FR3139913A1 - ACCURATE ESTIMATION OF THE MAXIMUM OPERATING POWER OF A VEHICLE CELL BATTERY - Google Patents

Abstract

An estimation method is implemented in a vehicle comprising a cellular battery comprising N cells each having a cellular voltage, with N ≥ 2. This estimation method comprises a step (10-30) in which the maximum power is estimated of operation of the cellular battery by multiplying an estimated primary maximum power by a limitation coefficient estimated by means of a chosen function and having a parameter independent of an internal temperature in the cellular battery and defined by a ratio between a first difference, between an extreme cellular voltage of the cells and a usage limit voltage, and a second difference, between a limiting start-up voltage and this usage limit voltage. Figure 3

Description

ACCURATE ESTIMATION OF THE MAXIMUM OPERATING POWER OF A VEHICLE CELLULAR BATTERY Technical field of the invention

The invention relates to vehicles comprising a rechargeable cellular battery, and more specifically to the estimation of the maximum operating power of such a cellular battery.

State of the art

Some vehicles, possibly of the automobile type, include a rechargeable cellular battery, generally called "main" (or traction) because it is responsible for electrically supplying a main electrical circuit (sometimes called "high voltage") to which at least one electric motor of their powertrain (or GMP) is connected.

In some of the aforementioned vehicles, a maximum operating electrical power of the cellular battery is estimated to prevent it from being subject to undervoltage, overvoltage or excessive temperature. In other words, in each discharge phase of the cellular (main) battery a battery calculator (associated with the latter) estimates the maximum electrical power that the cellular battery is allowed to supply to the main electrical circuit, and in each recharge phase (or "regeneration") of the cellular (main) battery this battery calculator estimates the maximum electrical power that the cellular battery is allowed to receive from the main electrical circuit.

This maximum operating electrical power is generally a primary (or gross) maximum power which is simply estimated based on the internal temperature of the cellular battery and the state of charge (or “state of charge”) of the latter. In this case, the battery calculator generally includes a correspondence table (or mapping) establishing a correspondence between internal temperature and state of charge pairs and primary maximum powers.

In order to try to prevent cell voltages from falling below a cut-off voltage, it has been proposed to limit the estimated maximum primary power by multiplying it by a limiting coefficient whose value varies between zero and one. This limitation technique is called "derating" in English.

There are several known limiting techniques.

A first limitation technique consists in managing the adaptation of the primary maximum power by means of a time delay. A disadvantage of this first limitation technique lies in the fact that the duration of the time delay cannot be calibrated in order to correspond to all possible cases of stress on the cellular battery (polarization profile, internal temperature, aging, etc.).

A second limitation technique is to use many look-up tables (or maps) corresponding to different internal temperatures, so as to take into account the actual internal temperature at the time considered. A disadvantage of this second limitation technique is that it requires a very large memory to store all the look-up tables (or maps), which is considered too expensive for a production vehicle.

A third limitation technique, notably described in patent document KR-A-20200066476, consists of performing an open-loop limitation by imposing a reduction of xkW/second to the primary maximum power. A disadvantage of this third limitation technique lies in the fact that it does not take into account the limit voltage of use (or cut-off voltage), which moreover varies according to the internal temperature. Consequently, it is not precise, and therefore cannot protect against the risks of undervoltage and overvoltage which lead to untimely openings of contactors (or switches) of the isolation device which is associated with the cellular battery and responsible for isolating it from the main electrical circuit (or high voltage).

There is therefore a real need to make the estimation of the limitation coefficient more precise and more reliable, particularly when the power available in the cellular battery is significant. Indeed, in this case the GMP believes that it can use all this power, but when the extreme (minimum) cellular voltage drops very quickly during discharge, it will collapse after passing below the limit voltage of use. Similarly, during discharge, when the extreme (maximum) cellular voltage increases very quickly, it will increase even faster after passing above the limit voltage of use. The older the cellular battery, the more this phenomenon is increased because the more we overestimate the power actually available.

The invention is therefore intended in particular to improve the situation.

Presentation of the invention

It proposes in particular for this purpose an estimation method, on the one hand, intended to be implemented in a vehicle comprising a cellular battery comprising N cells each having a cellular voltage, with N ≥ 2, and, on the other hand, comprising a step in which a maximum operating power of the cellular battery is estimated by multiplying an estimated primary maximum power by an estimated limitation coefficient.

