N-phase electric machine

Abstract

The invention relates to a machine comprising a moving member 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 forming coils (9) that are electrically connected to a power supply system and are 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 bases (8b) being associated in ducts of the printed circuit, the printed circuit being associated with the armature (7) by the pads (8) being magnetically coupled to the armature (7).

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 bases being associated in conduits of the printed circuit, said printed circuit being associated with the armature by ensuring the magnetic coupling between the pads and the armature.

[0017] Other features and advantages of the invention will appear in the following description, given with reference to the attached figures, in which: - figure 1 is a partial schematic representation showing in perspective an electrical machine according to an 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] In relation to these figures, an N-phase electrical machine is described comprising a moving member 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.

[0020] According to one 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 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 moving member.

[0021] The electric machine includes a power supply system which is managed to:

[0022] - in the case of a driving machine, to be able to control the movement of the moving part, in particular in relation to the torque and the speed of movement; and / or

[0023] - in the case of a generator machine, check its power supply, particularly in relation to the frequency of the electrical voltage generated.

[0024] According to one embodiment, the electrical machine comprises a system for determining at least one item of information relating to the movement of the moving member, in particular arranged to deliver information relating to the position of said moving member, said information being used by the power supply system for its management. The information determined may also relate to the speed, acceleration and / or direction of movement of the moving member.

[0025] The determination system includes:

[0026] - an encoder 3 equipping the moving member, so as to be integral in movement with said moving member, said encoder being capable of generating a signal representative of its movement; and

[0027] - a sensor attached 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 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 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 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.

[0030] For example, the encoder 3 is formed from 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 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 L p of each of the magnetic poles 6 of the encoder 3 is between 0.5 and 20 mm, the number n pp of pairs of magnetic poles 6 of the encoder 3 which may be at least equal to 2, in particular being greater than 6.

[0032] The sensitive elements of the sensor are each capable of emitting a signal which is a function of the field delivered by track 5, the determination system comprising:

[0033] - 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;

[0034] - from said quadrature signals, a device for calculating information relating to the movement of the moving member.

[0035] According to one embodiment, document WO-2006 / 064169 describes a sensor 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.

[0036] In particular, the sensor may comprise at least one sensitive element, notably chosen from magnetosensitive probes, for example Hall effect, and / or probes based on tunnel magnetoresistances (TMR), anisotropic magnetoresistances (AMR) or giant magnetoresistances (GMR).

[0037] Furthermore, the calculation device may include interpolation means making it possible to increase the resolution of the information relating to the movement of the encoder 3.

[0038] The fixed member has a frame 7 made of ferromagnetic material. In the description, the terms of positioning in space are taken with reference to an axis of relative rotation of the movable member with respect to the fixed member (vertical in FIG. 1). Thus, the terms “axial” and “radial” refer to directions respectively following this axis and moving away from or approaching it. The machine comprises pads 8 made of ferromagnetic material which are projecting in 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.

[0039] 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 by being magnetically coupled to the track 5 of the encoder 3.

[0040] 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 supply and determination of at least one item of information relating to the movement of the moving member. In addition, when the encoder 3 has a secondary magnetic track, this also participates in the operation of the machine.

[0041] In particular, the power supply system is capable of using the information delivered by the determination system to control the movement of the moving member and / or to control its electrical supply by the coils 9.

[0042] 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.

[0043] According to the embodiments shown, the encoder 3 has an annular magnetic track 5 which is integral with a rotating movable member. 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.

[0044] 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.

[0045] According to one embodiment, it is possible to provide for operation of the electrical machine with standard management of the power supply system, 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:

[0046] 90 Nn pp and 270 Nn pp for N=2; and

[0047] 2707N.n pp and 4507N.n pp for N>2.

[0048] 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:

[0049] 1357N.n pp and 2257N.npp for N=2; and

[0050] 3157N.n pp and 4057N.n pp for N>2.

[0051] 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%.

[0052] 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:

[0053] 0.5 L p / N.2n pp and 1.5 L p / N.2n pp for N=2; and

[0054] L p / Nn pp and 3L p / Nn ppfor N>2. 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:

[0055] 0.75.Lp / 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

[0056] 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.

[0057] In relation to the figures, the pads 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.

[0058] According to an advantageous embodiment, the coils 9 are each formed from several layers of printed circuit 12 comprising at least one conductive turn 13, said turns being connected to each other to form the coils 9.

[0059] 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.

[0060] 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.

[0061] Advantageously, the determination system as well as the system for controlling the moving part and / or 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.

[0062] In relation to the figures, the pads 8 are formed from separate parts of the armature 7 and are each attached to said armature, the bases 8b being associated in 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.

[0063] This arrangement makes it easier to manufacture the frame 7 and the pads 8, and therefore reduces costs, but also reduces 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.

[0064] 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 axially reads the information delivered by said encoder.

[0065] 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.

[0066] Advantageously, the sensor 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 and the coils 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. In relation to FIGS. 1a and 1b, the bases 8b each have a foot 18 which projects under the conduit 16, said foot being in contact with the armature 7. In relation to FIG. 1b, the foot 18 is arranged in an orifice 20 formed in a groove of the armature 7.

[0067] 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.

Claims

CLAIMS 1. N-phase electrical machine comprising a moving member mounted to move relative to a fixed member and an electrical power supply system, said moving member being equipped with an encoder (3) having a magnetic track (5) formed of 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 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 that the movement of the encoder (3) induces the electrical supply of said coils, said machine being characterized in that the bases (8b) are associated in conduits (16) of the circuit printed (12),said printed circuit being associated with the armature (7) ensuring magnetic coupling between the pads (8) and the armature (7)., 2. Electrical machine according to claim 1, characterized in that the studs (8) are in the form of an insert having the same geometry from its free surface to its base (8b) passing through its head (8a).

3. Electrical machine according to one of claims 1 or 2, characterized in that the bases (8b) each have a foot (18) which projects under the conduit (16), said foot being in contact with the armature (7).

4. Electrical machine according to claim 3, characterized in that the foot (18) is arranged in an orifice (20) formed in a groove of the frame (7).

5. Electrical machine according to any one of claims 1 to 4, characterized in that the printed circuit (12) has metallized tubes (19) in which a conduit (16) is formed.

6. Electrical machine according to claim 5, characterized in that a conductive base layer (19a) is arranged in the continuity of the tube (19) to be at the interface between the printed circuit (12) and the armature (7).

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

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

9. Electrical machine according to claim 8, characterized in that the printed circuit (12) comprises an alternating stack of layers comprising at least one turn (13) of electrically conductive material and insulating layers (15).

10. Electrical machine according to any one of claims 1 to 9, characterized in that it further comprises a system for determining at least one item of information relating to the movement of the moving member to manage the electrical supply system, said determination system comprising the encoder (3) 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.

11. Electrical machine according to claim 10, characterized in that the sensor 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 emit 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.

12. Electrical machine according to one of claims 10 or 11, characterized in that the sensor is implanted on the surface of a printed circuit (12).

13. Electrical machine according to any one of claims 10 to 12, characterized in that the power supply system is capable of using the information delivered by the determination system to control the movement of the moving member and / or to control its electrical supply by the coils (9).

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