Method for monitoring the energy level of an electrical power source in a hybrid aircraft propulsion system

Abstract

The present invention relates to a method for monitoring the energy level of an electrical energy source capable of delivering a reference electrical power PRef for a reference duration DTref for a reference load level NRef. Said source comprises at least one electrical energy storage device and several sensors. The method includes acquiring parameters of said electrical energy source (10) via said sensors, and then calculating a main consumption duration DTprin during which said source is capable of supplying an electrical current carrying said reference electrical power PRef, as a function of said source parameters. Subsequently, a main display of key symbols (31) indicating said main consumption duration DTprin is provided to show an operator how long the source can supply said reference electrical power PRef.Abbreviated figure: figure 6.

Description

Title of the invention: Method for monitoring the energy level of an electrical power source in a hybrid aircraft propulsion system

[0001] The present invention lies in the technical field of hybrid propulsion systems for aircraft, and is more particularly related to the management of electrical energy sources of these hybrid propulsion systems.

[0002] The invention relates to a method for monitoring the energy level of an electrical power source of a hybrid propulsion system, as well as an electrical power source and an aircraft implementing this method.

[0003] An aircraft, and in particular a rotorcraft, may have one or more rotors capable of generating thrust and driven in rotation by a hybrid propulsion system. A rotorcraft may, for example, have a lift rotor that contributes to the aircraft's lift, or even its propulsion. A rotorcraft may also have an auxiliary rotor, for example a tail rotor, notably to counteract the yaw moment exerted by the lift rotor on the aircraft's fuselage and to control the aircraft's yaw movements. A rotorcraft may also have one or more propellers.

[0004] The hybrid propulsion system of such an aircraft comprises one or more thermal engines and at least one mechanical transmission chain arranged between, on the one hand, the rotor(s) and, on the other hand, the thermal engine(s).

[0005] A hybrid drive installation further comprises one or more electric machines to drive the rotor(s), via said at least one mechanical transmission chain.

[0006] A hybrid power plant also includes an electrical power source equipped with one or more storage devices, such as a battery or a supercapacitor. The electrical power source supplies electrical energy to each electric machine via an electrical transmission chain. Some electrical power sources may include rechargeable electrical energy storage devices.

[0007] It should be noted that the term "thermal engine" is used throughout this text for convenience to refer to any thermal engine that can be used in such a rotorcraft propulsion system, for example, turboshaft engines or piston engines. The term "thermal engine" is to be contrasted with the terms "electric motor" or "electric machine," which describe motors powered by electrical energy.

[0008] Depending on the operation of the hybrid drive system, the thermal engines and the electric machines can be used independently or in combination, simultaneously or sequentially.

[0009] However, the use of an electric machine to drive a rotor is subject to certain constraints, particularly related to the electrical power source. Indeed, the charge level of the electrical power source, corresponding to the amount of electrical energy it contains and which can be supplied to the electric machine in flight, is limited. This charge level of an electrical power source therefore allows the supply of electrical power for a limited time.

[0010] An electrical energy source with a maximum energy level is then sized to provide a predefined electrical reference power for a predefined nominal consumption time.

[0011] However, the electric machine may generate electrical power different from this reference electrical power, this electrical power being variable depending on the flight phase and the load on the electric machine. Thus, in the case of using electrical power lower than the reference electrical power, the duration of supply of such electrical power is greater than the nominal consumption time.

[0012] Furthermore, parameters of the electrical energy source, particularly its temperature and aging, can influence the value of this charge level and / or the electric current that the source is capable of supplying. In addition, an electrical energy source can be rechargeable and can therefore be recharged, at least partially, in flight, thereby increasing its charge level.

[0013] Consequently, it can then be difficult for an aircraft pilot to determine how long the electrical power source is capable of delivering the electrical power required by the hybrid propulsion system. The pilot's workload then increases in attempting to estimate this duration, which can be problematic in an emergency situation.

[0014] The present invention then aims to assist the pilot of an aircraft comprising a hybrid propulsion system in order to reduce his workload.

[0015] The present invention relates firstly to a method for monitoring the energy level of an electrical energy source, this electrical energy source being capable of delivering a reference electrical power PPe / for a predetermined reference duration DTRef for a predetermined reference load level NRef of the electrical energy source, and comprising: - at least one electrical energy storage device, - at least one sensor, and - a calculator.

[0016] The method according to the invention is remarkable in that it comprises the following steps: - acquisition of at least one parameter of the electrical energy source, via said at least one sensor, - calculation of a main consumption period DTprin during which the electrical energy source is capable of supplying an electric current carrying the reference electrical power PRef, as a function of at least one parameter of the electrical energy source, using the calculator, and - main display of main symbols indicating the main consumption time DTprin.

[0017] In this way, the method according to the invention makes it possible to monitor the electrical energy source using one or more parameters of this electrical energy source.

[0018] The electrical power source may, for example, belong to a hybrid propulsion system of an aircraft.

[0019] The electrical energy source may include a single energy storage device or several energy storage devices, possibly rechargeable. Such an energy storage device may include a battery, for example.

[0020] The electrical energy source also includes one or more sensors for monitoring the operation and condition of the electrical energy source by measuring the value of one or more parameters. The sensors allow for the measurement, firstly, of one or more parameters directly related to the electrical energy source itself and, secondly, of one or more parameters related to the electric current flowing through the electrical energy source.

[0021] The first parameter(s) can be chosen from a charge level, a temperature and an aging of the electrical energy source, while the second parameter(s) are chosen from an electrical intensity and an electrical voltage of an electrical current flowing in the electrical energy source.

[0022] The charge level takes, for example, the form of a coefficient expressed as a percentage equal to the current quantity of electrical energy contained in the electrical source divided by the maximum quantity of electrical energy it can contain. Aging is a coefficient representing the efficiency and / or yield of the electrical energy source as a function of its service life. Aging is, for example, equal to 1 when the electrical energy source is new and decreases over the life of the electrical energy source, in conjunction with the duration and conditions of use, for example, according to a predetermined law.

[0023] In addition, when the electrical energy source includes at least two electrical energy storage devices, the parameter(s) include one or more of the parameters mentioned above, relating to each of these storage devices.

[0024] The computer is connected to the sensors by a wired or wireless link and receives one or more signals carrying information relating to this or these parameters of the electrical energy source.

[0025] The computer then calculates the main consumption time DTprin using this or these parameters. The main consumption time DTprin can, for example, be determined using one or more laws or charts stored in a memory of the computer or in a memory connected to the computer. These laws or charts take into account, for example, the parameters of the electrical energy source, in particular its temperature and aging.

