Aircraft propulsion system comprising a device for acquiring the rotational speed of the rotor of the electric motor

Abstract

Propulsion system of an aircraft comprising a device for acquiring the rotational speed of the rotor of the electric motor Propulsion system (10) of an aircraft comprising an electric motor (12) comprising a wound stator (16) and a rotor (14) configured to generate a magnetic field and to be driven in rotation, so that said magnetic field is rotating;and a device (40) for acquiring the rotational speed of the rotor comprising at least one electrical measuring circuit (42) having a turn (48) comprising an electrically conductive material and extending between the first and second terminals of the electrical measuring circuit, said turn being mounted on the stator and surrounding a mounting portion of said stator, such that when said rotor is rotated, said turn is crossed by a magnetic flux coming from the rotor which varies over time, inducing a voltage at the terminals of the electrical measuring circuit, the acquisition device being configured to determine the rotational speed of said rotor from said voltage at the terminals of the electrical measuring circuit. Figure for the abstract: Fig. 2.;

Description

Title of the invention: Aircraft propulsion system comprising a device for acquiring the rotation speed of the rotor of the electric motor Technical field

[0001] The present invention relates to the technical field of propulsion systems for propelling aircraft. The invention relates more specifically to electric or hybrid propulsion systems comprising an electric motor. Traditionally, such an electric motor comprises a wound stator and a rotor configured to be driven in rotation when a magnetic field is generated at the stator. In these propulsion systems, the rotational speed of the rotor must be determined in a redundant and supervised manner in order to guarantee the proper operation of the electric motor.

[0002] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are being or will be adopted by various states. In particular, an ambitious standard applies both to new types of aircraft and those in circulation requiring the implementation of technological solutions in order to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0003] Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental consequences with the aim of improving the energy efficiency of aircraft.

[0004] Consequently, the Applicant is constantly working to reduce its negative climate impact by using methods and operating virtuous development and manufacturing processes and minimizing greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0005] This sustained research and development work covers both new generations of aircraft engines, the lightening of aircraft, in particular through the materials used and the lightened on-board equipment, the development of the use of electrical technologies to provide propulsion, and, as essential complements to technological progress, aeronautical biofuels Prior art

[0006] Propulsion systems are known that include sensors for the angular position of the rotor of the electric motor. However, these angular position sensors have the disadvantage of being particularly heavy and bulky, which makes their integration into known electric motors particularly difficult. These angular position sensors are also fragile and risk being damaged. They are also very expensive.

[0007] One solution to avoid the integration of such large and bulky sensors is to place Hall effect probes within the stator windings of the electric motor. However, these probes cannot operate in a liquid medium. Such probes therefore cannot be used to determine the rotational speed of the rotor of electric motors whose stator slots are immersed in a coolant, for example oil or glycol. These probes also cannot operate at high temperatures, generally above 150°C, which further limits the possible applications. Their integration is particularly complex near the stator winding which tends to heat up.

[0008] Solutions are also known that do not use any sensors, called "sensorless" measurement solutions. In these systems, it is planned to measure the voltage at the terminals of the electric motor. A disadvantage is that at low rotation speeds of the rotor of the electric motor, the voltage at the terminals of the latter is also particularly low. Consequently, the rotor rotation speed data determined at low speeds are then not very accurate. Statement of the invention

[0009] An aim of the present invention is to propose an aircraft propulsion system which overcomes the aforementioned drawbacks.

[0010] To do this, the invention relates to a propulsion system for an aircraft, the system comprising: - at least one electric motor for propelling the aircraft, the electric motor comprising a wound stator and a rotor configured to generate a magnetic field and to be driven in rotation, so that said magnetic field is rotating; and - a device for acquiring the rotational speed of the rotor comprising at least one electrical measuring circuit having a first terminal, a second terminal and a turn comprising an electrically conductive material extending between said first and second terminals, said turn being mounted on the stator and surrounding a mounting portion of said stator, so that when said rotor is rotated, said coil is crossed by a magnetic flux coming from the rotor which varies over time, inducing a voltage at the terminals of the electrical measuring circuit, the acquisition device being configured to determine the speed of rotation of said rotor from said voltage at the terminals of the electrical measuring circuit.

[0011] The invention is the result of technological research aimed at very significantly improving the performance of aircraft and, in this sense, contributes to reducing the environmental impact of aircraft.

[0012] In a non-limiting manner, the electric motor may be a synchronous or asynchronous motor. In a non-limiting manner, the electric motor may be a permanent magnet synchronous motor, a wound rotor asynchronous motor or an induction asynchronous motor.

