Method for warning of the state of an electric traction battery

Abstract

A method for warning of the state of a vehicle's electric traction battery (B), this battery (B) comprising: - a traction battery control device (BMS), including means for data acquisition, processing via software instructions stored in memory, and the control means required to implement the method, and - an electromechanical switch comprising an open position and a closed position controlled by the control device (BMS), this traction battery control device (BMS) being configured to detect the state of the battery (B) and acquire information indicating the occurrence of a collision with the vehicle, and if information indicating the occurrence of the collision is acquired, this method executes a step of successive commands of the switch from its open position to its closed position such 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 the state of an electric traction battery

[0001] Motor vehicles comprising an electric drive machine mechanically coupled to a wheel assembly or to a wheel, also include 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 higher electrical energy storage capacity than conventional lead-acid service batteries, and comprise a multitude of electrochemical cells generally connected in series to each other by block, 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 a fire to start which then spreads to neighboring cells and thus creating what a person skilled in the art calls a 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 to the traction battery.

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

[0006] Unfortunately, this signaling mechanism may be inoperable after such an accident, so that even if thermal runaway is detected and signaled by the traction battery control device, it is not certain that either the occupants or the occupant rescue personnel will be warned of the onset of thermal runaway. This is detrimental because this information about thermal runaway could lead the occupant rescue personnel to change their decision, as well as alert the occupants that, despite being in shock, they should not remain in the vehicle's passenger compartment.

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

[0008] To this end, the invention relates to a method for warning of the state of an electric traction battery of a vehicle, this battery comprising: - a traction battery control device, including the means for data acquisition, processing via software instructions stored in memory, and the control means required to implement the process, 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 of the occurrence of a collision against the vehicle, and if the information of the occurrence of the collision 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 components of the vehicle in the event of a collision. The probability that the control device will be operational after such a collision is high, whereas the signaling device is more likely to be out of service. The electromechanical switch is also protected against this collision, and has a disadvantage that is transformed into an advantage by this invention: when it is activated, whether it changes from an open to a closed state or vice versa, it makes noise. This noise is audible from outside the vehicle, sometimes amplified by the resonating chamber of a hermetically sealed casing forming an outer enclosure of the traction battery. Activating this electromechanical switch after the collision then makes it possible to send a signal to emergency personnel even if the signaling device is out of service.The sequence used by the process 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 thermal runaway state of the traction battery.

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

[0012] According to one 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 is important to note here the considerable advantage this provides to emergency personnel: This information is extremely useful because, apart from this invention, emergency personnel have no way of knowing whether the control device is still operational and capable of detecting or determining thermal runaway. In case of doubt, emergency personnel may rush their actions to the detriment of the occupants when, from the battery's point of view, there is no emergency. Our invention, from this perspective, reassures emergency 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 with regard to 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 specifically, 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 should 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, particularly above 100, intuitively suggests the idea of ​​danger, while below 100, it intuitively suggests a normal situation... of the traction battery. The ultimate danger can be signified by a frequency of 180 to 210, for example, while a normal situation corresponds, for example, to a frequency around 60, or between 40 and 80. The invention describes frequency ranges here; it is clear that this invention also covers the case of a continuously varying frequency, for example, ranging from 60 to 210, this variation being a function of the variation in the battery's state, for example, a function of its temperature increase.

[0018] The invention also relates to a motor vehicle comprising an electric traction battery, this traction battery comprising: - a traction battery control device, including means for data acquisition, processing via software instructions stored in memory, and the control means required to implement a process 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 includes an electrical component powered by the traction battery, this traction battery including a means for electrically isolating the traction battery from this component, this isolation means including redundant switching means controlled by the traction battery control device, the electromechanical switch being one of these redundant switching means.

[0020] Indeed, it is advantageous that the actuation of the electromechanical switch does not by itself cause a short circuit, particularly if the electrical component is itself short-circuited. Also, when the traction battery is isolated Through the isolation mechanism, the fact that the electromechanical switch is redundant ensures that, even when activated, the traction battery remains isolated from the electrical system. This redundancy is pre-existing on these vehicles, as will be detailed later.

