Estimating energy state of battery

Abstract

The invention relates to estimating a state of energy (SOE) at a specific time, comprising: receiving (602) a measured value of a temperature (T) of a cell (111), a measured value of a voltage (U) of the cell (111) and a measured value of a current (I) exchanged by the cell (111); estimating an internal resistance (R) of the cell (111); estimating an open circuit voltage (OCV) of the cell (111); estimating the total energy (Etot) delivered by the cell (111) until the specific time; estimating the maximum energy (Emax) that can be delivered by the cell (111), assuming that the temperature (T) and the current (I) remain constant; and subtracting the estimated total delivery energy (Etot) from the estimated maximum energy (Emax).

Description

Technical Field

[0001] The invention relates to a method for estimating the energy state of a cell of a battery, and to an associated computer program, a device and an aircraft. Background Art

[0002] The state of energy (SOE) of a battery cell indicates the energy available in the cell, which concept refers to the available energy, which is different from the total stored energy because part of the total stored energy may not be available.

[0003] SOE can be expressed as an absolute value (Watt-hours, Wh) or as a percentage relative to the maximum energy the battery can hold. SOE is not a measurable quantity and must therefore be estimated from available measurements on the cell: the current exchanged between the cell terminals, the voltage at the cell terminals, and the temperature of the battery.

[0004] To this end, it is known to use a neural network to give the SOE at a given moment based on the current, voltage and temperature at that moment.

[0005] However, such neural networks are not deterministic systems and are difficult to certify in aviation, especially in hybrid or all-electric aircraft, when the propulsion system uses batteries.

[0006] It is therefore an object of the present invention to provide an alternative method for estimating the energy state of a cell of a battery, which method can be certified. Summary of the invention

[0007] The invention therefore proposes a method for estimating the energy state of a cell of a battery at a given moment, the cell having two terminals, characterized in that the method comprises:

[0008] - receiving at a given moment the measured values ​​of the temperature of the cell, the measured values ​​of the voltage at the terminals of the cell and the measured values ​​of the current exchanged by the cell between the terminals;

[0009] - Estimate the internal resistance of the cell at a given moment;

[0010] - estimating the open circuit voltage of the cell at a given moment based on the measured voltage and current and based on the estimated internal resistance, for example, by adding the voltage of the internal resistance generated by the measured current passing through the internal resistance to the measured voltage to estimate the open circuit voltage;

[0011] - using a predefined correlation between the value of the total delivered energy delivered by the cell and the values ​​of the temperature, the current and the open circuit voltage, estimating the total delivered energy delivered by the cell up to a given moment, from the measured temperature and current, and from the estimated open circuit voltage;

[0012] - using predefined correlations and assuming that the measured values ​​of temperature and current at a given moment remain constant, estimate the maximum energy that can be delivered by the cell; and

[0013] - Estimate the energy state of the cell at a given moment by subtracting the estimated total delivered energy from the estimated maximum energy.

[0014] The present invention may also include one or more of the following additional features in any technically possible combination:

[0015] Advantageously, the internal resistance at a given moment is estimated based on voltammetry.

[0016] Still advantageously, an estimate of the internal resistance at a given moment includes:

[0017] - using a predefined correlation between the value of the internal resistance and the value of the temperature and the value of the current, to make an a priori estimate of the internal resistance at a given moment, based on the temperature and the current measured at that moment; and

[0018] -Correct the a priori estimate by multiplying it by a correction ratio, which is the ratio between:

[0019] the internal resistance at the previous time, estimated by voltammetry; and

[0020] The internal resistance at a previous moment is estimated from the temperature and current measured at the previous moment, using a predefined association between the value of the internal resistance and the value of the temperature and the value of the current.

[0021] Still advantageously, the estimation of the internal resistance at a given moment is performed independently of the state of charge of the cell.

[0022] Still advantageously, the predefined correlation between the value of the total energy delivered by the cell and the values ​​of the temperature, the current and the open-circuit voltage is in the form of a table.

[0023] Still advantageously, for several combinations of temperature and current, the table gives the total delivered energy as a function of the open circuit voltage at constant temperature and current.

[0024] Still advantageously, under the conditions of temperature and current measured at a given moment, the maximum energy is the total energy delivered by the minimum open circuit voltage provided by the predefined association.

[0025] The present invention also proposes a computer program, which can be downloaded from a communication network and / or recorded on a computer-readable medium, characterized in that the computer program includes instructions, and when the program is executed on a computer, the instructions are used to execute the steps of the method according to the present invention.

