Method for managing available state of charge of a battery

Abstract

One aspect of the present invention relates to a method (100) for managing the available state of charge (SOCDisp) of an aircraft battery, the method comprising the steps of: - obtaining (110) a first intermediate available state of charge (SOCDisp1) from a battery capacity table based on battery temperature; - obtaining (120) a second intermediate available state of charge (SOCDisp2) based on a stored state of charge, a first instantaneous voltage, an instantaneous open-circuit voltage, and a predetermined minimum permissible voltage; - measuring (130) a second instantaneous voltage Ucell across the battery terminals; and - determining (140) an available state of charge (SOCDisp) based on the first intermediate available state of charge (SOCDisp1), the second intermediate available state of charge (SOCDisp2), and the measured (130) second instantaneous voltage Ucell.

Description

Technical Field

[0001] The technical field is battery management, particularly the management of batteries on vehicles (especially aircraft).

[0002] This invention relates to a method and related system for managing the available state of charge of a battery. Background Technology

[0003] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, countries have already implemented, are implementing, or will implement various measures to limit carbon emissions. Specifically, an ambitious standard applies to both new and currently in-service aircraft, requiring the implementation of technological solutions to comply with existing regulations. The civil aviation industry has been committed for many years to contributing to addressing climate change through flight.

[0004] Technological research has led to significant improvements in the environmental performance of aircraft. The applicant has fully considered factors affecting all stages of design and development to produce more energy-efficient and environmentally friendly aerospace components and products, and to ensure that their integration and use in civil aviation have a moderate environmental impact, with the aim of improving aircraft energy efficiency. The applicant continues its efforts to reduce its climate impact by adopting environmentally friendly methods that minimize greenhouse gas emissions and by using development and manufacturing processes that reduce the environmental footprint of its activities.

[0005] This ongoing research and development effort focuses on next-generation aircraft engines, reducing aircraft weight—particularly through the materials used and lighter onboard equipment—developing electric technologies for propulsion, and finally, aviation biofuels.

[0006] In this context, it is essential to optimize the use and management of batteries within aircraft. Specifically, it is crucial to be able to manage the state of charge (SOC) of batteries. SOC (sometimes also called charge level and abbreviated as SOC) represents the amount of charge stored in a battery at a given moment. SOC is typically expressed as a percentage of the battery's total capacity, generally equal to the ratio of the charge accumulated in the battery at the considered moment to the maximum or nominal charge that can be stored in that battery, i.e., accumulated charge divided by the battery's total capacity (maximum or nominal charge).

[0007] Calculate the state of charge (SOC) stock The most commonly used method is the Coulomb method, which involves integrating the current over time. This is done when the initial state of charge (SOC) is known. stock,0 This applies when t is the time. Therefore, at a given time t, the state of charge (SOC) is... stock It can be expressed in ampere-hours (denoted as Ah) as follows:

[0008] [Formula 1]

[0009] The state of charge (SOC) can also be... stock It is expressed as a percentage relative to the total reference capacity of the battery.

[0010] State of charge (SOC) estimated by coulomb method stock Information about the capacity stored in the battery is provided. However, this information about the capacity stored in the battery is not sufficient, as a portion of this capacity may potentially be unavailable, especially at low temperatures and / or high currents. These variations in available capacity are caused by voltage changes; and voltage changes are a result of changes in current or internal resistance, which is a factor influencing the battery's temperature, current, and state of charge (SOC). stock The voltage across the battery varies as a function of the battery impedance and the current flowing through it. In fact, when the discharge current flows through the battery, the voltage across the battery terminals decreases proportionally to the battery impedance and the current flowing through the battery.

[0011] Figure 1 The diagram shows the voltage across the battery over time during 1C discharge at two different temperatures (10°C and 25°C). The thicker line corresponds to the 25°C temperature, while the thinner line corresponds to the 10°C temperature. Battery impedance increases with decreasing temperature, resulting in a larger voltage drop during discharge. Similarly, if the impedance were the same, the voltage drop would be greater at higher currents. It is important to note that battery discharge stops when the minimum permissible voltage is reached. However, for the same state of charge (SOC), the voltage drop will continue to increase. Stock If the current is large or the temperature is low, the voltage will be reached more quickly. In these cases, the state of charge (SOC) will be... Disp Lower.