[0026] The main symbols may indicate the main consumption time DTprin by including the numerical value of this main consumption time DTprin. Alternatively or additionally, the main symbols may display this main consumption time DTprin in relation to the reference time DTRef. The main symbols may then include, for example, a bar graph, a disk, a scale, or other symbols.

[0027] The main symbols indicating the main consumption time DTprin can be displayed on a screen present on the electrical power source, or on a remote screen, for example present in the cockpit of an aircraft equipped with the monitored electrical power source.

[0028] Thanks to this main display of the main symbols, an operator, or even the pilot of an aircraft, can quickly visualize the main consumption time DTprin available for the electrical energy source, according to the parameter(s) of the source, and in particular its load level, and can then optimize the use of the electrical energy supplied by the electrical energy source.

[0029] In addition, the main symbols may include an alert zone corresponding to a predetermined final consumption time DT end during which the electrical energy source is able to supply an electric current carrying the reference electrical power PRef before the electrical energy source no longer contains electrical energy, and is therefore not able to supply electrical energy.

[0030] The alert zone is represented, for example, with a specific color, different from the color used for the other main symbols. This alert zone thus makes it possible to clearly and distinctly indicate the last percentages of electrical energy that the electrical energy source can supply.

[0031] The method according to the invention may also include an estimation of at least one additional consumption time DT comp during which the source electrical energy is capable of providing an electric current carrying a complementary electrical power Pcomp different from the reference electrical power PRef, depending on the parameter(s) of the electrical energy source and the complementary electrical power Pcomp, and a complementary display of complementary symbols indicating the duration of complementary consumption DT comp.

[0032] Indeed, the electrical energy source is not always used to deliver the reference electrical power PRef. Therefore, when the electrical energy source is used to deliver a different electrical power, and for example lower than the reference electrical power PRef, an operator knows that the electrical energy source can deliver such electrical power for a period exceeding the main consumption period DTprin, without any further information.

[0033] Similarly, if the electrical energy source delivers an electrical power greater than the reference electrical power PR ef, an operator visualizes, thanks to the complementary symbols, that the electrical energy source can deliver such electrical power for a period less than the main consumption period DTprin.

[0034] The additional display of supplementary symbols can thus indicate one or more supplementary consumption durations DTcomp associated respectively with one or more supplementary electrical powers Pcomp. This supplementary display advantageously allows the operator to have a more precise idea of ​​the duration for which the electrical energy source can supply such electrical power, even if this electrical power is not exactly equal to one of the supplementary electrical powers Pcomp whose supplementary consumption duration DTcomp is displayed. This supplementary electrical power Pcomp may, for example, correspond to a specific predetermined use.

[0035] The method according to the invention may also include a calculation of a value of electrical power received or delivered by the electrical energy source as a function of the parameter(s), and an additional display of the value of electrical power received or delivered.

[0036] This value of electrical power received or delivered can be determined using the second parameters of the electrical current flowing in the electrical energy source, namely the electrical voltage and the electrical current intensity. This value of electrical power received or delivered can also be determined using measurements at the level of the electrical machine that is supplied by the source, for example, using measurements of the motor torque of an output shaft of the electrical machine and the rotational speed of this shaft.

[0037] In this way, the operator can instantly know, on the one hand, whether the source receives an electric current to be recharged, or whether it supplies an electric current carrying electrical power, and on the other hand, the amount of energy it receives or delivers. The operator thus knows, for example, the electrical power delivered relative to the reference electrical power PRefd; the operator can estimate the duration of consumption of this delivered electrical power relative to the main consumption duration DTprin of which it is aware.

[0038] To facilitate awareness of the operation of the electrical energy source, when the electrical energy source receives electrical power, the value of the received electrical power is displayed with a first color, and when the electrical energy source delivers electrical power, the value of the delivered electrical power can be displayed with a second color distinct from the first color.

[0039] Furthermore, the electrical power source can equip an aircraft comprising a hybrid propulsion system and a lift rotor driven in rotation by the hybrid propulsion system via a mechanical transmission chain, the hybrid propulsion system comprising at least one thermal engine, at least one electric machine, and the electrical power source electrically connected to the electric machine(s) via an electrical link chain.

[0040] In this case, the method may include a determination of energy flow circulating in the mechanical transmission chain and the electrical link chain, as well as a transfer display, for example on a screen present in the aircraft cockpit, of transfer symbols with figures, representing respectively the lift rotor, the thermal engine(s), the electrical machine(s), and the electrical energy source, as well as arrows representing the energy flows between the lift rotor and respectively the thermal engine(s) and the electrical machine(s), as well as between the electrical energy source and the electrical machine(s).

[0041] In this way, the aircraft pilot has an overall view of the exchange of mechanical and electrical power in the hybrid propulsion system and to the lift rotor.

[0042] Alternatively or complementarily, the method according to the invention applied to an electrical power source of such an aircraft may comprise determining at least one characteristic of the aircraft, estimating at least one rate of descent and at least one achievable distance to the ground, using only electrical energy that the electrical power source can deliver, and displaying descent symbols, for example on a screen in the aircraft cockpit, representing at least one descent trajectory of the aircraft as a function of The aircraft's rate of descent and the distance the aircraft can reach for landing are indicated. Descent symbols include at least one aircraft descent path with an associated rate of descent and achievable distance.

[0043] The aircraft's rate of descent and the aircraft's attainable distance are determined based in particular on at least one parameter of the electrical power source, the electrical power supplied by the electrical power source to the electrical machine, the characteristic(s) of the aircraft, for example using laws or charts stored in a computer memory or a memory connected to the computer.

[0044] In this way, the pilot is aware of one or more descent trajectories allowing the aircraft to reach the ground, along with an achievable distance and the associated rate of descent, particularly for the purpose of landing. Such knowledge is especially useful when the lift rotor is driven solely by the electric machine(s) powered by the electrical power source, for example, in the event of a failure of the internal combustion engine(s).

[0045] Furthermore, during this estimation, several descent rates and several attainable distances can be estimated, each associated with a distinct electrical power output that the electrical energy source can deliver. The descent symbols then include several descent trajectories associated respectively with these descent rates and attainable distances. The descent symbols may also include a value for the electrical power that allows the descent rate and attainable distance associated with each displayed descent trajectory to be obtained.

