CELLULAR BATTERY RECHARGE MANAGEMENT IN A SYSTEM BASED ON CELL CHEMISTRY

Abstract

A method is used to manage the charging of a cellular battery comprising electrochemical cells, each with an estimated cell state of charge, a measured cell temperature, and a measured cell voltage, and equipping a system. This method includes a step (10-70) in which, when the cellular battery is requested to be recharged, at least one maximum charging current is determined as a function of either the measured cell temperatures and measured cell voltages when the electrochemical cells have an open-circuit voltage versus state of charge curve without a plateau region, or the measured cell temperatures and estimated cell states of charge when the electrochemical cells have an open-circuit voltage versus state of charge curve with at least one plateau region. Figure 3

Description

Title of the invention: MANAGEMENT OF THE RECHARGES OF A CELLULAR BATTERY OF A SYSTEM BASED ON CELL CHEMISTRY Technical field of the invention

[0001] The invention relates to cellular batteries, and more specifically to the management of recharging of such cellular batteries. State of the art

[0002] In many fields, such as vehicles (possibly automotive), cellular batteries are used in which the cells are electrochemical and can have different chemistries.

[0003] During a recharging phase of a cellular battery, the computer associated with the latter is responsible for controlling the recharging so that it is done without risk and with the most stable recharging current possible, so as to guarantee the performance of this cellular battery for a predefined duration. In fact, currently, the battery computer determines successive maximum recharging currents which are a function of the measured cellular temperatures and the measured cellular voltages, and decides to terminate a recharge when the total state of charge (or SOC ("State Of Charge")) of the cellular battery is equal to the total state of charge desired by the user of the system, knowing that the desired total state of charge is considered to have been reached when a corresponding maximum cellular voltage is reached.

[0004] However, as is known to those skilled in the art, the cellular batteries presented above have a curve of evolution of their no-load voltage as a function of their total state of charge not having a plateau zone or having at least one plateau zone (at least from approximately 5%). Here, the term "plateau zone" is understood to mean a zone in which a small variation in the cellular no-load voltage (typically less than 10 mV) corresponds to a large variation in the cellular state of charge (typically greater than 15%).Thus, cellular batteries with electrochemical cells of the Lithium Iron Phosphate (or LFP) type have a curve of evolution of their no-load voltage as a function of their state of charge which presents at least one plateau zone (and therefore which increases very slowly), whereas cellular batteries with electrochemical cells of the so-called "mixed metal oxide" type (for example NCM (Nickel Cobalt Manganese) or NCA (Nickel Cobalt Aluminum)) have a curve of evolution of their no-load voltage as a function of their state of charge which does not present a plateau zone (and therefore which increases rapidly).

[0005] Due to these variations in the evolution of the total open-circuit voltage as a function of the total state of charge according to the chemistry of the electrochemical cells, the control of recharges proves to be insufficiently adapted to cellular batteries with electrochemical cells having a curve of evolution of their no-load voltage according to their state of charge which presents at least one plateau zone. It will be understood in fact, that it proves to be particularly difficult to know if a maximum cell voltage sought actually corresponds to the desired total state of charge when the total state of charge can vary greatly without this being observable on the evolution of the maximum cell voltage, and therefore during a complete recharge it frequently happens that the user is made to wait longer than necessary (when it is difficult to know if the maximum state of charge has been reached).

[0006] Furthermore, the problem described above is increased by the fact that the state of charge is a parameter which is estimated, and therefore it may be subject to deviations from reality which may result in a final undercharge which is penalizing in terms of autonomy or a final overload which is potentially dangerous because it may cause internal damage and / or heating which may trigger a fire in the event of thermal runaway.

[0007] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0008] It proposes in particular for this purpose a management method intended to allow the management of recharging of a cellular battery comprising electrochemical cells each having an estimated cellular charge state, a measured cellular temperature and a measured cellular voltage, and suitable for equipping a system.

[0009] This management method is characterized by the fact that it comprises a step in which, in the event of a request to recharge the cellular battery, at least one maximum recharge current is determined as a function either of the measured cellular temperatures and measured cellular voltages when the electrochemical cells have a curve of evolution of an open-circuit voltage as a function of their state of charge not having a plateau zone, or of the measured cellular temperatures and estimated cellular states of charge when the electrochemical cells have a curve of evolution of an open-circuit voltage as a function of their state of charge having at least one plateau zone.

