N-phase electric machine

Abstract

The invention relates to a machine comprising a moving member (1) provided with an encoder (3) having a track formed of north poles having a width Lp, a fixed ferromagnetic armature (7) provided with a circuit (12) forming coils (9) that are electrically connected to a power supply system (2) and magnetically coupled to the track, and ferromagnetic pads (8) with a base (8b) surrounded by a coil (9) and a head (8a) so that the supply of power to the coils (9) causes the encoder (3) to move and / or the movement thereof causes the power to be supplied, the pads (8) being mounted on the armature (7) by their base (8b) being arranged in a duct (16) of the circuit (12) and the pads being associated with the circuit and / or with the armature (7) by being magnetically coupled to the armature.

Description

[0001] N-phase electric machine

[0002] The invention relates to an N-phase electrical machine comprising a movable member mounted to move relative to a fixed member and an electrical power supply system.

[0003] 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.

[0004] In a particular application, the machine is powered with electricity to operate the movement drive of the moving 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 moving member in order to be able to power the system.

[0005] 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.

[0006] 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 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 driving machine and / or control the electricity supplied by a generating machine.

[0007] 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.

[0008] 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.

[0009] Document FR-3 114 454 proposes an electrical machine in which the functions of electrical 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 the moving member with the encoder allowing said determination.

[0010] To do this, this document proposes an electric machine in which:

[0011] - the encoder has a magnetic track formed from a succession of n pp pairs of North and South magnetic poles of width L p which are arranged to deliver a pseudo-sinusoidal magnetic field;

[0012] - the coils are electrically connected to the power supply system by being magnetically coupled to the encoder track;

[0013] - the armature comprises pads around which a coil is respectively arranged.

[0014] 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 apart by hollows of width L e , the widths Ld and / or L e being such that their relationship to NL P is not even or inversely even. The operation of this machine is satisfactory but it requires the manufacture of an armature incorporating studs, which can be complex, and the winding of the coils around said studs is restrictive for its radial dimension.

[0015] The invention aims to improve the prior art by proposing an electrical machine in which the constraints of manufacturing the pads on the armature and of radial size of the coils wound around said pads can be lifted, while guaranteeing the reliability of the magnetic coupling of the coils with the encoder.

[0016] To this end, the invention proposes an N-phase electrical machine comprising a mobile member mounted to move relative to a fixed member and an electrical power supply system, said mobile member being equipped with an encoder having a magnetic track formed from a succession of n pp pairs of North and South magnetic poles of width L pwhich are arranged to deliver a pseudo-sinusoidal magnetic field, the fixed member having 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 machine comprising pads made of ferromagnetic material each having a base around which respectively a coil is arranged and a head whose free surface is 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 pads being attached to the armature by arranging the base of said pads in respectively a conduit formed in the printed circuit,said pads being associated with said printed circuit and / or with the armature by ensuring their magnetic coupling with said armature. Other features and advantages of the invention will appear in the description which follows, made with reference to the attached figures, in which:,

[0017] - figure 1 is a partial schematic representation showing in perspective an electric machine according to one embodiment of the invention;

[0018] - figures 1a and 1b are schematic representations in axial section of the mounting of a coil around a pad, respectively according to one embodiment of the invention;

[0019] - figure 2 represents the arrangement of the encoder relative to the teeth of a pad in an electrical machine according to the invention;

[0020] - figure 3 is a schematic representation in assembled perspective and in axial section of an electrical machine according to an embodiment of the invention, figure 3a being an enlargement of figure 3 centered on the mounting of a stud on the armature;

[0021] - Figure 4 is a schematic representation in exploded perspective of the assembly of the pads on the frame of Figures 3 and 3a.

[0022] 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.

[0023] According to one application, the machine is supplied with electricity to operate the movement drive of the movable member 1, for example for the purpose of motorizing a motor vehicle actuator. In particular, the electric 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.

[0024] The electric machine comprises an electrical power supply system 2 which is managed to: - in the case of a motor machine, be able to control the movement of the moving member 1, in particular in relation to the torque and the speed of movement; and / or

[0025] - 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.

[0027] 2 for its management. The information determined may also relate to the speed, acceleration and / or direction of movement of the moving part 1.

