FR3136608A1 - REDUNDANCY MONITORING OF TEMPERATURE MEASUREMENTS OF AN ELECTRIC MOTOR MACHINE OF A VEHICLE - Google Patents

Abstract

A monitoring method is implemented in a vehicle comprising an electric driving machine providing an output torque and periodically subject to at least two temperature measurements by at least two separate detectors. This method comprises a step (10-50) in which the temperature measurements are recovered, then a minimum value and a maximum value are determined among these recovered temperature measurements, and, when the difference between these maximum and minimum values is greater at a first chosen threshold, a chosen limitation of the output torque to be supplied is temporarily imposed. Figure 3

Description

REDUNDANCY MONITORING OF TEMPERATURE MEASUREMENTS OF AN ELECTRIC MOTOR MACHINE OF A VEHICLE Technical field of the invention

The invention relates to vehicles comprising an electric driving machine forming part of a powertrain, and more specifically the monitoring within such vehicles of the operation of temperature detectors associated with this electric driving machine.

State of the art

Certain vehicles, possibly of the automobile type, include a powertrain (or GMP) comprising an electric driving machine providing an output torque from electrical energy supplied, for example, by a main (or traction) battery or a battery fuel.

In the aforementioned vehicles, the electric driving machine is generally an electric motor comprising a rotor and a stator. When such an electric motor machine is in operation, for example to provide an output torque for the wheels of a train of its vehicle, its stator consumes electrical energy from the main battery to create at least one magnetic field intended to turn the rotor.

By way of example, when this electric motor machine is of the so-called “permanent magnet synchronous” type, it comprises a permanent magnet rotor and a stator comprising N coils (with N ≥ 3) placed around the rotor and powered, so controlled by a machine computer associated with the electric driving machine, in current pulses having directions of circulation chosen so as to make each of them attractive or repulsive or neutral (no current) at a precise instant. These current pulses are determined according to a setpoint defining the torque to be supplied by the electric motor (and therefore its rotor) on its output and which is determined by a vehicle GMP supervision calculator as a function of the percentage of depressing the accelerator pedal.

Due to its consumption of electrical energy in operation, the stator of the electric driving machine rises in temperature, and for it to operate correctly, without risk of degradation, its temperature must remain within a temperature range chosen (defined by minimum and maximum temperatures).

The temperature of the electric motor machine, and more precisely of its stator, is therefore subject to monitoring by periodic comparison to at least one chosen maximum temperature of the temperature measurements which are carried out periodically by a sensor associated with the stator of this electric driving machine. Thus, when the temperature measurement is higher than this maximum temperature, preferably for a duration greater than a chosen threshold, a chosen limitation of the output torque to be provided is imposed, as described in patent document EP-B1 3 151 394 In other words, the electric motor machine is forced to operate in a degraded mode (or in English "limp home") in which the output torque that it is authorized to provide is limited, in order to avoid degradation. of the electric driving machine, or even the outbreak of a fire, and thus protect the vehicle and its passengers. At the same time, when the electric motor is associated with a heat exchange device (at least allowing it to be cooled), this heat exchange device is operated so that the temperature measurement becomes lower than the maximum temperature again. As fast as possible.

A disadvantage of this mode of operation lies in the fact that the degraded operating mode of the electric motor is automatically decided as soon as the temperature measurement exceeds the maximum authorized temperature, without knowing whether this excess results from a malfunction of the electric motor machine or a malfunction of the temperature detector associated with the stator of this electric motor machine. Therefore, when a vehicle arrives at an after-sales service after having undergone at least one operation of its electric motor in the aforementioned degraded mode (or limp home), we generally proceed with the complete replacement of the electric motor (temperature detector included) even though it is possibly this temperature detector which is defective. Such replacement is very expensive for the vehicle manufacturer when the vehicle is under warranty, or for the vehicle owner when the warranty is no longer valid.

Another disadvantage of this mode of operation lies in the fact that the temperature measurement provided by the temperature detector can remain lower than the maximum temperature, even though in reality the effective temperature is already higher than this maximum temperature, due to of an undetected malfunction of this temperature detector. In such a situation, the control of the electric driving machine proves to be unsuitable for the situation in progress and can lead to a thermal runaway of the electric driving machine which can damage the latter, or even trigger a fire in the vehicle, causing a risk to the latter and its passengers, but also to people and objects located in the environment of the vehicle.

The invention therefore aims in particular to improve the situation.

Presentation of the invention

To this end, it proposes in particular a monitoring method intended to be implemented in a vehicle comprising an electric driving machine providing an output torque and periodically subject to at least one temperature measurement by at least one detector.

This monitoring method is characterized by the fact that it comprises a step in which at least two temperature measurements taken in different locations are recovered by at least two separate detectors associated with the electric motor machine, then a minimum value is determined. and a maximum value among these recovered temperature measurements, and, when a difference between these maximum and minimum values is greater than a first chosen threshold, a chosen limitation of the output torque to be provided is temporarily imposed.

