Turbomachine comprising a module for correcting a torsion mode of a transmission line connected to an electric machine and associated method

Abstract

An aircraft turbomachine (T) comprising an electric machine (1) connected to a transmission line (2) and a control device (3) configured to determine the currents flowing in the electric machine (1) so that it provides an electric machine torque in accordance with a control torque, the control device (3) comprising a correction module configured to attenuate a torsional mode excitation (Mt) of the transmission line (2), the correction module being configured to attenuate the torsional mode excitation (Mt) of the transmission line (2), the control device (3) being configured to calculate the control torque from the setpoint torque (TRQcons) and a correction torque calculated from a rotational speed (Nhp) of the propulsion shaft (Ahp) over a frequency range encompassing the estimated torsional frequency. Abstract figure: Figure 2

Description

Title of the invention: Turbomachine comprising a module for correcting a torsion mode of a transmission line connected to an electric machine and associated method Technical field

[0001] The present invention relates to the field of electrical machines embedded in a turbomachine of an aircraft in order to achieve hybrid propulsion. The invention is particularly advantageous for an electrical machine connected to a propulsion shaft of an aircraft turbomachine via a transmission line, this electrical machine being configured to operate in a motor mode to rotate the propulsion shaft or in a generator mode to generate electrical energy.

[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 factors impacting 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 ensure propulsion, and, essential complements technological progress, aviation biofuels.

[0006] It is known in the prior art to mount an electrical machine on a propulsion shaft of an aircraft turbomachine, for example a fan shaft, in order to obtain a hybrid turbomachine. The electrical machine is in particular configured to operate in a generator mode in order to take mechanical power from the propulsion shaft so as to generate electrical power. The electrical machine is also configured to operate in a motor mode in order to provide mechanical power to the propulsion shaft by taking electrical power, for example, from an electric battery.

[0007] With reference to [Fig.l], in order to facilitate the integration of the electrical machine 1, it has been proposed to connect it to a propulsion shaft of the Ahp turbomachine by a transmission line 2 comprising an internal transmission box 21 known by its English designation “IGB” for “Internal Gear Box”, a radial transmission shaft 22 known by its English designation “RDS” for “Radial Drive Shaft” and an accessory relay box 23, known by its English designation “AGB” for “Accessory Gear Box”. In a known manner, the electrical machine 1 comprises a stator 11 and a rotor 12 configured to magnetically interact with the stator 11. The aircraft turbomachine 1 comprises a control device 103 configured to receive a setpoint torque TRQcons and determine the currents flowing in the stator 11 so that the rotor 12 provides an electrical machine torque in accordance with the setpoint torque TRQcons.

[0008] In this example, the currents flowing in the stator are determined following a measurement of intensity values ​​of said currents.

[0009] In practice, during operation of the transmission line 2 in motor or generator mode, a torsion mode Mt is likely to appear in the transmission line 2. A torsion mode Mt corresponds in particular to an oscillation of torque and speed at a torsion frequency. The torsion mode Mt may manifest itself for example in the form of a torsion of the radial transmission shaft 22, that is to say, an angular offset between two longitudinal portions of the radial transmission shaft 22.

[0010] Such a torsion mode Mt affects the performance of the transmission line 2 and can induce excitations or resonances which lead to premature wear of the elements of the transmission line 2 but also wear of the electrical machine 1.

[0011] An immediate solution would be to increase the stiffness of the transmission line 2 to increase the mode frequency while increasing the damping of the chain to reduce the sensitivity of the torsional mode Mt. Such a solution is not feasible since this would increase the mass of the transmission line 2 as well than its size, which would partly ruin the advantages linked to hybridization.

[0012] Another known solution consists of adding a mechanical or hydraulic damper in order to attenuate the excitation of the torsion mode Mt. Such a solution has the disadvantage of increasing the on-board mass. In addition, a mechanical damper has a limited lifespan. For example, it should not be used in permanent mode.

