given with reference to the attached figures, in which:

[0017] [Fig. 1] is a schematic representation showing in exploded perspective a electric machine according to one embodiment of the invention;

[0018] [Fig.2] represents the arrangement of the encoder relative to the teeth of a pad in a electric machine according to the invention;

[0019] [Fig.3] is a schematic perspective representation of the fixed organ assembly / rolling bearing of the electric machine of [Fig.l];

[0020] [Fig.4a] and

[0021] [Fig.4b] are assembled schematic representations and in axial section of the electric machine of [Fig.l], respectively in perspective ([Fig.4a]) and in front view ([Fig.4b]);

[0022] [Fig.5] is a schematic representation in perspective seen from below of the electric machine of the previous figures.

[0023] In relation to these figures, an N-phase electrical machine is described comprising a mobile member 1 mounted to move relative to a fixed member, N being an integer greater than 1, in particular in relation to a two-phase or three-phase electrical machine.

[0024] According to one application, the machine is powered with electricity to actuate the movement drive of the movable member 1, for example for the purpose of motorizing a motor vehicle actuator. In particular, the electrical machine may constitute a permanent magnet synchronous motor. In another application, the machine operates as a generator and produces electricity by moving the movable member 1.

[0025] The electrical machine comprises an electrical power supply system 2 which is managed For : - in the case of a driving machine, being able to control the movement of the moving part 1, in particular in relation to the torque and the speed of movement; and / or - in the case of a generator machine, check its power supply, particularly in relation to the frequency of the electrical voltage generated.

[0026] According to one embodiment, the electrical machine comprises a system for determining at least one item of information relating to the movement of the mobile member 1, in particular arranged to deliver information relating to the position of said mobile member, said information being used by the power supply system 2 for its management. The information determined may also relate to the speed, acceleration and / or direction of movement of the mobile member 1.

[0027] The determination system comprises: - an encoder 3 equipping the movable member 1, so as to be integral in movement with said movable member, said encoder being capable of generating a signal representative of its movement; and - a sensor 4 secured to the fixed member which is capable of determining the information by reading the signal generated by said encoder.

[0028] According to an embodiment allowing optimal resolution of the determined information, the encoder 3 has a magnetic track 5 formed of a succession of npp pairs of magnetic poles 6 North and South of width Lp which are arranged to deliver a pseudo-sinusoidal magnetic field, the sensor 4 comprising at least two sensitive elements arranged at a reading distance from the magnetic track 5 of the encoder 3.

[0029] According to one embodiment, known in particular from document EP-1 403 622, the encoder 3 may have a secondary magnetic track making it possible in particular to determine absolute position information. In particular, the two-track nature of the encoder 3 makes it possible to generate a reference pulse per pair of poles of a motor, which makes it easier to control it.

[0030] By way of example, the encoder 3 is formed from a magnet on which the magnetic poles 6 are constituted, in particular by forming at least one magnetized track 5. In particular, the magnet may comprise a matrix, for example made from a plastic or elastomer material, in which magnetic particles are dispersed, in particular particles of ferrite or rare earths such as NdFeB, which are magnetized according to the succession of poles 6.

[0031] Advantageously with respect to the resolution of the information delivered, the width Lp of each of the magnetic poles 6 of the encoder 3 is between 0.5 and 20 mm, the number npp of pairs of magnetic poles 6 of the encoder 3 being able to be at least equal to 2, in particular when being greater than 6.

[0032] The sensitive elements of the sensor 4 are each capable of emitting a signal which is a function of the field delivered by the track 5, the determination system comprising: - a device for processing the signals emitted by the sensitive elements which is arranged to provide two signals in quadrature and of the same amplitude which are each representative of the magnetic field; - from said quadrature signals, a device for calculating information relating to the movement of the moving member.

[0033] According to one embodiment, document WO-2006 / 064169 describes a sensor 4 arranged to deliver two signals respectively SIN and COS in quadrature and of the same amplitude which are each representative of the magnetic field delivered by track 5.

