FR3119712A1 - MONITORING THE STATE OF GAS EXCHANGES IN A SYSTEM BATTERY - Google Patents

Abstract

A control device (DC) controls a battery (BR) equipping a system (S), having a variable internal pressure, surrounded by air having a so-called external and variable pressure, and comprising an overpressure valve (VS) charged with balancing these internal and external pressures. This device (DC) is arranged to determine a first difference between the internal and external pressures, to determine a state of the battery (BR) representative of its gas exchanges with the outside, as a function of this first determined difference, and to decide to trigger, or not to trigger, in the system (S) at least one alert as a function of this determined state. Figure 1

Description

MONITORING THE STATE OF GAS EXCHANGES IN A SYSTEM BATTERY

Technical field of the invention

The invention relates to the batteries which are fitted to certain systems, and more specifically to the control of the state of gas exchanges with the exterior of such batteries.

State of the art

Certain systems, such as for example certain vehicles, possibly of the automotive type, comprise at least one battery (possibly rechargeable and possibly modular) and comprising a box in which there is a variable internal pressure and comprising a pressure relief valve (or “venting”) charged to balance this internal pressure with the external pressure (external).

This pressure relief valve usually includes a membrane allowing only air molecules to pass in both directions to ensure the pressure balance between the inside and the outside of the housing, and which can rupture (or burst) when the pressure internal becomes greater than a predefined threshold in order to allow emergency degassing.

Ensuring this balance between internal and external pressures is important when in some systems the internal pressure may vary due to altitude change and/or temperature change and/or gas generation inside the box.

In addition, the case must remain perfectly sealed against liquids in order to avoid the creation of short circuits likely to trigger a thermal runaway resulting in overheating or even a fire. Therefore, it is important that the membrane is only ruptured (or burst) in an emergency, but also that the seals of the housing are not damaged and that the latter is not punctured following an accident. or a violent shock (for example due to a stone or a protuberance), which can occur when the system is a vehicle.

Currently, there is no known solution for controlling gas exchange with the outside of the battery, and therefore it may happen that the internal pressure increases significantly, for example due to clogging of the pressure relief valve. making it impossible to evacuate air or gases generated internally, or that the battery is no longer sealed, without the users of the battery being informed, which can prove to be (very) dangerous.

The aim of the invention is therefore in particular to improve the situation by controlling the state of gas exchanges with the exterior of the battery.

Presentation of the invention

It proposes in particular for this purpose a control device intended to control a battery equipping a system, having a variable internal pressure, surrounded by air having a so-called external and variable pressure, and comprising a pressure relief valve responsible for balancing these pressures. internal and external.

This control device is characterized in that it comprises at least one processor and at least one memory arranged to perform the operations consisting of:

- to determine a first difference between the internal and external pressures,

- to determine a state of the battery representative of its gas exchanges with the exterior as a function of this first determined difference, and

- to decide to trigger, or not to trigger, in the system at least one alert according to this determined state.

Thanks to the knowledge of this state representative of the gas exchanges with the outside of the battery, we know if it is normal or abnormal, and therefore we can now alert the users of the system in the event of detection of an abnormal state.

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

- its processor and its memory can be arranged to carry out the operations consisting in determining the state according to a first comparison between the first difference and a predefined critical internal pressure;

- its processor and its memory can be arranged to carry out the operations consisting, in the presence of a first difference lower than the predefined critical internal pressure, higher than a second authorized pressure difference, and lower than a third predefined and higher pressure difference at this second authorized pressure difference, to trigger in the system a first alert requiring a battery check soon;

- its processor and its memory can be arranged to carry out the operations consisting, in the presence of a first difference lower than the predefined critical internal pressure and higher than a third predefined pressure difference, in triggering in the system a second alert requiring verification battery as soon as possible in order to work on the pressure relief valve;

- its processor and its memory can be arranged to carry out the operations consisting, in the presence of a first difference greater than the predefined critical internal pressure, in triggering in the system a third alert requiring an emergency check of the battery due to a problem of overpressure in the latter;

- as a variant, its processor and its memory can be arranged to carry out the operations consisting, in the event of determination of a first difference greater than the predefined critical internal pressure, in analyzing a temporal evolution of the first difference, and in triggering in the system a third alert, requiring an emergency check of the battery due to an overpressure problem in the latter, when the first difference becomes zero for a time interval which is less than a predefined threshold;

- its processor and its memory can be arranged to carry out the operations consisting, in the event of a decision to trigger an alert, of requiring the system to degrade the performance of the battery.

