PREVENTIVE MONITORING OF OVERVOLTAGES AND UNDERVOLTAGES OF A CELLULAR BATTERY OF A SYSTEM

Abstract

A method for monitoring overvoltages and undervoltages of a cellular battery, and comprises a step (10-40) in which maximum and minimum cell voltages are determined from among measured cell voltages, and when the maximum cell voltage plus a first margin voltage is greater than a first threshold during a recharging phase, a first recharging limit current that can supply the battery is determined as a function of optimal maximum voltage, no-load voltage and internal recharging limit resistance, or when the minimum cell voltage plus a second margin voltage is less than a second selected threshold during a discharging phase, a first discharging limit current that can be supplied by the battery is determined as a function of optimal minimum voltage, no-load voltage and internal discharging limit resistance. Figure 3

Description

Title of the invention: PREVENTIVE MONITORING OF OVERVOLTAGES AND UNDERVOLTAGES OF 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 can be used at least to supply electrical energy to at least one electric motor forming part of the powertrain (or GMP) and connected to the main power supply (or electrical) circuit. In this case, the cellular battery is generally called "main" (or traction or even power) because it provides electrical energy used for the vehicle's movements.

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

[0005] As is known to those skilled in the art, a cellular battery may sometimes be subject to an undervoltage, in particular in a discharge phase, or an overvoltage, in particular in a recharge phase. Here, the term "overvoltage" is understood to mean a voltage higher than a maximum voltage expected for the cellular battery considered (in particular taking into account its age and its overall state of health). Furthermore, here, the term "undervoltage" is understood to mean a voltage lower than a minimum voltage expected for the cellular battery considered (in particular taking into account its age and its overall state of health).

[0006] An overvoltage or undervoltage is generally significant of a malfunction of the cellular battery, and can cause its premature aging as well as possibly heating which could cause a fire, potentially dangerous for the vehicle and its passengers.

[0007] Since overvoltages and undervoltages of a cellular battery are all the more worrying as the current flowing in the latter is high, they are generally monitored. Generally, when the monitoring device detects an overvoltage or undervoltage for a duration greater than a threshold, the cell battery is decoupled from all electrical machines and the power supply circuit that are 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] A disadvantage of this decoupling lies in the fact that the system suddenly becomes unable to function (which results in immobilization in the case of a vehicle), and therefore it is necessary to call 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 penalizing for the users of this system since they suddenly can no longer use it.

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

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

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

[0012] - maximum cell voltage and minimum cell voltage are determined among the measured cellular voltages, and

[0013] - when this maximum cellular voltage added to a first voltage of margin is greater than a first threshold chosen during a battery recharge phase, a first recharge limit current is determined which can supply the latter according to the optimal maximum voltage, no-load voltage and internal recharge limit resistance, or

[0014] - when the minimum cell voltage added to a second margin voltage is lower than a second threshold chosen during a battery discharge phase, a first discharge limit current is determined which can be supplied by the latter as a function of the optimal minimum voltage, no-load voltage and internal discharge limit resistance.

[0015] Thanks to the invention, it is now possible to prevent the recharge current supplying the cellular battery from being greater than the first determined recharge limit current or 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 cell battery.

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

[0017] - in its step, when the maximum cell voltage added to the first margin voltage is greater than the first threshold chosen during a battery recharge phase, a second overall recharge limit current can be determined which can supply the latter as a function of at least the first recharge limit current, a third recharge limit current resulting from a battery architecture, a fourth recharge limit current resulting from a battery recharge limit voltage, and a fifth determined static battery recharge limitation current.Likewise, when the minimum cell voltage plus the second margin voltage is lower than a second threshold chosen during a battery discharge phase, a second overall discharge limit current can be determined that can be supplied by the latter as a function of at least the first discharge limit current, a third discharge limit current resulting from the architecture of the battery, a fourth discharge limit current resulting from a battery discharge limit voltage, and a fifth determined static battery discharge limitation current;

