ACCURATE ESTIMATION OF INFORMATION RELATING TO A CELLULAR BATTERY

Abstract

A method makes it possible to estimate at least one piece of information relating to a cellular battery of a system comprising N cells storing electrical energy, with N > 1, and each having a current resistive state of health and / or a current capacity state of health. This method comprises a step (10-40) in which a final state of charge is estimated for each cell after a discharge as a function of its current resistive state of health and / or its current capacity state of health, then a first piece of information representative of the total energy available in the cellular battery is estimated as a function of these estimated final states of charge and respective initial states of charge of the cells after a complete recharge. Figure 3

Description

Title of the invention: ACCURATE ESTIMATION OF INFORMATION RELATING TO A BATTERY CELLULAR Technical field of the invention

[0001] The invention relates to cellular batteries, and more precisely to the estimation of information relating to such batteries. State of the art

[0002] In many fields, cellular batteries are used to store electrical energy intended to power at least one electrical machine (possibly a motor machine) and / or an electrical power supply circuit. This is the case, for example, although not limited to, in the field of vehicles (possibly of the automobile type).

[0003] Some of these cellular batteries comprise at least two electrical energy storage cells, possibly electrochemical (for example of the lithium-ion (or Li-ion) or Ni-Mh or Ni-Cd type). It will be noted that in the case of a vehicle, the cellular battery may be a so-called "main" battery (or traction or even power) because it is responsible for supplying electric current to an on-board network, via a converter, and to an electric motor of the powertrain (or GMP), or a so-called "service" battery because it is of the very low voltage type (typically between 12 V and 48 V) and responsible for supplying electric current to the on-board network in the absence of a main battery (and therefore an electric motor) or instead of or in addition to the main battery.

[0004] In the following and the preceding, the term "on-board network" means an electrical supply network to which electrical (or electronic) equipment (or components) consuming electrical energy are coupled.

[0005] Current cellular batteries are subject to management of certain of their parameters in order to be able to be used optimally, with a minimized risk of failure and incident, for example for the safety and peace of mind of the users of their vehicles. This management allows in particular the carrying out of diagnostics intended to optimize the use of the cellular battery, to reduce the costs of repairs and to anticipate a major malfunction.

[0006] Among the parameters managed, we can notably cite the total energy available in the cellular battery (or UBE (“Useful Battery Energy”)) and its derivatives such as for example the energy state of health of the cellular battery (or SOHE (“State Of Health of Energy") - also called State of Certified Energy (or SOCE ("State Of Certified Energy")). It is recalled that these derivatives are, for example and in particular, used to estimate the autonomy of a vehicle as precisely as possible so as not to overestimate or underestimate performance.

[0007] It has been proposed, in particular in patent document FR-A1 3130039, to estimate the information representative of the total energy available in the cellular battery as a function of the current states of charge (SOH (“State Of Health”)), current resistive states of health (or SOHR (“State Of Health of Resistance”)), current capacity states of health (or SOHC (“State Of Health of Capacity”)), and a time interval during which the cellular battery is allowed to discharge under a chosen discharge current and at a reference temperature.

[0008] It is recalled that the current resistive health status (or SOHR) of a cell increases with aging and therefore its impact on energy dissipation increases.

[0009] The method of estimating the information representative of the total energy available in the cellular battery, presented above, offers fairly good results. However, the developments in certain national or international standards require that the level of precision on the total energy available in the cellular battery (or UBE) and its derivative (energy health status (or SOHE) or certified energy status (or SOCE)) be ever greater. However, the aforementioned estimation method does not allow such a level of precision to be achieved. This results from the fact that it does not take into account the initial charge imbalances (after a full charge) between cells.It uses either a fixed starting value for each initial state of charge (after full recharge) for each cell, or a fixed amount of x% protection energy which is subtracted from the initial state of charge so as not to overestimate the performance of the cell battery in terms of total available energy and to protect against an overestimation of the total available energy. It will be understood that this does not allow the imbalance (or deviation) to be correctly quantified on a case-by-case basis and, above all, does not allow cases where an imbalance (or deviation) is higher and therefore may lead to an overestimation of the total available energy to be covered.

[0010] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0011] It proposes in particular for this purpose a method for estimating information(s), on the one hand, intended to be implemented in a system comprising a cellular battery comprising N cells capable of storing electrical energy, with N > 1, and each having a current resistive health state (or SOHR) and a current capacity health state (or SOHC), and, on the other hand, comprising a step in which a final state of charge is estimated for each cell after a discharge as a function of the health state current resistive and / or current capacity health status.

[0012] This method of estimating information(s) is characterized by the fact that in its step a first piece of information representative of a total energy available in the cellular battery is also estimated as a function of the estimated final charge states and respective initial charge states of the cells after a complete recharge.

[0013] Thanks to this consideration not only of the final charge states, but also of the initial charge states, it is now possible to estimate in the system, in a very precise and very reliable manner, a first piece of information which is representative of the total energy available in the cellular battery, which in particular makes it possible to comply with the high levels of precision imposed by the developments of certain national or international standards.