[0034] In particular, the sensor 4 may comprise at least one sensitive element, notably chosen from magnetosensitive probes, for example Hall effect probes, and / or probes based on tunnel magnetoresistances (TMR), anisotropic magnetoresistances (AMR) or giant magnetoresistances (GMR).

[0035] Furthermore, the calculation device may comprise interpolation means making it possible to increase the resolution of the information relating to the movement of the encoder 3.

[0036] The fixed member comprises a frame 7 made of ferromagnetic material. In the figures, the frame 7 comprises a discoidal bottom 7a which is bordered by an axial annular rim 7b, said annular rim having an axial inner wall 13 which forms an inner peripheral crown 7c.

[0037] The machine comprises pads 8 made of ferromagnetic material which protrude into the interface with the encoder 3, each having a head 8a whose free surface is arranged opposite the magnetic track 5. The air gap distance between the free surface of the pads 8 and the track 5 of the encoder 3 is of the order of 1 mm at most for a ferrite-based magnet and can be up to 10 mm for a rare earth-based magnet.

[0038] The movable member 1 may be formed by stamping a sheet of metallic material, and comprises a disc 1a whose periphery has an axial fold 1b which has an outer peripheral surface on which an outer peripheral crown 1c is formed.

[0039] The crowns 1e, 7c are arranged radially opposite each other to form between them an annular space in which a bearing 14 is mounted, said bearing comprising an inner ring 16 integral in rotation with the outer crown 1e and an outer ring 15 integral in rotation with the inner crown 7c, said rings being mounted in relative rotation to guide the rotation of the movable member 1 relative to the fixed member.

[0040] In the description, the terms of positioning in space are taken with reference to an axis of relative rotation of the movable member 1 with respect to the fixed member (vertical in FIGS. 1, 3, 4a and 4b). Thus: - the terms “axial” and “radial” refer to directions respectively following this axis and moving away from or towards it; - the terms “exterior” and “interior” refer to arrangements respectively close to and far from this axis.

[0041] This arrangement makes it possible, by offsetting the rotational guidance of the movable member 1 to the outer periphery of said member, to achieve said guidance along an increased diameter. Thus, the guidance can be achieved with a single bearing 14 while ensuring good stability of the rotation of the movable member 1, in particular by reducing the risks of tilting relative to the fixed member.

[0042] In the embodiment shown, the bearing 14 comprises a row of rolling bodies, in particular in the form of balls 17, which is arranged between the rings 15, 16 to guide their relative rotation.

[0043] The outer ring 1e has an axial outer wall 18 which is fitted onto an axial inner wall 16a of the inner ring 16.

[0044] Similarly, the inner crown 7c has an axial inner wall 13 in which an axial outer wall 15a of the outer ring 15 is fitted.

[0045] The movable member 1 has a central bore 19 in which a coupling interface 20 is associated, as well as an internal face 21 on which the encoder 3 is associated.

[0046] In the figures, the disc 1a has an inner plate 22 and an outer plate 23 connected by an external elbow 24 arranged to raise said outer plate, and such that: - the encoder 3 is associated on an internal face 21 of said internal plate; - the bore 19 is formed in the center of said inner plate; and - fold 1b is formed on the periphery of said outer plate.

[0047] In particular, this embodiment makes it possible to position the encoder 3 as axially as possible to the pads 8, while benefiting from a fold 1b of sufficient axial dimension to make the mounting of the bearing 14 more reliable.

[0048] The armature 7 is equipped with a printed circuit 12 forming at least one conductive coil 9 per phase, so that respectively a coil 9 is arranged around a pad 8, said coils being electrically connected to the power supply system 2 while being magnetically coupled to the track 5 of the encoder 3.