[0013] In a known manner, the rotor is configured to generate a magnetic field. In a non-limiting manner, the magnetic field generated by the rotor may be the result of a plurality of magnetic fields actually generated by said rotor. The rotor advantageously comprises at least one permanent magnet making it possible to generate said magnetic field. Alternatively, and without departing from the scope of the invention, the rotor may comprise an electromagnet comprising a winding making it possible to generate said magnetic field.

[0014] Preferably, the stator extends along a longitudinal axis. The rotor extends inside the stator. The rotor advantageously extends along the longitudinal axis of the stator and is rotatable relative to the stator, around the longitudinal axis.

[0015] Alternatively, and without departing from the scope of the invention, the electric motor may be a so-called axial motor, so that the stator and the rotor are arranged axially next to each other.

[0016] Still in a known manner, the rotor is configured to be driven in rotation when a magnetic field is generated by the stator, by the interaction of the magnetic field generated by the rotor with the magnetic field generated by the stator. The rotation of the rotor sets the magnetic field generated by the latter in rotation. In other words, the magnetic field of the rotor is rotating given the rotation of the rotor. The magnetic field is said to be rotating considered relative to the stator.

[0017] The turn of the electrical measuring circuit being mounted on the stator, the latter is crossed by the lines of the magnetic field generated by the rotor. As a result, said magnetic flux crosses said turn. In other words, the turn embraces the magnetic flux. This magnetic flux is expressed according to the relationship:

[0018] ¢ = BS = BS.cosa

[0019] where ¢ is the magnetic flux through the coil, B is the vector of the magnetic field generated by the rotor and £ is the vector of the surface of the coil crossed by the magnetic field, and a is the angle between the vector B and the vector S-

[0020] Given the rotation of the rotor, and therefore the magnetic field that it generates which is also driven in rotation, this magnetic flux through the turn varies over time between a positive maximum magnetic flux value and a minimum magnetic flux value of the same amplitude but negative. This is due to the variation in the angle of incidence between the magnetic field and the turn and therefore between the vector and the vector 5. This magnetic flux advantageously varies in a sinusoidal manner.

[0021] By electromagnetic induction, this variation of the magnetic flux through the turn of the electrical measuring circuit induces a voltage U between the first and second terminals of said electrical measuring circuit. According to the Lenz-Faraday law, this voltage across the terminals of the electrical measuring circuit is equal to the induced electromotive force and verifies the equation:

[0022] u— dt

[0023] where N is the number of turns of the electrical measuring circuit.

[0024] Preferably, said voltage across the terminals of the electrical measuring circuit is sinusoidal. This voltage corresponds to the electromotive force induced by the rotor.

[0025] Preferably, the acquisition device further comprises a processing unit electrically connected to said electrical measuring circuit and configured to determine the rotation speed of the rotor from said voltage across the terminals of the electrical measuring circuit.

[0026] The rotational speed of said rotor is advantageously determined from the frequency of said voltage across the terminals of the electrical measuring circuit. This frequency is for example obtained by determining the time interval between two instants when said voltage is zero, or by determining the number of cancellations of said voltage over a predetermined time interval.

[0027] Alternatively and without departing from the scope of the invention, the determination of the rotation speed can be determined directly from the amplitude of the voltage at the terminals of the electrical circuit, which is proportional to said rotation speed.

[0028] Preferably, said voltage across the terminals of the electrical measuring circuit makes it possible to determine a so-called electrical rotation speed. The mechanical rotation speed of the rotor is then advantageously determined by dividing the so-called electrical rotation speed by the number of pairs of magnets which make up the rotor.

[0029] According to the invention, said turn for measuring a voltage induced by the rotor, in order to determine a rotation speed of the latter, has a reduced size, weight and cost compared to the solutions of the prior art, and in particular compared to known angular position sensors. In addition, such a turn is not very fragile, and is not very sensitive to high temperatures. This turn of the electrical measurement circuit can therefore be integrated into the electric motor, and arranged near the stator coils. It can also be immersed in a liquid, in particular a coolant, without this impacting its measurement performance or the accuracy of the rotation speed finally determined. This measurement solution using a turn is also reliable, regardless of the rotor rotation speed, and in particular at low rotor rotation speeds. Consequently, the acquisition device according to the invention is therefore particularly versatile and can be integrated into numerous propulsion systems, to measure the rotor rotation speed of a wide variety of electric motors.

[0030] Preferably, the coil comprises copper. Preferably, the coil comprises at least one copper core. Preferably, the coil comprises a wire made of conductive material, for example a copper wire, wound on itself so as to form the coil.

[0031] Preferably, said turn defines a non-closed loop. Alternatively, and without departing from the scope of the invention, said turn may form a closed loop. In which case an induced electric current flows in said turn, together with the appearance of the voltage at the terminals of the electrical circuit.

