METHOD FOR AUTHORIZING THE FLIGHT OF AN AIRCRAFT HAVING A HYBRID POWER PLANT PROVIDED WITH AT LEAST ONE ELECTRIC MOTOR AND AT LEAST ONE HEAT ENGINE

Abstract

A method for authorizing the flight of an aircraft provided with a hybrid power plant having at least one heat engine and at least one electric motor electrically connected to an electrical energy source comprising several electrical accumulators. The method comprises extracting (STP1), while on the ground, an electrical energy or an electrical power to be extracted from the electrical energy source during a predetermined time period and determining (STP2) for the electrical accumulators, respective initial values of an operating parameter, calculating (STP3) an average value from the initial values, determining (STP4) a minimum value from the measured initial values, issuing an authorization when a difference between the average value and the minimum value is less than a threshold and a prohibition when said difference between the average value and the minimum value is greater than or equal to the threshold.

Claims

1. A method for authorizing the flight of an aircraft provided with a hybrid power plant, the hybrid power plant having at least one heat engine and at least one electric motor that are each able to set a mechanical system in motion, the electric motor being electrically connected to an electrical energy source comprising a number (Nbr) of electrical accumulators greater than or equal to two, wherein the method comprises the following steps: extracting (STP1), while on the ground, an electrical energy or an electrical power to be extracted from the electrical energy source during a predetermined time period; determining (STP2), for the electrical accumulators, initial values (Vmes) of an operating parameter of the respective electrical accumulators; calculating (STP3) an average value (Vmoy) from the initial values (Vmes); determining (STP4) a minimum value (Vmin), the minimum value (Vmin) being equal to the lowest of the measured initial values (Vmes); and authorizing the aircraft to fly when a difference between the average value (Vmoy) and the minimum value (Vmin) is less than a threshold (S) and prohibiting the aircraft (1) from flying when the difference between the average value (Vmoy) and the minimum value (Vmin) is greater than or equal to the threshold (S).

2. The method according to claim 1, wherein extracting (STP1), while on the ground, of an electrical energy or an electrical power to be extracted from the electrical energy source during a predetermined time period comprises operating (STP1.1) the electric motor in motor mode.

3. The method according to claim 1, wherein extracting (STP1), while on the ground, of an electrical energy or an electrical power to be extracted from the electrical energy source during a predetermined time period comprises operating (STP1.2) a predetermined electrical load electrically connected to the electrical energy source.

4. The method according to claim 1, wherein the average value (Vmoy) is equal to the sum of the initial values (Vmes) divided by the number (Nbr).

5. The method according to claim 1, wherein authorizing of a flight of the aircraft comprises transmitting a flight authorization signal when the difference between the average value (Vmoy) and the minimum value (Vmin) is less than the threshold (S).

6. The method according to claim 1, wherein prohibiting the aircraft from flying comprises transmitting a flight prohibition signal when the difference between the average value (Vmoy) and the minimum value (Vmin) is greater than or equal to the threshold (S).

7. The method according to claim 1, wherein the threshold (S) is determined during a preliminary phase (STP0) by carrying out the following steps in succession: extracting (STP0.1), while on the ground, electrical energy or electrical power to be extracted from the electrical energy source during the predetermined time period, and determining, for the electrical accumulators, respective reference values (Vref) for the operating parameter; rendering an electrical accumulator inoperative; extracting, while on the ground, electrical energy or electrical power to be extracted from the electrical energy source during the predetermined time period in the presence of an electrical accumulator that has been rendered inoperative, and determining respective test values (Vtest) for the operating parameter, at least for the operative electrical accumulator or accumulators; determining, for each electrical accumulator different from the electrical accumulator that has been rendered inoperative, a deviation between the reference value (Vref) and the corresponding test value (Vtest); and determining the threshold (S) as a function of the deviations.

8. The method according to claim 7, wherein the threshold (S) is equal to half of the greatest deviation among the deviation.

9. The method according to claim 1, wherein the threshold (S) is fixed or variable.

10. The method according to claim 1, wherein the operating parameter is an electrical voltage, each electrical voltage being measured at terminals of the associated electrical accumulator, determining (STP2), for the electrical accumulators, of respective initial values (Vmes) of an operating parameter being carried out during extracting (STP1), while on the ground, of an electrical energy or an electrical power to be extracted from the electrical energy source during a predetermined time period.

