Method for controlling a hybrid turbomachine incorporating a time-limited torque, associated hybrid turbomachine and aircraft comprising such a turbomachine.
A torque control method with a time-evolution limiting module addresses the abrupt gear changes in hybrid turbomachines, reducing mechanical stress and preventing over-torque during mode transitions.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- SAFRAN ELECTRICAL & POWER
- Filing Date
- 2024-05-07
- Publication Date
- 2026-05-15
AI Technical Summary
Switching an electric machine in a hybrid turbomachine between generator and motor modes causes abrupt changes in bearing surfaces of the gears, leading to mechanical damage, shocks, and over-torque issues.
Implement a torque control method with a time-evolution limiting module to manage the transition between operating modes, limiting the torque change between threshold values of opposite signs, and iteratively adjusting the torque value to minimize mechanical stress and over-torque.
The method effectively reduces mechanical stress and prevents over-torque during mode transitions, ensuring smooth operation and extended machinery life.
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Abstract
Description
Title of the invention: Method for controlling a hybrid turbomachine incorporating a time-limiting torque, associated hybrid turbomachine and aircraft comprising such a turbomachine. Technical field of the invention
[0001] The present invention relates to the field of hybrid turbomachinery for an aircraft. Technological background
[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.
[0003] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into account the factors impacting all phases of design and development in order to obtain aeronautical components and products that are less energy-intensive, more environmentally friendly, and whose integration and use in civil aviation have moderate environmental consequences, with the aim of improving the energy efficiency of aircraft.
[0004] In this context, it is known to mount an electric machine on a propulsion shaft of an aircraft turbomachine, for example a fan shaft, in order to obtain a hybrid turbomachine. Currently, the electric machine is configured either to operate in generator mode (drawing mechanical power from the propulsion shaft to generate electrical power) or configured to operate in motor mode (supplying mechanical power to the propulsion shaft by drawing electrical power, for example, from an electric battery).
[0005] The climate balance of hybrid turbomachinery is interesting.
[0006] With reference to [Fig. 1], the design of a hybrid turbomachine T with electrical assistance on the High Pressure shaft AHP and the Low Pressure shaft ABP is described in more detail. Thus, the electric machine MEHP (for example intended to operate in generator mode) is connected to the High Pressure shaft AHP of the turbomachine's propulsion by a transmission line LTMHP comprising, starting from the High Pressure shaft AHP, an internal transmission box 21 known by its designation IGB (for "Internal Gear Box" according to Anglo-Saxon terminology), a radial drive shaft 22 known by its designation RDS (for "Radial Drive Shaft" according to Anglo-Saxon terminology), an accessory transmission box 23, known by its designation AGB (for "Accessory Gear Box" according to Anglo-Saxon terminology) which allows mechanical connection with several accessories.
[0007] The accessory relay box 23 allows the connection of various types of accessories, for example, one or more electric machines. Currently, an electric machine dedicated to generator operation (to generate electricity for the aircraft's needs) is used, which can also be used in motor mode (for turbomachine starting) for certain applications. An air starter can be used.
[0008] The hybrid turbomachine T may also include an adapter box 24 to provide the mechanical interface between the electric machine 1 and the accessory relay box 23 (“AGB”). This adapter box 24 includes, in particular, gears RI, R2 to adapt the rotational speeds between the High Pressure shaft AHP of the turbomachine and the rotor of the electric machine ME.
[0009] Without going into detail, the MEBP electric machine is connected to the Low Pressure shaft AB P of the turbomachine propulsion by a transmission line LTMB P.
[0010] It should be noted that, alternatively, the turbomachine may provide an electric machine on the High Pressure shaft only or on the Low Pressure shaft only.
[0011] In this context, the Applicant is seeking solutions to offer hybrid turbomachines with an electric machine capable of operating alternately in generator mode and in motor mode. This makes it possible to eliminate the air starter (used only during startup), reduce the weight of the turbomachine, and ultimately improve the turbomachine's operability while meeting greater electrical requirements than those of aircraft currently in service.