[0032] Advantageously, the turn extends in a plane parallel to the longitudinal axis of the stator. Preferably, said turn extends in a longitudinal direction. Preferably, the turn has an oblong shape. Preferably, the turn comprises a first longitudinal conduction portion and a second longitudinal conduction portion extending substantially parallel to the first longitudinal conduction portion. Said longitudinal conduction portions are advantageously spaced apart from each other. One advantage is to increase the surface area of ​​the turn crossed by the magnetic field generated by the rotor and therefore the intensity of the magnetic flux. Preferably, the turn comprises at least one end portion in an arc of a circle connecting said first and second longitudinal conduction portions.

[0033] In a non-limiting manner, the mounting portion of said stator may be a portion of a tooth or of the yoke of the stator. Said mounting portion is a portion crossed by the magnetic field lines of the rotor. Said mounting portion is chosen so that the turn which surrounds it has a satisfactory span to encompass a significant part of the magnetic flux resulting from the magnetic field generated by the rotor.

[0034] In a non-limiting manner, the coil may partially or completely surround said mounting portion of the stator. Preferably, the coil completely surrounds said mounting portion of the stator.

[0035] Preferably, said mounting portion has a substantially rectangular shape. This shape facilitates the winding of the coil around said mounting portion, in particular when said coil is oblong in shape.

[0036] In a non-limiting manner, the acquisition device may comprise several electrical measurement circuits, each making it possible to acquire the rotation speed of the rotor. The redundancy of the acquisition device is thus improved.

[0037] Advantageously, said electrical measuring circuit comprises a winding comprising a plurality of turns comprising a conductive material and arranged in cascades relative to each other and surrounding said mounting portion of the stator. One advantage is to increase the voltage induced at the terminals of the electrical measuring circuit. This makes it possible to improve the accuracy of the voltage measurement and therefore of the rotor rotation speed subsequently determined. Indeed, according to the equation given previously, said voltage at the terminals of the electrical measuring circuit is proportional to the number of turns connected in cascade in the electrical measuring circuit and crossed by the magnetic field.

[0038] Advantageously, the stator comprises a peripheral yoke and a plurality of teeth distributed around the circumference of the yoke and extending radially towards the inside of said yoke, said turn of the electrical measuring circuit being mounted on one of said teeth or on the yoke. The mounting portion of the stator is therefore a portion of a tooth or of the yoke of the stator. In other words, in this embodiment, the turn of the electrical measuring circuit surrounds at least a portion of a tooth or of the yoke of the stator.

[0039] It has been found that the magnetic field lines generated by the rotor are guided along the height of the teeth, from the distal end to the foot of said teeth. The magnetic field lines are also guided along the periphery of the yoke. Therefore, positioning the turn around a portion of the yoke or a tooth of the stator makes it possible to embrace a significant magnetic flux coming from the rotor. This therefore makes it possible to obtain a voltage at the terminals of the electrical measuring circuit that is all the more significant. The accuracy of the rotation voltage of the rotor determined from this voltage is therefore further improved.

[0040] The yoke advantageously has a cylindrical shape. The yoke advantageously extends along the longitudinal axis of the stator. Said teeth of the stator advantageously extend radially considered relative to the longitudinal axis of the stator.

[0041] According to an advantageous variant, said turn of the electrical measuring circuit surrounds said tooth of the stator to which it is mounted. In this variant, the turn extends around the periphery of the tooth. The turn is then crossed by the magnetic field generated by the rotor which is guided according to the height of the tooth. The amplitude of the voltage measured at the terminals of the electrical measuring circuit is all the greater. The magnetic field lines within the tooth are then substantially transverse to said turn.

[0042] The tooth advantageously comprises a first lateral flank and a second flank lateral, said turn surrounding said lateral flanks of the tooth. In this variant, the turn extends in a plane transverse to the tooth, considered according to the height of the latter. The turn extends in a plane substantially perpendicular to a plane passing through said tooth and through the longitudinal axis of the stator. The turn flanks the lateral flanks of the tooth.

[0043] Preferably, the stator comprises at least one coil surrounding said tooth and allowing the generation of a magnetic field for driving the rotor in rotation, said turn being arranged between said tooth and said coil. The turn of the electrical measuring circuit advantageously describes a winding around the tooth substantially similar to the winding of said coil.

[0044] Advantageously, said tooth is covered with a layer of electrically insulating material, the turn being arranged between said tooth and said layer of electrically insulating material.

[0045] According to a preferred embodiment, said tooth surrounded by the turn of the electrical measuring circuit comprises a foot connected to said yoke, said turn surrounding the foot of the tooth. Said foot forms a base of the tooth. The foot forms a proximal portion of the tooth. The mounting portion of the stator here corresponds to said foot of the tooth. According to this configuration, the turn is arranged at the junction between the tooth and the yoke. This makes it possible to maintain said turn more effectively around said tooth and to prevent it from becoming detached. The turn extends close to the yoke.

