PREVENTIVE MONITORING OF OVERVOLTAGE AND UNDERVOLTAGE IN A CELLULAR BATTERY OF A SYSTEM

Abstract

A method for monitoring overvoltages and undervoltages of a cellular battery includes a step (10-40) in which maximum and minimum cell voltages are determined from among measured cell voltages. When the maximum cell voltage plus a first margin voltage exceeds a first threshold during a charging phase, a first limiting charging current is determined that can supply the battery based on the optimal maximum voltage, open-circuit voltage, and limiting internal charging resistance. Alternatively, when the minimum cell voltage plus a second margin voltage is below a second chosen threshold during a discharge phase, a first limiting discharge current is determined that can be supplied by the battery based on the optimal minimum voltage, open-circuit voltage, and limiting internal discharge resistance. Figure 3

Description

Title of the invention: PREVENTIVE MONITORING OF OVERVOLTAGES AND UNDERVOLTAGES IN A CELLULAR BATTERY OF A SYSTEM Technical field of the invention

[0001] The invention relates to cellular batteries, and more specifically to the preventive monitoring of overvoltages and undervoltages of such batteries. State of the art

[0002] In many fields, such as for example that of vehicles (possibly of the automobile type), cellular batteries are used to store electrical energy intended to power at least one electrical machine (possibly a motor) and / or a power supply circuit.

[0003] For example, in a vehicle, the cellular battery may serve to supply electrical energy to at least one electric drive unit that is part of the powertrain and connected to the main power supply circuit. In this case, the cellular battery is generally referred to as the "main" (or traction or power) battery because it provides electrical energy used for the vehicle's movement.

[0004] It should be noted that here we mean by “cellular battery” a battery comprising at least one electrical energy storage cell, rechargeable and possibly electrochemical (for example of lithium-ion (or Li-ion) or Ni-Mh or Ni-Cd type).

[0005] As those skilled in the art know, a cell battery can sometimes be subject to undervoltage, particularly during discharge, or overvoltage, particularly during charging. "Overvoltage" here refers to a voltage higher than the maximum voltage expected for the cell battery in question (taking into account its age and overall condition). Conversely, "undervoltage" here refers to a voltage lower than the minimum voltage expected for the cell battery in question (taking into account its age and overall condition).

[0006] Overvoltage or undervoltage is generally indicative of a malfunction of the cellular battery, and can cause its premature aging as well as possibly overheating which can lead to a fire, potentially dangerous for the vehicle and its passengers.

[0007] Since overvoltages and undervoltages in a cell battery are all the more concerning when the current flowing through it is high, they are generally monitored. Generally, when the device If monitoring detects an overvoltage or undervoltage for a duration exceeding a threshold, the cell battery is decoupled from all electrical machines and the power supply circuit coupled to it within its system. This decoupling is generally achieved by an interface (or isolation) device comprising, for example, contactors (or switches), possibly based on MOSFET(s), which are placed in an open (or non-conducting) state.

[0008] One disadvantage of this decoupling is that the system is suddenly prevented from functioning (which results in immobilization in the case of a vehicle), and therefore it is necessary to call in at least one technician from an after-sales service to diagnose the origin of the problem and possibly remedy this problem, which proves to be detrimental to the users of this system since suddenly they can no longer use it.

[0009] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0010] In particular, it proposes for this purpose a monitoring method intended to monitor overvoltages and undervoltages of a battery having optimal maximum and minimum voltages, an open-circuit voltage and limiting internal resistances for charging and discharging, and comprising cells suitable for storing and supplying electrical energy and each having a measurable cell voltage.

[0011] This monitoring method is characterized by the fact that it includes a step in which:

[0012] - maximum cellular voltage and minimum cellular voltage are determined from among the measured cellular tensions, and

[0013] - when this maximum cellular voltage is added to a first voltage of If the margin is greater than a first chosen threshold during a battery charging phase, a first maximum charging current is determined that can power the battery based on the optimal maximum voltage, open-circuit voltage, and maximum internal charging resistance, or

[0014] - when the minimum cell voltage is added to a second margin voltage is less than a second threshold chosen during a battery discharge phase, a first limit discharge current that can be supplied by the latter is determined as a function of the optimal minimum voltage, open-circuit voltage and limit internal discharge resistance.

[0015] Thanks to the invention, it is now possible to prevent the charging current supplying the cellular battery from exceeding the first determined charging current limit, or to prevent the discharge current supplied by the cellular battery from being greater than the first determined discharge limit current, in order to avoid decoupling of the cellular battery.

[0016] The monitoring method according to the invention may include other features which may be taken separately or in combination, and in particular:

[0017] - in its stage, when the maximum cellular voltage added to the first If the margin voltage is greater than the first threshold chosen during a battery charging phase, a second overall charging current limit can be determined that can power the battery based on at least the first charging current limit, a third charging current limit resulting from a battery architecture, a fourth charging current limit resulting from a battery charging voltage limit, and a fifth static battery charging current limit determined.Similarly, when the minimum cell voltage plus the second margin voltage is less than a second chosen threshold during a battery discharge phase, a second overall discharge limit current that can be supplied by the battery can be determined as a function of at least the first discharge limit current, a third discharge limit current resulting from the battery architecture, a fourth discharge limit current resulting from a battery discharge limit voltage, and a fifth static battery discharge limiting current determined; .