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

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

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

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

[0025] These features ensure the operability of the control device and the electromechanical switch. For example, this second electric battery is housed inside the hermetically sealed casing of the traction battery, in a location well protected from vehicle impacts. The objective is to ensure that the noise, and therefore the audible sequence emitted by the electromechanical switch, remains 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 hermetically sealed housing of the traction battery, this housing also housing the cells and / or modules of the traction battery and the traction battery control device.

[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 lack of connection of the traction battery to the electrical component, and thus autonomously detect the battery's status and whether the battery is not mounted. If the traction battery is not mounted, this control device executes a series of commands from the switch 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 become apparent from the following description of a particular, non-limiting embodiment of the invention, made with reference to Figures 1 to 3 in which:

[0029] [Fig.1]: represents an internal diagram of an electric traction battery to 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 power supply system for the control device according to the invention.

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

[0032] In what follows, reference is made to Figures 1 and 2 taken together. 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.1], of an electric traction battery B to 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 those skilled in the art know, electrochemical cells CL grouped into modules MO, these modules MO being connected together in series and / or in parallel and delivering at 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 voltage converter CV. This low-voltage network, also called the vehicle's on-board network, is powered by a service battery BS with a lower voltage than the traction battery B, for example, a DC voltage between 10 and 30V, particularly 12V. This service battery BS is recharged by the voltage converter CV. Note that in [Fig. 2], the high-voltage network is represented by a double solid line, while the low-voltage network is represented by a dashed line.

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

[0037] Thus the high voltage network comprises a main positive branch coming out of a positive terminal of the traction battery B and being connected to the positive pole of the electric machine M, and a main negative branch coming out of a negative terminal of the traction battery B and 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 station external to the vehicle, in particular a charging station of a terrestrial electrical network, we then speak of an on-board charger C.

[0039] The traction battery B can therefore power the on-board network via the DC to DC converter CV.

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

[0041] The electronic control unit can act as a vehicle supervisor, managing information exchange via a CAN communication network with other computers, sensors, and vehicle subsystems. One of these other computers is a traction battery management system (BMS) control device included in traction battery B. The acronym BMS stands for Battery Management System, as shown in Figure 2.

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

[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 includes an isolation device DI, shown in [Fig. 2], designed to disconnect the power supply from the high-voltage network, and in particular the power supply to the electric machine M, the converter CV, and all electrical components electrically connected to the traction battery B via the high-voltage network. This isolation device DI may include branches connecting the traction battery B to the charger C, and optionally to the converter CV.

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

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

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

[0048] Voltages U1 to U6 for the positive branches of the isolation device DI, connected directly or indirectly to the positive terminal of the traction battery B, and voltages U00, U01, U02 for the negative branches of the isolation device DI, connected directly or indirectly to the negative terminal of the traction battery B, are shown in [Fig. 1] at specific points of the isolation device 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 operating.

[0049] Thus, switches K1 to K3 allow the traction battery B to be isolated from any electrical component, so that the switching means K4 and K5 are, for example, redundant switching means, as are fuses F2 and F3 if they are controlled by the traction battery B's BMS control device, which is the case, for example, with pyrotechnic fuses. Thus, for example, if 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 switches K4 and K5 will have no effect on this electrical isolation of the traction battery B. Thus, if switch K4 is an electromechanical switch, it can be controlled by the traction battery BMS control device according to the method of the invention, so as to emit a noise audible from outside the vehicle by a succession of clicking of the electromechanical switch.

[0050] Also, but less safely, if switch K3 is open, the negative branch of traction battery B is isolated from the electrical components M, C, CV which are connected to it, so 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 process, 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 alternately to electrical components M, C, CV which, as explained previously, is not entirely safe.

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

[0052] It should be noted that the electromechanical switch according to the invention is not necessarily a means of cutting off the isolation means DI. For example, this electromechanical switch, in a variant not shown, is a switch activating a system powered 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 means of isolation or simply not cut off at all: for example a system for evacuating condensation water that has occurred inside a hermetically sealed 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 means of isolation.

[0053] Figure 2, as already explained, further reveals an example of the CV2, BS2 power supply system of the traction battery control device BMS according to the invention. Figure 2 shows the high-voltage network in double solid lines, as well as the on-board network in dashed lines. The isolation means DI is represented schematically as a rectangle within which the electrical switches K1 to K5 and the fuses F2, F3 of Figure 1 are shown, although they are not shown in Figure 2. Some electrical components are shown, such as the electric drive machine M, as well as the converter CV. Figure 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 specifically for recharging the second BS2 battery from the high-voltage network.

