Method for warning of a state of an electric traction battery

Abstract

Method for warning of a state of an electric traction battery (B) of a vehicle, this battery (B) comprising: - a control device (BMS) of the traction battery (B), comprising the means of acquisition, processing by software instructions stored in a memory as well as the control means required for implementing the method, and - an electromechanical switch comprising an open position and a closed position controlled by the control device (BMS), this control device (BMS) of the traction battery (B) being configured to detect the state of the battery (B) and acquire information of occurrence of an impact against the vehicle, and if the information of occurrence of the impact is acquired, this method executes a step of successive commands of the switch from its open position to its closed position so that the closed positions follow a predetermined and repeated sequence dependent on the detected state. Figure 2.

Description

Title of the invention: Method for warning of a state of an electric traction battery

[0001] Motor vehicles comprising an electric drive machine mechanically coupled to a set of wheels or to a wheel also comprise a so-called traction battery, supplying electrical power to the electric drive machine, whether the latter is a traction or propulsion machine.

[0002] These traction batteries have a much greater electrical energy storage capacity than conventional lead batteries known as service batteries, and comprise a multitude of electrochemical cells generally connected in series to each other in blocks, each block being a module of the traction battery.

[0003] It is known that, under certain conditions of use and wear of these cells, one of them rises in temperature by exothermic chemical reaction and causes the start of a fire which then spreads to neighboring cells and thus creates what those skilled in the art call thermal runaway.

[0004] One of the critical usage conditions is when the vehicle suffers a severe accident, i.e. at high speed: the structural deformations are such that sometimes this can create or accelerate a thermal runaway of the traction battery by the appearance of an internal or external short circuit in the traction battery.

[0005] A traction battery control device is generally known which is capable of detecting such thermal runaway and signaling it by a signaling means integrated into the vehicle dashboard.

[0006] Unfortunately, this signaling means may be out of use after such an accident, so that even if the thermal runaway is detected and reported by the traction battery control device, it is not certain that either the occupants or the occupant rescue intervention personnel can be warned of this start of thermal runaway. This is detrimental because this thermal runaway information may lead to a change in a decision by the occupant rescue intervention personnel, as well as alerting the occupants that, despite the state of shock, they must not remain in the passenger compartment of the vehicle.

[0007] The aim of the invention is to remedy this problem.

[0008] To this end, the invention relates to a method for warning of a state of an electric traction battery of a vehicle, this battery comprising: - a traction battery control device, comprising the means of acquisition, processing by software instructions stored in a memory as well as the control means required for implementing the method, and - an electromechanical switch comprising an open position and a closed position controlled by the control device, this traction battery control device being configured to detect the state of the battery and acquire information on the occurrence of an impact against the vehicle, and if the information on the occurrence of the impact is acquired, this method executes a step of successive commands of the switch from its open position to its closed position so that the closed positions follow a predetermined and repeated sequence dependent on the detected state.

[0009] Indeed, the traction battery and its control device are among the best protected elements of the vehicle in the event of an impact. The probability that the control device will be operational after this impact is high while the signaling means is more likely out of service. The electromechanical switch is also protected against this impact, and has a disadvantage which is here transformed into an advantage by this invention: when it is controlled, whether it goes from an open state to a closed state or vice versa, it makes noise. Now this noise is audible from outside the vehicle, sometimes amplified by the resonance box of a hermetic casing forming an outer envelope of the traction battery. The control of this electromechanical switch, after the impact, then makes it possible to send a signal to the emergency personnel even if the signaling means is out of service.The sequence used by the method is then significant of the state of the traction battery detected or determined by the control device, in particular if this state is a determined or predictable start of thermal runaway.

[0010] Thus, for example, and according to one embodiment of the invention, the detected state is a state of thermal runaway of the traction battery.

[0011] According to one embodiment of the invention, this predetermined sequence is that of a Morse code call for help message.