Thanks to this redundancy monitoring of temperature measurements carried out at different locations on the electric motor machine, it is now possible to detect an operating problem with a temperature detector associated with this electric motor machine, thus making it possible to avoid a thermal runaway. of this electric motor machine and to differentiate an operating problem of a temperature detector from a problem of operation of the electric motor machine.

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 limitation can be temporarily imposed when successive deviations are 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 stage the second threshold can be between 50 ms and 500 ms;

- in its stage, the first threshold can be between 15°C and 35°C;

- in its stage, the limitation can consist either of a maximum torque chosen when the electric drive machine must provide a positive output torque, or in a minimum torque chosen when the electric drive machine must provide a negative output torque;

- in its stage, in the event of temporary imposition of the limitation, it is also possible to carry out in the vehicle at least one complementary action chosen from a generation of an alert of a user of the vehicle of this limitation, a recording of at least minus a fault code representative of a temperature difference problem, and cooling of the electric motor machine by means of a heat exchange device associated with the latter;

- in its step, we can re-authorize the use of the electric motor machine without the limitation when the successive temperature measurements are lower than a third chosen threshold for a duration which is greater than a fourth chosen 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 the operation of at least two separate detectors associated in different locations with an electric driving machine fitted to a vehicle, providing an output torque and periodically subject to temperature measurements by these detectors.

The invention also proposes a monitoring device intended to equip a vehicle comprising an electric driving machine providing an output torque and periodically subject to at least one temperature measurement by at least one detector.

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 of recovering at least two temperature measurements taken in different locations by at least two distinct detectors and associated with the electric motor machine, then to determine a minimum value and a maximum value among these recovered temperature measurements, and, when a difference between these maximum and minimum values is greater than a first chosen threshold, to trigger a temporary imposition of a chosen limitation of the output torque to be provided.

The invention also proposes a vehicle, possibly of the automobile type, and comprising an electric driving machine providing an output torque and being periodically subject in different locations to at least two temperature measurements by at least two separate detectors, which are associated with it, and a monitoring device of the type of that 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 motor powered by a rechargeable main battery and associated with temperature detectors, and a monitoring device according to the invention,

schematically and functionally illustrates an exemplary embodiment of an electric motor computer 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 redundant monitoring of the operation of temperature detectors Dk associated with the electric driving machine MME of a vehicle V.

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 powertrain (or GMP) comprising an electric driving machine supplied with electrical energy, for example by a main (or traction) battery or by a fuel cell, and associated with detectors of temperature. 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).

In addition, we consider in what follows, by way of non-limiting example, that the electric driving machine MME is supplied with electrical energy by a rechargeable main (or traction) battery during recharging phases. But the MME electric driving machine could be supplied with electrical energy by a fuel cell.

Finally, we consider in what follows, by way of non-limiting example, that the MME electric motor machine is of the so-called “permanent magnet synchronous” type. But other types of electric motor can be used, as long as they include a stator and a rotor.

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

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

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, and sometimes instead, here, of this converter RESUME. 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 an output 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 energy. torque during regenerative braking phases.

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

The electric driving machine MME (here a permanent magnet synchronous electric motor, as an example) is here coupled to the main battery BP, in order to be supplied with electrical energy, as well as possibly to power this main battery BP in electrical energy, particularly during regenerative braking. The operation of the MME electric driving machine is controlled by a CM machine computer.

Furthermore, the electric driving machine MME is coupled to the motor shaft AM, to provide it with an output 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.

In the example illustrated, the electric motor machine MME comprises a permanent magnet rotor RM and a stator SM comprising N coils Bn (with N ≥ 3) placed around the rotor RM and powered, in a manner controlled by the machine computer CM, in current pulses having directions of circulation chosen so as to make each of them attractive or repulsive or neutral (no current) at a precise moment. It will be understood that this rotational drive of the rotor RM makes it possible to produce engine torque to move the vehicle V.

It will be noted that in the example illustrated non-limitingly on the the SM stator includes three coils B1 to B3 (n = 1 to 3, N = 3). But the stator SM can include any number of coils Bn as long as this number is greater than or equal to three.

It will also be noted that in the example illustrated non-limitingly on the the SM stator is associated with three separate detectors D1 to D3 (k = 1 to 3), installed respectively in three different locations, and each responsible for periodically delivering mtk temperature measurements. But the stator SM can be associated with any number of detectors Dk as long as this number is greater than or equal to two.

The CV converter 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 converted electric current to the on-board network RB and the service battery BS (for the reload).

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

The main (or traction) battery BP 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. This main battery BP and its battery box BB constitute a battery pack.

