METHOD FOR FLIGHT AUTHORIZATION OF AN AIRCRAFT WITH A HYBRID PROPULSION SYSTEM WITH AT LEAST ONE ELECTRIC MOTOR AND AT LEAST ONE INTERNAL COMBUSTION ENGINE

Description

[0001] The present invention relates to a method for authorizing the flight of an aircraft having a hybrid power plant equipped with at least one electric motor and at least one thermal engine, and an aircraft applying this method.

[0002] An aircraft may comprise a power plant equipped with at least one electric motor and at least one thermal engine. In particular, a rotorcraft may be equipped with such a power plant to rotate at least one rotor, possibly via at least one power transmission box.

[0003] An electric motor may take the form of an electric machine capable of operating only in motor mode, during which the electric motor provides mechanical power, or an electric machine capable of operating in an electric motor mode and in an electric generator mode, during which the electric motor generates electrical energy. An electric motor is usually electrically connected to a source of electrical energy. The source of electrical energy may comprise a plurality of electrical accumulators arranged in one or more electric batteries. An electric accumulator is also sometimes referred to as a cell.

[0004] A heat engine is an engine equipped with a combustion chamber supplied with fuel and an oxidizer, such as a turboshaft engine or a piston engine.

[0005] For example, a rotorcraft may have a thermal engine and an electric motor, each capable of driving a main lift rotor. The electric motor may, in particular, have the function of providing mechanical power to the main rotor in the event of a thermal engine failure. Such a rotorcraft then combines the advantages of a single-engine rotorcraft, while offering the safety level of a twin-engine rotorcraft thanks to the assistance provided by the electric motor in the event of a thermal engine failure. The electric motor can in fact provide mechanical power to the main rotor, following the failure of the thermal engine, for a period of a few minutes after the possible failure of the thermal engine. This supply of mechanical power can allow the rotorcraft to reach a safe landing area.When flying over a city, such a power plant can increase safety for people by possibly allowing the rotorcraft to reach a landing area located outside the city, for example.

[0006] The use of an electric motor within an aircraft power plant is therefore interesting, particularly to optimize the safety of the aircraft in the event of a thermal engine failure. However, this electric motor requires the use of an electrical network electrically connected to the electric motor. This electrical network is particularly sized so that the electric motor provides the desired mechanical power to carry out the intended mission. The electrical network of a rotorcraft with a hybrid engine is, for example, sized so that the electric motor provides a predetermined mechanical power for at least a predetermined duration in the event of a thermal engine failure. Such an electrical network is, however, likely to be deficient and not allow the electric motor to perform the desired function.

[0007] Document WO2020 / 156079 A1 describes a method and a device for monitoring an electric battery of an aircraft. This method comprises acquiring values ​​of performance parameters of the electric battery, these parameters comprising at least a number of operating cycles, the smallest electrical voltage across a cell of the electric battery, and a difference between electrical voltages across the cells of the electric battery. The difference between electrical voltages across the cells of the electric battery is measured between the electrical voltage of the cell of the electric battery having the greatest electrical voltage across its terminals and the electrical voltage of the cell of the electric battery having the smallest electrical voltage across its terminals.

[0008] The method comprises a step of determining a state identifier as a function of the values ​​of the performance parameters, the aircraft being controlled in flight to follow a strategy which is a function of this state identifier.

[0009] WO2018 / 171495 describes a battery management system. A management chip calculates health information for a battery cell module based on electrical current, electrical voltage, and temperature data.

[0010] Document US 11,443,569 B1 is also known. This document discloses a system for managing electric accumulators in an aircraft equipped with an electric thruster. It proposes monitoring an electric accumulator using a sensor reflecting the state of the battery. An alert is triggered when the measurement signal exceeds a predefined threshold.

[0011] The present invention therefore aims to propose a method for authorizing the flight of an aircraft equipped with a hybrid power plant aimed at guaranteeing before the flight that the aircraft can carry out the planned mission.

[0012] The invention relates to a method for authorizing the flight of an aircraft equipped with a hybrid power plant, said hybrid power plant having at least one thermal engine and at least one electric motor each capable of setting in motion a mechanical system, said electric motor being electrically connected to a source of electrical energy comprising a number of electrical accumulators greater than or equal to two.

[0013] This process involves the following steps: ground-based collection of electrical energy or electrical power to be collected from the electrical energy source for a predetermined duration, for example by operating an electrical load and / or the electric motor, determination for the electrical accumulators of initial values ​​of an operating parameter respectively within the electrical accumulators, calculation, with a controller for example, of an average value from the initial values, determination, with the controller for example, of a minimum value, said minimum value being equal to the lowest initial value among the initial values ​​measured, authorization of a flight of said aircraft when a difference between the average value and the minimum value is less than a threshold and prohibition of the flight of said aircraft when said difference between the average value and the minimum value is greater than or equal to the threshold, with an alerter for example.

[0014] For example, accumulators are configured to present identical values ​​for the same operating parameter.

[0015] When electrical energy or electrical power is taken from the electrical energy source, the electrical accumulators must, for example, present substantially identical electrical voltages at their terminals.

[0016] The ground sampling of electrical energy or electrical power to be taken from the electrical energy source for a predetermined duration can be carried out at constant electrical current or constant power, or in a frequency-dependent manner.