[0028] The determination system includes:

[0029] - an encoder 3 equipping the mobile member 1, so as to be integral in movement with said mobile member, said encoder being capable of generating a signal representative of its movement; and

[0030] - a sensor 4 secured to the fixed member which is capable of determining the information by reading the signal generated by said encoder.

[0031] According to an embodiment allowing optimal resolution of the determined information, the encoder 3 has a magnetic track 5 formed from a succession of n pp pairs of 6 North and South magnetic poles of width L p 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.

[0032] According to an embodiment, known in particular from document EP-1 403 622, the encoder

[0033] 3 may have a secondary magnetic track making it possible in particular to determine absolute position information. In particular, the dual-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. For example, the encoder 3 is formed of a magnet on which the magnetic poles 6 are formed, in particular by forming at least one magnetic 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 ferrite or rare earth particles such as NdFeB, which are magnetized according to the succession of poles 6.

[0034] Advantageously with respect to the resolution of the information delivered, the width L p of each of the magnetic poles 6 of the encoder 3 is between 0.5 and 20 mm, the number n ppof pairs of magnetic poles 6 of the encoder 3 which may be at least equal to 2, in particular being greater than 6.

[0035] 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:

[0036] - 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;

[0037] - from said quadrature signals, a device for calculating information relating to the movement of the moving member.

[0038] 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.

[0039] 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). 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.

[0040] The fixed member has a frame 7 made of ferromagnetic material. In Figures 3, 3a and 4, the frame 7 comprises a plate 7b in the center of which a shaft 7a extends axially, the movable member 1 comprising:

[0041] - an axis 1a mounted in rotation in said barrel by means of two rolling bearings 14 stacked axially in said barrel; and

[0042] - an upper bell 1 b comprising an annular radial collar on the lower surface of which the encoder 3 is associated.

[0043] 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 figures 1, 3, 3a and 4). Thus, the terms “axial”, “radial” refer to directions respectively following this axis and moving away from or approaching it.

[0044] The machine comprises studs 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 studs 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.

[0045] The armature 7 is equipped with a printed circuit 12 forming at least one conductive coil 9 per phase, each pad 8 having a base 8b around which respectively a coil 9 is arranged, said coils being electrically connected to the power supply system 2 by being magnetically coupled to the track 5 of the encoder 3. 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 electrical power supply and determination of at least one item of information relating to the movement of the moving member 1. In addition, when the encoder 3 has a secondary magnetic track, this also participates in the operation of the machine.

[0046] 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.

[0047] 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.

[0048] According to the embodiments 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.

[0049] 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.

[0050] 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 is angularly spaced from the geometric center of a coil 9 of another phase by an integer multiple of an angle between:

[0051] 90 Nn pp and 270 Nn pp for N=2; and

[0052] 2707N.n pp and 4507N.n pp for N>2. 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:

[0053] 135 Nn pp and 225 Nn pp for N=2; and

[0054] 3157N.n pp and 4057N.n pp for N>2.

[0055] 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.n pp for N= 2 and 3607N.n pp for N> 2, with an angle tolerance of + / - 50%.

[0056] According to another embodiment, the encoder 3 has a linear magnetic track 5 which is integral with a mobile member 1 mounted in translation, the coil 9 of one phase having a geometric center which is linearly spaced from the geometric center of a coil 9 of another phase by an integer multiple of a distance between:

[0057] 0.5 L p / N.2n pp and 1.5 L p / N.2n pp for N=2; and

[0058] L p / Nn pp and 3L p / Nn pp for N>2.

[0059] In particular, the geometric center of a coil 9 of one phase is linearly spaced from the geometric center of a coil 9 of another phase by an integer multiple of a distance between:

[0060] 0.75 L p / N.2n pp and 1.25 L p / N.2n pp , in particular being of the order of L p / N.2n pp for N=2; and

[0061] 1.5L p / Nn pp and 2.5L p / Nn pp , in particular being of the order of 2L p / Nn pp for N>2.