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

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

[0020] - also in the presence of the first option, in its step, we can determine each of the fifth static battery recharge limiting current and fifth static battery discharge limiting current based on 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, we can determine the fifth static battery recharge limitation current by choosing a smaller value from among first, second and third determined recharge limitation current values, based respectively on the average internal temperature, maximum measured cell temperature and minimum measured cell temperature, in a first recharge table establishing a correspondence between temperatures, states of charge, capacitive health states, and recharge limitation current values.Similarly, the fifth static discharge limiting current of the battery can be determined by choosing a larger value from among first, second and third determined discharge limiting current values, as a function respectively of the average 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, one can determine maximum cell temperature and tem minimum cell temperature among measured cell temperatures of the cells, and each of the first and second selected thresholds may be determined based on these determined maximum cell temperature and minimum cell temperature;

[0023] - in the presence of the last option, in its step, we can determine the first threshold chosen by choosing a smaller value from among first and second threshold values ​​determined, respectively as a function of the maximum measured cell temperature and the minimum measured cell temperature, in a third recharge table establishing a correspondence between maximum and minimum cell temperatures and the first and second threshold values. Similarly, the second threshold chosen can be determined by choosing a larger value from among third and fourth threshold values ​​determined, respectively as a function of the maximum measured cell temperature and the minimum measured cell temperature, in a fourth discharge table establishing a correspondence between maximum and minimum cell temperatures and the third and fourth threshold values.

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

[0025] The invention also provides a monitoring device intended to monitor overvoltages and undervoltages of a battery having optimal maximum and minimum voltages, an open-circuit voltage and internal limit resistances for recharging and discharging, and comprising cells capable of storing and supplying electrical energy and each having a measurable cell voltage.

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

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

[0028] - when this maximum cellular voltage added to a first voltage of margin is greater than a first threshold chosen during a battery recharge phase, to determine a first recharge limit current which can supply the latter according to the optimal maximum voltage, no-load voltage and internal recharge limit resistance, or

[0029] - when the minimum cell voltage added to a second margin voltage is less than a second threshold chosen during a battery discharge phase, to determine a first discharge limit current which can be supplied by the latter as a function of the optimal minimum voltage, no-load voltage and internal discharge limit 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 internal limit resistances for charging and discharging, and comprising cells capable of 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 characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0032] [Fig-1] schematically and functionally illustrates an example of the embodiment of a vehicle comprising a monitoring device according to the invention and a GMP with an electric motor powered by a cellular battery associated with a cal- battery cululator,

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

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

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

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

[0037] Furthermore, it is considered in the following, by way of non-limiting example, that the vehicle S comprises a transmission chain with a powertrain (or GMP) of the all-electric type (and therefore comprising at least one electric motor associated with a cellular battery). But the GMP could be of the hybrid type (and in this case the drive of the vehicle S is provided by at least one thermal motor and one electric motor).

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

[0039] The service battery BS is responsible for supplying electrical energy to the on-board network RB of the vehicle S, in addition to that supplied by the CV converter powered by the cellular battery BC via a main electrical circuit, and sometimes instead of this CV converter. For example, this service battery BS can be arranged in the form of a very low voltage type battery (typically 12 V, 24 V or 48 V). It is rechargeable at least by the CV converter. It is considered in the following, by way of non-limiting example, that the service battery BS is of the type 12V lithium-ion.

[0040] The on-board network RB 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") 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 for example the converter CV and the prime mover MME. It also allows the recharging of the cellular battery BC by an external power source SA temporarily coupled to the vehicle S, for example via a recharging cable CR temporarily connected to a recharging connector CN of the vehicle S.

[0042] The transmission chain has a GMP which is, here, purely electric, and therefore which comprises, in particular, in addition to its (electric) driving machine MME, a motor shaft, and a transmission shaft. Here, the term "electric driving machine" means an electric machine arranged so as to provide engine torque to move the system S (here a vehicle), as well as possibly to recover torque (for example in a regenerative braking phase). The operation of the GMP is supervised by a supervision computer CS.