[0026] The present invention also proposes a device for estimating the energy state of a cell of a battery at a given moment, the cell having two terminals, between which an electrical system is connected, characterized in that the device comprises:

[0027] - a module for receiving, at a given moment, the measured values ​​of the temperature of the cell, the measured values ​​of the voltage at the terminals of the cell and the measured values ​​of the current exchanged by the cell between the terminals;

[0028] -Module for estimating the internal resistance of a cell at a given moment;

[0029] - a module for estimating the open circuit voltage of the cell at a given moment based on the measured voltage and current and based on the estimated internal resistance, for example, by adding the voltage of the internal resistance generated by the measured current passing through the internal resistance to the measured voltage;

[0030] - a module for estimating the total energy delivered by the cell from the measured temperature and current, and from the estimated open circuit voltage, using a predefined correlation between the value of the total delivered energy delivered by the cell and the values ​​of the temperature, the current and the open circuit voltage;

[0031] - a module for estimating the maximum energy delivered by a cell assuming that the temperature and current measured at a given moment remain constant; and

[0032] - A module for estimating the energy state of the cell at a given moment by subtracting the estimated total delivered energy from the estimated maximum energy.

[0033] The present invention also provides an aircraft, comprising:

[0034] - a battery comprising at least one cell having two terminals;

[0035] -Sensors to measure the temperature of the battery cells;

[0036] - sensors for measuring the current exchanged by the cell between its terminals;

[0037] - a sensor for measuring the voltage between the terminals of the cell; and

[0038] - A device according to the invention for estimating the energy state of a cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The invention will be better understood from the following description given by way of example and with reference to the accompanying drawings, in which:

[0040] Figure 1 is a functional view of an aircraft embodying the invention.

[0041] Figure 2 It is used to estimate Figure 1 Functional view of the modules of the computer program of the device for the energy state of the cells of the battery of an aircraft.

[0042] Figure 3 is a graph showing the variation of the total energy delivered by a cell as a function of the open circuit voltage of the cell for several combinations of temperature and exchange current of the battery.

[0043] Figure 4 It is an electrical diagram of a model of a battery cell.

[0044] Figure 5 Is used based on Figure 4 Block diagram of a method for calculating the relationship between total energy and open circuit voltage for several combinations of temperature and current in the model in FIG.

[0045] Figure 6 is a block diagram of a method for estimating the energy state of a battery. DETAILED DESCRIPTION

[0046] refer to Figure 1 , an example of an aircraft 100 embodying the present invention will now be described.

[0047] First, the aircraft 100 includes a turbomachine 102 having an output shaft 104 .

[0048] The aircraft 100 further comprises a fan 106 designed to propel the aircraft 100. In particular, the fan 106 is connected to the output shaft 104 of the turbine 102, such that the fan 106 can be driven by the turbine 102.

[0049] The aircraft 100 further comprises an electric machine 108 designed to operate, for example, as an electric motor to drive the output shaft 104 instead of or in addition to the turbine 102. Alternatively or additionally, the electric machine 108 is designed to operate as a generator to supply electrical energy through the rotation of the output shaft 104.

[0050] The aircraft 100 also includes a battery 110, which includes at least one battery cell 111. In the example described, a single battery cell 111 is provided. The battery cell 111 has two terminals 112, 114, between which an electrical system is connected. The electrical system is designed to selectively act as an electrical load, powered by the battery 110, and to act as a power source for recharging the battery 110. Alternatively, the electrical system can always act as an electrical load or always act as a power source. The electrical system includes, for example, an electric motor 108.

[0051] Aircraft 100 also includes a system 116 for monitoring battery cells 111 .

[0052] First, the monitoring system 116 includes a sensor 118 , which is used to measure the temperature T of the battery cell 111 .

[0053] The monitoring system 116 also includes a sensor 120 for detecting the current I exchanged (ie supplied or received) by the cell 111 via its terminals 112 , 114 .

[0054] The monitoring system 116 further comprises a sensor 122 for detecting a voltage U between the terminals 112 , 114 of the battery cell 111 .

[0055] Sensors 118 , 120 , 122 are designed to provide measurements of temperature T, current and voltage U, respectively, either directly or indirectly by being derived from one or more other physical quantities.

[0056] The monitoring system 116 further comprises a device 124 for monitoring the battery cell 111. The monitoring device 124 is specifically designed to estimate the state of charge (SOC) of the battery cell 111 based on the temperature T, current I and voltage U measured by the sensors 118, 120 and 122 respectively.