This estimation method is characterized by the fact that in its step the limitation coefficient is estimated by means of a chosen function having a parameter independent of an internal temperature in the cellular battery and defined by a ratio between a first difference, between an extreme cellular voltage of the cells and a limit usage voltage, and a second difference, between a limiting start voltage and the limit usage voltage.

Thanks to the invention, we now have a limitation coefficient which is generically calibrated and optimized according to the internal temperature, which avoids having to use a very large memory to store a multitude of correspondence tables (or maps) for a multitude of different internal temperatures, and allows protection against the risks of undervoltage and overvoltage.

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

- in its step, the extreme cell voltage can be either a minimum cell voltage when the cell battery is in a discharge phase, or a maximum cell voltage when the cell battery is in a recharge phase;

- in its step, we can choose a linear function when the second difference is less than or equal to a chosen threshold;

- in its step, we can choose a non-linear function when the second difference is greater than a chosen threshold;

- in its step, the maximum operating power can be maintained at a constant value either when in a discharge phase of the cellular battery the extreme cellular voltage begins to increase again after a decrease phase and remains lower than a chosen recovery voltage, or when in a recharge phase of the cellular battery the extreme cellular voltage begins to decrease again after a increase phase and remains higher than the chosen recovery voltage;

- in its step, we can estimate a limitation coefficient which imposes either a first constant decrease in the maximum operating power as long as the extreme cell voltage is lower than the limit voltage of use, or a second decrease strictly greater than the first decrease and increasing when a third difference decreases between the extreme cell voltage and a prohibited limit voltage;

- in the presence of the last option, in its step, the second decrease can vary non-linearly when the third difference decreases.

The invention also provides a computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing an estimation method of the type presented above, in a vehicle comprising a cellular battery comprising N cells each having a cellular voltage, with N ≥ 2, to estimate a maximum operating power for this cellular battery.

The invention also proposes an estimation device, on the one hand, intended to equip a vehicle comprising a cellular battery comprising N cells each having a cellular voltage, with N ≥ 2, and, on the other hand, comprising at least one processor and at least one memory arranged to carry out the operations consisting in estimating a maximum operating power of the cellular battery by multiplying an estimated primary maximum power by an estimated limitation coefficient.

This estimation device is characterized by the fact that its processor and memory are also arranged to carry out the operations consisting of estimating the limitation coefficient by means of a chosen function and having a parameter independent of an internal temperature in the cellular battery and defined by a ratio between a first difference, between an extreme cellular voltage of the cells and a limit usage voltage, and a second difference, between a limitation start voltage and this limit usage voltage.

The invention also proposes a vehicle, possibly of the automobile type, and comprising, on the one hand, a cellular battery comprising N cells each having a cellular voltage, with N ≥ 2, and, on the other hand, an estimation device of the type presented above.

Brief description of the figures

Other characteristics and advantages of the invention will appear on examining the detailed description below, and the attached drawings, in which:

schematically and functionally illustrates an exemplary embodiment of a vehicle comprising a powertrain, with an electric motor connected to a main electrical circuit to which a cellular battery is connected, and an estimation device according to the invention,

schematically and functionally illustrates an exemplary embodiment of a battery calculator comprising an exemplary embodiment of an estimation device according to the invention,

schematically illustrates an example of an algorithm implementing an estimation method according to the invention,

schematically illustrates in a diagram two examples of curves of evolution of limitation coefficients respectively linear (c1) and non-linear (c2) as a function of the parameter equal to the ratio between the first and second differences, and to the left of the diagram the respective positions of particular voltages involved in the invention,

schematically illustrates within a first diagram (upper) an example of a time evolution curve of the extreme cell voltage in a discharge phase, and within a second diagram (lower) two examples of time evolution curves of the maximum operating power respectively in the absence (c3) and in the presence (c4) of the limitation coefficient, in the discharge phase corresponding to the first diagram, and

schematically illustrates in a diagram an example of a curve showing the evolution of the maximum operating power as a function of the extreme cell voltage, in a discharge phase.