[0043] The driving machine MME (here an electric motor) is coupled to the cellular battery BC via the main electrical circuit, in order to be supplied with electrical energy, as well as possibly to supply this cellular 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 reducer RD which is also coupled to the transmission shaft, itself coupled to a first train T1 (here of wheels), preferably via a differential DF.

[0044] This first train T1 is here located in the front part PVV of the vehicle S. But in a variant this first train T1 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 driving machine is controlled by a machine computer (not shown), and supervised by the supervision computer CS.

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

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

[0048] The cellular battery BC comprises N cells CE for storing electrical energy, with N > 1. It will be noted that the cells CE can possibly be grouped in modules MC which are identical or different from each other, as illustrated non-limitingly in [Fig.l].

[0049] For example, the CE 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 cellular battery BC can be of low voltage type (typically 450 V for illustration). But it could be of 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 recharge limit resistance Rilr and an internal discharge limit resistance Rild which are known internally (for example by the battery calculator CB).

[0053] Furthermore, the cellular battery BC is (here) associated with a battery box BB which notably comprises the interface (or isolation) device DI, voltage / current measuring means (not illustrated), and a battery calculator CB. The cellular battery BC and the battery box BB can constitute a battery assembly (or “pack”).

[0054] The interface (or isolation) device DI is arranged so as to isolate, if necessary, the cellular battery BC from the electric motor machine MME and more generally from the main electrical circuit. It comprises, 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 battery calculator CB controls the interface device DI. In addition, it centralizes the current measurements, the voltage measurements (in particular those (uc) which are determined by the N voltage sensors (associated respectively with the N cells CE)) and the cell temperature measurements te (which are determined by the N voltage sensors (associated respectively with the N cells CE)), and determines parameters of the cellular battery BC as a function of these measurements, and in particular its minimum voltage Umin and maximum voltage Umax, its current state of charge (or SOC (“State Of Charge”)) socBc and its current capacitive state of health (or SOHC (“State Of Charge”)) State Of Health of Capacity")) soheBc, as well as possibly its current resistive health status (or SOHR ("State Of Health of Resistance")). In addition, the CB battery calculator also exchanges information with the CS supervision calculator of the GMP.

[0056] It will be noted that in the example illustrated non-limitingly in [Fig.l] the vehicle S also comprises a distribution box BD to which the service battery BS, the converter CV and the on-board network RB are coupled. This distribution box BD is responsible for distributing in the on-board network RB the electrical energy which is produced by the converter CV or stored in the service battery BS, for the supply of the electrical components (or equipment) coupled to the on-board network RB, according to power supply requests received (in particular from the supervision computer CS of the GMP).

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

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

[0059] The memory MD is live in order to store instructions for the implementation by the processor PR1 of at least part of the monitoring method. The processor PR1 may comprise integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is understood to mean any type of device capable of carrying out at least one electrical or electronic operation.

[0060] In the example illustrated non-limitingly in Figures 1 and 2, the monitoring device DS is part of the battery computer CB. But it could be part of another computer embedded in the system S and providing at least one other function, or could comprise its own dedicated computer.

[0061] As illustrated non-limitingly 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 cellular battery BC (whether in a recharging phase or in a discharging phase).

[0062] Step 10-40 of the method comprises a sub-step 10 in which one (for example the monitoring device DS) determines a maximum cell voltage ucmax and a minimum cell voltage ucmin among all measured cell voltages uc.

[0063] Step 10-40 of the method then comprises a sub-step 20 which concerns both a phase of recharging the battery BC and a phase of discharging the cellular battery BC.