[0017] This process determines whether the difference between the average value and the minimum value is below a threshold. If so, no electric accumulator is defective. The electrical energy source powering the electric motor is therefore operational. The mission can then be carried out and the flight can be authorized. For example, a flight authorization signal is sent to an alerter and / or no flight ban signal is sent.

[0018] If not, flight is not authorized. In fact, the electric accumulator with the lowest value for the operating parameter is considered defective since the minimum value is far from the average value. In these conditions, a no-fly signal is sent to an alerter and / or no flight authorization signal is sent.

[0019] According to one example, the thermal engine can be used to set a rotor and / or a propeller in motion under normal conditions. The electric motor can be arranged in particular to be used to set the rotor and / or the propeller in motion in the event of a thermal engine failure. If the method makes it possible to detect before takeoff that the electrical energy source electrically supplying the electric motor is possibly faulty, the flight is prohibited for safety reasons. The method therefore makes it possible to guarantee that before takeoff the electric motor is in a condition to perform its function. The method therefore makes it possible to determine that the aircraft will be able to carry out the desired mission profile before takeoff, unlike systems that evolve a strategy in flight.

[0020] The method may comprise one or more of the following features, taken alone or in combination.

[0021] The ground collection of electrical energy or electrical power to be collected from the electrical energy source for a predetermined duration may, according to one example, comprise operation in motor mode of said electric motor.

[0022] The electric motor itself can be controlled to draw electrical energy or electrical power from the electrical energy source. This evaluates the actual operation of the electric motor. This feature can also allow testing of the electrical network connecting the electric motor to the electrical energy source, and the electric motor itself. If the electric motor does not operate according to a predetermined profile, theft is also prohibited.

[0023] In a complementary or alternative manner, said ground collection of electrical energy or electrical power to be taken from the electrical energy source for a predetermined duration may include operation of a predetermined electrical load electrically connected to the electrical energy source.

[0024] Eventually, an electrical load, different from the electric motor, dedicated or not dedicated to this function is under these conditions electrically powered by the electrical energy source.

[0025] The electrical energy or electrical power to be drawn during this step may be equal to a single stored value, or may result from the operation of the selected load. Alternatively, the electrical energy or electrical power to be drawn may be adjusted by controlling at least one electrical load, with the controller for example, depending on the value of at least one parameter, such as the mission to be carried out, a temperature in the electrical energy source, a state of health known as the English expression "State of Health", a state of charge or an age of the electrical energy source.

[0026] According to a possibility compatible with the previous ones, said average value is equal to the sum of the initial values ​​divided by said number of electric accumulators.

[0027] The average value then represents an arithmetic mean of the initial values.

[0028] According to a possibility compatible with the previous ones, the authorization of a flight of said aircraft may include the emission of a flight authorization signal when the difference between the average value and the minimum value is less than the threshold.

[0029] According to a possibility compatible with the previous ones, said flight ban may include the emission of a flight ban signal when said difference between the average value and the minimum value is greater than or equal to the threshold.

[0030] According to a first variant, the aircraft only transmits a flight authorization signal to an alerter when the difference between the average value and the minimum value is below the threshold. The alerter then emits an audible, visual and / or tactile alert following receipt of the flight authorization signal. Therefore, if no alert is issued, the pilot deduces that the flight is prohibited and that maintenance action must be taken.

[0031] According to a second variant, the aircraft only issues a no-fly signal when the said difference between the average value and the minimum value is greater than or equal to the threshold. The alerter then issues an audible, visual and / or tactile alert following receipt of the no-fly signal. Therefore, if no alert is issued, the pilot deduces that the flight is authorized.

[0032] According to a third variant, the aircraft transmits a flight authorization signal to an alerter when the difference between the average value and the minimum value is less than the threshold, the alerter generating a first audible, visual and / or tactile alert following receipt of the flight authorization signal. In addition, the aircraft transmits a no-fly signal when said difference between the average value and the minimum value is greater than or equal to the threshold, the alerter generating a second audible, visual and / or tactile alert different from the first alert following receipt of the no-fly signal. Depending on the alert transmitted, the pilot deduces whether the flight is authorized or prohibited.

[0033] According to a possibility compatible with the previous ones, the threshold can be determined during a preliminary phase by successively carrying out the following steps: drawing from the ground the electrical energy or the electrical power to be drawn from the electrical energy source for the predetermined duration, and determining for the electrical accumulators respective reference values ​​for said operating parameter rendering an electrical accumulator inoperative, drawing from the ground the electrical energy or the electrical power to be drawn from the electrical energy source for the predetermined duration in the presence of an electrical accumulator rendered inoperative, and determining at least for the operating electrical accumulator(s) respective test values, determining, for each electrical accumulator different from said electrical accumulator rendered inoperative, a difference between the corresponding reference value and test value, and determining said threshold as a function of said differences.

[0034] The expression "render an electric accumulator inoperative" means that the electric accumulator concerned no longer provides an electric current to an electric motor or an electric load as described above.

[0035] This process makes it possible to establish a threshold to be used by simulating the malfunction of an accumulator, for example by electrically disconnecting it from other electrical accumulators.

[0036] Optionally, the threshold may, for example, be equal to half of the largest deviation among the deviations.

[0037] The expression "the threshold may be equal to half of the largest difference" is to be interpreted with a margin, for example 10%, meaning "the threshold is equal to half of the largest difference plus or minus 10%".