[0012] According to an alternative embodiment of the invention, this predetermined sequence has identical closed position times at a frequency of more than 100 commands per minute.

[0013] According to one embodiment of the invention, the detected state is a state of non-thermal runaway of the traction battery.

[0014] It should be noted here the considerable advantage that this brings to the intervention personnel: This information is of great use because the intervention personnel have, apart from this invention, no possibility of knowing if the control device is still operational and is capable of detecting or determining the thermal runaway. In doubt, the intervention personnel can rush their actions to the detriment of the occupants while there is, from the point of view of the battery, no emergency. Our invention makes it possible, from this point of view, to reassure the intervention personnel: they perceive the audible and reassuring signal from the electromechanical switch indicating to them that the traction battery is under control and that there is no risk of thermal runaway, and therefore no urgency to evacuate the occupants in view of this risk of thermal runaway.

[0015] Thus and according to one embodiment of the invention, this predetermined sequence has identical closed position times at a frequency of less than 100 commands per minute.

[0016] More precisely, this predetermined sequence has identical closed position times at a frequency of between 40 and 80 commands per minute, in particular 60 commands per minute.

[0017] It will be noted that these frequencies are not chosen at random, but correspond to a universal signal known to all: the heartbeat frequency. Thus an accelerated heartbeat, in particular above 100, intuitively induces the idea of ​​danger, whereas below 100, intuitively induces the idea of ​​a normal situation... of the traction battery. The ultimate danger can be signified by a frequency of 180 to 210 for example whereas a normal situation corresponds for example to a frequency around 60, or between 40 and 80. The invention describes here frequency intervals, it is clear that this invention also covers the case of a continuously variable frequency, for example ranging from 60 to 210, this variation being a function of the variation of the state of the battery, for example a function of its increase in temperature.

[0018] The invention also relates to a motor vehicle comprising an electric traction battery, this traction battery comprising: - a traction battery control device, comprising the means of acquisition, processing by software instructions stored in a memory as well as the control means required for implementing a method as previously described, and - an electromechanical switch comprising an open position and a closed position controlled by the control device according to this method.

[0019] According to one embodiment of the invention, this vehicle comprises an electrical component powered by the traction battery, this traction battery comprising a means for electrically isolating the traction battery from this component, this isolation means comprising redundant cut-off means controlled by the traction battery control device, the electromechanical switch being one of these redundant cut-off means.

[0020] Indeed, it is advantageous that the actuation of the electromechanical switch does not in itself cause the appearance of a short circuit, in particular if the electrical component itself is short-circuited. Also, when the traction battery is isolated by means of isolation, the fact that the electromechanical switch is redundant allows, even if it is activated, to keep the traction battery isolated from the electrical component. This redundancy is pre-existing on these vehicles, as will be detailed later.

[0021] According to one embodiment of the invention, this vehicle comprises an electrical power supply system for the control device, this power supply system comprising a second electric battery for powering the control device.

[0022] According to one embodiment of the invention, this vehicle comprises an electrical power supply system for the control device, this power supply system comprising a second direct-direct current converter electrically coupled to the traction battery and solely dedicated to powering the control device of the traction battery.

[0023] According to one embodiment of the invention, this electrical power supply system of the control device is entirely housed inside a hermetic casing of the traction battery, this casing also housing the cells and / or the modules of the traction battery.

[0024] According to one embodiment of the invention, this second converter is directly connected to the cells of the battery, by short-circuiting the isolation device.

[0025] These characteristics make it possible to secure the operability of the control device and the electromechanical switch. For example, this second electric battery is housed inside the sealed casing of the traction battery, or in a location very sheltered from impacts of the vehicle. The objective is to ensure that the noise, and therefore the audible sequence emitted by the electromechanical switch is operational even after a high-speed vehicle accident.

[0026] Thus the invention also relates to a traction battery as previously described, the electrical power supply system of the control device being entirely housed inside a hermetic casing of the traction battery, this casing furthermore housing the cells and / or the modules of the traction battery and the control device of the traction battery.

