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 moving part mounted for rotation relative to a fixed part and an electrical power supply system.

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

[0003] In one particular application, the machine is supplied with electricity to drive the moving part, for example, to motorize an actuator in a motor vehicle. In another application, the machine operates as a generator and produces electricity by moving the moving part in order 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 of ferromagnetic material which is equipped with a printed circuit forming at least one conductive coil per phase, the moving member being fixed in movement to at least two magnetic poles North and South.

[0005] In this type of electrical machine, it may be desirable to know in real time and with optimal reliability at least one piece of information relating to the movement of the moving part, 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 drive machine and / or control the electricity supplied by a generator machine.

[0006] To do this, electrical machines equipped with a determination system comprising an encoder attached to the moving part which is capable of generating a signal representative of its displacement, and a sensor attached to the fixed part 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 of 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 power supply and determination of at least one piece of information relating to the displacement of the moving part are carried out jointly, in particular in order to avoid indexing the moving part with the encoder enabling said determination.

[0009] To do this, this document proposes an electrical machine in which: - the encoder presents 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 coils are electrically connected to the power supply system by being magnetically coupled to the encoder track; - the frame includes studs around which a coil is respectively arranged.

[0010] In particular, each pad has a free surface facing the magnetic track to direct the magnetic flux between the coil and the encoder so that the power supply to the coils induces the movement of the encoder and / or the movement of the encoder induces the power supply to said coils. In particular, the free surface may have teeth of width Ld separated by grooves of width Le, the widths Ld and / or Le being such that their ratio to N.LP is neither even nor inversely even.

[0011] According to known embodiments, the moving 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 superimposed axially along said axis.

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

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

[0014] The invention aims to improve the prior art by proposing in particular an electrical machine in which the moving part is mounted in rotation while limiting the risks of tipping, while limiting the axial dimension required to implant said mounting in rotation.

[0015] To this end, the invention proposes an N-phase electrical machine comprising a moving element mounted for rotation relative to a fixed element and an electrical power supply system, said moving element 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 element comprising an armature 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 pads of ferromagnetic material around which respectively a coil is arranged, said pads having a free surface disposed opposite the magnetic track in order to direct the magnetic flux between the coil and the encoder so that the power supply to the coils induces the movement of the encoder and / or the movement of the encoder induces the power supply to said coils, the moving member - respectively the armature - having an outer peripheral ring - respectively inner -, said rings 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 fixed for rotation to the outer ring and an outer ring fixed for rotation to the inner ring, said rings being mounted for relative rotation to guide the rotation of the moving part with respect to the fixed part.

[0016] Other features and advantages of the invention will become apparent from the following description, made with reference to the accompanying figures, in which:

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

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

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

[0020] [Fig.4a] and

[0021] [Fig.4b] are schematic assembled and axial sectional representations of the electric machine of the [Fig.1], respectively in perspective ([Fig.4a]) and in front view ([Fig.4b]);

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

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

[0024] According to one application, the machine is powered by electricity to drive the moving part 1, for example, to motorize an actuator in a motor vehicle. In particular, the electric machine can be a permanent magnet synchronous motor. In another application, the machine operates as a generator and produces electricity by moving the moving part 1.

[0025] The electrical machine includes a power supply system 2 which is managed to: - in the case of a drive machine, the ability to control the movement of the moving part 1, particularly in relation to the torque and speed of movement; and / or - in the case of a generating machine, control its electrical supply, particularly in relation to the frequency of the generated electrical voltage.

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

[0027] The determination system comprises: - an encoder 3 fitted to the moving part 1, so as to be fixed to the moving part of said moving part, said encoder being capable of generating a signal representative of its movement; and - a sensor 4 attached to the fixed part 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 allowing, in particular, the determination of absolute position information. In particular, the dual-track nature of the encoder 3 makes it possible to generate a reference signal for each pole pair of a motor, thus facilitating its control.

[0030] By way of example, the encoder 3 is formed of a magnet on which the magnetic poles 6 are constituted, in particular by forming at least one magnetic track 5. In particular, the magnet may include a matrix, for example made from a plastic or elastomer material, in which magnetic particles are dispersed, in particular ferrite or rare earth particles 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 being greater than 6.