[0054] It should be noted that the traction battery B comprises the hermetically sealed casing CH, this hermetically sealed 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 electric CV2, BS2 of the traction battery control device BMS, which has the advantage of keeping all the safety functions of the traction battery B under the protection of the hermetically sealed casing CH, but this is not mandatory because for example the electric power supply system CV2, BS2 could be outside the hermetically sealed casing CH, or even the control device BMS.

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

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

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

[0058] According to a variant of the invention, not shown, the power supply system of the control device (BMS) comprises only the second current converter CV2, electrically coupled to the traction battery and dedicated solely to powering the traction battery's BMS control device. According to this variant, this power supply system is entirely housed within the hermetically sealed casing CH of the traction battery, this casing also housing the CL cells and / or the MO modules of the traction battery B. This second converter CV2 is directly connected to the CL cells of battery B, bypassing the isolation device DI.Thus, the power supply system of the BMS control unit is entirely housed within the hermetically sealed CH casing of the traction battery B. This casing also houses the traction battery cells and / or modules and the traction battery BMS control unit. For example, in a situation where the traction battery B is not yet installed in the vehicle, such as during delivery of the traction battery B to the vehicle assembly plant, this traction battery BMS control unit will be configured to detect this situation, for example, by detecting a lack of connection. from the traction battery B to the electrical component M, and thus autonomously detect the state of the battery and the situation of the battery not mounted, and if the traction battery is not mounted, 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 includes means for detecting shocks or accidents, for example acceleration sensors housed in different locations on the bodywork, the electronic control unit being configured to receive information from these sensors, and to process it in order to deduce the occurrence of a shock or accident, which is perfectly known to those skilled in the art.

[0060] It is also known that, upon detection of such an impact, the electronic control unit triggers means of protection for the vehicle's occupants, including well-known means such as pyrotechnic airbags or seatbelt pretensioners. This same electronic control unit communicates this impact information to the BMS control device via the CAN network, and based on this impact information, the BMS control device will control the DI isolation device while monitoring the status of the traction battery B.

[0061] It should also be noted that, alternatively, the shock detection and the control of the means of protection of the occupants can be carried out by a third dedicated computer called the 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 state of thermal runaway initiated by at least one CL cell of the traction battery B. This information on the state of thermal runaway is communicated via the CAN network to the electronic control unit.

[0063] This determination of the thermal runaway state is regulated. In the event of a fire in the traction battery B, it allows the driver to be informed by a display on the dashboard, accompanied by an audible warning on the dashboard: "Battery temperature high: Stop as soon as possible and leave the vehicle." The aim is to inform the driver while giving them sufficient time (at least 5 minutes) to stop the vehicle, ideally in an open area, and allow them to evacuate the occupants safely before the fire spreads from the battery (should this occur).

[0064] This determination of the state of thermal runaway, and by extension the state of non-thermal runaway, is carried out to protect the occupants, in particular against an internal short circuit in a CL cell, which would ignite that CL cell, a fire that would then spread to several neighboring cells, thus creating an "exponential" runaway effect. This determination is mitigated by manufacturing defects in the CL cells (impurities on the separator) or excessive lithium plating that could breach the separator of a single cell.

[0065] The principle of determining thermal runaway is to recognize the signatures of fire ignition on a (first) CL cell. Several solutions exist: a pressure sensor can be installed to detect a rapid pressure increase; an abnormal voltage drop, a cell temperature increase, or a loss of insulation can also be detected. Since the alert is alarming and potentially worrying, it is essential to ensure it is triggered appropriately. For this reason, a combination of these principles is generally used, as these methods are 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 regulations, and in crashes resulting from tests defined by organizations such as EURO NCAP. In all these crash scenarios, the manufacturer can guarantee that the battery will not catch fire, that there will be no cell damage, and that there will be no short circuits on the busbars, for example. However, in very high-speed crashes where emergency services will intervene to extricate the vehicle's occupants, these first responders need to know the severity of the situation in the traction battery in order to adopt an appropriate extrication strategy:

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

[0068] Conversely, if the traction battery B can indicate a risk of fire starting soon, then this information is very useful, and allows for prioritizing a rapid extrication.