[0057] In the described example, the data processing device 124 is a computing system comprising a data processing unit 126 (e.g., a microprocessor) and a main memory 128 (e.g., RAM, an acronym for Random Access Memory) accessible by the data processing unit 126. The computing system also comprises, for example, a network interface and / or a computer-readable medium, for example, a local medium (e.g., a local hard disk 130) or a remote medium (e.g., a remote hard disk accessible via a communication network via a network interface) or a removable medium (e.g., a Universal Serial Bus (USB) key, or a Compact Disc (CD) or a Digital Versatile Disc (DVD)), which can be read with the aid of an appropriate computer system driver (e.g., a USB port or a CD and / or DVD disk drive). A computer program 132 containing instructions for the data processing unit 126 is stored on the medium 130 and / or can be downloaded via a network interface. The computer program 132 is configured to be loaded into the main memory 128, for example, so that the data processing unit 126 can execute its instructions. In order to more easily describe the computer program 132, the instructions will be described below as being organized into software modules. However, this expression does not presuppose a specific form of the computer program, which can be in any form.

[0058] Alternatively, all or some of these modules may be implemented in the form of hardware modules, ie in the form of electronic circuits, such as micro-wires, which do not involve a computer program.

[0059] refer to Figure 2 , an example of an embodiment of the computer program 132 will now be described.

[0060] First, the computer program 132 includes a module 202, which is designed to receive the measured values ​​T(t), U(t), and I(t) of the temperature T, the voltage U, and the current I at the time t from the sensors 118, 120, and 122, respectively. For example, these measured values ​​T(t), U(t), and I(t) are obtained at the time t. Optionally, one or more of these measured values ​​can be obtained before the time t and used again at the time t.

[0061] The computer program 132 also includes a module 204 designed to estimate the internal resistance R of the battery cell 111 at time t, for example based on a measured value T(t) of the temperature T and a measured value I(t) of the current I (preferably independent of the state of charge (SOC) of the battery cell 111).

[0062] Preferably, the module 204 is designed to estimate the internal resistance R at least at certain times t by voltammetric measurement, for example by dividing the measured change in voltage U by the measured change in current I:

[0063] [Mathematical formula 1]

[0064] R(t)=ΔU(t) / ΔI(t)

[0065] For example, the computer program 132 may include a table 205 that relates the value of the internal resistance R to the value of the temperature T and the current I, for example, for a predefined and arbitrary state of charge SOC of the battery cell 111, for example, for a state of charge SOC of 50%. The form of the table 205 is as follows (the current I is represented as the rated current of the battery cell, and C represents the "current rate"):

[0066] [Table 1]

[0067] R(Ω) T(℃) I(C) 0.1 25 1 … … …

[0068] Then, the module 204 can be designed to calculate the estimated value R(t) of the resistance R and another estimated value R obtained from the measured value T(t) of the temperature T and the measured value I(t) of the current I using the table 205. table The correction ratio K between (t) is achieved, for example, by interpolation:

[0069] [Mathematical formula 2]

[0070] K=R(t) / Rtable (t)

[0071] In this case, for other times t, the module 204 is designed to make an a priori estimate R of the internal resistance R for a given time t based on the measured value T(t) of the temperature T and the measured value I(t) of the current I, for example using the table 205. table (t). For example, module 204 is designed to determine the prior estimate R by difference table (t), then, module 204 can be designed to calculate the prior estimate R table (t) Multiply by the ratio K obtained previously as described above to correct the a priori estimate R table (t):

[0072] [Mathematical formula 3]

[0073] R(t)=K·R table (t)

[0074] It should be understood that the estimation of the internal resistance R in the table 205 is performed under the assumption that the state of charge SOC of the battery cell 111 is a predefined and arbitrary value, even if the actual state of charge of the battery cell 111 at the moment in question is different therefrom.

[0075] Alternatively, the correlation may be presented in the form of a formula correlating the internal resistance R with the temperature T and the current I, rather than in the form of table 205 .

[0076] Since the internal resistance R is measured at least at certain moments, it is possible to quickly take into account unpredictable variations of the internal resistance R over time, caused by the aging of the cell 111 and therefore also by the way in which the cell 110 is used. Such a rapid consideration is not possible with a neural network, which is a "black box" that does not include a modifiable parameter representing the internal resistance. At best, the neural network should be retrained during use, but this would take time and would not allow monitoring variations of the internal resistance R.