[0010] Thanks to this management of recharges as a function of the chemistry of the electrochemical cells, it is possible to reduce the duration of complete recharges when the electrochemical cells have a curve of evolution of their no-load voltage as a function of their state of charge which presents at least one plateau zone, while reducing the risk of occurrence of an overcharge of the cellular battery.

[0011] The management method according to the invention may include other characteristics which may be taken separately or in combination, and in particular:

[0012] - in its step, in the presence of electrochemical cells having a curve of evolution of an open-circuit voltage as a function of their state of charge not presenting a plateau zone, we can determine each maximum recharge current as a function of the smallest and largest cell temperatures measured among all the cell temperatures measured and of a largest cell voltage measured among all the cell voltages measured;

[0013] - in the presence of the first option, in its step, one can determine in a first correspondence table, establishing a correspondence between charging current values ​​and pairs of cell temperature and cell voltage, on the one hand, a first charging current value corresponding to the smallest measured cell temperature and highest measured cell voltage, and, on the other hand, a second charging current value corresponding to the largest measured cell temperature and highest measured cell voltage. Then, the maximum charging current can be determined by taking the smallest of these first and second determined charging current values;

[0014] - in its step, in the presence of electrochemical cells having a curve of evolution of their no-load voltage as a function of their state of charge which has at least one plateau zone, we can determine each maximum recharge current as a function of the smallest and largest cell temperatures measured among all the measured cell temperatures and of a largest estimated cell state of charge among all the estimated cell states of charge;

[0015] - in the presence of the last option, in its step, one can determine in a second correspondence table, establishing a correspondence between recharge current values ​​and pairs of cell temperature and cell state of charge, on the one hand, a third recharge current value corresponding to the smallest measured cell temperature and the largest estimated cell state of charge, and, on the other hand, a fourth recharge current value corresponding to the largest measured cell temperature and the largest estimated cell state of charge. Then, the maximum recharge current can be determined by taking the smallest of these third and fourth determined recharge current values;

[0016] - in its step, the current recharge can be terminated when a voltage at terminals of the cellular battery is equal to a voltage value which is chosen according to a desired total state of charge, and that the maximum recharge current has become lower than a limit value of controllability of the recharge;

[0017] - in the presence of the last option, in its step, when a recharge request partial is requested, a corrected total state of charge can be used which is determined from an estimated total state of charge of the cell battery and a margin total state of charge inaccuracy.

[0018] The invention also provides a computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing a management method of the type presented above for managing recharges of a cellular battery comprising electrochemical cells each having an estimated cellular charge state, a measured cellular temperature and a measured cellular voltage, and capable of equipping a system.

[0019] The invention also proposes a management device intended to manage recharges of a cellular battery comprising electrochemical cells each having an estimated cellular charge state, a measured cellular temperature and a measured cellular voltage, and suitable for equipping a system.

[0020] This management 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, in the event of a request to recharge the cellular battery, in determining at least one maximum recharge current as a function either of the measured cellular temperatures and measured cellular voltages when the electrochemical cells have a curve of evolution of an open-circuit voltage as a function of their state of charge not having a plateau zone, or of the measured cellular temperatures and estimated cellular states of charge when the electrochemical cells have a curve of evolution of an open-circuit voltage as a function of their state of charge having at least one plateau zone.

[0021] The invention also proposes a system comprising, on the one hand, a cellular battery comprising electrochemical cells each having an estimated cellular charge state, a measured cellular temperature and a measured cellular voltage, and, on the other hand, a management device of the type presented above. Brief description of the figures

[0022] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0023] [Fig-1] schematically and functionally illustrates an example of the embodiment of a vehicle comprising a management device according to the invention and a GMP with an electric motor powered by a cellular battery associated with a battery computer,

[0024] [Fig.2] schematically and functionally illustrates an example of the embodiment of a battery calculator comprising a management device according to the invention, and

[0025] [Fig.3] schematically illustrates an example of an algorithm implementing a management method according to the invention. Detailed description of the invention

[0026] The invention aims in particular to propose a management method, and a device associated DG management, intended to enable the management in a system S of the recharges of a BC cellular battery according to the chemistry of the electrochemical cells CE of the latter (BC).