[0038] This feature tends to avoid edge effects.

[0039] According to another characteristic, the threshold can be fixed, and for example determined according to the previous procedure.

[0040] Alternatively, the threshold can be variable.

[0041] For example, the method may include selecting a mission to be performed from a list of missions, the threshold being variable depending on the mission to be performed.

[0042] Each mission in the mission list can be associated with a respective threshold. The threshold value for each mission can be determined, for example, by following the previous procedure, with the electrical energy or electrical power to be drawn also varying depending on the mission.

[0043] Optionally, the threshold may be determined, for example by the controller, based on at least one parameter, such as a temperature in the electrical energy source, a state of health, a state of charge, or an age of the electrical energy source. The controller may be configured to calculate the threshold based on the mission to be performed configured with an interface, a temperature in the electrical energy source measured with a temperature sensor, a state of health of the electrical energy source evaluated with a standard monitoring sensor, a state of charge of the electrical energy source evaluated with a standard load sensor, or an age of the electrical energy source evaluated with a standard timer.

[0044] According to a first alternative, said operating parameter may be an electrical voltage, each electrical voltage being measured at terminals of the associated electrical accumulator, said determination for the electrical accumulators of respective initial values ​​of an operating parameter being carried out during said ground sampling of electrical energy or electrical power to be taken from the electrical energy source for a predetermined duration.

[0045] In fact, a used accumulator has a lower electrical voltage than a healthy accumulator. The electrical voltage can therefore represent the operating parameter monitored.

[0046] According to a second alternative, said determination for the electrical accumulators of respective initial values ​​of an operating parameter comprises for each electrical accumulator: measurement of a primary electrical voltage and a secondary electrical voltage at terminals of the associated electrical accumulator respectively before and after said drawing from the ground of electrical energy or electrical power to be drawn from the electrical energy source for a predetermined duration, said operating parameter being a difference between the primary electrical voltage and the secondary electrical voltage.

[0047] In fact, a used accumulator has a greater drop in electrical voltage than a healthy accumulator following a sample.

[0048] According to a third alternative, the determination for the electrical accumulators of respective initial values ​​of an operating parameter comprises for each electrical accumulator: measurement of a primary electrical voltage and a secondary electrical voltage at terminals of the associated electrical accumulator respectively before and after said ground sampling of electrical energy or electrical power to be taken from the electrical energy source for a predetermined duration, said operating parameter being an electrical capacity depending on a difference between the primary electrical voltage and the secondary electrical voltage.

[0049] The electrical capacity can be calculated in the usual way as a function of the primary electrical voltage and the secondary electrical voltage.

[0050] According to a fourth alternative, said determination for the electrical accumulators of respective initial values ​​of an operating parameter comprises for each electrical accumulator: measurement of a primary electrical voltage and a secondary electrical voltage at terminals of the associated electrical accumulator respectively before and after said drawing from the ground of electrical energy or electrical power to be drawn from the electrical energy source for a predetermined duration, said operating parameter is an electrical resistance depending on a difference between the primary electrical voltage and the secondary electrical voltage.

[0051] Electrical resistance can be calculated in the usual way as a function of the primary electrical voltage and the secondary electrical voltage.

[0052] According to a fifth alternative, said determination for the electrical accumulators of respective initial values ​​of an operating parameter comprising for each electrical accumulator: measurement of a temperature change within the electrical accumulator at least during said ground sampling of electrical energy or electrical power to be taken from the electrical energy source for a predetermined duration, said operating parameter being a function of said temperature change.

[0053] For example, the operating parameter is the slope coefficient of a curve described by the measured temperature. A used accumulator has a steeper slope than a healthy accumulator.

[0054] In addition to a method, the invention relates to a computer program comprising instructions which, when said program is executed by a system, lead said system to implement this method.

[0055] In addition to a method, the invention also relates to an aircraft configured to implement this method. The aircraft is equipped with a hybrid power plant, said hybrid power plant having at least one thermal engine and at least one electric motor each capable of setting in motion a mechanical system, said electric motor being electrically connected to a source of electrical energy comprising a number of electrical accumulators greater than or equal to two. The aircraft further comprises a flight authorization system configured to implement the method of the invention.

[0056] Optionally, the flight authorization system may comprise a sensor configured to at least participate in a measurement of the initial values ​​of an operating parameter respectively within the electrical accumulators, for example by measuring electrical voltages respectively at terminals of the electrical accumulators or temperatures within each electrical accumulator, a controller configured to require the ground sampling of electrical energy or electrical power to be taken from the electrical energy source for a predetermined duration as well as to calculate the average value and the minimum value and to determine whether a difference between the average value and the minimum value is less than a threshold or is greater than or equal to the threshold, and an alerter configured to generate at least one flight authorization or a flight ban.

[0057] The controller and / or sensor may be parts of the electrical power source.

[0058] The controller is then in communication with the sensor. The sensor emits one or more measurement signals carrying the initial values, or even the test values ​​and / or the reference values. The controller receives the measurement signal(s) to determine the minimum value and the average value, or even the aforementioned deviations. The controller then compares the difference between the average value and the minimum value with a threshold. As a result, the controller transmits a flight authorization or flight ban signal to the alerter.

[0059] The controller or another computer can receive the measurement signal(s) to determine the voltage deviations during a preliminary phase.