[0077] The computer program 132 further includes a module 206, which is designed to estimate the open circuit voltage OCV of the battery cell 111 at time t based on the measured value U(t) of the voltage U, the measured value I(t) of the current I, and the estimated value R(t) of the internal resistance R. Specifically, the module 206 is designed to add the voltage generated by the current I passing through the internal resistance R to the measured value U(t) of the voltage U:

[0078] [Formula 4]

[0079] OCV(t)=U(t)+R(t)·I(t)

[0080] Where OCV(t) is the estimated value of the open circuit voltage OCV at time (t).

[0081] The computer program 132 also includes, for example, the total energy E delivered by the cell 111 tot The table 208 relates the value of to the value of temperature T, the value of current I and the value of open circuit voltage OCV. Preferably, for several combinations of temperature T and current I, the table gives the total delivered energy E at constant temperature T and current I. tot As a function of the open circuit voltage OCV. For example, Table 208 takes the following form:

[0082] [Table 2]

[0083]

[0084] According to the table above, the minimum open circuit voltage OCV at a temperature T of 0°C and a current I of 1C is 3.13V, and the minimum open circuit voltage OCV is related to the total delivered energy E of 8.724J. tot (hence corresponding to the maximum energy that can be delivered E max ) because no energy (box “NA”) is associated with the previous value of the open circuit voltage OCV (3.12 V).

[0085] Optionally, the correlation can be made by converting the total delivered energy E tot The temperature T, the current I, and the open circuit voltage OCV are presented in the form of a formula rather than in the form of a table 208 .

[0086] The computer program 132 further comprises a module 210 designed to estimate the total energy E delivered by the cell 111 up to the time t, using the table 208, from the measured value T(t) of the temperature T, the measured value I(t) of the current I and the estimated value OCV(t) of the open circuit voltage OCV. tot (t). For example, module 210 is designed to estimate the total energy E by interpolation. tot (t).

[0087] The computer program 132 further comprises a module 212, which is designed to estimate the maximum energy E that can be delivered by the cell 111 for a time t, assuming that the temperature T and the current I keep their measured values ​​T(t), I(t) constant at a time t. max (t). For example, module 212 is designed to use table 208. In fact, for each combination of temperature T and current I, the open circuit voltage OCV decreases, while the total energy E delivered tot Increases until the open circuit voltage OCV reaches a minimum value, below which the battery cell 111 can no longer supply electrical energy. max is the minimum open circuit voltage OCV for the considered temperature T and current I. min The total energy delivered Etot In this way, for the measured value T(t) of the temperature T and the measured value I(t) of the current I, by looking up the minimum open circuit voltage OCV in the table 208 min and the associated total transport energy E tot , the maximum energy E can be derived from Table 208 max .

[0088] The computer program 132 also includes a module 214 designed to generate a maximum energy E max (t) minus the total transport energy E tot (t) to estimate the energy state SOE(t) of the battery cell 111 at time t:

[0089] [Formula 5]

[0090] SOE(t)=E max (t)-E tot (t)

[0091] refer to Figure 3 , shows that for several combinations of temperature T and current I, the total delivered energy E tot Examples of curves related to open circuit voltage OCV. These curves therefore represent the data recorded in table 208.

[0092] refer to Figure 4 , an example of a model 400 of the battery cell 111 will now be described.

[0093] The model 400 comprises a plurality of blocks connected in series between two terminals 114 , 116 . The cell 111 provides a voltage U between these terminals 114 , 116 and exchanges a current I via these terminals 114 , 116 .

[0094] The first block includes a voltage source U oc , the voltage source represents the open circuit voltage of the battery cell 111, that is, the voltage of the battery cell 111 when there is no load at all.

[0095] The second block includes a series resistor R s , which represents all purely resistive contributions such as electrolyte, current collector, and contact resistances.

[0096] The third block includes resistors R connected in parallel with each other surf and capacitor C surf , which represents the surface resistance and capacitance associated with the voltage drop between the active material surface and the electrolyte, which is caused by charge transfer and the solid electrolyte interphase (SEI). Therefore, the resistance R surf and capacitor C surfThe time constant T associated with surface phenomena (load transfer, SEI, and double layer) is defined as surf =R surf C surf This is a fast dynamic process, usually less than one second.