[0012] Therefore, when managing batteries, it is essential to distinguish between the stored state of charge (SOC). Stock and available state of charge (SOC) Disp Theoretically, the state of charge (SOC) can be used. Disp It is the stored state of charge (SOC). Stock A function of temperature T and current I:

[0013] [Formula 2]

[0014] Therefore, the first problem to be solved is to determine the available state of charge (SOC). Disp The relationship between current and temperature, or finding another way to explain the effect of current and temperature on the available state of charge (SOC). Disp The impact.

[0015] Regarding temperature, a series of battery charge-discharge tests can be performed at sufficiently low currents—to avoid heating the battery during testing—in order to determine the limits of charge stored in the battery. Figure 2 The diagram illustrates the battery's available capacity over time in relation to charging or discharging operations. Region 1 corresponds to the capacity unavailable during charging over time. Region 3 corresponds to the capacity unavailable during discharging over time. Region 2 corresponds to the capacity available during both charging and discharging over time. The curve defining Regions 1 and 2 corresponds to the lower limit of battery capacity, and the curve defining Region 3 and 2 corresponds to the upper limit of battery capacity. For example, at the end of discharge at 0°C, approximately 0.24 Ah remains stored in the battery and is unavailable for discharge. Therefore, it can be inferred that the available state of charge (SOC) at 0°C is... Disp Compared to the state of charge (SOC) stored at 0°C Stock Less than 0.24 Ah. For example, an example of such a method is disclosed in French patent application FR3126812A1, filed by Safran Electrical and Power SAS, entitled “Procédé de surveillance d'un niveau decharge d'une batterie, et système de stockage associé” (Method for monitoring battery charge level and associated storage system).

[0016] However, this method cannot be used to study the dependence of available capacity on current, because high current will cause the battery to heat up, and therefore the measured capacity value cannot be correlated with a specific operating point.

[0017] To address this limitation, the available state of charge (SOC) must be determined. Disp At that time, high current must be taken into account.

[0018] In summary, the available state of charge (SOC) in the battery Disp With the battery's stored state of charge (SOC) Stock The differences are different and depend on temperature and current. The first set of known methods allows for determining the available state of charge (SOC) in a battery at different temperatures and under low constant current. Disp However, this cannot be done at high currents because high currents significantly increase the battery temperature, making it impossible to measure the available state of charge (SOC) at different currents for a given temperature. Disp Nevertheless, battery voltage is still directly affected by temperature and current. Furthermore, voltage is a primary criterion for stopping discharge. Therefore, this information can be used to determine the available state of charge (SOC) based on the stored SOC.Disp Even at high currents, the available state of charge (SOC) in a battery can be determined by taking into account the effects of temperature and current. Disp However, when the current is at a medium or high level, such methods tend to underestimate the battery's available state of charge (SOC). Disp .

[0019] Therefore, a usable state of charge (SOC) for managing batteries is needed. Disp The method is designed to at least partially solve the aforementioned problems of the prior art. Summary of the Invention

[0020] This invention provides a reliable method for managing the available state of charge (SOC). Disp The method and system provide a solution to the problems previously discussed, particularly by accurately determining the available state of charge (SOC) based on the following three data points. Disp :

[0021] - The first intermediate state of charge (SOC) obtained from the battery capacity table as a function of temperature. Disp1 ,

[0022] - The second intermediate state of charge (SOC) is obtained based on the stored state of charge, the first instantaneous voltage, the instantaneous open-circuit cell voltage (OCV), and the minimum permissible voltage. Disp2 ,as well as

[0023] - Second instantaneous voltage.

[0024] The first aspect of the present invention relates to a method for managing the available state of charge (SOC) of a battery. Disp The method includes the following computer-implemented steps:

[0025] - Obtain the first intermediate available state of charge (SOC) Disp1 The first intermediate state of charge (SOC) Disp1 It is obtained from a battery capacity table based on battery temperature, which allows for the determination of a lower limit and an upper limit of battery capacity for a set of predetermined temperatures.

