WO2023144461A1

WO2023144461A1 - Monitoring cell overvoltages in a cellular battery of a system

Info

Publication number: WO2023144461A1
Application number: PCT/FR2022/052153
Authority: WO
Inventors: Olivier BALENGHIEN
Original assignee: Psa Automobiles Sa
Priority date: 2022-01-25
Filing date: 2022-11-22
Publication date: 2023-08-03
Also published as: FR3132147B1; FR3132147A1

Abstract

The invention relates to a method for monitoring voltages across the terminals of electrical energy storage cells which are part of a cellular battery in a system. Said method comprises a step (10-40) in which, in a phase of discharging the cellular battery, when at least one of the determined voltages exceeds at least one first selected threshold, at least one action is performed in the system depending on the exceedance.

Description

DESCRIPTION

TITLE: CELL OVERVOLTAGE MONITORING OF A CELLULAR SYSTEM BATTERY

The present invention claims the priority of French application No. 2200623 filed on January 25, 2022, the content of which (text, drawings and claims) is incorporated herein by reference.

Technical field of the invention

The invention relates to systems comprising at least one cellular battery supplying electrical energy to at least one electrical machine, and more specifically the monitoring within such systems of overvoltages in the cells of the cellular batteries.

State of the art

Certain systems, such as for example certain vehicles (possibly of the automobile type), comprise at least one electric machine supplied with electric energy by a cellular battery, that is to say comprising at least two electric 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 vehicles these cellular batteries are generally so-called "main" (or traction) batteries responsible for supplying electric current to an on-board network of their vehicle, via a converter, and at least one electric motor machine of the group powertrain (or GMP). But, at least in vehicles, these cellular batteries could be so-called "service" batteries of the very low voltage type (typically between 12 V and 48 V) and responsible for supplying electric current to an on-board network of the vehicle in l the absence of a main battery (and therefore of an electric motor) either instead of or in addition to a main battery of the vehicle.

In the following and the foregoing, the term "on-board network" means an electrical power supply network to which equipment (or electrical (or electronic) components consuming electrical energy.

As those skilled in the art know, in a cellular battery at least one of the cells can sometimes be subject to an overvoltage, in particular during a discharge phase. Here, the term "cell having an overvoltage" means a cell having a higher voltage than most of the other identical cells of its cellular battery, and therefore having a high probability of being subject to premature ageing.

These overvoltages are likely to reduce the life of the cells of the cellular battery, and can cause, when their duration is relatively long, damage which can be the cause of a fire in the vehicle and/or electrocution of passenger(s).

It has been proposed in patent document US-A1 6,992,463 to monitor cell voltages, in order to isolate the cell battery from the electric machine in the event of detection of an overvoltage at the level of a cell, to prevent the battery cellphone catches fire. A disadvantage of this solution lies in the fact that the detection of an overvoltage induces an immediate shutdown of the operation of the system (and therefore immobilization in the case of a vehicle) and the on-site intervention of at least one technician. an after-sales service, which proves penalizing for the users of this system since suddenly they can no longer use it. This is all the more unfortunate as the degradation of a cell is progressive and relatively slow.

There is therefore a real need to detect the degradation of a cellular battery cell of a system and to inform the users of this system before the latter is stopped by the isolation of its cellular battery.

Presentation of the invention

In particular, it proposes for this purpose a monitoring method intended to be implemented in a system comprising an electric machine supplied with electric energy by a cellular battery comprising N electric energy storage cells, with N>1, and N sensors determining respectively N voltages across these N cells.

This monitoring method is characterized in that it comprises a step in which, when in a discharging phase of the cellular battery at least one of the determined voltages exceeds at least a first chosen threshold, at least one action depending on the overrun is carried out in the system.

The expression “function of the overshoot” here means function of the amplitude of the overshoot. Thus, in the event of an overvoltage, it is now possible to define severity levels depending on the amplitude of the overrun, which makes it possible to prevent the cellular battery from being isolated from the electrical machine without at least one other action having been carried out beforehand. in the system.