[0027] 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. 1]. But the invention is not limited to this type of system. It relates in fact to any type of system comprising at least one cellular battery (rechargeable for example by an external power source temporarily coupled to this system). 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.

[0028] 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).

[0029] [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, a converter CV, and a management device DG according to the invention.

[0030] 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 may 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.

[0031] 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.

[0032] The main electrical circuit (or "high voltage" or "power") is connected, on the one hand, to the cellular battery BC via an interface device, and, on the other hand, to electronic equipment, such as for example the CV converter and the MME motor machine. It also allows the recharging of the cellular battery BC by a external power source SA temporarily coupled to the vehicle S, for example via a charging cable CR temporarily connected to a charging connector CN of the vehicle S.

[0033] 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 torque to move the system S (here a vehicle), as well as possibly to recover regenerative braking torque. The operation of the GMP is supervised by a supervision computer CS.

[0034] 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 regenerative braking 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.

[0035] 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.

[0036] The operation of the driving machine MME is controlled by a machine computer CM, and supervised by the supervision computer CS.

[0037] 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.

[0038] 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.

[0039] The cellular battery BC comprises at least one electrochemical cell CE, and preferably several, having a curve of evolution of its no-load voltage uvc as a function of its state of charge ecc having at least one plateau zone or having no plateau zone.

[0040] It is recalled that here the term “plateau zone” means an area in which a low variation in the cellular open-circuit voltage UVC (typically less than 10 mV) corresponds to a high variation in the cellular state of charge ECC (typically greater than 15%).

[0041] For example, each electrochemical cell CE may be of the lithium-ion (or Li-ion) type. Also for example, the cell battery BC may be of the low voltage type (typically 450 V for illustration). But it could be of the medium voltage or high voltage type.

[0042] It will be noted, as illustrated non-limitingly in [Fig. 1], that when the cellular battery BC comprises several electrochemical cells CE, they can be part of modules MC which are coupled together, for example in series. Here, the term “module MC” means a group of at least one electrochemical cell CE. When an MC module comprises several electrochemical cells CE, the latter (CE) can be coupled together in series and / or in parallel.

[0043] It will be noted that the cellular battery BC is associated with a battery box BB which notably comprises means for measuring total voltage ut, cell voltage uc, current and cell temperature te (not illustrated), and a battery calculator CB. This battery calculator CB centralizes the current measurements, the voltage measurements and the cell temperature measurements (notably those which individually concern each of the N electrochemical cells CE), and estimates parameters of the cellular battery BC as a function of these measurements, and notably its internal resistance, its minimum voltage, its charge, its total state of charge (or SOC) ect and its maximum state of charge ecm, the cell state of charge ecc (of each electrochemical cell CE). It is recalled that the maximum state of charge ecm varies over time, and notably as a function of the aging of the cellular battery BC and the temperature of the air surrounding the latter (BC).

[0044] It will also 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).

[0045] As mentioned above, the invention proposes in particular a management method intended to allow the management in the system S (here a vehicle) of the recharges of its cellular battery BC as a function of the chemistry of the electrochemical cells CE of the latter (BC).

[0046] This (management) method can be implemented at least partially by the DG management device (illustrated in [Fig.2]) which comprises for this purpose at least one PR1 processor, for example a digital signal processor (or DSP ("Digital Signal Processor")), and at least one MD memory. This DG management device 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.

[0047] The memory MD is live in order to store instructions for the implementation by the processor PR1 of at least part of the management 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.

[0048] In the example illustrated non-limitingly in Figures 1 and 2, the management device DG is part of the battery calculator CB. But it could be part of another calculator embedded in the system S (such as for example the calculator CA of the internal charger CH), or could comprise its own dedicated calculator.

[0049] As illustrated non-limitingly in [Fig.2], the (management) method, according to the invention, comprises a step 10-70 which is implemented each time a user of the system S wants to recharge the cellular battery BC (and therefore, here, once the recharging connector CN has been temporarily coupled to a power source SA external to the vehicle S, via a recharging cable CR).

