FR3136202A1 - MONITORING OVERVOLTAGES AT THE TERMINALS OF AN ELECTRIC MOTOR MACHINE OF A VEHICLE - Google Patents

Abstract

A monitoring method is implemented in a vehicle comprising a rechargeable main battery, having a maximum voltage at its terminals and coupled in a controlled manner, via a power supply network capable of being the subject of an active current discharge, to an electric motive machine having a measurable voltage at its terminals. This method comprises a step (10-40) in which, when the measured voltage is greater than a first chosen threshold and greater than the maximum voltage, the main battery is decoupled from the power supply network, then active discharge is carried out. Figure 3

Description

MONITORING OVERVOLTAGES AT THE TERMINALS OF AN ELECTRIC MOTOR MACHINE OF A VEHICLE Technical field of the invention

The invention relates to vehicles comprising a rechargeable main battery and coupled in a controlled manner, via a power supply network, to an electric motive machine, and more precisely the monitoring of such an electric motive machine.

State of the art

Certain vehicles, possibly of the automobile type, include a main (or traction) battery that is rechargeable and coupled in a controlled manner, via a power supply network (sometimes called "high voltage"), to an electric motor machine forming part of a group powertrain (or GMP).

Here we mean "main (or traction) battery" a battery responsible for supplying electric current via a supply network to an electric motive machine forming part of the GMP of its vehicle and a converter responsible, in particular, for supplying electric current to at least one on-board network of his vehicle.

Furthermore, the term “on-board network” is understood here as an electrical supply network to which electrical (or electronic) equipment (or components) which consume electrical energy are coupled.

In the aforementioned vehicles, an overvoltage may occur at the terminals of the electric motor, even though the latter is not designed for this purpose.

Currently, when such an overvoltage is detected, the vehicle driver is informed of an electrical fault and a loss of torque at the electric motor. But this can often prove insufficient, because this overvoltage can result from a failure of a resistive component of the electric motor machine and/or a failure of the power supply network to which the main battery is coupled and/or a failure of the main battery (and in particular of the associated isolation circuit (which notably includes contactors which can create overcurrents when they close)).

Indeed, the voltage at the terminals of the electric motor machine being equal to the product of the resistance of this electric motor machine and/or of the power supply network by the current supplied to this electric motor machine, when the voltage increases this results from an increase in resistance and/or current supplied.

Increasing the resistance of the electric drive machine may cause overheating of at least one electrical component of the electric drive machine, which may damage the electric drive machine and/or cause a fire in the vehicle.

The increase in the resistance of the power supply network is currently undetected, although it can damage the power supply network and/or induce a fire in the vehicle and/or cause electrocution of a passenger in the vehicle and/or or a person located outside the vehicle and touching it.

The increase in the current supplied generally results from a malfunction of the main battery (and in particular the associated isolation circuit) and/or the electric motor, which can damage the latter and/or cause a fire in the vehicle and /or cause electrocution of a passenger in the vehicle and/or a person located outside the vehicle and touching it. However, such a malfunction may not be detected by the computer which controls the operation of the main battery, and therefore it cannot be reported to the computer which supervises the operation of the GMP.

In all cases, notifying the driver of an electrical fault and a loss of torque will not stop the overvoltage. The invention therefore aims in particular to improve the situation.

Presentation of the invention

It proposes in particular for this purpose a monitoring method intended to be implemented in a vehicle comprising a main rechargeable battery, having a maximum voltage at its terminals and coupled in a controlled manner, via a power supply network which can be subject to 'an active discharge of current, to an electric motor machine having a measurable voltage at its terminals.

This monitoring method is characterized by the fact that it comprises a step in which, when this measured voltage is greater than a first chosen threshold and greater than this maximum voltage, the main battery is decoupled from the power supply network, then we carry out this active discharge.

Thanks to the invention, the overvoltage at the terminals of the electric motor machine is put an end to, thus making it possible to avoid damage to this electric motor machine and/or electrical equipment(s) coupled to the power network, and the power network is actively discharged of its current, thus preventing the passengers of the vehicle and/or people located outside the vehicle from running a risk.

