Method of using a battery state counter

Abstract

The invention relates to a management method for managing a battery, which method performs: - a diagnosis step (E0, E1, E2, E3) for diagnosing the battery after the start of the vehicle and each time the vehicle is driven, which diagnosis provides a state among three possible states (Z1, Z2, Z3) of the battery: - the battery is able to respond to a predetermined electrical request (Z3), or - the battery is not able to respond to the predetermined electrical request (Z1), or - it is still uncertain whether the battery is able to respond to the predetermined electrical request (Z2), and, after the diagnosis step, the management method performs a fifth step (E4) consisting in incrementing by a value of 1 a first counter (C1) when the battery is not able to respond to the predetermined electrical request (Z1), or a second counter (C2) when it is still uncertain whether the battery is able to respond to the predetermined electrical request (Z2).

Description

Technical Field

[0001] This invention claims priority to French application 2012039, filed on November 24, 2020, the contents of which (text, drawings and claims) are incorporated herein by reference.

[0002] The present invention relates to a method for motor vehicles having safety features powered by an electric battery, and more specifically for vehicles that are purely electrically driven. Background Technology

[0003] "Safety function" or "safety device" is understood as a function or device designed to ensure the safety of the driver or passengers in the event of a malfunction. In this case, the malfunction is caused by the battery's inability to maintain a sufficient voltage for the safety function or device after receiving an inrush current (e.g., between 50A and 130A, especially 100A). As an example, functions or devices that require such an inrush current (e.g., electric power steering systems) or electric braking devices (e.g., service brakes, emergency brakes, brake assist systems, or anti-skid systems) may be considered.

[0004] Throughout this document, “powering on the vehicle” is understood as an action by the driver (e.g., via the ignition key, in the location usually indicated by the acronym + APC) that powers the computer in order to start the vehicle, but disables power control and keeps the vehicle stationary.

[0005] Throughout this document, “starting the vehicle” is understood as an additional action by the driver that authorizes the vehicle to move via its powertrain, thus making power control effective after the vehicle is powered on. For example, the accelerator pedal becomes active after the ignition key is switched to a starting position typically indicated by, for example, the acronym +DEM or START or READY, located at one or more latches following the power-on position.

[0006] Throughout this document, “stopping the vehicle” is understood as the opposite of an additional action that prevents the vehicle from moving, for example, by expressing the driver’s intention to leave the vehicle through the opposite actuation or de-energization of the ignition key to the energized position.

[0007] "Vehicle movement" is understood as all actions that occur between the moment the vehicle starts and the moment it stops.

[0008] A method for detecting whether the battery's capacity is less than a threshold value is known from patent document EP1207083A1. This threshold value is set to at least meet the needs of an electric power steering system or an electric braking system. For example, when the capacity is less than the threshold value, the method limits the maximum speed of the vehicle.

[0009] Unfortunately, this method presupposes that the information regarding the battery's capabilities is reliable, without taking into account any uncertainties, and does not prioritize certain measurements. Consequently, the driver's intentions are directly hampered by these measurements, which may be disproportionately or conversely insufficient, thus posing a safety risk. Summary of the Invention

[0010] The purpose of this invention is to overcome this deficiency by providing a reliable and more accurate method.

[0011] Therefore, the present invention aims to provide a method for controlling a vehicle battery, the vehicle including the battery and a control unit implementing the method, the method performing:

[0012] - Diagnostic steps for diagnosing the battery after the vehicle is started and each time the vehicle is driven.

[0013] The diagnostic provides the status of the battery among three possible states:

[0014] - The battery is capable of responding to a predetermined electrical request (sollicitation), or

[0015] - The battery is unable to respond to the predetermined electrical request, or

[0016] It remains uncertain whether the pre-determined electrical request can be responded to.

[0017] Furthermore, after the diagnostic step, the method performs a fifth step, which involves incrementing the first counter by 1 when the battery is unable to respond to the predetermined electrical request, or incrementing the second counter by 1 when it is still uncertain whether the battery can respond to the predetermined electrical request.

[0018] Therefore, the present invention is able to count the different states of the battery during continuous driving, which enables better management of alarms and / or alarm levels in proportion to the actual state of the battery, while having better accuracy. The driver is thus no longer hindered by disproportionate or conversely insufficient alarms and / or measurements.