[0026] The "lower limit" of battery capacity corresponds to the capacity stored at the end of a full discharge at the standard current, while the "upper limit" corresponds to the capacity stored at the end of a full charge at the standard current. The standard current can vary; for example, it can be a constant current C / 2 during discharge, and a constant current C / 2 followed by a constant voltage U during charging. max The constant pressure U max This corresponds to the predetermined maximum voltage required to ensure battery integrity.

[0027] - Obtain the second intermediate state of charge (SOC)Disp2 The second intermediate state of charge (SOC) Disp2 It is obtained based on the stored state of charge, the first instantaneous voltage, the instantaneous open-circuit battery voltage, and the minimum permissible voltage, which is a predetermined value.

[0028] - Measure the second instantaneous voltage U across the battery terminals cell ,as well as

[0029] - Based on the first intermediate available state of charge (SOC) Disp1 The second intermediate state of charge (SOC) is available. Disp2 and the measured second instantaneous voltage U cell Determine the available state of charge (SOC) Disp .

[0030] Therefore, with the help of this invention, the state of charge (SOC) of a battery can be reliably determined and managed across all possible ranges of possible states of charge. Disp The method according to the invention makes it particularly possible to accurately determine the state of charge (SOC) of a battery under high current conditions (i.e., conditions that cause the battery to heat up). Disp The performance variations of individual cells between medium / high SOC and low SOC are taken into account.

[0031] In addition to the features just discussed in the preceding paragraphs, a method according to one aspect of the invention may also include one or more of the following additional features, which may be considered individually or in any technically possible combination:

[0032] - Determine the available state of charge (SOC) Disp Includes: via the first intermediate available state of charge (SOC) Disp1 Second intermediate available state of charge (SOC) Disp2 Perform a weighted summation to calculate the available state of charge (SOC). Disp The weights of and depend on the measured second instantaneous voltage U. cell .

[0033] - The weighted sum is calculated as follows:

[0034]

[0035] in:

[0036] - t represents the current time.

[0037] - ,

[0038] - ,

[0039] - A predetermined minimum voltage to ensure battery integrity, and

[0040] - To ensure battery integrity, a predetermined maximum voltage is required.

[0041] - Obtain the first available intermediate state of charge (SOC) Disp1 Includes the following steps:

[0042] - Measure the current delivered by the battery.

[0043] - Measure the battery temperature.

[0044] - Using an electronic processing and control system, the total charge accumulated in the battery at the current moment is calculated via coulomb analysis, based on the total charge accumulated in the battery at previous times and as a function of the measured current.

[0045] - Calculate the stored state of charge, which is equal to the total charge currently accumulating in the battery divided by the maximum total charge that can accumulate in the battery.

[0046] - Calculate available charge based on the difference between the following two:

[0047] - The total charge currently accumulated in the battery, and

[0048] - Non-retrievable charge, which cannot be extracted from the battery at a given battery temperature, is determined based at least on the measured temperature using battery operating characteristics stored in the memory of the electronic processing and control system.

[0049] - Calculate the first intermediate available state of charge (SOC) Disp1 It is equal to the available charge divided by the maximum available charge, which is equal to the difference between the following two: on the one hand, the maximum achievable charge that can be stored to the maximum extent when the battery is charged at the stated temperature, and on the other hand, the unretrievable charge.

[0050] - Obtain a second intermediate available state of charge (SOC) Disp2 Includes the following steps:

[0051] - Determine the stored state of charge;

[0052] - Measure the battery temperature;

[0053] - The instantaneous open-circuit battery voltage is determined based on the mapping of the instantaneous open-circuit battery voltage as a function of the stored state of charge and battery temperature.

[0054] - Measure the first instantaneous voltage across the battery terminals;

[0055] - Determine the second intermediate usable state of charge (SOC) based on the stored state of charge, the first instantaneous voltage, the instantaneous open-circuit battery voltage, and the minimum permissible voltage. Disp2 The minimum allowable voltage is a data predetermined in the design.

[0056] - The method according to the invention further includes, based on the determined available state of charge (SOC) Disp To modify the battery operating conditions.