[0012] A major difficulty lies in the fact that switching the electric machine from generator mode to motor mode or vice versa (changing the quadrant of the electric machine) results in a change in the bearing surfaces of the teeth of the electric machine's rotor and the opposing mechanical gear. In [Fig. 2], a zone ZON is shown, corresponding to a contact zone between the tooth bearing surfaces of the two gears RI, R2 during operation in generator mode, illustrated by the arrow GEN. The arrow MOT represents motor mode, and it can be seen that if there is a switch to motor mode, then the inter-tooth clearance J must be traversed, and other tooth bearing surfaces will then be in contact.
[0013] This abrupt change is likely to generate significant shocks on the bearing surfaces of the gear teeth, damaging the long-term mechanical strength of the machine and the transmission chain. This abrupt change can also generate low frequency oscillations as well as over-torque relative to the torque control, are also damaging.
[0014] Also, an objective of the invention is to propose a solution implementing an electric machine capable of operating alternately in generator mode and in motor mode within a hybrid turbomachine, while limiting at least one of the adverse effects described above. Summary of the invention
[0015] To this end, a method for controlling a hybrid turbomachine is proposed, said turbomachine comprising a drive shaft, an electric machine configured to operate in a generator operating mode or a motor operating mode, a control device for the electric machine and a mechanical transmission line between the shaft and the electric machine, said mechanical transmission line comprising at least two gears having teeth capable of being in contact via corresponding bearing faces in an operating mode of the electric machine, characterized in that it comprises the following steps: a) provide the control device of the electric machine with a torque command whose value is adapted to change the operating mode of the electric machine, this implying that the corresponding bearing faces of the teeth of said at least two gears of the mechanical transmission line are made to change, said control device comprising a torque time evolution limiting module configured to limit the time evolution of the torque between two threshold values, of opposite signs, of said torque; b) retrieve a torque value at the output of the torque time evolution limiter and inject said torque value into the input of the torque time evolution limiter so as to obtain, at the output of said limiter, a renewed torque value; c) repeat step b) N times, where N is a non-zero natural number, so that when the torque value injected into the input of the torque time evolution limiter is between the two threshold torque values of said limiter, the renewed torque value at the output of said limiter has a time evolution limited by said limiter applied to it by reference to the torque value injected into the input of the limiter.
[0016] Thus, thanks to the process according to the invention, it is possible to limit or even avoid over-torques with respect to the torque control, to attenuate shocks at the level of the teeth.
[0017] The process according to the invention may comprise one or more of the steps below, taken individually or in combination with each other:
[0018] - when the electrical machine (ME) is in a generator operating mode where the torque of the electric machine is by convention negative, the torque control (CEEC) implemented in step a) is then able to switch the electric machine (ME) to the motor operating mode where the torque of the electric machine is by convention positive and in this case, a first threshold value (Vseuii_i) of the torque is negative and a second threshold value (Vseuii_2, V*seuii_i) of the torque is positive;
[0019] - when the electric machine is in a motor operating mode where the torque of the electric machine is by convention positive, the torque control implemented in step a) is then able to switch the electric machine to generator mode in which the torque of the electric machine is by convention negative and in this case, a third threshold value of the torque is positive and a fourth threshold value of the torque is negative;
[0020] - the second threshold value is identical to the third threshold value and the fourth the threshold value is identical to the first threshold value;
[0021] - the torque control provided in step a) is derived from a power control divided by the rotational speed of the electrical machine;
[0022] - the electric machine is installed on a high-pressure shaft of the turbomachine;
[0023] - the electric machine is installed on a low pressure shaft of the turbomachine;
[0024] - the method is implemented for two electrical machines, a first machine an electric machine mounted on a high-pressure shaft of the turbomachine and a second electric machine mounted on a low-pressure shaft of the turbomachine.