11. The method according to claim 1, wherein determining (STP2), for the electrical accumulators, of respective initial values (Vmes) of an operating parameter comprises, for each electrical accumulator: measuring a primary electrical voltage and a secondary electrical voltage at terminals of the associated electrical accumulator respectively before and after extracting (STP1), while on the ground, of an electrical energy or an electrical power to be extracted from the electrical energy source during a predetermined time period, the operating parameter being a difference between the primary electrical voltage and the secondary electrical voltage.

12. The method according to claim 1, wherein determining (STP2), for the electrical accumulators, of respective initial values (Vmes) of an operating parameter comprises, for each electrical accumulator: measuring a primary electrical voltage and a secondary electrical voltage at terminals of the associated electrical accumulator respectively before and after extracting (STP1), while on the ground, of an electrical energy or an electrical power to be extracted from the electrical energy source during a predetermined time period, the operating parameter being an electrical capacitance that is a function of a difference between the primary electrical voltage and the secondary electrical voltage.

13. The method according to claim 1, wherein determining (STP2), for the electrical accumulators, of respective initial values (Vmes) of an operating parameter comprises, for each electrical accumulator: measuring a primary electrical voltage and a secondary electrical voltage respectively at terminals of the associated electrical accumulator before and after extracting (STP1), while on the ground, of an electrical energy or an electrical power to be extracted from the electrical energy source during a predetermined time period, the operating parameter being an electrical resistance that is a function of a difference between the primary electrical voltage and the secondary electrical voltage.

14. The method according to claim 1, wherein determining (STP2), for the electrical accumulators, of respective initial values (Vmes) of an operating parameter comprises, for each electrical accumulator: measuring a change in temperature inside the electrical accumulator at least during extracting (STP1), while on the ground, of an electrical energy or an electrical power to be extracted from the electrical energy source during a predetermined time period, the operating parameter being a function of the change in temperature.

15. A computer program comprising instructions that, when the program is run by a system, cause the system to implement the method according to claim 1.

16. An aircraft provided with a hybrid power plant, the hybrid power plant having at least one heat engine and at least one electric motor that are each able to set a mechanical system in motion, the electric motor being electrically connected to an electrical energy source comprising a number of electrical accumulators greater than or equal to two, wherein the aircraft comprises a flight authorization system configured to implement the method according to claim 1.

17. The aircraft according to claim 16, wherein the flight authorization system comprises a sensor configured to at least participate in a measurement of the initial values of an operating parameter within the respective terminals of the electrical accumulators, a controller configured to request extracting, while on the ground, of an electrical energy or an electrical power to be extracted from the electrical energy source during a predetermined time period and to calculate the average value (Vmoy) and the minimum value (Vmin) and to determine whether a difference between the average value (Vmoy) and the minimum value (Vmin) is less than a threshold (S), and an alerter configured to generate at least a flight authorization or a flight prohibition.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The disclosure and its advantages appear in greater detail in the context of the following description of embodiments given by way of illustration and with reference to the accompanying figures, wherein:

[0070] FIG. 1 is a diagram showing a mission of an aircraft according to the disclosure;

[0071] FIG. 2 is a diagram showing an aircraft according to the disclosure;

[0072] FIG. 3 is a diagram showing the method according to the disclosure; and

[0073] FIG. 4 is a diagram showing the determination of the value of the threshold.

DETAILED DESCRIPTION

[0074] Elements that are present in more than one of the figures are given the same references in each of them.

[0075] FIG. 1 shows an aircraft 1 according to the disclosure. This aircraft 1 is provided with a hybrid power plant 10. The hybrid power plant 10 comprises at least one heat engine 15 and at least one electric motor 20 that are both able to set a mechanical system 5 in motion, or indeed only a heat engine 15 and an electric motor 20. The purpose of the mechanical system 5 may be to contribute to the movement and/or the propulsion of the aircraft 1.

[0076] For example, the heat engine 15 operates by default, the electric motor 20 having the function of compensating for a failure of the heat engine 15.

[0077] On a conventional aircraft, following a failure 96 of the heat engine, the aircraft descends 97. For example, a helicopter performs autorotation flight. When flying over an urban area 95, the aircraft is likely to move towards this area.