Detailed description of the invention

The invention aims in particular to propose an estimation method, and an associated estimation device DE, intended to allow a precise and reliable estimation of the maximum operating power pmf of a cellular battery BC of a vehicle V.

In the following, it is considered, by way of non-limiting example, that the vehicle V is of the automobile type. For example, it is a car, as illustrated in the . But the invention is not limited to this type of vehicle. It concerns any type of vehicle comprising a cellular battery connected to a main electrical circuit (or "high voltage") and capable of supplying or receiving electrical power. Thus, it concerns, for example, land vehicles (utility vehicles, campers, minibuses, coaches, trucks, motorcycles, road machinery, construction machinery, agricultural machinery, leisure machinery (snowmobile, kart), and tracked vehicles, for example), boats and aircraft.

Furthermore, it is considered in the following, as a non-limiting example, that the vehicle V 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).

We have schematically represented on the a vehicle V comprising an electric GMP transmission chain, an on-board network RB, a main electrical circuit CEP, a cellular battery BC, a converter CV, a service battery BS, and an estimation device DE according to the invention.

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

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 via the main electrical circuit CEP, and sometimes instead of this CV converter. For example, this service battery BS can be arranged in the form of a very low voltage type battery (typically 12 V, 24 V or 48 V). It is rechargeable at least by the CV current 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.

The main electrical circuit (or high voltage) CEP is connected, on the one hand, to the cellular battery BC, and, on the other hand, to electronic equipment, such as the converter CV and the electric motor MME. It also allows the recharging of the cellular battery BC by an external power source and temporarily coupled to a CR recharging connector of the vehicle V.

The transmission chain has a GMP which is, here, purely electric and therefore which includes, in particular, an electric motor MME. Here, the term “electric motor” means an electric machine arranged so as to provide torque to move the vehicle V when it is supplied with electrical energy, as well as possibly to recover torque in the transmission chain.

The operation of the transmission chain (and therefore of the GMP) is supervised by a CS supervision calculator.

The electric motor MME (here an electric motor) is here coupled to the cellular battery BC via the main electrical circuit CEP, in order to be supplied with electrical energy, as well as to supply this cellular battery BC with electrical energy, for example during a regenerative braking phase.

Furthermore, this electric motor MME is coupled to a motor shaft, to provide it with torque by rotational drive. Here, the motor shaft is coupled to a transmission shaft via a reducer RD, and this transmission shaft is coupled to a first train T1 (here of wheels), preferably via a differential DF.

This first train T1 is here located in the front part PVV of the vehicle V. 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 V.

The operation of the electric motor MME is controlled by an associated machine calculator CM which receives in particular each torque instruction defined by the supervision calculator CS and defining the output torque which the electric motor MME must provide or the input torque which the electric motor MME must recover.

The cell battery BC here powers the electric motor MME. It is therefore called the main (or traction) battery. It comprises N electrical energy storage cells CE, with N ≥ 2. Each cell (electrical energy storage) CE has a measurable cell voltage ucm and is possibly electrochemical (in this case it can, for example, be of the lithium-ion (or Li-ion) or Ni-Mh or Ni-Cd type). Also for example, the cell battery BC can be of the low voltage type (typically 450 V for illustration purposes). But it could be of the medium voltage or high voltage type. It should be noted, as illustrated non-limitingly on the , that CE cells can possibly be part of MC module(s).

Furthermore, the BC cell battery is (here) associated with a BB battery case which includes means for measuring voltage/current/internal temperature tib (not illustrated), and a CB battery calculator. This CB battery calculator centralizes the current measurements, the voltage measurements and the internal temperature measurements tib (inside the BC cell battery), and determines parameters of the BC cell battery based on these measurements, and in particular its internal resistance, its minimum voltage and its current state of charge (or SOC (“State Of Charge”)).

It should be noted, as illustrated without limitation on the , that the CV converter can be part of a CH charger electrically connected to the CR charging connector and comprising the CA charging calculator responsible within its vehicle V for at least controlling the charging of the cellular battery BC, whatever the mode.

It should also be noted that in the example illustrated without limitation on the the vehicle V also includes 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 stored in the service battery BS or produced by the converter CV, 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 CS supervision calculator of the GMP).