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

- in its step, it is possible to perform in the system at least one action depending on the overrun when at least one of the determined voltages exceeds at least the first threshold chosen for a duration chosen depending on the overrun;

- in its step, when the overrun is greater than the first threshold s1 and less than or equal to a second chosen threshold greater than the first threshold, it is possible to perform in the system at least a first action consisting in generating an alert for a user of the system of a need to have the cellular battery checked and depending on the overrun, and when the overrun is greater than at least the second threshold, the first action and at least one other action chosen from a group comprising a reduction of an electric power supplied by the cell battery to the electric machine and an isolation of the cell battery from the electric machine;

- in the presence of the last option, in its step, when the overrun is greater than the second threshold and less than or equal to a third threshold greater than the second threshold, the first action and a second action consisting in reducing the electric power supplied by the cellular battery to the electric machine, and when the overrun is greater than the third threshold, the first and second actions and a third action consisting of isolate the cellular battery from the electrical machine;

- also in the presence of the last option, in its step, when at least one of the determined voltages exceeds the first threshold, it is possible to perform in the system at least one other first action consisting in recording a fault code representative of the overrun;

- in the presence of one of the last two sub-options, in its step, i) it is possible to stop isolating the cellular battery from the electric machine when the overshoot becomes lower than the third threshold but is higher than a fourth threshold higher than the second threshold for a chosen duration, ii) it is possible to stop reducing the electrical power supplied when the overshoot becomes lower than the second threshold but is greater than a fifth threshold higher than the first threshold for another chosen duration, and ill) it is possible to stop reducing generating the alert when the overrun becomes lower than a sixth threshold lower than the first threshold for yet another chosen duration;

- also in the presence of the last option, in its step, the electrical power supplied can be reduced by making it decrease in a time interval depending on the overrun, down to a value chosen depending on the overrun.

The invention also proposes a computer program product comprising a set of instructions which, when it is executed by processing means, is capable of implementing a monitoring method of the type presented above for monitoring voltages at the terminals of electrical energy storage cells forming part of a cellular battery equipping a system comprising sensors respectively determining these voltages.

The invention also proposes a monitoring device intended to equip a system comprising an electric machine supplied with electric energy by a cellular battery comprising N electric energy storage cells, with N>1, and N sensors respectively determining N terminal voltages of the N cells.

This monitoring device is characterized in that it comprises at least one processor and at least one memory arranged to perform the operations consisting, when in a discharging phase of the cellular battery at least one of the determined voltages exceeds at least a first chosen threshold, in triggering the performance in the system of at least one action depending on the overrun.

The invention also proposes a system comprising, on the one hand, an electrical machine supplied with electrical energy by a cellular battery comprising N electrical energy storage cells, with N>1, and N sensors respectively determining N voltages at the terminals of these N cells, and, on the other hand, a monitoring device of the type presented above. For example, this system can constitute a vehicle, possibly of the automobile type, and in which the electrical machine is a driving machine belonging to a powertrain and producing torque to move it.

Brief description of figures

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

[Fig. 1] schematically and functionally illustrates an exemplary embodiment of a system constituting a vehicle comprising a GMP, with an electric motor machine powered by a main cellular battery, and a monitoring device according to the invention,

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

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

Detailed description of the invention

The aim of the invention is in particular to propose a monitoring method, and an associated monitoring device DS, intended to allow the monitoring of voltages te of electrical energy storage cells CE of a cellular battery BP equipping a system S. In what follows, it is considered, by way of non-limiting example, that the system S is a vehicle of the automobile type. It is for example a car, as illustrated in FIG. But the invention is not limited to this type of system. It relates in fact to any type of system comprising at least one electrical machine supplied with electrical energy by at least one rechargeable cellular battery (regardless of the mode). Thus, it concerns, for example, land vehicles (utility vehicles, motorhomes, minibuses, coaches, trucks, motorcycles, road construction machinery, construction machinery, agricultural machinery, leisure machinery (snowmobile, kart), and caterpillar(s), for example), boats, aircraft, installations (possibly of the industrial type), and buildings.

Furthermore, it is considered in what follows, by way of non-limiting example, that the vehicle S comprises a powertrain (or GMP) of the all-electric type (and therefore whose traction is ensured exclusively by at least one electric motor machine MME associated with at least one BP cellular battery). But the GMP could be of the hybrid type (thermal and electric) or purely thermal.

In addition, it is considered in what follows, by way of non-limiting example, that the monitored cellular battery BP is a main (or traction) battery. But the monitored cellular battery could be a service battery (possibly rechargeable via a converter supplied with electrical energy by a main battery).