[0078] With an aircraft 1 according to the disclosure provided with a hybrid power plant 10, following the failure 96, the electric motor 20 takes over from the heat engine 15 and sets the mechanical system 5 in motion. For a certain period of time, the aircraft 1 can continue its flight during an electrically powered flight phase 98, and then descends 99. For example, a helicopter performs autorotation flight. When flying over an urban area 95, the aircraft is likely to move away from this urban area in order to reach a secured area 100.

[0079] An aircraft 1 according to the disclosure allows a pilot to ensure that the electric motor system is operational prior to take-off.

[0080] FIG. 2 shows such an aircraft 1 schematically.

[0081] The aircraft 1 is thus provided with a hybrid power plant 10. This hybrid power plant 10 comprises at least one heat engine 15 configured to set a mechanical system 5 in motion. The heat engine 15 is also supplied with fuel by at least one tank that is not shown so as not to clutter FIG. 2.

[0082] Moreover, 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 drive member that operates only in a motor mode wherein the electric motor provides mechanical power to the mechanical system 5, or may be an electric machine capable of operating, as required, in a motor mode and an electric generator mode wherein the electric motor generates electrical energy by being set in motion by the mechanical system 5.

[0083] For example, the mechanical system 5 comprises at least one rotor 6, at least one gearbox 7, at least one free-wheel 16, 21 and/or at least one mechanical connector. A heat engine 15 may be connected via a free-wheel 16 to a gearbox 7 setting at least one rotor 6 in motion. Moreover, an electric motor 20 may be connected via a free-wheel 21 to the gearbox 7.

[0084] Moreover, the electric motor 20 is electrically connected by a motor electricity network 80 to an electrical energy source 30. The motor electricity network 80 may comprise a connection/disconnection member 81 allowing the electric motor 20 to be electrically connected to the electrical energy source 30 on command. The connection/disconnection member 81 may be in the form of a switch, a relay or the like.

[0085] 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 shown, the electrical energy source 30 is provided with three electrical accumulators 311, 312, 313.

[0086] Reference number 31 is used to denote any electrical accumulator, reference numbers 311, 312 and 313 being used as required to denote a specific electrical accumulator in order to explain the disclosure.

[0087] The electrical accumulators 31 may be electrically connected in series and/or in parallel by wired links, PCB (printed circuit board) links, welds, copper strips, etc.

[0088] The electrical accumulators 31 may be grouped together within one or several batteries.

[0089] Moreover, the aircraft 1 comprises a flight authorization system 40 configured to determine, at a minimum, whether the electrical energy source 30 is able to deliver a predetermined electric current and/or electrical power to the electric motor 20, in order for the electric motor 20 to be able to perform its function or functions.

[0090] The flight authorization system 40 may comprise a sensor 50 configured to participate in the determination of the initial values of an operating parameter of the respective electrical accumulators 31. Thus, for each electrical accumulator 31, the sensor 50 is configured to transmit one or more analog or digital signals carrying information relating to the initial value of an operating parameter within this electrical accumulator 31.

[0091] The sensor 50 may possibly be a part of an electric battery.

[0092] Sensor 50 should be understood to mean a measurement system capable of measuring the required values. Similarly, the expression measurement refers to both a raw measurement from a signal transmitted by a sensing device and a measurement obtained by relatively complex processing of raw measurement signals.

[0093] According to one possibility, the operating parameter may be a function of an electrical voltage, each electrical voltage being measured at terminals 32, 33 of the associated electrical accumulator 31.

[0094] Reference numbers 32 and 33 are used to denote the two terminals of any electrical accumulator 31, reference numbers 321-331, 322-332, 323-333 being used to denote the terminals of specific electrical accumulators 311, 312 and 313.

[0095] Thus, according to the example shown, the first electrical accumulator 311 comprises a first terminal 321 and a second terminal 331, the second electrical accumulator 312 comprises a first terminal 322 and a second terminal 332 and the third electrical accumulator 313 comprises a first terminal 323 and a second terminal 333. Therefore, the sensor 50 measures one electrical voltage at the terminals 321 and 331 of the first electrical accumulator 311, another electrical voltage at the terminals 322 and 332 of the second electrical accumulator 312 and another electrical voltage at the terminals 323 and 333 of the third electrical accumulator 313.