[0064] In this sub-step 20, when the maximum cellular voltage ucmax added to a first margin voltage ulm is greater than a first threshold chosen si (i.e. ucmax + ulm > si), there is an overvoltage or quasi-overvoltage situation. In this case, one (for example the monitoring device DS) determines a first recharge limit current Illr that can supply the cellular battery BC, as a function of the optimal maximum voltage Umaxo, the no-load voltage UOCV and the internal recharge limit resistance Rilr. Thus, it is prevented in a preventive manner that the recharge current supplying the cellular battery BC is greater than the first determined recharge limit current Illr, to avoid the occurrence of a possible overvoltage. This advantageously makes it possible to avoid decoupling of the cellular battery BC, and therefore to increase the availability of the latter (BC).

[0065] Still in sub-step 20, when the minimum cell voltage ucmin added to a second margin voltage u2m is lower than a second chosen threshold s2 (i.e. ucmin + u2m < s2), there is an undervoltage or quasi-undervoltage situation. In this case, one (for example the monitoring device DS) determines a first discharge limit current Illd that can be supplied by the cell battery BC, as a function of the optimal minimum voltage Umino, the no-load voltage UOCV and the internal discharge limit resistance Rild. Thus, it is prevented in a preventive manner that the discharge current supplied by the cell battery BC is greater than the first determined discharge limit current Illd, to avoid the occurrence of a possible undervoltage. This advantageously makes it possible to avoid decoupling of the cell battery BC, and therefore to increase the availability of the latter (BC).

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

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

[0068] [Math.l] Illr = min(0, )

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

[0070] [Math.2] i ita — max iu, ----i

[0071] Preferably, the first recharge limit current Illr is determined only on condition that the maximum cellular voltage ucmax plus the first margin voltage ulm is greater than the first chosen threshold if 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 discharge limit current Illd is only determined on condition that the minimum cell voltage ucmin plus the second margin voltage u2m is lower than the second chosen threshold s2 for at least the first chosen duration.

[0073] Also for example, in sub-step 10 of step 10-40, one (for example the monitoring device DS) can also determine a maximum cell temperature tcmax and a minimum cell temperature tcmin among the measured cell temperatures te of the CE cells. In this case, in this sub-step 10 one (for example the monitoring device DS) 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 monitoring device DS) can, for example, determine the first threshold si by choosing the smallest value among first vsl and second vs2 threshold values ​​determined in a (third) recharge table (or mapping) tr3 establishing a correspondence between maximum and minimum cell 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 recharge table tr3 as a function respectively of the maximum cell temperature tcmax measured and the minimum cell temperature tcmin measured. We then have si = min(vsl, vs2).

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

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

[0077] It will be noted that in a recharging phase, when a limitation (Illr) of the recharging current has been determined, it is possible to stop this limitation when the maximum cell voltage ucmax added to the first margin voltage ulm becomes lower than 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, one (for example the monitoring device DS) performs step 10-40 of the method again with new measurements of the cell voltages uc but without limitation of the recharging current. For example, the second chosen duration can be between 150 ms and 250 ms.

[0078] Similarly, in a discharge phase, when a limitation (Illd) of the discharge current has been determined, it is possible to stop this limitation when the minimum cell voltage ucmin added to the second margin voltage u2m becomes lower than 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, one (for example the monitoring device DS) performs step 10-40 of the method again with new measurements of the cell voltages uc but without limitation of the discharge current.

[0079] It will be noted that in sub-step 10 one (for example the monitoring device DS) 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 monitoring device DS) can, for example, determine the third threshold s3 by choosing the smallest value among the fifth vs5 and sixth vs6 threshold values ​​determined in a fifth recharge table (or mapping) tr5 establishing a correspondence between maximum and minimum cell temperatures and fifth and sixth threshold values. It will be understood that these fifth vs5 and sixth vs6 threshold values ​​are determined in the fifth recharge table tr5 as a function of the temperature respectively maximum cell temperature tcmax measured and minimum cell temperature tcmin measured. We then have s3 = min(vs5, vs6).