There is schematically represented in FIG. 1 a system S constituting a motor vehicle comprising an electric GMP transmission chain, a main cellular battery BP, and a monitoring device DS according to the invention.

The transmission chain has a GMP which is, here, purely electrical and therefore which comprises, in particular, an electric drive machine MME, a motor shaft AM, and a transmission shaft AT. “Electric driving machine” is understood here to mean an electric machine arranged to supply torque to move the vehicle S and possibly to recover (or take) recoverable torque from the transmission chain to generate a recoverable (electrical) current transformed into electrical energy stored in the main cell battery BP in a regenerative braking phase.

The operation of the GMP is supervised by a supervision computer CS.

The electric driving machine MME is coupled to the main cellular (or traction) battery BP, in order to be supplied with electrical energy during a driving phase, and possibly to supply this main cellular battery BP with recuperative (electrical) current 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 D1.

This first train T1 is here located in the front part PW of the vehicle V. But in a variant this first train T 1 could be the one which is here referenced T2 and which is located in the rear part PRV of the vehicle V.

The main cellular battery BP comprises N electrical energy storage cells CE, with N > 1. Here N is equal to 54, but it can take any value greater than or equal to two. It will be noted that the (electrical energy storage) cells CE can optionally be grouped together in modules MC which are identical or different from each other, as illustrated without limitation in FIG.

For example, CE (electrical energy storage) cells can be electrochemical. Thus, they can, for example, be of the lithium-ion (or Li-ion) or Ni-Mh or Ni-Cd type.

Also for example, the main cellular battery BP can be of the low voltage type (typically 450 V by way of illustration). But it could be medium voltage or high voltage.

The N cells CE are respectively associated with N sensors (not shown) responsible for determining respectively N voltages te at their terminals.

Furthermore, the main cellular battery BP is (here) associated with a battery box BB which notably comprises an isolation device DI, voltage/current measuring means (not shown), and a battery computer CB. The isolation device DI is arranged so as to isolate, if necessary, the main cellular battery BP from at least the electric drive machine MME. It comprises for example contactors (or switches), possibly based on MOSFET(s), which can each be placed in an open (or off) state or a closed (or on) state.

The battery computer CB centralizes the current measurements and the voltage measurements (in particular those (te) which are determined by the N sensors (associated respectively with the N cells CE) and monitored), and determines parameters of the main cellular battery BP according to these measurements, and in particular its internal resistance, its minimum voltage and its current state of charge (or SOC (“State Of Charge”)). Furthermore, the battery computer CB also exchanges information with the supervision computer CS of the GMP.

As mentioned above, the invention proposes in particular a monitoring method intended to allow monitoring of the voltages te of the cells CE (here of the main cell battery BP).

This (monitoring) method can be implemented at least partially by the monitoring device DS (illustrated in FIGS. 1 and 2) which comprises for this purpose at least one processor PR1, for example of digital signal (or DSP (“ Digital Signal Processor”)), and at least one MD memory. This monitoring device DS can therefore be produced in the form of a combination of electrical or electronic circuits or components (or “hardware”) and software modules (or “software”). By way of example, it may be a microcontroller.

The memory MD is live in order to store instructions for the implementation by the processor PR1 of at least part of the monitoring method. The processor PR1 can comprise integrated (or printed) circuits, or else several integrated (or printed) circuits connected by wired or wireless connections. By integrated (or printed) circuit is meant any type of device capable of performing at least one electrical or electronic operation.

In the example illustrated without limitation in FIGS. 1 and 2, the monitoring device DS forms part of the battery computer CB (and therefore of the battery box BB). But this is not mandatory. In fact, the device monitoring DS could comprise its own dedicated computer, which is then coupled to the battery computer CB.

As illustrated without limitation in FIG. 3, the (monitoring) method, according to the invention, comprises a step 10-40 which is implemented in the system (here a vehicle) S when the latter (S) is in a discharging phase of its main cellular battery BP.

In a sub-step 10 of step 10-40, the N sensors respectively determine the N voltages te at the terminals of the N cells CE, and communicate them to the battery computer CB, which transmits them to the monitoring device DS.

Then, in a sub-step 20 of step 10-40, it (the monitoring device DS) determines from among the N voltages te received whether one of them exceeds at least a first chosen threshold s1.