The invention also proposes a system comprising, on the one hand, at least one battery having a variable internal pressure, surrounded by air having a so-called external and variable pressure, and comprising an overpressure valve responsible for balancing the internal pressures and external, and, on the other hand, a control device of the type presented above.

For example, such a system can constitute a vehicle, possibly of the automobile type.

The invention also proposes a control method intended to allow the control of a battery equipping a system, having a variable internal pressure, surrounded by air having a so-called external and variable pressure, and comprising a pressure relief valve charged with balance internal and external pressures.

This control process is characterized by the fact that it includes a step in which:

- a first difference between the internal and external pressures is determined, then

- a state of the battery representative of its gas exchanges with the outside is determined as a function of the first difference determined, and

- One generates, or one does not generate, in the system at least one alert according to this determined state.

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 control method of the type of that presented above for controlling a state of a battery of a system, representative of its gas exchanges with the exterior.

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:

schematically and functionally illustrates a system comprising an example of a battery and a management unit comprising a control device according to the invention,

schematically and functionally illustrates an embodiment of a control device according to the invention, and

schematically illustrates an example of an algorithm implementing a control method according to the invention.

Detailed description of the invention

The object of the invention is in particular to propose a control device DC, and an associated control method, intended to allow the control of the state of a battery BR equipping a system S, representative of its gas exchanges with the outside.

In what follows, it is considered, by way of non-limiting example, that the battery BR is intended to equip a system S constituting a vehicle, possibly of the automobile type (such as for example a car). But the invention is not limited to this application. Indeed, the BR battery can equip any system, and in particular vehicles (land, sea (or river) and air), buildings, installations (including industrial), and electrical (or electronic) devices.

Furthermore, it is considered in what follows, by way of non-limiting example, that the battery BR is intended to supply electrical energy to at least one powertrain (or GMP) of the vehicle S, of the all-electric or rechargeable hybrid type ( that is to say comprising at least one thermal driving machine and at least one electric driving machine). But the battery BR could be intended to supply electrical energy to other electrical (or electronic) equipment or components of the vehicle S.

Schematically represented on the an example of a system S (here a vehicle) comprising a battery BR and a management box BG comprising a control device DC according to the invention.

As illustrated, the battery BR comprises a liquid-tight casing BB (in normal operation) and an assembly EM ensuring the storage of electrical energy for the supply of electrical (or electronic) equipment (or components) of the system S. For example, this assembly EM may include at least one electrical energy storage module, rechargeable and comprising at least one electrochemical electrical energy storage cell. Each cell can, for example, be of the lithium-ion (or Li-ion) or Ni-Mh or Ni-Cd type.

The housing BB defines an enclosure housing the assembly EM and in which there is a variable internal pressure pi. Furthermore, this box BB includes an overpressure valve (or “venting”) VS responsible for balancing the internal pressure pi with the external pressure pe (externally prevailing). This pressure relief valve VS comprises, for example, a membrane allowing only air molecules to pass in both directions to ensure this pressure balance between the inside and the outside of the BB box, and being able to rupture (or burst ) when the internal pressure becomes greater than a predefined threshold sp in order to allow emergency degassing.

The BG management unit is responsible for managing, monitoring and controlling the BR battery, in particular so as to vary its performance if necessary (and in particular when it must operate in degraded mode in certain emergency situations). This is, for example, what those skilled in the art sometimes call a BMS (“Battery Management System”). This management box BG is associated with a first sensor C1 responsible for measuring the internal pressure pi inside the box BB.