[0018] - in the presence of the first option, in its stage, when the cellular tension If the maximum added to the first margin voltage is greater than the first threshold chosen during a battery charging phase, a global charging power limit that can be supported by the battery can be determined based on a predefined battery charging power limit and a first product of the second global charging current limit determined by a determined maximum battery voltage limit or the optimal maximum voltage.Similarly, when the minimum cell voltage plus the second margin voltage is less than a second chosen threshold during a battery discharge phase, a global discharge power limit that can be supplied by the battery can be determined as a function of a predefined battery discharge power limit and a second product of the second global discharge current limit determined by a determined minimum battery voltage limit or the optimal minimum voltage; .

[0019] - in the presence of the last sub-option, in its step, one can determine the The overall recharge power limit can be determined by choosing a larger value from the first product and the predefined battery recharge power limit, and the overall discharge power limit can be determined by choosing a smaller value from the second product and the predefined battery discharge power limit;

[0020] - also in the presence of the first option, in its step, one can determine each of the fifth static limiting current for battery charging and fifth static limiting current for battery discharging as a function of a current state of charge of the battery, a current capacitive health state of the battery, an average internal temperature in the battery, determined from measured cell temperatures of the cells, and maximum cell temperature and minimum cell temperature determined from the measured cell temperatures;

[0021] - in the presence of the last sub-option, in its step, one can determine the fifth static battery charging limiting current by choosing a smaller value from first, second and third charging limiting current values ​​determined, respectively, based on average internal temperature, maximum measured cell temperature and minimum measured cell temperature, in a first charging table establishing a correspondence between temperatures, states of charge, capacitive health states, and charging limiting current values.Similarly, the fifth static battery discharge limiting current can be determined by choosing a larger value from first, second, and third discharge limiting current values ​​determined, respectively, as a function of mean internal temperature, maximum measured cell temperature, and minimum measured cell temperature, in a second discharge table establishing a correspondence between temperatures, states of charge, capacitive health states, and discharge limiting current values; .

[0022] - in its step, maximum cell temperature and can be determined minimum cellular temperature among measured cellular temperatures of the cells, and each of the first and second thresholds chosen can be determined based on these determined maximum and minimum cellular temperatures;

[0023] - in the presence of the last option, in its step, the first can be determined The threshold is chosen by selecting a smaller value from among the first and second threshold values ​​determined, respectively, based on the maximum and minimum measured cell temperatures, in a third recharging table that establishes a correspondence between maximum and minimum cell temperatures and the first and second threshold values. Similarly, the second threshold can be determined by selecting a larger value from among the third and fourth threshold values ​​determined, respectively, based on the maximum and minimum measured cell temperatures, in a fourth discharge table that establishes a correspondence between maximum and minimum cell temperatures and third and fourth threshold values.

[0024] The invention also proposes a computer program product comprising a set of instructions which, when executed by processing means, is suitable for implementing a monitoring method of the type presented above for monitoring overvoltages and undervoltages of a battery having optimal maximum and minimum voltages, an open-circuit voltage and limiting internal resistances for charging and discharging, and comprising cells suitable for storing and supplying electrical energy and each having a measurable cell voltage.

[0025] The invention also proposes a monitoring device for monitoring overvoltages and undervoltages of a battery having optimal maximum and minimum voltages, an open-circuit voltage and limiting internal resistances for charging and discharging, and comprising cells suitable for storing and supplying electrical energy and each having a measurable cell voltage.

[0026] This monitoring device is characterized in that it comprises at least one processor and at least one memory arranged to perform the operations consisting of:

[0027] - to determine maximum cellular voltage and minimum cellular voltage among the measured cellular tensions, and

[0028] - when this maximum cellular voltage is added to a first voltage of If the margin is greater than a first chosen threshold during a battery charging phase, a first maximum charging current must be determined based on the optimal maximum voltage, open-circuit voltage, and maximum internal charging resistance.

[0029] - when the minimum cellular voltage is added to a second voltage of margin is less than a second threshold chosen during a battery discharge phase, to determine a first limit discharge current that can be supplied by the latter as a function of the optimal minimum voltage, open-circuit voltage and limit internal discharge resistance.

[0030] The invention also proposes a system comprising, on the one hand, a battery having optimal maximum and minimum voltages, an open-circuit voltage and limiting internal resistances for charging and discharging, and comprising cells suitable for storing and supplying electrical energy and each having a measurable cell voltage, and, on the other hand, a monitoring device of the type presented above. Brief description of the figures

[0031] Other features and advantages of the invention will become apparent from an examination of the detailed description below, and the accompanying drawings, in which:

[0032] [Fig. 1] schematically and functionally illustrates an example of an embodiment of a vehicle comprising a monitoring device according to the invention and a powertrain with an electric drive unit powered by a cellular battery associated with a battery computer,

[0033] [Fig.2] schematically and functionally illustrates an example of the realization of a battery calculator comprising a monitoring device according to the invention, and

[0034] [Fig.3] schematically illustrates an example of an algorithm implementing an monitoring method according to the invention. Detailed description of the invention

[0035] The invention aims in particular to provide a monitoring method, and an associated DS monitoring device, intended to allow preventive monitoring, in a system S, of overvoltages and undervoltages of a cellular battery BC.