[0046] The turn of the electrical measuring circuit is advantageously positioned between the stator coil surrounding said tooth and the yoke, which further improves its retention.

[0047] According to another preferred embodiment, said tooth surrounded by the turn of the electrical measuring circuit comprises a distal end portion, said turn surrounding said distal end portion of the tooth. In this configuration, the distal end portion of the tooth constitutes the mounting portion of the stator. This configuration facilitates the mounting and dismounting of the turn of the electrical measuring circuit, by making said turn particularly accessible. This configuration makes it possible to position the turn between the end of the tooth and a stator coil surrounding said tooth. In other words, said stator coil extends between the turn and the yoke. It is not necessary to dismount the stator coil in order to be able to mount or dismount said turn of the electrical measuring circuit.

[0048] Said distal end portion is advantageously opposite the foot of the tooth. This distal end portion is also called the isthmus of the tooth.

[0049] Advantageously, the stator extends along a longitudinal axis and said tooth surrounded by the turn of the electrical measuring circuit has at least one lateral flank in which a longitudinal slot is formed, said turn extending at least by entially in said longitudinal slot. In this embodiment, the turn extends partly inside the tooth. One advantage is to effectively maintain said turn in position in order to prevent it from slipping towards the distal end or towards the foot of the tooth. The mounting of the turn to the tooth is therefore improved. Another advantage is to move the turn away from the stator coil surrounding the tooth, thus reducing the risk of short circuit. In addition, since said stator coil is a significant source of heat, the turn of the electrical measuring circuit is therefore subjected to lower temperatures, which reduces the risk of damage to the latter.

[0050] In a non-limiting manner, said longitudinal slot may be formed in the root or in the distal end portion of the tooth. Said slot has a width slightly greater than the thickness of the turn. The longitudinal slot extends substantially parallel to the longitudinal axis of the stator. The longitudinal slot extends along the lateral flank of the tooth.

[0051] Preferably, said tooth surrounded by the turn further comprises a first lateral flank in which a first longitudinal slot is formed and a second lateral flank, opposite the first lateral flank, and in which a second longitudinal slot is formed, said turn extending at least partially into said first and second longitudinal slots.

[0052] According to another advantageous variant, the stator extends along a longitudinal axis, and said tooth to which the turn of the electrical measuring circuit is mounted comprises a distal end portion defining an internal face of the tooth arranged opposite the rotor, at least one longitudinal groove being formed in said internal face of the tooth, said turn of the electrical measuring circuit extending at least partially in said longitudinal groove. The turn then extends partly in the distal end portion of the tooth. One advantage is to move the turn away from the stator coil surrounding the tooth, which is a source of heat, further reducing the risk of the turn heating as well as the risks of short circuit.

[0053] Preferably, a first longitudinal groove and a second longitudinal groove, distant from the first longitudinal groove, are formed in said internal face of the tooth, said turn of the electrical measuring circuit extending at least partially in said first longitudinal groove and in said second longitudinal groove. In this configuration, the turn surrounds an end portion of the tooth extending between the first and second longitudinal grooves. This end portion of the tooth extending between the first and second longitudinal grooves then constitutes the mounting portion of the stator to which the turn is mounted.

[0054] The first and second longitudinal grooves are advantageously parallel.

[0055] According to another advantageous variant, the stator comprises a plurality of notches separating each of the consecutive teeth of the stator, so that the stator comprises a alternating teeth and notches, said turn of the electrical measuring circuit surrounding the yoke so that it extends partly inside a notch. It is understood that the turn comprises a first conduction portion extending in the notch, along an inner face of the yoke, and a second conduction portion extending outside the yoke, along an outer face of the yoke. The mounting portion of the stator to which the turn is mounted then corresponds to the yoke.

[0056] The turn of the electrical measuring circuit then advantageously extends in a plane passing through the longitudinal axis of the stator. This configuration allows the turn to embrace a significant magnetic flux, insofar as the lines of the magnetic field generated by the rotor propagate around the circumference of the yoke and pass largely through said turn. In other words, the vector of the magnetic field is then essentially transverse to the plane in which the turn extends. One advantage is to distance the turn from the stator coils surrounding the teeth of the stator, in order to reduce the risks of short circuit and heating of said turn. In addition, the amplitude of the acquired voltage is high, which guarantees the accuracy of the rotation speed of the rotor determined from this voltage.

[0057] According to an advantageous embodiment, said turn of the electrical measuring circuit is located near one of the two teeth defining the notch in which it extends. In this configuration, the turn comprises a first conduction portion arranged in the notch near said tooth. The turn is advantageously arranged in the corner formed between one of the teeth and the yoke.