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

- in its step, the main battery can be decoupled from the power supply network and active discharge can be carried out when the measured voltage is greater than the first threshold for a duration which is greater than a second chosen threshold;

- in the presence of the first option, in its step the second threshold can be between 5 ms and 50 ms;

- in its stage, in the presence of a maximum voltage equal to 450 V, the first threshold can be between 460 V and 500 V;

- in its stage, in the event of decoupling of the main battery from the power network, active discharge can be carried out and also carried out in the vehicle at least one complementary action chosen from generating an alert from a user of the vehicle requiring a stop of the latter and a need to have the vehicle checked, a recording of at least one fault code representative of an overvoltage problem at the terminals of the electric motor machine, a cooling of the electric motor machine, and a prohibition recovery of braking energy by the electric driving machine;

- in its step, the coupling of the main battery to the power network can be re-authorized after waking up the vehicle after falling asleep in the presence of decoupling of the main battery from the power network, provided that the measured voltage is lower than a third chosen threshold for a duration greater than a fourth chosen threshold;

- in the presence of the last option, in its step the third threshold can be equal to the first threshold.

The invention also proposes a computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing a monitoring method of the type of that presented above to monitor a voltage measured at the terminals of an electric driving machine fitted to a vehicle comprising a rechargeable main battery, having a maximum voltage at its terminals and coupled in a controlled manner, via a power supply network which can be subject to an active discharge of current, to this electric motor machine.

The invention also proposes a monitoring device intended to equip a vehicle comprising a rechargeable main battery, having a maximum voltage at its terminals and coupled in a controlled manner, via a power supply network capable of being the subject of an active discharge of current, to an electric motor machine having a measurable voltage at its terminals.

This monitoring device is characterized by the fact that it comprises at least one processor and at least one memory arranged to carry out the operations consisting, when this measured voltage is greater than a first chosen threshold and greater than this maximum voltage, in triggering a decoupling the main battery from the power supply network, then triggering this active discharge.

The invention also proposes a vehicle, possibly of the automobile type, and comprising:

- a main rechargeable battery, having a maximum voltage at its terminals and coupled in a controlled manner, via a power supply network capable of being the subject of an active current discharge, to an electric motor machine having a measurable voltage at its terminals , And

- a monitoring device of the type presented above.

Brief description of the figures

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

schematically and functionally illustrates an exemplary embodiment of a vehicle comprising a GMP, with an electric driving machine coupled, via a power supply network, to a main rechargeable battery, and a monitoring device according to the invention,

schematically and functionally illustrates an exemplary embodiment of a GMP supervision calculator comprising an exemplary embodiment of a monitoring device according to the invention, and

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

Detailed description of the invention

The invention aims in particular to propose a monitoring method, and an associated monitoring device DS, intended to allow monitoring of the voltage um measured at the terminals of an electric motor machine MME of a vehicle V which also comprises a main (or traction) battery BP rechargeable and coupled in a controlled manner, via a power supply network RA (sometimes called "high voltage"), to this electric motor machine MME, in order to detect possible overvoltages.

In what follows, we consider, by way of non-limiting example, that the vehicle V is of the automobile type. This is for example a car, as illustrated in the . But the invention is not limited to this type of vehicle. It concerns in fact any type of vehicle comprising a rechargeable main battery (in mode 2 or 3 and/or mode 4) and coupled in a controlled manner, via a power supply network, to an electric motor machine. Thus, it concerns, for example, land vehicles (utility vehicles, motorhomes, minibuses, coaches, trucks, motorcycles, road machinery, construction machinery, agricultural machinery, leisure machinery (snowmobile, kart), and road machinery. caterpillar(s), for example), boats and aircraft.

Furthermore, we consider in what follows, by way of non-limiting example, that the vehicle V comprises a powertrain (or GMP) of all-electric type (and therefore whose traction is ensured exclusively by at least one electric driving machine MRS). But the GMP could be of hybrid type (thermal and electric).

We have schematically represented on the a vehicle V comprising an electric GMP transmission chain (and therefore an MME electric driving machine), an on-board network RB, a service battery BS, a main (or traction) battery BP, a CV converter, a network of RA power supply, and a DS monitoring device according to the invention.

The RB on-board network is a very low voltage electrical supply network to which electrical (or electronic) equipment (or components) which consume electrical energy are coupled.