[0014] The method for estimating information(s) according to the invention may include other characteristics which may be taken separately or in combination, and in particular:

[0015] - in a first embodiment, in its step, it is possible to use for each cell an initial state of charge which is chosen from an estimated current state of charge just after full recharge and a value depending on an ampere-hour quantity to be balanced in the cell concerned and a smallest state of charge from all the current states of charge of the cells after full recharge and a complete relaxation phase of the cell battery;

[0016] - in a second embodiment, in its step, the state of initial charge of each cell based on an estimated current state of charge of the latter after full recharging and a complete relaxation phase of the cell battery, an initial electrical energy storage capacity of the cell concerned, and a target maximum state of charge for the end of charging for each cell concerned;

[0017] - in this second embodiment, in its step, it is possible to estimate for each cell the current state of charge after full recharge and the full relaxation phase of the cell battery, then, when this estimated current state of charge is between first and second chosen thresholds, an amount of ampere-hours to reach the target maximum state of charge can be determined based on the estimated current state of charge of this cell, the target maximum state of charge and the initial electrical energy storage capacity of the cell concerned, then a smaller amount of ampere-hours to reach the target maximum state of charge can be determined from among all the amounts of ampere-hours to reach the target maximum state of charge determined for the cells, then the initial state of charge of each cell can be determined based on the estimated current state of charge of the latter,of the smallest amount of ampere-hours to achieve the determined target maximum state of charge and the initial electrical energy storage capacity of , the cell concerned;

[0018] - in a third embodiment, in its step, the state of initial charge of each cell based on an estimated current state of charge of the latter after full recharge and a complete relaxation phase of the cell battery, an initial electrical energy storage capacity of the cell concerned, a target maximum state of charge for an end of charge for each cell concerned, and a smallest state of charge among all the current states of charge of the cells after full recharge and a complete relaxation phase of the cell battery;

[0019] - in this third embodiment, in its step, it is possible to determine for each cell an amount of ampere-hours to be balanced based on the estimated current state of charge of that cell, the smallest determined state of charge and the initial electrical energy storage capacity of that cell, then, when the state of charge of a cell is greater than a third chosen threshold, a state of charge deviation can be determined for that cell based on the amount of ampere-hours to be balanced determined and the initial electrical energy storage capacity of that cell, then a largest state of charge deviation can be determined from among all the determined state of charge deviations of the cells, then the initial state of charge of each cell can be determined based on the target maximum state of charge, the largest determined state of charge deviation and the determined state of charge deviation of that cell;

[0020] - alternatively, in this third embodiment, in its step, it is possible to to complete for each cell a quantity of ampere-hours to be balanced according to the estimated current state of charge of this cell, the smallest determined state of charge and the initial electrical energy storage capacity of this cell, then, when the state of charge of a cell is lower than a fourth chosen threshold, a minimum state of charge can be determined for this cell according to the quantity of ampere-hours determined and the initial electrical energy storage capacity of the cell concerned, then a quantity of ampere-hours can be determined to reach the target maximum state of charge according to the minimum determined state of charge of this cell, the target maximum state of charge and the initial electrical energy storage capacity of this cell,then a smallest amount of ampere-hours to reach the target maximum state of charge can be determined from among all the determined amounts of ampere-hours to reach the target maximum state of charge of the cells, then the initial state of charge of each cell can be determined based on the determined minimum state of charge of that cell, the smallest amount of ampere-hours to reach the determined target maximum state of charge and the initial electrical energy storage capacity of that cell; ,

[0021] - in its step we can also estimate a second information representative of a certified energy status of the cell battery based on the first information and total useful energy at the beginning of the cell battery life.

[0022] The invention also proposes a computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing a method for estimating information(s) of the type presented above for estimating at least one item of information relating to a cellular battery of a system comprising N cells capable of storing electrical energy, with N > 1, and each having a current resistive health state and / or a current capacity health state.

[0023] The invention also proposes a device for estimating information(s), on the one hand, intended to equip a system comprising a cellular battery comprising N cells capable of storing electrical energy, with N > 1, and each having a current resistive health state and / or a current capacity health state, and, on the other hand, comprising at least one processor and at least one memory arranged to carry out the operations consisting of estimating for each cell a final state of charge after a discharge as a function of the current resistive health state and / or the current capacity health state.

[0024] This information estimation device is characterized by the fact that its processor and memory are also arranged to carry out the operations consisting of estimating a first piece of information representative of a total energy available in the cellular battery as a function of the estimated final charge states and respective initial charge states of the cells after a complete recharge.

[0025] The invention also proposes a system comprising, on the one hand, a cellular battery comprising N cells capable of storing electrical energy, with N > 1, and each having a current resistive health state and / or a current capacity health state, and, on the other hand, a device for estimating information of the type presented above. Brief description of the figures

[0026] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0027] [Fig-1] schematically and functionally illustrates an example of the embodiment of a vehicle comprising a GMP with an electric motor powered by a cellular battery associated with a battery calculator, and a device for estimating information according to the invention,

[0028] [Fig.2] schematically and functionally illustrates an example of the embodiment of a battery calculator comprising a device for estimating information(s) according to the invention, and

[0029] [Fig.3] schematically illustrates an example of an algorithm implementing a method for estimating information(s) according to the invention. Detailed description of the invention

[0030] The invention aims in particular to propose a method for estimating information(s), and an associated device for estimating information(s) DEI, intended to allow a very precise and very reliable estimation of at least one item of information relating to a cellular battery BC of a system S comprising at least two cells CE.