[0036] In what follows, system S is considered, by way of non-limiting example, to be a motor vehicle, such as a car, as illustrated in [Fig. 1]. However, the invention is not limited to this type of system. It relates to any type of system comprising at least one cellular battery with cells suitable for storing and supplying electrical energy. Thus, it relates to vehicles (land, sea (or river), and air), mobile machinery (including those performing a lifting function), electronic devices (possibly household appliances and / or possibly mobile), installations (possibly industrial), and buildings, for example.

[0037] Furthermore, in what follows, by way of non-limiting example, the vehicle S comprises an all-electric powertrain (or PMT) (and therefore includes at least one electric drive unit associated with a cellular battery). However, the PMT could be of the hybrid type (and in this case, the vehicle S is powered by at least one internal combustion engine and one electric drive unit).

[0038] A system S (here a vehicle) comprising an all-electric GMP transmission chain (and therefore comprising at least one electric drive machine MME), a CS supervisory computer, a BS auxiliary battery, a BC cellular battery associated with a CB battery computer and an DI interface (or isolation) device, a CV converter, an RB on-board network, and a DS monitoring device according to the invention, is schematically represented in [Fig.1].

[0039] The auxiliary battery BS is responsible for supplying electrical power to the vehicle's on-board electrical system RB, supplementing that supplied by the CV converter powered by the cell battery BC via a main electrical circuit, and sometimes replacing this CV converter. For example, this auxiliary battery BS may be arranged as a very low voltage battery (typically 12 V, 24 V or 48 V). It is rechargeable at least by the CV converter. In the following, we consider, as a non-limiting example, that the BS service battery is a 12 V Lithium-ion type.

[0040] The RB on-board network is an electrical power supply network to which electrical (or electronic) equipment (or components) that consume electrical energy are coupled.

[0041] The main electrical circuit (or "high voltage" or "power" circuit) is connected, on the one hand, to the cellular battery BC via the interface device DI, and, on the other hand, to electronic equipment, such as the CV converter and the drive machine MME. It also allows the cellular battery BC to be recharged by an external power source SA temporarily connected to the vehicle S, for example via a charging cable CR temporarily connected to a charging connector CN of the vehicle S.

[0042] The transmission system has a powertrain which, in this case, is purely electric, and therefore includes, in particular, in addition to its (electric) drive machine, a drive shaft and a transmission shaft. The term "electric drive machine" here refers to an electric machine arranged to provide motor torque to move the system S (here, a vehicle), and possibly to recover torque (for example, during regenerative braking). The operation of the powertrain is supervised by a control unit.

[0043] The drive machine MME (here an electric motor) is coupled to the cell battery BC via the main electrical circuit, in order to be supplied with electrical energy, and also possibly to supply this cell battery BC with electrical energy during a torque recovery phase. It is coupled to the motor shaft, to provide it with torque by rotational drive. This motor shaft is here coupled to a reduction gear RD which is also coupled to the transmission shaft, itself coupled to a first set of wheels Tl, preferably via a differential DF.

[0044] This first train Tl is here located in the front part PVV of the vehicle S. But in a variant this first train Tl could be the one which is here referenced T2 and which is located in the rear part PRV of the vehicle S.

[0045] The operation of the MME drive machine is controlled by a machine computer (not shown), and supervised by the CS supervisory computer.

[0046] The CV converter is also responsible, here, during the driving phases of vehicle S, for converting a portion of the electrical current stored in the cellular battery BC to supply converted electrical current to the on-board network RB and the auxiliary battery BS (to recharge it). It is also, here, electrically coupled, via the main electrical circuit, to the charging connector CN of vehicle S which, during a charging phase of the cellular battery BC, is, here, intended to be temporarily coupled to an external power source SA to the vehicle S, via a charging cable CR.

[0047] It will be noted, as illustrated non-limitingly in [Fig. 1], that the CV converter can be part of an internal CH charger also comprising a CA computer responsible, at least, for controlling the charging of the cellular battery BC.

[0048] The BC cellular battery comprises N CE electrical energy storage cells, with N > 1. It should be noted that the CE cells can optionally be grouped into identical or different MC modules, as illustrated non-limitingly in [Fig.1].

[0049] For example, EC cells can be electrochemical. Thus, they can, for example, be of the lithium-ion (or Li-ion) or Ni-Mh or Ni-Cd type.

[0050] Also, for example, the BC cellular battery can be of the low voltage type (typically 450 V by way of illustration). But it could be of the medium voltage or high voltage type, or even very low voltage (for example 48 V).

[0051] The N CE cells are associated respectively with N voltage sensors (not shown) responsible for determining respectively N cell voltages uc at their terminals, and with N temperature sensors (not shown) responsible for determining respectively N cell temperatures te.

[0052] It will be noted that the cellular battery BC has an optimal maximum voltage Umaxo and an optimal minimum voltage Umino, an open-circuit voltage UOCV, an internal limiting resistance for charging Rilr and an internal limiting resistance for discharging Rild which are known internally (for example by the battery calculator CB).

[0053] Furthermore, the BC cellular battery is (here) associated with a BB battery housing which includes, in particular, the DI interface (or isolation) device, voltage / current measurement means (not shown), and a CB battery calculator. The BC cellular battery and the BB battery housing can constitute a battery assembly (or "pack").