[0027] For example, in a situation where the traction battery is not yet mounted in the vehicle, during delivery of the traction battery to the vehicle assembly plant for example, this traction battery control device will be configured to detect this situation, for example by detecting the non-connection of the traction battery to the electrical component, and thus autonomously to detect the state of the battery and the situation of the battery not mounted, and if the traction battery is not mounted, this control device executes a step of successive commands of the switch from its open position to its closed position so that the positions closed follow a predetermined and repeated sequence dependent on the detected state.

[0028] Other features and advantages will appear on reading the following description of a particular, non-limiting embodiment of the invention, given with reference to Figures 1 to 3 in which:

[0029] [Fig.l]: represents an internal diagram of an electric traction battery for which the method according to the invention applies.

[0030] [Fig.2]: represents a partial diagram of the vehicle's electric traction battery according to the invention, as well as the electrical power supply system of the control device according to the invention.

[0031] [Fig.3]: represents a control sequence of an electromechanical switch according to the method of the invention.

[0032] In the following, reference is made to Figures 1 and 2 taken in combination. When reference is made to one or more specific figures, these figures are to be taken in combination with the other figures for the recognition of the designated numerical references.

[0033] These figures 1 and 2 therefore disclose an example of an internal diagram, for [Fig.l], of an electric traction battery B for which the method according to the invention applies, as well as a more general diagram, for [Fig.2], integrating in particular an electrical power supply system CV2, BS2 of a traction battery control device BMS according to the invention.

[0034] This traction battery B comprises, as is known to those skilled in the art, electrochemical cells CL grouped into MO modules, these MO modules being connected together in series and / or in parallel and delivering to the terminals of this battery a direct voltage between 300 and 1000V, in particular 450V or 800V to supply what will be called a high voltage network, that is to say working at the potential of the electric traction battery B, therefore between 300 and 800V.

[0035] This high voltage network can be coupled to a low voltage network via a CV voltage converter. This low voltage network is also called the on-board network, present in the vehicle, and is powered by a service battery BS of lower voltage than the traction battery B, for example a direct voltage between 10 and 30V, in particular 12V, this service battery BS being in particular recharged by the CV voltage converter. It will be noted that in [Fig.2], the high voltage network is represented by a double continuous line, while the low voltage network is represented by a dotted line.

[0036] The traction battery B supplies an electrical component, for example an electric motor M of the vehicle, via the high-voltage network. This electric motor M is for example mechanically coupled to a set of wheels of the vehicle, and may be reversible, i.e. include a mode of recharging the battery of traction B, for example a regenerative braking mode known to those skilled in the art.

[0037] Thus the high voltage network comprises a positive main branch coming out of a positive terminal of the traction battery B while being connected to the positive pole of the electric machine M, and a negative main branch coming out of a negative terminal of the traction battery B while being connected to the negative pole of the electric machine M.

[0038] The high voltage network can also connect to the traction battery B a charger C of the traction battery B, this charger C being intended to be electrically connected to a charging terminal external to the vehicle, in particular a charging terminal of a terrestrial electrical network, this is then referred to as an on-board charger C.

[0039] The traction battery B can therefore supply the on-board network via the direct current to direct current CV converter.

[0040] The on-board network connects to the service battery BS, for example, equipment or consumer elements such as computers, including that of an electronic control or supervisor unit of the vehicle, known by the English acronym "ECU" (not shown) and which is on board the motor vehicle to command or control various control members or other computers.

[0041] The electronic control unit can act as a supervisor of the vehicle, managing in particular exchanges of information via a CAN communication network with other computers, sensors, subsystems of the vehicle. One of these other computers is in particular a device for controlling the traction battery BMS that the traction battery B comprises. This sign BMS is also an English acronym designating a “Battery Management System” referenced in [Fig.2] only.