[0031] 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 relates in fact to any type of system comprising at least one rechargeable cellular battery whatever the mode. 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), fixed or stationary installations (possibly industrial), such as for example electrical energy supply installations, and buildings, for example. By way of purely illustrative example, the cellular battery BC of a system S can be connected to a renewable energy source (in particular photovoltaic or wind).

[0032] Furthermore, it is considered in the following, by way of non-limiting example, that the system S (here a vehicle) comprises a powertrain (or GMP) of the all-electric type (and therefore whose drive is provided exclusively by at least one electric motor MME). But the GMP could be of the hybrid type (thermal and electric) or purely thermal.

[0033] Furthermore, it is considered in the following, by way of non-limiting example, that the cellular battery BC is a main battery (or traction or even power). But the cellular battery which is the subject of the information estimates could be a service battery (possibly rechargeable via a converter supplied with electrical energy by a main battery).

[0034] [Fig.l] schematically shows a system S (here a vehicle) comprising an electric GMP transmission chain, an on-board network RB, a power supply group comprising a service battery BS and (here) a converter CV associated with a cellular battery BC (itself associated with a battery calculator CB), and a device for estimating information(s) DEI according to the invention.

[0035] The on-board network RB is an electrical supply network to which are coupled electrical (or electronic) equipment (or parts) that consume electrical energy.

[0036] The service battery BS is responsible for supplying electrical energy to the on-board network RB, in addition to that supplied by the CV converter powered by the cellular battery BC, and sometimes instead of this CV converter (in particular when the GMP is asleep and the CV converter is inactive). 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 12 V Lithium-ion type.

[0037] The transmission chain has a GMP which is, here, purely electric, and therefore which comprises, in particular, an electric driving machine MME, a motor shaft AM, and a transmission shaft AT. Here, the term “electric driving machine” means an electric machine arranged so as to provide or recover torque to move the system S (here a vehicle). The operation of the GMP is supervised by a supervision computer CS.

[0038] The electric motor MME (here an electric motor) is coupled to the cellular battery BC, in order to be supplied with electrical energy, as well as possibly to supply this cellular battery BC with electrical energy (for example during a regenerative braking phase). It is coupled to the motor shaft AM, to provide it with torque by rotational drive. This motor shaft AM is here coupled to a reducer RD which is also coupled to the transmission shaft AT, itself coupled to a first train T1 (here of wheels), preferably via a differential DI.

[0039] 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.

[0040] The driving machine MME is, here, also coupled to the converter CV which is also indirectly coupled to the service battery BS, in particular to recharge it with electrical energy from the cellular battery BC and converted.

[0041] This CV converter is a current converter electrically coupled, here, to a CN charging connector of the vehicle S, for example. It is also responsible for supplying the on-board network RB with electrical energy from the cellular battery BC and converted when the GMP is in operation or when the GMP is asleep but the vehicle S is in a phase of recharging its cellular battery BC, in addition to ensuring the recharging of the service battery BS.

[0042] In the example illustrated non-limitingly in [Fig.l] the cellular battery BC is suitable not only for recharging in mode 2 or 3, but also for recharging in mode 4.

[0043] For example, the cellular battery BC may comprise N electrochemical electrical energy storage cells CE, with N > 1. Also for example, each cell (electrochemical electrical energy storage) CE may be of the lithium-ion (or Li-ion) type. But this is not obligatory. Indeed, it could be of the Ni-Mh or Ni-Cd type, for example. Also for example, the cellular battery BC may be of the low voltage type (typically 450 V for illustrative purposes). But it could be of the medium voltage or high voltage type.

[0044] It will be noted, as illustrated non-limitingly in [Fig. 1], that the N cells CE may be part of modules MC which are coupled together, for example in series, within the cell battery BC. Here, the term “module MC” means a group of at least one cell CE. When an MC module comprises several cells CE, the latter (CE) may be coupled together in series and / or in parallel.

[0045] It will also be noted that the cellular battery BC is associated with a battery box BB which notably comprises means for measuring voltage, current and internal temperature (not illustrated) and the battery calculator CB. The latter (CB) centralizes the current measurements, the voltage measurements and the internal temperature measurements (notably those which individually concern each of the N cells CE), and estimates parameters of the cellular battery BC as a function of these measurements, and notably its internal resistance, its minimum voltage and its current state of charge (or SOC) SOC;. In the following, “i” is an index which designates each of the N cells CE, and therefore which takes values ​​between 1 and N.

[0046] It will also be noted that in the example illustrated non-limitingly in [Fig. 1] 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).

[0047] As mentioned above, the invention proposes in particular a method for estimating information intended to allow a very precise and very reliable estimation of at least a first piece of information ibl relating to the cellular battery BC.

