Control of the target charging voltage of a rechargeable electric battery for motor vehicles

Description

[0001] The technical context of the present invention is that of managing a rechargeable electric battery in a motor vehicle. The present invention finds a particularly advantageous application in the energy management of a rechargeable electric battery for internal combustion, hybrid, or electric vehicles, such as, for example, a lithium-ion type energy storage device configured to deliver a direct current at a voltage of 12 volts.

[0002] The use of such rechargeable electric batteries in the automotive sector is becoming increasingly widespread, particularly for managing connected vehicle components, whether these components are involved in managing vehicle driving phases or are implemented for user comfort. These rechargeable electric batteries offer advantages, notably in terms of weight and energy density. However, it is essential to ensure that the voltage limits within which they operate guarantee their safe use while maintaining their performance.

[0003] We also know from patent document EP-A1-2982850 a method according to the preamble of claim 1.

[0004] The present invention aims to propose a new solution for managing the state of charge of a rechargeable electric battery as just mentioned, depending on the use of such an electric battery.

[0005] Another objective of the invention is to improve the performance associated with the use of such an electric battery.

[0006] Another objective of the invention is to improve the electrical safety of a low-voltage network of a motor vehicle powered by such an electric battery.

[0007] According to a first aspect, the invention relates to a method for managing a target charging voltage setpoint for a rechargeable electric vehicle battery, the method comprising the following steps: a step of defining a target state of charge of the rechargeable electric battery, a step of determining a target charging voltage of the rechargeable electric battery as a function of the target state of charge of said rechargeable electric battery, a step of securing the target charging voltage of the rechargeable electric battery, leading to defining a secure charging voltage of said rechargeable electric battery as a function of the target charging voltage, a step of defining a target charging voltage setpoint of the rechargeable electric battery.

[0008] The invention applies exclusively to rechargeable electric batteries of the lithium-ion type.

[0009] The target state of charge of a rechargeable electric battery represents the amount of energy that must be stored in it to ensure its operation under the desired conditions. The target state of charge therefore depends on the vehicle's configuration and its energy requirements. In particular, when the vehicle is equipped with an automatic start / stop function, such as those known as "Stop and Start," its energy requirements differ depending on whether this function is activated or not.

[0010] Indeed, in the event that such a feature is inactive, the vehicle's energy needs may be limited, for example, to the needs related, when the vehicle is stopped, to starting and / or implementing other features such as, for example, connected features, as well as the needs related to the durability of the rechargeable battery.

[0011] In the event that such an automatic start / stop function is active, the aforementioned target state of charge must take into account the various amounts of energy required to ensure the vehicle's operation during the different successive phases of this function's implementation. These various amounts of energy include, firstly, the energy requirements related to the automatic stop phase, secondly, the amount of energy consumed by the vehicle during the implementation of this automatic stop, and finally, the amount of energy required to perform an automatic start phase following the automatic stop phase, while maintaining sufficient energy for the implementation of one or more other successive start / stop phases in a manner that is satisfactory and convenient for the vehicle user.

[0012] In cases where an automatic start / stop function of the motor vehicle is active, the method according to the invention therefore provides, in particular, that the target state of charge of the rechargeable electric battery is determined based on: of a target state of charge enabling the automatic stop-start functionality, and an estimate of the electrical consumption of the motor vehicle when stopped during a reference period.

[0013] Advantageously, the reference period includes the period during which the vehicle is in the automatic shutdown configuration. For example, this reference period could also include a period of automatic vehicle restart following an automatic shutdown period.

[0014] It follows from the above that, in such a vehicle, the method according to the invention also provides that the step of fixing the target state of charge includes a step of determining an energy margin of the rechargeable electric battery necessary to achieve the automatic stop-start functionality of the motor vehicle and to provide sufficient electrical energy for the estimated electrical consumption of the stopped motor vehicle.

[0015] Advantageously, this energy margin is determined from a mapping of the state of charge of the rechargeable electric battery as a function of its temperature and an estimate of the electrical consumption of the vehicle stopped during the reference period.