[0054] The interface (or isolation) device DI is arranged to isolate, when necessary, the cell battery BC from the electric motor MME and more generally from the main electrical circuit. It includes, for example, contactors (or switches), possibly based on MOSFET(s), which can each be placed in an open (or non-conducting) state or a closed (or conducting) state.

[0055] The CB battery calculator controls the DI interface device. Furthermore, it centralizes current measurements, voltage measurements (in particular those (uc) determined by the N voltage sensors (associated respectively with the N CE cells)) and cell temperature measurements te (which are determined by the N voltage sensors (associated respectively with the N CE cells)), and determines The battery cell BC parameters are determined based on these measurements, including its minimum voltage Umin and maximum voltage Umax, its current state of charge (SOC) socBc and its current state of capacity (SOHC) sohcBc, as well as potentially its current state of resistance (SOHR) state of health. Furthermore, the battery CB computer also exchanges information with the GMP's CS monitoring computer.

[0056] It should be noted that in the example illustrated, but not limited to, in [Fig. 1], the vehicle S also includes a distribution box BD to which the auxiliary battery BS, the CV converter, and the on-board network RB are coupled. This distribution box BD is responsible for distributing into the on-board network RB the electrical energy produced by the CV converter or stored in the auxiliary battery BS, to power the electrical components (or equipment) coupled to the on-board network RB, according to power demands received (in particular from the powertrain control unit CS).

[0057] As mentioned above, the invention proposes in particular a monitoring method intended to allow preventive monitoring in the system S (here a vehicle) of overvoltages and undervoltages of the cellular battery BC.

[0058] This (monitoring) method can be implemented at least partially by the DS monitoring device (illustrated in [Fig. 2]), which for this purpose comprises at least one PR1 processor, for example a digital signal processor (or DSP), and at least one MD memory. This DS monitoring device can therefore be implemented as a combination of electrical or electronic circuits or components (or "hardware") and software modules (or "software"). For example, it could be a microcontroller.

[0059] The MD memory is random access memory (RAM) to store instructions for the implementation by the PR1 processor of at least part of the monitoring process. The PR1 processor may comprise integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is defined as any type of device capable of performing at least one electrical or electronic operation.

[0060] In the example illustrated, but not limited to, in Figures 1 and 2, the DS monitoring device is part of the CB battery control unit. However, it could be part of another control unit embedded in the S system and performing at least one other function, or it could comprise its own dedicated control unit.

[0061] As illustrated, without limitation, in [Fig. 3], the (monitoring) method according to the invention comprises a step 10-40 which is implemented each time the System S uses its BC cellular battery (whether in a charging phase or in a discharging phase).

[0062] Step 10-40 of the process includes a substep 10 in which a maximum cell voltage ucmax and a minimum cell voltage ucmin are determined from among all the measured cell voltages uc.

[0063] Step 10-40 of the process then includes a substep 20 which relates to both a charging phase of the BC battery and a discharging phase of the BC cellular battery.

[0064] In this substep 20, when the maximum cell voltage ucmax plus a first margin voltage ulm exceeds a first threshold chosen `si` (i.e., ucmax + ulm > `si`), an overvoltage or near-overvoltage situation occurs. In this case, a first maximum charging current limit `Illr` that can supply the cell battery BC is determined (for example, by the DS monitoring device), based on the optimal maximum voltage `Umaxo`, the open-circuit voltage `UOCV`, and the internal charging resistance limit `Rilr`. Thus, the charging current supplying the cell battery BC is prevented from exceeding the first determined maximum charging current limit `Illr`, to avoid the occurrence of a possible overvoltage. This advantageously prevents decoupling of the cell battery BC, and therefore increases its availability.

[0065] Still in substep 20, when the minimum cell voltage ucmin plus a second margin voltage u2m is less than a second chosen threshold s2 (i.e., ucmin + u2m < s2), the situation is undervoltage or near undervoltage. In this case, a first maximum discharge current Illd that can be supplied by the cell battery BC is determined (for example, by the DS monitoring device), based on the optimal minimum voltage Umino, the open-circuit voltage UOCV, and the maximum internal discharge resistance Rild. Thus, the discharge current supplied by the cell battery BC is prevented from exceeding the first determined maximum discharge current Illd, to avoid the occurrence of a possible undervoltage. This advantageously prevents decoupling of the cell battery BC, and therefore increases its availability.

[0066] It will be understood that in substep 20, when the maximum cell voltage ucmax plus the first margin voltage ulm is less than or equal to the first threshold chosen si (i.e., ucmax + ulm < si), step 10-40 of the process is repeated (for example, by the DS monitoring device) with new measurements of the cell voltages uc, without limiting the charging current. Similarly, in substep 20, when the minimum cell voltage ucmin plus the second margin voltage u2m is greater than or equal to the second threshold chosen s2 (i.e., ucmin + u2m > s2), we (for example, the DS monitoring device) perform step 10-40 of the process again with new measurements of the cell voltages uc, without limitation of the discharge current.