[0019] According to an embodiment of the present invention, the fifth step resets the first counter and the second counter to zero values ​​when the battery is able to respond to a predetermined electrical request.

[0020] According to an embodiment of the present invention, after the fifth step, the method performs a sixth step, the sixth step of which emits a maximized alarm when the first counter is greater than or equal to a first predetermined threshold, or when the second counter is greater than or equal to a second predetermined threshold.

[0021] According to an embodiment of the present invention, the sixth step is to issue an intermediate alarm when the second counter is greater than or equal to a third predetermined threshold and strictly less than the second predetermined threshold, and when the first counter is strictly less than the first predetermined threshold.

[0022] According to an embodiment of the present invention, when the maximized alarm is transmitted, the method is as follows:

[0023] - Activate the stop message to attract the driver's attention, and / or

[0024] - Activate the fixed indicator light associated with the battery to prompt the driver to check the battery, and / or

[0025] - Activate power supply interruptions for electrical consumers who are pre-defined as having non-priority over other consumers, especially comfort functions in the face of safety features.

[0026] According to an embodiment of the present invention, when the intermediate alarm is transmitted, the method activates service information to attract the driver's attention, thereby encouraging the driver to at least recharge the battery. Attached Figure Description

[0027] Other features and advantages of the invention will become more apparent from the following detailed description and accompanying drawings of non-limiting specific embodiments, in which:

[0028] - Figure 1 This is a schematic diagram of an electrically traction vehicle conforming to the present invention;

[0029] - Figure 2 A simplified flowchart of a method according to an embodiment of the present invention is shown.

[0030] - Figure 3 An example of a mapping used by the method according to the present invention is shown. Detailed Implementation

[0031] It should be noted that the accompanying drawings are given by way of example and do not limit the invention. The drawings constitute schematic diagrams to facilitate understanding of the principles of the invention and are not necessarily to scale for actual application. Furthermore, in the following text, all drawings taken in combination are referred to. When referring to one or more particular drawings, these drawings should be combined with other drawings to identify the indicated reference numerals. Reference numerals for invariant elements or elements having the same function are common in all drawings and all embodiments.

[0032] Figure 1 A motor vehicle conforming to the present invention is illustrated schematically, in which the method according to the present invention is applied.

[0033] Motor vehicle 2 is of the electric traction type, such as a pure electric vehicle or a hybrid vehicle. Motor vehicle 2 includes a low-voltage battery 4, which is, for example, a lead-acid battery, but not necessarily; it can also be a lithium-ion battery. The low-voltage battery 4 supplies power to the vehicle's onboard networks (especially the dashboard, lighting and light signals, engine controller, etc.).

[0034] "Low voltage" is understood to be a voltage less than or equal to 48 volts, although it is currently typically 12 volts. The motor vehicle 2 also includes a high-voltage battery 6, which powers one or more electric traction motors of the vehicle. The voltage at the terminals of this battery can vary between 100 volts and 600 volts. A DC-DC converter ("DC" is an abbreviation for "Direct Current") 8 is electrically connected to the high-voltage battery 6 and the low-voltage battery 4, and is configured to recharge the low-voltage battery 4 based on the high-voltage battery 6. This DC-DC converter enables the high voltage of the high-voltage battery 6 to be converted into a compatible low voltage for recharging the low-voltage battery 4.

[0035] In addition to recharging the low-voltage battery 4, the converter 8 can also supply 12V power to the entire vehicle network.

[0036] In the example shown, the converter 8 is unidirectional and controlled in terms of voltage, but in variations, especially for hybrid vehicles, the converter 8 can be bidirectional and controlled in terms of either voltage or current. In the nominal case, the low-voltage battery 4 only intervenes if the converter 8 (due to its insufficiently fast dynamics) is insufficient to power the vehicle network alone or to provide the power required to activate safety functions or devices.

[0037] Always refer to Figure 1The motor vehicle 2 also includes a control unit 10 for managing the low-voltage battery 4. The low-voltage battery 4 plays a crucial role in the vehicle because it supplies power to the entire onboard network of the vehicle when the dynamics of the converter 8, as described above, are insufficient to respond quickly enough to the demands of these safety functions, such as the anti-lock braking system (ABS), electric power steering, etc. For these reasons, it is important to ensure the proper functioning of the low-voltage battery 4 before authorizing the vehicle to move above a certain speed (e.g., 30 m / h).