[0060] The invention and its advantages will appear in more detail in the context of the description which follows with examples given for illustrative purposes with reference to the appended figures which represent: there figure 1 , a diagram illustrating a mission of an aircraft according to the invention, the figure 2 , a diagram illustrating an aircraft according to the invention, the figure 3 , a diagram illustrating the method according to the invention, and the figure 4 , a diagram illustrating the determination of the threshold value.

[0061] Elements present in several distinct figures are assigned a single reference.

[0062] There figure 1 presents an aircraft 1 according to the invention. This aircraft 1 is equipped with a hybrid power plant 10. The hybrid power plant 10 comprises at least one thermal engine 15 and at least one electric motor 20 which are both capable of setting in motion a mechanical system 5, or even only a thermal engine 15 and an electric motor 20. The mechanical system 5 may have the function of participating in the advancement and / or propulsion of the aircraft 1.

[0063] For example, the thermal engine 15 is in operation by default, the electric motor 20 having the function of compensating for a breakdown of the thermal engine 15.

[0064] On a conventional aircraft, following a failure 96 of the thermal engine, the aircraft performs a descent 97. For example, a helicopter performs a so-called "autorotation" flight. When flying over an urban area 95, the aircraft is likely to head towards this area.

[0065] With an aircraft 1 according to the invention equipped with a hybrid power plant 10, following the breakdown 96 the electric motor 20 takes over from the thermal engine 15 and sets the mechanical system 5 in motion. For a certain duration, the aircraft 1 can continue its flight during an electrically powered flight phase 98, then perform a descent 99. For example, a helicopter performs a so-called “autorotation” flight. When flying over an urban area 95, the aircraft 1 is likely to move away from this urban area to reach a secure area 100.

[0066] An aircraft 1 according to the invention allows a pilot to ensure that the electric motor system is functional before takeoff.

[0067] There figure 2 schematically presents such an aircraft 1.

[0068] Thus, the aircraft 1 is equipped with a hybrid power plant 10. This hybrid power plant 10 comprises at least one thermal engine 15 configured to set in motion a mechanical system 5. The thermal engine 15 is further supplied with fuel by at least one tank not shown so as not to weigh down the figure 2 .

[0069] In addition, this hybrid power plant 10 comprises at least one electric motor 20 configured to set the mechanical system 5 in motion. The electric motor 20 may be a motor unit operating only in motor mode during which the electric motor provides mechanical power to the mechanical system 5, or may be an electric machine capable of operating as needed in a motor mode and an electric generator mode during which the electric motor generates electrical energy by being set in motion by the mechanical system 5.

[0070] For example, the mechanical system 5 comprises at least one rotor 6, at least one power transmission box 7, at least one freewheel 16, 21 and / or at least one mechanical connector. A heat engine 15 can be connected by a freewheel 16 to a power transmission box 7 setting at least one rotor 6 in motion. In addition, an electric motor 20 can be connected by a freewheel 21 to the power transmission box 7.

[0071] Furthermore, the electric motor 20 is electrically connected by a motor electrical network 80 to an electrical energy source 30. The motor electrical network 80 may comprise a connection / disconnection member 81 making it possible to electrically connect the electric motor 20 to the electrical energy source 30 on command. The connection / disconnection member 81 may take the form of a switch, a relay or the like.

[0072] The electrical energy source 30 comprises several electrical accumulators 31. The electrical accumulators 31 may be rechargeable. In particular, the electrical energy source 30 is provided with a number of electrical accumulators 31 greater than or equal to two. According to the example illustrated, the electrical energy source 30 is provided with three electrical accumulators 311, 312, 313.

[0073] The reference “31” is used to designate any electric accumulator, the references 311, 312 and 313 being used to designate, if necessary, a specific electric accumulator in order to explain the invention.

[0074] The electric accumulators 31 can be electrically connected in series and / or in parallel by wire connections, PCB (printed circuit board) type connections, solders, copper strips, etc.

[0075] The electric accumulators 31 can be grouped within one or more batteries.

[0076] Furthermore, the aircraft 1 comprises a flight authorization system 40 configured to determine at least whether the electrical energy source 30 is capable of delivering a predetermined electrical current and / or electrical power to the electric motor 20, so that the electric motor 20 can perform its function(s).

[0077] The flight authorization system 40 may comprise a sensor 50 configured to participate in the determination of the initial values ​​of an operating parameter respectively of the electric accumulators 31. Thus, for each electric accumulator 31, the sensor 50 is configured to emit one or more analog or digital signals carrying information relating to the initial value of an operating parameter within this electric accumulator 31.

[0078] Optionally, the sensor 50 may be part of an electric battery.

[0079] By sensor 50 is meant here a measuring system capable of measuring the required values. Similarly, the term "measurement" refers both to a raw measurement from a signal emitted by a sensor and to a measurement obtained by more or less complex signal processing from raw measurements.

[0080] According to one possibility, the operating parameter can be a function of an electrical voltage, each electrical voltage being measured at terminals 32, 33 of the associated electrical accumulator 31.

[0081] The references "32" and "33" are used to designate the two terminals of any electric accumulator 31, the references 321-331, 322-332, 323-333 being used to designate the terminals of specific electric accumulators 311, 312 and 313.