[0042] The electronic control unit or supervisor of the vehicle, controls, commands and supervises the computers of the previously mentioned CAN network.

[0043] This high voltage network can supply other electrical components, such as auxiliary elements: an air conditioning or heating system, an air compressor, etc.

[0044] The traction battery B comprises an isolation means DI shown in [Fig.2], suitable for cutting off the power supply from the high voltage network, and in particular the power supply to the electrical machine M, to the converter CV, to all the electrical components electrically connected to the traction battery B via the high voltage network. This isolation means DI may comprise branches connecting the traction battery B to the charger C, where appropriate to the converter CV.

[0045] In [Fig. 1], which is not limiting, the isolation means DI comprises cut-off means, in particular five switches controllable by the device of control of the traction battery BMS, including at least one electromechanical switch, as well as fuses and / or pyrotechnic cut-off means. The switches are referenced K1 to K5, advantageously one switch for each branch of the high-voltage network. [Fig.l] discloses two main switches K2, K3. A main switch K2 is located on the so-called positive branch of the isolation device DI connecting the positive pole of the traction battery B to a positive pole of the electric machine M. A main switch K3 is located on the so-called negative branch of the isolation device DI connecting the negative pole of the traction battery B to a negative pole of the electric machine M.

[0046] The isolation device also comprises two fuses F2 and F3 on a branch branching off the positive branch of the isolation means DI leading respectively to the charger C and to the converter CV. The traction battery B houses a fuse F1 between two modules MO or two electrochemical cells CL. A branch branching off a portion of the positive branch comprising the main switch K2 comprises a switch K1 and a resistor R in series.

[0047] It will be noted that the electromechanical switch according to the invention can also be a switch triggering a pyrotechnic fuse, for example one of the fuses F2 or F3.

[0048] Voltages U1 to U6 for the positive branches of the isolation device DI, connected directly or indirectly to the positive pole of the traction battery B and voltages U00, U01, U02 for the negative branches of the isolation means DI, connected directly or indirectly to the negative pole of the traction battery B, are indicated in [Fig.l] at specific points of the isolation means DI. For example, when K1, K2, K3 are open, the voltage difference U1-U00 is the internal voltage of the traction battery B, and the voltages U6, U02, U4 are the voltages across the traction battery B and are zero if the charger C and the converter CV are not in operation.

[0049] Thus, the switches K1 to K3 make it possible to isolate the traction battery B from any electrical component, so that the cut-off means K4 and K5 are, for example, redundant cut-off means, as are the fuses F2, F3 if they are controlled by the BMS control device of the traction battery B, which is the case, for example, with pyrotechnic fuses. Thus, for example, if the switches K1 to K3 are open, the traction battery B is isolated from the high-voltage network and therefore from the electrical components M, C, CV connected to it, and any action on the switches K4 and K5 will have no effect on this electrical isolation of the traction battery B. Thus, if the switch K4 is an electromechanical switch, it can be controlled by the BMS traction battery control device according to the method of the invention, so as to emit a noise audible from outside the vehicle by a succession of electromechanical switch clicks.

[0050] Also, but less securely, if switch K3 is open, the negative branch of traction battery B is isolated from the electrical components M, C, CV connected to it, thus all the other switches K1, K2, K4, K5 are redundant with respect to switch K3 and could be controlled according to the sequences of the method, but the isolation of traction battery B is not in this case complete since the positive branch of traction battery B could still be connected permanently or alternatively to the electrical components M, C, CV which, as explained previously, is not entirely secure.

[0051] Also, if fuse F3 is a pyrotechnic fuse that has been triggered by the BMS control device, switch K4 is redundant regardless of the state of the other switches, and so on.