[0038] Therefore, multiple pre-emptive electrical requests to battery 4 (which trigger multiple successive surge currents) are a means of testing the battery 4’s true capability to provide the power required for safety functions (that is, to maintain a predetermined minimum voltage for a given surge current) by estimating parameters (e.g., the internal resistance Rint of the memory and the minimum voltage Umin reached during each of these surge currents).

[0039] exist Figure 2 In this example, the control unit 10 is an implementation component for carrying out the method according to the invention, and the control unit 10 controls, for example, the DC-DC converter 8 to implement these connected electrical requests, but other components for implementing these connected electrical requests are conceivable. These electrical request components are controlled by the control unit 10 and may include, for example, passive resistors connected at the terminals of the battery 4 via connecting components (which are themselves also controlled by the control unit 10).

[0040] Note that in the variant, only one electrical request may be implemented.

[0041] Figure 2 This is a flowchart illustrating the operating principles of the control method according to the invention, implemented, for example, by means of control unit 10.

[0042] The control unit 10 may include, for example, a battery charging status box (BECB) or a battery management system (BMS) and / or other computers, or may be configured as a dedicated control unit (or computer) that may include dedicated programs. Therefore, the control unit 10 according to the invention may be implemented as a software module (or computer (or "software")), an electronic circuit (or "hardware"), or a combination of electronic circuitry and software modules.

[0043] The control method for managing battery 4 begins with the first step E0 for diagnosing low-voltage battery 4.

[0044] The control method for controlling the battery 4 of a vehicle (including the battery 4 and the control unit 10 implementing the method) is executed as follows:

[0045] - Diagnostic steps E0, E1, E2, and E3 are used to diagnose the battery 4 after the vehicle is started and each time the vehicle is driven. This diagnosis provides a state among the three possible states Z1, Z2, and Z3 of the battery 4:

[0046] - The battery is capable of responding to a predetermined electrical request Z3, or

[0047] - The battery is unable to respond to the predetermined electrical request Z1, or

[0048] - It remains uncertain whether we can respond to the predetermined electrical request Z2.

[0049] Furthermore, after the diagnostic step, the method performs a fifth step E4, which involves incrementing the first counter C1 by 1 when the battery is unable to respond to the predetermined electrical request Z1, or incrementing the second counter C2 by 1 when it is still uncertain whether the battery can respond to the predetermined electrical request Z2.

[0050] Diagnostic steps E0, E1, E2, and E3 can be formulated based on different methods. For example, the diagnostic steps can be formulated based on a battery aging prediction model using battery state of charge and battery temperature as input information. In a variant, the diagnostic steps can be approximately formulated by a simple measurement of the battery voltage drop, which is compared to one or more thresholds during a predetermined or measured actuation of the current consumer.

[0051] Diagnostic steps E0, E1, E2, and E3 may also conform to the detailed description below and according to preferred variations:

[0052] Diagnostic steps E0, E1, E2, and E3 include a first step E0, which includes an optional initial inquiry sub-step after the vehicle is powered on. This initial inquiry sub-step is used to inquire about the diagnostic needs of the low-voltage battery. This need may occur after the vehicle is powered on and before the vehicle is started or driven, or when the vehicle's speed does not exceed a speed limit (exceeding which the safety of one or more occupants is no longer guaranteed without active diagnostics of the low-voltage battery 4).

[0053] In the event of a positive response to the initial query sub-step, and after the vehicle is started, the first step E0 includes a first sub-step, which involves controlling the electrical request component in the diagnostic mode of the low-voltage battery 4. For example, controlling the converter 8 in the diagnostic mode of the low-voltage battery 4.

[0054] It should be noted that, advantageously, the diagnostic requirements information enables the execution of the first sub-step to be authorized at each start of the vehicle, and in particular, to be executed only once at each start of the vehicle.

[0055] The method then performs a second sub-step, which involves performing a diagnosis of the low-voltage battery 4.

[0056] The second sub-step:

[0057] - This triggers multiple electrical requests to battery 4, each of which subsequently induces an inrush current, and monitors the occurrence of an internal fault in the control unit 10.

[0058] Then, based on each impact current, the values ​​of the voltage Umin and internal resistance Rint of battery 4 are determined.