[0016] The target state of charge also takes into account the temperature of the rechargeable battery. This temperature can, for example, be determined by a rechargeable battery management device configured to communicate this information to a battery control unit.

[0017] The target state of charge can therefore be determined once the temperature of the rechargeable electric battery and the vehicle's energy requirements are known, based on the vehicle's configuration. This determination can be made by calculation and / or using previously established rechargeable electric battery maps.

[0018] The target charging voltage of the rechargeable electric battery is to be understood here as the voltage to be applied to its terminals to charge it in order to reach the previously defined target state of charge.

[0019] More specifically, the method according to the invention provides that the target charging voltage is defined in such a way that it allows, on the one hand, the discharge of the battery when its state of charge is greater than the aforementioned target state of charge, on the other hand, the charging of the battery when its state of charge is less than the previously mentioned target state of charge, and, finally, the maintenance of the charge of the battery at the level of the target state of charge once this is reached.

[0020] In other words, the invention therefore proposes to adjust and control the charging voltage of the rechargeable electric battery in order to maintain a predetermined charge level of the latter, advantageously the level of the previously defined target state of charge or, more precisely, a level as close as possible to this target state of charge.

[0021] To achieve this, the step of determining the target charging voltage advantageously includes a step of determining the open-circuit voltage across the terminals of the rechargeable battery. This open-circuit voltage is defined, in particular, based on the temperature of the rechargeable battery, and it corresponds to a given state of charge at a predefined temperature. Such information is, for example, available from suppliers of similar rechargeable batteries in the form of charts defined for different temperatures and different states of charge of the battery.

[0022] The step of determining the target charging voltage also includes a step of defining an additional voltage to be applied to the terminals of the rechargeable electric battery, the additional voltage being determined from a temperature and a state of charge of the rechargeable electric battery, the target charging voltage being determined by the sum of the previously defined open-circuit voltage and the aforementioned additional voltage.

[0023] Advantageously, the step of securing the target charging voltage of the rechargeable electric battery includes a verification of the target charging voltage against a maximum threshold voltage and a minimum threshold voltage. The target charging voltage of the rechargeable electric battery must be between the maximum and minimum threshold voltages. The target charging voltage must be located between these two voltage thresholds to guarantee, on the one hand, the correct and safe operation of the rechargeable electric battery and, on the other hand, its durability.

[0024] Advantageously, during the step of securing the target charging voltage, the secured charging voltage is equal to: the target charging voltage if the target charging voltage is between the aforementioned minimum threshold voltage or maximum threshold voltage, or if the target charging voltage is equal to the minimum threshold voltage or the maximum threshold voltage, the minimum threshold voltage if the target charging voltage is strictly less than the minimum threshold voltage, the maximum threshold voltage if the target charging voltage is strictly greater than the maximum threshold voltage.

[0025] According to an example of implementation of the method according to the invention, the step of securing the target charging voltage of the rechargeable electric battery includes a step of verifying that an instantaneous variation of the charging voltage is between a minimum voltage gradient and a maximum voltage gradient.

[0026] In other words, according to this example, the method according to the invention involves a comparison between, on the one hand, an instantaneous variation in the charging voltage and, on the other hand, a minimum and a maximum gradient of this voltage. This allows, in particular, for the consideration of any transient phenomena that may occur during the charging and / or operation of the rechargeable electric battery, for example, as a result of transient phenomena occurring during vehicle operation.

[0027] The target charging voltage of the rechargeable electric battery is understood here as the charging voltage actually applied to that battery at a given instant, for example, measured at the terminals of the rechargeable electric battery or at the terminals of an electrical power source configured to charge the rechargeable electric battery, such as, but not limited to, an alternator or a vehicle's current converter. The instantaneous change in charging voltage is understood as the difference between the previously defined target charging voltage and the charging voltage actually measured at a given instant.

[0028] The target charging voltage setpoint for the rechargeable electric battery is then defined based on the safe charging voltage.