[0048] This method (of estimating information) can be implemented at least partially by the information estimation device DEI (illustrated in figures 1 and 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 information estimation device DEI can therefore be produced in the form of a combination of electrical or electronic circuits or components (or "hardware") and software modules (or “software”).

[0049] The memory MD is RAM in order to store instructions for the implementation by the processor PR1 of at least part of the information estimation 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.

[0050] In the example illustrated non-limitingly in Figures 1 and 2, the information estimation device DEI is part of the battery calculator CB (and therefore, here, of the battery box BB). But this is not obligatory. Indeed, the information estimation device DEI could comprise its own dedicated calculator, which can then be coupled to the battery calculator CB.

[0051] As illustrated non-limitingly in [Fig. 3], the method (for estimating information(s)), according to the invention, comprises a step 10-40 which is implemented in the system S (here a vehicle) each time that an estimation of at least a first piece of information ibl, representative of the total energy Etotref available in the cellular battery BC, is requested, for example by the battery calculator CB.

[0052] This step 10-40 comprises a sub-step 20 in which one (for example the information estimation device DEI) estimates for each cell CE a final state of charge SOCfin,i after a discharge as a function of its current resistive state of health SOHRi and / or its current capacity state of health SOHC;.

[0053] Step 10-40 also comprises a sub-step 30 in which one (for example the information estimation device DEI) estimates the first information ibl as a function of the estimated final states of charge SOCfin,i of the N cells CE, and of respective initial states of charge SOCini,i of the N cells CE after a complete recharge of the cellular battery BC.

[0054] Thanks to this consideration not only of the final states of charge SOCfin,i, estimated from the parameters SOHR; and / or SOHC;, but also of the initial states of charge SOCini,i, it is now possible to estimate in the system S, in a very precise and very reliable manner, the first information ibl (representative of the total energy Etotref available in the cellular battery BC). This makes it possible in particular to respect the high levels of precision imposed by the evolutions of certain national or international standards.

[0055] It will be understood that it is at least the processor PR1 and memory MD of the estimation device DEI which are arranged to carry out the operations consisting of estimating for each cell CE a final state of charge SOCfin,i after a discharge as a function of its current resistive state of health SOHR; and / or its current capacity state of health SOHCi, then estimating the first information ibl as a function of the estimated final states of charge SOCfinj of the N CE cells, and respective initial states of charge SOCinij of the N CE cells after a full recharge of the cell battery BC.

[0056] It will be noted that step 10-40 may also comprise a preliminary sub-step 10 in which all the resistive health states SOHR;, health states in capacity SOHC; and charge states SOC; are estimated from the voltage, current and internal temperature measurements of each of the cells CE (i). It is recalled that each health state in capacity SOHC; can be estimated from the charge state SOC;, that each resistive health state SOHR; can be estimated from the charge state SOC; and the associated internal temperature, and that each charge state SOC; can be estimated from previous estimates of the resistive health state SOHR; and the health state in capacity SOHC; within a feedback loop.

[0057] The resistive health states SOHR; and / or capacity health states SOHC; and / or charge states SOC; can be estimated by the information estimation device DEI or by the battery calculator CB.

[0058] For example, the first information ibl can be determined by means of the following equation when it is equal to the total energy available for the discharge Etotref •

[0059] [Math.l] _i=Nr fSOCfilü v J ibl = capa^L^HC^,^ dSOC-U^TeSOHR;^ ^Bo^+RmefBOL OW]

[0060] where:

[0061] - CapaBOL * SOHCi = capai, SOHR; * (Ro,TrefBOL,i + Rl.TrefBOL,i) = (Ro,i + Rl,i)»

[0062] - Te is the sampling period equivalent to the call frequency of the function for calculating the first information ibl in the information estimation device DEI, and for example equal to 100 ms or 1 s,

[0063] - Ro.TrefBOLj is the no-load resistance of the circuit which represents the cell CE (i) at the tem reference temperature Tref and at the start of the cell's life CE (i),

[0064] - Ri,Trefbol,i is the internal resistance of the CE cell (i) at the reference temperature Tref and at the beginning of the life of the CE cell (i),

[0065] - OCVi(SOCi) is the open-circuit voltage of the cell CE (i) in the presence of a state of SOC charge;,

[0066] -[Math 2] At^n is a first theoretical time interval that can be determined as a function of a minimum limiting voltage Ucutoff_min, the current electrical energy storage capacities capa; of each of the CE cells, a chosen discharge current Idc, chosen theoretical models (representative respectively of the equivalent resistances R; of each of the CE cells), and the initial charge states SOCini,i of each of the CE cells.

[0067] The definition of the no-load voltage OCVi(SOCi) results here from a theoretical model called “RC” which represents each cell CE within an RC circuit, and in which the voltage U; at the terminals of the cell CE (i) is given by the following equation U; = OCV; (SOCD + R^U

[0068] It will be noted that the open-circuit voltage can be given by the following equation:

[0069] [Math.3] ocvx sœy=œv(socini, , where tini is the initial instant of discharge start and tfin is the final instant of discharge end.