[0057] A second aspect of the invention relates to a battery management system comprising means for implementing the method according to the invention.

[0058] A third aspect of the invention relates to a computer program comprising instructions that, when executed by a computer, cause the computer to implement the method according to the invention.

[0059] A fourth aspect of the invention relates to a non-transient computer-readable data medium having a computer program according to the invention recorded thereon.

[0060] A better understanding of the invention and its various applications will be gained after reading the following description and reviewing the accompanying drawings. Attached Figure Description

[0061] The accompanying drawings are for illustrative purposes and not for limiting the scope of the invention.

[0062] - Figure 1 The illustration shows examples of a battery being discharged at 1C current at two different temperatures;

[0063] - Figure 2 The illustration shows an example of the stored capacity as a function of temperature at the end of charging and discharging.

[0064] - Figure 3 This is a flowchart illustrating an example of the steps of the method according to the present invention;

[0065] - Figure 4 The diagram illustrates an example of how the instantaneous voltage of a battery changes over time during battery discharge, as well as the stored state of charge (SOC). Stock Examples of processes that change over time;

[0066] - Figure 5 An example of the result that can be obtained using the method according to the invention is illustrated. Detailed Implementation

[0067] Unless otherwise stated, the same element appearing in different figures has the same reference numeral.

[0068] Figure 3This is a block diagram illustrating the steps of an example of method 100 according to the present invention. Optional steps of the example of method 100 are indicated by dashed rectangular boxes.

[0069] Method 100 is a method for managing the available state of charge (SOC) of one or more batteries. Disp The method involves accurately determining the available state of charge (SOC). Disp This enables more reliable management of the available state of charge (SOC) of one or more batteries. Disp .

[0070] The battery used in application method 100 can be, for example, an aircraft-borne battery. This battery is used, for example, to store electrical energy and / or to supply electrical energy to equipment within an aircraft turbine engine. The battery is used, for example, for electric propulsion functions within a turbine engine. Alternatively, the battery is used in automotive, railway, marine, and other similar systems.

[0071] The first step 110 of method 100 includes obtaining a first intermediate available state of charge (SOC). Disp1 In this application, the term "obtain" may mean "receive" and / or "calculate" and / or "determine by implementing a method". This first intermediate state may be the state of charge (SOC). Disp1 This is obtained from the battery capacity table as a function of battery temperature. Therefore, the battery capacity table allows for the determination of a lower limit and an upper limit of battery capacity for a set of predetermined temperatures. Figure 2 The middle figure shows an example of this type of capacity table.

[0072] In the first example, the battery capacity table is obtained according to a first scheme. The first scheme is performed at different temperatures of the battery, referred to as "test temperatures," covering the battery's operating range. The first scheme, for each test temperature within a set of test temperatures, includes the following steps:

[0073] - 1 - Stabilize the battery at the test temperature.

[0074] - 2 - Fully charge the battery using, for example, a CCCV (constant current-constant voltage) scheme, which involves charging at a low current (e.g., current C / 2) to the battery's maximum voltage, and then charging at a fixed maximum voltage until the battery current drops to a lower value, for example, equal to C / 20.

[0075] - 3 - Pause, for example, a pause for a duration between 30 minutes and 3 hours, such as 1 hour, and

[0076] - 4 - The battery is fully discharged using, for example, a CC scheme (constant current), which involves discharging at, for example, a current of C / 2.

[0077] The final step, step 4, provides the battery capacity at the test temperature. Therefore, in this first example, it is assumed that after a full charge, especially when a CCCV-type scheme is used in step 2, the amount of charge stored in the battery is the same, independent of temperature. Next, preferably, at the point measured in step 4, the fitted form is Q=f Q The formula (T) is used, where Q is the battery capacity and T is the battery temperature. This formula depends on the results obtained and can, for example, be a cubic polynomial. Finally, the minimum battery capacity Q can be calculated using the following formula. min and maximum capacity Q max The limit:

[0078] [Formula 4]

[0079] [Formula 5]

[0080] This first example yields the same result as... Figure 2 The capacity table shown is similar to the one shown, the difference being the maximum battery capacity Q. max The capacity is the same at all temperatures; therefore, the capacity difference between temperatures is entirely attributable to the end of the discharge.