[0096] Thus, the sensor 50 may comprise, for example, one sensing device 51, 52, 53 for each electrical accumulator 311, 312, 313 for measuring electrical voltages at the terminals 321 and 331, 322 and 332, 323 and 333 of these electrical accumulators 311, 312, 313. For example, each sensing device 51, 52, 53 may be in the form of a voltmeter.

[0097] According to another possibility, said operating parameter is a function of a change in temperature within the electrical accumulator 31. The sensor 50 may then comprise one temperature sensor for each electrical accumulator.

[0098] Moreover, the flight authorization system 40 may comprise a controller 55 connected to the sensor 50 by a wired or wireless communication means and, if required, to each sensing device 51, 52, 53.

[0099] 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 refer equally to a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), a microcontroller, etc. One or more processing units of the controller 55 may optionally be parts of an electric battery or may be located separately and may even perform other functions. One or more processing units of the controller 55 may be dedicated or not dedicated to the disclosure.

[0100] The controller 55 may also be connected to a human-machine control interface 70 by a wired and/or wireless link, directly or indirectly via other members 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 disclosure.

[0101] Moreover, the flight authorization system 40 may comprise an alerter 60. The alerter 60 may be connected to the controller 55 by a wired or wireless communication means. 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, audio and/or tactile flight authorization or flight prohibition.

[0102] For example, the alerter 60 may comprise one light-emitting diode 61 that is illuminated when a flight authorization is granted by the controller 55, and/or another light-emitting diode 62 that is illuminated when a flight prohibition is transmitted by the controller 55.

[0103] For example, the alerter 60 may comprise a vibrating unit 64 that makes a member held or worn by an individual vibrate, the vibrating unit 64 being able to generate a first vibration in said member when a flight authorization is granted by the controller 55, and/or a second vibration when a flight prohibition is transmitted by the controller 55. If applicable, the first vibration and the second vibration may be different.

[0104] For example, the alerter 60 may comprise a loudspeaker 65 that can transmit a first sound when a flight authorization is granted by the controller 55, and/or a second sound when a flight prohibition is transmitted by the controller 55. If applicable, the first sound and the second sound may be different.

[0105] According to another aspect, the flight authorization system 40 may comprise an electrical load 75 electrically connected by an electricity supply network 76 to the electrical energy source 30. The electricity supply network 76 may comprise a connection/disconnection means 77 for electrically connecting the electrical load 75 to the electrical energy source 30 on command. The connection/disconnection means 77 may be in the form of a switch, a relay or the like.

[0106] If applicable, the controller 55 may be connected by a wired or wireless link to the connection/disconnection member 81 and/or the connection/disconnection means 77 described above.

[0107] FIG. 3 shows the method of the disclosure. This method may be implemented by a computer program comprising instructions. When said program is run by the system 40, the instructions that are run cause the system 40 to implement this method.

[0108] The method comprises a monitoring phase Phas, carried out prior to take-off, for example when the aircraft 1 is started up. The monitoring phase may possibly be launched when the human-machine control interface 70 is operated. For example, the human-machine control interface 70 transmits a command signal directly to the controller 55, or transmits a signal to a separate component that in turn transmits a command signal directly or indirectly to the controller 55.

[0109] During the monitoring phase Phas, the method comprises extracting STP1, while on the ground, an electrical energy or an electrical power to be extracted from the electrical energy source 30 during a predetermined time period.

[0110] For example, this step comprises the operation STP1.1 of the electric motor 20 in motor mode.

[0111] The controller 55 may possibly control the motor electricity 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.

[0112] Additionally, or alternatively, the controller 55 may control the electricity supply 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.

[0113] The predetermined time period may possibly be fixed or calculated, for example by the controller 55. According to one illustration, the controller 55 is configured to calculate the predetermined time period as a function of an outside temperature measured with a temperature sensing device.

[0114] Therefore, before and/or during and/or after this extraction of an electrical energy or an electrical power, the monitoring phase Phas comprises determining STP2, for the electrical accumulators 31, respective initial values Vmes for an operating parameter.

[0115] Therefore, the monitoring phase Phas comprises calculating STP3 an average value Vmoy from the initial values Vmes, using the controller 55.

[0116] According to a first alternative that can be implemented with the system of FIG. 2, the sensor 55 measures an initial electrical voltage Vmes1 at the terminals 321 and 331 of the first accumulator 311, a second initial electrical voltage Vmes2 at the terminals 322 and 332 of the second accumulator 312 and a third initial electrical voltage Vmes3 at the terminals 323 and 333 of the third accumulator 313.