Note that the system S also includes a second sensor C2 responsible for measuring the external pressure pe outside the housing BB (not necessarily right next to the battery BR). This external pressure pe and the internal pressure pi can be communicated to a computer on board the system S, and forming part of or constituting an on-board computer OB, for example.

It will also be noted that in the example illustrated without limitation on the , the DC control device is part of the BG management box. But in a variant embodiment (not shown) the control device DC could be external to the management box BG, while being coupled to the latter (BG). Thus, it could, for example, be part of the aforementioned on-board computer OB.

The control device DC is responsible for controlling the state of the battery BR, representative of its gas exchanges with the outside, and comprises for this purpose, as illustrated without limitation in the , at least one processor PR and at least one memory MD arranged to perform operations.

Therefore, the DC control device is made in the form of a combination of electrical or electronic circuits or components (or “hardware”) and software modules (or “software”). But in a variant embodiment not shown, the DC control device could be part of a computer ensuring at least one other function within the system (here the vehicle V).

The processor PR can, for example, be a digital signal processor (or DSP (“Digital Signal Processor”)). This processor PR 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. Thus, it can, for example, be a microcontroller.

The memory MD is live in order to store instructions for the implementation by the processor PR of at least part of the control method described below (and therefore of its functionalities).

The aforementioned operations consist first of all in determining a first difference d1 between the internal pressure pi (measured by the first sensor C1) and the external pressure pe (measured by the second sensor C2), i.e. d1 = pi – pe. The aforementioned operations also consist in determining a state of the battery BR representative of its gas exchanges with the outside, as a function of this first difference d1 determined, and in deciding to trigger, or not to trigger, in the system S at least an alert as a function of this determined state.

It will be understood that this state being representative of the gas exchanges with the outside of the battery BR, it can make it possible to know whether the membrane of the safety valve VS is clogged or not clogged and whether the battery BR is sealed or not sealed ( for example due to the bursting of the membrane). Consequently, when we know that this state is abnormal, we can alert the users of the system S.

For example, the processor PR and memory MD can be arranged to perform the operations consisting in determining the state according to a first comparison between the first difference d1 and a predefined critical internal pressure pc. This critical internal pressure pc can be a constant value which is chosen slightly lower than the burst pressure of the pressure relief valve diaphragm VS.

It will be understood that if the first difference d1 is greater than the critical internal pressure pc, this means that the membrane of the overpressure valve VS is completely clogged and about to burst, which will then induce a loss of tightness of the BR battery, potentially (very) dangerous.

In the presence of this option, the processor PR and memory MD can be arranged to additionally perform the operations consisting, when the first difference d1 is lower than the predefined critical internal pressure pc, higher than a second authorized pressure difference d2 and lower than a third pressure difference d3 (predefined and greater than this second authorized pressure difference d2), or when d2<d1<d3<pc, to trigger in the system S a first alert which soon requires a verification of the battery BR.

For example, the second allowed pressure difference d2 is a difference between the internal pressure pi and the external pressure pe which is allowed during the time which is necessary to equalize the pressure in the battery BR. It is defined by the manufacturer of the VS overpressure valve. Also for example, the third pressure difference d3 is a difference between the internal pi and external pressure pe which is used to differentiate a first alert from a second alert.

It will be understood that when the inequality d2 < d1 < d3 < pc is verified, this means that the battery BR is tight, but that its pressure relief valve VS is possibly being clogged. Battery BR is therefore in a state (d2 < d1 < d3 < pc) in which its gas exchanges with the exterior are not completely normal while being liquid-tight. The purpose of the first alert is therefore to report a small anomaly which requires the battery BR to be examined relatively quickly in an after-sales service, in order, in particular, to check the level of clogging of the pressure relief valve VS.

Also in the presence of the aforementioned option, the processor PR and memory MD can also be arranged to additionally perform the operations consisting, when the first difference d1 is lower than the predefined critical internal pressure pc and higher than the third predefined pressure difference d3 , ie when d2<d3<d1<pc, to trigger in the system S a second alert which requires checking as soon as possible of the battery BR in order to intervene on the pressure relief valve VS.