[0025] The invention also relates to a hybrid turbomachine comprising a drive shaft, an electric machine configured to operate in a generator operating mode or a motor operating mode, an electric machine control device and a mechanical transmission line connecting the shaft to the electric machine, said mechanical transmission line comprising at least two gears having teeth capable of being in contact via corresponding bearing faces in an operating mode of the electric machine, characterized in that the electric machine control device is configured to receive a torque command whose value is adapted to change the operating mode of the electric machine, this implying that the corresponding bearing faces of the teeth of said at least two gears of the mechanical transmission line are made to change,the control device comprising a torque time evolution limiting module configured to limit the time evolution of the torque between two threshold values, of opposite signs, of said torque and the control device comprising a feedback loop from the output of the torque time evolution limiting module to an input of said module, torque time evolution limiter, such that when the torque value injected into the input of the torque time evolution limiter is between the two torque threshold values of said limiter, the torque value renewed at the output of said limiter has a time evolution limited by said limiter applied, by reference to the torque value injected into the input of the limiter.
[0026] The invention also relates to an aircraft comprising a hybrid turbomachine as defined above. Brief description of the figures
[0027] The invention will be better understood with the aid of the following description, given solely by way of example and made with reference to the accompanying drawings in which: - The [Fig.1], commented on previously, is a schematic representation of a hybrid Low Pressure BP and High Pressure HP turbomachine; - The [Fig.2], commented on previously, represents the meshing between two gears belonging to a transmission line between a shaft of the turbomachine and an electric machine of the turbomachine; - Fig. 3 is a schematic representation of a method for controlling a hybrid turbomachine according to an example of an embodiment of the invention; - Fig. 4 is a diagram of an electrical machine control device, said device including in particular a time-evolution torque limiting module capable of being used to implement an example of the invention; - Fig. 5 illustrates in a generic way the effect provided by an example of the invention on the evolution of the control torque transmitted to the electric machine as a function of time; - Fig. 6 represents, for a given setting, measurements of the evolution of the control torque Cl transmitted to the electric machine and the measured torque Cm at the level of the electric machine in response to a torque command in the form of a step, in this case a positive step likely to represent operation in motor mode of the electric machine, for example to ensure the start-up of the hybrid turbomachine; - Fig. 7 represents measurements similar to those in Fig. 6, with a different setting; - Figure 8 represents, for a given setting, measurements of the evolution of the control torque Cl transmitted to the electric machine and the measured torque Cm at the level of the electric machine in response to a torque command in the form of a step, in this case a negative step likely to represent the transition from motor mode operation to generator mode of the electric machine. - Fig. 9 represents measurements similar to those in Fig. 8, with a different setting; - The [Fig. 10] is a diagram of an electrical machine control device according to another embodiment, said device including in particular a time-evolution torque limiting module capable of being used to implement an example of the invention. Detailed description of the invention
[0028] Figure 3 schematically represents the different stages of a method for controlling a hybrid turbomachine according to the invention.
[0029] The control method applies to a hybrid turbomachine, said turbomachine comprising an AHP, ABP shaft, a High Pressure Electric Machine MEhp or a Low Pressure Electric Machine MEBP or both a High Pressure Electric Machine MEHP and a Low Pressure Electric Machine MEHP configured to operate in a generator operating mode or a motor operating mode, a DCEHP, and / or DCEBP control device of the or each MEHP, MEBP electric machine and a LTMHP, LTMBP mechanical transmission line between the propulsion shaft AHP, ABP and the associated electric machine, said LTMhp line,LTMbp mechanical transmission comprising (for example in the adapter housing 24 for interfacing between the MEHP electric machine and the accessory relay housing 23) at least two gears with teeth capable of contacting each other via corresponding bearing faces in an operating mode of the electric machine (generator or motor).