[0046] An aircraft descent rate is, for example, determined using charts or formulas stored in a computer memory or in a memory connected to the computer. These formulas or charts, including polars characterizing the flight and performance of the aircraft, take into account one or more aircraft characteristics as well as the electrical power supplied by the electrical energy source to the electrical machine(s).

[0047] A descent path may consist solely of a slope based on the estimated rate of descent if the energy level of the electrical power source is sufficient for the source to deliver the electrical power associated with this estimated rate of descent until the aircraft reaches the ground. Alternatively, a descent path may consist of a first slope based on this estimated rate of descent, corresponding to flight during the duration of electrical energy consumption from the electrical power source, and a second slope at an autorotation rate of descent to the ground, corresponding to flight without engine power. An electrical energy reserve can also be specifically stored for consumption during the actual landing phase, for example to slow the aircraft's descent.

[0048] The aircraft characteristic(s) can be chosen from, for example, the aircraft height relative to the ground, the aircraft mass, the aircraft forward speed and the aircraft vertical speed.

[0049] Furthermore, the rate of descent and the achievable range can be adjusted based on the wind speed experienced by the aircraft. Indeed, in the case of a strong headwind, the achievable range will be reduced. The wind speed value can be determined and extracted from a weather report by the computer and / or be available from an avionics system on the aircraft.

[0050] The method according to the invention may also include determining a maximum reachable distance equal to the greatest of the previously estimated reachable distances, the maximum reachable distance being associated with an optimal rate of descent and optimal electrical power. Knowing this maximum reachable distance thus allows an aircraft pilot to estimate the most distant reachable landing point from their current position, regardless of the surrounding terrain.

[0051] The method according to the invention may then include a selection of a trajectory chosen from among the displayed descent trajectories and the descent symbols include a descent marker representing the rate of descent corresponding to the trajectory chosen on an artificial horizon instrument of the aircraft.

[0052] In this way, the aircraft pilot can check on the artificial horizon instrument whether the aircraft's actual rate of descent is consistent with the rate of descent associated with the chosen trajectory to reach a landing area.

[0053] Alternatively or complementarily, the method according to the invention may include a selection of a trajectory chosen from among the displayed descent trajectories and the descent symbols include a power reference representing the electrical power corresponding to the trajectory chosen on an aircraft power indication instrument.

[0054] In this way, the aircraft pilot can check on the power indicator instrument whether the power consumed by the aircraft complies with and / or is in accordance with the electrical power associated with the chosen trajectory for reaching a landing area. Such a power indicator instrument is, for example, a first limitation indicator or a collective pitch indicator.

[0055] The method may also include locating a current position of the aircraft, for example using a satellite positioning device, and the descent symbols include a display of at least one reachable distance superimposed on a map of the aircraft's environment from the position The aircraft's current map is stored, for example, in the aircraft's memory. The displayed achievable distance(s) are chosen from the estimated achievable distances.

[0056] The aircraft pilot can thus clearly visualize, on the map, the distance he can travel in the event of a failure of the internal combustion engine(s), using only the electrical energy that the electrical power source can provide. He can thus, for example, choose a landing zone for an emergency landing, depending on the distance reachable by the aircraft.

[0057] The present invention also relates to a source of electrical energy, comprising: - at least one electrical energy storage device, - at least one sensor, and - a calculator.

[0058] This electrical energy source is capable of delivering a reference electrical power PRef for a predetermined reference duration DTRef for a predetermined reference load level NRef and can apply the process as previously described, the computer being configured to implement this process.

[0059] The present invention also relates to an aircraft comprising a hybrid propulsion system and a lift rotor driven in rotation by the hybrid propulsion system via a mechanical transmission chain. The hybrid propulsion system comprises at least one internal combustion engine, at least one electric machine, and an electrical power source electrically connected to the electric machine via an electrical link chain. The electrical power source is capable of delivering a reference electrical power PPe / for a predetermined reference duration DTRef for a predetermined reference load level NRef and comprises at least one electrical energy storage device, at least one sensor, and a computer.

[0060] The electrical power source can apply the process as previously described, the computer being configured, for example, to implement this process. The computer can be dedicated to carrying out this process or shared to perform other functions in the aircraft, or even integrated into an aircraft avionics system.

[0061] The invention and its advantages will become apparent in more detail in the following description, with illustrative examples given by reference to the accompanying figures, which represent: - [Fig. 1], a view of an aircraft equipped with an electrical power source according to the invention, - [Fig. 2], a view of an aircraft equipped with an electrical power source according to the invention, - [Fig. 3], a synoptic diagram of a process according to the invention, and - Figures 4 to 11 show example views of the displays according to the method according to the invention.

[0062] Elements present in several separate figures are assigned one and the same reference.

[0063] Figures 1 and 2 represent examples of electrical power sources 10 equipping a hybrid propulsion system 20 of an aircraft 1.

[0064] Regardless of the embodiment, the electrical energy source 10 includes at least one electrical energy storage device 11,12, at least one sensor 13-17, and a computer 9.

[0065] According to a first example shown in [Fig. 1], the electrical energy source 10 comprises a single electrical energy storage device 11. According to a second example shown in [Fig. 2], the electrical energy source 10 comprises two electrical energy storage devices 11, 12 arranged electrically in parallel with each other.

[0066] In the context of the invention, an electrical energy source 10 may also include more than two electrical energy storage devices 11, 12. When a source 10 includes at least two electrical energy storage devices 11, 12, these may be electrically arranged in parallel with each other and / or in series.

[0067] A storage device 11,12 may include, for example, an electric battery, possibly rechargeable, or a supercapacitor.

[0068] Regardless of the examples shown, the electrical energy source 10 is capable of delivering an electric current carrying a reference electrical power PRef for a predetermined reference duration DTref for a predetermined reference load level NRef. The load level of the source 10 characterizes the amount of electrical energy that the source 10 contains. This electric current is characterized by an electrical intensity and an electrical voltage.

[0069] Of course, the electrical energy source 10 is also capable of delivering an electrical power different from the reference electrical power PRef. For example, the reference duration DTref can be equal to two minutes and the reference load level A7?e / can be equal to eighty percent (80%).

[0070] The sensors 13-17 of the electrical energy source 10 measure one or more parameters of this electrical energy source 10. In particular, the sensors 13-17 can be arranged at the electrical energy source 10 to measure one or more initial parameters directly related to the electrical energy source 10. properly speaking, as well as one or more second parameters relating to the electric current flowing in the source 10 of electrical energy.