[0058] According to another advantageous embodiment, said turn extends in a median plane situated substantially equidistant from the two teeth defining the notch in which it extends. The tooth then extends at a distance from the two teeth defining the notch. An advantage is to move the turn even further away from the electrical measuring circuit relative to the coils surrounding the teeth.

[0059] Said median plane advantageously passes through the longitudinal axis of the stator.

[0060] Preferably, the mounting portion of the stator is covered with a layer of electrically insulating material, said turn being arranged at least partially between said layer of insulating material and said mounting portion. One advantage is to reduce the risks of short circuit between the turn of the electrical measuring circuit and the stator coils surrounding the teeth of the stator. Preferably, the turn is arranged between said layer of insulating material and the tooth or between said layer of insulating material and the yoke.

[0061] Preferably, the layer of insulating material is a notch insulator disposed in the notch and covering the tooth and the yoke.

[0062] Advantageously, the coil comprises a core made of conductive material, for example example in copper, and a sheath of electrically insulating material surrounding said core. Another advantage is to reduce the risks of short circuit between the turn of the electrical measuring circuit and the stator coils surrounding the teeth of the stator

[0063] The invention also relates to an aircraft comprising at least one propulsion system as described above. Brief description of the drawings

[0064] The invention will be better understood on reading the following description of embodiments of the invention given as non-limiting examples, with reference to the appended drawings, in which:

[0065] [Fig.l] [Fig.l] is a sectional view of a first embodiment of a propulsion system according to the invention;

[0066] [Fig.2] [Fig.2] is a zoomed-in view of the stator of the propulsion system of [Fig.l];

[0067] [Fig.3] [Fig.3] is a sectional view, from above, of the propulsion system of [Fig.2];

[0068] [Fig.4] [Fig.4] illustrates the propagation of the magnetic field lines of the rotor within the stator of the electric motor;

[0069] [Fig.5] [Fig.5] illustrates a second embodiment of a propulsion system according to the invention;

[0070] [Fig.6] [Fig.6] illustrates a third embodiment of a propulsion system according to the invention;

[0071] [Fig.7] [Fig.7] illustrates a fourth embodiment of a propulsion system according to the invention;

[0072] [Fig.8] [Fig.8] illustrates a fifth embodiment of a propulsion system according to the invention;

[0073] [Fig.9] [Fig.9] illustrates a sixth embodiment of a propulsion system according to the invention; and

[0074] [Fig.l0] [Fig. 10] illustrates a seventh embodiment of a propulsion system according to the invention. Description of the embodiments

[0075] The invention relates to a propulsion system for an aircraft, the system comprising in particular an electric motor and a device for acquiring the rotational speed of the rotor of the electric motor.

[0076] [Fig.l] is a sectional view of a propulsion system 10 of an aircraft, according to the invention. The propulsion system 10 comprises an electric motor 12 comprising a rotor 14 and a stator 16. The stator 16 is fixed relative to the aircraft, while the rotor 14 is configured to be driven in rotation relative to the stator, around a longitudinal axis X. The stator extends along said longitudinal axis X. In this non-limiting example, the rotor 14 comprises a plurality of permanent magnets 18 configured to generate a magnetic field. The rotation of the rotor 14 causes the rotation of the magnetic field that it generates, which is therefore rotary or rotating. It is also noted that, in a known manner, the stator 16 comprises a yoke 20, of generally cylindrical shape, extending around said longitudinal axis X.

[0077] Still in known manner, the stator 16 further comprises a plurality of teeth 22 distributed over the periphery of the yoke. These teeth 22 extend radially from the yoke 20, inwards, in the direction of the longitudinal axis X. These teeth 22 have a generally parallelepiped shape.

[0078] All the teeth 22 of the stator 16 are substantially identical, so that only one of them will be described here. [Fig. 2] is a view of the propulsion system of [Fig. 1] zoomed in on one of these teeth 22. It can be seen that the tooth 22 comprises a foot 24 connected to the yoke 20 and forming the base of the tooth. The tooth further comprises a distal end portion 26, opposite the foot 24. The distal end portion 26 further defines an internal face 28 of the tooth, arranged opposite the rotor 14 and configured to come into contact with a hoop. The tooth further has a first lateral flank 23 and a second lateral flank 25 opposite the first lateral flank 23.

[0079] The tooth 22 is surrounded by a stator coil 30 comprising a plurality of turns distributed over the height of the tooth. This coil 30 surrounds the first and second lateral flanks 23, 25 of the tooth. All of the coils 30 surrounding the teeth 22 of the stator constitute the winding of the stator 16 configured to generate a magnetic field. The interaction between the magnetic field generated by the rotor and the magnetic field generated by the stator 16 makes it possible to drive the rotor 14 in rotation.