[0070] More complex theoretical models than the RC model can be used, such as for example a theoretical model in which a combination of at least two RC circuits connected in parallel is used for each cell CE (i), instead of a single RC circuit.

[0071] Also for example, each final state of charge SOCfinj can be determined by means of the following equation:

[0072] [Math.4] A t SOCf in, i = SOCini, i

[0073] Each integral can be calculated numerically. In a first variant, the result of each integral can be found in a previously determined map giving the no-load voltage OCVi as a function of the state of charge SOC;. In a second variant, the result of each integral can be found using the trapezoid method, or any equivalent method known to those skilled in the art.

[0074] The equation for ibl, given above, follows from the fact that the total available energy E tot (for the current operating temperature of the cell battery BC) is given by the general equation:

[0075] [Math.5] = J«Uidt = C^CoCVlt), dt - «MO + R,.^)) dt]

[0076] which can be rewritten as follows:

[0077] [Math.6] Zi=N[ .-SOCfinJ fAtfin 1 cWsociniiÛCVrCSOC) dSOC-I^ (R01 + Rv)dt L i=l L ' 'J

[0078] where [Math 7]

[0079] dt = ^xdSOC *dc

[0080] this last equation can in turn be rewritten as follows:

[0081] [Math. 8] Ei=N rSOCfinJ capaj soeinu OCV,(SOC) dSOC - I^TeL^ / R + )= 1 MO

[0082] then as follows:

[0083] [Math.9] ii=N fSOCfin.i ^2!^ capaBo^SOHCj^OCV^SOC) dSOC - Idc2Te.L^SOHR^ BOL1 + R^ol,.

[0084] It will be understood that the transition from Etot to Etotref is done by replacing SOCiniJ by SOCmax,i in the integral because we are referring to the maximum energy at the beginning of life of the cell CE (i), and (R0,BOL,i + Ri,BOL,i) by (Ro,TrefBOL,i + Ri,TrefBOL,i) because we are at the reference temperature Tref.

[0085] At least three embodiments can be envisaged for determining the initial charge states SOCini,i.

[0086] In a first embodiment, in sub-step 20 of step 10-40 one (for example the information estimation device DEI) can choose the initial state of charge SOCiniJ of each cell CE from its current state of charge SOC; estimated just after complete recharging and a value AHeq; which is a function of a quantity of ampere-hours to be balanced in the cell CE concerned and of a smallest state of charge SOCmin from all the current states of charge SOC; of the N cells CE after complete recharging and a complete relaxation phase of the cellular battery BC (i.e. SOCmin = min(SOCi)).

[0087] For example, in this first embodiment each AHeq; value can be given by the equation: AHeq; = 0.01*(SOC; - SOCmin)*capa;.

[0088] In a second embodiment, in sub-step 20 of step 10-40 one (for example the information estimation device DEI) can determine the initial state of charge SOCini,i of each cell CE as a function of the estimated current state of charge SOC; of the latter (CE) after complete recharging and the complete relaxation phase of the cellular battery BC, of ​​the initial electrical energy storage capacity of the cell CE concerned capa;, and of a target maximum state of charge for an end of charge SOCmaxtible for each cell CE concerned.

[0089] For example, in this second embodiment, in sub-step 20 of step 10-40 one (for example the information estimation device DEI) can estimate for each cell CE its current state of charge SOC; after the complete recharge and the complete relaxation phase of the cellular battery BC. Then, when this estimated current state of charge SOC; is between first si and second s2 chosen thresholds, one (for example the information estimation device DEI) can determine a quantity of ampere-hours dQ; to reach the target maximum state of charge SOCmaxtribable as a function of the estimated current state of charge SOC; of this CE cell, the target maximum state of charge SOCmaxcible and the initial electrical energy storage capacity of the CE cell concerned capa;. It will be understood that each dQ; is representative of an imbalance of the state of charge SOC; of its CE cell (i) compared to the states of charge SOC;- of the Nl other CE cells (i') with i' i.

[0090] For example, the first threshold si may be between 5% and 50%, and the second threshold s2 may be between 55% and 100%. As an illustrative example, the first threshold si may be equal to 30% and the second threshold s2 may be equal to 80%.

[0091] Also for example, the target maximum state of charge SOCmaxcible may be between 90% and 100%. As an illustrative example, the target maximum state of charge SOCmaxcible may be equal to 97%. It should be noted, however, that the target maximum state of charge SOCmaxcible may not be constant. Indeed, it may vary with the aging of the cellular battery BC, for example depending on the SOHC or the kilowatt-hours discharged or the number of charge / discharge cycles of the cellular battery BC.

[0092] Also for example, each quantity of ampere-hour dQ; can be given by the equation: dQ; = (SOCmaxcible - SOCi)*capa; / 100.

[0093] Then, one (for example the information estimation device DEI) can determine the smallest quantity of ampere-hours dQmin to reach the target maximum state of charge SOCmaxtible among all the determined quantities of ampere-hours dQi of the N cells CE, i.e. dQmin = min(dQi).