It will be understood that when the inequality d2 < d3 < d1 < pc is verified, this means that the battery BR is tight, but that its overpressure valve VS is faulty, for example because it is partially clogged. This is the reason why the first difference d1 approaches the critical internal pressure pc. Battery BR is therefore in a state (d2 < d3 < d1 < pc) in which its gas exchanges with the outside are very reduced while still being liquid-tight. The purpose of the second alert is therefore to report a serious anomaly which requires the battery BR to be examined quickly (as soon as possible) in an after-sales service, in order, in particular, to clean or replace the pressure relief valve VS which is at least partially clogged. . A clogging in fact induces a reduction in the capacity of the battery BR to exchange gases with the outside via its pressure relief valve VS, which is potentially dangerous.

Also in the presence of the aforementioned option, the processor PR and memory MD can also be arranged to additionally perform the operations consisting, when the first difference d1 is greater than the predefined critical internal pressure pc, or when d1 > pc, in triggering in the system S a third alert requiring an emergency check of the BR battery due to an overpressure problem in the latter (BR).

It will be understood that when the inequality d1 > pc is verified, this means that the battery BR is still tight, but that the membrane of its pressure relief valve VS is about to burst. The BR battery is therefore in a state (d1 > pc) in which its gas exchanges with the outside are non-existent while still being liquid-tight. The purpose of the third alert is therefore to report a very serious problem which requires urgent examination of the BR battery in an after-sales service, in order to clean or replace the totally clogged VS pressure relief valve. A total clogging in fact induces a total inability of the battery BR to exchange gases with the outside via its pressure relief valve VS, which is dangerous.

In a variant, the processor PR and memory MD can be arranged to perform the operations consisting, when the first difference d1 is greater than the predefined critical internal pressure pc, or when d1 > pc, in analyzing the temporal evolution of the first difference d1 , and triggering in the system S the third alert when the first difference d1 becomes zero for a time interval which is less than a predefined threshold sp. This predefined threshold sp is strictly less than the time required for pressure equalization in normal operation of the pressure relief valve VS and which is known to the manufacturer of the latter (VS). In this variant, we do not trigger the third alarm when we detect that d1 becomes greater than pc, but we wait to see the temporal evolution of d1 before making a decision (if d1 very quickly becomes zero again (faster than when balancing), the membrane has burst and therefore the third alarm is triggered).

It will indeed be understood that just before the membrane bursts, we are in the situation d1 > pc, and when the bursting occurs, gas begins to leave the box BB until the internal pressures pi and external pressures pe are equalized (i.e. d1 = 0), which takes a time at most equal to the predefined threshold sp which is known to the manufacturer of the pressure relief valve VS. The BR battery is then no longer liquid-tight, and therefore an ingress of liquid could induce a short-circuit likely to trigger a thermal runaway resulting in overheating or even a fire. The detection of the condition d1 > pc followed by the detection of the fact that d1 has become zero after a time interval less than or equal to the predefined threshold, therefore makes it possible to detect that the battery BR is no longer tight. The BR battery is therefore in a state (d1 = 0 after bursting) in which it is no longer liquid-tight due to the bursting of its membrane.

It will also be noted that the processor PR and memory MD can also be arranged to carry out the operations consisting, in the event of a decision to trigger an alert, of requesting from the system S a deterioration in the performance of the battery BR. This performance degradation may possibly be variable depending on the seriousness of the situation. Thus, it can be envisaged that in the event of a third alert the degradation is greater than in the event of a second alert, and that in the event of a second alert the degradation is greater than in the event of a first alert. Thus, in the case of a third alert, the degradation may possibly be total (which results in the de-energization of the BR battery). But we can also consider that the degradation is the same regardless of the determined alert (first, second or third).

It is also possible to envisage memorizing (or storing) an identifier representative of the alert, for example in an incident log of the system S or else in the management box BG or even in the control device DC. This may also allow the last stored alert message to be redisplayed and/or rebroadcast in the S system when the S system is used again.