[0029] Advantageously, the method according to the invention also includes a step for regulating the instantaneous variation of the target charging voltage of the rechargeable electric battery, such that: If the instantaneous change in charging voltage is strictly greater than the previously defined maximum voltage gradient, then the charging voltage applied to the rechargeable electric battery is reduced so that the instantaneous change in charging voltage is less than or equal to the maximum voltage gradient, and if the instantaneous change in charging voltage is strictly less than the minimum voltage gradient, then the charging voltage of the electric battery is increased so that the instantaneous change in charging voltage is greater than or equal to the minimum voltage gradient.

[0030] The process according to the invention also advantageously presents one or more of the following characteristics, taken separately or in combination: The method includes a step for correcting the target charging voltage applied to the terminals of the rechargeable battery, based on the safe charging voltage and a value of the charging voltage measured at the terminals of the rechargeable battery. This step implements proportional-integral-derivative regulation based on the difference between the safe charging voltage and a value of the charging voltage measured at the terminals of the rechargeable battery, or the initial corrective voltage variation, in order to calculate a correction factor for said bias voltage. More specifically, if the initial corrective voltage variation is between a minimum and a maximum value, the charging voltage correction factor is equal to the initial corrective voltage variation.If the initial correction voltage variation is strictly less than the minimum value, the charging voltage correction factor is equal to the aforementioned minimum value. If the initial correction voltage variation is strictly greater than the maximum value, the charging voltage correction factor is equal to the aforementioned maximum value. The target charging voltage setpoint for the electric battery is determined by the safe charging voltage to which the previously defined correction factor is applied. Advantageously, the method includes a subsequent step of driving a power generator electrically coupled to the rechargeable electric battery, the power generator being configured to bias the rechargeable electric battery according to the aforementioned target charging voltage setpoint.

[0031] The invention thus achieves continuous control and adjustment of the charging voltage applied to the terminals of a rechargeable electric battery to ensure its optimal operation. This limits any unnecessary energy consumption both within the rechargeable electric battery and within an electrically coupled power generator used to recharge the battery, while guaranteeing the operating performance and durability of said rechargeable electric battery.

[0032] According to a second aspect, the invention relates to a control unit for an electric battery of a motor vehicle, the control unit being configured to implement the method as just described.

[0033] According to a third aspect, the invention relates to a motor vehicle comprising: an on-board network supplied with electrical energy by a power group comprising a rechargeable electric battery as previously mentioned, an electric generator electrically coupled to the rechargeable electric battery and configured to be able to recharge said rechargeable electric battery, a control unit as previously mentioned, connected to the rechargeable electric battery and the electric generator, so that the electric generator drives a charging voltage of the rechargeable electric battery according to a target charging voltage setpoint determined by the control unit.

[0034] Other features and advantages of the invention will become apparent from the following description on the one hand, and from the illustrative and non-limiting examples of embodiments given with reference to the attached schematic drawings on the other hand, in which: [ Fig.1 [ ] schematically illustrates a control unit according to the invention, as well as a control and management system for an electric battery to which the control unit is associated. Fig.2 ] schematically illustrates the process according to the invention.

[0035] Of course, the features, variants, and different embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive. In particular, variants of the invention may include only a selection of features, described hereafter in isolation from the other described features, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from prior art.

[0036] In particular, all the variants and embodiments described can be combined with each other if there are no technical obstacles to this combination.

[0037] In the figures, elements common to several figures retain the same reference.

[0038] There Figure 1 The diagram schematically illustrates a rechargeable electric battery 1 of a motor vehicle and a control unit 2 for the rechargeable electric battery 1 as provided for in the invention. According to a preferred, but not exclusive, example, the rechargeable electric battery 1 is of the 12-volt storage type, that is, it is configured to store electrical energy and to deliver this energy in the form of a direct current at a voltage of 12 volts. By way of non-limiting example, such a voltage is typically that used in a motor vehicle during vehicle start-up phases or for the implementation of automatic vehicle start / stop functionalities such as those known as "Stop and Start".

[0039] Control unit 2 is specifically configured to implement the process according to the invention as described above.