[0067] For example, in substep 20, one (for example the DS monitoring device) can determine the first limiting recharge current Illr using the equation:

[0068] [Math.l] IUr=min(0, voc^um^o )

[0069] Similarly, in substep 20, one (for example, the DS monitoring device) can determine the first limiting discharge current Illd using the equation:

[0070] [Math.2] IUd = max(0, )

[0071] Preferably, the first charging current limit Illr is determined only if the maximum cell voltage ucmax plus the first margin voltage ulm is greater than the first chosen threshold for at least a first chosen duration. For example, the first chosen duration may be between 100 ms and 200 ms.

[0072] Also preferably, the first limit discharge current Illd is determined only if the minimum cell voltage ucmin plus the second margin voltage u2m is less than the second chosen threshold s2 for at least the first chosen duration.

[0073] Also, for example, in substep 10 of step 10-40, one (for example, the DS monitoring device) can also determine a maximum cell temperature tcmax and a minimum cell temperature tcmin from among the measured cell temperatures te of the CE cells. In this case, in this substep 10, one (for example, the DS monitoring device) can, for example, also determine each of the first si and second s2 thresholds chosen as a function of these determined maximum cell temperature tcmax and minimum cell temperature tcmin.

[0074] To do this, one (for example, the DS monitoring device) can, for example, determine the first threshold by choosing the smallest value among first vsl and second vs2 threshold values ​​determined in a (third) reload table (or map) tr3 establishing a correspondence between maximum and minimum cellular temperatures and first and second threshold values. It will be understood that these first vsl and second vs2 threshold values ​​are determined in the third reload table tr3 as a function of the temperature, respectively. The maximum cellular temperature tcmax is measured, and the minimum cellular temperature tcmin is measured. We then have si = min(vsl, vs2).

[0075] Similarly, one (for example, the DS monitoring device) can, for example, determine the second threshold s2 by choosing the largest value among the third vs3 and fourth vs4 threshold values ​​determined in a (fourth) discharge table (or map) td4 establishing a correspondence between maximum and minimum cell temperatures and the third and fourth threshold values. It will be understood that these third vs3 and fourth vs4 threshold values ​​are determined in the fourth discharge table td4 as a function of the measured maximum cell temperature tcmax and the measured minimum cell temperature tcmin, respectively. We then have s2 = max(vs3, vs4).

[0076] In one embodiment, the first if and second s2 thresholds could be predefined (and therefore fixed).

[0077] It should be noted that during a charging phase, when a limitation (Illr) of the charging current has been determined, it is possible to stop this limitation when the maximum cell voltage ucmax plus the first margin voltage ulm falls below a third threshold s3 chosen and preferably different from the first threshold si (and for example lower than the latter (si)) (i.e., ucmax + ulm < s3), preferably for at least a second chosen duration. In this situation, step 10-40 of the process is repeated (for example, by the DS monitoring device) with new measurements of the cell voltages uc but without limiting the charging current. For example, the second chosen duration could be between 150 ms and 250 ms.

[0078] Similarly, during a discharge phase, when a limitation (111) of the discharge current has been determined, it is possible to discontinue this limitation when the minimum cell voltage ucmin plus the second margin voltage u2m falls below a fourth threshold s4 chosen and preferably different from the second threshold s2 (and for example lower than the latter (s2)) (i.e., ucmin + u2m < s4), preferably for at least the second chosen duration. In this situation, step 10-40 of the process is repeated (for example, by the DS monitoring device) with new measurements of the cell voltages uc but without the discharge current limitation.

[0079] It will be noted that in substep 10 one (for example the DS monitoring device) can, for example, also determine each of the third s3 and fourth s4 thresholds chosen as a function of the maximum cell temperature tcmax and minimum cell temperature tcmin determined.

[0080] To do this, one (for example the DS monitoring device) can, for example, determine the third threshold s3 by choosing the smallest value among The fifth vs5 and sixth vs6 threshold values ​​are determined in a fifth reload table (or map) tr5, which establishes a correspondence between maximum and minimum cell temperatures and these fifth and sixth threshold values. It should be understood that these fifth vs5 and sixth vs6 threshold values ​​are determined in the fifth reload table tr5 based on the measured maximum cell temperature tcmax and the measured minimum cell temperature tcmin, respectively. Therefore, s3 = min(vs5, vs6).

[0081] Similarly, one (for example, the DS monitoring device) can, for example, determine the fourth threshold s4 by choosing the largest value among the seventh vs7 and eighth vs8 threshold values ​​determined in a sixth discharge table (or map) td6 establishing a correspondence between maximum and minimum cell temperatures and the seventh and eighth threshold values. It will be understood that these seventh vs7 and eighth vs8 threshold values ​​are determined in the sixth discharge table td6 as a function of the measured maximum cell temperature tcmax and the measured minimum cell temperature tcmin, respectively. We then have s4 = max(vs7, vs8).

[0082] In one embodiment, the third s3 and fourth s4 thresholds could be predefined (and therefore fixed).

[0083] For example, and as illustrated non-limitingly in [Fig. 3], step 10-40 of the process may also include a substep 30 in which a second overall recharge current limit I21rg can be determined to supply the cell battery BC, or a second overall discharge current limit I21dg can be supplied by the cell battery BC. These second overall recharge current limit I21rg and second overall discharge current limit I21dg are intended to take into account all the constraints of the battery assembly, including architectural constraints (connectors, cables, and series and / or parallel connections) and current limitations (related to the chemistry of the cell battery BC), unlike the first recharge current limit Illr and first discharge current limit Illd, which essentially only take into account voltage and possibly temperature constraints.