[0081] In the second example, the battery capacity table is obtained according to a second scheme. The second scheme is performed at different temperatures, referred to as "test temperatures," covering the battery's operating range. For each test temperature within this set of test temperatures, the second scheme includes the following steps:

[0082] - 1 - Stabilize the battery at the test temperature.

[0083] - 2 - The battery is fully charged using, for example, a CCCV scheme, which involves charging at a current C / 2 to the maximum battery voltage, and then charging at a fixed maximum voltage until the battery current drops to, for example, a current value equal to C / 20.

[0084] - 3 - Pause, for example, a pause for a duration between 30 minutes and 3 hours, such as 1 hour.

[0085] - 4 - The battery is fully discharged using, for example, a CC scheme, which includes, for example, discharging at a current of C / 2.

[0086] - 5 - Stabilize the battery at a reference temperature, such as 25°C, and

[0087] - 6 - Use, for example, a CCCV scheme to fully charge the battery, which includes, for example, charging to the maximum battery voltage at a current C / 2, and then charging at a fixed maximum voltage until the battery current drops to, for example, a current value equal to C / 20.

[0088] - 7 - Pause, for example, a pause for a duration between 30 minutes and 3 hours, such as 1 hour.

[0089] - 8 - Stabilize the battery at the test temperature, and

[0090] - 9 - Use, for example, a CC scheme to fully discharge the battery, which includes, for example, discharging at a current equal to C / 2.

[0091] Therefore, in this second example, it is not assumed that the amount of charge stored in the battery is the same after a full charge, regardless of temperature. In fact, as... Figure 2 As illustrated in the figure, the second example allows the difference in battery capacity between different temperatures to be attributed partly to charging and partly to discharging.

[0092] Steps 1 to 4 of the second scheme are the same as those of the first scheme. Steps 5 to 9 assess the proportion of battery capacity differences caused by the discharge. For this reason, the second full charge of the battery in step 6 is performed at a reference temperature that is the same for all test temperatures, thus establishing a common starting point. Next, it is needed that at the point measured in step 9, the fitted form is Q... A = f Q,A The formula for (T), where Q A The battery capacity is measured at a reference temperature, where T is the battery temperature. The formula depends on the obtained results and can, for example, be a cubic polynomial. The limiting Q can then be calculated using the following formula. min :

[0093] [Formula 7]

[0094] Also needed is that at the points measured in step 4, the fitted form is Q. B = f Q,B The formula for (T), where Q B The battery capacity is determined at the test temperature, where T is the battery temperature. The formula depends on the obtained results and can, for example, be a cubic polynomial. Finally, the limiting Q can be calculated using the following formula. max :

[0095] [Formula 8]

[0096] Once the battery capacity has been obtained (e.g., using the first or second method described above), the intermediate available state of charge (SOC) expressed in Ah can be calculated using the following formula. Disp1 :

[0097] [Formula 9]

[0098] in:

[0099] - The state of charge is expressed in Ah.

[0100] - Q min (T) represents the lower limit of battery capacity expressed in Ah, which is a function of temperature T, i.e., corresponding to... Figure 2 Define the line in region 3.

[0101] Once the battery capacity is known, the intermediate available state of charge (SOC) can be calculated as a percentage using the following formula. Disp1 :

[0102] [Formula 10]

[0103] in:

[0104] - Q max (T) is the upper limit of battery capacity expressed in Ah, which is a function of temperature T, i.e., corresponding to... Figure 2 Define the line of region 1 in the middle.

[0105] In an example consistent with the previous one, the first intermediate state of charge (SOC) is obtained. Disp1 Includes the following steps:

[0106] - Measure the current delivered by the battery;

[0107] - Measure the battery temperature;

[0108] - The total charge accumulated in the battery at the current moment is calculated using the coulomb method, which is a function of the total charge accumulated in the battery at the previous moment and a function of the measured current, through electronic processing and control systems.