[0040] To achieve this, the control unit 2 is configured to determine a target state of charge 10 for the rechargeable electric battery 1. As previously stated, the target state of charge 10 represents the amount of energy that must be stored in the rechargeable electric battery 1 to ensure both its performance and its durability. The target state of charge 10 is determined based on a temperature 11 of the rechargeable electric battery 1 and the energy requirements 12 of the motor vehicle equipped with the rechargeable electric battery 1.

[0041] In one example, the aforementioned temperature 11 is measured by a temperature sensor installed on the electric battery 1, and the control unit 2 includes a receiver configured to receive and store the temperature information measured by the aforementioned sensor. In another example, the temperature 11 of the electric battery 1 is measured in a battery management device 3 and transmitted to the control unit 2, which advantageously includes means, not shown in the diagram. Figure 1 , to communicate with the electric battery management device 1.

[0042] The vehicle's energy requirements 12 are determined based on the activation status of various vehicle features and, in particular, based on the activation status of automatic stop / start features such as those known under the Anglo-Saxon name "Stop and Start".

[0043] More specifically, in the case of a vehicle equipped with an automatic stop / start function as described above, and in the case where this function is active, the target state of charge advantageously takes into account, on the one hand, the energy requirements 120 necessary to carry out an automatic stop of the vehicle, on the other hand, the energy requirements 121 necessary for the operation of the vehicle during the automatic stop phase, and finally, the energy requirements 122 necessary to carry out an automatic restart of the vehicle following the automatic stop phase.In other words, in this case, the vehicle's energy requirements 12, taken into account for determining the target state of charge 10, include a quantity of energy 125, also referred to above as the energy margin, necessary both for the automatic shutdown and automatic startup, and for the vehicle's electrical consumption when it is stopped. The determination of the aforementioned energy requirements 12 is therefore based, in this case, on an estimate of the vehicle's electrical consumption during its automatic shutdown period.

[0044] In the case of a vehicle not equipped with an automatic start / stop function, or where this function is not active, the target state of charge 10 can, for example, be set to a predefined percentage of the rechargeable electric battery's nominal charging capacity. For example, this percentage could be between 80 and 90% of the aforementioned nominal capacity, for example 85%.

[0045] The vehicle's energy requirements 12 are, for example, determined within a central vehicle control and steering unit 4 with which the control unit 2 is configured to communicate. They can be established on the basis of measurements of the vehicle's electrical consumption during different operating phases, as well as on the basis of calibration curves or maps previously created.

[0046] The control unit 2 is also configured to determine a target charging voltage 13 for the rechargeable electric battery 1. The target charging voltage 13 represents the voltage to be applied to the terminals of the rechargeable electric battery 1, for example, by means of an electrical generator 5 such as an alternator or a DC-DC converter of the vehicle type, to recharge the rechargeable electric battery 1 and reach the previously defined target state of charge 10. The target charging voltage 13 is determined, in particular, within the control unit 2, based on the previously defined target state of charge 10 and the temperature 11 of the rechargeable electric battery 1.

[0047] Advantageously, the control unit 2 is also configured to communicate with an electrical producer 5 as previously defined, in order, on the one hand, to control this electrical producer 5 so that it applies to the terminals of the rechargeable electric battery 1 the aforementioned target charging voltage setpoint 50, determined by the control unit 2, and, on the other hand, to receive from the electrical producer 5 information relating to a charging voltage 51 actually applied to the terminals of the rechargeable electric battery 1. The target charging voltage setpoint 50 is determined on the basis of the target state of charge 10 and the target charging voltage 13 previously defined.

[0048] More specifically, the control unit 2 is advantageously configured to determine, from the previously defined temperature 11 and the state of charge of the rechargeable electric battery 1, for example known by the previously mentioned system 3, an open-circuit voltage 14 of the rechargeable electric battery 1. The open-circuit voltage 14 is, for example, defined from a voltage map of similar rechargeable electric batteries, established beforehand, for example by suppliers of this type of battery, for different temperatures and different states of charge of the rechargeable electric battery 1.