The utility battery BS is responsible for supplying electrical energy to the on-board network RB, in addition, here, to that supplied by the CV converter powered by the main battery BP via the power network RA, and sometimes to the place, here, this CV converter. For example, this BS utility battery can be arranged in the form of a very low voltage type battery (typically 12 V, 24 V or 48 V). It is rechargeable at least via the CV (current) converter. We consider in the following, by way of non-limiting example, that the BS utility battery is of the 12 V Lithium-ion type.

The transmission chain has a GMP which is, here, purely electric and therefore which includes, in particular, an electric driving machine MME, an AM motor shaft, and an AT transmission shaft. Here we mean “electric driving machine” an electric machine arranged so as to provide torque to move the vehicle V when it is supplied with electrical energy (here) by the main battery BP, as well as possibly to recover torque in regenerative braking.

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

The electric driving machine MME is here coupled, in a controlled manner and via the power supply network RA, to the main battery BP, in order to be supplied with electrical energy, as well as possibly to supply this main battery BP with electrical energy , particularly during regenerative braking. The operation of the MME electric driving machine is controlled by a CM machine computer.

This electric motor machine MME has a voltage at its terminals um which is measurable, for example by means of a voltage sensor.

Furthermore, the electric driving machine MME is coupled to the motor shaft AM, to provide it with torque by rotational drive. This motor shaft AM is here coupled to a reduction gear RD which is also coupled to the transmission shaft AT, itself coupled to a first train T1 (here of wheels), preferably via a differential DF.

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

The CV converter is coupled, in a controlled manner and via the RA power supply network, to the main battery BP. It is also responsible, here, during the driving phases of the vehicle V, of converting part of the electric current stored in the main battery BP to supply the on-board network RB and the service battery BS with converted electric current (to recharge it). ).

Note, as illustrated non-limitatively in the , that the CV converter can be part of a CH charger also comprising a recharge calculator (not illustrated) responsible, at least, for controlling the recharges of the main battery BP.

The main (or traction) battery BP has a maximum voltage ubmax at its terminals corresponding, for example, to a maximum charge level. For example, this maximum voltage ubmax can be equal to 450 V.

This main (or traction) BP battery can, for example, include electrical energy storage cells, possibly electrochemical (for example of the lithium-ion (or Li-ion) or Ni-Mh or Ni-Cd type). Also for example, the main BP battery can be of the low voltage type (typically 450 V for illustration purposes). But it could be medium voltage or high voltage.

It should also be noted that the main battery BP is associated with a battery box BB which notably includes a battery calculator CB, an isolation device DI, and voltage/current measuring means (not shown). This main battery BP and its battery box BB constitute a battery pack.

The isolation device DI is arranged so as to isolate, if necessary, the main battery BP from the CV converter and/or from the electric driving machine MME and/or from the charging connector CN making it possible to recharge the main battery BP when a Power cable (coupled to an external power source) is connected to it. For example, this DI isolation device may include contactors (or switches), possibly based on MOSFET(s) and each capable of taking an open (or non-conducting) state and a closed (or conducting) state. It is therefore inserted between the main battery BP and the part of the power supply network RA which is connected to the CV converter, between the main battery BP and the part of the power supply network RA which is connected to the electric motor machine MME, and between the CN charging connector and the part of the RA power supply network which is connected to the main battery BP (when mode 4 charging is possible).

It is preferably the CS supervision computer which decides on the opening or closing of selected contactors (or switches) of the DI isolation device.

It will also be noted that the power supply network RA can be the subject of an active current discharge once it has been decoupled from the main battery BP by action on at least one contactor (or switch) chosen from the device d DI isolation, and therefore once the main battery BP can no longer supply current to the RA power supply network. This active discharge is intended to consume all the current which was supplied to the power supply network RA by the main battery BP before decoupling, but which has not yet been consumed. For example, this consumption can be done by transforming the current which is still present in the RA power network into heat by means of at least one resistor dedicated for this purpose. Such a resistor can be part of the CH charger or (the electronics of) the MME electric motor machine.

It will also be noted that in the example illustrated non-limitingly on the , the vehicle V also includes a distribution box BD to which the utility battery BS, the CV converter and the on-board network RB are coupled. This distribution box BD is responsible for distributing in the on-board network RB the electrical energy stored in the utility battery BS or produced by the converter CV, for powering the electrical components (or equipment) coupled to the on-board network RB depending on power requests received (in particular from the GMP CS supervision computer).