[0109] - Calculate the stored state of charge, which is equal to the total charge accumulated in the battery at the current moment divided by the maximum total charge that can be accumulated in the battery;

[0110] - Calculate available charge based on the difference between the following two:

[0111] - The total charge currently accumulating in the battery; and

[0112] - Non-retrievable charge, which cannot be extracted from the battery at a given battery temperature, is determined at least based on the measured temperature and battery operating characteristics stored in the memory of the electronic processing and control system.

[0113] - Calculate the first intermediate available state of charge (SOC) Disp1It is equal to the available charge divided by the maximum available charge, which is equal to the difference between the following two: on the one hand, the maximum achievable charge that can be accumulated when the battery is charged at the stated temperature, and on the other hand, the unretrievable charge.

[0114] In an example consistent with the previous one, the battery is at rest and the initial state of charge (SOC) is determined using the coulomb method. stock At that time, the first intermediate usable state of charge (SOC) is obtained. Disp1 It also includes measuring the open-circuit battery voltage (OCV) to determine the initial state of charge (SOC). stock The steps. In fact, determining the initial stored SOC can be used to calculate the first intermediate available state of charge (SOC). Disp1 Second intermediate available state of charge (SOC) Disp2 .

[0115] In an example consistent with the previous one, the first intermediate available state of charge (SOC) is... Disp1 It was obtained by implementing the method described in patent application FR3126812A1.

[0116] The second step 120 of method 100 includes obtaining a second intermediate available state of charge (SOC). Disp2 Second intermediate state of charge (SOC) Disp2 It is obtained based on the stored state of charge, the first instantaneous voltage, the instantaneous open-circuit battery voltage, and the minimum permissible voltage, which is a value predetermined by the design and is related to the battery design.

[0117] In one example, this can be based on the intermediate available state of charge (SOC) of the battery. Disp2 The mapping of the open-circuit battery voltage (OCV) as a function of battery temperature is used to obtain the second intermediate available state of charge (SOC) of the battery, expressed in Ah. Disp2 This mapping can be deterministic or existing, as it can also be used to calculate the stored state of charge (SOC). stock In this example, the second intermediate available state of charge (SOC), expressed as Ah, is... Disp2 The following formula can be used to calculate:

[0118] [Formula 11]

[0119] Alternatively, a second intermediate state of charge (SOC) expressed as a percentage relative to the battery reference capacity. Disp2 The following formula can be used to calculate:

[0120] [Formula 12]

[0121] in:

[0122] - This is the battery's reference capacity.

[0123] A battery reference capacity can be obtained by fully discharging the battery at a reference temperature (e.g., 25°C) and a reference current (e.g., C / 2). It can also be obtained relative to the battery's maximum capacity limit. To express the second intermediate available state of charge (SOC) of the battery Disp2 .

[0124] In an example advantageously compatible with the foregoing example, a second intermediate available state of charge (SOC) of 120 is obtained. Disp2 Includes the following steps:

[0125] - Determine the stored state of charge;

[0126] - Measure the battery temperature;

[0127] - The instantaneous open-circuit battery voltage is determined based on the mapping of the instantaneous open-circuit battery voltage as a function of the stored state of charge and battery temperature.

[0128] - Measure the first instantaneous voltage across the battery terminals;

[0129] - Determine the second available intermediate state of charge (SOC) based on the stored state of charge, the first instantaneous voltage, the instantaneous open-circuit battery voltage, and the minimum permissible voltage. Disp2 The minimum allowable voltage is a value predetermined by the design.

[0130] The third step 130 of method 100 includes measuring the second instantaneous voltage U across the battery terminals using any standard means typically used for this purpose. cell In one example, step 130 can be performed before step 120, and the second instantaneous voltage U cell It can be used as the first instantaneous voltage to determine the second intermediate available state of charge (SOC). Disp2 Therefore, in this example, the first instantaneous voltage and the second instantaneous voltage are the same and are obtained through measurement step 130.

[0131] The fourth step 140 of method 100 includes determining the first intermediate available state of charge (SOC). Disp1 The second intermediate state of charge (SOC) is available. Disp2 and the second instantaneous voltage U of the battery measured in step 130 cell Determine the available state of charge (SOC) Disp Therefore, the second instantaneous voltage U cell Used according to the first intermediate available state of charge (SOC) Disp1Second intermediate available state of charge (SOC) Disp2 Determine the available state of charge (SOC) Disp .