If not (and therefore when all the N voltages te are less than or equal to the first threshold s1 ), sub-step 10 is performed again.

On the other hand, in the affirmative (and therefore when at least one voltage te exceeds the first threshold s1 ), one carries out (the monitoring device DS triggers the realization) in the system S at (of at least) one function action of the overrun, in a sub-step 30 of step 10-40.

It will be understood that it is at least the processor PR1 and memory MD of the monitoring device DS which are arranged to perform the operations consisting in monitoring the voltages te, and, when at least one voltage te exceeds the first threshold s1, in triggering the performance in the system S of at least one action which is a function of the overrun.

It is recalled that the expression “function of the overshoot” here means function of the amplitude of the overshoot.

Each action being a function of the overrun (and therefore of its amplitude), it is now possible to define severity levels depending on the amplitude of the overrun, and thus prevent the cellular battery BP from being isolated from the electric drive machine MME without unless another action has been previously performed in the system S. This is made possible by the fact that the degradation of a CE cell (which induces an overvoltage) is progressive and relatively slow (and therefore induces a gradual increase in the amplitude of the overvoltage (and therefore of the overshoot)).

Preferably, to avoid performing at least one action unnecessarily when a voltage te exceeds at least the first threshold s1 for a very short time, for example due to a voltage measurement error by a sensor or a very sudden insignificant variation of a voltage te, the monitoring device DS only decides to carry out at least one action on condition that a voltage te exceeds at least the first threshold s1 for a duration chosen as a function of the overrun.

For example, when a voltage te only exceeds the first threshold s1 (but not another threshold s2 or s3 defined later) the duration chosen for the overshoot can be between 1 s and 10 s. By way of illustrative example, this selected duration may be equal to 4 s. But we can use other values for this duration.

As mentioned above, at least one other threshold s2 can be used as an option in order to define two levels of severity depending on the amplitude of the overrun. This second threshold s2 is greater than the first threshold s1.

In the presence of this last option, in sub-step 30 of step 10-40, when the overrun is greater than the first threshold s1 and less than or equal to the second threshold s2, one carries out (the monitoring device DS triggers the realization ) in the system S at least (of at least) a first action which consists in generating an alert for a user of the system S of a need to have the cell battery BP checked and function of the overrun. In the case of a vehicle, the alert concerns at least its driver, and the verification is done in an after-sales service. This first situation corresponds to a first level of severity (the lowest because the overrun remains low, and therefore only requires an alert from the user (or driver)).

But in sub-step 30 of step 10-40, when the overrun is greater than at least the second threshold s2, one performs (the monitoring device DS triggers the execution) in the system S (of) the first action and at least (of at least) one other action which is chosen from among the reduction of the electric power supplied by the cellular battery BP to the electric motor machine MME and an isolation of the cellular battery BP from the electric driving machine MME. This situation corresponds to a second or third level of severity.

For example, the user (or driver) can be alerted by a simple "service" light on or by a message (possibly dedicated to the problem detected) which is displayed on at least one screen of the system S (for example of the dashboard in the case of a vehicle) or on the screen of a smart phone (or "smartphone") of the user (or driver), and/or broadcast by at least one loudspeaker speaker of the S system or this smartphone.

Also as mentioned above, yet another threshold s3 can be used as an option in order to define three levels of severity depending on the amplitude of the overrun. This third threshold s3 is greater than the second threshold s2.

In the presence of this last option, in sub-step 30 of step 10-40, when the overrun is greater than the second threshold s2 and less than or equal to the third threshold s3, one carries out (the monitoring device DS triggers the execution ) in the system S (of) the (each) first action and one (of a) second action which consists in reducing the electric power which is supplied by the cellular battery BP to the electric motor machine MME. This second situation corresponds to a second level of severity (intermediate because the overrun is relatively high, and therefore requires not only the alert of the user (or driver), but also a reduction in the electrical power supplied to avoid damaging the BP cellular battery).