As mentioned above, the invention notably proposes an estimation method intended to enable the precise and reliable estimation of the maximum operating power pmf of the cellular battery BC.

This (estimation) method can be implemented at least partially by the estimation device DE (illustrated at least partially in FIGS. 1 and 2) which comprises for this purpose at least one processor PR1, for example a digital signal processor (or DSP), and at least one memory MD. This estimation device DE 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.

The MD memory is RAM in order to store instructions for the implementation by the processor PR1 of at least part of the 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 performing at least one electrical or electronic operation.

In the example illustrated non-limitingly in figures 1 and 2, the estimation device DE is part of the battery calculator CB. This is advantageous because it is the latter (CB) which controls the electrical power which is supplied by the cellular battery BC during a discharge phase and the electrical power which the cellular battery BC receives during a recharge (or regenerative) phase. But this is not obligatory. Indeed, the estimation device DE could comprise its own dedicated calculator, which is then coupled to the battery calculator CB, or could be part of another on-board calculator than the latter (CB), such as for example the supervision calculator CS.

As illustrated without limitation on the , the (monitoring) method, according to the invention, comprises a step 10-30 which is implemented when the vehicle V is awake and therefore its cellular battery BC is capable of supplying the main electrical circuit CEP with electrical power (discharge phase) or of receiving electrical power from the main electrical circuit CEP (recharge phase).

Step 10-30 of the method comprises a substep 20 in which one (the estimation device DE) estimates the maximum operating power pmf of the cellular battery BC by multiplying an estimated primary maximum power pmp by a limitation coefficient cl which is estimated by means of a chosen function f and having a parameter pn which is independent of the internal temperature tib in the cellular battery BC. This parameter pn is defined by a ratio between first du1 and second du2 differences, i.e. pn = du1/du2.

The primary maximum power pmp is, for example, estimated by the battery calculator CB as a function of at least the internal temperature tib of the cellular battery BC and the state of charge of the latter (BC). But in an alternative embodiment, the primary maximum power pmp could be estimated by the estimation device DE in a preliminary sub-step.

The first difference du1 is the result of the subtraction between an extreme cell voltage uce of the CE cells and a limit voltage of use (or in English cut-off voltage) ulu, i.e. du1 = uce - ulu.

The extreme cell voltage uce is chosen from all measured cell voltages ucm. For example, this extreme cell voltage uce can be either the smallest of all measured cell voltages ucm (and therefore the minimum cell voltage ucm at the instant considered) when the cell battery BC is in a discharge phase, or the largest of all measured cell voltages ucm (and therefore the maximum cell voltage ucm at the instant considered) when the cell battery BC is in a recharge phase.

The ulu usage limit voltage is a minimum (discharging) or maximum (recharging) cell voltage that is allowed to be reached, but which can nevertheless be exceeded by a lower value (discharging) or by a higher value (recharging) without risk of damage.

The second difference du2 is the result of the subtraction between a limiting starting voltage (or in English "derating voltage") udl and the usage limit voltage ulu, i.e. du2 = udl - ulu.

The limiting start voltage udl is a cell voltage from which we decide to start limiting the primary maximum power pmp estimated by the limiting coefficient cl. In other words, in a discharge phase we start limiting the primary maximum power pmp estimated by the limiting coefficient cl when the smallest (and therefore extreme) cell voltage uce becomes less than or equal to the limiting start voltage (discharge) udl. It should be noted that in a discharge phase as long as the smallest (and therefore extreme) cell voltage uce is greater than the limiting start voltage (discharge) udl, we use a limiting coefficient cl equal to one (1), which amounts to having a maximum operating power pmf equal to the estimated primary maximum power pmp.

In a recharge phase, we begin to limit the primary maximum power pmp estimated by the limitation coefficient cl when the highest (and therefore extreme) cell voltage uce becomes greater than or equal to the limitation (recharge) start voltage udl. It should be noted that in a recharge phase, as long as the highest (and therefore extreme) cell voltage uce is lower than the limitation (recharge) start voltage udl, we use a limitation coefficient cl equal to one (1), which amounts to having a maximum operating power pmf equal to the estimated primary maximum power pmp.