[0062] In relation to figures 1, the studs 8 are in the form of a ferromagnetic insert, for example made of steel, having the same geometry, for example cylindrical, from its free surface to its base 8b via its head 8a. In relation to figures 2 to 4, the free surface of each of the studs 8 may have teeth 10 of width Ld spaced apart by hollows 11 of width Le . Advantageously, the widths Ld and / or L e may be such that their relationship to NL P is not even nor inversely even (i.e. the ratio L e / NL PP or Ld / NL PP is not equal to 2, 4 ... or to Vz, %, ...) 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.

[0063] 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.

[0064] Thus, thanks to the presence of these sets of teeth 10 - hollows 11, 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 L p sufficiently reduced for the resolution of the determined displacement information, and this without requiring mechanical indexing since the magnetic operation of the machine is provided by the encoder 3 which allows the determination of said information.

[0065] Advantageously, the width Ld of the teeth 10 is analogous to the width L e hollows 11. Furthermore, the ratio of the width Ld of the teeth 10 and / or the width L e troughs 11 to NL P may be, within a manufacturing tolerance of + / - 40%, unitary or fractional.

[0066] 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 may be of the order of magnitude of the width Ld of the teeth 10. According to an advantageous embodiment, the coils 9 are each formed from several printed circuit layers 12 comprising at least one conductive turn 13, 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, a 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 relation to figures 1a and 1b, the printed circuit 12 comprises an alternating stack of layers comprising at least one turn 13 made of electrically conductive material, for example copper, and insulating layers 15.

[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 pads 8 are formed from separate parts of the armature 7, and are each attached to said armature by arranging their base in a conduit 16 formed in the printed circuit 12, said pads being associated with said printed circuit and / or with the armature 7 by ensuring their magnetic coupling with said armature.

[0071] This arrangement makes it easier to manufacture the frame 7 and the pads 8, and therefore to reduce their costs, but also to reduce the weight of the pads 8, also allowing a significant weight saving, in particular of the order of 17%, for the machine as a whole. In relation to figures 2 to 4, each of the bases 8b in the conduits 16 is surrounded by a coil 9 whose internal turns 13a are at least partially inscribed under the free surface 8c of the head 8a of the corresponding pad 8.

[0072] This arrangement makes it possible, by offsetting the free surface of the pads 8 above the printed circuit 12, to benefit from a space under the head 8a to significantly limit, in particular by around 15%, the radial size necessary for winding the coils and / or increase the number of turns 13 and / or reduce the length of the turns 13 and therefore their resistance to significantly improve the performance of the machine.

[0073] 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.

[0074] In particular, a 3 encoder with an axial 5 magnetic track is simpler to manufacture than its radial reading equivalent. Advantageously, the 3 encoder is made of elasto or plasto-ferrite, which allows great flexibility to quickly choose the number of pole pairs 6 depending on the application.

[0075] Furthermore, figures 3 and 3a represent the mounting of the barrel 7a through a central opening 17 of the printed circuit 12, in order to allow axial superposition of said printed circuit on the plate 7b of said frame.

[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] In relation to figures 1a and 1b, the bases 8b are associated in the conduits 16 of the printed circuit 12, said printed circuit being associated with the armature 7, for example by riveting, ensuring the magnetic coupling between the pads 8 and the armature 7.

[0078] To do this, the bases 8b each have a foot 18 which projects under the conduit 16, said foot being in contact with the frame 7. In relation to figure 1b, the foot 18 is arranged in an orifice 20 formed in a groove of the frame 7.

[0079] Furthermore, the printed circuit 12 has metallized tubes 19 in which a conduit 16 is formed. It is thus possible to ensure good thermal coupling, in particular by providing a conductive base layer 19a in the continuity of the tube 19 to be at the interface between the printed circuit 12 and the armature 7 (figure 1 b) in order to serve as a heat sink and ground plane. Thus, the thermal management of the machine can also be ensured by the pads 8.

[0080] In particular, the plate 7b has orifices 20 formed in the axial extension of the conduits 16 of the printed circuit 12, the bases 8b being associated in said orifices by being magnetically coupled with the armature 7. In relation to figures 3, 3a and 4, the printed circuit 12 can be held axially between the plate 7b of the armature 7 and the free surface 8c of the heads 8a.