[0013] Furthermore, these solutions do not necessarily make it possible to attenuate the torsion mode Mt independently of the type of electrical machine 1, in particular, without accessing the internal measurements of the electrical machine 1 and without resorting to a unit for observing the currents of the electrical machine 1 which is expensive and complex to implement due to the constraints of size and mass. PRESENTATION OF THE INVENTION

[0014] The invention relates to an aircraft turbomachine comprising at least one propulsion shaft and an electrical machine connected to the propulsion shaft by a transmission line configured to transmit a mechanical torque between the propulsion shaft and the electrical machine, the electrical machine being configured to receive a setpoint torque, the transmission line being subjected to a torsion mode having an estimated torsion frequency, the electrical machine comprising a stator and a rotor configured to interact magnetically with the stator, the electrical machine being configured to operate, on the one hand, in a generator mode in order to take mechanical power from the rotor to generate electrical power and to operate, on the other hand, in a motor mode in order to inject mechanical power from an electrical network and to drive the rotor.

[0015] The aircraft turbomachine is remarkable in that it comprises a control device configured to determine the currents flowing in the stator so that the rotor provides an electric machine torque in accordance with a control torque, the control device comprising a correction module configured to attenuate an excitation of the torsional mode of the transmission line, the control device being configured to calculate the control torque from the setpoint torque and a correction torque.

[0016] The correction module is configured to calculate the correction torque from a rotational speed of the propulsion shaft over a frequency range encompassing the estimated torsional frequency, designated "monitoring range".

[0017] Thus, thanks to the invention, the torsion mode of the transmission line is corrected dynamically both during a transient regime and during a permanent regime, which makes it possible to increase the service life of the electrical machine and the transmission line, by reducing the torque variations of the electrical machine. Such a correction is also advantageous when the electric machine operates in a motor mode or a generator mode. Transitions between the two modes are also facilitated. In steady state, the correction is small, which saves the electric machine and prevents its untimely use. In addition, since the damping is carried out in software, there is no addition of a mechanical part whose mass would be penalizing and which would need to be replaced.

[0018] Advantageously, it is not necessary to add new sensors to the electric machine or to access measurements of said electric machine, which facilitates integration. By using a measurement of the rotation speed of the propulsion shaft, the correction module is advantageously independent of the electric machine. It is thus possible to use any type of electric machine, which facilitates logistics and reduces costs.The rotational speed of the propulsion shaft is advantageously measured reliably and over the entire operating range of the aircraft turbomachine. In addition, the mechanical excitation can thus be measured at a location further away from the electrical machine. This makes it possible to see how the mechanical chain behaves when faced with the sampling / injection of the most powerful equipment positioned on the accessory relay box (when the latter is present).

[0019] According to one aspect, the transmission line comprises at least one radial transmission shaft and an accessory relay box. Such a transmission line is particularly efficient but subject to a torsion mode.

[0020] According to one aspect, the transmission line comprises at least one internal transmission housing. According to one aspect, the transmission line comprises at least one adapter housing.

[0021] According to one aspect, the turbomachine is hybrid and comprises a combustion chamber for generating an exhaust flow for rotating the propulsion shaft.

[0022] According to one aspect, the speed of the propulsion shaft being linked to the speed of the electric machine by a predetermined speed ratio, the correction module comprises a conversion block configured to convert the speed of the propulsion shaft into a time speed of the electric machine, designated "time measurement". This advantageously makes it possible to move from the reference frame of the propulsion shaft to the reference frame of the electric machine in order to achieve optimal damping.

[0023] According to one aspect, the correction module comprises a gain operator having a gain for multiplying the time measurement. This advantageously allows the correction speed of the torsion mode to be adjusted.

[0024] According to one aspect, the correction module comprises a high-pass filter for cutting frequencies below the monitoring range. Preferably, the high-pass filter has a cutoff frequency corresponding to a lower bound Ftel of the monitoring range, the lower bound being between Fte / 3 and Fte / 2, Fte being the estimated torsion frequency.

[0025] In one aspect, the correction module includes a low-pass filter to cut frequencies above the monitoring range and thereby eliminate all high-frequency noise to improve correction.

[0026] According to one aspect, the correction module comprises a saturator to limit the correction torque and thus protect the mechanical chain against the injection of an unwanted transient overtorque.

[0027] Preferably, the monitoring range has a width of between 10 Hz and 50 Hz. Such a reduced width makes it possible to precisely target the actual torsion frequency while allowing for an admissible variation linked to wear and the particular specificities of each transmission line.