[0080] The cylinder head further comprises an outer face 19 and an inner face 21.

[0081] The successive teeth define notches 32, so that the stator comprises an alternation of notches 32 and teeth 22. The coils 30 extend partly inside these notches. Within the notches 32, the lateral flanks 23, 25 of the teeth 22, as well as the inner face 21 of the yoke are covered with a layer of electrically insulating material 34 constituting a notch insulator. This layer of insulating material 34 extends between the coil 30 and the tooth 22.

[0082] According to the invention, the propulsion system 10 further comprises a device 40 for acquiring the rotational speed of the rotor 14. This acquisition device 40 comprises an electrical measuring circuit 42 illustrated in the sectional view, from above, of [Fig. 3]. In this figure, it can be seen that the electrical measuring circuit 42 has a first terminal 44, a second terminal 46. The electrical measuring circuit 42 further comprises a turn 48, called the measuring turn, extending between said first and second terminals 44, 46. In a non-limiting manner, the turn 48 is formed by a copper wire covered with a sheath of electrically insulating material and wound on itself.

[0083] According to the invention, said turn 48 surrounds a mounting portion of the stator 16. More precisely, in the first embodiment of FIGS. 2 and 3, the turn surrounds the root 24 of the tooth 22. The root 24 of the tooth 22 forms a mounting portion of the turn to the stator. The turn 48 has an oblong shape, so that it comprises a first longitudinal conduction portion 50 extending along the first lateral flank 23 of the tooth 22, and a second longitudinal conduction portion 52 extending along the second lateral flank 25 of the tooth. The first and second conduction portions 50, 52 are connected by an arcuate portion.

[0084] In the non-limiting example of Figures 2 and 3, the turn 48 extends in a plane transverse to the tooth, considered according to the height of the latter. This plane corresponds to the section plane of [Fig.3]. The turn 48 extends in a plane perpendicular to a plane passing through the longitudinal axis of the stator and through the tooth 22. The turn extends in a plane parallel to the longitudinal axis X.

[0085] The acquisition device 40 further comprises a processing unit, not shown, electrically connected to the terminals 44, 46 of the electrical measurement circuit 42. This processing unit is configured to determine a rotation speed of the rotor from a voltage measured at the terminals 44, 46 of the electrical measurement circuit 42.

[0086] When the rotor 14 is rotated, the magnetic field that it generates is also rotated with the rotor, so that the magnetic flux passing through the turn 48 varies over time, between a maximum magnetic flux value, positive, and a minimum magnetic flux value, of the same amplitude, but negative.

[0087] In this non-limiting example, the rotor 14 comprises an alternation of magnets 18 which are successively pivoted 180° relative to each other, so that the vectors of the magnetic field which they generate are also pivoted 180°. These magnets define an alternation of south poles and north poles.

[0088] When a first permanent magnet 18, for example a north pole, generating a magnetic field whose vector is directed towards the turn 48 is positioned opposite the tooth 22, said turn 48 then embraces a significant part of the magnetic flux resulting from this magnetic field. In particular, as illustrated in [Fig.4], the lines L of the magnetic field generated by this first permanent magnet 18 of the rotor are guided over the entire height of the tooth 22, from the distal end portion 26 to the foot 24 of the tooth, then inside the yoke 20. From then on, the turn defines a surface transverse to these lines L of magnetic field which pass through it. The magnetic flux through the turn 48 and associated with this first magnet is then maximum.

[0089] The maximum value of the magnetic flux is all the more important as the turn embraces a large part of this magnetic flux, taking into account its positioning around the tooth 22. When the rotor pivots further, a second magnet 18, directly consecutive to the first magnet and pivoted by an angle of 180° relative to the first magnet, is brought opposite the tooth 22. This second magnet 18 forms a south pole. Taking into account the orientation of this second magnet, the vector of the magnetic field is oriented in a direction opposite to the turn 48. The magnetic flux generated by this magnet through the turn then has a minimum and negative value.

[0090] When the turn 48 is located opposite the space formed between two consecutive magnets, the magnetic flux through the turn 48 is substantially zero.

[0091] The magnetic flux through the coil 48 therefore varies sinusoidally as the rotor rotates.

[0092] This variation in the magnetic flux induces a voltage at the terminals 44, 46 of the electrical measuring circuit 42, which corresponds to the induced electromotive force. This induced voltage is sinusoidal.

[0093] From this induced voltage, the processing unit of the acquisition device 40 is configured to determine, by calculation, the rotation speed of the rotor 14. Here, in a non-limiting manner, the rotation speed of the rotor is determined by identifying the frequency of said voltage at the terminals 44, 46 of the electrical measurement circuit 42. This frequency is for example determined by identifying the times when the voltage at the terminals of the electrical measurement circuit is zero.