[0030] The method includes a step a) of providing the control device DCEhp, DCEbp of the electric machine MEHP, MEBP with a torque command Ceec,hp, CEEc,bp (in [Fig. 3], the command CEec refers interchangeably to either the command for the Low Pressure or High Pressure electric machine) whose value is adapted to change the operating mode (quadrant change) of the electric machine MEHP, MEBP (from generator mode to motor mode or vice versa, from motor mode to generator mode). This implies that the corresponding bearing faces of the teeth of said at least two gears of the mechanical transmission line are changed. Therefore, the control device DCEHP, DCEBP includes a torque time-evolution limiting module MLC configured to limit the time evolution of the torque between two threshold values of said torque.These threshold values have opposite signs, in order to manage the change in sign of the torque of the electric machine linked to the change in operating mode (quadrant change).
[0031] The method then includes a step b) consisting of retrieving a torque value from the output of the MLC time-evolution torque limiter and injecting said torque value into the input of the MLC time-evolution torque limiter so as to obtain, at the output of said MLC limiter, a renewed torque value. Thus, after a first pass of the CEEC torque command through the MLC limiter module, this command becomes a TRQ* torque command for the rest of the DCE control device and the associated value is reinjected into the MLC limiter module.
[0032] The process then includes a step c) consisting of repeating step b) N times, where N is a non-zero natural number. This step simply clarifies the fact that the process is iterative.
[0033] The constraint imposed by the limiter is therefore managed dynamically.
[0034] Ultimately, steps a), b), and c) ensure that, when the torque value injected into the input of the MLC torque time evolution limiter is between the two torque threshold values of said MLC limiter, the torque value renewed at the output of said MLC limiter is subjected, by reference to the torque value injected into the input of the MLC limiter, to a time evolution (considerable as a slope) limited by said limiter: there is therefore a change in the time evolution of the torque. The threshold values must be adapted to the technical characteristics of the hybrid turbomachine, as must the limit to be applied to the time evolution of the torque. The MLC limiter module thus makes it possible to control the slope of the torque evolution through successive iterations and therefore to achieve the required torque while limiting shocks during the change of support faces.This module thus reduces mechanical stress while limiting or preventing any over-torque relative to the torque demand. A concrete example is provided later.
[0035] The MEHP electric machine can be installed on a high-pressure shaft AHp of the turbomachine. Alternatively, the MEBP electric machine can be installed on a low-pressure shaft ABP of the turbomachine. According to yet another embodiment, the method according to the invention can be implemented for two MEHP, MEBP electric machines, a first MEHP electric machine mounted on the high-pressure shaft Ahp of the turbomachine and a second MEBP electric machine mounted on the low-pressure shaft ABP of the turbomachine.
[0036] An example of an embodiment of a DCEHP, DCEBP control device equipped with an MLC torque time evolution limiting module that can be implemented within the framework of the invention is illustrated in [Fig. 4]. The control device is part of the hybrid T turbomachine.
[0037] The DCEHP, DCEBP control device is configured to determine the currents flowing in the stator of the electric machine so that the rotor of the machine The electrical system provides an electrical machine torque TRQ corresponding to a control torque TRQ*. The control device includes a unit for determining a setpoint current Iq* from the control torque TRQ*. The control device also includes a unit for determining a direct setpoint current Id*. The setpoint currents Iq*, Id* are converted into setpoint voltages 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 of the electrical machine ME (which can refer to either the High Pressure electrical machine MEHP or the Low Pressure electrical machine MEBP).In this example, currents labc are measured at the stator of the electric machine ME and are represented vectorially by a forward current Id and a quadrature current Iq, based on knowledge of an angular position 0 of the rotor relative to the stator. The electric machine ME is controlled via a vector control dq. The conversion unit 33 determines the setpoint voltages Vq*, Vd* based on knowledge of the rotor speed w relative to the stator in order to achieve flux deflux. According to one aspect, the angular position 0 of the rotor 12 relative to the stator is obtained by a monitoring unit 36, which can be connected to an angular sensor 37 or to an observation unit (not shown) that allows the angular position 0 to be determined from the measurement of the control currents labc.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 (PWM signal for example) to an inverter 35 supplying the electrical machine ME, in particular, its stator.