[0050] Step 10-70 of the method comprises a sub-step 10 in which one (for example the management device DG) receives from the user of the system S a request to recharge the cellular battery BC which defines a desired state of charge ecd.

[0051] Step 10-70 of the method also comprises a sub-step 40 or 60 in which one (for example the management device DG) determines at least one maximum recharge current irmax which is a function of:

[0052] - either measured cell temperatures te and measured cell voltages uc when the electrochemical cells CE have a curve of evolution of their open-circuit voltage uvc as a function of their state of charge ecc not presenting a plateau zone,

[0053] - either measured cell temperatures te and cell states of charge estimated ecc when the electrochemical cells CE have a curve of evolution of their no-load voltage uvc as a function of their state of charge ecc presenting at least one plateau zone.

[0054] It is also recalled that once a maximum recharge current irmax has been determined (as a function of the chemistry of the electrochemical cells CE), one (for example the management device DG) imposes the use by the power source SA of a recharge current ir which is less than or equal to this maximum recharge current. irmax.

[0055] It will also be noted that several maximum recharge currents irmax can be successively determined so that the total state of charge ect can become equal to the desired state of charge ecd.

[0056] Thanks to these considerations of the estimated cellular states of charge ecc or the measured cellular voltages uc depending on whether the electrochemical cells CE have a curve of evolution of their no-load voltage uvc as a function of their state of charge ecc which has at least one plateau zone or does not have a plateau zone, it is now possible to precisely control all the recharges whatever the chemistry of the electrochemical cells CE. Consequently, the invention makes it possible to reduce the duration of complete recharges when the electrochemical cells CE have a curve of evolution of their no-load voltage uvc as a function of their state of charge ecc which has at least one plateau zone, while reducing the risk of occurrence of an overcharge of the cellular battery BC.

[0057] It will be noted that when the CE electrochemical cells are of Lithium-ion technology and they have a curve of evolution of their no-load voltage uvc as a function of their state of charge ecc which has at least one plateau zone, they can be of the Lithium Iron Phosphate (or LFP) type, for example. It will also be noted that when the CE electrochemical cells are of Lithium-ion technology and they have a curve of evolution of their no-load voltage uvc as a function of their state of charge ecc not having a plateau zone, they can, for example, be of the mixed metal oxide type (for example NCM (Nickel Cobalt Manganese) or NCA (Nickel Cobalt Aluminum)). But the invention is not limited to CE electrochemical cells of Lithium-ion technology.

[0058] For example, and as illustrated non-limitingly in [Fig. 3], step 10-70 of the method may comprise a sub-step 20 in which one (for example the management device DG) can determine the chemistry of the electrochemical cells CE, and more precisely whether the latter (CE) have a curve of evolution of their open-circuit voltage uvc as a function of their state of charge ecc which has at least one plateau zone or does not have a plateau zone. In this case, if the electrochemical cells CE have a curve of evolution of their open-circuit voltage uvc as a function of their state of charge ecc which does not have a plateau zone, step 10-70 of the method may comprise at least sub-step 40 described later. On the other hand, if the electrochemical cells CE have a curve of evolution of their no-load voltage uvc as a function of their state of charge ecc which presents at least one plateau zone, step 10-70 of the method can comprise at least sub-step 60 described later.

[0059] Also for example, when we are in the presence of electrochemical cells CE having a curve of evolution of their no-load voltage uvc as a function of their state of ecc charge not having a plateau zone, step 10-70 can, as illustrated non-limitingly in [Fig. 3], comprise sub-step 40 in which one (for example the management device DG) can determine each maximum recharge current irmax as a function of the smallest tcmin and largest tcmax measured cell temperatures among all the measured cell temperatures te and the largest measured cell voltage ucmax among all the measured cell voltages uc.

[0060] In this case, step 10-70 can, as illustrated non-limitingly in [Fig. 3], comprise a sub-step 30 in which one (for example the management device DG) can begin by determining in a first correspondence table, establishing a correspondence between recharge current values ​​ir and pairs of cell temperature te and cell voltage uc, first vl and second v2 recharge current values.The first charging current value vl corresponds to the pair with the smallest measured cell temperature tcmin and the largest measured cell voltage ucmax in the first lookup table. The second charging current value v2 corresponds to the pair with the largest measured cell temperature tcmax and the largest measured cell voltage ucmax in the first lookup table. Then, in substep 40 of step 10-70, one (for example the management device DG) can determine the maximum charging current irmax by taking the smallest of the first vl and second v2 determined charging current values ​​(i.e. irmax = min(vl; v2)).