[0071] Such a sensor 13-17 can provide a raw signal carrying raw measurements made by this sensor 13-17. Such a sensor 13-17 can also include an integrated computer in order to process these raw measurements, for example via filtering or conventional sampling, or even the application of transformations, and provide a processed signal carrying these raw measurements thus processed.

[0072] For example, an electrical energy storage device 11,12 may include a temperature sensor 13,13', optionally equipped with a thermocouple, to measure an internal temperature of this electrical energy storage device 11,12.

[0073] Complementarily or alternatively, an electrical energy storage device 11,12 may include a charge sensor 14,14' allowing the measurement of an electrical charge level of this electrical energy storage device 11,12, namely the amount of electrical energy it contains.

[0074] Complementarily or alternatively, an electrical energy storage device 11,12 may include an aging sensor 15,15' for measuring the aging level of this electrical energy storage device 11,12. Such an aging sensor 15,15' may, for example, include a computer configured to calculate the aging level of the electrical energy storage device 11,12 based on internal parameters, such as its internal resistance and state of charge. The aging level can be taken into account to determine the maximum electrical current that this electrical energy storage device 11,12 can supply.

[0075] Complementarily or alternatively, an electrical energy storage device 11,12 may include an intensity sensor 16,16', optionally equipped with an ammeter, to measure an electrical intensity of an electric current flowing in the electrical energy storage device 11,12, namely entering or leaving this storage device 11,12.

[0076] Complementarily or alternatively, an electrical energy storage device 11,12 may include a voltage sensor 17,17', optionally equipped with a voltmeter, to measure an electrical voltage across the terminals of the electrical energy storage device 11,12, corresponding to the electrical voltage of the electrical current entering or leaving the electrical energy storage device 11,12.

[0077] The computer 9 can be dedicated solely to the operation of the source 10. Alternatively, the computer 9 can be shared to perform other functions of the aircraft 1, or even be integrated into an avionics system 4 of the aircraft 1, as shown in [Fig. 2]. In both cases, the computer 9 is connected by wire or non-wired to sensors 13-17 from the source 10 of electrical energy to receive the signals emitted by sensors 13-17.

[0078] The computer 9 may include, for example, at least one processor and at least one memory, at least one integrated circuit, at least one programmable system, at least one logic circuit; these examples do not limit the scope given to the term "computer." The term "processor" may refer to a central processing unit known by the acronym CPU, a graphics processing unit (GPU), or a known digital unit.

[0079] The electrical energy source 10 may also include a display 15, for example a screen, for displaying several symbols containing one or more indications of the charge level of the electrical energy source 10. This display 15 may, for example, be located remotely in the cockpit of the aircraft 1, when the electrical energy source 10 is installed in a hybrid propulsion system 20 of this aircraft 1. Alternatively, the display 15 may be integrated into the electrical energy source 10.

[0080] In all cases, the display 15 is connected by wired or wireless means to the calculator 9.

[0081] Signals, electrical or optical, analog or digital, can then be transmitted, on the one hand, by the sensors 13-17 to the computer 9 and, on the other hand, by the computer 9 to the display 15.

[0082] As mentioned previously, the electrical power source 10 can equip a hybrid drive system 20 of an aircraft 1. The hybrid drive system 20 drives one or more rotors 2, for example a lift rotor, a tail rotor or a propeller, via a mechanical transmission chain 5. The mechanical transmission chain 5 may in particular include a main power transmission box 25.

[0083] The hybrid drive system 20 may include at least one thermal engine 21,22 mechanically connected to the mechanical transmission chain 5, as well as at least one electric machine 23,24 also mechanically connected to the mechanical transmission chain 5.

[0084] The electrical machine(s) 23,24 are electrically connected to the source 10 of electrical energy, via an electrical transmission chain 6, so as to be supplied by an electric current delivered by the source 10 of electrical energy.

[0085] Such an electric machine 23, 24 can operate in motor mode to transform electrical energy supplied by the electrical energy source 10 into mechanical energy transmitted to the lift rotor 2, via the mechanical transmission chain 5. The electric machine 23, 24 can also operate in generator mode to transform mechanical energy supplied by the internal combustion engine(s) 21, 22 and / or the lift rotor 2, via the transmission chain mechanical 5, in electrical energy transmitted to the source 10 of electrical energy via an electrical transmission chain 6, and intended to recharge the electrical energy storage device(s) 11,12 from the source 10.

[0086] In this way, the thermal engine(s) 21, 22 and the electrical machine(s) 23, 24 can jointly or independently drive the rotor 2 in rotation, via the mechanical transmission chain 5. The electrical energy source 10 can in particular be used to compensate for a failure of the thermal engine(s) 21, 22 by supplying the electrical machine(s) 23, 24 in order to drive the rotor 2 in rotation.

[0087] According to the example shown in [Fig. 1], the hybrid drive unit 20 comprises a thermal engine 21 and an electric machine 23. According to the example shown in [Fig. 2], the hybrid drive unit 20 comprises two thermal engines 21, 22 and two electric machines 23, 24. Alternatively, such a hybrid drive unit 20 may comprise one or more thermal engines 21, 22 and / or one or more electric machines 23, 24.

[0088] Aircraft 1 also includes an avionics system 4 that centralizes various information relating to the flight and operation of aircraft 1, obtained using conventional sensors and / or computers (not shown). The avionics system 4 can then display this information to a pilot of aircraft 1. This information centralized by the avionics system 4 includes, for example, the height above ground, the forward speed, and the vertical speed of aircraft 1 measured by dedicated sensors, respectively by a height sensor, such as a radiosonde, a forward speed sensor such as an anemometer, and a vertical speed sensor such as a variometer.

[0089] When the computer 9 is dedicated solely to the operation of the source 10, the computer 9 is connected by wired or wireless means to this avionics system 4. Such information relating to the flight and operation of the aircraft 1 can thus be transmitted to the computer 9, using electrical or optical, analog or digital signals.

[0090] In addition, instructions or a computer program can be stored in a memory of the computer 9 or in a memory linked to this computer 9. The computer 9 can then execute these instructions or this program to implement a method of monitoring an energy level of the electrical energy source 10.

[0091] Figure 3 shows a block diagram of this method for monitoring the energy level of an electrical energy source. This method may include the following steps.

[0092] First, the method includes an acquisition 110 of at least one parameter of the electrical energy source 10, carried out via sensors 13-17,13'-17'.