[0028] According to one aspect, the control device is configured to determine control currents of the electrical machine from the control torque.

[0029] Also presented is a method for correcting the torsion mode of the transmission line of the aircraft turbomachine as presented previously, the electric machine receiving a setpoint torque, the method comprising steps consisting of: • Calculate a correction torque from the rotational speed of the propulsion shaft over a frequency range encompassing the estimated torsional frequency, designated the “monitoring range”, and • Calculate a control torque from the reference torque and the correction torque.

[0030] According to another aspect, the invention relates to a computer program product comprising code instructions which, when these code instructions are executed by a processing unit, cause said processing unit to implement such a torsion mode correction method. PRESENTATION OF FIGURES

[0031] The invention will be better understood on reading the description which follows, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0032] [Fig.l] is a schematic representation of an aircraft turbomachine according to the prior art.

[0033] [Fig.2] is a schematic representation of an aircraft turbomachine according to an embodiment of the invention.

[0034] [Fig.3] is a schematic representation of the control device of the electric machine comprising a correction module.

[0035] [Fig.4] is a schematic representation of the correction module.

[0036] [Fig.5] is a schematic representation of a measurement of the torsional torque at level of the adaptation box, in time (curve 5a) and in frequency (curve 5b), when the correction is inactive (A).

[0037] [Fig.6] is a schematic representation of the measurement of the torsion torque at the level of the adaptation box, in time (curve 6a) and in frequency (curve 6b), when the correction is active (B).

[0038] [Fig.7] is a schematic representation of the variations in mechanical torque at the level of a shaft of the electrical machine when the correction is inactive (A) and active (B) for a first torque setpoint.

[0039] [Fig.8] is a schematic representation of the variations in mechanical torque at a shaft of the electrical machine when the correction is inactive (A) and active (B) for a second torque setpoint.

[0040] It should be noted that the figures set out the invention in detail to implement the invention, said figures can of course be used to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0041] With reference to [Fig. 2], there is shown an aircraft turbomachine T comprising a low pressure compressor 101, a high pressure compressor 102, a high pressure turbine 103 and a low pressure turbine 104. A low pressure shaft Abp connects the low pressure compressor 101 to the low pressure turbine 104. A high pressure shaft Ahp connects the high pressure compressor 102 to the high pressure turbine 103. A fan 100 is mounted integrally with the low pressure shaft Abp. The aircraft turbomachine T comprises a combustion chamber (not shown) for consuming a mixture of fuel and a pressurized air flow accelerated by the compressors 101, 102. An exhaust flow makes it possible to rotate the turbines 103, 104. The high pressure shaft Ahp and the low pressure shaft Abp are both propulsion shafts since they are main shafts which participate in the propulsion.The architecture of such an aircraft turbomachine T is known to those skilled in the art and will not be presented in further detail.

[0042] In a known manner, with reference to [Fig. 2], the aircraft turbomachine T comprises a computer 5 configured to measure a high pressure rotation speed Nhp of the high pressure shaft Ahp and a low pressure rotation speed Nbp of the high pressure shaft Ahp. The rotation speeds Nhp, Nbp are advantageously measured reliably and over the entire operating range of the aircraft turbomachine T.

[0043] In this example, the aircraft turbomachine T is hybrid and comprises an electrical machine 1 connected to the high pressure shaft Ahp by a transmission line 2 configured to transmit a mechanical torque between the high pressure shaft Ahp and the electrical machine 1. It nevertheless goes without saying that the invention also applies to an electrical machine 1 connected to the low pressure shaft Abp by a transmission line 2 or directly connected to the low pressure shaft Abp.

[0044] In this example, with reference to [Fig.2], the transmission line 2 preferably comprises successively from the high pressure shaft Ahp to the electrical machine 1: • an internal transmission box 21, known by its English designation “IGB” for “Internal Gear Box”, • a radial drive shaft 22, known by its English designation “RDS” for “Radial Drive Shaft”, • an accessory relay box 23, known by its English designation “AGB” for “Accessory Gear Box”, and • a 24 adapter box, known by its English designation “GBX” for “GearBox”.

[0045] Preferably, the computer 5 is connected to one or more speed sensors mounted on the aircraft turbomachine T, in particular, connected to the accessory relay box 23.