[0059] Following the second sub-step, the first step E0 executes a third sub-step, which is used to determine the state STATUT for each value pair, the state being in the following condition:

[0060] - Unreliable state STNF occurs when the inrush current caused by the electrical request is too weak relative to a predetermined threshold during the granted time, or when an internal fault in the control unit 10 already exists during the granted time.

[0061] - Reliable State STF, when the inrush current caused by the electrical request is greater than or equal to the predetermined threshold during the granted time, and when there is no internal fault of the control unit 10 during the granted time.

[0062] One or more electrical requests are obtained, for example, by the control unit 10 sending a voltage setting value (i.e., a diagnostic voltage setting value) of the battery 4, which is applied to the input terminal 8.1 of the converter 8. Figure 1This setting is forced to be less than the initial voltage value at the terminals of the battery. Advantageously, this setting is adjusted to a value that allows for better accuracy in subsequent diagnostic steps. Ideally, this setting is less than the initial voltage between the terminals of battery 4 (that is, the voltage before converter 8 switches to diagnostic mode). For example, for a 12V low-voltage battery 4, when the low-voltage battery is charged and has a voltage close to 13V rather than 12V under no-load conditions, this setting is, for example, between 10V and 12V, especially 10.6V.

[0063] In a variant, based on the existing technology of converter 8, the converter 8 can be controlled by a current setting (for the flow current of battery 4) that replaces the setting value of the diagnostic voltage.

[0064] In the variant, this second sub-step triggers a unique electrical request.

[0065] In the variant, this situation takes the following form:

[0066] - Unreliable state STNF, when the inrush current triggered by the electrical request is too weak relative to a predetermined threshold over the granted time, or

[0067] - Reliable State STF, when the inrush current triggered by the electrical request is greater than or equal to the predetermined threshold during the granted time.

[0068] Throughout this document, "the surge current caused by the electrical request is too weak relative to a predetermined threshold" is understood as a comparison of the difference between the maximum intensity of the surge current during the granted time and the intensity at the beginning of the surge current and the predetermined intensity threshold. Needless to say, these intensities are absolute values. Furthermore, these currents and voltages are values ​​taken at the terminals of battery 4.

[0069] The granted time is, for example, 0.05 seconds, but ideally between 0.04 seconds and 0.1 seconds. The predetermined threshold for the current is, for example, 60A, but ideally between 50A and 130A. This corresponds to a minimized electrical request that forces the current supplied by battery 4 to increase by at least 60A in less than 0.05 seconds.

[0070] It is noted that the electrical request and the surge current simultaneously cause a voltage drop in the low-voltage battery 4, and the voltage Umin is thus the lowest voltage measured during the electrical request that causes the voltage drop.

[0071] The internal resistance Rint is the value of the voltage drop due to the impact current, which is divided by the current change due to the impact current, while assuming that the electromotive force of battery 4 is basically constant.

[0072] Alternatively, the method may count the number of consecutive STNF states on one or more driving routes. Thus, once this number exceeds a threshold (e.g., 6 consecutive STNF states), a service alarm is triggered to draw the driver's attention.

[0073] Diagnostic steps E0, E1, E2, and E3 include a second step E1. Following the first step E0, the method performs the second step E1, which analyzes the information SATUT, Umin, and Rint identified above and provides verified information regarding the internal resistance Rint reached during the inrush current used to calculate the internal resistance Rint and the minimized voltage Umin. This second step E1 involves retaining only the value pairs (Umin, Rint) associated with the condition (STATUT) having a reliable state (STF) and determining a unique characterizing value pair (Ur, Rr) based on the retained value pairs (Umin, Rint).

[0074] For example, the unique character pair (Ur, Rr) is equal to the last reserved character pair (Umin, Rint).

[0075] For example, the unique character pair (Ur, Rr) is the average of the reserved value pairs (Umin, Rint).

[0076] Note that when an internal fault of the control unit is detected during the granted time, the internal fault of the control unit forces the condition of the value pair associated with the unreliable state STNF, and the value pair is either not retained or ignored.

[0077] Advantageously, when the condition transitions from a reliable state STF to an unreliable state STNF due to an internal fault in the control unit 10, the method will ignore all value pairs after the occurrence of the fault until the next start of the vehicle.