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

[0070] The electromechanical switch K4, K5 is, for example, an electromagnetic relay, comprising a magnetic coil controlled and powered by the BMS control device, 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 an initial clicking noise while allowing the passage of a power current, for example. Then, when this coil When the current is no longer supplied, the contactor will elastically return to its open position, and when it reaches its fully open end, it will make a second clicking noise. Other variations 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 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] Figure 3 discloses a method according to the invention.

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

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

[0075] This detected state is, for example, one of the following states: - 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 distress message. Alternatively, this predetermined sequence has identical closed position times El 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 presents identical closed position times El 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] Figure 3 in particular illustrates one example of these sequences in the case of detection and / or determination of the thermal runaway state of the battery. traction B, this predetermined sequence being that of a Morse code distress message. This [Fig. 3] illustrates a diagram representing the successive closed (EL) and open (EO) states E according to this Morse code sequence, therefore as a function of time t. The points PI represent the closing times of the electromechanical switch K4, K5, that is, the times when the BMS control device commands the closing of this switch and it is actually closed: these times are tb, t2, t3, t4, t5, t6. By symmetry, the points P2 represent the opening times of the electromechanical switch K4, K5, that is, the times when the BMS control device commands the opening of this switch and it is actually open: these times are 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 observe that the first three beats are shorter than the last three beats, this six-beat sequence repeating and thus recalling the SOS signal in Morse code.

[0079] For the previously described example of the electromechanical switch, namely a monostable switch in the open position, points P1 represent the moment when the contactor's clicking noise is loudest: the contactor is attracted by the coil and, with its mechanical inertia, presses against an electrical track. Points P2 represent the moment when the contactor's clicking noise is 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 audible and mark the beginning and end of each beat.

[0081] Equivalently, opening times can be considered instead of closing times. For example, a first opening time is determined by t2 tnet and so on. In [Fig. 3], the closing and opening times are symmetrical; in both cases, this represents an SOS signal, but this is not mandatory. For example, the commands of the electromechanical switch K4, K5 can be pulses: the closing time is close to zero, so the noises at positions P1 and P2 are indistinguishable, but the opening times correspond to the SOS signal in Morse code, and thus the emitted sound signal, although impulsive, will be recognized as an SOS signal. In all cases, there will be at least three closely spaced commands, followed by three less closely spaced commands, thus forming the SOS sequence.

[0082] The other sequences are, for example, commands with constant opening and closing times, but whose command frequency varies: from 40 to 210 commands per minute, for example, to draw a parallel with heart rates as previously explained. Similarly, this frequency can vary continuously fluctuates from a minimum to a maximum value depending on the thermal state of traction battery B; for example, this frequency increases with a rise in battery B's temperature without necessarily indicating a thermal runaway. This allows emergency personnel to determine whether traction battery B's condition is worsening, stabilizing, or approaching a stable thermal state before any thermal runaway alert is triggered.

[0083] For example, the method can combine this increasing frequency with a rise 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 is advantageously applicable to the vehicle described above, this motor vehicle comprising the electric traction battery B, this traction battery B comprising: - the traction battery BMS control device, including the means for data acquisition, processing via software instructions stored in memory, and the control means required to implement the process described above, and - the electromechanical switch K4, K5 comprising the open position E0 and the closed position El controlled by the BMS control device according to the previously described process.

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

[0086] This vehicle further includes, for example, the CV2, BS2 power supply system of the BMS control device, this CV2, BS2 power supply system including the second BS2 electric battery to power the BMS control device.

Claims

Demands

1. A method for warning of the state of an electric traction battery (B) of a vehicle, said battery (B) comprising: - a traction battery (BMS) control device, including means for data acquisition, processing by software instructions stored in memory, and 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), said traction battery (BMS) control device being configured to detect the state of the battery (B) and acquire information on the occurrence of a collision with the vehicle, characterized in that if the collision information 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) such that the closed positions (El) follow a predetermined and repeated sequence dependent on the detected state.

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

3. Method according to claim 2, this predetermined sequence being that of a Morse code distress 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. Method according to claim 1, the detected state being a state of non-thermal runaway of the traction battery (B).

6. Method according to claim 5, this 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 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 traction battery (B) control device (BMS), including the means of acquisition, processing by software instructions stored in a memory as well as the control means required to implement a process 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 process.

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

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

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