[0049] Thus, the encoder 3 is used as a permanent magnet for the operation of the electrical machine, in particular by delivering a magnetic flux, which makes it possible to combine, with the same means, the performance of the electrical power supply functions and determining at least one item of information relating to the movement of the moving member 1. Furthermore, when the encoder 3 has a secondary magnetic track, this also participates in the operation of the machine.

[0050] In particular, the power supply system 2 is capable of using the information delivered by the determination system to control the movement of the mobile member 1 and / or to control its electrical supply by the coils 9.

[0051] A coil 9 and a pad 8 per electrical phase can be provided. According to another embodiment, several coil 9 - pad 8 assemblies per electrical phase can be provided.

[0052] According to the embodiment shown, the encoder 3 has an annular magnetic track 5 which is integral with a rotating mobile member 1. In particular, the coils 9 of the phases can be distributed angularly in an alternating manner around the track 5 of the encoder 3 by being electrically connected in series and / or in parallel.

[0053] According to one embodiment, the electrical machine has three phases and a coil 9 - pad 8 assembly per phase, the phases consisting of one or more coils 9 being arranged at substantially 120° from each other.

[0054] According to one embodiment, it is possible to provide for operation of the electrical machine with standard management of the power supply system 2, the geometric center of a coil 9 of one phase being angularly spaced from the geometric center of a coil 9 of another phase by an integer multiple of an angle between:

[0055] 907N.npp and 2707N.npp for N=2; and

[0056] 2707N.npp and 4507N.npp for N>2.

[0057] In particular, the geometric center of a coil 9 of one phase is angularly spaced from the geometric center of a coil 9 of another phase by an integer multiple of an angle between:

[0058] 1357N.npp and 2257N.npp for N=2; and

[0059] 3157N.npp and 4057N.npp for N>2.

[0060] According to one embodiment, the geometric center of a coil 9 of one phase is angularly spaced from the geometric center of a coil 9 of another phase by an integer multiple of an angle of the order of 1807N.npp for N= 2 and 3607N.npp for N> 2, with an angle tolerance of + / - 50%.

[0061] In relation to the figures, the free surface of each of the pads 8 may have teeth 10 of width Ld spaced by hollows 11 of width Le, the widths Ld and / or Le being such that their ratio to N.LP is not even or inversely even (that is to say that the ratio Le / N.LPP or Ld / N.LPP is not equal to 2, 4 ... or to U2, %, ...) in order to direct the magnetic flux between the coil 9 and the encoder 3 so that the electrical supply of the coils 9 induces the movement of the encoder 3 and / or that the movement of the encoder 3 induces the electrical supply of said coils.

[0062] In particular, the teeth 10 channel the magnetic flux successively opposite the poles 6 of the same polarity, which creates a relative displacement force between the armature 7 and the encoder 3 secured to the mobile member 1, said force inducing the displacement of said mobile member in a driving machine or an electric current in the coils 9 of a generating machine.

[0063] Thus, thanks to the presence of these tooth 10 - hollow 11 assemblies, the magnetic flux density useful for the operation of the electrical machine is increased, in order to be able to use magnetic poles 6 of width Lp sufficiently reduced for the resolution of the determined displacement information, and this without requiring mechanical indexing since the magnetic operation of the machine is conferred by the encoder 3 which allows the determination of said information.

[0064] Advantageously, the width Ld of the teeth 10 is analogous to the width Le of the hollows 11. Furthermore, the ratio of the width Ld of the teeth 10 and / or the width Le of the hollows 11 to N.LP may be, at a manufacturing tolerance of + / - 40%, unitary or fractional.

[0065] To improve the magnetic coupling, the depth of the recesses 11 must be as great as possible, in particular by being greater than or equal to the width Ld of the teeth 10. To take into account manufacturing constraints, the depth of the recesses 11 can be of the order of magnitude of the width Ld of the teeth 10.

[0066] According to an advantageous embodiment, the coils 9 are each formed from several layers of printed circuit 12 comprising at least one conductive turn, said turns being connected to each other to form the coils 9.