[0046] The internal transmission housing 21 comprises gears and is housed as close as possible to the high pressure shaft Ahp to enable power to be transmitted / received. The radial transmission shaft 22 preferably extends in a radial arm of the turbomachine T in order to cross a stream of air accelerated by the fan 100. The radial transmission shaft 22 has a degree of flexibility and is particularly sensitive to a torsion mode Mt. The accessory relay housing 23 comprises a plurality of gears for receiving different accessories such as a starter, a lubrication device, etc.

[0047] In this example, optionally, the transmission line 2 comprises an adaptation box 24 configured to adapt the speed from the accessory relay box 23 in order to allow the electrical machine 1 to generate electrical energy with high efficiency. Preferably, the adaptation box 24 comprises a device for measuring the torque of the transmission line 2, in particular a torque meter.

[0048] It goes without saying that the transmission line 2 could have a different structure.

[0049] As previously indicated, the transmission line 2 is subjected to a torsion mode Mt having an actual torsion frequency Ftr which is not necessarily known precisely. Indeed, the actual torsion frequency Ftr varies between each aircraft turbomachine T and between each transmission line 2 due to the different settings, the different wear and the level of loading of the transmission line 2. The actual torsion frequency Ftr thus changes depending on time and conditions.

[0050] The transmission line 2 can be modeled by a damping system connecting, on the one hand, the electrical machine 1 having a high rigidity and, on the other hand, the high pressure shaft Ahp. The damping system comprises a torsional stiffness according to two degrees of freedom in the reference frame of the electrical machine 1. The torsional stiffness is advantageously defined in a plane orthogonal to the axis of the electrical machine 1.

[0051] As will be presented later, the correction is optimal in the present case given that the inertia ratio of the electric machine 1 on the high pressure shaft Ahp is low, for example, of the order of 1 / 40.

[0052] The torsion mode Mt can manifest itself for example in the form of a torsion of the radial transmission shaft 22, that is to say, an angular offset between two longitudinal portions of the radial transmission shaft 22.

[0053] As an example, with reference to [Fig. 5], a measurement of the mechanical torque received by the adaptation box 24 is shown in the absence of correction in time (curve 5a) and in frequency (curve 5b). In this example, the actual torsion frequency Ftr is of the order of 25 Hz.

[0054] As will be presented later, an estimated torsion frequency Fte is determined by calculation, in particular, from a mathematical model of the transmission line 2, for example by simulation or by feedback.

[0055] Advantageously, a frequency range encompassing the estimated torsion frequency Fte, designated “monitoring range Ps”, is determined from the estimated torsion frequency Fte. This monitoring range Ps comprises a lower bound Ftel and an upper bound Fte2. The monitoring range Ps is preferably centered on the estimated torsion frequency Fte but it could be offset relative to said estimated torsion frequency Fte.

[0056] Preferably, the monitoring range Ps has a width, i.e. a difference between its lower limit Ftel and its upper limit Fte2, of between 10 Hz and 50 Hz. Such a monitoring range Ps is sufficiently wide to encompass the possible variations of the estimated torsion frequency Fte and sufficiently narrow to avoid encompassing undesirable frequencies. Preferably, the lower limit Ftel is between Fte / 3 and Fte / 2. Preferably, the upper limit Fte2 is between 2*Fte and 3*Fte.

[0057] In this example, the estimated torsion frequency Fte was measured at 23 Hz and the monitoring range Ps is equal to [10 Hz; 50 Hz] and thus has a width of 40 Hz.

[0058] With reference to [Fig. 2], the electrical machine 1 comprises a stator 11 fixedly mounted in the turbomachine T and a rotor 12 connected to the transmission line 2, in particular, to the adapter box 24. In the absence of an adapter box 24, the rotor 12 is connected directly to the accessory relay box 23. The rotor 12 is rotatably mounted relative to the stator 11 along an electric machine axis X. The rotor 12 is configured to interact magnetically with the stator 11. The electrical machine 1 is for example of the permanent magnet synchronous machine (PMSM) type. These magnets are for example mounted at the surface of the rotor 12. The electrical machine 1 could also be of the wound rotor type.