[0049] Advantageously, the control unit 2 is also configured to define an additional voltage 15 to be applied to the terminals of the rechargeable electric battery 1 and to command the power generator 5 to apply this additional voltage 15 to the terminals of the rechargeable electric battery 1 in addition to the aforementioned open-circuit voltage 14 in order to reach the previously defined target charging voltage 13. The target charging voltage 13 is therefore obtained by the sum of the open-circuit voltage 14 and the additional voltage 15.

[0050] It is necessary to understand here that the additional voltage 15 is defined, at a given instant t, as a function of the target state of charge 10 previously defined and of a state of charge 16 of the rechargeable electric battery 1, for example measured by the management system 3 of this battery at the aforementioned instant t.

[0051] More specifically, the additional voltage 15 is determined in such a way that: If the state of charge 16 is greater than the target state of charge 10, that is, if the amount of energy stored in the rechargeable battery 1 is greater than the amount of energy defined by the target state of charge 10, applying the additional voltage 15 leads to a discharge of the rechargeable battery 1. If the state of charge 16 is less than the target state of charge 10, that is, if the amount of energy stored in the rechargeable battery 1 is less than the amount of energy defined by the target state of charge 10, applying the additional voltage 15 leads to a charge of the rechargeable battery 1. If the state of charge 16 is equal to the target state of charge 10, that is, if the amount of energy stored in the rechargeable battery 1 is equal to the amount of energy defined by the target state of charge 10, applying the additional voltage 15 leads to maintaining the charge of the rechargeable electric battery 1.

[0052] This makes it possible in particular to avoid any excessive stress on both the rechargeable electric battery 1 and the electric producer 5, and thus to increase the life of these elements while ensuring that the state of charge of the rechargeable electric battery 1 is as close as possible to the target state of charge 10.

[0053] The control unit 2 is therefore configured to compare a state of charge 16 of the rechargeable electric battery 1 at a given time t, for example known from the management system 3 previously mentioned, with the target state of charge 10.

[0054] For better control of the charging of the rechargeable electric battery 1, the control unit 2 is configured to calculate, from the previously defined target charging voltage 13, a safe charging voltage 17, advantageously between a minimum threshold voltage 170 and a maximum threshold voltage 171. The safe charging voltage 17 is therefore defined on the basis of operating limits of the rechargeable electric battery 1, which are themselves known, for example, transmitted to the control unit 2 by the rechargeable electric battery 1 management system 3.

[0055] The control unit 2 is also advantageously configured to compare the previously defined target charging voltage 13 with an actual charging voltage 51 applied to the terminals of the rechargeable electric battery 1 at a given time t. The actual charging voltage 51 is, for example, measured by the power generator 5 and / or by the battery management system 3, and communicated to the control unit 2 configured to communicate with these components.

[0056] More specifically, the control unit 2 includes means for calculating an instantaneous variation 52 of the charging voltage at the terminals of the rechargeable electric battery 1. The instantaneous voltage variation 52 is, for example, defined as the difference between the target charging voltage 13 and the charging voltage 51 actually applied to the terminals of the rechargeable electric battery 1 at a given time t.

[0057] According to the invention, the control unit 2 includes means for regulating the instantaneous voltage variation 52. This makes it possible, in particular, to prevent any excessive overvoltage at the terminals of the rechargeable electric battery, for example, resulting from a transient increase in current demand. In other words, the aforementioned regulation makes it possible to limit the effects, on the rechargeable electric battery 1, on the one hand, and on the components that this battery powers within the vehicle, on the other hand, of transient phenomena that could lead to a brief but significant increase in the vehicle's energy requirements. This regulation therefore makes it possible to improve the lifespan of the rechargeable electric battery 1 and the components that it powers.

[0058] According to one example, the control unit 2 includes means for comparing the instantaneous voltage variation 52 previously defined with, on the one hand, a minimum value 520 of voltage gradient, and, on the other hand, a maximum value 521 of voltage gradient, such that, depending on the result of this comparison, the target charging voltage setpoint 50 transmitted by the control unit 2 to the power producer 5 is increased or decreased.