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

[0082] In an alternative 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 method may also comprise a sub-step 30 in which one (for example the monitoring device DS) may determine a second overall recharge limit current I21rg capable of supplying the cellular battery BC or a second overall discharge limit current I21dg capable of being supplied by the cellular battery BC. These second overall recharge limit current I21rg and second overall discharge limit current I21dg are intended to take into account all the constraints of the battery assembly, including those called architectural (connectors, cables and series and / or parallel assemblies) and the current limitations (linked to the chemistry of the cellular battery BC), unlike the first recharge limit current Illr and first discharge limit current Illd which essentially only take into account the voltage and possibly temperature constraints.

[0084] In this sub-step 30, when the maximum cellular voltage ucmax added to the first margin voltage ulm is greater than the first threshold if chosen during a recharging phase of the cellular battery BC, one (for example the monitoring device DS) can determine the second overall recharging limit current I21rg as a function of at least the first recharging limit current Illr, a third recharging limit current I31r resulting from the architecture of the battery BC, a fourth recharging limit current I41r resulting from a recharging limit voltage of the cellular battery BC, and a fifth static recharging limitation current I51sr of the determined cellular battery BC.

[0085] Still in sub-step 30, when the minimum cell voltage ucmin added to a second margin voltage u2m is lower than the second chosen threshold s2 during a discharge phase of the cell battery BC, one (for example the monitoring device DS) can determine the second discharge limit current global 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 limitation current I51sd of the cell battery BC determined.

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

[0087] The parameters rl and r2 are weighting coefficients which can be either always equal to one (and therefore fixed), or 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 monitoring device DS) can determine the variable parameter rl using the following equation:

[0089] [Math.3] rl= rcl-max^O, minores], ^Ki^Uerrïjdt^ )

[0090] where rcl is a maximum value in recharge which can be between 0 and 1, rcsl is a maximum correction value in recharge 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 sub-step 30, one (for example the monitoring device DS) can determine the variable parameter r2 using the following equation:

[0092] [Math.4] r2 = rc2-max^0, min^rcs2, \(Ki*Uerr2)dt^ j

[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 equal to 0.005), and Uerr2 is equal to (ucmin - s2).

[0094] Also for example, and as illustrated non-limitingly in [Fig.3], step 10-40 of the method can also comprise a sub-step 40 in which one (for example the monitoring device DS) can determine an overall recharge limit power Plrg that can be supported by the cellular battery BC or an overall discharge limit power Pldg that can be provided by the cellular battery BC.

[0095] In this sub-step 40, when the maximum cellular voltage ucmax added to the first margin voltage ulm is greater than the first threshold chosen if, and therefore when there is an overvoltage or quasi-overvoltage situation, one (for example the monitoring device DS) can determine the overall recharge limit power Plrg that can be supported by the cellular battery BC, as a function of a predefined (and therefore fixed) recharge limit power Plr of the cellular battery BC and of a first product pl of the second overall recharge limit current I21rg determined by a determined maximum limit voltage Umaxl of the cellular battery BC or the optimal maximum voltage Umaxo. Thus, it is also prevented in a preventive manner that the recharge power supported by the cellular battery BC is greater than the determined overall recharge limit power Plrg, to further avoid the occurrence of a possible overvoltage.This advantageously makes it possible to further avoid decoupling of the BC cell battery, and therefore to increase the availability of the latter (BC).

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

[0097] Similarly, in this sub-step 40, when the minimum cell voltage ucmin added to the second margin voltage u2m is lower than the second threshold s2 chosen during a discharge phase of the cell battery BC, one (for example the monitoring device DS) can determine the overall discharge limit power Pldg that can be supplied by the cell battery BC as a function of a predefined (and therefore fixed) 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, it is also prevented in a preventive manner that the discharge power supplied by the cell battery BC is greater than the determined overall discharge limit power Pldg, to further avoid the occurrence of a possible undervoltage.This advantageously makes it possible to further avoid decoupling of the BC cell battery, and therefore to increase the availability of the latter (BC).