[0032] The sensitive elements of the sensor 4 are capable of each emitting a signal which is a function of the field delivered by the track 5, the determination system comprising: - a signal processing device 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 displacement of the moving organ.

[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 include at least one sensitive element, in particular selected from magnetosensitive probes, for example Hall effect, and / or probes based on tunnel magnetoresistances (TMR), anisotropic magnetoresistances (AMR) or giant magnetoresistances (GMR).

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

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

[0037] The machine includes pads 8 made of ferromagnetic material which are salient in the interface with the encoder 3, each having a head 8a whose free surface is disposed 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 on the order of 1 mm at most for a ferrite-based magnet and can go up to 10 mm for a rare earth-based magnet.

[0038] The moving member 1 can be formed by stamping a sheet of metallic material, and comprises a disc la whose periphery has an axial fold 1b which has an outer peripheral surface on which an outer peripheral ring le is formed.

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

[0040] In the description, the terms for positioning in space are taken with reference to an axis of relative rotation of the moving part 1 with respect to the fixed part (vertical in Figures 1, 3, 4a and 4b). Thus: - the terms "axial", "radial" refer to directions respectively along 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, by offsetting the rotational guidance of the moving member 1 to the outer periphery of said member, allows said guidance to be achieved over an increased diameter. Thus, the guidance can be achieved with a single bearing 14 while ensuring good stability of the rotation of the moving member 1, in particular by reducing the risk of tipping relative to the fixed member.

[0042] In the embodiment shown, the bearing 14 includes 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 has an axial outer wall 18 which is fitted onto an axial inner wall 16a of the inner ring 16.

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

[0045] The moving 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 disk 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; - bore 19 is formed in the center of said inner plate; and - the fold 1b is formed at the periphery of said outer plate.

[0047] In particular, this embodiment allows the encoder 3 to be positioned as close axially as possible to the pads 8, while benefiting from a fold 1b of sufficient axial dimension to ensure the reliability of the assembly of the bearing 14.

[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 by 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 functions of power supply and determination of at least one piece of information relating to the movement of the moving part 1. In addition, when the encoder 3 has a secondary magnetic track, the latter 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 moving part 1 and / or to control its electrical supply by the coils 9.

[0051] One coil 9 and one terminal 8 may be provided per electrical phase. According to another embodiment, several coil 9 - terminal 8 assemblies may be provided per electrical phase.

[0052] According to the embodiment shown, the encoder 3 has an annular magnetic track 5 which is fixed to a rotating movable member 1. In particular, the phase coils 9 can be alternately arranged angularly 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 - pin 8 assembly per phase, the phases consisting of one or more coils 9 being arranged at approximately 120° to each other.

[0054] According to one embodiment, the electrical machine can be operated with standard power supply system 2 management, 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 studs 8 may have teeth 10 of width Ld spaced by hollows 11 of width Le, the widths Ld and / or The 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 / 2, *4, ...) in order to direct the magnetic flux between coil 9 and encoder 3 so that the power supply to coils 9 induces the movement of encoder 3 and / or that the movement of encoder 3 induces the power supply to said coils.

[0062] In particular, the teeth 10 channel the magnetic flux successively in relation to the poles 6 of the same polarity, which creates a relative displacement force between the armature 7 and the encoder 3 attached to the moving member 1, said force inducing the displacement of said moving member in a motor 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 electric 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. Moreover, the ratio of the width Ld of the teeth 10 and / or the width Le of the hollows 11 to N.LP can be, within a manufacturing tolerance of + / - 40%, unitary or fractional.

[0065] To improve magnetic coupling, the depth of the recesses 11 must be as large 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 on the order of magnitude of the width Ld of the teeth 10.

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

[0067] Thus, the coils 9 have a reduced thickness, which is advantageous for the compactness of the machine, particularly compared to a conventional winding with copper wire in a machine of equivalent power. Furthermore, this results in greater winding robustness and a simplified design compared to the need for a special copper wire winding machine.