[0052] It will be noted that the electromechanical switch according to the invention is not necessarily a means for cutting off the isolation means DI. For example, this electromechanical switch, in a variant not shown, is a switch activating a system supplied with power by the on-board network and controlled by the BMS control device of the traction battery B, this on-board network not being cut off by the isolation means DI but by another isolation means or not cut off at all: for example, a system for evacuating condensation water occurring inside a hermetic casing CH of the traction battery B, or a system for heating the modules of the traction battery B, in particular the electrical resistors deactivated by this other isolation means.

[0053] [Fig.2], as already explained, further discloses an example of the electrical power supply system CV2, BS2 of the traction battery control device BMS according to the invention. This [Fig.2] shows the high-voltage network in a double continuous line, as well as the on-board network in dotted lines. The isolation means DI is represented overall and schematically by a rectangle inside which we will find the electrical switches K1 to K5 and the fuses F2, F3 of [Fig.1] although they are not shown in [Fig.2]. Some electrical components are shown such as the electrical motor machine M, as well as the converter CV. This [Fig.2] has the advantage of illustrating this power supply system which includes: - a second BS2 electric battery to power the BMS control device, and - a second CV2 converter capable of recharging the second BS2 battery from the high voltage network.

[0054] It will be noted that the traction battery B comprises the hermetic casing CH, this hermetic casing CH containing the cells CL, modules MO, the isolation device DI, the control device BMS, as well as at least part of the power supply system. CV2, BS2 electrical system of the BMS traction battery control device, which has the advantage of keeping all the safety functions of the traction battery B under the protection of the CH hermetic casing, but this is not mandatory because for example the CV2, BS2 electrical power supply system could be external to the CH hermetic casing, or even the BMS control device.

[0055] It is also noted that the electrical power supply system CV2, BS2 can also comprise the service battery BS associated with the converter CV: thus the second battery BS2 and the second converter CV2 are redundant with respect to the service battery BS and the converter CV, which secures the electrical power supply of the BMS control device. This BMS control device has, for example and as illustrated, two separate inputs for its electrical power supply coming from the low-voltage network. This electrical power supply system CV2, BS2 can also comprise a battery internal to the BMS control device, this list of examples not being exhaustive.

[0056] The second electric battery BS2 and the second converter CV2 have the advantage of being independent of the converter CV and the service battery BS. Indeed, in the event of an impact or accident to the vehicle, it is not guaranteed that the service battery BS, often housed in a front compartment of the vehicle, is still operational.

[0057] Furthermore, this same electrical power supply system CV2, BS2, and in particular the second battery BS2 can power the electronic control or supervisor unit of the vehicle (not shown in the figures), for the same reasons.

[0058] According to a variant of the invention, not shown, the electrical power supply system of the BMS control device comprises only the second current converter CV2 electrically coupled to the traction battery and solely dedicated to powering the BMS control device of the traction battery. According to this variant, this electrical power supply system is entirely housed inside the hermetic casing CH of the traction battery, this casing also housing the cells CL and / or the modules MO of the traction battery B. This second converter CV2 is directly connected to the cells CL of the battery B, by short-circuiting the isolation device DI.Thus the electrical power supply system of the BMS control device is entirely housed inside the hermetic casing CH of the traction battery B, this casing also housing the cells and / or the modules of the traction battery and the BMS control device of the traction battery. For example, in a situation where the traction battery B is not yet mounted in the vehicle, during the delivery of the traction battery B to the vehicle assembly plant for example, this BMS control device of the traction battery will be configured to detect this situation, for example by detecting the non-connection. from the traction battery B to the electrical component M, and thus autonomously to detect the state of the battery and the situation of the unmounted battery, and if the traction battery is unmounted, this BMS control device executes a step of successive commands of the switch K4, K5 from its open position to its closed position so that the closed positions follow a predetermined and repeated sequence dependent on the detected state.

[0059] This vehicle comprises means for detecting shocks or accidents, for example acceleration sensors housed at different locations on the bodywork, the electronic control unit being configured to receive information from these sensors, and process them to deduce the occurrence of a shock or accident, which is perfectly known to those skilled in the art.