[0093] In this way, one or more first parameters relating to the electrical energy source 10, and in particular relating to the electrical energy storage device(s) 11, 12, and / or one or more second parameters relating to the electrical current flowing in the electrical energy source 10, and in particular relating to the electrical current flowing in the electrical energy storage device(s) 11, 12, are acquired. Signals carrying these parameters are, for example, transmitted by the sensors 13-17, 13'-17' to the computer 9, and possibly stored in a memory of the computer 9 or connected to the computer 9.

[0094] During this acquisition 110, if the electrical energy source 10 includes at least two electrical energy storage devices 11,12, an acquisition of at least one parameter for each of these storage devices 11,12 is carried out.

[0095] Following this acquisition 110, the method includes a calculation 120, performed by the computer 9 based on the parameter(s) of the previously acquired electrical energy source 10, of a main consumption time DTprin during which the electrical energy source 10 is capable of supplying an electric current carrying the reference electrical power PRef. The main consumption time DTprin is calculated using this or these parameters and one or more laws or charts stored in a memory of the computer 9 or in a memory connected to the computer 9. The main consumption time DTprin may, in particular, be equal to the amount of energy contained in the electrical energy source divided by the reference electrical power PRef, the amount of energy being defined by the load level of the source and possibly by its temperature, or even its aging.

[0096] Next, the method includes the main display 210, on the display 15, of main symbols 31 indicating the main consumption time DTprin.

[0097] The main symbols 31 can indicate the main consumption time DTprin by displaying this main consumption time DTprin in relation to the reference time DTRef. The reference time DTRef has been previously stored in a memory of the control unit 9 or in a memory linked to the control unit 9.

[0098] The main symbols 31 may have various forms, such as a bar graph, a disk, a scale, or others.

[0099] Figure 4 represents a first example of principal symbols 31 comprising a bar graph with eight bars, each representing a duration equal to one-eighth of the reference duration DTRef. The total number of bars thus represents the Reference duration DTRef corresponding to a load level of source 10 equal to or greater than the reference load level NRef

[0100] Thus, the filled squares jointly illustrate the main consumption duration DTprin, while the empty square(s) represent the amount of electrical energy from source 10 already consumed. According to this first example, the electrical energy source 10 has a main consumption duration DTprin equal to half the reference duration DTRef.

[0101] Figure 5 shows a second example of the main symbols 31 comprising a disk. A full disk, i.e., completely filled, represents the reference duration DTref corresponding to a load level of the source 10 equal to or greater than the reference load level NRef. When the main consumption duration DTprin is less than the reference duration DTref, then an angular sector appears, for example, empty, and corresponds to the amount of electrical energy from the source 10 already consumed. According to this first example, the electrical energy source 10 has a main consumption duration DTprin equal to three-quarters of the reference duration DTref.

[0102] Independently of these forms, the main symbols 31 may also include main indices 36 comprising numerical values ​​corresponding to different values ​​of the main consumption duration DTprin, as shown in Figures 4 and 5.

[0103] Furthermore, the main symbols 31 may include an alert zone 37 corresponding to a final consumption time DTfin during which the electrical energy source 10 is capable of supplying an electric current carrying the reference electrical power PRef before the electrical energy source 10 is no longer capable of supplying electrical energy. Such an alert zone 37 is shown hatched in Figures 4 and 5, and corresponds to one-eighth of the reference time DTref and is, for example, equal to 15 seconds. The final consumption time DTfin is predetermined, and therefore independent of the parameter(s) of the source 10. In practice, such an alert zone 37 may be represented with a distinctive color, for example orange or red, and distinct from the color used to fill the boxes or angular sectors of the graphical representation of this main symbol 31.

[0104] Thanks to this main display 210 of the main symbols 31, an operator or pilot of the aircraft 1 can clearly and quickly visualize the main consumption time DTprin during which the source 10 can supply the reference electrical power PRef. This allows them to optimize the use of the electrical energy contained in the electrical energy source 10, depending in particular on the duration and requirements of the flight until landing in the case of an aircraft 1. The pilot can, for example use part of this electrical energy, while retaining a quantity of electrical energy to compensate for a possible failure of one or more of the thermal engines 21,22.

[0105] This main display 210 advantageously takes into account the actual conditions of use of the electrical energy source 10 thanks to the parameters acquired from the source 10, and in particular its temperature, its charge level and its level of aging, as well as the electric current flowing in the source 10, whether it supplies an electric current to drive the rotor 2, or receives an electric current to recharge the electrical energy storage device(s) 11,12.

[0106] Furthermore, the method according to the invention may include an estimation 130 of at least one additional consumption time DTcomp during which the electrical energy source 10 is capable of supplying an electric current carrying an additional electrical power Pcomp different from the reference electrical power PRef. This estimation is performed by the computer 9, based on the parameter(s) of the electrical energy source 10 and the additional electrical power Pcomp. The method according to the invention may also include an additional display 220, on the display 15, of additional symbols 32 indicating this additional consumption time DTcomp associated with this additional electrical power Pcomp.Calculator 9 can, for example, perform a rule of three between the additional electrical power Pcomp, the reference electrical power PRef and the main consumption duration DTprin to estimate the additional consumption duration DTcomp.

[0107] The electrical power source is not always required to deliver the reference electrical power PRef. Therefore, it is not always obvious for an operator, or even a pilot of aircraft 1, to estimate the duration for which the electrical power source 10 is capable of delivering an electrical power different from the reference electrical power PRef, this lower electrical power being able to be higher or lower than the reference electrical power PRef.The additional display 220 of additional symbols 32 advantageously allows one or more additional consumption durations DTcomp associated respectively with one or more additional electrical powers Pcomp, which allows the operator to know exactly the duration of use of such additional electrical power Pcomp and to have a more precise idea of ​​the duration of use of an electrical power different from the reference electrical power PRef and an additional electrical power Pcomp, this electrical power being able to be located between an additional electrical power Pcomp and the reference electrical power PRef or between two additional electrical powers Pcomp.

[0108] Figure 6 represents the principal symbols 31, in the form of a graph with The display includes two supplementary electrical power levels: 36 main indices, 32 additional indices, and 32 supplementary indices for two additional electrical power levels Pcomp, respectively equal to 50% and 75% of the reference electrical power PRef. The supplementary display 32 also includes additional indices 38 with numerical values ​​corresponding to different values ​​of the supplementary consumption time DTcomp associated with these supplementary electrical power levels Pcomp.

[0109] Furthermore, the method according to the invention may include a calculation 140 of a value of electrical power received or delivered by the source 10 of electrical energy carried out by the calculator 9 as a function of at least one parameter of the source 10 of electrical energy, as well as an additional display 230, on the display 15, of this value 33 of electrical power received or delivered.