It will be understood that the parameter pn (= du1/du2 = (uce - ulu)/(udl - ulu)) is independent of the internal temperature tib because the variables uce, udl and ulu all vary according to this internal temperature tib. It will also be understood that the limitation coefficient cl is calibrated generically and optimized according to the internal temperature tib because the parameter pn includes a numerator ud1 which is a first difference or distance between voltages (uce - ulu) normalized by a denominator ud2 which is a second difference or distance between voltages (udl - ulu). Thus, there is no longer any need to use a very large memory to store a multitude of correspondence tables (or maps) for a multitude of different internal temperatures tib, just as we do not operate in open loop without taking into account the limit voltage of use ulu. This makes it possible to obtain a precise and reliable estimate of the limitation coefficient cl, which can protect against the risks of undervoltage and overvoltage, without this incurring an additional cost for the vehicle V.

For example, and as illustrated without limitation on the , step 10-30 may comprise a sub-step 10 in which one (the estimation device DE) determines the parameter pn, then estimates the limitation coefficient cl as a function of this determined parameter pn and of the function f.

For example, in substep 10 of step 10-30 one (the estimation device DE) can choose a function f which is linear when the second difference ud2 is less than or equal to a chosen threshold.

Also for example, in substep 10 of step 10-30 one (the estimation device DE) can choose a function f which is nonlinear when the second difference ud2 is greater than a chosen threshold. The latter is preferably the same as that mentioned in the previous paragraph. In this case, one can use a linear function f when the second difference ud2 is less than or equal to the chosen threshold and a nonlinear function f when the second difference ud2 is greater than this chosen threshold.

It should be noted that this threshold may possibly vary depending on whether we are in a discharge phase or a recharge phase.

The value of the (each) threshold can be determined in the laboratory in a development phase of a vehicle similar to vehicle V.

We have schematically illustrated in the diagram of the a first example c1 of a curve of evolution of a linear limitation coefficient cl as a function of the parameter pn, and a second example c2 of a curve of temporal evolution of a non-linear limitation coefficient cl as a function of the parameter pn. Here, the limitation coefficient cl has a value which varies between zero (0) and one (1). Similarly, given its expression, the parameter pn has a value which varies between zero (0) and one (1).

Note that also appear on the left of this diagram of the examples of respective positions of the voltages uce, udl, ulu and ur, involved in the invention, and in the case of a discharge phase. The voltage ur is a chosen recovery voltage (or in English "healing voltage"). We therefore have here ulu < uce < udl < ur (considering that uce (which is the smallest of the cell voltages) has not yet fallen below ulu).

For example, and as illustrated without limitation on the , step 10-30 may comprise a sub-step 30 in which the maximum operating power pmf is maintained (the estimation device DE triggers the maintenance of) at a constant value in the presence of a particular change in the extreme cell voltage uce and depending on whether the user is in a discharge phase or a recharge phase.

When in a discharge phase, the maximum operating power pmf is maintained (the estimation device DE triggers the maintenance of) at a constant value when the extreme cell voltage (here minimum) uce begins to increase again after a decrease phase and remains lower than the chosen recovery voltage ur.

When in a recharge phase, we maintain (the estimation device DE triggers the maintenance of) the maximum operating power pmf at a constant value when the extreme cell voltage (here maximum) uce begins to decrease again after a growth phase and remains higher than the chosen recovery voltage ur.

The optional operating mode described above and which can be implemented in a discharge phase, and which can be described as hysteresis, is schematically illustrated by the two diagrams in the which correspond to each other.

The first (upper) diagram includes an example of a time course of the extreme cell voltage uce.

The second (lower) diagram includes:

- a first example of curve c3 of the temporal evolution of the maximum operating power pmf when the limitation coefficient cl is not used (or when it is equal to one (1)), and in the presence of the temporal evolution of the extreme cellular voltage uce of the first diagram, and

- a second example of curve c4 of the temporal evolution of the maximum operating power pmf when using the limitation coefficient cl, and in the presence of the temporal evolution of the extreme cellular voltage uce of the first diagram.