[0060] It is also known, in the event of detection of such an impact, that the electronic control unit triggers means for protecting the occupants of the vehicle, in particular well-known means such as pyrotechnic air bags commonly known as "air bags" or seat belt pretensioners. This same electronic control unit communicates this impact information to the BMS control device via the CAN network, and depending on this impact information the BMS control device will control the isolation means DI while monitoring the state of the traction battery B.

[0061] It will also be noted that, as a variant, the impact detection and the control of the occupant protection means can be carried out by a third dedicated computer called an airbag computer (not shown).

[0062] Such a BMS control device is known to those skilled in the art for, in addition to determining a state of charge or health of the traction battery B, and in association with temperature, voltage, and / or pressure sensors internal to the traction battery B, determining a thermal runaway state initiated by at least one CL cell of the traction battery B. This information on the thermal runaway state is communicated via the CAN network to the electronic control unit.

[0063] This determination of the thermal runaway state is regulatory. It allows, in the event of a fire starting in the traction battery B, to inform the driver, by a display on a dashboard, associated with an audible alert on the dashboard "High battery temperature: Stop as soon as possible and leave the vehicle". The challenge is to inform the driver while giving him enough time (at least 5 minutes) to stop the vehicle if possible in an open area, and to allow him to evacuate the occupants calmly, before the fire comes out of the battery (if this were to happen).

[0064] This determination of the thermal runaway state, and by transposition the non-thermal runaway state, is carried out to protect the occupants, in particular against an internal short circuit in a CL cell, which would set fire to this CL cell, a fire which would spread to several neighboring cells, thus with an “exponential” runaway phenomenon. This determination pales in comparison to production defects in the CL cells (impurity on the separator) or excessive lithium deposits (Li-plating) which would pierce the separator of a single cell.

[0065] The principle of determining a thermal runaway is to recognize signatures of the start of fire on a (first) CL cell. Several solutions exist, one can place a pressure sensor which notes a rapid increase in pressure, one can also detect an abnormal voltage drop, an increase in cell temperature, a loss of insulation. The alert being restrictive and potentially worrying, one must be sure to do it wisely. For this one generally uses a combination of these principles, these methods being well known to those skilled in the art.

[0066] Another important life situation is a vehicle accident, also called a crash. The vehicle is designed so that the traction battery B is not damaged in all crashes defined by the regulations, and for crashes resulting from tests defined by organizations such as EURO Ncap. In all these crash cases, the manufacturer can guarantee that the battery will not catch fire, no cell damage, no short circuit on busbars for example. However, for very high speed crashes where emergency services will intervene to extricate the vehicle's occupants, these first responders need to know the seriousness of the situation in the traction battery, in order to adopt an appropriate extrication:

[0067] If the traction battery B can inform of its safe state, the extrication can be done slowly, to limit additional injuries that could potentially be caused by the extrication itself.

[0068] Conversely, if traction battery B can indicate a risk of a fire starting in the future, then this information is very useful and makes it possible to prioritize rapid extrication.

[0069] However, in the event of a crash, it is not possible to guarantee that information on the status of the traction battery B can reach the instrument panel. In particular, computers may be damaged. The control unit for the traction battery B, the BMS, is, on the other hand, well protected by the sealed casing CH.

[0070] The electromechanical switch K4, K5 is for example an electromagnetic relay, comprising a magnetic coil controlled and powered by the control device BMS, itself powered by the second battery BS2 for an autonomy of for example a few hours. This coil will magnetically attract a contactor which, when it closes, will “click” and make a first clicking noise while allowing the passage of a power current for example. Then, when this coil is no longer supplied with current, by an elastic means the contactor will return to its open position and when it comes to a stop in the open position will make a second clicking noise. Other variants are possible, for example this contactor can be bistable rather than monostable, each electromechanical switch will have its own noise signature depending on its technology.