[0117] For each electrical accumulator 30, the initial value Vmes may be the electrical voltage measured in real time and at a predetermined instant, or may be equal to an average of the electrical voltages measured during said predetermined time period.

[0118] The initial electrical voltages Vmes may be stored in a memory of the controller 55 or in another memory.

[0119] Therefore, the monitoring phase Phas comprises calculating STP3 an average value Vmoy from the initial electrical voltages Vmes, using the controller 55.

[0120] The average value Vmoy is, for example, equal to the sum of the initial electrical voltages Vmes divided by said number Nbr. According to the example in FIG. 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.

[0121] According to a second alternative that can be implemented with the system of FIG. 2, the sensor 50 measures, for each electrical accumulator 31, a primary electrical voltage and a secondary electrical voltage respectively before and after the extraction, while on the ground, of an electrical energy or an electrical power to be extracted from the electrical energy source 30 during a predetermined time period. For each electrical accumulator 31, the controller 55 calculates the associated initial value Vmes, this initial value Vmes being equal to a difference between the primary electrical voltage and the secondary electrical voltage.

[0122] The average value Vmoy is, for example, equal to the sum of the initial values Vmes divided by said number Nbr.

[0123] According to a third alternative that can be implemented with the system of FIG. 2, the sensor 50 measures, for each electrical accumulator 31, a primary electrical voltage and a secondary electrical voltage respectively before and after the extraction, while on the ground, of an electrical energy or an electrical power to be extracted from the electrical energy source 30 during a predetermined time period. For each electrical accumulator 31, the controller 55 calculates the associated initial value Vmes, this initial value Vmes being an electrical capacitance that is a function of a difference between the primary electrical voltage and the secondary electrical voltage.

[0124] The average value Vmoy is, for example, equal to the sum of the initial values Vmes divided by said number Nbr.

[0125] According to a fourth alternative that can be implemented with the system of FIG. 2, the sensor 50 measures, for each electrical accumulator 31, a primary electrical voltage and a secondary electrical voltage respectively before and after the extraction, while on the ground, of an electrical energy or an electrical power to be extracted from the electrical energy source 30 during a predetermined time period. For each electrical accumulator 31, the controller 55 calculates the associated initial value Vmes, this initial value Vmes being an electrical resistance that is a function of a difference between the primary electrical voltage and the secondary electrical voltage.

[0126] The average value Vmoy is, for example, equal to the sum of the initial values Vmes divided by said number Nbr.

[0127] According to a fifth alternative, the sensor 50 measures, for each electrical accumulator 31, a temperature inside this electrical accumulator 31 at least during, and indeed also before and/or after the extraction, while on the ground, of an electrical energy or an electrical power to be extracted from the electrical energy source 30 during a predetermined time period. For each electrical accumulator 31, the controller 55 calculates the associated initial value Vmes, this initial value Vmes being a function of said change in temperature. For example, the operating parameter is the directing coefficient of a slope of a curve described by the measured temperature.

[0128] The average value Vmoy is, for example, equal to the sum of the initial values Vmes divided by said number Nbr.

[0129] Irrespective of how the initial values Vmes and the average value Vmoy are assessed and in reference to FIG. 3, the monitoring phase Phas also comprises determining STP4 a minimum value Vmin. The controller 55 can determine the minimum value Vmin, this minimum value Vmin being equal to the lowest of the measured initial values Vmes.

[0130] Therefore, 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 prohibition for the aircraft 1 when said difference Diff is greater than or equal to the threshold S.

[0131] By way of illustration, according to the example of the first alternative and the example of FIG. 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.

[0132] If the threshold is fixed at 0.3 Volts, 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. The flight is then prohibited. A maintenance action may then be triggered.

[0133] If the threshold is fixed at 0.6 Volts, the difference between the average electrical voltage Vmoy and the minimum electrical voltage Vmin is less than the threshold. The flight is then authorized.

[0134] In order to authorize the flight, the controller 55 can transmit a flight authorization signal when the difference between the value Vmoy and the minimum value Vmin is less than the threshold S. Upon receiving the flight authorization signal, the alerter 60 may then either not generate any alert, if the alerter 60 only transmits an alert in the event of prohibition, or generate an alert carrying the flight authorization.