[0078] For a variant that includes only a unique electrical request, the unique characterization pair (Ur, Rr) is equal to the unique value pair (Umin, Rint). In a further variant, the unique characterization pair (Ur, Rr) is unavailable when the unique value pair (Umin, Rint) from the unique electrical request is associated with the unreliable condition STNF, or when the unique value pair is ignored.

[0079] Diagnostic steps E0, E1, E2, and E3 include a third step, E2. Following the second step E1, the method performs this third step E2, based on a predetermined mapping of the voltage Umin to the internal resistance Rint, the predetermined mapping including at least:

[0080] -a first region Z1, wherein the first region corresponds to a low voltage Umin and / or a high internal resistance Rint,

[0081] -a third region Z3, wherein the third region corresponds to a high voltage Umin and / or a low internal resistance Rint,

[0082] -a second region Z2, wherein the second region is located between the first region Z1 and the third region Z3,

[0083] In the third step, the region Z1, Z2, Z3 where the unique characterization value pair Ur, Rr is located is determined according to the unique characterization value pair:

[0084] -when the unique characterization value pair is located in the third region Z3, the battery can respond to a predetermined electrical request, or

[0085] -when the unique characterization value pair is located in the first region Z1, the battery cannot respond to the predetermined electrical request, or

[0086] -when the unique characterization value pair is located in the second region Z2, it is still uncertain whether the battery can respond to the predetermined electrical request.

[0087] Thereby, this mapping can characterize the capability of the battery 4 to respond to an impact current from one or more simultaneous safety functions or devices defined above.

[0088] Figure 3 A simplified example of this mapping is shown. The horizontal axis represents the voltage Umin, with a plurality of specific values U1 to U5 of the voltage referenced, and the vertical axis represents the internal resistance Rint, with a plurality of specific values R1 to R4 of the internal resistance referenced.

[0089] The third region Z3 is the area between the first curve C3 and the horizontal axis, and the first curve intersects the horizontal axis at the shown voltage point U2. The first curve C3 is therefore a curve of the internal resistance Rint as a function of the voltage Umin. The curve C3 is increasing, starts from the value pair U2, R1 and ends at the value pair U5, R4, where U5>U2 and R4>R1. The first curve C3 also passes through two other specific value pairs U3, R2 and U4, R3 and consists of three consecutive segments, but the first curve may take a more complex form. In general, R1<R2<R3<R4 and U1<U2<U3<U4<U5.

[0090] It should be noted that these curves are increasing and non-strictly increasing. Therefore, throughout the present document, the definition of an increasing curve covers curves that include portions that are constant in abscissa or ordinate (that is, non-strictly decreasing curves).

[0091] The first region Z1 is the area between the second curve C4 and the vertical axis, which truncates the horizontal axis at the indicated voltage point U1. Curve C4 is also incremental, starting at the value pair U1, R1 and ending at the value pair U5, R4, but this is only a simplified example; the second curve C4 does not necessarily end at the same point as the first curve C3. The second curve C4 here takes a stepped form so that the first region Z1 corresponds to a voltage Umin less than or equal to U1 and / or an internal resistance Rint greater than or equal to R4. Of course, the second curve C4 can take other, more complex forms.

[0092] The second region Z2 is thus bounded by the first curve C3 on one hand and by the second curve C4 on the other.

[0093] This mapping is predetermined, for example, by an experimental plan that determines specific value pairs Umin and Rint to construct curves C4 and C3.

[0094] For example, for a 12V lead-acid battery, the value of U1 is 10V, the value of U5 is 16V, the value of R1 is 3mΩ, and the value of R4 is 14mΩ.

[0095] Note that the origin of the axis does not have a zero value, but corresponds to a value pair of 0V and R1, where R1 is non-zero (3mΩ in this example).

[0096] Note that the surge currents are, for example, in the range of 0A to 130A, and particularly in the range of 50A to 130A. For the low-voltage battery 4 of a motor vehicle, these intensities are relatively weak compared to the approximately 300A to 500A encountered, for example, during the start-up of a thermal engine. Therefore, for these surge currents, the minimum voltage Umin of battery 4 depends on the state of the battery, not on the intensity of the surge current. Consequently, this mapping can only have two dimensions: the minimum voltage Umin and the internal resistance Rint.