[0067] Thus, the coils 9 have a reduced thickness which is favorable to the compactness of the machine, in particular compared to a conventional winding with a copper wire of a machine of equivalent power. In addition, great robustness of the winding is obtained and a simplified production in comparison with the need for a special machine for winding copper wires.

[0068] In particular, the printed circuit 12 may comprise an alternating stack of layers comprising at least one turn of electrically conductive material, for example copper, and insulating layers.

[0069] Advantageously, the determination system, as well as the system for controlling the moving member 1 and / or for controlling the electrical power supply are integrated on the printed circuit 12 of the stator of the machine, which makes it possible to greatly save space and eliminate the need for connections to an external control system.

[0070] In relation to the figures, the studs 8 are arranged in axial projection from the bottom 7a of the frame 7, in particular by being formed in a single piece with said bottom, and the printed circuit 12 has conduits 25 in which respectively a pad 8 is arranged with the coil 9 wound around said pad, said pads being associated with said printed circuit and / or with the armature 7 ensuring their magnetic coupling with said armature.

[0071] Advantageously, the axial stacking of the printed circuit 12 on the armature 7 to form the stator of the machine remains compact, the encoder 3 forming the rotor being arranged axially above said printed circuit to form an axial magnetic flux machine in which the sensor 4 axially reads the information delivered by said encoder.

[0072] In particular, an encoder 3 with an axial magnetic track 5 is simpler to manufacture than its equivalent with radial reading. Advantageously, the encoder 3 is made of elasto or plasto-ferrite, which allows great flexibility to quickly choose the number of pairs of poles 6 depending on the application.

[0073] In relation to figures 1, 3, 4a and 4b, the printed circuit 12 and the movable member 1 are stacked axially on the bottom 7a of the frame 7, and the annular rim 7b has a height which is sufficient to house said printed circuit and said movable member inside said frame.

[0074] Furthermore, as shown in Figures 4a and 4b, the free surface of the heads 8a of the pads 8 forms with the magnetic track 5 an axial clearance 29 which is arranged axially inside the bearing 14.

[0075] The printed circuit 12 has a discoidal geometry complementary to that of the base 7a, to which it is fixed in particular by means of rivets 26. Furthermore, the base 7a has an opening 27 through which a connection 28 of the printed circuit 12 is accessible.

[0076] Advantageously, the sensor 4 and the coils 9 are located on the upper surface of the printed circuit 12, so as to define the relative position between the sensitive elements of said sensor and said coils. In particular, the sensor 4 and the coils 9 can be arranged in the same plane parallel to the surface of the encoder 3, in particular to facilitate the production of the printed circuit 12.

[0077] As shown in particular in Figures 4a and 4b, the heads 8a of the pads 8 have a geometry similar to that of a section of magnetic track 5 of the encoder 3, the free surfaces of each pad 8 being able to further have a plurality of teeth 10 which extend radially.

[0078] Advantageously, the heads 8a have a maximum dimension along the magnetic track 5, as well as a maximum radial dimension, which are sufficiently large to optimize the magnetic interference zone between the pads 8 and said magnetic track.

Claims

Claims

1. N-phase electrical machine comprising a mobile member (1) mounted in rotation relative to a fixed member and an electrical power supply system (2), said mobile member being equipped with an encoder (3) having a magnetic track (5) formed of a succession of npp pairs of magnetic poles (6) North and South of width (Lp) which are arranged to deliver a pseudo-sinusoidal magnetic field, the fixed member comprising an armature (7) made of ferromagnetic material which is equipped with a printed circuit (12) forming at least one conductive coil (9) per phase, said coils being electrically connected to the power supply system (2) by being magnetically coupled to the track (5) of the encoder (3), said fixed member comprising pads (8) made of ferromagnetic material around which respectively a coil (9) is arranged,said pads having a free surface arranged opposite the magnetic track (5) in order to direct the magnetic flux between the coil (9) and the encoder (3) so that the electrical supply of the coils (9) induces the movement of the encoder (3) and / or that the movement of the encoder (3) induces the electrical supply of said coils, said machine being characterized in that the movable member (1) - respectively the armature (7) - has an outer peripheral crown (le) - respectively an inner crown (7c) -, said crowns being arranged radially opposite each other to form between them an annular space in which a bearing (14) is mounted, said bearing comprising an inner ring (16) integral in rotation with the outer ring (le) and an outer ring (15) integral in rotation with the inner ring (7c), said rings being mounted in relative rotation to guide the rotation of the movable member (1) relative to the fixed member.,