[0059] More specifically, the invention provides that the target charging voltage setpoint 50 is increased if the instantaneous voltage variation 52 is less than the minimum voltage gradient value 520, and that the target charging voltage setpoint 50 is decreased if the instantaneous voltage variation 52 is greater than the maximum voltage gradient value 521. Regulating the instantaneous voltage variation 52 thus allows for a gradual modification of the target charging voltage setpoint 50 applied to the terminals of the rechargeable electric battery 1, without significant abrupt changes, thereby preserving the lifespan of the rechargeable electric battery 1 and that of the vehicle components powered by it.

[0060] According to the invention, the control unit 2 includes calculation means configured to correct the target charging voltage setpoint 50 transmitted to the power generator 5 based on the safe charging voltage 17 and the charging voltage 51 actually applied to the terminals of the electric battery 1. In this example, the control unit 2 is configured to calculate a correction factor 55 based on the difference between the safe charging voltage 17 and the charging voltage 51 actually applied to the terminals of the battery 1, and to apply this correction factor 55 to the aforementioned target charging voltage setpoint 50. In various examples, the correction factor 55 can be added to the target charging voltage setpoint 50, or the correction factor 55 can be in the form of a multiplier applied to the target charging voltage setpoint 50.

[0061] There Figure 2 schematically shows the process according to the invention and its various stages in the case of a vehicle equipped with an automatic stop / start function.

[0062] We find in particular on the Figure 2 schematically represented, the control unit 2 and the electrical producer 5 previously defined.

[0063] In a first step 100 of the process according to the invention, the target state of charge 10 of the electric battery 1 is determined by the control unit 2 as previously described.

[0064] In a second step 200 of the process according to the invention, the target charging voltage 13 is determined by the control unit 2 as previously described. As previously described, the step 200 of determining the target charging voltage 13 advantageously comprises a substep 201 of defining the previously defined open-circuit voltage 14 and a substep 202 of defining the previously described additional voltage 15, the target charging voltage 13 being defined as the sum of the open-circuit voltage 14 and the additional voltage 15.

[0065] In a third step 300 of the process according to the invention, the safe charging voltage 17 is calculated by the control unit 2.

[0066] To do this, as described previously, the third step 300 of the process includes a substep 301 of comparing the target charging voltage 13 with a minimum threshold voltage 170 and a maximum threshold voltage 171 previously defined.

[0067] If the target charging voltage 13 is between the minimum threshold voltage 170 and the maximum threshold voltage 171, or if the target charging voltage 13 is equal to one of these threshold voltages, the method according to the invention provides that the safe charging voltage 17 is equal to the target charging voltage 13. If the target charging voltage 13 is strictly less than the minimum threshold voltage 170, the method according to the invention provides that the safe charging voltage 17 is equal to the minimum threshold voltage 170. If the target charging voltage 13 is strictly greater than the maximum threshold voltage 171, the method according to the invention provides that the safe charging voltage 17 is equal to the maximum threshold voltage 171.

[0068] By way of non-exclusive example, for a rechargeable electric battery 1 configured to deliver a direct current at a voltage of 12 volts, the minimum threshold voltage 170 could be around 10 volts and the maximum threshold voltage could be around 14 volts. These threshold voltages represent the operating limits of the rechargeable electric battery 1, defined to guarantee optimal lifespan and performance throughout its service life. The method according to the invention therefore ensures that the safe charging voltage 17, defined by the control unit 2, remains compatible with the aforementioned operating limits.

[0069] In a fourth step 400 of the process according to the invention, the previously defined target charging voltage setpoint 50 is determined within the control unit 2 on the basis of the target state of charge 10 and the safe charging voltage 17, and it is transmitted to the previously mentioned power producer 5 to be applied to the terminals of the rechargeable electric battery 1.

[0070] With reference to the above, the fourth step 400 of the method according to the invention includes a substep 401 of calculating the instantaneous variation of charging voltage 52 previously defined, and a substep 402 of comparing this instantaneous variation of charging voltage 52 with, respectively, a minimum voltage gradient 520 and a maximum voltage gradient 521 previously mentioned.