In this illustrative example, as soon as the extreme (here minimum) cell voltage uce falls below the limiting (discharge) start voltage udl, a limiting coefficient cl less than one (1) is used, which causes a constant decrease (by xkW/second) of the maximum operating power pmf. Then, when the extreme (here minimum) cell voltage uce reaches a local minimum and starts to increase again, the maximum operating power pmf is kept constant. Then, when the extreme (here minimum) cell voltage uce falls above the recovery voltage ur, the constraint on the maximum operating power pmf is released, which makes the latter (pmf) tend towards the primary maximum power pmp. Then, when the extreme (here minimum) cell voltage uce falls below the limiting (discharge) start voltage udl, a limiting coefficient cl less than one (1) is used again, which causes a new constant decrease (of xkW/second) in the maximum operating power pmf. Then, when the extreme (here minimum) cell voltage uce reaches a local minimum again and starts to increase again, the maximum operating power pmf is kept constant. Then, if the extreme (here minimum) cellular voltage uce starts to decrease again and falls below the last local minimum, we again use a limitation coefficient cl less than one (1), which causes a new constant decrease (of xkW/second) of the maximum operating power pmf, this time towards the zero value (0 kW) to avoid going into a safety zone and thus avoid any risk of heating (or even fire) of the cellular battery BC.

This hysteresis mechanism is introduced up to above the limiting start voltage udl in discharge to avoid oscillations coming from an immediate recovery of the power following the application of a limiting coefficient cl less than one (1). This makes it possible to improve the robustness of the estimation of the power limitation. Indeed, the maximum operating power pmf only recovers once the extreme cell voltage uce passes above the recovery voltage ur in discharge.

The person skilled in the art will immediately deduce from the two diagrams of the the two diagrams corresponding to the operating mode with hysteresis, optional, which can be implemented in a recharging phase, by performing a horizontal mirror symmetry.

For example, and as illustrated without limitation on the , in sub-step 10 of step 10-30 we (the estimation device DE) can estimate a limitation coefficient cl which imposes:

- either a first constant decrease p1 of the maximum operating power pmf as long as the extreme cell voltage uce is lower than the usage limit voltage ulu (basic operating mode that could be described as “preventive” (php) and which is implemented between udl and ulu),

- either a second decrease p2 strictly greater than the first decrease p1 and increasing when a third difference ud3 decreases between the extreme cellular voltage uce and a forbidden limit voltage uli (specific operating mode that could be described as “curative” (phc) and which is implemented between ulu and uli).

For example, in substep 30 of step 10-30 the second decay p2 may vary nonlinearly as the third difference ud3 decays.

This optional curative operating mode results from the following observation. Theoretically, without any state of charge estimation error and without a strong internal temperature gradient tib within the MC modules, the estimated primary maximum power pmp should be zero when the extreme cell voltage uce reaches the usage limit voltage ulu (especially if the power limitation is activated at the right level). However, even if we seek to have a zero maximum operating power pmf when the maximum operating power pmf reaches the usage limit voltage ulu, residual power could still be available at low levels of cell voltage ucm in discharge (respectively high in recharge) because of the power variation slopes (xkW/second) of the real power imposed by the CS supervision calculator and certain communication delays with the CB battery calculator. It is therefore advantageous, in the event of crossing the limit voltage of use ulu, to significantly increase the power variation slopes (xkW/second) to tend as quickly as possible towards the maximum operating power pmf zero.

The basic (or preventive php) mode of operation between udl and ulu, and the specific (or curative phc) mode of operation between ulu and uli, are schematically illustrated in the diagram of the . As can be seen, in the basic operating mode (or preventive php) we impose on the primary maximum power pmp a first constant decrease p1 (via the limitation coefficient cl), for example equal to 4 kW/second, between the limitation start voltage udl and the usage limit voltage ulu. Then, we establish the specific operating mode (or curative phc) between the usage limit voltage ulu and the prohibited limit voltage uli. For example, we can impose a second decrease p2 (> p1) of exponential type, when we approach the prohibited limit voltage uli. For example, very close to the prohibited limit voltage uli we can impose a third decrease p3 (subpart of p2) between 100 kW/second and 200 kW/second. Instead of using a second exponential-type p2 decay, one could use a lookup table (or mapping).