[0097] For more intense surge currents of approximately 300A to 400A, the mapping advantageously has three dimensions, becoming more accurate by supplementing the current with the minimum voltage Umin and internal resistance Rint.

[0098] Therefore, in the variation:

[0099] - During the first step (E0), the method determines the intensity of the induced surge current at the moment the voltage (Umin) is determined, and

[0100] The predetermined mapping also depends on the intensity of the induced impact current, and the three regions (Z1, Z2, Z3) extend into three volumes, and

[0101] - During the third step (E2), the method determines the three volumes in which the characterization values ​​(Umin, Rint) are located, which are associated with the intensity of the induced impact current:

[0102] - When the value associated with the intensity of the induced surge current is within the third volume from the third region (Z3), the battery is able to respond to the predetermined electrical request, or

[0103] - When the value associated with the intensity of the induced surge current is within the first volume from the first region (Z1), the battery is unable to respond to the predetermined electrical request, or

[0104] - When the value associated with the intensity of the induced surge current is in the second volume from the second region (Z2), it is still uncertain whether the predetermined electrical request can be responded to.

[0105] Diagnostic steps E0, E1, E2, and E3 include a fourth step, E3.

[0106] According to the present invention, Figure 2 The method executes the fourth step E3 from the start of the vehicle, wherein the fourth step is:

[0107] -When the vehicle starts, the start-up has a first delay of a first predetermined parameter-determinable duration, and

[0108] - At the end of the first delay, an authorization signal AUT-OK is transmitted, which is maintained only during the second predetermined parameter-determinable duration.

[0109] Thus, the authorized AUT-OK can, for example, authorize the use of the unique character pair (Ur, Rr) when the unique character pair is appropriate, that is, when successive electrical requests are determined and measurements of the voltage Umin and internal resistance Rint of the battery 4 are completed at each request, and when the unique character pair Ur, Rr is completely determined.

[0110] The first predetermined parameter duration is, for example, between 4 and 8 seconds, particularly 5 or 7 seconds. This first predetermined parameter duration is longer than the time required to implement the continuous electrical request.

[0111] Note that, for example, the time required for the electrical request to initiate the surge current and return the current to its value prior to the request is between 0.3 seconds and 2 seconds, particularly 0.4 seconds. Thus, for a predetermined, configurable duration of 5 seconds, the method can implement, for example, a series of 3 to 6 electrical requests.

[0112] The second predetermined duration can indicate the date of the update of the unique representation value pair Ur, Rr: when the update is too far in the past, then AUT-OK = false, and the method will not consider the same value of the unique representation value pair Ur, Rr twice consecutively.

[0113] However, this fourth step E3 is not mandatory. Moreover, the same result can be obtained in different ways, for example, by the autonomous management of the electrical request by the converter 8.

[0114] After the third step E2, the method performs the fifth step E4 described above.

[0115] In the variant, the fifth step involves incrementing the first counter C1 by 1 when:

[0116] - The authorization signal AUT-OK implements the transition from false to true E41, and

[0117] - The battery is unable to respond to the predetermined electrical request Z1, that is, the value pair is in the first region Z1.

[0118] Alternatively, increment the second counter C2 by 1 when:

[0119] - The authorization signal AUT-OK implements the transition from false to true E42, and

[0120] - It remains uncertain whether the predetermined electrical request Z2 can be responded to, that is, when the value pair is in the second region Z2.

[0121] Therefore, in this fifth step E4, the method records either the number of times the first counter C1 (memory battery 4) is unable to respond to the predetermined electrical request, or the number of times the counter C2 (memory battery 4) is detected as uncertain whether it can respond to the predetermined electrical request. These counters are updated once at the start of each trip. Thus, by using the unique characterization values ​​for Ur and Rr across multiple consecutive trips of the vehicle, the method can distinguish multiple alarm levels corresponding to different states of the battery 4.

[0122] Note that the values ​​taken by these counters are stored in memory from one trip to another, enabling reliable diagnosis of the battery over multiple consecutive trips.

[0123] Furthermore, after the fifth step E4, according to the method of the present invention, the first counter and the second counter C1, C2 are reset to zero values ​​when:

[0124] - The authorization signal AUT-OK implements the transition from false to true E43, and

[0125] - The battery is able to respond to a predetermined electrical request Z3, that is, the value pair is in the third region Z3.