[0081] As shown in particular in Figure 4, 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, in particular teeth 10 of width Ld spaced apart by hollows 11 of width L e as described above. Advantageously, the heads 8a have a maximum dimension along the magnetic track 5 which is large, in order to optimize the magnetic interference zone between the pads 8 and said magnetic track.

[0082] Conversely, the bases 8b have a maximum dimension along the track 5 which is reduced to a minimum, in order to limit their size in the circuit 12 and to have sufficient space in said circuit for the coils 9. In particular, the maximum dimension of the bases 8b along the track is at least five times smaller than the corresponding maximum dimension of the head 8a.

[0083] Similarly:

[0084] - the heads 8a have a maximum radial dimension sufficiently large to optimize the magnetic interference zone with track 5;

[0085] - the bases 8b have a limited maximum radial dimension to have more radial space in the circuit 12 to install the coils 9.

[0086] To do this, the bases 8b may have a maximum radial dimension which is at least twice smaller than the maximum radial dimension of the heads 8a.

Claims

CLAIMS 1. N-phase electrical machine comprising a moving member (1) mounted to move relative to a fixed member and an electrical supply system (2), said moving member being equipped with an encoder (3) having a magnetic track (5) formed from a succession of n pp pairs of magnetic poles (6) North and South of width (L p) which are arranged to deliver a pseudo-sinusoidal magnetic field, the fixed member having 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 machine comprising pads (8) made of ferromagnetic material each having a base (8b) around which respectively a coil (9) is arranged and a head (8a) whose free surface is 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 the movement of the encoder (3) induces the electrical supply of said coils,said machine being characterized in that the pads (8) are attached to the armature (7) by arranging the base (8b) of said pads in a conduit (16) formed in the printed circuit (12), said pads being associated with said printed circuit and / or with the armature (7) by ensuring their magnetic coupling with said armature., 2. Electrical machine according to claim 1, characterized in that the free surface of the heads (8a) having teeth (10) of width (Ld) spaced by hollows (11) of width (L e ), the widths (Ld) and / or (L e ) being such that their relation to NL P is not even nor inversely even.

3. Electrical machine according to one of claims 1 or 2, characterized in that each of the bases (8b) in the conduits (16) is surrounded by a coil (9) whose internal turns (13a) are at least partially inscribed under the free surface (8c) of the head (8a) of the corresponding stud (8).

4. Electrical machine according to any one of claims 1 to 3, characterized in that the bases (8b) are associated in the conduits (16) of the printed circuit (12), said printed circuit being associated with the armature (7) ensuring the magnetic coupling between the pads (8) and the armature (7).

5. Electrical machine according to any one of claims 1 to 3, characterized in that the armature (7) has orifices (20) in the extension of the conduits (16) of the printed circuit (12), the bases (8b) being associated in said orifices by being magnetically and / or thermally coupled with the armature (7).

6. Electrical machine according to any one of claims 1 to 5, characterized in that the encoder (3) is arranged axially above the printed circuit (12) to form an axial magnetic flux machine.

7. Electrical machine according to any one of claims 1 to 6, characterized in that the coils (9) are each formed from several printed circuit layers (12) comprising at least one conductive turn (13), said turns being connected to each other to form the coils (9).

8. Electrical machine according to any one of claims 1 to 7, characterized in that 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 having a plurality of teeth (10) extending radially.

9. Electrical machine according to claim 8, characterized in that the bases (8b) have a maximum dimension along the magnetic track (5) which is at least five times smaller than the corresponding maximum dimension of the head (8a).

10. Electrical machine according to any one of claims 2 to 9, characterized in that the bases (8b) have a radial dimension maximum which is at least twice less than the maximum radial dimension of the heads (8a).

11. Electrical machine according to any one of claims 1 to 10, characterized in that it further comprises a system for determining at least one item of information relating to the movement of the movable 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.

12. Electrical machine according to claim 11, 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).

13. Electrical machine according to one of claims 11 or 12, characterized in that the sensor (4) is implanted on the surface of a printed circuit (12).

14. Electrical machine according to any one of claims 11 to 13, characterized in that the power supply system (2) is capable of using the information delivered by the determination system to control the movement of the moving member (1) and / or to control its electrical supply by the coils (9).

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