[0097] Each of the n blocks (n is greater than or equal to 1) includes a resistor R diff and capacitor C diff , the resistance and capacitance represent the diffusion phenomenon of lithium ions in the electrolyte and lithium atoms in the two electrodes. The resistance R of each of these n blocks diff and capacitor C diff The time constant T associated with the diffusion phenomenon is defined as diff =R diff C diff This is a slow, dynamic process that can last for seconds or minutes.

[0098] In addition to the voltage source U oc Independent of the current I, all these parameters depend on the state of charge SOC of the cell 111, the temperature T of the cell 111 and the current I in the cell 111. Therefore, the model 400 comprises, for example, a table for each of them, which gives the value of the parameter in question as a function of the state of charge SOC, the temperature T and, if applicable, the current I.

[0099] In model 400, the internal resistance R of the battery cell 111 is equal to the resistance R s , resistor R surf and the resistance R of n blocks diff sum:

[0100] [Mathematical formula 3]

[0101] R=R s +R surf +R diff，1 +…+R diff，n

[0102] refer to Figure 5 , an example of a method (500) for determining table 208 will now be described.

[0103] In step 502, a temperature value T and a current I are selected.

[0104] In step 504 , the temperature T and the current I are kept constant at their selected values, and a complete discharge of the battery cell 111 is simulated using the model 400 .

[0105] In step 506, the electrical energy supplied to the battery cell during the simulation time and the heat energy dissipated by the Joule effect are calculated based on the simulation results. Then, the total energy E supplied at each of the several moments in the simulation is calculated as totIt is calculated as the sum of the electrical energy supplied and the thermal energy dissipated at the simulation moment in question.

[0106] In step 508 , an open circuit voltage OCV is calculated for each simulation time instant based on the simulation results.

[0107] In step 510, for each simulation time, the total delivered energy E is recorded in table 208. tot The value of and the associated open circuit voltage OCV, as well as the value of temperature T and the value of current I.

[0108] The method 500 then returns to step 502 to select new values ​​for the temperature T and the current I.

[0109] refer to Figure 6 , an example of a method 600 for estimating the state of energy SOE(t) of the battery cell 111 at time t will now be described.

[0110] In step 602 , the module 202 receives the measured values ​​T(t), U(t), I(t) of the temperature T, the voltage U, and the current I at the time t.

[0111] In step 604 , the module 204 estimates the internal resistance R(t) of the battery cell 111 at time t.

[0112] In step 606 , the module 206 estimates the open circuit voltage OCV of the battery cell 111 at time t according to the measured value U(t) of the voltage U, the measured value I(t) of the current I, and the estimated value R(t) of the internal resistance R.

[0113] In step 608, the module 210 estimates the total energy E delivered by the battery cell 111 up to time t based on the measured value T(t) of the temperature T, the measured value I(t) of the current I, and the estimated value OCV(t) of the open circuit voltage OCV. tot (t).

[0114] In step 610, assuming that the temperature T and the current I remain constant, the module 212 estimates the maximum energy E that can be delivered by the battery cell 111 at time t. max (t).

[0115] In step 612, module 214 calculates the energy E max (t) minus the total transport energy E tot (t) to estimate the state of energy SOE(t) of the battery cell 111 at time t.

[0116] In summary, it should be noted that the present invention is not limited to the above-described embodiments. In fact, it is obvious to those skilled in the art that various modifications can be made to the above-described embodiments according to the teachings of this disclosure.

[0117] In the foregoing detailed presentation of the invention, the terms used should not be construed to limit the invention to the embodiments disclosed in this specification, but should be construed to include all equivalents that a person skilled in the art could anticipate by applying common sense to the implementation of the teachings of the present disclosure.

Claims

1. A method (600) for estimating the state of energy (SOE) of a cell (111) of a battery (110) at a given time (t), the cell (111) having two terminals (114, 116), characterized in that: The method comprises: receiving (602) a measured value of a temperature (T) of the battery cell (111) at the given time (t), a measured value of a voltage (U) at the terminals (112, 114) of the battery cell (111), and a measured value of a current (I) exchanged by the battery cell (111) between the terminals (114, 116); estimating (604) an internal resistance (R) of the battery cell (111) at the given time (t); estimating (606) an open circuit voltage (OCV) of the cell (111) at the given time (t) based on the measured voltage (U) and current (I) and based on the estimated internal resistance (R), for example, by adding a voltage of the internal resistance (R) generated by the measured current (I) passing through the internal resistance (R) to the measured voltage (U); The total energy (E) delivered by the battery cell (111) is used tot ) with the values ​​of temperature (T), current (I) and open circuit voltage (OCV), and based on the measured temperature (T) and current (I), and based on the estimated open circuit voltage (OCV), estimating (608) the total energy (E) delivered by the cell (111) up to the given moment (t) tot ); Using the predefined relationship (208), and assuming that the measured values ​​of the temperature (T) and the current (I) at the given time (t) remain constant, the maximum energy (E) that can be delivered by the cell (111) is estimated (610). max );as well as By estimating the maximum energy (E max ) minus the estimated total delivered energy (E tot ) to estimate (612) the state of energy (SOE) of the battery cell (111) at the given moment (t).