[0071] Thus, throughout the text of this document, an electromechanical switch will be understood to mean any switch (or contactor) having an internal mechanical part whose movement is necessary and electrically controlled to change from a closed state to an open state or vice versa, this change of state causing a clicking noise.

[0072] [Fig.3] discloses a method according to the invention.

[0073] Thus the method according to the invention is a method of warning of a state of the electric traction battery B of the vehicle, this battery B comprising: - the BMS control device of the traction battery B, comprising the means of acquisition, processing by software instructions stored in a memory as well as the control means required for implementing the method, and - an electromechanical switch K4, K5 comprising an open position E0 and a closed position El controlled by the BMS control device.

[0074] This BMS control device of the traction battery B is configured to detect the state of the battery B and acquire information on the occurrence of an impact against the vehicle and, if the information on the occurrence of the impact is acquired, this method executes a step of successive commands of the switch K4, K5 from its open position E0 to its closed position E1 so that the closed positions E1 follow a predetermined and repeated sequence dependent on the detected state.

[0075] This detected state is for example one of: - the thermal runaway state of the traction battery, and / or - the non-thermal runaway state of the traction battery.

[0076] In the event of detection, and / or determination of the thermal runaway state of the traction battery B, this predetermined sequence is that of a Morse code call for help message. Alternatively, this predetermined sequence has identical closed position times E1 at a frequency of more than 100 commands per minute.

[0077] In the event of detection, and / or determination of the non-thermal runaway state of the traction battery B, this predetermined sequence has identical closed position times E1 at a frequency of less than 100 commands per minute, in particular between 40 and 80 commands per minute, in particular still 60 commands per minute.

[0078] [Fig.3] in particular illustrates one of the examples of these sequences in the case of detection, and / or determination of the thermal runaway state of the battery of traction B, this predetermined sequence being that of a call for help message in Morse code. This [Fig.3] illustrates a diagram representing the successive closed E El and open EO states according to this Morse sequence, therefore as a function of time t. The points PI represent the closing times of the electromechanical switch K4, K5, that is to say the times when the control device BMS commands the closing of this switch and it is actually closed: these times are the times tb t2, t 3, t4, t5, t6. By symmetry, the points P2 represent the opening times of the electromechanical switch K4, K5, that is to say the times when the control device BMS commands the opening of this switch and it is actually open: these times are the times tu, ti2, tn, tu, ti5, ti6. The first closing time (or duration) is determined by tu - b the second closing time is determined by ti2 - t2 and so on.We note that the first three beats are shorter than the last three beats, this sequence of six beats repeating itself and thus recalling the SOS signal in Morse code.

[0079] For the example described above of the electromechanical switch, namely a monostable switch in the open position, the points PI represent the moment when the noise of the contactor breaking is the loudest: the contactor is attracted by the coil and presses this contactor against an electrical track with its mechanical inertia. The points P2 represent the moment when the noise of the contactor breaking is the quietest: the contactor is pushed back by the elastic means to its rest position, i.e. normally open.

[0080] The six beats are not audible, but the points PI and P2 are and mark the beginning and end of each beat.

[0081] Equivalently, we can consider instead of closing times, the opening times. For example, a first opening time is determined by t2 tn and so on. In [Fig.3] the closing times and the opening times are symmetrical, in both cases this represents an SOS signal, but this is not obligatory and, for example, the commands of the electromechanical switch K4, K5 can be pulses: the closing time is close to zero so that the noises at positions PI and P2 are confused, but the opening times correspond to the SOS signal in Morse code and thus the emitted sound signal, although pulsed, will be recognized as an SOS signal. In all cases, there will be at least three close commands, followed by three less close commands, thus forming the SOS sequence.

[0082] The other sequences are, for example, commands with constant closing time and opening time, but whose frequency of commands varies: from 40 to 210 commands per minute for example, to draw a parallel with the heart rates as previously explained. Similarly, this frequency can vary continuously from a minimum value to a maximum value depending on the thermal state of traction battery B, for example this frequency increasing with an increase in the temperature of battery B without it necessarily being a thermal runaway state. Thus the intervention personnel can know if the state of traction battery B is worsening, stabilizing or tending towards a stable thermal state before any alert on a thermal runaway state.