[0094] Then, one (for example the information estimation device DEI) can determine the initial state of charge SOCini,i of each cell CE as a function of the estimated current state of charge SOC; of the latter (CE), of the smallest quantity of ampere-hours determined dQmin and of the initial electrical energy storage capacity of the cell CE concerned capa;.

[0095] For example, in this first embodiment each initial state of charge SOCini,i can be given by the equation: SOCini,i = SOC; + 100*dQmin / capai.

[0096] It will be noted that in the second embodiment, before using an initial charge state SOCini,i, one (for example the information estimation device DEI) can first check whether it is not saturated and inconsistent. For this purpose, one (for example the information estimation device DEI) can determine a value SOCini,i,coh using an equation of the type: SOCini,i,coh = max {SOCmaxcible -(xl*100*AHeqi / capai, SOCini,i, SOCmaxcible - x2%], where xl and x2 are calibration coefficients used to control the consistency of the imbalance (or deviation) information between cells on the total available energy (or UBE) and to respect dysfunctional margins. In this case, it is the value SOCini,i,coh which is transmitted for each cell CE instead of the initial state of charge SOCini,i.

[0097] It will also be noted that in the presence of a dispersion of SOC; between CE cells exceeding a chosen threshold (for example between 7% and 10%), it is preferable to generate an alert message, preferably a secure one.

[0098] In a third embodiment, in sub-step 20 of step 10-40 one (for example the information estimation device DEI) can determine the initial state of charge SOCini,i of each cell CE as a function of the estimated current state of charge SOC; of the latter (CE) after the complete recharge and the complete relaxation phase of the cellular battery BC, of ​​the initial electrical energy storage capacity of the cell CE concerned capa;, of the target maximum state of charge for an end of charge SOCmaxtrib for each cell CE concerned, and of the smallest state of charge SOCmin among all the current states of charge SOC; of the cells CE after the complete recharge and the complete relaxation phase of the cellular battery BC (i.e. SOCmin = min(SOCi)).

[0099] For example, in this third embodiment two variants can be envisaged according to the value AHeq; of the quantity of ampere-hours to be balanced in the cell CE concerned with respect to the current state of charge SOC; of this cell CE.

[0100] In a first variant, in sub-step 20 of step 10-40 one (for example the information estimation device DEI) can determine the value AHeq; of the quantity of ampere-hours to be balanced in each cell CE as a function of the estimated current state of charge SOCi of this cell CE, of the smallest determined state of charge SOCmin (equal to min(SOCi)), and of the initial electrical energy storage capacity of this cell CE capa;.

[0101] For example, in the third embodiment each AHeq; value can be given by the equation: AHeq; = 0.01*(SOC; - SOCmin)*capa;.

[0102] Then, when the value AHeq; of the quantity of ampere-hours to be balanced corresponds to a state of charge SOC; of a cell CE greater than a third threshold s3 chosen (i.e. SOC; > s3), one (for example the information estimation device DEI) can determine for this cell CE a deviation of state of charge dSOC; as a function of the quantity of ampere-hours to be balanced determined AHeq; and of the initial electrical energy storage capacity capa; of this cell CE.

[0103] For this purpose, one (for example the information estimation device DEI) can, for example, use the equation: dSOC, = KXCAHcq / capa,.

[0104] For example, the third threshold s3 may be between 75% and 85%. As an illustrative example, the third threshold s3 may be equal to 80%.

[0105] Then, one (for example the information estimation device DEI) can determine the largest state of charge deviation dSOCmax among all the determined state of charge deviations dSOC; of the N CE cells, i.e. dSOCmax = max(dSOCi).

[0106] Then, one (for example the information estimation device DEI) can determine the initial state of charge SOCini,i of each cell CE as a function of the target maximum state of charge SOCmaxtargible, of the greatest determined state of charge deviation dSOCmax and of the determined state of charge deviation dSOC; of this cell CE.

[0107] For this purpose, one (for example the information estimation device DEI) can, for example, use the equation: SOCini,i = SOCmaxtarget - (dSOCmax - dSOC;).

[0108] As indicated above, in the third embodiment, the target maximum state of charge SOCmaxcible may be between 90% and 100%. As an illustrative example, the target maximum state of charge SOCmaxcible may be equal to 97%. It will be noted, however, that the target maximum state of charge SOCmaxcible may not be constant. Indeed, it may vary with the aging of the cellular battery BC, for example depending on the SOHC or the kilowatt-hours discharged or the number of charge / discharge cycles of the cellular battery BC.

[0109] In a second variant, in sub-step 20 of step 10-40 one (for example the information estimation device DEI) can determine the value AHeq; of the quantity of ampere-hours to be balanced in each cell CE as a function of the estimated current state of charge SOCi of this cell CE, of the smallest determined state of charge SOCmin (equal to min(SOCi)), and of the initial electrical energy storage capacity of this cell CE capa;.

[0110] For example, in this second variant each AHeq; value can be given by the equation: AHeq; = 0.01*(SOC; - SOCmin)*capa;.