[0082] Thus, according to the illustrated example, the first electric accumulator 311 comprises a first terminal 321 and a second terminal 331, the second electric accumulator 312 comprises a first terminal 322 and a second terminal 332 and the third electric accumulator 313 comprises a first terminal 323 and a second terminal 333. Therefore, the sensor 50 measures an electrical voltage at terminals 321 and 331 of the first electric accumulator 311, another electrical voltage at terminals 322 and 332 of the second electric accumulator 312 and another electrical voltage at terminals 323 and 333 of the third electric accumulator 313.

[0083] Thus, the sensor 50 may comprise, for example, one sensor 51, 52, 53 per electric accumulator 311, 312, 313 to measure electrical voltages at terminals 321 and 331, 322 and 332, 323 and 333 of these electric accumulators 311, 312, 313. For example, each sensor 51, 52, 53 may take the form of a voltmeter.

[0084] According to another possibility, said operating parameter is a function of a temperature change within the electric accumulator 31. The sensor 50 can then comprise one temperature sensor per electric accumulator.

[0085] Furthermore, the flight authorization system 40 may comprise a controller 55 connected to the sensor 50 by wired or wireless communication, and where appropriate to each sensor 51, 52, 53.

[0086] The controller 55 may be provided with one or more processing units comprising, 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 not limiting the scope given to the expression “processing unit”. The term processor may also designate a central processing unit known by the acronym CPU, a graphics processing unit GPU, a digital unit known by the acronym DSP, a microcontroller, etc. Optionally, one or more processing units of the controller 55 may be parts of an electric battery or may be remote or may also perform other functions. One or more processing units of the controller 55 may or may not be dedicated to the invention.

[0087] The controller 55 can further be connected to a human-machine control interface 70 by a wired and / or wireless connection, directly or indirectly via other components and for example an avionics computer. This human-machine control interface 70 can transmit an analog or digital signal to the controller 55 to implement the method of the invention.

[0088] Furthermore, the flight authorization system 40 may comprise an alerter 60. The alerter 60 may be connected to the controller 55 by wired or wireless communication. The controller 55 is configured to transmit one or more analog or digital alert signals to the alerter 60. The alerter 60 is configured to generate at least one visual, audible and / or tactile flight authorization or flight ban.

[0089] For example, the alerter 60 may include a light-emitting diode 61 illuminated when a flight authorization is granted by the controller 55, and / or another light-emitting diode 62 illuminated when a flight ban is issued by the controller 55.

[0090] For example, the alerter 60 may comprise a vibrating unit 64 vibrating an organ held or worn by an individual, the vibrating unit 64 being able to generate in said organ a first vibration when a flight authorization is granted by the controller 55, and / or a second vibration when a flight ban is issued by the controller 55. Where appropriate, the first vibration and the second vibration may be different.

[0091] For example, the alerter 60 may include a loudspeaker 65 capable of emitting a first sound when a flight authorization is granted by the controller 55, and / or a second sound when a flight ban is issued by the controller 55. Where appropriate, the first sound and the second sound may be different.

[0092] According to another aspect, the flight authorization system 40 may comprise an electrical load 75 electrically connected by an electrical sampling network 76 to the electrical energy source 30. The electrical sampling network 76 may comprise a connection / disconnection means 77 making it possible to electrically connect the electrical load 75 to the electrical energy source 30 on command. The connection / disconnection means 77 may take the form of a switch, a relay or the like.

[0093] If necessary, the controller 55 can be connected by a wired or wireless connection to the connection / disconnection member 81 and / or to the connection / disconnection means 77 previously described.

[0094] There figure 3 illustrates the method of the invention. This method can be implemented by a computer program comprising instructions. When said program is executed by the system 40, the executed instructions cause the system 40 to implement this method.

[0095] The method comprises a monitoring phase Phas, carried out prior to takeoff, for example when starting the aircraft 1. Optionally, the monitoring phase can be initiated when the human-machine control interface 70 is operated. For example, the human-machine control interface 70 directly transmits a control signal to the controller 55, or transmits a signal to a third-party device which in turn directly or indirectly transmits a control signal to the controller 55.

[0096] During the monitoring phase Phas, the method comprises a ground sampling STP1 of electrical energy or electrical power to be taken from the electrical energy source 30 for a predetermined duration.

[0097] For example, this step involves the operation STP1.1 in motor mode of the electric motor 20.

[0098] Optionally, the controller 55 can control the motor electrical network 80 so that an electric current flows between the electric motor 20 and the electrical energy source 30. For example, the controller 55 controls the connection / disconnection member 81.

[0099] In a complementary or alternative manner, the controller 55 can control the electrical sampling network 76 so that an electric current flows between the electrical load 75 and the electrical energy source 30. For example, the controller 55 controls the connection / disconnection means 76.

[0100] Optionally, the predetermined duration may be fixed or calculated, for example by the controller 55. According to one illustration, the controller 55 is configured to calculate the predetermined duration based on an outside temperature measured with a temperature sensor.

[0101] Therefore, before and / or during and / or after this withdrawal of electrical energy or electrical power, the monitoring phase Phas includes the determination STP2 for the electrical accumulators 31 of respective initial values ​​Vmes for an operating parameter.

[0102] Therefore, the monitoring phase Phas includes a calculation STP3 with the controller 55 of an average value Vmoy from the initial values ​​Vmes.