[0135] In order to prohibit the flight, the controller 55 can transmit a flight prohibition signal when the difference between the average value Vmoy and the minimum value Vmin is greater than or equal to the threshold S. Upon receiving the flight prohibition signal, the alerter 60 may then either not generate any alert, if the alerter 60 only transmits an alert in the event of flight authorization, or generate an alert carrying the flight prohibition.

[0136] According to another aspect, the threshold may be fixed or may vary depending on the situation in question. For example, a pilot may operate a human-machine mission interface in order 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 that stores a said value of the threshold S for each mission.

[0137] According to one possibility, the controller 55 may calculate the threshold as a function of a temperature in the electrical energy source measured with a temperature sensor, a state of health of the electrical energy source assessed with a standard monitoring sensor, a state of charge of the electrical energy source assessed with a standard charge sensor, and/or an age of the electrical energy source assessed with a standard timer device.

[0138] The value of the threshold S or a law allowing this value to be calculated as a function of one or several parameters may be established by tests or simulations, for example.

[0139] In order to assess the value of the threshold S, for example for a specific mission or for certain values of certain parameters, the method may possibly comprise a preliminary phase STP0. This preliminary phase STP0 may comprise the extraction STP0.1, while on the ground, of the electrical energy or the electrical power to be extracted, as referred to above, from the electrical energy source 30 during the predetermined time period as referred to above. For example, this step STP0.1 comprises operating the electric motor 20 in motor mode or supplying electricity to an electrical load 75 as in the step STP1 described above.

[0140] The preliminary phase STP0 comprises measuring STP0.2, with the sensor 50, for the electrical accumulators 31, respective reference values Vref, each reference electrical voltage Vref according to the first alternative being measured at the terminals 32, 33 of the associated electrical accumulator 31.

[0141] The reference values Vref are stored for subsequent processing, for example in a memory of the controller 55 or another processing unit.

[0142] The preliminary phase STP0 comprises a step STP0.3 consisting in rendering an electrical accumulator 31 inoperative, for example the electrical accumulator 311 in FIG. 2, in order to assess the value of the threshold. For example, an operator modifies the wiring of the electrical energy source 30 in order to disconnect the electrical accumulator 311 in question, or the controller 55 acts on one or more switches or an equivalent in order to achieve the same effect.

[0143] Therefore, the preliminary phase STP0 comprises extracting STP0.4, while on the ground, electrical energy or electrical power to be extracted from the electrical energy source 30 during the predetermined time period in the presence of an electrical accumulator 31 that has been rendered inoperative, i.e., the first electrical accumulator 311 according to the example in question, and measuring STP0.5 respective test values Vtest for the electrical accumulators 31.

[0144] The reference steps STP0.1 and STP0.2 are reproduced with an inoperative electrical accumulator 31 in order to simulate a malfunction of the electrical energy source 30.

[0145] A processing unit and, for example, the controller 55 then determines, for each electrical accumulator 31 different from the electrical accumulator that has been rendered inoperative, a deviation between the reference value Vref and the corresponding test value Vtest.

[0146] FIG. 4 shows the variation in the reference electrical voltage Vref and the test electrical voltage Vtest over time in the context of the first alternative. This FIG. 4 shows time on the X-axis and electrical voltage on the Y-axis. The curve C1 represents the reference electrical voltage Vref and the curve C2 represents the test electrical voltage Vtest.

[0147] It can be seen that, at each instant, a deviation ECT separates the curve C1 and the curve C2. Indeed, in the event that an electrical accumulator 31 fails, the electrical energy or the electrical power extracted at the other electrical accumulators 31 is greater than when none of the electrical accumulators 31 has failed.

[0148] The method therefore comprises determining said threshold S as a function of said voltage deviation, for example using a processing unit or indeed the controller 55.

[0149] The threshold S may possibly be equal to half of the greatest deviation in voltage among the recorded deviations in voltage.

[0150] Naturally, the present disclosure is subject to numerous variations as regards its implementation, while remaining within the scope of the claims. Although several embodiments are described above, it should readily be understood that it is not conceivable to identify exhaustively all the possible embodiments. It is naturally possible to replace any of the means described with equivalent means without going beyond the ambit of the present disclosure and the claims.