[0083] For example, the method may combine this increasing frequency with an increase in the temperature of battery B during non-thermal runaway, and apply the SOS sequence if thermal runaway is detected by the BMS control device.

[0084] This method advantageously applies to the vehicle described above, this motor vehicle comprising the electric traction battery B, this traction battery B comprising: - the BMS control device of the traction battery B, comprising the means of acquisition, processing by software instructions stored in a memory as well as the control means required for implementing the method described above, and - the electromechanical switch K4, K5 comprising the open position E0 and the closed position El controlled by the control device BMS according to the method previously described.

[0085] This vehicle comprises for example the electrical component M, C, CV, CV2 powered by the traction battery B, this traction battery B comprising the electrical isolation means DI of the traction battery B with respect to this electrical component M, C, CV, CV2, this isolation means DI comprising the redundant cut-off means K4, K5 controlled by the traction battery control device BMS, the electromechanical switch K4, K5 being one of these redundant cut-off means K4, K5.

[0086] This vehicle further comprises, for example, the electrical power supply system CV2, BS2 of the BMS control device, this power supply system CV2, BS2 comprising the second electrical battery BS2 for powering the BMS control device.

Claims

Claims

1. Method for warning of a state of an electric traction battery (B) of a vehicle, this battery (B) comprising: - a control device (BMS) of the traction battery (B), comprising the means of acquisition, processing by software instructions stored in a memory as well as the control means required for implementing the method, and - an electromechanical switch (K4, K5) comprising an open position (EO) and a closed position (El) controlled by the control device (BMS), this control device (BMS) of the traction battery (B) being configured to detect the state of the battery (B) and acquire information of occurrence of an impact against the vehicle, characterized in that if the information of occurrence of the impact is acquired, this method executes a step of successive commands of the switch (K4,K5) from its open position (EO) to its closed position (El) so that the closed positions (El) follow a predetermined and repeated sequence dependent on the detected state.,

2. A method according to claim 1, the detected state being a thermal runaway state of the traction battery.

3. A method according to claim 2, said predetermined sequence being that of a Morse code call for help message.

4. Method according to claim 2, this predetermined sequence having identical closed position times (El) at a frequency of more than 100 commands per minute.

5. A method according to claim 1, the detected state being a non-thermal runaway state of the traction battery (B).

6. A method according to claim 5, said predetermined sequence having identical closed position times (El) at a frequency of less than 100 commands per minute.

7. Method according to claim 6, this predetermined sequence having identical closed position times (El) at a frequency of between 40 and 80 commands per minute, in particular 60 commands per minute.

8. Motor vehicle comprising an electric traction battery (B), this traction battery (B) comprising: - a control device (BMS) for the traction battery (B), comprising the means of acquisition, processing by software instructions stored in a memory as well as the control means required for implementing a method according to one of the preceding claims, and - an electromechanical switch (K4, K5) comprising an open position (E0) and a closed position (El) controlled by the control device (BMS) according to the method.

9. Vehicle according to claim 8, the vehicle comprising an electrical member (M, C, CV, CV2) powered by the traction battery (B), this traction battery (B) comprising a means of electrical isolation (DI) of the traction battery (B) with respect to this electrical member (M, C, CV, CV2), this isolation means (DI) comprising redundant cut-off means (K4, K5) controlled by the traction battery control device (BMS), the electromechanical switch (K4, K5) being one of these redundant cut-off means (K4, K5).

10. Vehicle according to claim 8 or 9, this vehicle comprising an electrical power supply system (CV2, BS2) of the control device (BMS), this power supply system (CV2, BS2) comprising a second electric battery (BS2) for powering the control device (BMS).

Images