[0084] In this substep 30, when the maximum cell voltage ucmax plus the first margin voltage ulm exceeds the first threshold if chosen during a charging phase of the cell battery BC, one (for example, the DS monitoring device) can determine the second overall charging limit current I21rg as a function of at least the first charging limit current Illr, a third charging limit current I31r resulting from the architecture of the battery BC, and a fourth charging limit current I41r resulting from a charging limit voltage of the battery. BC cellular battery, and a fifth static charging limiting current I51sr of the determined BC cellular battery.

[0085] Still in substep 30, when the minimum cell voltage ucmin plus a second margin voltage u2m is less than the second chosen threshold s2 during a discharge phase of the cell battery BC, one (for example the DS monitoring device) can determine the second overall discharge limit current I21dg as a function of at least the first discharge limit current Illd, a third discharge limit current Bld resulting from the architecture of the cell battery BC, a fourth discharge limit current I41d resulting from a discharge limit voltage of the cell battery BC, and a fifth static discharge limiting current I51sd of the cell battery BC determined.

[0086] For example, in substep 30, the second overall recharge limit current I21rg can be determined (for example, by the DS monitoring device) using the equation I21rg = rl*max(Illr, Blr, I41r, I51sr). Similarly, in substep 30, the second overall discharge limit current I21dg can be determined (for example, by the DS monitoring device) using the equation I21dg = r2*min(Illd, Bld, I41d, I51sd).

[0087] The parameters rl and r2 are weighting coefficients that can either always be equal to one (and therefore fixed), or be variable. In the second alternative, rl and r2 can, for example, be determined as follows.

[0088] For example, in substep 30, one (for example the DS monitoring device) can determine the variable parameter rl using the following equation:

[0089] [Math.3] rl = rcl-max(0, min(rcsl, ftK^Uerrÿdt) )

[0090] where rcl is a maximum recharge value which can be between 0 and 1, rcsl is a maximum recharge correction value for example equal to 0.5 or 0.75, Ki is an integral action coefficient (for example chosen equal to 0.005), and Uerrl is equal to (ucmin - si).

[0091] Also, for example, in substep 30, one (for example the DS monitoring device) can determine the variable parameter r2 using the following equation:

[0092] [Math.4] r2 = rc2-max{Q, min(rcs2, f(Ki*Uerr2)dt) )

[0093] where rc2 is a maximum discharge value which can be between 0 and 1, rcs2 is a maximum discharge correction value, for example equal to 0.5 or 0.75, Ki is an integral action coefficient (for example chosen to be equal to 0.005), and Uerr2 is equal to (ucmin - s2).

[0094] Also, for example, and as illustrated but not limited to [Fig. 3], the step 10-40 of the process may also include a substep 40 in which one (for example the DS monitoring device) can determine an overall recharge power limit Plrg that can be supported by the cellular battery BC or an overall discharge power limit Pldg that can be supplied by the cellular battery BC.

[0095] In this substep 40, when the maximum cell voltage ucmax plus the first margin voltage ulm exceeds the first threshold chosen if, and therefore indicates an overvoltage or near-overvoltage situation, the overall charging power limit Plrg that the cell battery BC can withstand can be determined (for example, by the DS monitoring device). This limit is based on a predefined (and therefore fixed) charging power limit Plr of the cell battery BC and a first product pl of the second overall charging current limit I21rg determined by a maximum charging voltage limit Umaxl of the cell battery BC or the optimal maximum voltage Umaxo. Thus, the charging power supported by the cell battery BC is also prevented from exceeding the determined overall charging power limit Plrg, further preventing the occurrence of a possible overvoltage.This advantageously helps to further prevent decoupling of the cellular battery (BC), and therefore increases its availability.

[0096] For example, in substep 40, one (for example the DS monitoring device) can determine the maximum limit voltage Umaxl using the equation Umaxl = UOCV - I21rg* Rilr.

[0097] Similarly, in this substep 40, when the minimum cell voltage ucmin plus the second margin voltage u2m is lower than the second threshold s2 chosen during a discharge phase of the cell battery BC, the overall discharge limit power Pldg that can be supplied by the cell battery BC can be determined (for example, by the DS monitoring device) as a function of a predefined (and therefore fixed) overall discharge limit power Pld of the cell battery BC and a second product p2 of the second overall discharge limit current I21dg determined by a determined minimum limit voltage Uminl of the cell battery BC or the optimal minimum voltage Umino. Thus, the discharge power supplied by the cell battery BC is also preventively prevented from exceeding the determined overall discharge limit power Pldg, to further avoid the occurrence of a possible undervoltage. This advantageously avoids even more so a decoupling of the cellular battery BC, and therefore increasing the availability of the latter (BC).

[0098] For example, in substep 40, one (for example the DS monitoring device) can determine the minimum limit voltage Uminl using the equation Uminl = UOCV - I21dg* Rild.

[0099] It should be noted that in substep 40, one (for example, the DS monitoring device) can, for example, determine the overall maximum charging power Plrg by choosing the largest value among the first product pl and the maximum charging power Plr of the predefined BC cellular battery (i.e., Plrg = max(pl, Plr)). It is recalled that pl can be equal to either I21rg*Umaxl or I21rg*Umaxo.