[0059] Preferably, the electrical machine 1 is free of mechanical shock absorber because the damping by the latter is not optimal and it is difficult to integrate. In addition, such a mechanical shock absorber wears out quickly and needs to be changed periodically. It is also an additional on-board mass.

[0060] The electrical machine 1 is configured, on the one hand, to operate in a generator mode in order to take mechanical power from the rotor 12 (coming in the present example from the high pressure shaft Ahp) to generate electrical power and to operate, on the other hand, in a motor mode in order to inject electrical power to generate mechanical power and drive the rotor 12 and the high pressure shaft Ahp.

[0061] Still with reference to [Fig. 2], the aircraft turbomachine T further comprises a control device 3 configured to receive a setpoint torque TRQcons. The control device 3 of the electric machine 2 may be adjacent to the latter or remote from the latter. The setpoint torque TRQcons is preferably determined by a computer 5 of the turbomachine T or by a computer of the aircraft, for example in order to achieve the chosen hybridization rate.

[0062] An exemplary embodiment of a control device 3 is illustrated in [Fig. 3]. The control device 3 is configured to determine the currents flowing in the stator 11 so that the rotor 12 provides an electric machine torque TRQ in accordance with a control torque TRQ*. The control device 3 comprises a unit 31 for determining a setpoint reverse current Iq* from the control torque TRQ*. The control device 3 also comprises a unit 32 for determining a setpoint forward current Id*. The setpoint currents Iq*, Id* are converted into a setpoint voltage Vq*, Vd* by a conversion unit 33 after integration of the setpoint currents Iq*, Id* by PI (Proportional Integral) operators from current measurements of the currents Iq, Id flowing in the stator 11 of the electric machine 1.

[0063] In this example, currents labc are measured at the stator 11 of the electrical machine 1 and are converted in a vector manner into a direct current Id and a reverse current Iq by knowing an angular position 0 of the rotor 12 relative to the stator 11. The electrical machine 1 is controlled via a vector control dq as illustrated in [Fig.3].

[0064] The conversion unit 33 determines the setpoint voltages Vq*, Vd* by knowing the speed w of the rotor 12 relative to the stator 11 in order to carry out defluxing. Preferably, the speed w of the rotor 12 is obtained by integrating the angular position 0.

[0065] According to one aspect, the angular position 0 of the rotor 12 relative to the stator 11 is obtained by a monitoring unit 36 ​​which can be connected to an angular sensor 37 or to an observation unit (not shown) which makes it possible to determine the angular position 0 from the measurement of the control currents labc.

[0066] The setpoint voltages Vq*, Vd* from the conversion unit 33 are transformed into a control voltage Vabc* by a dq / abc converter and then processed by a control unit 34 in order to provide a control parameter (MLI signal for example) to an inverter 35 supplying the electrical machine 1, in particular, its stator 11.

[0067] The general structure of a control device 3 is known to those skilled in the art and will not be presented in more detail. In this example, the angular position 0 of the rotor 12 and the speed w of the rotor 12 are obtained from the monitoring unit 36 ​​and / or the angular sensor 37 which can just as easily carry out a direct measurement as implement an estimator.

[0068] The control device 3 comprises a correction module 4 configured to correct the torsion mode Mt (i.e. to attenuate the excitation of the torsion mode Mt) of the transmission line 2. This advantageously makes it possible to reduce the torque variations of the electric machine 1 to make the hybridization of the turbomachine T possible and to avoid breakage of the mechanical chain and to increase its service life. The control device 3 is configured to calculate the control torque TRQ* from the setpoint torque TRQcons and a correction torque TRQcorr.

[0069] According to the invention, the correction module 4 is configured to calculate the correction torque TRQcorr from the high pressure rotation speed Nhp of the high pressure propulsion shaft Ahp over a frequency range encompassing the estimated torsion frequency Fte, designated “monitoring range Ps”.

[0070] Thus, the correction torque TRQcorr is determined indirectly without requiring direct access to a speed measurement of the electrical machine 1. This makes it possible to carry out a correction of the torsion torque Mt for any type of machine. electric 1.