2. The method (600) of claim 1, wherein: The internal resistance (R) at the given time (t) is estimated based on voltammetry.

3. The method (600) of claim 1, wherein: Estimating (604) the internal resistance (R) at the given time (t) comprises: Using a predefined correlation (205) between the value of the internal resistance (R) and the value of the temperature (T) and the value of the current (I), a priori estimate of the internal resistance (R) at the given time (t) based on the temperature (T) and the current (I) measured at the given time (t); and The a priori estimate is corrected by multiplying it by a correction ratio (K), which is the ratio between: the internal resistance (R) at the previous time, estimated by voltammetry; and Using the predefined association (205) between the value of the internal resistance (R) and the value of the temperature (T) and the value of the current (I), the internal resistance (R) at the previous moment is estimated based on the temperature (T) and the current (I) measured at the previous moment.

4. The method (600) according to any one of claims 1 to 3, wherein: The estimation (604) of the internal resistance (R) at the given time (t) is performed independently of the state of charge (SOC) of the battery cell (111).

5. The method (600) according to any one of claims 1 to 4, wherein: The total energy (E) delivered by the battery cell (111) tot ) and the values ​​of the temperature (T), the current (I) and the open circuit voltage (OCV) are in the form of a table.

6. The method (600) of claim 5, wherein: For several combinations of the temperature (T) and the current (I), the table gives the total delivered energy (E tot ) is a functional relationship between the open circuit voltage (OCV).

7. The method (600) according to any one of claims 1 to 6, wherein: Under the conditions of the temperature (T) and current (I) measured at the given time (t), the maximum energy (E max ) is the minimum open circuit voltage (OCV) provided by the predefined association (208) min )The total energy delivered (E tot ).

8. A computer program (132), which can be downloaded from a communication network and / or which is recorded on a computer-readable medium, characterized in that: The computer program comprises instructions for executing the steps of the method (600) according to any one of claims 1 to 7 when the program is executed on a computer.

9. A device for estimating the state of energy (SOE) of a cell (111) of a battery (110) at a given time (t), the cell (111) having two terminals (114, 116) between which an electrical system (108) is connected, characterized in that: The device comprises: A module (202) for receiving a measured value of a temperature (T) of the battery cell (111) at the given time (t), a measured value of a voltage (U) at the terminals (112, 114) of the battery cell (111), and a measured value of a current (I) exchanged by the battery cell (111) between the terminals (114, 116); A module (204) for estimating the internal resistance (R) of the battery cell (111) at the given time (t); A module (206) for estimating an open circuit voltage (OCV) of the cell (111) at the given time (t) based on the measured voltage (U) and current (I) and based on the estimated internal resistance (R), for example, by adding a voltage generated by the measured current (I) passing through the internal resistance (R) to the measured voltage (U) to estimate the open circuit voltage; A module (210) for using the total energy (E) delivered by the battery cell (111) tot ) with the values ​​of temperature (T), current (I) and open circuit voltage (OCV), and estimating the total energy (E) delivered by the cell (111) based on the measured temperature (T) and current (I) and the estimated open circuit voltage (OCV). tot ); A module (212) for estimating the maximum energy (E ) that can be delivered by the cell (111) assuming that the measured values ​​of the temperature (T) and the current (I) at the given time (t) remain constant. max );as well as Module (214) for calculating the maximum energy (E max ) minus the estimated total delivered energy (E tot ) to estimate the state of energy (SOE) of the battery cell (111) at the given moment (t).

10. An aircraft (100), comprising: A battery (110) comprising at least one battery cell (111) having two terminals (112, 114); A sensor (118) for measuring a temperature (T) of the battery cell (111); A sensor (120) for measuring a current (I) exchanged between the terminals (112, 114) by the battery cell (111); A sensor (122) for measuring a voltage (U) between the terminals (112, 114) of the battery cell (111); and The device for estimating the state of energy (SOE) of the battery cell (111) according to claim 9.

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