[0111] Then, when the value AHeq; of the quantity of ampere-hours to be balanced corresponds to a state of charge SOC; of a cell CE lower than a fourth threshold s4 chosen (i.e. SOC; < s4), one (for example the information estimation device DEI) can determine for this cell CE a minimum state of charge SOClow; as a function of the quantity of ampere-hours to be balanced determined AHeq; and of the initial electrical energy storage capacity capa; of this cell CE.

[0112] For this purpose, one (for example the information estimation device DEI) can, for example, use the equation: SOClow; = KXEAHcq / capa,, taking as a hypothesis that SOCmin is approximately equal to zero.

[0113] For example, the fourth threshold s4 may be between 15% and 25%. As an illustrative example, the fourth threshold s4 may be equal to 20%.

[0114] Then, one (for example the information estimation device DEI) can determine for each cell CE the quantity of ampere-hours dQ; to reach the target maximum state of charge SOCmaxcible as a function of the determined minimum state of charge SOClow; of this cell CE, of the target maximum state of charge SOCmaxcible and of the initial electrical energy storage capacity capa; of this cell THIS.

[0115] For this purpose, one (for example the information estimation device DEI) can, for example, use the equation: dQ; = (SOCmaxtarget - SOCloWi)*capa; / 100.

[0116] As indicated above, in the second variant, as in the first variant, the target maximum state of charge SOCmaxcible may be between 90% and 100%. As an illustrative example, the target maximum state of charge SOCmaxcible may be equal to 97%. It will be noted, however, that the target maximum state of charge SOCmaxcible may not be constant. Indeed, it may vary with the aging of the cellular battery BC, for example depending on the SOHC or the kilowatt-hours discharged or the number of charge / discharge cycles of the cellular battery BC.

[0117] Then, one (for example the information estimation device DEI) can determine the smallest quantity of ampere-hours dQmin to reach the target maximum state of charge SOCmaxtible among all the quantities of ampere-hours dQ; determined from the N cells CE, i.e. dQmin = min(dQi).

[0118] Then, one (for example the information estimation device DEI) can determine the initial state of charge SOCini,i of each cell CE as a function of the determined minimum state of charge SOClow; of this cell CE, of the smallest quantity of ampere-hours dQmin determined, and of the initial electrical energy storage capacity capa; of this cell CE.

[0119] For this purpose, one (for example the information estimation device DEI) can, for example, use the equation: SOCini,i = SOClow; + 100* dQmin / capa;.

[0120] In the third embodiment, when we have s3 < SOC; < s4, we can decide either to wait for a next cycle (or passage) which respects the threshold (because we are estimating a quantity which deals with aging and therefore we can afford to wait a little), or to accept a degraded mode (with a threshold which does not respect the rules).

[0121] It should also be noted that the first information ibl is supposed to reflect the total useful energy available EtotRef, and therefore must vary mainly with aging which has a slow dynamic of the order of at least one month. Consequently, before updating the value of the first information ibl in the system S, it is preferable:

[0122] - either to only perform the estimation of the first information ibl every M cycles charging / discharging of the BC cell battery to avoid fluctuations (increases),

[0123] - either to verify that the first ibl information has decreased by at least 1% compared to at its last recorded estimate,

[0124] - or even to only carry out the estimation of the first information ibl when a new value of SOHC (capacity loss indicator) or SOHR (resistance increase indicator) is available.

[0125] It will also be noted, as illustrated non-limitingly in [Fig. 3], that step 10-40 may comprise a sub-step 40 in which one (for example the information estimation device DEI) may estimate a second piece of information ib2 which is representative of the state of the certified energy SOCE (or state of health in energy SOHE) of the cellular battery BC, as a function of the first piece of information ibl and of a useful energy at the start of life EtotBoL of the cellular battery BC.

[0126] For example, when the second information ib2 is equal to the state of the SOCE certified energy (or state of health in SOHE energy), it can be determined by means of the following equation: ib2 = 100*EtotRef / EtotBoi = 100*ibl / EtotBoi.

[0127] It will also be noted, as illustrated non-limitingly in [Fig. 2], that the battery calculator CB (or the dedicated calculator of the information estimation device DEI) may also comprise a mass memory MM1, in particular for the temporary storage of the voltage, current and internal temperature measurements of the N cells CE and any intermediate data involved in all its calculations and processing. Furthermore, this battery calculator CB (or the dedicated calculator of the information estimation device DEI) may also comprise an input interface IE for receiving at least the voltage, current and internal temperature measurements of the N cells CE to use them in calculations or processing, possibly after having formatted and / or demodulated and / or amplified them, in a manner known per se, by means of a digital signal processor PR2.In addition, this CB battery calculator (or the dedicated calculator of the DEI information estimation device) can also include an IS output interface, in particular to deliver the first information ibl and the possible second information ib2.

[0128] 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 method for estimating information(s) described above to estimate at least a first piece of information ibl relating to the cellular battery BC of the system S.