For example, the first alert can be done by displaying a first dedicated service indicator (for example the BR battery indicator), possibly in an orange color, or a first dedicated textual alert message on a screen of the system S, such as for example (here) that of the dashboard or that of the central instrument panel, and/or by broadcasting a first dedicated sound (or audio) alert message via at least one loudspeaker present in the system S. In the case of a system S constituting a vehicle, the display of the first alert may continue until the end of the vehicle rolling phase.

Also for example, the second alert can be done by displaying a first dedicated service indicator (for example the BR battery indicator), possibly in a red color, or a second dedicated textual alert message on a screen of the system S, such as for example (here) that of the dashboard or that of the central instrument panel, and/or by broadcasting a second dedicated sound (or audio) alert message via at least one loudspeaker present in the system S. In the case of a system S constituting a vehicle, the display of the second alert continues until the end of the rolling phase of the vehicle.

Also for example, the third alert can be done by displaying a first dedicated service warning light (for example the BR battery warning light), possibly in a red color, and/or a second dedicated service warning light (for example example the immediate stop (or "stop") warning light, possibly in red, or a third dedicated textual alert message on an S system screen, such as for example (here) that of the dashboard or that of the central handset, and/or by broadcasting a third dedicated sound (or audio) alarm message via at least one loudspeaker present in the system S. In the case of a system S constituting a vehicle, the display of the third alert continues until the end of the vehicle driving phase.

It will also be noted that in the example illustrated without limitation on the , the control device DC comprises a computer CD comprising the processor PR and the memory MD. But the processor PR and the memory MD could be part of a computer that is not part of the control device DC, and in particular of a computer of the management box BG (or of the on-board computer OB).

It will also be noted, as illustrated without limitation in the , that the computer CD (and therefore here the control device DC) can also comprise, in addition to the random access memory MD and processor PR, a mass memory MM, in particular for storing the internal pressures pi and external pressures pe as well as possibly an identifier of the last alert message triggered, and intermediate data involved in all its calculations and processing. Furthermore, this computer CD (and therefore here the control device DC) can also comprise an input interface IE for receiving at least the internal pressures pi and external pressures pe, to use them in calculations or processing, possibly after having formatted and/or demodulated and/or amplified them, in a manner known per se, by means of a digital signal processor PR′. In addition, this computer CD (and therefore here the control device DC) can also comprise an output interface IS, in particular for delivering the instructions for triggering the various alerts or messages containing these alerts.

The invention can also be considered in the form of a control method, intended to be implemented for the battery BR of the system S (here a vehicle).

A control method according to the invention comprises a step 10-80 in which one (the control device DC) begins by determining the first difference d1 between the internal pressures pi and external pressure pe, then one (the control device DC) determines a state of the battery BR representative of its gas exchanges with the outside, as a function of this first determined difference d1, and at least one alert is generated or not generated in the system S as a function of this determined state .

We have schematically illustrated on the an example of an algorithm implementing a control method according to the invention. This algorithm starts as soon as you start using the BR battery.

In a sub-step 10 one (the control device DC) can initialize all the parameters involved in the control process and one (the control device DC) can trigger the redisplay and/or the rebroadcast in the system S of the last message alert stored.

Then, in a sub-step 20, one (the control device DC) determines the first difference d1 between the internal pressure pi and the external pressure pe, ie d1=pi-pe.

Then, in a sub-step 30, one (the control device DC) determines if the first difference d1 is greater than the predefined critical internal pressure pc, ie if d1>pc.

If so (d1>pc), in a sub-step 40 one (the control device DC) triggers a third alert in the system S, memorizes (or stores) an identifier representative of this third alert, and requests from the system S a third BR battery performance degradation.

If not (d1<pc), in a sub-step 50 one (the control device DC) determines if the first difference d1 is greater than the third predefined pressure difference d3, ie if d1>d3.

If so (d1>d3), in a sub-step 60 one (the control device DC) triggers a second alert in the system S, memorizes (or stores) an identifier representative of this second alert, and requests from the system S a second BR battery performance degradation.