[0103] According to a first alternative feasible with the system of the figure 2 , the sensor 55 measures an initial electrical voltage Vmes1 at terminals 321 and 331 of the first accumulator 311, a second initial electrical voltage Vmes2 at terminals 322 and 332 of the second accumulator 312 and a third initial electrical voltage Vmes3 at terminals 323 and 333 of the third accumulator 313.

[0104] For each electric accumulator 30, the initial value Vmes can be the electric voltage measured in real time and at a predetermined instant, or can be equal to an average of the electric voltages measured during said predetermined duration.

[0105] The initial electrical voltages Vmes can be stored in a memory of the controller 55 or in another memory.

[0106] Therefore, the monitoring phase Phas includes a calculation STP3 with the controller 55 of an average value Vmoy from the initial electrical voltages Vmes.

[0107] The average value Vmoy is for example equal to the sum of the initial electrical voltages Vmes divided by the said number Nbr. According to the example of the figure 2 , the average value Vmoy is for example equal to the sum of the first electrical voltage Vmes1 and the second electrical voltage Vmes2 and the third electrical voltage Vmes3 divided by 3, i.e. Vmoy = (Vmes1+Vmes2+Vmes3) / 3.

[0108] According to a second alternative feasible with the system of the figure 2 , the sensor 50 measures for each electric accumulator 31 a primary electric voltage and a secondary electric voltage respectively before and after said ground sampling of an electric energy or an electric power to be sampled from the electric energy source 30 for a predetermined duration. For each electric accumulator 31, the controller 55 calculates the associated initial value Vmes, this initial value Vmes being equal to a difference between the primary electric voltage and the secondary electric voltage.

[0109] The average value Vmoy is for example equal to the sum of the initial values ​​Vmes divided by the said number Nbr.

[0110] According to a third alternative feasible with the system of the figure 2 , the sensor 50 measures for each electric accumulator 31 a primary electric voltage and a secondary electric voltage respectively before and after said drawing from the ground of an electric energy or an electric power to be drawn from the electric energy source 30 for a predetermined duration. For each electric accumulator 31, the controller 55 calculates the associated initial value Vmes, this initial value Vmes being an electric capacity depending on a difference between the primary electric voltage and the secondary electric voltage.

[0111] The average value Vmoy is for example equal to the sum of the initial values ​​Vmes divided by the said number Nbr.

[0112] According to a fourth alternative feasible with the system of the figure 2 , the sensor 50 measures for each electric accumulator 31 a primary electric voltage and a secondary electric voltage respectively before and after said drawing from the ground of an electric energy or an electric power to be drawn from the electric energy source 30 for a predetermined duration. For each electric accumulator 31, the controller 55 calculates the associated initial value Vmes, this initial value Vmes being an electric resistance depending on a difference between the primary electric voltage and the secondary electric voltage.

[0113] The average value Vmoy is for example equal to the sum of the initial values ​​Vmes divided by the said number Nbr.

[0114] According to a fifth alternative, the sensor 50 measures for each electric accumulator 31 a temperature within this electric accumulator 31 at least during, or even before and / or after said ground sampling of electrical energy or electrical power to be sampled from the electrical energy source 30 for a predetermined duration. For each electric accumulator 31, the controller 55 calculates the associated initial value Vmes, this initial value Vmes being a function of said temperature change. For example, the operating parameter is the slope coefficient of a curve described by the measured temperature.

[0115] The average value Vmoy is for example equal to the sum of the initial values ​​Vmes divided by the said number Nbr.

[0116] Regardless of the way of evaluating the initial values ​​Vmes as well as the average value Vmoy and with reference to the figure 3 , the monitoring phase Phas also includes the determination STP4 of a minimum value Vmin. The controller 55 can determine the minimum value Vmin, this minimum value Vmin being equal to the lowest initial value Vmes among the initial values ​​Vmes measured.

[0117] From then on, the controller 55 transmits a signal to the alerter 60 in order to generate a flight authorization for the aircraft 1 when a difference Diff between the average value Vmoy and the minimum value Vmin is less than a predetermined threshold S, and a flight ban for the aircraft 1 when said difference Diff is greater than or equal to the threshold S.

[0118] For illustration purposes, according to the example of the first alternative and the example of the figure 2 the first electrical voltage is equal to 2.7 Volts, the second electrical voltage is equal to 3.5 Volts and the third electrical voltage is equal to 3.4 Volts. The average electrical voltage Vmoy is then equal to 3.2 Volts and the minimum electrical voltage Vmin is equal to the first electrical voltage, i.e. 2.7 Volts.

[0119] If the threshold is set at 0.3 Volts, then the difference between the average electrical voltage Vmoy and the minimum electrical voltage Vmin is 0.5 Volts and is greater than the threshold S. Flight is then prohibited. A maintenance action can then be triggered.

[0120] If the threshold is set at 0.6 Volts, then the difference between the average electrical voltage Vmoy and the minimum electrical voltage Vmin is less than the threshold. Flight is then authorized.

[0121] To authorize the flight, the controller 55 can emit a flight authorization signal when the difference between the value Vmoy and the minimum value Vmin is less than the threshold S. Upon receipt of the flight authorization signal, the alerter 60 can then either generate no alert in the case where the alerter 60 only emits an alert in the event of a ban, or generate an alert carrying the flight authorization.