[0132] In fact, the battery's second instantaneous voltage U cell The process over time and the state of charge (SOC) stored in the battery Stock The process over time can be used to determine the second instantaneous voltage U based on the battery. cell This is used to determine whether the battery's state of charge (SOC) is low, medium, or high. It's important to note that the behavior of a low SOC varies depending on operating conditions. Therefore, knowing the current SOC is not necessarily sufficient to characterize a low SOC.

[0133] Figure 4 Figure 200 illustrates an example of how the instantaneous battery voltage changes over time during battery discharge (curve 201) and the stored state of charge (SOC). Stock Example of a process changing over time (line 202). The left vertical axis corresponds to the instantaneous voltage U of the battery. cell The value of , while the right vertical axis corresponds to the battery's stored state of charge (SOC). Stock The values ​​are expressed as percentages. The horizontal axis corresponds to time expressed in minutes. Therefore, refer to... Figure 4 For example, it can be noted that the low state of charge (SOC) Stock (Designated as 203) is characterized by the instantaneous voltage U of the battery. cell The rate of decline is accelerating.

[0134] Figure 5 The illustration shows an example of the results that can be obtained using the method according to the present invention. Figure 5 It describes the available state of charge (SOC) determined using method 100. Disp Figure 300 shows the process of an example (labeled 304). Curves 301 and 302 represent the first intermediate available state of charge (SOC), respectively. Disp1 Second intermediate available state of charge (SOC) Disp2 Examples of these enable the acquisition of the available state of charge (SOC). Disp Example (labeled 304). The vertical axis on Figure 300 corresponds to the battery's available state of charge, expressed in Ah, and the horizontal axis corresponds to time, expressed in minutes. Curve 303 corresponds to the reference state of charge (SOC).

[0135] In an example compatible with the previous one, 140 available states of charge (SOC) are determined. Disp Including by the first intermediate available state of charge (SOC) Disp1 Second intermediate available state of charge (SOC) Disp2Perform a weighted summation to calculate the available state of charge (SOC). Disp Therefore, the available state of charge (SOC) can be determined using the following formula. Disp :

[0136] [Formula 13]

[0137] in:

[0138] t represents the current time.

[0139] and As a weighting factor, for example, based on the instantaneous voltage U measured in step 130. cell And that's certain.

[0140] In an example compatible with the previous one, the weighting factor and Use the following formula to determine:

[0141] [Formula 14]

[0142] [Formula 15]

[0143] An optional fifth step 150 of method 100 includes determining the available state of charge (SOC) based on the information obtained in step 140. Disp This involves modifying battery usage conditions. Such modification can be automatic, semi-automatic, or manual, requiring human intervention. In some examples, this modification of battery usage conditions may include at least one of the following actions:

[0144] - Decisions regarding aircraft maneuvers (such as landing) are made by the user;

[0145] - The system estimates the remaining charging time and remaining discharging time, thereby estimating the aircraft's flight time or the distance it can travel before the battery is fully discharged;

[0146] - Displays available state of charge (SOC) Disp ;

[0147] - The first battery that will power the system (such as a system contained within an aircraft or the aircraft itself) and its available state of charge (SOC) Disp (As determined by method 100) Replace it with its available state of charge (SOC). Disp Greater than the available state of charge (SOC) of the first battery Disp The battery;

[0148] - Shut down the available State of Charge (SOC) DispA battery-powered system (such as a system contained within an aircraft or an aircraft) as determined by method 100.

[0149] - Predict the available state of charge (SOC) Disp The remaining charge duration of the battery as determined by method 100; and

[0150] - For the available state of charge (SOC) Disp Maintenance operations are performed on identified battery-powered systems (such as systems contained within an aircraft) or aircraft.