[0094] Since the turn 48 is crossed by a significant magnetic flux, given its positioning around the tooth 22, the voltage induced at the terminals 44, 46 of the electrical measuring circuit 42 has a high amplitude. Therefore, the determined rotation speed of the rotor is all the more precise.

[0095] [Fig. 5] illustrates a second embodiment of the propulsion system 10 according to the invention. In this second embodiment, the turn 48 of the electrical measuring circuit 42 of the acquisition device 40 is mounted on the tooth 22 so that it surrounds the distal end portion 26 of the tooth 22. The distal end portion 26 of the tooth 22 forms a mounting portion of the turn 48 on the stator 16. The turn 48 is arranged between the coil 30 surrounding the tooth 22 and the end of the tooth. This configuration also allows the turn 48 to embrace a significant part of the flux, ensuring that a high amplitude voltage is obtained at the terminals 44, 46 of the electrical measuring circuit 42. This makes it possible to precisely determine the rotational speed of the rotor. Another advantage is that the coil 48 can be dismantled, respectively mounted, without it being necessary to dismantle, respectively mount, the coil 30 at the tooth 22 beforehand.

[0096] [Fig. 6] illustrates a third embodiment of the propulsion system 10 according to the invention. In this third embodiment, a first longitudinal slot 54 is formed in the first lateral flank 23 of the tooth 22. In addition, a second longitudinal slot 56, parallel to the first longitudinal slot 54, is formed in the second lateral flank 25. The first and second longitudinal slots 54, 56 extend substantially parallel to the longitudinal axis X of the stator. These longitudinal slots are formed in a central portion 27 of the tooth 22, located between the distal end portion 26 and the root 24 of the tooth.

[0097] The turn 48 extends partly inside said first and second longitudinal slots 54, 56. More precisely, the first longitudinal conduction portion 50 extends in the first longitudinal slot 54, while the second longitudinal conduction portion 52 extends in the second longitudinal slot 56. In this configuration, the turn 48 is kept at a distance from the coil 30 surrounding the tooth, which reduces the risk of short circuit. In addition, the arrangement of the turn 48 in the longitudinal slots 54, 56 prevents it from sliding along the tooth 22 and becoming detached. The mounting of the turn around the tooth is improved.

[0098] [Fig.7] illustrates a fourth embodiment of the propulsion system 10 according to the invention. In this fourth embodiment, a first longitudinal groove 60 and a second longitudinal groove 62 are formed in the internal face 28 of the tooth, defined by the distal end portion 26 of the tooth. The first and second longitudinal grooves 60, 62 are parallel to each other and spaced apart from each other. They are also parallel to the longitudinal axis X of the stator.

[0099] The turn 48 extends partly inside said first and second longitudinal grooves 60, 62. More precisely, the first longitudinal conduction portion 50 extends in the first longitudinal groove 60, while the second longitudinal conduction portion 52 extends in the second longitudinal groove 62. The turn 48 then extends partly in the distal end portion 26 of the tooth. The turn surrounds a portion of the tooth extending between the two longitudinal grooves 60, 62, and which forms a mounting portion. This configuration makes it possible to move the turn 48 even further away from the coil 30 surrounding the tooth 22. The risks of short-circuiting and heating of the electrical measuring circuit 42 are further reduced.

[0100] [Fig. 8] illustrates a fifth embodiment of the propulsion system 10 according to the invention. In this fifth embodiment, the turn 48 surrounds the yoke 20 of the stator 16, so that it extends partly into the notch 32. This configuration allows the turn to embrace a significant part of the magnetic flux coming from the rotor, the lines of the magnetic field of the rotor being guided on the circumference of the yoke, as illustrated in [Fig. 4], and therefore through the turn. The turn extends transversely to the yoke 20, in a plane passing through the axis Ion- longitudinal X of the stator 16. The turn has a first longitudinal conduction portion 50 extending in the notch 32, along the inner face 21 of the yoke. The turn further has a second longitudinal conduction portion 52 extending along the outer face 19 of the yoke.

[0101] In this non-limiting embodiment, the turn 48 is arranged near the tooth 22, so that the first longitudinal conduction portion 50 is arranged near the root 24 of the tooth, in the corner formed between the yoke and the tooth. The first longitudinal conduction portion 50 of the turn is arranged between the coil 30, the yoke and the tooth.

[0102] [Fig. 9] illustrates a sixth embodiment of the propulsion system 10 according to the invention. In this sixth embodiment, the turn 48 also surrounds the yoke 20 of the stator 16, so that it extends partly into the notch 32. Compared to the fifth embodiment of [Fig. 8], the turn 48 here surrounds a central portion of the yoke 20 located substantially halfway between the two teeth 22 defining the notch 32. The turn 48 then extends in a median plane located substantially equidistant from the two teeth 22 defining the notch in which it extends. An advantage here again is to distance the turn 48 from the coils 30 surrounding the teeth 22.