[0122] To prohibit the flight, the controller 55 can emit a no-flight signal when the difference between the average value Vmoy and the minimum value Vmin is greater than or equal to the threshold S. Upon receipt of the no-flight signal, the alerter 60 can then either generate no alert in the case where the alerter 60 only emits an alert in the case of flight authorization, or generate an alert carrying the no-flight warning.

[0123] According to another aspect, the threshold may be fixed or may vary depending on the situation encountered. For example, a pilot may request a mission human-machine interface to select a mission to be carried out from a predetermined list of missions, the controller 55 being able to determine the value of the threshold S using a list storing for each mission a said value of the threshold S.

[0124] According to one possibility, the controller 55 can calculate the threshold based on a temperature in the electrical energy source measured with a temperature sensor, a health state of the electrical energy source evaluated with a usual monitoring sensor, a state of charge of the electrical energy source evaluated with a usual load sensor, and / or an age of the electrical energy source evaluated with a usual timer.

[0125] The value of the threshold S or a law allowing this value to be calculated as a function of one or more parameters can be established by tests or simulations for example.

[0126] To evaluate the value of the threshold S, for example for a particular mission or for certain values ​​of certain parameters, the method may possibly comprise a preliminary phase STP0. This preliminary phase STP0 may comprise a sampling STP0.1 on the ground of the electrical energy or the electrical power to be sampled mentioned above from the electrical energy source 30 for the predetermined duration mentioned above. For example, this step STP0.1 comprises the operation in motor mode of the electric motor 20 or the electrical supply of an electrical load 75 like the step STP1 previously described.

[0127] The preliminary phase STP0 comprises the measurement STP0.2, with the sensor 50 for the electric accumulators 31 of respective reference values ​​Vref, each reference electric voltage Vref according to the first alternative being measured at the terminals 32, 33 of the associated electric accumulator 31.

[0128] The reference values ​​Vref are stored for further processing, for example in a memory of the controller 55 or another processing unit.

[0129] The preliminary phase STP0 comprises a step STPO.3 consisting of rendering inoperative an electric accumulator 31, for example the electric accumulator 311 of the figure 2 , to evaluate the threshold value. For example, an operator modifies the wiring of the electrical energy source 30 to disconnect the electrical accumulator 311 concerned, or the controller 55 acts on one or more switches or an equivalent to achieve the same effect.

[0130] Therefore, the preliminary phase STP0 comprises a sampling STPO.4 on the ground of the electrical energy or the electrical power to be taken from the electrical energy source 30 for the predetermined duration in the presence of an electrical accumulator 31 rendered inoperative, namely the first electrical accumulator 311 according to the example given, and a measurement STP0.5 for the electrical accumulators 31 of respective test values ​​Vtest.

[0131] The reference steps STP0.1 and STP0.2 are in fact reproduced with an inoperative electric accumulator 31 to simulate a malfunction of the electrical energy source 30.

[0132] From then on, a processing unit and for example the controller 55 determines, for each electric accumulator 31 different from the electric accumulator rendered inoperative, a difference between the reference value Vref and the corresponding test value Vtest.

[0133] There figure 4 illustrates the variation of the reference electrical voltage Vref and the test electrical voltage Vtest over time in the context of the first alternative. This figure 4 presents the time on the abscissa, and an electrical voltage on the ordinate. Curve C1 represents the reference electrical voltage Vref and curve C2 represents the test electrical voltage Vtest.

[0134] It can be seen that at each instant an ECT gap separates curve C1 and curve C2. Indeed, in the event of failure of an electric accumulator 31, the electrical energy or electrical power taken from the other electric accumulators 31 is greater than in the absence of faulty electric accumulators 31.

[0135] Therefore, the method comprises the determination of said threshold S as a function of said voltage differences, for example using a processing unit or even the controller 55.

[0136] Optionally, the threshold S may be equal to half of the largest voltage difference among the voltage differences recorded.

[0137] Naturally, the present invention is subject to numerous variations in its implementation, while remaining within the scope of the claims. Although several embodiments have been described, it is understood that it is not conceivable to exhaustively identify all possible modes.

Claims

1. Method for authorising the flight of an aircraft (1) provided with a hybrid power plant (10), said hybrid power plant (10) having at least one heat engine (15) and at least one electric motor (20) each capable of moving a mechanical system (5), said electric motor (20) being electrically connected to an electric energy source (30) comprising a number (Nbr) of electric accumulators (31) that is greater than or equal to two, the method comprising the following steps of: - ground-based drawing (STP1) of electric energy or electric power that is to be drawn from the electric energy source (30) for a predetermined duration; - determining (STP2), for the electric accumulators (31), initial values (Vmes) of an operating parameter, respectively within the electric accumulators (31); - computing (STP3) an average value (Vav) based on the initial values (Vmes); - determining (STP4) a minimum value (Vmin), with said minimum value (Vmin) being equal to the lowest initial value (Vmes) from among the measured initial values (Vmes); - authorising a flight of said aircraft (1) when a difference between the average value (Vav) and the minimum value (Vmin) is below a threshold (S) and prohibiting the flight of said aircraft (1) when said difference between the average value (Vav) and the minimum value (Vmin) is greater than or equal to the threshold (S).

2. Method according to claim 1, wherein said step (STP1) of ground-based drawing of electric energy or electric power that is to be drawn from the electric energy source (30) for a predetermined duration comprises operating (STP1.1) in the motor mode of said electric motor (20).