[0038] The general structure and components of the DCEHP, DCEBP control device described above are known to those skilled in the art and are not presented in more detail.
[0039] According to the invention, the DCEHP, DCEBP control device comprises a torque time evolution limiting module MLC configured to limit the time evolution of the torque between two threshold values of opposite signs.
[0040] For example, the negative threshold Vseuii_i is applied when switching from generator mode to motor mode. The positive threshold Vseuii_2 is used when switching from motor mode to generator mode. The negative threshold Vseuii_i can have a value that is strictly opposite to that of the positive threshold Vseuii_2, or it can have a completely different value.
[0041] More generally, we can also define other threshold values V*seuii_i (when switching to motor mode) and V*seuii_2 (when switching to the mode generator) used as switching hysteresis from a slow time evolution of torque (low slope) to a fast time evolution of torque (high slope).
[0042] Thus, in the most general way, we can then define a first threshold Vseuii_i, a second threshold V*seuii_i, a third threshold Vseuii_2 and a fourth threshold V*seuii_2. When hysteresis is activated, V*seuii_i is different from Vseuii_2 and V*seuii_2 is different from VSeuii_i. If hysteresis is not applied, then V*seuii_i = Vseuii_2 (the second threshold is identical to the third threshold) and V*seuii_2 = Vseuii_i (the fourth threshold is identical to the first threshold).
[0043] Furthermore, the DCE control device includes a BRE feedback loop at the output of the MLC time evolution torque limiter module to an input of said time evolution torque limiter module.
[0044] Figure 5 generally represents the effect provided by the invention. This figure shows the evolution of the control torque TRQ* to the electric machine (on the ordinate; this could just as easily represent the torque actually supplied by the electric machine) as a function of time (abscissa).
[0045] At the initial time (t = 0), the electric machine operates in generator mode (negative torque), and a torque command CEEC (referring interchangeably to CEEC, hp or CEEC, bp) is supplied to the DCE control device to switch to motor operating mode (positive torque). The two threshold values of the time evolution limiting module that may come into play are then Vseuii_i and V*seuii_i. Since these thresholds have opposite signs, we then have Vseuii_i < 0 (generator) and V*seuii_i > 0 (motor). Between these two threshold values, the time evolution of the torque is limited.
[0046] At a later time, the electric machine operates in motor mode (positive torque), and a CEEC torque command is provided to the DCE control device to switch to generator mode (negative torque). The two threshold values of the time evolution limiting module that may then come into play are Vseuii_2 and V*seuii_2. Since these thresholds have opposite signs, we then have Vseuii_2 > 0 (motor) and V*seuii_2 < 0 (generator). Between these two threshold values, the time evolution of the torque is limited.
[0047] It should be noted that on the representation of [Fig.5], it is also possible to implement another time evolution limiting module for torque, but outside the area between the two threshold values, thus limiting this evolution to a given value in a perfectly controlled manner.
[0048] Concrete tests were carried out and various test results are presented in support of Figures 6 to 9.
[0049] Figures 6 and 7 show a case with a positive step of torque starting from the play recovery zone.
[0050] The CEEC torque control corresponds to the torque step. The Cl curve corresponds to the electromagnetic torque control (it can be associated with the TRQ* control of [Fig. 4]). The Cm curve corresponds to a mechanical torque measurement taken on the electrical machine. There is no overtorque, as can be seen by comparing the measured torque values (Cm curve) with the C^c torque control.