[0126] In a variant, after the fifth step E4, the first counter and the second counters C1 and C2 are reset to zero according to the method of the invention when the battery is able to respond to a predetermined electrical request Z3, that is, when the value pair is in the third region Z3.

[0127] Therefore, the method takes into account the fact that the driver can recharge the battery 4 between two consecutive drives.

[0128] Note that the pre-detection of the false-to-true transition E41, E42, E43 of the authorization signal AUT-OK under any increment or zeroing of the first counter C1 and the second counter C2 can determine that: due to the first delay, the determined unique representation value is appropriate for Ur, Rr, that is, for example:

[0129] - The unique representation pair Ur and Rr left behind is the value pair of the last request in the request sequence. In the absence of an internal failure of control unit 10, the status STATUT remains in reliable state STF at each request, or

[0130] - The unique representation values ​​left behind, Ur and Rr, are the average of the values ​​of each request in the request sequence. In the absence of an internal failure of control unit 10, the status STATUT remains in reliable state STF at each request.

[0131] - The unique representation pair Ur and Rr that remains is the value pair of the last request in the request sequence with a status STF, and the status changes on the next request.

[0132] After step E4, the method executes step E5, which fires a maximum alarm AL-MAX when the first counter C1 is greater than or equal to the first predetermined threshold SEUIL 1, or when the second counter C2 is greater than or equal to the second predetermined threshold SEUIL 22.

[0133] The sixth step, E5, transmits an intermediate alarm AL-MED when the second counter C2 is greater than or equal to the third predetermined threshold SEUIL 2 and strictly less than the second predetermined threshold SEUIL 22, and when the first counter C1 is strictly less than the first predetermined threshold SEUIL 1.

[0134] In the variant, after step E4 in the fifth step, the method executes step E5, which fires a maximized alarm AL-MAX when:

[0135] - The sixth step E5 begins within the time window DUREE, which is contained between the start of the execution of the second sub-step and the stopping of the vehicle, and when:

[0136] - The authorization signal AUT-OK is true, and when:

[0137] - The first counter C1 is greater than or equal to the first predetermined threshold SEUIL 1, or the second counter C2 is greater than or equal to the second predetermined threshold SEUIL 22.

[0138] In the variant, the sixth step, E5, transmits an intermediate alarm AL-MED when:

[0139] - The sixth step E5 begins within the time window DUREE, which is contained between the start of the execution of the second sub-step and the stopping of the vehicle, and when:

[0140] - The authorization signal AUT-OK is true, and when:

[0141] - The second counter C2 is greater than or equal to the third predetermined threshold SEUIL 2 and strictly less than the second predetermined threshold SEUIL 22, and the first counter C1 is strictly less than the first predetermined threshold SEUIL 1.

[0142] It is noted that, advantageously, the intermediate alarm AL-MED and the maximum alarm AL-MAX are maintained until the vehicle is powered off, or even until the vehicle's computer goes into hibernation (the computer is powered off).

[0143] Note that, as an example of a threshold:

[0144] - The first predetermined threshold SEUIL 1 has a value of 1.

[0145] - The second predetermined threshold SEUIL 22 has a value of 2.

[0146] - The third predetermined threshold SEUIL 2 has a value of 1.

[0147] Therefore, the method can distinguish between multiple alarm levels corresponding to multiple severity levels. The maximum alarm (AL-MAX) is triggered when battery 4 is identified as posing a high risk to the safety of the driver and passengers. The intermediate alarm (AL-MED) is triggered when battery 4 is identified as posing a medium risk to the safety of the driver and passengers.

[0148] Based on the transmitted alarm, the method performs different actions. For example:

[0149] When the maximum alarm AL-MAX is emitted, the method is as follows:

[0150] - Activate the stop message to attract the driver's attention, and / or

[0151] - Activate the fixed indicator light associated with the battery to prompt the driver to check the battery 4, and / or

[0152] - Activate power supply interruptions for electrical consumers who are pre-defined as having non-priority over other consumers, especially comfort functions in the face of safety features.

[0153] When the maximum alarm is always true (issued) after a defined period of time, the method can also limit the speed of the vehicle, or even stop the vehicle.

[0154] Such comfort features include, for example, electrically heating the vehicle's seats or passenger compartment to temperatures exceeding the defrost temperature.