As mentioned above, the invention notably proposes a monitoring method intended to allow monitoring of the voltage um measured at the terminals of the electric motor machine MME, in order to detect possible overvoltages.

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

The memory MD is RAM in order to store instructions for the implementation by the processor PR1 of at least part of the monitoring process. The processor PR1 may include integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or non-wired connections. By integrated (or printed) circuit we mean any type of device capable of performing at least one electrical or electronic operation.

In the example illustrated non-limitingly in Figures 1 and 2, the monitoring device DS is at least partially part (PR1 and MD) of the supervision computer (of the GMP) CS. But this is not obligatory. Indeed, the DS monitoring device could include its own dedicated computer, which is then coupled to the CS supervision computer, or could be part of another on-board computer, such as for example the CM machine computer or the battery computer. CB.

As illustrated without limitation on the , the (monitoring) method, according to the invention, comprises a step 10-40 which is implemented during the driving phases of the vehicle V.

Step 10-40 of the method comprises a sub-step 20 in which, when the measured voltage um is greater than a first threshold s1 which is chosen and greater than the maximum voltage ubmax, we decouple (the monitoring device DS triggers the decoupling of) the main battery BP from the power supply network RA. This amounts to completely isolating the main battery BP from the RA power supply network.

Step 10-40 of the method then comprises a sub-step 30 in which the active discharge of the power supply network RA is carried out (the monitoring device DS triggers the realization of). It is essential to carry out this active discharge of the RA power supply network once the latter (RA) has been decoupled from the main battery BP by action on the isolation device DI.

Decoupling the main battery BP from the power supply network RA advantageously makes it possible to put an end to the overvoltage at the terminals of the electric motive machine MME, which makes it possible to avoid damage to this electric motive machine MME and/or equipment. electrical (s) coupled to the RA power supply network (in particular the CV converter). The active discharge of the power supply network RA advantageously makes it possible to empty the latter (RA) of the current it contained before decoupling, and therefore allows the passengers of the vehicle V and/or people located outside the vehicle V are at risk of electrocution.

Note that in the presence of a maximum voltage ubmax equal to 450 V the first threshold s1 can, for example, be between 460 V and 500 V. As an illustrative example, the first threshold s1 can be equal to 470 V. But other values of first threshold s1 can be used. For example, the first threshold s1 can be chosen during the development phase of the vehicle V.

It should also be noted that the supervision computer CS prevents the battery computer CB, at the request of the monitoring device DS, from closing, on its own initiative due to the fact that it is not aware of the detected overvoltage, each contactor (or switch) having been opened in the isolation device DI to isolate the main battery BP from the power supply network RA.

It should also be noted that the supervision computer CS orders the recharge computer of the charger CH and/or the battery computer CB, at the request of the monitoring device DS, to carry out active discharge.

Also for example, and as illustrated non-limitingly on the , in order to make a decision in sub-step 20, we can provide a sub-step 10 of step 10-40 in which we (preferably the machine calculator CM) compare each measured voltage um to the first threshold s1. In this case, as indicated above, if a measured voltage um is lower than the first threshold s1 we return to carry out substep 10 with a new measured voltage um, while if a measured voltage um is higher than the first threshold s1 we ( the machine computer CM) informs the monitoring device DS, and the latter (DS) performs substeps 20 and 30 to at least decouple the main battery BP from the power network RA and carry out active discharge of the network RA power supply.

Note that in substep 20 of step 10-40 we (the monitoring device DS) can decouple (trigger the decoupling of) the main battery BP from the power supply network RA when the voltages um measured successively are all greater than the first threshold s1 for a duration which is greater than a second chosen threshold s2. This option makes it possible to avoid taking into account a single erroneous or occasionally abnormal measured voltage um (compared to the other voltages measured just before or just after) which would cause the immediate performance of main actions (i.e. decoupling of the battery main BP of the RA supply network and the active discharge of the RA supply network).

For example, the second threshold s2 can be between 5 ms and 50 ms. As an illustrative example, the second threshold s2 can be equal to 10 ms. But other values of second threshold s2 can be used. For example, the second threshold s2 can be chosen during the development phase of the vehicle V.