If not (d1<d3), in a sub-step 70 one (the control device DC) determines if the first difference d1 is greater than the second authorized pressure difference d2, ie if d1>d2.

If so (d1>d2), in a sub-step 80 (the control device DC) triggers a first alert in the system S, memorizes (or stores) an identifier representative of this first alert, and requests from the system S a first performance degradation of the BR battery.

In the negative (d1 <d2), one (the control device DC) performs sub-step 20 again because there is no apparent problem of reduction of gas exchanges with the exterior of the battery BR.

Sub-steps 10 to 80 are part of an example implementation of step 10-80 of the control method.

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 PR, is able to implement the control method described above to control a state of the battery BR representative of its gas exchanges with the outside.

Claims (10)

Control device (DC) for controlling a battery (BR) equipping a system (S), having a variable internal pressure, surrounded by air having a so-called external and variable pressure, and comprising an overpressure valve (VS) charged with balancing said internal and external pressures, characterized in that it comprises at least one processor (PR) and at least one memory (MD) arranged to perform the operations consisting in determining a first difference between said internal and external pressures, in determining a state of said battery (BR) representative of its gas exchanges with the outside, as a function of said first determined difference, and to decide to trigger, or not to trigger, in said system (S) at least one alert as a function said determined state. Device according to Claim 1, characterized in that the said processor (PR) and memory (MD) are arranged to carry out the operations consisting in determining the said state according to a first comparison between the said first difference and a predefined critical internal pressure. Device according to Claim 2, characterized in that the said processor (PR) and memory (MD) are arranged to carry out the operations consisting, in the presence of a first difference lower than the said predefined critical internal pressure, higher than a second pressure difference authorized, and lower than a third predefined pressure difference and higher than said second authorized pressure difference, to trigger in said system (S) a first alert shortly requiring a check of said battery (BR). Device according to Claim 2, characterized in that the said processor (PR) and memory (MD) are arranged to carry out the operations consisting, in the presence of a first difference lower than the said predefined critical internal pressure and higher than a third pressure difference predefined, to trigger in said system (S) a second alert requiring verification as soon as possible of said battery (BR) in order to intervene on said pressure relief valve (VS). Device according to Claim 2, characterized in that the said processor (PR) and memory (MD) are arranged to carry out the operations consisting, in the presence of a first difference greater than the said predefined critical internal pressure, in triggering in the said system (S ) a third alert requiring an emergency check of said battery (BR) due to an overpressure problem in the latter (BR). Device according to Claim 2, characterized in that the said processor (PR) and memory (MD) are arranged to carry out the operations consisting, in the event of determination of a first difference greater than the said predefined critical internal pressure, in analyzing a temporal evolution of said first difference, and triggering in said system (S) a third alert, requiring an emergency check of said battery (BR) due to an overpressure problem in the latter (BR), when said first difference becomes zero for a time interval less than a predefined threshold. Device according to one of Claims 1 to 6, characterized in that the said processor (PR) and memory (MD) are arranged to carry out the operations consisting, in the event of a decision to trigger an alert, in requesting from the said system (S) a performance degradation of said battery (BR). System comprising at least one battery (BR) having a variable internal pressure, surrounded by air having a so-called external and variable pressure, and comprising an overpressure valve (VS) responsible for balancing said internal and external pressures, characterized in that that it further comprises a control device (DC) according to one of the preceding claims. Method for controlling a battery (BR) equipping a system (S), having a variable internal pressure, surrounded by air having a so-called external and variable pressure, and comprising an overpressure valve (VS) responsible for balancing said internal and external pressures, characterized in that it comprises a step (10-80) in which a first difference is determined between said internal and external pressures, then a state of said battery (BR) representative of its gas exchanges is determined with the exterior, as a function of said first determined difference, and generating, or not generating, in said system (S) at least one alert as a function of said determined state. Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the control method according to claim 9 for controlling a state of a battery (BR) d a system (S), representative of its gas exchanges with the exterior.