[0071] In this example, with reference to [Fig. 3], the control device 3 comprises a subtractor 38 configured to determine the control torque TRQ* by subtracting the correction torque TRQcorr from the setpoint torque TRQcons. The correction module 4 makes it possible to measure the variations induced by the torsion mode Mt in order to determine a correction torque TRQcorr which modifies the setpoint torque TRQcons. In other words, the correction module 4 implements active and dynamic compensation in order to control the electrical machine 1 while taking into account the torsion mode Mt to attenuate the torque / speed oscillations. The correction torque TRQcorr is injected in phase opposition with the torque and speed disturbance linked to the torsion mode Mt, which achieves a damping effect.

[0072] With reference to [Fig.4], an embodiment of a correction module 4 is shown schematically. In this example, the correction module 4 successively comprises a conversion block 40, a low-pass filter 41, a high-pass filter 42, a gain operator 43 having a gain Kp and a saturator 44.

[0073] The high pressure speed Nhp of the high pressure propulsion shaft Ahp is connected to the speed of the electric machine Mw, i.e. the speed w of the rotor 12, by a predetermined speed ratio RV which depends on the different reduction ratios of the transmission line 2. Such a predetermined speed ratio RV is known to those skilled in the art.

[0074] With reference to [Fig. 4], the correction module 4 comprises a conversion block 40 configured to convert the high pressure speed Nhp of the propulsion shaft Ahp into an electric machine speed Mw, designated “time measurement Mw”. ​​Such a conversion block 40 is simple to implement due to the knowledge of the predetermined speed ratio RV. This advantageously makes it possible to return to the reference frame of the electric machine 1 in order to achieve optimal compensation of the torsion mode Mt.

[0075] The low-pass filter 41 is applied to the time measurement Mw to achieve a frequency cutoff at the upper limit Fte2 of the monitoring range Ps. This advantageously makes it possible to remove high-frequency noise that is not related to the torsion mode Mt.

[0076] The high-pass filter 42 is applied to the time measurement Mw to achieve a frequency cutoff at the lower limit Ftel of the monitoring range Ps. This advantageously makes it possible to remove the average component of the time measurement and to keep only the wave component of the time measurement.

[0077] The gain operator 43 makes it possible to determine the desired correction level. It is preferably determined as a function of the torsional stiffness of the damping system representing the transmission line 2. The gain Kp makes it possible to calibrate the correction so that it is effective while avoiding the risk of instability.

[0078] The saturator 44 advantageously makes it possible to limit the value of the correction torque TRQcorr so as not to make the correction unstable while allowing reactive correction. It is important that the correction torque TRQcorr remains low compared to the setpoint torque TRQcons, for example, less than 10% of the setpoint torque TRQcons in transient mode of the turbomachine T and less than 1% of the setpoint torque TRQcons in steady state.

[0079] The invention has been presented for a high pressure speed measurement Nhp because the electrical machine 1 is connected to the high pressure shaft Ahp in this example. It goes without saying that the invention applies in a similar manner to a low pressure speed measurement Nbp when the electrical machine 1 is connected to the low pressure shaft Abp.

[0080] An example of implementation of a method for correcting a torsion mode of the transmission line 2 will now be presented.

[0081] The method comprises steps consisting of: • Calculate a correction torque TRQcorr from the rotation speed Nhp of the propulsion shaft Ahp over a frequency range encompassing the estimated torsion frequency Fte, designated “monitoring range Ps”. • Calculate a control torque TRQ* from the reference torque TRQcons and the correction torque TRQcorr.

[0082] With reference to [Fig.6], a measurement of the mechanical torque received by the adaptation box 24 is shown during a correction in time (curve 6a) and in frequency (curve 6b). If we compare to [Fig.5], the variations in the mechanical torque are significantly reduced. The actual torsion frequency Ftr has been compensated and is no longer visible on the frequency spectrum of curve 6b.

[0083] [Fig.7] illustrates a measurement signal SI of the variations in mechanical torque over time for a setpoint torque TRQcons of the order of -10 NM (generator mode) in the absence of correction (phase A) and in the presence of correction (phase B). It is advantageous to note that the variations are strongly attenuated in the presence of correction (phase B). The correction is also reactive, the oscillations disappearing in three periods. The effectiveness of the correction is also visible in [Fig.8] which illustrates a measurement signal S2 of the variations in mechanical torque over time for another setpoint torque TRQcons of the order of -20 Nm (generator mode) in the absence of correction (phase A) and in the presence of correction (phase B). The correction is thus robust for a large range of setpoint torques TRQcons.