Claims

Claims

1. Method for estimating information relating to a cellular battery (BC) of a system (S) comprising N cells (CE) capable of storing electrical energy, with N > 1, and each having a current resistive health state and / or a current capacity health state, said method comprising a step (10-40) in which a final charge state after a discharge is estimated for each cell as a function of said current resistive health state and / or said current capacity health state, characterized in that in said step (10-40) a first piece of information representative of a total energy available in said cellular battery (BC) is also estimated as a function of said estimated final charge states and respective initial charge states of said cells (CE) after a complete recharge.

2. Method according to claim 1, characterized in that in said step (10-40) for each cell (CE) an initial state of charge is used, chosen from a current state of charge estimated just after said complete recharge and a value depending on a quantity of ampere-hours to be balanced in said cell (CE) concerned and a smallest state of charge from all the current states of charge of said cells (CE) after said complete recharge and a phase of complete relaxation of said cellular battery (BC).

3. Method according to claim 1, characterized in that in said step (10-40) said initial state of charge of each cell (CE) is determined as a function of an estimated current state of charge of the latter (CE) after said complete recharge and a complete relaxation phase of said cellular battery (BC), of an initial electrical energy storage capacity of said cell (CE) concerned, and of a target maximum state of charge for an end of charge for each cell (CE) concerned.

4. Method according to claim 3, characterized in that in said step (10-40) for each cell (CE) said current state of charge is estimated after said complete recharge and said complete relaxation phase of said cellular battery (BC), then, when said estimated current state of charge is between first and second chosen thresholds, a quantity of ampere-hours is determined to reach said target maximum state of charge as a function of said estimated current state of charge of this cell (CE), said target maximum state of charge and said initial electrical energy storage capacity of said cell (CE) concerned, then a smallest quantity of ampere-hours is determined to reach said target maximum state of charge among all said quantities of ampere-hours to reach said target maximum state of charge determined for said cells (CE), then said initial state of charge of each cell (CE) is determined as a function of said estimated current state of charge of the latter (CE), of said smallest quantity of ampere-hours to reach said determined target maximum state of charge and of said initial electrical energy storage capacity of said cell (CE) concerned.

5. Method according to claim 3, characterized in that in said step (10-40) said initial state of charge of each cell (CE) is determined as a function further of a smallest state of charge among all the current states of charge of said cells (CE) after said complete recharge and a complete relaxation phase of said cellular battery (BC).

6. Method according to claim 5, characterized in that in said step (10-40) for each cell (CE) a quantity of ampere-hours to be balanced is determined as a function of said estimated current state of charge of this cell (CE), said determined smallest state of charge and said initial electrical energy storage capacity of this cell (CE), then, when said state of charge of a cell (CE) is greater than a third chosen threshold, a state of charge deviation is determined for this cell (CE) as a function of said determined quantity of ampere-hours to be balanced and initial electrical energy storage capacity of said cell (CE) concerned, then a largest state of charge deviation is determined among all said determined state of charge deviations of said cells (CE), then said initial state of charge of each cell (CE) is determined as a function of said target maximum state of charge,of said greatest determined state of charge deviation and said determined state of charge deviation of this cell (CE).,

7. Method according to claim 5, characterized in that in said step (10-40) a quantity of ampere-hours to be balanced is determined for each cell (CE) as a function of said estimated current state of charge of this cell (CE), of said smallest determined state of charge and of said initial electrical energy storage capacity of this cell (CE), then, when said state of charge of a cell (CE) is lower than a fourth chosen threshold, for this cell

8.

9. (CE) a minimum state of charge as a function of said determined quantity of ampere-hours and initial electrical energy storage capacity of said cell (CE) concerned, then determining a quantity of ampere-hours to reach said target maximum state of charge as a function of said determined minimum state of charge of this cell (CE), said target maximum state of charge and said initial electrical energy storage capacity of this cell (CE), then determining a smaller quantity of ampere-hours to reach said target maximum state of charge among all said quantities of ampere-hours to reach said target maximum state of charge determined of said cells (CE), then determining said initial state of charge of each cell (CE) as a function of said determined minimum state of charge of this cell (CE),of said smallest quantity of ampere-hours to reach said determined target maximum state of charge and of said initial electrical energy storage capacity of this cell (CE)., Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the method for estimating information(s) according to one of claims 1 to 7 to estimate at least one item of information relating to a cellular battery (BC) of a system (S) comprising N cells (CE) capable of storing electrical energy, with N > 1, and each having a current resistive health state and / or a current capacity health state. Information estimation device (DEI) for a system (S) comprising a cellular battery (BC) comprising N cells (CE) capable of storing electrical energy, with N > 1, and each having a current resistive health state and / or a current capacity health state, said device (DEI) comprising at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting of estimating for each cell a final state of charge after a discharge as a function of said current resistive health state and / or said current capacity health state, characterized in that said processor (PR1) and memory (MD) are also arranged to carry out the operations consisting of estimating a first piece of information representative of a total energy available in said cellular battery (BC) as a function of said estimated final states of charge and respective initial states of charge of said cells (CE) after a complete recharge.

10. System (S) comprising a cellular battery (BC) comprising N cells (CE) capable of storing electrical energy, with N > 1, and each having a current resistive health state and / or a current capacity health state, characterized in that it further comprises an information estimation device (DEI) according to claim 9.

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