But in sub-step 30 of step 10-40, when the overshoot is greater than the third threshold s3, the first and second actions and one (of a) third action which consists in isolating the cellular battery BP from the electric drive machine MME. This third situation corresponds to a third level of severity (the highest because the overrun is important, and therefore requires not only the alert of the user (or driver), but also a reduction in the electrical power supplied to avoid damage the BP cellular battery, then the isolation of the BP cellular battery for safety). Preferably, to avoid performing at least one action unnecessarily when a voltage te is between the second s2 and third s3 thresholds for a very short time, for example due to a voltage measurement error by a sensor or d 'a very sudden, insignificant variation of a voltage te, the monitoring device DS decides on the performance of at least one action only on condition that a voltage te is between the second s2 and third s3 thresholds for a duration chosen according to the overrun. For example, when a voltage te is between the second s2 and third s3 thresholds, the selected overrun duration can be between 500 ms and 1500 ms. By way of illustrative example, this chosen duration can be equal to 1000 ms. But we can use other values for this duration.

It will be noted that the reduction in the electrical power supplied in the presence of the second level of gravity can be partial (that is to say up to a non-zero value) or total (that is to say up to the zero value which corresponds to a complete interruption of the supply of electric power by the electric drive machine MME). It will also be noted that the reduction in the electrical power supplied can be gradual over a chosen time interval (in order to avoid having to subject the electrical components (or equipment) concerned to excessive voltage gradients and current gradients which could damage them), or instantaneous (initial value, then zero final value). When the reduction is gradual, the time interval can, for example, have a duration between 30 s and 90 s. By way of illustrative example, this duration of the time interval may be equal to 60 s. But we can use other values for this duration.

In the presence of the second level of gravity when the reduction in the electrical power supplied is partial, the final electrical power can, for example, be between 5 kW and 10 kW. By way of illustrative example, this final electrical power may be equal to 8.5 kW. But other values can be used for this final electrical power.

Also preferably, to avoid performing at least one action unnecessarily when a voltage te is greater than the third threshold s3 for a very short time, for example due to a voltage measurement error by a sensor or a very sudden insignificant variation of a voltage te, the monitoring device DS decides on the performance of at least one action only on condition that a voltage te is greater than the third threshold s3 for a duration chosen as a function of the overrun.

For example, when a voltage te is greater than the third threshold s3, the selected overshoot duration can be between 100 ms and 1000 ms. By way of illustrative example, this selected duration may be equal to 500 ms. But we can use other values for this duration.

It will be noted that the reduction in the electrical power supplied in the presence of the third level of gravity is preferably total (that is to say down to the zero value which corresponds to a complete interruption of the supply of electric power by the machine electric motor MME). It will also be noted that the reduction in the electrical power supplied can be gradual over a chosen time interval (in order to avoid having to subject the electrical components (or equipment) concerned to excessive voltage gradients and current gradients which could damage them), or instantaneous (initial value, then zero final value). When the reduction is gradual, the time interval can, for example, have a duration between 10 ms and 200 ms. By way of illustrative example, this duration of the time interval may be equal to 100 ms. But we can use other values for this duration.

Also for example, the isolation of the main battery BP of the electric drive machine MME can be done by means of the isolation device DI which couples in particular the latter (BP and MME) and of which at least some of the contactors (or switches) are placed in their open (or non-conducting) state.

This option can possibly take place in two phases. In a first phase, the monitoring device DS can trigger the transmission to the monitoring computer CS of a request for authorization to open the contactors (or switches) of the isolation device DI. This transmission is ensured here by the battery computer CB. Then, if after a chosen duration the monitoring device DS has not received a response to its authorization request, it can trigger in a second phase, on its own initiative, the opening of the contactors (or switches ) of isolation device DI for electrically isolating the main battery BP from the electric drive machine MME.

For example, this last chosen duration can be between 500 ms and 1500 ms. By way of illustrative example, this last chosen duration can be equal to 1000 ms. But other values can be used for this last duration.

For example, the first threshold s1 can be between 4.18 V and 4.22 V. By way of illustrative example, this first threshold s1 can be equal to 4.2 V.

Also for example, the second threshold s2 can be between 4.23 V and 4.27 V. By way of illustrative example, this second threshold s2 can be equal to 4.25 V.