In order to determine the duration of an overvoltage problem at the terminals of the electric motor machine MME, we (the machine computer CM) can trigger in substep 10 a first time delay equal to the duration of the second threshold s2 as soon as the measured voltage um becomes greater than the first threshold s1 for the first time. When this duration of the second threshold s2 expires (and we still have um > s1), we (the machine computer CM) can inform the monitoring device DS, and the latter (DS) decides in substep 20 to decouple the main battery BP from the power network RA (then in substep 30 to at least carry out active discharge of the power network RA).

It will also be noted that in sub-step 30 of step 10-40, after the main battery BP has been decoupled from the power network RA in sub-step 20 and when the active discharge of the power network RA has been decided, it is also possible to carry out in the vehicle V at least one complementary action which is chosen from:

- generation of an alert from a user (or passenger) of vehicle V requiring a stop of the latter (V) and the need to have vehicle V checked,

- a recording of at least one fault code representative of an overvoltage problem at the terminals of the MME electric motor machine,

- cooling of the electric driving machine MME by means of a thermal regulation circuit (not illustrated) associated with the latter (MME), and

- a ban on recovery of braking energy by the MME electric driving machine when vehicle V is in a regenerative braking phase.

Preferably, the alert requires an emergency stop and is controlled by the supervision computer CS at the request of the monitoring device DS. In any case, the electric driving machine MME can no longer provide torque, and therefore the vehicle V can no longer travel other than freewheeling when its GMP is all-electric, or with its thermal engine when its GMP is hybrid.

This alert to the user of the vehicle V can be done, for example, by means of a light on (for example on the dashboard) and/or a message displayed on at least one screen of the vehicle V (for example of the dashboard or a central instrument panel) or on the screen of a smart phone (or “smartphone”) of the user, and/or broadcast by at least one speaker of the vehicle V or this phone clever.

The recording of at least one fault code representative of an overvoltage problem at the terminals of the MME electric motor machine is intended to facilitate the search for the origin of such an overvoltage by an after-sales service technician. , and to allow this technician to solve the problem and to inform the user of vehicle V of the origin of this overvoltage. For example, the machine computer CM can store a first fault code, then can inform the monitoring device DS so that it stores a second fault code (possibly different from the first fault code).

The prohibition of recovery of braking energy by the electric driving machine MME when the vehicle V is in a regenerative braking phase makes it possible to prevent the electric driving machine MME from supplying current to the power supply network RA in the event that the latter (RA) would be faulty. It is preferably the CS supervision computer which establishes this prohibition at the request of the DS monitoring device.

The cooling of the MME electric drive machine is intended to cool as quickly as possible each electrical component which may have been overheated. It can, for example, be done by activating the water pump of the thermal regulation circuit associated with the electric driving machine MME. It is preferably the supervision computer CS which establishes this cooling at the request of the monitoring device DS.

It will also be noted that step 10-40 can also include a sub-step 40 in which (the monitoring device DS) re-authorizes the coupling of the main battery BP to the power network RA after waking up the vehicle V subsequent to its falling asleep in the presence of decoupling of the main battery BP from the power supply network RA, provided that the measured voltage um is less than a third threshold s3 chosen for a duration which is greater than a fourth threshold s4 chosen.

Preferably:

- we also stop generating an (the DS monitoring device stops triggering the generation of an) alert for the user, when this additional action is planned,

- we also stop cooling (the monitoring device DS stops triggering the cooling of) the electric motor machine MME, when this additional action is planned, and

- we (the DS monitoring device) stop prohibiting the recovery of braking energy, when this additional action is planned.

Of course, if the measured voltage um is greater than the first threshold s1 or if the measured voltage um is less than the third threshold s3 for a duration which is less than the fourth threshold s4, the decoupling of the main battery BP from the power supply network RA is maintained.

For example, in step 10-40 the third threshold s3 can be equal to the first threshold s1. But this is not obligatory. Indeed, the third threshold s3 must be less than or equal to the first threshold s1 and greater than the maximum voltage ubmax.

Also for example, in step 10-40 the fourth threshold s4 can be equal to the second threshold s2. But this is not obligatory. Indeed, the fourth threshold s4 can be lower, equal to or higher than the second threshold s2.