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

[0099] It will be noted that in sub-step 40 one (for example the monitoring device DS) can, for example, determine the overall recharge limit power Plrg by choosing the largest value from the first product pl and the limit power of Plr recharge of the predefined BC cell battery (i.e. Plrg = max(pl, Plr)). It is recalled that pl can be equal either to I21rg*Umaxl or to I21rg*Umaxo.

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

[0101] Also for example, in sub-step 30 one (for example the monitoring device DS) can determine each of the fifth static recharge limiting current I51sr of the cell battery BC and fifth static discharge limiting current I51sd of the cell battery BC as a function of the current state of charge socBc of the cell battery BC, the current capacitive health state sohcBc of the cell battery BC, an average internal temperature timBC in the cell battery BC, and the maximum cell temperature tcmax and minimum cell temperature tcmin. It will be noted that the average internal temperature timBC is determined from all the measured cell temperatures te of the cells CE, 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 sub-step 40 one (for example the monitoring device DS) can, for example, determine the fifth static recharge limitation current I51sr of the cellular battery BC by choosing the smallest value among the first vilrl, second vilr2 and third vilr3 recharge limitation current values ​​determined in a first recharge table (or mapping) tri establishing a correspondence between temperatures, states of charge, capacitive health states and recharge limitation current values. It will be noted that this determination of the first vilrl, second vilr2 and third vilr3 limitation current values ​​is done in the first recharge table tri, as a function respectively of the average internal temperature timBC, maximum cell temperature tcmax measured and minimum cell temperature tcmin measured. We then have I51sr = min(vilrl, vilr2, vilr3).

[0103] Similarly, in sub-step 40 one (for example the monitoring device DS) can, for example, determine the fifth static discharge limitation current I51sd of the cellular battery BC by choosing the largest value among first vildl, second vild2 and third vild3 discharge limitation current values ​​determined in a second discharge table (or mapping) tr2 establishing a correspondence between temperatures, states of charge, capacitive health states and discharge limitation current values. It will be noted that this determination of the first vildl, second vild2 and third vild3 discharge limitation current values limiting current is done in the second recharge table td2, depending respectively on the average internal temperature timBC, maximum cell temperature tcmax measured and minimum cell temperature tcmin measured. We then have I51sd = min(vildl, vild2, vild3).

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

[0105] It will 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 of the electronic circuit (or hardware) type, such as for example the processor PR1, is capable of implementing the monitoring method described above to preventively monitor, in the system S, the overvoltages and undervoltages of the cellular battery BC.

Claims

Claims

1. Method for monitoring overvoltages and undervoltages of a battery (BC) having optimal maximum and minimum voltages, an open-circuit voltage and internal limit resistances for recharging and discharging, and comprising cells (CE) capable of storing and supplying electrical energy and each having a measurable cell voltage, characterized in that it comprises a step (10-40) in which maximum cell voltage and minimum cell voltage are determined from among the measured cell voltages, and when said maximum cell voltage plus a first margin voltage is greater than a first threshold chosen during a recharging phase of said battery (BC), a first limit recharging current capable of supplying the latter (BC) is determined as a function of said optimal maximum voltage, open-circuit voltage and limit internal recharging resistance,or when said minimum cell voltage plus a second margin voltage is lower than a second threshold chosen during a discharge phase of said battery (BC), a first discharge limit current that can be supplied by the latter (BC) is determined as a function of said optimal minimum voltage, no-load voltage and internal discharge limit resistance.,