[0110] The operator or pilot of the aircraft 1 can thus easily see, on the one hand, whether the source 10 of electrical energy delivers electrical power to drive, for example, the lift rotor 2 or receives electrical power transmitted by the electrical machine(s) 23, 24, and, on the other hand, the value of this electrical power delivered or received.

[0111] Furthermore, to facilitate the operator's or pilot's understanding of the operating mode of the electrical power source 10, distinct colors may be used for the additional display 230 of this received or delivered electrical power value, depending on whether the electrical power source 10 receives or delivers this electrical power. A "-" sign and optionally a "+" sign may also be displayed in front of the received or delivered electrical power value, depending on whether the electrical power source 10 receives or delivers this electrical power.

[0112] The main symbols 31 shown in [Fig.6] also include the additional display 230 of an electrical power value with a "-" sign corresponding to the electrical power received by the electrical energy source 10.

[0113] In the specific case where the electrical power source 10 is fitted to an aircraft 1, the method may include a determination 150, by the computer 9, of the energy flows circulating in the mechanical transmission chain 5 and the electrical connection chain 6. The determination 150 essentially aims to determine the direction of energy flow in the mechanical transmission chain 5 and the electrical connection chain 6, namely between, on the one hand, the lift rotor 2 and, on the other hand, the internal combustion engine(s) 21, 22, the electrical machine(s) 23, 24, and between the electrical machine(s) 23, 24 and the electrical power source 10. The energy flow in the mechanical transmission chain 5 is unidirectional from the engine(s) thermal 21,22 towards rotor 2 whereas it can be bidirectional between the electrical machine(s) 23,24 and rotor 2. The energy flow in the electrical link chain 6 is bidirectional.

[0114] The directions of energy flow in the mechanical transmission chain 5 can be defined, for example, using torque measurements on the internal combustion engine(s) 21, 22 and on the electrical machine(s) 23, 24 using torque meters. The direction of energy flow in the electrical connection chain 6 can be defined using one or more second parameters relating to the electric current flowing in the electrical energy source 10.

[0115] The method then includes a transfer display 240, on the display 15, of transfer symbols 34 equipped with figures 51-54 representing respectively the lift rotor 2, the thermal engine(s) 21,22, the electrical machine(s) 23,24 and the electrical energy source 10 as well as arrows 61-63 representing the directions of circulation of these energy flows as shown in [Fig.7].

[0116] Fig. 7 represents the case of aircraft 1 of Fig. 1, during operation in which the engine 21, represented by a first figure 51, and the electric machine 23, represented by a second figure 52, jointly drive in rotation the lift rotor 2, represented by a third figure 53, the electrical energy source 10, represented by a fourth figure 54, electrically supplying the electric machine 23. The main symbols 31 can be displayed simultaneously with these transfer symbols 34 to indicate in particular the main consumption time DTprin.

[0117] Thanks to these transfer symbols 34, the pilot of the aircraft 1 can easily and instantly visualize the energy exchanges within the mechanical 5 and electrical 6 transmission chains, as well as the mode of operation of the electrical energy source 10, as a supplier or receiver of energy.

[0118] In the specific case where the electrical power source 10 is fitted to the aircraft 1, the method may include a determination 160 of characteristics of the aircraft 1, using the avionics system 4 and / or conventional sensors of the aircraft 1 capable of determining these characteristics such as the height of the aircraft 1 relative to the ground, its forward speed and its vertical speed for example.

[0119] Next, the computer 9 can perform an estimate 170 of at least one rate of descent, and then of at least one distance attainable by the aircraft 1 when the aircraft 1 uses only the electrical energy delivered by the electrical energy source 10. This estimate 170 is, for example, performed using dedicated laws or charts stored in a memory of the computer 9 or in a memory connected to the computer 9. For this purpose, the computer 9 receives signals carrying information relating to the previously measured characteristic(s) of the aircraft 1, as well as information relating to the parameter(s) of the electrical energy source 10 and can estimate one or more descent rates of the aircraft based on this or these characteristics of the aircraft 1, the parameter(s) of the electrical energy source 10 and one or more electrical powers that the electrical energy source 10 can supply to the electrical machine 23,24.

[0120] This or these rates of descent can be determined using nomograms or laws stored in a memory of the computer 9 or in a memory linked to the computer 9. These laws or nomograms may, for example, include polar curves characterizing the flight and performance of the aircraft 9.

[0121] The computer 9 applies the characteristics of the aircraft 1 and the electrical power supplied by the electrical energy source 10 to the electrical machine(s) 23, 24 to these laws or charts to deduce the rate of descent associated with this electrical power. A descent speed of the aircraft 1 using this electrical power and applying this rate of descent can be determined simultaneously by the computer 9 using these laws and charts as a function of the characteristics of the aircraft 1 and the electrical power supplied by the electrical energy source 10. This operation can be repeated several times with different electrical powers.

[0122] Next, one or more distances achievable to the ground by aircraft 1 are calculated by the computer 9 based on the estimated rate(s) of descent, the parameter(s) of the electrical power source 10, and the characteristic(s) of aircraft 1, in particular its height above the ground. The consumption time associated with the electrical power used to determine the rate of descent, and the corresponding descent speed for this electrical power and rate of descent, are also taken into account, as well as, optionally, a descent rate in autorotation of aircraft 1.

[0123] Indeed, a descent trajectory 40 can be constructed by the computer 9 to the ground to determine the reachable distance. The reachable distance is then equal to the horizontal distance between the starting point of this descent trajectory, namely the current position of the aircraft 1, and the arrival point of this descent trajectory on the ground.

[0124] This descent path 40 may only include a slope 45 depending on the estimated rate of descent if the consumption time associated with the electrical power used to determine the rate of descent allows the aircraft 1 to reach the ground directly at the associated descent speed.

[0125] Otherwise, the descent trajectory 40 comprises a first slope 46 according to this estimated rate of descent corresponding to a flight during this consumption time and the descent speed, as well as a second slope 47 at a rate of Autorotation descent to the ground corresponding to a flight without engine power. The autorotation descent rate can be predetermined before the flight and possibly adjusted according to the current mass of the aircraft 1, using laws or charts.

[0126] In addition, a reserve of electrical energy can be stored specifically for use during the actual landing phase, for example to slow down the descent of aircraft 1 at the moment of contact with the ground.