Also for example, the third threshold s3 can be between 4.3 V and 4.4 V. By way of illustrative example, this third threshold s3 can be equal to 4.35 V. It will also be noted that when a voltage te exceeds the first threshold s1, it is possible to perform (the monitoring device DS can trigger the production) in the system S at least (of at least) another first action which consists in recording at least one fault code representative of the overrun ( and therefore of the detected problem). In other words, in the presence of the first level of severity, at least one first fault code is recorded, in the presence of the second level of severity, at least one second fault code is recorded, and in the presence of the third level of severity, at least a third fault code. For example, after each occurrence of a severity level, a fault code can be stored in a (possibly dead) memory of the battery computer CB, and the supervision computer CS observing the storage of this fault code can possibly in turn store another fault code in a memory (possibly ROM) that it understands.

It will also be noted that it is possible to provide a fourth level of severity associated with a seventh threshold s7 comprised between the first s1 and second s2 thresholds. In the presence of this last option, in sub-step 30 of step 10-40, when the overrun is greater than the seventh threshold s7 and less than or equal to the second threshold s2, one carries out (the monitoring device DS triggers the execution ) in the system S at least of (of at less) the first action which consists in generating an alert for a user of the system S of a need to have the cell battery BP checked and function of the overrun. This last situation corresponds to a fourth level of severity (intermediate between the first and second levels of severity).

For example, the seventh threshold s7 can be between 4.2 V and 4.24 V. By way of illustrative example, this seventh threshold s7 can be equal to 4.22 V.

Preferably, to avoid performing at least one action unnecessarily when a voltage te is greater than the seventh threshold s7 and less than or equal to the second threshold s2 for a very short time, for example due to a voltage measurement error by a sensor or a very sudden, insignificant variation in a voltage te, the monitoring device DS only decides to perform at least one action on condition that the aforementioned voltage te is between the seventh s7 and second s2 thresholds for a duration chosen according to the overrun. For example, this chosen overrun duration can be between 2 s and 5 s. By way of illustrative example, this selected duration may be equal to 3 s. But we can use other values for this duration.

It will also be noted that when a voltage te is between the seventh s7 and second s2 thresholds, it is possible to perform (the monitoring device DS can trigger the production) in the system S at least (of at least) another first action which consists in recording at least one fault code representative of the overrun (and therefore of the problem detected). In other words, in the presence of the fourth level of severity, at least one first fault code representative of the overrun (and therefore of the detected problem) can be recorded.

It should also be noted that the user (or driver) alert can be a function of the detected overrun and therefore of the current level of severity. Thus, in the presence of the first level of severity or of the possible fourth level of severity, the alert can be given by lighting the service warning light when the S system is a vehicle. In the presence of the second or third level of severity, the alert can be given by lighting the stop light when the S system is a vehicle.

It will also be noted that a recovery mode can be provided in which reduces, possibly to zero, the number of actions performed when the overrun decreases.

In the presence of this last option, step 10-40 comprises a sub-step 40 in which:

- isolating the main battery BP from the electric drive machine MME ceases when the overrun becomes lower than the third threshold s3 but is higher than a fourth threshold s4 which is higher than the second threshold s2 for a chosen duration dr3, or

- the electrical power supplied is stopped when the overrun becomes lower than the second threshold s2 but is higher than a fifth threshold s5 which is higher than the first threshold s1 for another chosen duration dr2, or

- we stop generating the alert when the overrun becomes lower than a sixth threshold s6 lower than the first threshold s1 for yet another chosen duration dr1 .

For example, the fourth threshold s4 can be between 4.18 V and 4.22 V. By way of illustrative example, this fourth threshold s4 can be equal to 4.2 V.

Also for example, the fifth threshold s5 can be between 4.12 V and 4.16 V. By way of illustrative example, this second threshold s2 can be equal to 4.14 V.

Also for example, the sixth threshold s6 can be between 4.07 V and 4.11 V. By way of illustrative example, this sixth threshold s6 can be equal to 4.09 V. Also for example, each of the durations dr1 to dr3 can be between 3000 ms and 5000 ms. By way of illustrative example, this last chosen duration can be equal to 4000 ms. But other values can be used for these durations dr1 to dr3.