[0100] Similarly, in substep 40, one (for example, the DS monitoring device) can, for example, determine the overall discharge limit power Pldg by choosing the smallest value among the second product p2 and the discharge limit power Pld of the predefined BC cell battery (i.e., Plrg = min(p2, Pld)). It is recalled that p2 can be equal to either I21dg*Uminl or I21dg*Umino.

[0101] Also, for example, in substep 30, one (for example, the DS monitoring device) can determine each of the fifth static charging limiting current I51sr of the BC cell battery and the fifth static discharging limiting current I51sd of the BC cell battery as a function of the current state of charge socBc of the BC cell battery, the current capacitive health state sohcBc of the BC cell battery, an average internal temperature timBc in the BC cell battery, and the maximum cell temperature tcmax and minimum cell temperature tcmin. It should be noted that the average internal temperature timBC is determined from all the measured cell temperatures te of the CE cells, and the maximum cell temperature tcmax and minimum cell temperature tcmin are determined from all the measured cell temperatures te.

[0102] To do this, in substep 40, one (for example, the DS monitoring device) can, for example, determine the fifth static charging current limit I51sr of the cellular battery BC by choosing the smallest value among the first vilrl, second vilr2, and third vilr3 charging current limit values ​​determined in a first charging table (or map) tri establishing a correspondence between temperatures, states of charge, capacitive health states, and charging current limit values. It should be noted that this determination of the first vilrl, second vilr2, and third vilr3 limiting current values ​​is carried out in the first charging table tri, as a function of the mean internal temperature timBC and cellular temperature, respectively. maximum measured tcmax and minimum measured cell temperature tcmin. We then have I51sr = min(vilr1, vilr2, vilr3).

[0103] Similarly, in substep 40, one (for example, the DS monitoring device) can, for example, determine the fifth static discharge limiting current I51sd of the BC cell battery by choosing the largest value among the first vildl, second vild2, and third vild3 discharge limiting current values ​​determined in a second discharge table (or map) tr2 establishing a correspondence between temperatures, states of charge, capacitive health states, and discharge limiting current values. It should be noted that this determination of the first vildl, second vild2, and third vild3 limiting current values ​​is carried out in the second charging table td2, as a function, respectively, of the mean internal temperature timBC, the measured maximum cell temperature tcmax, and the measured minimum cell temperature tcmin. We then have I51sd = min(vildl, vild2, vild3).

[0104] It will also be noted, as illustrated non-limitingly in [Fig.1], that the battery calculator CB (or the computer of the monitoring device DS) can also include a mass memory MM1, in particular to store each cell voltage uc, each cell temperature te, the state of charge socBc, the capacitive health state sohcBC, the maximum voltage Umaxo, the optimal minimum voltage Umino, the maximum charging power Plr, and the maximum discharge power Pld, and the various corresponding tables (or maps), as well as any intermediate data involved in all its calculations and processing.Furthermore, this CB battery calculator (or the DS monitoring device calculator) may also include an IE input interface for receiving at least each cell voltage uc, each cell temperature te, the state of charge socBC, the capacitive health state sohcBC, the maximum voltage Umaxo, the minimum optimal voltage Umino, the maximum charging power, and the maximum discharging power, in a manner known per se, by means of a PR2 digital signal processor. In addition, this CB battery calculator (or the DS monitoring device calculator) may also include an IS output interface, notably for delivering each alert message, each message containing a first maximum discharging or charging current, or a second maximum discharging or charging current, or an overall maximum charging power, or an overall maximum discharging power.

[0105] It should also be noted that the invention also proposes a computer program product (or computer program) comprising a set of instructions which, when executed by processing means such as electronic circuits (or hardware), such as for example the PR1 processor, is suitable for implementing the monitoring method described above for preventively monitoring, in system S, overvoltages and undervoltages of the BC cellular battery.

Claims

1. Demands A method for monitoring the overvoltages and undervoltages of a battery (BC) having optimal maximum and minimum voltages, open-circuit voltage, and limiting internal resistances for charging and discharging, and comprising cells (CE) suitable for storing and supplying electrical energy and each having a measurable cell voltage, characterized in that it comprises a step (10-40) in which - Maximum and minimum cellular voltages are determined from among the measured cellular voltages, and - when said maximum cell voltage plus a first margin voltage is greater than a first threshold chosen during a charging phase of said battery (BC), a first maximum charging current that can supply said battery (BC) is determined as a function of said optimal maximum voltage, open-circuit voltage and internal charging resistance limit, or - when said minimum cell voltage plus a second margin voltage is less than a second threshold chosen during a discharging phase of said battery (BC), a first maximum discharge current that can be supplied by said battery (BC) is determined as a function of said optimal minimum voltage, open-circuit voltage and internal discharge resistance limit, and - when said maximum cell voltage plus said first margin voltage is greater than said first threshold chosen during a charging phase of said battery (BC),a second overall maximum charging current is determined that can power the latter (BC) as a function of at least said first maximum charging current, a third maximum charging current resulting from an architecture of said battery (BC), a fourth maximum charging current resulting from a maximum charging voltage of said battery (BC), and a fifth static limiting charging current of said battery (BC) determined, or, - when said minimum cell voltage plus said second margin voltage is less than a second chosen threshold during a discharge phase of said battery (BC), a second overall discharge current limit that can be supplied by the latter (BC) is determined as a function of at least said first limit current of discharge, of a third limiting discharge current resulting from said battery architecture (BC), of a fourth limiting discharge current resulting from a limiting discharge voltage of said battery (BC), and of a fifth static limiting discharge current of said battery (BC) determined.