Note also, as illustrated non-limitatively in the , that the supervision computer CS (or the dedicated computer of the monitoring device DS) can also include a mass memory MM1, in particular for the temporary storage of the measured voltages um and the contents of the overvoltage alert messages generated by the computer CM machine in the event of detection of an overvoltage, and any intermediate data involved in all its calculations and processing. Furthermore, this CS supervision computer (or the dedicated computer of the DS monitoring device) can also include an IE input interface for receiving at least the measured voltages um and the overvoltage alert messages, for the use in calculations or processing, possibly after having formatted and/or demodulated and/or amplified them, in a manner known per se, by means of a digital signal processor PR2. In addition, this CS supervision computer (or the dedicated computer of the DS monitoring device) can also include an IS output interface, in particular to deliver decoupling or re-coupling orders, orders to carry out an active discharge , orders prohibiting re-coupling, orders to start or stop operation of the thermal regulation circuit, user alert messages, and messages containing a fault code.

It will also be noted that the invention also proposes a computer program product (or computer program) comprising a set of instructions which, when executed by processing means of the electronic circuit (or hardware) type, such as for example the processor PR1, is capable of implementing the monitoring method described above to monitor the voltage um measured at the terminals of the electric motive machine MME of the vehicle V, in order to detect possible overvoltages.

Claims (10)

Monitoring method for a vehicle (V) comprising a rechargeable main battery (BP), having a maximum voltage at its terminals and coupled in a controlled manner, via a power supply network (RA) capable of being actively discharged current, to an electric motor machine (MME) having a measurable voltage at its terminals, characterized in that it comprises a step (10-40) in which, when said measured voltage is greater than a first chosen threshold and greater than said maximum voltage, said main battery (BP) is decoupled from said power supply network (RA), then said active discharge is carried out. Method according to claim 1, characterized in that in said step (10-40) said main battery (BP) is decoupled from said power supply network (RA) and said active discharge is carried out when said measured voltage is greater than said first threshold during a duration greater than a second chosen threshold. Method according to claim 2, characterized in that in said step (10-40) said second threshold is between 5 ms and 50 ms. Method according to one of claims 1 to 3, characterized in that in said step (10-40), in the presence of a maximum voltage equal to 450 V, said first threshold is between 460 V and 500 V. Method according to one of claims 1 to 4, characterized in that in said step (10-40), in the event of decoupling of said main battery (BP) from said power supply network (RA), said active discharge is carried out and we also carry out in said vehicle (V) at least one complementary action chosen from a generation of an alert from a user of said vehicle (V) requiring a stop of the latter (V) and a need to have said vehicle (V) checked ), a recording of at least one fault code representative of an overvoltage problem at the terminals of said electric motor machine (MME), a cooling of said electric motor machine (MME), and a prohibition of recovery of energy from braking by said electric motor machine (MME). Method according to one of claims 1 to 5, characterized in that in said step (10-40) the coupling of said main battery (BP) to said power supply network (RA) is re-authorized after waking up of said vehicle ( V) subsequent to falling asleep in the presence of decoupling of said main battery (BP) from said power supply network (RA), provided that said measured voltage is lower than a third chosen threshold for a duration greater than a fourth chosen threshold . Method according to claim 6, characterized in that in said step (10-40) said third threshold is equal to said first threshold. Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the monitoring method according to one of claims 1 to 7 to monitor a voltage measured at the terminals of an electric motor machine (MME) equipping a vehicle (V) comprising a rechargeable main battery (BP), having a maximum voltage at its terminals and coupled in a controlled manner, via a power supply network (RA) capable of subject to an active current discharge, to said electric motor machine (MME). Monitoring device (DS) for a vehicle (V) comprising a rechargeable main battery (BP), having a maximum voltage at its terminals and coupled in a controlled manner, via a power supply network (RA) capable of being subject to an active discharge of current, to an electric motor machine (MME) having a measurable voltage at its terminals, characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting of , when said measured voltage is greater than a first chosen threshold and greater than said maximum voltage, to trigger a decoupling of said main battery (BP) from said power supply network (RA), then to trigger said active discharge. Vehicle (V) comprising a rechargeable main battery (BP), having a maximum voltage at its terminals and coupled in a controlled manner, via a power supply network (RA) capable of being the subject of an active current discharge, to a electric motor machine (MME) having a measurable voltage at its terminals, characterized in that it further comprises a monitoring device (DS) according to claim 9.