[0151] The present invention also relates to a battery management system including means for implementing method 100. For example, the management system according to the invention may include an electronic processing and control system (also referred to as a "computer") comprising at least a processor and a memory, the electronic processing and control system being configured to execute the steps of method 100. Furthermore, optionally, the battery management system may include means for displaying the available state of charge (SOC) determined by method 100. Disp1 The apparatus includes at least one device for measuring battery temperature, at least one device for measuring voltage across battery terminals, and at least one device for measuring current flowing through the battery.

Claims

1. A method for managing the available state of charge (SOC) of a battery. Disp The method (100) includes the following computer-implemented steps: - Obtain the first intermediate available state of charge (SOC) of the battery (110). Disp1 First intermediate state of charge (SOC) Disp1 It is obtained from the battery capacity table as a function of battery temperature. The battery capacity table allows for the determination of the lower limit and upper limit of battery capacity for a set of predetermined battery temperatures. - Obtain the second intermediate available state of charge (SOC) of the battery (120). Disp2 Second intermediate state of charge (SOC) Disp2 It is obtained based on the stored state of charge, the first instantaneous voltage, the instantaneous open-circuit battery voltage, and the predetermined minimum permissible voltage. - Measure the second instantaneous voltage U across the (130) battery terminals. cell ,as well as - Based on the first intermediate available state of charge (SOC) Disp1 The second intermediate state of charge (SOC) is available. Disp2 And the measurement of the second instantaneous voltage U of (130) cell To determine the (140) available state of charge (SOC) of the battery. Disp .

2. The method (100) according to the preceding claim, wherein the available state of charge (SOC) is determined (140). Disp Including the first intermediate available state of charge (SOC) Disp1 Second intermediate available state of charge (SOC) Disp2 The weighted summation, the weights of which depend on the second instantaneous voltage U measured (130). cell .

3. The method (100) according to the preceding claim, wherein the weighted summation is calculated as follows: in: - t represents the current time. - ， - ， - A predetermined minimum voltage to ensure battery integrity, and - The predetermined maximum voltage to ensure battery integrity.

4. The method (100) according to any one of the preceding claims, wherein (110) a first usable intermediate state of charge (SOC) is obtained. Disp1 Includes the following steps: - Measure the current delivered by the battery. - Measure the battery temperature. - Through electronic processing and control systems, the total charge accumulated in the battery at the current moment is calculated based on the total charge accumulated in the battery at previous times and as a function of the measured current. - Calculate the stored state of charge, which is equal to the total charge currently accumulating in the battery divided by the maximum total charge that can accumulate in the battery. - Calculate available charge based on the difference between the following two: o The total charge currently accumulated in the battery, and o Unextractable charge, which cannot be extracted from the battery at a given battery temperature, is determined as a function of at least the measured temperature, based on the battery operating characteristics stored in the memory of the electronic processing and control system; - Calculate the first intermediate available state of charge (SOC) Disp1 It is equal to the available charge divided by the maximum available charge, which is equal to the difference between the following two: on the one hand, the maximum achievable charge that can be accumulated in the battery when the battery is charged at the stated temperature, and on the other hand, the unretrievable charge.

5. The method (100) according to any one of the preceding claims, wherein a second intermediate usable state of charge (SOC) is obtained (120). Disp2 Includes the following steps: - Determine the stored state of charge; - Measure the battery temperature; - The instantaneous open-circuit battery voltage is determined based on the mapping of the instantaneous open-circuit battery voltage as a function of the stored state of charge and battery temperature. - Measure the first instantaneous voltage across the battery terminals; - Determine the second intermediate usable state of charge (SOC) based on the stored state of charge, the first instantaneous voltage, the instantaneous open-circuit battery voltage, and the minimum permissible voltage. Disp2 The minimum permissible voltage is a data predetermined in the design.

6. The method (100) according to any one of the preceding claims further includes, based on the determined (140) available state of charge (SOC). Disp To modify the (150) battery operating conditions.

7. A battery management system comprising a processing unit configured to implement the method of any one of the preceding claims.

8. An aircraft comprising a battery and a battery management system according to the preceding claims.

9. A computer program comprising instructions that, when executed by a computer, cause the computer to perform the method according to any one of claims 1 to 6.

10. A non-transient computer-readable data medium having a computer program as described in claim 9 recorded thereon.

Images