2. Electrical machine according to claim 1, characterized in that the outer ring (le) has an axial outer wall (18) which is fitted onto an axial inner wall (16a) of the inner ring (16).

3. Electrical machine according to one of claims 1 or 2, characterized in that the movable member (1) comprises a disc (1a) whose periphery has a radial fold (1b), the outer ring (1c) being formed as an outer periphery of said fold.

4. Electrical machine according to claim 3, characterized in that the disc (la) has an inner plate (22) and an outer plate (23) connected by an external elbow (24) arranged to raise said outer plate, the encoder (3) being associated on an internal face (21) of said inner plate and the fold (1b) being formed on the periphery of said outer plate.

5. Electrical machine according to any one of claims 1 to 4, characterized in that the bearing (14) comprises a row of rolling bodies (17) arranged between the rings (15, 16) to guide the relative rotation of said rings.

6. Electrical machine according to any one of claims 1 to 5, characterized in that the free surface of the pads (8) forms with the magnetic track (5) an axial clearance (29), said clearance being arranged axially inside the bearing (14).

7. Electrical machine according to any one of claims 1 to 6, characterized in that the armature (7) comprises a discoidal bottom (7a) on which the printed circuit (12) and the movable member (1) are stacked axially, said bottom being bordered by an axial annular rim (7b) which has an axial inner wall (13) in which an axial outer wall (15a) of the outer ring (15) is fitted.

8. Electrical machine according to claim 7, characterized in that the annular rim (7b) has a height sufficient to house the printed circuit (12) and the movable member (1) inside the frame (7).

9. Electrical machine according to one of claims 7 or 8, characterized in that the discoidal bottom (7a) has an opening (27) through which a connection (28) of the printed circuit (12) is accessible.

10. Electrical machine according to any one of claims 7 to 9, characterized in that the printed circuit (12) has a discoidal geometry complementary to that of the base (7a).

11. Electrical machine according to any one of claims 1 to 10, characterized in that the pads (8) are arranged in axial projection from a bottom (7a) of the armature (7), the printed circuit (12) has conduits (25) in which respectively a pad (8) is arranged with the coil (9) wound around said pad.

12. Electrical machine according to any one of claims 1 to 11, characterized in that the pads (8) are associated with the printed circuit (12) and / or the armature (7) ensuring their magnetic coupling with said armature.

13. An electrical machine according to any one of claims 1 to 12, characterized in that the coils (9) are each formed from several printed circuit layers (12) comprising at least one conductive turn, said turns being connected to each other to form the coils (9).

14. Electrical machine according to any one of claims 1 to 13, characterized in that it further comprises a system for determining at least one item of information relating to the movement of the mobile member (1) to manage the electrical supply system (2), said determination system comprising the encoder (3) which is capable of generating a signal representative of its movement and a sensor (4) secured to the fixed member which is capable of determining said information by reading the signal generated by said encoder.

15. Electrical machine according to claim 14, characterized in that the sensor (4) comprises at least two sensitive elements arranged at a reading distance from the magnetic track (5) of the encoder (3), said elements each being capable of emitting a signal which is a function of the field delivered by said track, the determination system comprising: - a device for processing the signals emitted by the sensitive elements which is arranged to provide two quadrature signals of the same amplitude which are each representative of the magnetic field; and - from said quadrature signals, a device for calculating information relating to the movement of the moving member (1).

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