[0051] Figure 7 shows the torque evolution over time for the same positive torque step as Figure 6, but with the torque time evolution limited to a value twice as high. This is the only difference in test conditions compared to Figure 6. The response time is better in Figure 7 (approximately 160 ms), but compared to Figure 6 (approximately 230 ms), there is an over-torque relative to the CEEC torque control, which is unacceptable under certain conditions.
[0052] In this case, we can choose the setting of [Fig.6] because it avoids any over-torque compared to the torque control, while keeping an acceptable response time.
[0053] Figures 8 and 9 illustrate an example with a negative torque step, starting from a significant positive value and ending with an equally significant negative torque value. This can represent a transition from motor to generator mode of the electric machine (a quadrant change). The torque limitation is the same in both tests. Only the value V*seuii_2 was changed between the two tests.
[0054] More specifically, on [Fig.8], we observe an over-couple.
[0055] In [Fig. 9], by decreasing the value of V*threshold_2, the over-torque is largely attenuated and there is virtually no overshoot. This is achieved, however, at the cost of a longer response time, which nevertheless remains acceptable.
[0056] For the most common types of hybrid turbomachines, it can nevertheless be provided that, when the electric machine ME is in a generator operating mode (where the torque of the electric machine is by convention negative), the torque control C^c implemented in step a) is then able to switch the electric machine ME to the motor operating mode (where the torque of the electric machine is by convention positive) and in this case, to carry out the changes in the time evolution of torque at the threshold value Vseuii_i and at the threshold value V*seuii_i. This makes it possible to limit or even avoid any overtorque while maintaining an acceptable response time.
[0057] Similarly, for the most common types of turbomachinery, it can be expected that, when the electric machine ME is in motor operating mode (where the electric machine torque is conventionally positive), the torque control Ceec implemented in step a) is capable of switching the electric machine ME to generator operating mode (in which the electric machine torque is conventionally negative). In this case, the changes in the time evolution of the torque should be made at the threshold value Vseuii_2 of the torque and at the threshold value of the torque V*seuii_2-
[0058] Another embodiment of a DCEHp, DCEBP control device equipped with a time-evolving torque limiting module (MLC) that can be implemented within the scope of the invention is illustrated in [Fig. 10] under the generic designation DCE. Here, a power command (Ceec) is obtained and divided, in the DIV module, by the rotational speed of the electric machine. This results in a control torque output from the DIV module, which then enters as a command into the MLC torque limiting module, as shown in [Fig. 4]. The rest is identical to what occurs in the control device described previously in support of [Fig. 4]. Thus, it is understood that in this variant, the torque command provided in step a) of the method confirming the invention is derived from a power command to which the rotational speed of the electric machine has been divided.
[0059] Additional regulation can also be added to limit the possible excitation effects (resonance) of the torsion mode of the radial transmission shaft.
Claims
Demands
1. A method for controlling a hybrid turbomachine, said turbomachine comprising a propulsion shaft (AHP, ABP), an electric machine (MEHP, MEBP) configured to operate in a generator operating mode or a motor operating mode, a control device (DCEHP, DCEBP) for the electric machine and a mechanical transmission line (LTMHP, LTMBP) between the shaft (AHP, ABP) and the electric machine (MEhp, MEbp), said mechanical transmission line (LTMHP, LTMBP) comprising at least two gears having teeth capable of contacting each other via corresponding bearing faces in an operating mode of the electric machine, characterized in that it comprises the following steps: a) providing the control device (DCEHP, DCEBP) for the electric machine with a torque command (Ceec, hp, Ceec, bp) whose value is adapted to change the operating mode of the electric machine (MEHP, MEBP),This implies that the corresponding bearing faces of the teeth of said at least two gears of the mechanical transmission line are brought to change, said control device (DCEHP, DCEBP) comprising a torque time evolution limiting module (MLC) configured to limit the time evolution of the torque between two threshold values (VSeuili_i, V*seuiLi; VseuiL2, V*seuiL2), of opposite signs, of said torque; b) retrieve a torque value at the output of the torque time evolution limiting module (MLC) and inject said torque value at the input of the torque time evolution limiting module (MLC) so as to obtain, at the output of said limiting module (MLC), a renewed torque value; c) repeat step b) N times, where N is a non-zero natural number, so that when the torque value injected into the input of the time evolution torque limiter (MLC) is between the two threshold torque values of said limiter (MLC), the torque value renewed at the output of said limiter (MLC) has a time evolution limited by said limiter applied, by reference to the torque value injected into the input of the limiter (MLC).