[0061] When there are electrochemical cells CE having a curve of evolution of their no-load voltage uvc as a function of their state of charge ecc which has at least one plateau zone, in sub-step 60 of step 10-70, one (for example the management device DG) can determine each maximum recharge current irmax as a function of the smallest tcmin and largest tcmax measured cell temperatures among all the measured cell temperatures te and the largest estimated cell state of charge eccmax among all the estimated cell states of charge ecc.

[0062] In this case, step 10-70 may, as illustrated non-limitingly in [Fig. 3], comprise a sub-step 50 in which one (for example the management device DG) may begin by determining in a second correspondence table, establishing a correspondence between recharge current values ​​ir and pairs of cell temperature te and cell state of charge ecc, third v3 and fourth v4 recharge current values. The third recharge current value v3 corresponds to the pair comprising the smallest measured cell temperature tcmin and the largest estimated cell state of charge eccmax in the second correspondence table. The fourth recharge current value v4 corresponds to the pair comprising the highest measured cell temperature tcmax and the highest estimated cell state of charge eccmax in the second lookup table. Then, in substep 60 of step 10-70, one (for example the management device DG) can determine the maximum recharge current irmax by taking the smallest of the third v3 and fourth v4 determined recharge current values ​​(i.e. irmax = min(v3; v4)).

[0063] It will be noted that, whatever the chemistry of the electrochemical cells CE, step 10-70 may, as illustrated non-limitingly in [Fig. 3], comprise a sub-step 70 in which it is possible to terminate (for example the management device DG may trigger the stopping of) the recharging when the total voltage ut at the terminals of the cellular battery BC is equal to a voltage value vt which is chosen as a function of the desired total state of charge ecd, and the maximum recharging current irmax has become lower than a limit value for controllability of the recharging.

[0064] In this case, in sub-step 70 of step 10-70, when a partial recharge request is requested by the user, one (for example the management device DG) can use a corrected total state of charge ectc which is determined from the estimated total state of charge ect and a total state of charge inaccuracy margin mie. Preferably, the corrected total state of charge ectc is equal to the estimated total state of charge ect minus the total state of charge inaccuracy margin mie (i.e. ectc = ect - mie).

[0065] For example, the total state of charge inaccuracy margin mie may be between 1% and 5% of the estimated total state of charge ect. As an illustrative example, the total state of charge inaccuracy margin mie may be equal to 3% of the estimated total state of charge ect. But other values ​​of chosen duration may be used. For example, the value of the total state of charge inaccuracy margin mie may be chosen during the development phase of the cellular battery BC.

[0066] This option is intended to prevent the actual total state of charge from being greater than the estimated total state of charge, etc., because this could lead to the determination of a maximum recharge current irmax greater than what the cellular battery BC is capable of supporting at the time in question. It will be understood that in such a situation there could be a potentially dangerous final overcharge because it could lead to internal damage and / or heating that could trigger a fire in the event of thermal runaway. This therefore increases the safety of the system S and its users and the lifespan of the cellular battery BC.

[0067] It will also be noted that if the recharge request received in sub-step 10 indicates that the user wants to obtain a desired total state of charge ecd equal to the maximum state of charge ecm that the cellular battery BC can support at the instant in question, it is possible, for example, to impose (for example the management device DG can, for example, trigger the imposition of) the use of the maximum recharge current irmax up to obtaining a maximum cellular voltage ucmax greater than or equal to a first threshold if.

[0068] It will also be noted that the first threshold si may depend on the chemistry and aging of the cell battery BC, as well as possibly on the temperature of the air surrounding the latter (BC). In this case, the first threshold si is determined by the management device DG according to the variable parameters of the cell battery BC. But it could also be predefined according to the chemistry of the cell battery BC.