[0084] Thanks to the invention, a mode of twisting of a transmission line of a tur- The hybrid machine can be effectively corrected by dynamic correction of the electric machine control, which increases the life of the mechanical chain and avoids the risk of breakage due to over-torque.

Claims

Claims

1. Aircraft turbomachine (T) comprising at least one propulsion shaft (Ahp) and an electrical machine (1) connected to the propulsion shaft (Ahp) by a transmission line (2) configured to transmit a mechanical torque between the propulsion shaft (Ahp) and the electrical machine (1), the electrical machine (1) being configured to receive a setpoint torque (TRQcons), the transmission line (2) being subjected to a torsion mode (Mt) having an estimated torsion frequency (Fte), the electrical machine (1) comprising a stator (11) and a rotor (12) configured to interact magnetically with the stator (11), the electrical machine (1) being configured to operate, on the one hand, in a generator mode in order to take mechanical power from the rotor (12) to generate electrical power and to operate, on the other hand, in a motor mode in order to inject mechanical power from an electrical network and to drive the rotor (12),• aircraft turbomachine (T) characterized in that it comprises a control device (3) configured to determine the currents flowing in the stator (11) so that the rotor (12) provides an electric machine torque (TRQ) in accordance with a control torque (TRQ*), the control device (3) comprising a correction module (4) configured to attenuate an excitation of the torsional mode (Mt) of the transmission line (2), the control device (3) being configured to calculate the control torque (TRQ*) from the setpoint torque (TRQcons) and a correction torque (TRQcorr), the correction module (4) being configured to calculate the correction torque (TRQcorr) from a rotational speed (Nhp) of the propulsion shaft (Ahp) over a frequency range encompassing the estimated torsional frequency (Fte), designated “monitoring range (Ps)”.,

2. Aircraft turbomachine (T) according to claim 1 in which the transmission line (2) comprises at least one radial transmission shaft (22) and an accessory relay box (23).

3. Aircraft turbomachine (T) according to one of claims 1 to 2, in which, the speed (Nhp) of the propulsion shaft (Ahp) being linked to the speed of the electric machine (w) by a predetermined speed ratio (RV), the correction module (4) comprises a conversion block (40) configured to convert the speed (Nhp) of the propulsion shaft (Ahp) into a time speed of the electric machine (w), designated "time measurement (Mw)".

4. Aircraft turbomachine (T) according to claim 3, wherein the correction module (4) comprises a gain operator (43) having a gain (Kp) for multiplying the time measurement (Mw).

5. Aircraft turbomachine (T) according to one of claims 1 to 4, in which the correction module (4) comprises a high-pass filter (42) for cutting off frequencies below the monitoring range (Ps).

6. Aircraft turbomachine (T) according to claim 5, in which the high-pass filter (42) has a cut-off frequency corresponding to a lower limit Ftel of the monitoring range (Ps), the lower limit (Ftel) being between Fte / 3 and Fte / 2, Fte being the estimated torsion frequency.

7. Aircraft turbomachine (T) according to one of claims 1 to 6, in which the correction module (4) comprises a low-pass filter (41) for cutting off frequencies above the monitoring range (Ps).

8. Aircraft turbomachine (T) according to one of claims 1 to 7, in which the monitoring range (Ps) has a width of between 10 Hz and 50 Hz.

9. Method for correcting the torsion mode of the transmission line (2) of the aircraft turbomachine (T) according to one of claims 1 to 8, the electric machine (1) receiving a setpoint torque (TRQcons), the method comprising steps consisting of: • Calculating a correction torque (TRQcorr) from the rotation speed (Nhp) of the propulsion shaft (Ahp) over a frequency range encompassing the estimated torsion frequency (Fte), designated “monitoring range (Ps)”, and • Calculating a control torque (TRQ*) from the setpoint torque (TRQcons) and the correction torque (TRQcorr).

10. Computer program product comprising code instructions which, when these code instructions are executed by a unit of processing, lead said processing unit to implement a torsion mode correction method according to claim 9.

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