[0127] The estimation 170 may include one or more substeps, such as a construction substep 172 of this descent trajectory 40 and / or a determination substep 174 of the descent speed associated with the estimated descent rate and the corresponding electrical power. A calculation substep 175 of the consumption time associated with the electrical power corresponding to the estimated descent rate may also be performed. This calculation substep 175 is carried out identically to the estimation 130 of at least one additional consumption time DTcomp, considering the additional electrical power Pcomp to be equal to the electrical power corresponding to the estimated descent rate.

[0128] A calculation substep 176 of the rate of descent in autorotation can also be carried out by the computer 9, as a function of a current mass of the aircraft 1, provided for example by the avionics system 4 and a predetermined rate of descent in autorotation, stored in a memory of the computer 9 or in a memory linked to the computer 9.

[0129] The calculator 9 can thus estimate, during this estimation 170, a single descent rate relative to an electrical power, for example to the reference electrical power PRef, and the achievable distance corresponding to this descent rate. Alternatively, the calculator 9 can estimate, during this estimation 170, several distinct descent rates relative respectively to several distinct electrical powers, for example equal to the reference electrical power PRe / d to one or more complementary electrical powers Pcomp, and then the achievable distances corresponding to each of these descent rates.

[0130] Finally, a descent display 250, on the display 15, of descent symbols 35 showing at least one descent trajectory 40 of the aircraft 1 towards the ground 7 is made, as shown in [Fig.8].

[0131] The descent symbols 35 can then allow one or more trajectories 40 of the aircraft 1 to be displayed, constructed respectively with a pair comprising a rate of descent and the associated attainable distance.

[0132] The method may also include a determination 178 of a maximum attainable distance. This maximum attainable distance is equal to the greatest attainable distance among the estimated attainable distances and is associated with an optimal descent rate and optimal electrical power. The descent symbols 35 can then be used to display only a single, so-called "optimal" descent path 41 of aircraft 1, constructed with a combination that includes the optimal rate of descent and the maximum achievable distance. Alternatively, the descent symbols 35 can be used to display several descent paths 40 of aircraft 1, constructed respectively with a combination that includes a rate of descent and the associated achievable distance, including the optimal path 41 of aircraft 1. Figure 8 shows such an example of a descent path display 250.

[0133] For each displayed trajectory 40 of aircraft 1, the associated electrical power value(s), rate of descent and / or achievable range, and even the associated consumption time, can also be displayed. Furthermore, the rate of descent and achievable range can be corrected by the computer 9 according to the wind speed experienced by aircraft 1, using laws or charts stored in a memory of aircraft 1, taking this wind speed into account. This wind speed is, for example, provided by the avionics system 4.

[0134] Thanks to the descent display 250, the pilot can visualize, on the descent symbols 35, the descent path(s) 40 of the aircraft 1 permitted down to the ground 7 by the electrical energy available in the electrical energy source 10. Thus, in the event of a failure of the internal combustion engine(s) 21, 22, the pilot of the aircraft 1 can adapt the electrical power supplied by the electrical energy source 10 to reach a landing zone.

[0135] In this way, the method according to the invention advantageously makes it possible to increase the flight safety of the aircraft 1 following a failure of the internal combustion engine(s) 21, 22. The determination 160 of at least one characteristic of the aircraft 1 and the estimation 170 of at least one rate of descent and at least one attainable distance, as well as the steps that follow therefrom, can be carried out in parallel, in particular with the calculation 120 of the main fuel consumption time DTprin and the display of the descent 250. The estimation 170 can alternatively be carried out independently of these steps 120, 250, and therefore carried out following the acquisition 110 of at least one parameter of the source 10.

[0136] Furthermore, to assist the pilot in choosing a reachable landing zone following such a failure, the method may also include a localization 180 of a current position of the aircraft 1, obtained, for example, using a satellite positioning device onboard the aircraft 1, and the descent symbols 35 include a display of one or more reachable distances, or even only the maximum reachable distance, superimposed on a map of the environment of the aircraft 1 from the current position of the aircraft 1. The map of the environment overflown by the aircraft 1 has, for example, been previously stored in a memory of the aircraft 1. According to the example in [Fig. 9], two reachable distances are represented under The shape of circles 71, 72 centered on the aircraft's current position 1. A first circle 71 corresponds to the maximum achievable distance, while a second circle 72 corresponds to an achievable distance associated with the reference electrical power PRef. This achievable distance associated with the reference electrical power PRef can make it possible to avoid an obstacle, such as a mountain, by initially allowing a nearly horizontal flight using the reference electrical power PRef, and then to perform a descent towards the ground 7.

[0137] Finally, the method according to the invention may also include an assistance display 260 on the display 15, of assistance symbols 80 to help the pilot of the aircraft 1 to follow a descent trajectory 40.

[0138] The method may, for example, include a selection 190 of a trajectory chosen from among the descent trajectories 40 and the assistance symbols 80, and may include an artificial horizon 85 and a descent marker 82 representing the gradient rate corresponding to the chosen trajectory, as shown in [Fig. 10]. The descent marker 82 may be displayed on an artificial horizon instrument of the aircraft 1.

[0139] Alternatively or complementarily, the method may include the selection 190 of a trajectory chosen from among the descent trajectories 40 and the assistance symbols 80, which may include a power indicator 86 of the aircraft 1 and a power marker 83 representing the electrical power associated with the chosen trajectory, as shown in [Fig. 11]. The power marker 86 may be displayed on a power indicator instrument of the aircraft 1.

[0140] The selection 190 of a chosen trajectory from among the descent trajectories 40 can, for example, be carried out automatically by the computer 9, the chosen trajectory being, for example, the optimal trajectory. Alternatively, the selection 190 of a chosen trajectory from among the descent trajectories 40 can be carried out manually by the pilot using a selection device such as a touchscreen display, for example.

[0141] Naturally, the present invention is subject to numerous variations in its implementation. Although several embodiments have been described, it is understood that it is not conceivable to exhaustively identify all possible embodiments. It is, of course, conceivable to replace a described means with an equivalent means without departing from the scope of the present invention and the claims.