[0071] If the instantaneous variation in charging voltage 52 is strictly greater than the maximum voltage gradient 521, the method according to the invention provides that the target charging voltage setpoint 50 is reduced. If the variation in charging voltage 52 is strictly less than the minimum voltage gradient 520, the method according to the invention provides that the target charging voltage setpoint 50 is increased. The method according to the invention advantageously provides for the implementation of a plurality of substeps 401 and 402 as described above, until the instantaneous variation in charging voltage 52 is between the minimum voltage gradient 520 and the maximum voltage gradient 521, or equal to one of these two values. The method according to the invention thus provides a control loop for the instantaneous variation in charging voltage 52.

[0072] It must be understood here that the objective of this regulation loop is that the target charging voltage setpoint 50 is reached at the terminals of the electric battery 1 without too abrupt a variation of the charging voltage 51 actually measured at the terminals of said battery, which could lead to damage to both the battery and some of the components that it electrically powers.

[0073] By way of non-limiting example, the operating requirements of a rechargeable electric battery 1 configured to deliver direct current at a voltage of 12 volts may limit to + / - 2 volts the voltage variation applied over a predefined time interval to the terminals of this battery in order to protect both the battery and the vehicle components it powers. The aforementioned regulation loop smooths the curve of the charging voltage 51 actually applied to the terminals of such a battery to reach the target charging voltage setpoint 50.

[0074] Additionally, the fourth step 400 of the process according to the invention includes a substep 403, not shown in the Figure 2, correction of the target charging voltage setpoint 50 as a function of the previously defined safe charging voltage 17 and the charging voltage 51 actually measured at the terminals of the rechargeable electric battery 1. This substep 403 includes a calculation operation, within the control unit 2, of the correction factor 55 previously described and of the deviation 18, also referred to above as the initial corrective voltage variation, between the safe charging voltage 17 and the charging voltage 51 actually measured at the terminals of the rechargeable electric battery 1. Substep 403 advantageously also includes an operation of comparing the initial corrective voltage variation 18 with a previously defined minimum threshold value and a maximum threshold value.

[0075] If the initial corrective voltage variation 18 is between the aforementioned minimum and maximum threshold values, the method according to the invention provides that the correction factor 55 is equal to the initial corrective voltage variation 18. If the initial corrective voltage variation 18 is strictly less than the aforementioned minimum threshold value, the method according to the invention provides that the correction factor 55 is equal to this minimum threshold value. If the initial corrective voltage variation 18 is strictly greater than the aforementioned maximum threshold value, the method according to the invention provides that the correction factor 55 is equal to this maximum threshold value. Through a series of substeps 403, the method according to the invention performs a progressive adjustment loop of the charging voltage 51 actually measured at the terminals of the rechargeable electric battery 1 with respect to the target charging voltage setpoint 50.

[0076] In summary, the invention makes it possible to define, based on a target state of charge 10 and a target safe charging voltage 17, a target charging voltage setpoint 50 to be applied to the terminals of a rechargeable electric battery 1 so that the latter can meet the energy requirements 12 of the vehicle. By regulating, on the one hand, the charging voltage 51 actually applied to the terminals of the rechargeable electric battery 1 and, on the other hand, the instantaneous variation of charging voltage 52 between the safe charging voltage 17 and the charging voltage 51 actually measured at the terminals of the rechargeable electric battery 1, the method according to the invention makes it possible for the aforementioned target charging voltage setpoint 50 to be reached under optimal conditions of lifespan and operation of the rechargeable electric battery 1.

[0077] Of course, the invention is not limited to the examples just described, and many modifications can be made to these examples without departing from the scope of the invention, which is defined by the appended claims. In particular, the various features and embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive. Specifically, all the variants and embodiments described above are combinable. All these variants and embodiments form part of the invention to the extent that they fall within the scope of the appended claims.