[0069] Then, once we have ucmax > si, we can perform a (for example the management device DG can trigger the performance of a) multiple step charge (or "multiple steps charge"). Here, "multiple step charge" means a charging phase comprising a multiplicity of successive replacement steps prn. In each step prn, we can impose (for example the management device DG can trigger the imposition of) the use by the power source SA of a charging current irn which is strictly lower than the previous charging current irn (used during the previous step prn i), until the charging current irn used during the current step prn (with n' > n) is lower than a second threshold s2.

[0070] At least two different embodiments of the multi-step recharging phase can be envisaged.

[0071] For example, in a first embodiment, when the recharge current used irn is greater than the second threshold s2, it is possible to interrupt (for example the management device DG can trigger an interruption of) the multi-step recharge when the number vp of steps prn performed is equal to a maximum number of steps npmax. It will be understood that this interruption is decided even though the last recharge current irn used is still greater than the second threshold s2, because it is considered that performing at least one additional step prn+i would not make it possible to significantly increase the current state of charge of the cellular battery BC.

[0072] Also for example, the maximum number of steps npmax can be between 8 and 12. As an illustrative example, the maximum number of steps npmax can be equal to 10. But other values ​​of the maximum number of steps npmax can be used. For example, the value of the maximum number of steps npmax can be chosen during the development phase of the cell battery BC.

[0073] Alternatively, in a second embodiment, when the recharge current used irn is greater than the second threshold s2, it is possible to interrupt (for example the management device DG can trigger an interruption of) the multi-step recharge when the latter has been carried out for a duration which is equal to a chosen duration of. It will be understood that this interruption is decided even though the last recharge current irn used is still greater than the second threshold s2, because it is considered that continuing the multi-step charging phase would not significantly increase the current state of charge of the BC cellular battery.

[0074] For example, the chosen duration of can be between 1 hour and 12 hours. As an illustrative example, the chosen duration of can be equal to 5 hours. But other values ​​of chosen duration of can be used. For example, the value of the chosen duration of can be chosen during the development phase of the cellular battery BC. It will be noted that this chosen duration of can possibly be variable depending on the type of the power source SA used (fast charging or slow charging).

[0075] It will also be noted that the second threshold s2 may be a function of the minimum recharge current that can be delivered by the power source SA ensuring the recharge. As an illustrative example, the second threshold s2 may be equal to the minimum recharge current. It will be understood that it is pointless to continue a multi-step recharge phase by imposing the use of a new recharge current ir„ lower than the minimum recharge current (or limit value for controllability of the recharge) that can be delivered by the power source SA because this would not make it possible to increase the current state of charge of the cellular battery BC. But other values ​​of the second threshold s2 may be used, and in particular a value slightly higher than the minimum recharge current. For example, the value of the second threshold s2 may be chosen during the development phase of the cellular battery BC.

[0076] It will also be noted that in step 10-70, during each step prn of the multi-step recharge it is possible to impose (for example the management device DG can trigger the imposition of) the use of a recharge current irn which is equal to the previous recharge current irn i multiplied by a chosen coefficient cc which is strictly less than one (i.e. irn = irn4*cc, with cc < 1).

[0077] For example, in step 10-70 the chosen coefficient cc may be between 0.6 and 0.95. As an illustrative example, the chosen coefficient cc may be equal to 0.85. But other values ​​of the chosen coefficient cc may be used. For example, the value of the chosen coefficient cc may be chosen during the development phase of the cellular battery BC.

[0078] It will also be noted, as illustrated non-limitingly in [Fig.l], that the battery calculator CB (or the calculator of the management device DG) can also comprise a mass memory MM1, in particular for storing the total voltage ut, each cell voltage uc, each cell temperature te, the total state of charge ect, each cell state of charge ecc, the maximum state of charge ecm, the desired state of charge ecd, the possible minimum recharge current that can be delivered by the power source SA, the possible aging state of the cell battery BC, as well as possible intermediate data involved in all its calculations and processing. Furthermore, this battery calculator CB (or the calculator of the device management device DG) may also comprise an input interface IE for receiving at least the total voltage ut, each cell voltage uc, each cell temperature te, the total state of charge ect, each cell state of charge ecc, the maximum state of charge ecm, the desired state of charge ecd, the possible minimum recharge current that can be delivered by the power source SA, the possible aging state of the cell battery BC, to use them in calculations or processing, possibly after having shaped and / or demodulated and / or amplified them, 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 management device DG) may also comprise an output interface IS, in particular for delivering each message (or order) containing the definition of the imposed recharge current, and each message (or order) to stop the recharge.