2. The method according to claim 1, characterized in that in said step (10-40), when said maximum cell voltage plus said first margin voltage is greater than said first threshold chosen during a charging phase of said battery (BC), a global charging power limit that can be supported by the latter (BC) is determined as a function of a predefined charging power limit of said battery (BC) and a first product of said second global charging current limit determined by a maximum voltage limit of said battery (BC) determined or said optimal maximum voltage, or when said minimum cell voltage plus said second margin voltage is less than a second threshold chosen during a discharge phase of said battery (BC),A maximum overall discharge power that can be supplied by the latter (BC) is determined as a function of a predefined maximum discharge power of said battery (BC) and a second product of said second maximum overall discharge current determined by a minimum limit voltage of said battery (BC) determined or said optimal minimum voltage.

3. Method according to claim 2, characterized in that in said step (10-40) said overall recharge power limit is determined by choosing a larger value from said first product, and said predefined battery (BC) recharge power limit, and said overall discharge power limit is determined by choosing a smaller value from said second product and said predefined battery (BC) discharge power limit.

4. A method according to any one of claims 1 to 3, characterized in that in said step (10-40) each of said fifth static limiting current for charging said battery (BC) and fifth static limiting current for discharging said battery (BC) is determined as a function of a current state of charge of said battery (BC), a current capacitive health state of said battery (BC), an average internal temperature in said battery (BC), determined from measured cell temperatures of said cells (EC), and from maximum cell temperature and minimum cell temperature determined from said measured cell temperatures.

5. A method according to claim 4, characterized in that in said step (10-40) said fifth static battery charging limiting current (BC) is determined by selecting a smaller value from first, second, and third charging limiting current values ​​determined, respectively, as a function of said mean internal temperature, maximum measured cell temperature, and minimum measured cell temperature, in a first charging table establishing a correspondence between temperatures, states of charge, capacitive health states, and charging limiting current values, and said fifth static battery discharging limiting current (BC) is determined by selecting a larger value from first, second, and third discharging limiting current values ​​determined, respectively, as a function of said mean internal temperature,Maximum measured cell temperature and minimum measured cell temperature, in a second discharge table establishing a correspondence between temperatures, charge states, capacitive health states, and discharge limiting current values.

6. A method according to any one of claims 1 to 5, characterized in that in said step (10-40) maximum cell temperature and minimum cell temperature are determined from among measured cell temperatures of said cells (EC), and each of said first and second thresholds are determined as a function of said maximum cell temperature and minimum cell temperature determined.

7. Product computer program comprising an instruction set which, when executed by processing means, is suitable for implementing the monitoring method according to any one of claims 1 to 6 for monitoring overvoltages and undervoltages of a battery (BC) having optimal maximum and minimum voltages, open-circuit voltage, and limiting internal resistances for charging and discharging, and comprising cells (CE) suitable for

8. store and supply electrical energy and each having a measurable cell voltage. A monitoring device (DS) for monitoring overvoltages and undervoltages of a battery (BC) having optimal maximum and minimum voltages, an open-circuit voltage, and limiting internal resistances for charging and discharging, and comprising cells (CE) suitable for storing and supplying electrical energy and each having a measurable cell voltage, characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to perform the operations of determining maximum and minimum cell voltages among the measured cell voltages, and when said maximum cell voltage plus a first margin voltage is greater than a first chosen threshold during a charging phase of said battery (BC), to determine a first limiting charging current that can supply the latter (BC) as a function of said optimal maximum voltage,open-circuit voltage and internal resistance limit for charging, or when said minimum cell voltage plus a second margin voltage is less than a second threshold chosen during a discharge phase of said battery (BC), to determine a first limit discharge current that can be supplied by the latter (BC) as a function of said optimal minimum voltage, open-circuit voltage and internal resistance limit for charging, and when said maximum cell voltage plus said first margin voltage is greater than said first threshold chosen during a charging phase of said battery (BC), to determine a second overall limit charge current that can supply the latter (BC) as a function of at least said first limit charge current, a third limit charge current resulting from an architecture of said battery (BC), a fourth limit charge current resulting from a limit charge voltage of said battery (BC),and a fifth static limiting current for recharging said battery (BC) determined, or when said minimum cell voltage plus said second margin voltage is less than a second threshold chosen during a discharge phase of said battery (BC), to determine a second overall limiting discharge current that can be supplied by the latter (BC) as a function of at least said first limiting discharge current, of a third, the discharge limit current resulting from said battery architecture (BC), a fourth discharge limit current resulting from a discharge limit voltage of said battery (BC), and a fifth static discharge limiting current of said battery (BC) determined.

9. System (S) comprising a battery (BC) having optimal maximum and minimum voltages, open-circuit voltage and limiting internal resistances for charge and discharge, and comprising cells (CE) suitable for storing and supplying electrical energy and each having a measurable cell voltage, characterized in that it further comprises a monitoring device (DS) according to claim 8.

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