Claims

1. Demands Method for monitoring the energy level of an electrical energy source (10), said electrical energy source (10) being capable of delivering a reference electrical power (PR ef) for a predetermined reference duration (DTRef) for a predetermined reference load level (NRef) and comprising: - at least one electrical energy storage device (11,12), - at least one sensor (13-17), and - a calculator (9), said process comprises the following steps: - acquisition (110) of at least one parameter of said source (10) of electrical energy by means of said at least one sensor (13-17), - calculation (120) of a main consumption period (DTprin) during which said electrical energy source (10) is capable of supplying an electric current carrying said reference electrical power (PRef), as a function of said at least one parameter of said electrical energy source (10), and - main display (210) of main symbols (31) indicating said main consumption time (DTprin), characterized in that said electrical power source (10) equips an aircraft (1) comprising a hybrid propulsion system (20) and a lift rotor (2) driven in rotation by said hybrid propulsion system (20) via a mechanical transmission chain (5), said hybrid propulsion system (20) comprising at least one internal combustion engine (21, 22), at least one electrical machine (23, 24) and said electrical power source (10) electrically connected to said electrical machine (23, 24) via an electrical link chain (6), and said method comprises: - a determination (160) of at least one characteristic of said aircraft (1), - an estimate (170) of at least one rate of descent and at least one distance attainable using only electrical energy that can be delivered from said electrical energy source (10) as a function of said at least one parameter of said electrical energy source (10) and of said at least one characteristic of said aircraft (1), and - a descent display (250) of descent symbols (35) representing at least one descent path (40) of said aircraft (1) as a function of said rate of descent and said distance attainable.

2. A method according to claim 1, wherein said at least one parameter is selected from a charge level, a temperature, and an aging of said electrical energy source (10), as well as an electrical intensity and an electrical voltage of an electrical current flowing in said electrical energy source (10).

3. A method according to claim 2, wherein said electrical energy source (10) comprises at least two electrical energy storage devices (11,12), said at least one parameter comprises one or more parameters relating to each of said storage devices (11,12).

4. A method according to any one of claims 1 to 3, wherein said main symbols (31) include an alert zone (37) corresponding to a predetermined final consumption time (DTfin) during which said electrical energy source (10) is capable of supplying an electric current carrying said reference electrical power (PRef), before said electrical energy source (10) is not capable of supplying electrical energy.

5. A method according to any one of claims 1 to 4, wherein said method comprises an estimation (130) of at least one additional consumption time (DTcomp) during which said electrical energy source (10) is capable of supplying an electric current carrying an additional electrical power (Pcomp) different from said reference electrical power (PRefp) as a function of said at least one parameter of said electrical energy source (10) and said power supplementary electrical (Pcomp), and a supplementary display (220) of supplementary symbols (32) indicating said supplementary consumption time (DTcomp).

6. A method according to any one of claims 1 to 5 wherein said electrical power source (10) equips an aircraft (1) comprising a hybrid drive system (20) and a lift rotor (2) driven in rotation by said hybrid drive system (20) via a mechanical transmission chain (5), said hybrid drive system (20) comprising at least one internal combustion engine (21, 22), at least one electrical machine (23, 24) and said electrical power source (10) electrically connected to said at least one electrical machine (23, 24) via an electrical linkage chain (6), said method comprising a determination (150) of energy flow circulating in said mechanical transmission chain (5) and said electrical linkage chain (6), and a transfer display (240) of transfer symbols (34) having figures (51-54) representing respectively said lift rotor (2), said at least one internal combustion engine (21, 22),said at least one electrical machine (23,24) and said electrical energy source (10) and arrows (61-63) representing said energy flows between said lift rotor (2) and respectively said at least one heat engine (21,22) and said at least one electrical machine (23,24) as well as between said electrical energy source (10) and said at least one electrical machine (23,24).

7. A method according to any one of claims 1 to 6, wherein during said estimation (170), several descent rates and several attainable distances are estimated, being associated respectively with several distinct electrical powers that can be delivered by said source (10) of electrical energy, and several descent trajectories (40) are displayed.

8. A method according to claim 7, wherein said method comprises a determination (178) of a maximum attainable distance equal to the greatest of said attainable distances, said maximum attainable distance being associated with an optimal descent rate and an optimal electrical power.

9. A method according to any one of claims 7 to 8, in which said method includes a location (180) of a current position of said aircraft (1) and said descent symbols (35) include at least one reachable distance displayed as an overlay on a map of the environment of said aircraft (1) from said current position of said aircraft (1), said at least one reachable distance displayed being selected from said at least one estimated reachable distance.

10. Method according to claims 8 and 9, wherein said at least one reachable distance displayed comprises said maximum reachable distance and a reference reachable distance associated with said reference electrical power (PR ef).

11. A method according to any one of claims 7 to 10, wherein said method comprises a selection of a trajectory (190) chosen from said descent trajectories (40) and an assistance display (260) of descent symbols (35) comprising an artificial horizon (85) and a descent marker 82 representative of said rate of slope corresponding to said selected trajectory.

12. A method according to any one of claims 7 to 11, wherein said method comprises a selection (190) of a trajectory chosen from said descent trajectories (40) and an assistance display (260) of descent symbols (35) comprising a power indicator (86) of said aircraft (1) and a power marker representative of said electrical power corresponding to said chosen trajectory.

13. A method according to any one of claims 1 to 12, wherein said at least one descent trajectory (40) comprises a first slope (46) at said estimated rate of descent corresponding to a flight with electrical power supplied by said source (10) of electrical energy and a second slope (47) at an autorotation descent rate to the ground corresponding to a flight without engine power.

14. A method according to any one of claims 1 to 13, wherein the method comprises a construction step (172) of said descent trajectory (40) and / or a determination step (174) of a descent speed of said aircraft (1) associated with said estimated rate of descent and with said corresponding electrical power,

15.

16.

17. and / or a calculation step (175) of a consumption duration associated with said electrical power corresponding to said rate of descent. A method according to any one of claims 1 to 14, wherein said characteristics of said aircraft (1) are chosen from a height above the ground, a forward speed, a vertical speed of said aircraft (1). A method according to any one of claims 1 to 15, wherein said rate of descent and said attainable distance are corrected as a function of a wind speed experienced by said aircraft (1). Aircraft (1) comprising a hybrid propulsion system (20) and a lift rotor (2) driven in rotation by said hybrid propulsion system (20) via a mechanical transmission chain (5), said hybrid propulsion system (20) comprising at least one internal combustion engine (21, 22), at least one electrical machine (23, 24) and an electrical power source (10) electrically connected to said electrical machine (23, 24) via an electrical link chain (6), said electrical power source (10) comprising at least one electrical energy storage device (11, 12) and at least one sensor (13-17),said electrical energy source (10) being capable of delivering a reference electrical power (PRef) for a predetermined reference duration (DTRef) for a predetermined reference load level (NRef), characterized in that said electrical energy source (10) comprises a computer (9) configured to implement the method according to any one of claims 1 to 16.

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