[0103] [Fig. 10] illustrates a seventh embodiment in which the electrical measuring circuit 42 comprises a plurality of turns 48, forming a winding. One advantage is to increase the value of the voltage induced at the terminals 44, 46 of the electrical measuring circuit. In a non-limiting manner, the turns, and therefore the winding, here surround the distal end portion 26 of the tooth 22.

Claims

Claims

1. Propulsion system (10) of an aircraft, the system comprising: - at least one electric motor (12) for propelling the aircraft, the electric motor comprising a wound stator (16) and a rotor (14) configured to generate a magnetic field and to be driven in rotation, so that said magnetic field is rotating;and - a device (40) for acquiring the rotational speed of the rotor comprising at least one electrical measuring circuit (42) having a first terminal (44), a second terminal (46) and a turn (48) comprising an electrically conductive material extending between said first and second terminals, said turn being mounted on the stator and surrounding a mounting portion of said stator, so that when said rotor is rotated, said turn is crossed by a magnetic flux coming from the rotor which varies over time, inducing a voltage at the terminals of the electrical measuring circuit, the acquisition device being configured to determine the rotational speed of said rotor from said voltage at the terminals of the electrical measuring circuit.;

2. A propulsion system according to claim 1, wherein said electrical measuring circuit (42) comprises a winding comprising a plurality of turns (48) comprising a conductive material and arranged in cascades relative to each other and surrounding said stator mounting portion (16).

3. A propulsion system according to claim 1 or 2, wherein the stator (16) comprises a peripheral yoke (20) and a plurality of teeth (22) distributed around the circumference of the yoke and extending radially towards the inside of said yoke, said turn (48) of the electrical measuring circuit (42) being mounted on one of said teeth or on the yoke.

4. Propulsion system according to claim 3, wherein said turn (48) of the electrical measuring circuit (42) surrounds said tooth (22) of the stator (16) to which it is mounted.

5. Propulsion system according to claim 4, wherein said tooth (22) surrounded by the turn (48) of the electrical measuring circuit (42) comprises a foot (24) connected to said yoke (20), said turn surrounding the foot of the tooth.

6. A propulsion system according to claim 4, wherein said tooth (22) surrounded by the turn (48) of the electrical measuring circuit (42) comprises a distal end portion (26), said turn surrounding said distal end portion of the tooth.

7. Propulsion system according to any one of claims 4 to 6, in which the stator (16) extends along a longitudinal axis (X) and in which said tooth (22) surrounded by the turn (48) of the electrical measuring circuit (42) has at least one lateral flank (23, 25) in which a longitudinal slot (54, 56) is formed, said turn extending at least partially in said longitudinal slot.

8. Propulsion system according to claim 3, wherein the stator (16) extends along a longitudinal axis (X), and wherein said tooth (22) to which the turn (48) of the electrical measuring circuit (42) is mounted comprises a distal end portion (26) defining an internal face (28) of the tooth arranged opposite the rotor (14), at least one longitudinal groove (60, 62) being formed in said internal face of the tooth, said turn of the electrical measuring circuit extending at least partially in said longitudinal groove.

9. A propulsion system according to claim 8, wherein said inner face (28) of the tooth comprises a first longitudinal groove (60) and a second longitudinal groove (62) parallel to the first longitudinal groove, said turn (48) of the electrical measuring circuit (42) extending at least partially inside said first and second longitudinal grooves.

10. A propulsion system according to claim 3, wherein the stator (16) comprises a plurality of notches (32) separating each of the consecutive teeth (22) of the stator, such that the stator comprises an alternation of teeth and notches, said turn (48) of the electrical measuring circuit (42) surrounding the yoke (20) such that it extends partly inside a notch.

11. Propulsion system according to claim 10, wherein said turn (48) of the electrical measuring circuit (42) is located near one of the two teeth (22) defining the notch (32) in which it extends.

12. Propulsion system according to claim 10, wherein said coil (48) extends in a median plane situated substantially equidistant from the two teeth (22) defining the notch (32) in which it extends.

13. A propulsion system according to any one of claims 3 to 12, wherein the stator mounting portion (16) is covered with a layer of electrically insulating material (34), said turn (48) being disposed at least partially between said layer of insulating material and said mounting portion.

14. A propulsion system according to any one of claims 1 to 13, wherein said coil (48) comprises a core of conductive material, for example copper, and a sheath of electrically insulating material surrounding said core.

15. Aircraft comprising at least one propulsion system (10) according to any one of claims 1 to 14.

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