[0068] In particular, the printed circuit 12 may include 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 control system for the moving part 1 and / or the power supply control system, are integrated on the printed circuit board 12 of the machine's stator, which greatly reduces space and eliminates the need for connections to an external control system.

[0070] In relation to the figures, the pads 8 are arranged in axial projection from the bottom 7a of the armature 7, in particular by being formed in one 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 by ensuring their magnetic coupling with said armature.

[0071] Advantageously, the axial stacking of the printed circuit board 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 board 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 radially read equivalent. Advantageously, the encoder 3 is made of elastomeric or plasto-ferrite, which allows for great flexibility in quickly selecting the number of pole pairs 6 according to the application.

[0073] In relation to figures 1, 3, 4a and 4b, the printed circuit 12 and the moving 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 moving member inside said frame.

[0074] In addition, 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 board 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 connector 28 of the printed circuit board 12 is accessible.

[0076] Advantageously, the sensor 4 and the coils 9 are mounted on the upper surface of the printed circuit board 12, so as to define the relative position between the sensing 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, notably to facilitate the design of the printed circuit board 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 have in addition 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

1. Demands An N-phase electric machine comprising a moving member (1) mounted for rotation relative to a fixed member and an electrical power supply system (2), said moving member being equipped with an encoder (3) having a magnetic track (5) formed of a succession of npp pairs of North and South magnetic poles (6) of width (Lp) which are arranged to deliver a pseudo-sinusoidal magnetic field, the fixed member comprising an armature (7) of ferromagnetic material which is equipped with a printed circuit (12) forming at least one conducting 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) 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 power supply to the coils (9) induces the movement of the encoder (3) and / or that the movement of the encoder (3) induces the power supply to said coils, the moving member (1) - respectively the armature (7) - having an outer peripheral ring (le) - respectively inner (7c) -, said rings 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) rotationally fixed to the outer ring (le) and an outer ring (15) rotationally fixed to the inner ring (7c), said rings being mounted in relative rotation to guide the rotation of the moving member (1) with respect to the fixed member,said machine being characterized in that the moving member (1) comprises a disc (la) whose periphery has a radial fold (1b), the outer ring (le) being formed on the outer periphery of said fold, the disc (la) having 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 inner face (21) of said inner plate and the fold (1b) being formed on the periphery of said outer plate.

2. Electric 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. Electric machine according to any one of claims 1 or 2, 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.

4. Electric machine according to any one of claims 1 to 3, 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).

5. An electrical machine according to any one of claims 1 to 4, characterized in that the armature (7) comprises a discoidal base (7a) on which the printed circuit board (12) and the moving member (1) are stacked axially, said base being bordered by an axial annular rim (7b) which has an axial inner wall (13) into which an axial outer wall (15a) of the outer ring (15) is fitted.

6. Electric machine according to claim 5, characterized in that the annular rim (7b) has a sufficient height to house the printed circuit (12) and the moving member (1) inside the armature (7).

7. Electric machine according to any one of claims 5 or 6, characterized in that the discoidal base (7a) has an opening (27) through which a connector (28) of the printed circuit board (12) is accessible.

8. Electrical machine according to any one of claims 5 to 7, characterized in that the printed circuit board (12) has a discoidal geometry complementary to that of the base (7a).

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

10. An electrical machine according to any one of claims 1 to 9, characterized in that the pads (8) are associated with the printed circuit board (12) and / or the armature (7) by ensuring their magnetic coupling with said armature.

11. An electrical machine according to any one of claims 1 to 10, characterized in that the coils (9) are each formed of several layers of printed circuit board (12) comprising at least one conductive turn, said turns being connected together to form the coils (9).

12. An electrical machine according to any one of claims 1 to 11, characterized in that it further comprises a system for determining at least one piece of information relating to the displacement of the moving member (1) for managing the electrical supply system (2), said determination system comprising the encoder (3) which is capable of generating a signal representative of its displacement and a sensor (4) attached to the fixed member which is capable of determining said information by reading the signal generated by said encoder.

13. An electrical machine according to claim 12, 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 being capable of each emitting a signal which is a function of the field delivered by said track, the determination system comprising: - a signal processing device 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 the information relating to the displacement of the moving member (1).

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