2. The method according to claim 1, wherein when the electrical machine (EM) is in a generator operating mode where the torque of the electric machine is by convention negative, the torque control (CEEC) implemented in step a) is then able to switch the electric machine (ME) to the motor operating mode where the torque of the electric machine is by convention positive and in this case, a first threshold value (Vseuii_i) of the torque is negative and a second threshold value (Vseuii_ 2- V*seuii_i) of the torque is positive.
3. A method according to any one of the preceding claims, wherein when the electric machine (EM) is in a motor operating mode where the torque of the electric machine is by convention positive, the torque control (CEEC) implemented in step a) is then capable of switching the electric machine (EM) to the generator operating mode in which the torque of the electric machine is by convention negative and in this case, a third threshold value (Vseuii_ 2) of the torque is positive and a fourth threshold value (Vseuii_ 1, V*seuii_ 2) of the torque is negative.
4. A method according to the preceding claim, wherein the second threshold value (Vseuii_ 2) is identical to the third threshold value and the fourth threshold value (Vseuii_ 1) is identical to the first threshold value.
5. A method according to any one of the preceding claims, wherein the torque control provided in step a) is derived from a power control divided by the rotational speed of the electric machine.
6. A method according to any one of the preceding claims, wherein the electric machine (MEHP) is installed on a high-pressure shaft (Ahp) of the turbomachine.
7. A method according to any one of claims 1 to 5, wherein the electric machine (MEBP) is installed on a low-pressure shaft (ABP) of the turbomachine.
8. A method according to any one of claims 1 to 5, characterized in that it is implemented for two electric machines (MEHP, MEBP), a first electric machine (MEHP) mounted on a high-pressure shaft (AHP) of the turbomachine and a second electric machine (MEBP) mounted on a low-pressure shaft (ABP) of the turbomachine.
9. Hybrid turbomachine comprising a propulsion shaft (AHP, ABP), an electric machine (MEHP, MEBP) configured to operate in a generator operating mode or a motor operating mode, a control device (DCEHP, DCEBP) for the electric machine and a mechanical transmission line (LTMHP, LTMBP) connecting the shaft to the electric machine, said mechanical transmission line (LTMhp, LTMbp) comprising at least two gears having teeth capable of contacting each other via corresponding bearing faces in an operating mode of the electric machine, characterized in that the control device (DCEHP, DCEBP) for the electric machine is configured to receive a torque command (CEEC, hp, Ceec, bp) whose value is adapted to change the operating mode of the electric machine,This implies that the corresponding bearing faces of the teeth of said at least two gears of the mechanical transmission line are to change, the control device (DCEHP, DCEBP) comprising a torque time evolution limiting module (MLC) configured to limit the time evolution of the torque between two threshold values (V threshold, 1, V*Seuii_ 1, Vseuii_ 2, V*seuii_ 2), of opposite signs, of said torque, and the control device (DCE) comprising a feedback loop (BRE) at the output of the torque time evolution limiting module (MLC) to an input of said torque time evolution limiting module, such that when the torque value injected at the input of the torque time evolution limiting module (MLC) is between the two torque threshold values of said limiter (MLC), the renewed torque value at the output of said limiter (MLC) is applied, by reference to the torque value injected at the input of the limiter (MLC),a temporal evolution limited by said limiter.
10. Aircraft comprising at least one hybrid turbomachine according to the preceding claim.