2. Method according to claim 1, characterized in that in said step (10-40), when said maximum cell voltage added to said first margin voltage is greater than said first threshold chosen during a recharging phase of said battery (BC), a second overall recharging limit current capable of supplying the latter (BC) is determined as a function of at least said first recharging limit current, a third recharging limit current resulting from an architecture of said battery (BC), a fourth recharging limit current resulting from a recharging limit voltage of said battery (BC), and a fifth determined static recharging limitation current of said battery (BC), or when said minimum cell voltage added to said second margin voltage is lower than a second threshold chosen during a discharging phase of said battery (BC),a second overall discharge limit current that can be supplied by the latter (BC) is determined as a function of at least said first discharge limit current, a third discharge limit current resulting from said architecture of the battery (BC), a, fourth discharge limit current resulting from a discharge limit voltage of said battery (BC), and from a fifth static discharge limitation current of said battery (BC) determined.

3. Method according to claim 2, characterized in that in said step (10-40), when said maximum cell voltage added to said first margin voltage is greater than said first threshold chosen during a recharging phase of said battery (BC), an overall recharging limit power that can be supported by the latter (BC) is determined as a function of a predefined recharging limit power of said battery (BC) and a first product of said second overall recharging limit current determined by a determined maximum limit voltage of said battery (BC) or said optimal maximum voltage, or when said minimum cell voltage added to said second margin voltage is lower than a second threshold chosen during a discharging phase of said battery (BC),an overall discharge limit power that can be supplied by the latter (BC) is determined as a function of a predefined discharge limit power of said battery (BC) and a second product of said second overall discharge limit current determined by a minimum limit voltage of said battery (BC) determined or said optimal minimum voltage.,

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

5. Method according to one of claims 2 to 4, characterized in that in said step (10-40) each of said fifth static recharge limitation current of said battery (BC) and fifth static discharge limitation current of said battery (BC) is determined as a function of a current charge state 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 (CE), and maximum cell temperature and minimum cell temperature determined from among said measured cell temperatures.

6. Method according to claim 5, characterized in that in said step (10-40) said fifth static battery recharge limitation current (BC) is determined by choosing a smaller value from among first, second and third determined recharge limitation current values, as a function respectively of said average internal temperature, measured maximum cell temperature and measured minimum cell temperature, in a first recharge table establishing a correspondence between temperatures, states of charge, capacitive health states, and recharge limitation current values, and said fifth static battery discharge limitation current (BC) is determined by choosing a larger value from among first, second and third determined discharge limitation current values, as a function respectively of said average internal temperature, measured maximum cell temperature and measured minimum cell temperature,in a second discharge table establishing a correspondence between temperatures, states of charge, capacitive health states, and discharge limiting current values.,

7. Method according to one of claims 1 to 6, 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 (CE), and each of said first and second thresholds chosen is determined as a function of said determined maximum cell temperature and minimum cell temperature.

8. Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the monitoring method according to one of claims 1 to 7 for monitoring overvoltages and undervoltages of a battery (BC) having optimal maximum and minimum voltages, an open-circuit voltage and internal limit resistances for recharging and discharging, and comprising cells (CE) capable of storing and supplying electrical energy and each having a measurable cell voltage.

9. Monitoring device (DS) for monitoring overvoltages and undervoltages of a battery (BC) having optimum maximum and minimum voltages, an open-circuit voltage and internal limit resistances for recharging and discharging, and comprising cells (CE) capable of 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 for performing the operations of determining maximum cell voltage and minimum cell voltage among the measured cell voltages, and when said maximum cell voltage plus a first margin voltage is greater than a first threshold chosen during a recharging phase of said battery (BC), determining a first limit recharging current capable of supplying the latter (BC) as a function of said optimal maximum voltage, no-load voltage and limit internal recharging resistance, 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), determining a first limit discharging current capable of being supplied by the latter (BC) as a function of said optimal minimum voltage, no-load voltage and limit internal discharging resistance.

10. System (S) comprising a battery (BC) having optimum maximum and minimum voltages, an open-circuit voltage and internal limit resistances for charging and discharging, and comprising cells (CE) capable of 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 9.

Images