It will also be noted, as illustrated without limitation in FIG. 2, that the battery computer CB (or the dedicated computer of the monitoring device DS) can also include a mass memory MM1, in particular for the temporary storage of the values of the N voltages te monitored and any intermediate data involved in all its calculations and processing. Furthermore, this battery computer CB (or the dedicated computer of the monitoring device DS) can also comprise an input interface IE for the reception of at least the values of the N voltages te monitored in order 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 processor of digital signal PR2. In addition, this battery computer CB (or the dedicated computer of the monitoring device DS) can also comprise an output interface IS, in particular for delivering orders or messages for reducing the electrical power supplied or for canceling a reduction in the electrical power supplied, or messages or orders for isolation or end of isolation, or messages containing fault codes, or even service (or alert) messages for the user.

It will also be noted that the invention also proposes a computer program product (or computer program) comprising a set of instructions which, when it is executed by processing means of the electronic circuit (or hardware) type, such as for example the processor PR1 is capable of implementing the monitoring method described above for monitoring voltages at the terminals of electrical energy storage cells CE forming part of the cellular battery BP of the system S.

Claims

1. Monitoring method for a system (S) comprising an electrical machine (MME) supplied with electrical energy by a cellular battery (BP) comprising N electrical energy storage cells (EC), with N>1, and N sensors respectively determining N voltages at the terminals of said N cells (CE), characterized in that it comprises a step (10-40) in which, when in a discharging phase of said cellular battery (BP), at least one of said voltages determined exceeds at least a first chosen threshold, in said system (S) at least one action depends on the overrun.

2. Method according to claim 1, characterized in that in said step (10-40) is performed in said system (S) at least one action function of said overrun when at least one of said determined voltages exceeds at least said first threshold chosen for a duration chosen according to said overrun.

3. Method according to claim 1 or 2, characterized in that in said step (10-40), when said overrun is greater than said first threshold s1 and less than or equal to a second chosen threshold greater than said first threshold, in said system (S) at least a first action consisting in generating an alert for a user of said system (S) of a need to have said cellular battery (BP) checked and function of said overrun, and when said overrun is greater than at least said second threshold, said first action and at least one other action chosen from a group comprising a reduction of an electric power supplied by said cellular battery (BP) to said electric machine (MME) and an isolation of said cellular battery (BP) of said electric machine (MME).

4. Method according to claim 3, characterized in that in said step (10-40), when said overrun is greater than said second threshold and less than or equal to a third threshold greater than said second threshold, in said system (S) said first action and a second action consisting in reducing said electric power supplied by said cellular battery (BP) to said electric machine (MME), and when said exceeding is greater than said third threshold, said first and second actions and a third action consisting in isolating said cellular battery (BP) from said electrical machine (MME) are carried out in said system (S).

5. Method according to claim 3 or 4, characterized in that in said step (10-40), when at least one of said determined voltages exceeds said first threshold, in said system (S) at least another first action consisting in recording a fault code representative of said overrun.

6. Method according to claim 4 or 5, characterized in that in said step (10-40) i) isolating said cellular battery (BP) from said electric machine (MME) ceases when said overshoot becomes lower than said third threshold but is greater than a fourth threshold greater than said second threshold for a chosen duration, ii) said electrical power supplied is stopped being reduced when said overrun becomes less than said second threshold but is greater than a fifth threshold greater than said first threshold for another chosen duration , and ill) said alert is ceased to be generated when said overrun becomes less than a sixth threshold below said first threshold for yet another chosen duration.

7. Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the monitoring method according to one of claims 1 to 6 for monitoring voltages at the terminals of electrical energy storage cells (CE) forming part of a cellular battery (BP) equipping a system (S) comprising sensors respectively determining said voltages.

8. Monitoring device (DS) for a system (S) comprising an electric machine (MME) supplied with electric energy by a cellular battery (BP) comprising N electric energy storage cells (CE), with N>1, and N sensors respectively determining N voltages at the terminals of said N cells (CE), characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to perform the operations consisting, when in a phase of discharge of said cellular battery (BP) at least one of said determined voltages exceeds at least a first chosen threshold, to trigger the realization in said system (S) of at least least one action depending on the overrun.

9. System (S) comprising an electrical machine (MME) supplied with electrical energy by a cellular battery (BP) comprising N electrical energy storage cells (EC), with N>1, and N sensors respectively determining N voltages at the terminals of said N cells (CE), characterized in that it further comprises a monitoring device (DS) according to claim 8.

10. System according to claim 9, characterized in that it constitutes a vehicle in which said electric machine (MME) is a driving machine belonging to a powertrain and producing torque to move it.