It should also be noted, as illustrated without limitation on the , that the battery calculator CB (or the calculator of the estimation device DE) can also comprise a mass memory MM1, in particular for storing the current extreme cell voltage uce and any estimated primary maximum power pmp and current internal temperature tib, as well as any intermediate data involved in all its calculations and processing. Furthermore, this battery calculator CB (or the calculator of the estimation device DE) can also comprise an input interface IE for receiving at least the current extreme cell voltage uce and any estimated primary maximum power pmp and current internal temperature tib, for using 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 DE estimation device calculator) may also include an IS output interface, in particular to deliver the maximum operating power pmf.

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 estimation method described above to precisely and reliably estimate the maximum operating power pmf of the cellular battery BC of the vehicle V.

The invention offers several advantages, including:

- protection of the BC cell battery by avoiding its under-discharges and overcharges,

- protection against failures of the CB battery calculator and minimization of occurrences of opening of the contactors (or switches) of the isolation device associated with the BC cellular battery,

- avoidance of premature aging of the BC cell battery due to the reduction in the occurrence of passage between the usage limit voltage ulu and the prohibited limit voltage uli,

- better respect for the lifespan of electronic and chemical components,

- a significant reduction in calibration costs.

Claims (10)

Method for estimating a maximum operating power for a cellular battery (BC) of a vehicle (V) comprising N cells (CE) each having a cellular voltage, with N ≥ 2, said method comprising a step (10-30) in which said maximum operating power is estimated by multiplying an estimated primary maximum power by an estimated limitation coefficient, characterized in that in said step (10-30) said limitation coefficient is estimated by means of a chosen function and having a parameter independent of an internal temperature in said cellular battery (BC) and defined by a ratio between a first difference, between an extreme cellular voltage of said cells (CE) and a usage limit voltage, and a second difference, between a limiting start voltage and said usage limit voltage. Method according to claim 1, characterized in that in said step (10-30) said extreme cell voltage is either a minimum cell voltage when said cellular battery (BC) is in a discharge phase, or a maximum cell voltage when said cellular battery (BC) is in a recharge phase. Method according to claim 1 or 2, characterized in that in said step (10-30) a linear function is chosen when said second difference is less than or equal to a chosen threshold. Method according to claim 1 or 2, characterized in that in said step (10-30) a non-linear function is chosen when said second difference is greater than a chosen threshold. Method according to one of claims 1 to 4, characterized in that in said step (10-30) said maximum operating power is maintained at a constant value either when in a discharge phase of said cellular battery (BC) said extreme cellular voltage begins to increase again after a decrease phase and remains lower than a chosen recovery voltage, or when in a recharge phase of said cellular battery (BC) said extreme cellular voltage begins to decrease again after a increase phase and remains higher than said chosen recovery voltage. Method according to one of claims 1 to 5, characterized in that in said step (10-30) a limitation coefficient is estimated imposing either a first constant decrease in said maximum operating power as long as said extreme cellular voltage is lower than said limit usage voltage, or a second decrease strictly greater than said first decrease and increasing when a third difference between said extreme cellular voltage and a prohibited limit voltage decreases. Method according to claim 6, characterized in that in said step (10-30) said second decrease varies non-linearly as said third difference decreases. Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the estimation method according to one of claims 1 to 7, in a vehicle (V) comprising a cellular battery (BC) comprising N cells (CE) each having a cellular voltage, with N ≥ 2, for estimating a maximum operating power for said cellular battery (BC). Estimation device (DE) for a vehicle (V) comprising a cellular battery (BC) comprising N cells (CE) each having a cellular voltage, with N ≥ 2, said estimation device (DE) comprising at least one processor (PR1) and at least one memory (MD) arranged to perform the operations consisting in estimating a maximum operating power for said cellular battery (BC) by multiplying an estimated primary maximum power by an estimated limitation coefficient, characterized in that said processor (PR1) and memory (MD) are further arranged to perform the operations consisting in estimating said limitation coefficient by means of a chosen function and having a parameter independent of an internal temperature in said cellular battery (BC) and defined by a ratio between a first difference, between an extreme cellular voltage of said cells (CE) and a usage limit voltage, and a second difference, between a limiting start voltage and said usage limit voltage. Vehicle (V) comprising a cellular battery (BC) comprising N cells (CE) each having a cellular voltage, with N ≥ 2, characterized in that it further comprises an estimation device (DE) according to claim 9.