3. Method according to any one of claims 1 to 2, wherein said step (STP1) of ground-based drawing of electric energy or electric power that is to be drawn from the electric energy source for a predetermined duration comprises operating (STP1. 2) a predetermined electric load (75) electrically connected to the electric energy source (30).

4. Method according to any one of claims 1 to 3, wherein said average value (Vav) is equal to the sum of the initial values (Vmes) divided by said number (Nbr).

5. Method according to any one of claims 1 to 4, wherein said authorization of a flight of said aircraft (1) comprises transmitting a flight authorisation signal when the difference between the average value (Vav) and the minimum value (Vmin) is below the threshold (S).

6. Method according to any one of claims 1 to 5, wherein said prohibition of the flight comprises transmitting a flight prohibition signal when said difference between the average value (Vav) and the minimum value (Vmin) is greater than or equal to the threshold (S).

7. Method according to any one of claims 1 to 6, wherein said threshold (S) is determined during a preliminary phase (STP0) by successively carrying out the following steps of: - ground-based drawing (STP0.1) of electric energy or electric power that is to be drawn from the electric energy source (30) for a predetermined duration, and determining, for the electric accumulators (31), respective reference values (Vref) for said operating parameter; - rendering an electric accumulator (311) inoperative; - ground-based drawing of electric energy or electric power that is to be drawn from the electric energy source (30) for the predetermined duration in the presence of an electric accumulator (311) that has been rendered inoperative, and determining, at least for the one or more operative electric accumulators, respective test values (Vtest) for said operating parameter; - determining, for each electric accumulator (31) other than said electric accumulator that has been rendered inoperative, a deviation between the reference value (Vref) and the corresponding test value (Vtest); - determining said threshold (S) as a function of said deviations.

8. Method according to claim 7, wherein said threshold (S) is equal to half the largest deviation from among the deviations.

9. Method according to any one of claims 1 to 8, wherein said threshold (S) is fixed or variable.

10. Method according to any one of claims 1 to 9, wherein said operating parameter is an electric voltage, with each electric voltage being measured at terminals of the associated electric accumulator (31), with said determining (STP2), for the electric accumulators (31), of respective initial values (Vmes) of an operating parameter being carried out while implementing the step (STP1) of ground-based drawing of electric energy or electric power that is to be drawn from the electric energy source (30) for a predetermined duration.

11. Method according to any one of claims 1 to 9, wherein said determining (STP2), for the electric accumulators (31), of respective initial values (Vmes) of an operating parameter comprises, for each electric accumulator: measuring a primary electric voltage and a secondary electric voltage at terminals of the associated electric accumulator (31), respectively before and after said step (STP1) of ground-based drawing of electric energy or electric power that is to be drawn from the electric energy source (30) for a predetermined duration, with said operating parameter being a difference between the primary electric voltage and the secondary electric voltage.

12. Method according to any one of claims 1 to 9, wherein said determining (STP2), for the electric accumulators (31), of respective initial values (Vmes) of an operating parameter comprises, for each electric accumulator: measuring a primary electric voltage and a secondary electric voltage at terminals of the associated electric accumulator (31), respectively before and after said step (STP1) of ground-based drawing of electric energy or electric power that is to be drawn from the electric energy source (30) for a predetermined duration, with said operating parameter being an electric capacitance dependent on a difference between the primary electric voltage and the secondary voltage electric power.

13. Method according to any one of claims 1 to 9, wherein said determining (STP2), for the electric accumulators (31), of respective initial values (Vmes) of an operating parameter comprises, for each accumulator: measuring a primary electric voltage and a secondary electric voltage, respectively at terminals of the associated electric accumulator (31) before and after said step (STP1) of ground-based drawing of electric energy or electric power that is to be drawn from the electric energy source (30) for a predetermined duration, with said operating parameter being an electric resistance dependent on a difference between the primary electric voltage and the secondary electric voltage.

14. Method according to any one of claims 1 to 9, wherein said determining (STP2), for the electric accumulators (31), of respective initial values (Vmes) of an operating parameter comprises, for each accumulator: measuring a change in temperature within the electric accumulator at least during said step (STP1) of ground-based drawing of electric energy or electric power that is to be drawn from the electric energy source (30) for a predetermined duration, with said operating parameter being dependent on said change in temperature.

15. Computer program comprising instructions which, when said program is executed by a system (40), cause said system (40) to implement the method according to any one of claims 1 to 14.

16. Aircraft (1) provided with a hybrid power plant (10), said hybrid power plant (10) having at least one heat engine (15) and at least one electric motor (20) each capable of moving a mechanical system (5), said electric motor (20) being electrically connected to an electric energy source (30) comprising a number of electric accumulators (31) that is greater than or equal to two, said aircraft (1) comprising a flight authorisation system (40) configured to implement the method according to any one of claims 1 to 14.

17. Aircraft according to claim 16, the flight authorisation system (40) comprising a sensor (50) configured to at least assist in a measurement of the initial values of an operating parameter, respectively within the terminals of the electric accumulators (31), a controller (55) configured to request ground-based drawing of electric energy or electric power that is to be drawn from the electric energy source (30) for a predetermined duration, as well as to compute the average value (Vav) and the minimum value (Vmin) and to determine whether a difference between the average value (Vav) and the minimum value (Vmin) is below a threshold (S), and an indicator (60) configured to generate at least one flight authorisation or flight prohibition.