Claims

1. Method for managing a target recharge voltage setpoint (50) of a rechargeable electric battery (1) of a motor vehicle, the method comprising the following steps: - a step (100) of defining a target state of charge (10) of the rechargeable electric battery (1), - a step (200) of determining a target recharge voltage (13) of the rechargeable electric battery (1) as a function of the target state of charge (10) of said rechargeable electric battery (1), the target recharge voltage (13) being defined as the voltage to be applied to the terminals of the rechargeable electric battery (1) to recharge it so as to reach the target state of charge (10) previously defined, characterized in that it further comprises: - a step (300) of securing the target recharge voltage (13) of the electric battery, leading to defining a safe recharge voltage (17) of said rechargeable electric battery (1) as a function of the target recharge voltage (13), the safe recharge voltage (17) being equal to: - the target recharge voltage (13) if the target recharge voltage (13) is between a minimum threshold voltage (170) and a threshold voltage maximum (171), or if the target recharge voltage (13) is equal to the minimum threshold voltage (170) or the maximum threshold voltage (171), - the minimum threshold voltage (170) if the target recharge voltage (13) is strictly lower than the minimum threshold voltage (170), - the maximum threshold voltage (171) if the target recharge voltage (13) is strictly greater than the maximum threshold voltage (171), - a step (400) of defining a target recharge voltage setpoint (50) of the rechargeable electric battery (1), the target recharge voltage setpoint (50) of the rechargeable electric battery (1) being defined on the basis of the secure recharge voltage (17), - a step of correcting the target recharge voltage (13) applied to the terminals of the rechargeable electric battery (1) from a secure recharge voltage (17) and a value of the recharge voltage (51) measured at the terminals of the rechargeable electric battery (1).

2. Method according to the preceding claim, in which, in the case where an automatic stop-start functionality of the motor vehicle is active, then the target state of charge (10) of the rechargeable electric battery (1) is determined as a function of: - a target state of charge allowing the shutdown functionality to be achieved-automatic start, and - an estimate of the electrical consumption of the motor vehicle stopped during a reference period.

3. A method according to any one of the claims previous, in which the step (100) of determining the target state of charge (10) comprises a step of determining an energy margin of the rechargeable electric battery (1) necessary for achieving the automatic stop-start functionality of the motor vehicle and for providing sufficient electrical energy for the electrical consumption estimated value of the stopped motor vehicle.

4. Method according to any one of the preceding claims, in which the step (200) of determining the target recharge voltage (13) comprises a step of defining an additional voltage (15) to be applied to the terminals of the electric battery. rechargeable (1), the additional voltage (15) being determined from a temperature (11) of the rechargeable electric battery (1) and a state of charge of the rechargeable electric battery (1), the target recharge voltage (13) being determined by the sum of an open-circuit voltage (14) at the terminals of the rechargeable electric battery (1) and the additional voltage (15).

5. Method according to any one of the preceding claims, in which the step of correcting the recharge voltage (51) implements a proportional-integral-derivative type regulation from a voltage difference between the secure recharge voltage (17) and the recharge voltage value (51) measured at the terminals of the electric battery. rechargeable (1), said initial corrective voltage variation (18), in order to calculate a correction factor (55) of said recharge voltage (51).

6. Method according to the preceding claim, in which the target recharge voltage setpoint (50) of the electric battery rechargeable is determined by the safe recharge voltage (17) to which the correction factor (55) is applied.

7. Control unit (2) of an electric battery rechargeable battery (1) of a motor vehicle, the control unit (2) being configured to implement the method according to any one of the preceding claims.

8. Motor vehicle comprising: - an on-board network supplied with electrical energy by a power supply unit comprising a rechargeable electric battery (1), - an electrical producer (5) electrically coupled to the rechargeable electric battery (1) and configured to be able to recharge said rechargeable electric battery (1), - a control unit (2) according to the preceding claim, connected to the rechargeable electric battery (1) and to the electric producer (5) so that the electrical producer (5) controls a recharge voltage (51) of the rechargeable electric battery (1) according to a target recharge voltage setpoint (50) determined by the control unit.