[0155] When the intermediate alarm AL-MED is transmitted, the method activates service information to draw the driver's attention and encourage the driver to at least recharge battery 4.

[0156] The information may be, for example, dashboard indicator lights, audible warnings, or messages displayed on the vehicle's computer screen.

[0157] Advantageously, the invention enables improvements to driver and passenger safety in electric vehicles by testing the battery 4 at startup (to ensure the safety functions it is equipped with).

[0158] More advantageously, in electric vehicles, the start-up phase of the thermal engine (which typically forces a strong electrical demand on battery 4 and thus allows for testing of the battery) no longer exists.

[0159] Therefore, this method, on the one hand, can determine the true capability of a battery (the power required to provide good operation of safety functions such as power steering) by systematically performing characterization tests at the start of driving, with the results of these tests being robust against various variables the battery may be subjected to (e.g., the battery's state of charge, temperature, aging level, damage level, or even its connection to the vehicle's network). On the other hand, this method can clearly inform the customer without interfering with the use of the vehicle.

[0160] Moreover, when needed, the method confirms the battery's true capacity (the power required to provide good operation of safety functions over multiple consecutive journeys) in order to provide the user with reliable warning information regarding the dangers the user is exposed to.

[0161] In addition, the method works preventively by reducing the electrical energy consumed by the battery so that the available power of the safety functions in the battery is prioritized.

[0162] Another advantage of this method is that, through the performed tests and analysis of the results, the true capability of the battery used to power the safety functions can be known: in fact, it is possible, for example, that even a well-charged battery (e.g., up to 90%) is still diagnosed as having a risk by this method, which is sufficient to simply conclude that the battery is very old or simply damaged and that its state of charge is thus misleading. Conversely, the method of the present invention prompts a demand for characterization of the battery (putting it into use), and the analysis of the results by the method described above provides the best possible profile of the functions that the battery can truly perform.

Claims

1. A control method for controlling a battery (4) of a vehicle, the vehicle including the battery (4) and a control unit (10) implementing the control method, the control method performing: - a diagnostic step (E0, E1, E2, E3) for diagnosing the battery (4) after the vehicle has been started and each time the vehicle is driven, characterized in that, The diagnostic provides the state among the three possible states (Z1, Z2, Z3) of the battery (4): - The battery is capable of responding to a predetermined electrical request (Z3), or - The battery is unable to respond to the predetermined electrical request (Z1), or - It remains uncertain whether the predetermined electrical request (Z2) can be responded to. Furthermore, following the diagnostic step, the control method performs a fifth step (E4), which involves incrementing the first counter (C1) by 1 when the battery is unable to respond to the predetermined electrical request (Z1), or incrementing the second counter (C2) by 1 when it is still uncertain whether the battery can respond to the predetermined electrical request (Z2). The feature is that, when the battery is able to respond to a predetermined electrical request (Z3), the fifth step (E4) resets the first counter and the second counter (C1, C2) to zero. Furthermore, after the fifth step (E4), the control method executes a sixth step (E5), in which a maximum alarm (AL-MAX) is triggered when the first counter (C1) is greater than or equal to the first predetermined threshold (SEUIL 1), or when the second counter (C2) is greater than or equal to the second predetermined threshold (SEUIL 22).

2. The method of claim 1, wherein, When the second counter (C2) is greater than or equal to the third predetermined threshold (SEUIL 2) and strictly less than the second predetermined threshold (SEUIL 22), and when the first counter (C1) is strictly less than the first predetermined threshold (SEUIL 1), the sixth step (E5) issues an intermediate alarm (AL-MED).

3. The control method according to claim 1 or 2, characterized in that, When the maximum alert (AL-MAX) is issued, the control method is as follows: - Activate a stop message to attract the driver's attention, and / or - Activate the fixed indicator light associated with the battery (4) to prompt the driver to check the battery (4), and / or - Activate power interruption for electrical consumers that are pre-defined as having non-priority over other consumers.

4. The control method according to claim 3, characterized in that, Activating power supply interruptions for electrical consumers that are pre-defined as having no priority over other consumers includes activating interruptions for comfort functions that are not priority over safety functions.

5. The control method according to claim 2, characterized in that, When the intermediate alarm (AL-MED) is transmitted, the control method activates service information to draw the driver's attention and encourage the driver to at least recharge the battery (4).

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