[0079] 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 management method described above to manage the recharging of the cellular battery BC equipping the system S.

Claims

Claims

1. Method for managing recharges of a cellular battery (BC) comprising electrochemical cells (CE) each having an estimated cellular state of charge, a measured cellular temperature and a measured cellular voltage, and suitable for equipping a system (S), characterized in that it comprises a step (10-70) in which, in the event of a request to recharge said cellular battery (BC), at least one maximum recharge current is determined as a function either of said measured cellular temperatures and measured cellular voltages when said electrochemical cells (CE) have a curve of evolution of an open-circuit voltage as a function of their state of charge not having a plateau zone, or of said measured cellular temperatures and said estimated cellular states of charge when said electrochemical cells (CE) have a curve of evolution of an open-circuit voltage as a function of their state of charge having at least one plateau zone.

2. Method according to claim 1, characterized in that in said step (10-70), in the presence of electrochemical cells (CE) having a curve of evolution of their no-load voltage as a function of their state of charge not having a plateau zone, each maximum recharge current is determined as a function of the smallest and largest cell temperatures measured among all said measured cell temperatures and of a largest cell voltage measured among all said measured cell voltages.

3. Method according to claim 2, characterized in that in said step (10-70) there is determined in a first correspondence table, establishing a correspondence between recharge current values ​​and pairs of cell temperature and cell voltage, i) a first recharge current value corresponding to said smallest measured cell temperature and largest measured cell voltage, and ii) a second recharge current value corresponding to said largest measured cell temperature and largest measured cell voltage, then said maximum recharge current is determined by taking the smallest of said first and second determined recharge current values.

4. Method according to claim 1, characterized in that in said step (10-70), in the presence of electrochemical cells (CE) having a curve of evolution of their open-circuit voltage as a function of their state of charge having at least one plateau zone, each maximum recharge current is determined based on the smallest and largest measured cell temperatures among all said measured cell temperatures and a largest estimated cell state of charge among all said estimated cell states of charge.

5. Method according to claim 4, characterized in that in said step (10-70) there is determined in a second correspondence table, establishing a correspondence between recharge current values ​​and pairs of cell temperature and cell state of charge, i) a third recharge current value corresponding to said smallest measured cell temperature and said largest estimated cell state of charge, and ii) a fourth recharge current value corresponding to said largest measured cell temperature and said largest estimated cell state of charge, then said maximum recharge current is determined by taking the smallest of said third and fourth determined recharge current values.

6. Method according to one of claims 1 to 5, characterized in that in said step (10-70) said recharging is terminated when a voltage at the terminals of said cellular battery (BC) is equal to a voltage value chosen as a function of a desired total state of charge, and said maximum recharging current has become lower than a limit value for controllability of the recharging.

7. Method according to claim 6, characterized in that in said step (10-70), when a partial recharge request is requested, a corrected total state of charge determined from an estimated total state of charge of said cellular battery (BC) and a total state of charge inaccuracy margin is used.

8. Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the management method according to one of claims 1 to 7 for managing recharges of a cellular battery (BC) comprising electrochemical cells (CE) each having an estimated cellular charge state, a measured cellular temperature and a measured cellular voltage, and capable of equipping a system (S).

9. Management device (DG) for managing recharges of a cellular battery (BC) comprising electrochemical cells (CE) each having an estimated cellular charge state, a measured cellular temperature and a measured cellular voltage, and suitable for equipping a system (S), characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting, in the event of a request to recharge said cellular battery (BC), in determining at least one maximum recharge current as a function either of said measured cellular temperatures and measured cellular voltages when said electrochemical cells (CE) have a curve of evolution of an open-circuit voltage as a function of their state of charge not having a plateau zone, or of said measured cellular temperatures and said estimated cellular states of charge when said electrochemical cells (CE) have a curve of evolution of an open-circuit voltage as a function of their state of charge having at least one plateau zone.

10. System (S) comprising a cellular battery (BC) comprising electrochemical cells (CE) each having an estimated cellular charge state, a measured cellular temperature and a measured cellular voltage, characterized in that it further comprises a management device (DG) according to claim 9.

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