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 proposes in particular a monitoring method intended to allow redundancy monitoring of the operation of the temperature detectors Dk distinct and associated with the electric motor machine MME (and more precisely with its stator SM).

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 part of the machine computer CM (associated with the electric motor machine MME). But this is not obligatory. Indeed, the monitoring device DS could include its own dedicated computer, which is then coupled to the machine computer CM, or could be part of another on-board computer (for example the supervision computer CS or the battery computer CB ).

As illustrated without limitation on the , the (monitoring) method, according to the invention, comprises a step 10-50 which is implemented when the GMP of the vehicle V is in operation, and in particular when the electric motive machine MME is in operation.

Step 10-50 of the method comprises a sub-step 10 in which (the monitoring device DS) recovers at least two temperature measurements mtk carried out in different locations by at least two temperature detectors Dk (associated with the machine electric motor MME).

Step 10-50 of the method also includes a sub-step 20 in which (the monitoring device DS) determines a minimum value vmin and a maximum value vmax among the mtk temperature measurements recovered in sub-step 10.

Step 10-50 of the method also includes a sub-step 40 in which, when the difference ev between the maximum vmax and minimum vmin values is greater than a first chosen threshold s1, a (the monitoring device DS) is temporarily imposed triggers the temporary imposition of a) chosen limitation of the output torque to be provided by the electric motor machine MME. In other words, the MME electric motor machine is forced to operate in a degraded mode (or limp home).

We consider in fact that it is impossible for a deviation ev greater than the first threshold s1 to be obtained when the temperature detectors Dk are all functioning correctly. Consequently, each time the deviation ev is greater than the first threshold s1 it is because at least one of the temperature detectors Dk has an operating problem, and therefore we act accordingly, at least by temporarily imposing a limitation chosen of the output torque to be provided by the electric driving machine MME, because at least one of the mtk temperature measurements is not reliable. There is in fact a risk that the CM machine computer makes potentially unsuitable decisions for the MME electric motor machine.

Thanks to this redundancy monitoring of mtk temperature measurements provided by different Dk temperature detectors, we avoid thermal runaway of the electric motor machine MME, and therefore we avoid degrading the latter (MME), or even triggering a fire in the vehicle V, which makes it possible to avoid putting the latter (V) and its passengers at risk, but also to the people and objects located in the environment of the vehicle V.

In addition, this allows the machine computer CM to differentiate an operating problem of a temperature detector Dk from an operating problem of the electric motor machine MME.

For example, and as illustrated without limitation on the , step 10-50 may include a sub-step 30 in which (the monitoring device DS) compares the deviation ev determined in sub-step 20 to the first threshold s1. In this case, as indicated above, if the determined deviation ev is less than the first threshold s1 we return to carry out substep 10, while if the determined deviation ev is greater than the first threshold s1 we carry out the substep 40 to temporarily impose a selected limitation on the output torque to be provided by the electric driving machine MME.

Also for example, the first threshold s1 can be between 15°C and 35°C. More preferably, the first threshold s1 is between 20°C and 30°C. As an illustrative example, the first threshold s1 can be equal to 25°C. But other values of first threshold s1 can be used. For example, the value of the first threshold s1 can be chosen during the development phase of the vehicle V. It will be noted that the value of the first threshold s1 depends in particular on the position of the temperature detectors Dk relative to the stator SM, the proximity to a possible heat exchange device DET (responsible at least for cooling the stator SM when this proves necessary), and the architecture of the electric motor machine MME.

It will be noted that in sub-step 30 of step 10-50 the limitation can consist either of a maximum torque chosen when the electric driving machine MME must provide a positive output torque (for forward travel), or of a torque minimum chosen when the MME electric driving machine must provide a negative output torque (for reverse gear).

Note that in sub-step 30 of step 10-50 we (the monitoring device DS) can optionally choose the value of the output torque limitation as a function of the sign, positive or negative, of the output torque in front of be supplied by the MME electric driving machine. In this case, in the case of providing a positive output torque, a first limiting value is used, and in the case of providing a negative output torque, a second limiting value is used. But you can also choose to use the same limitation value, to the nearest sign, for the positive output torque limitation and the negative output torque limitation. For example, the value of the positive output torque limitation may be equal to approximately +50 Nm, and the value of the negative output torque limitation may be equal to approximately -50 Nm.

It will also be noted that in sub-step 40 of step 10-50 we (the monitoring device DS) can temporarily impose the aforementioned limitation when successive deviations ev are greater than the first threshold s1 for a duration which is greater than one second threshold s2 chosen. This option makes it possible to avoid taking into account a single erroneous or occasionally abnormal ev deviation (compared to other ev deviations determined just before or just after) which would cause the immediate execution of a main action (i.e. the temporary imposition of limitation).

For example, the second threshold s2 can be between 50 ms and 500 ms. As an illustrative example, the second threshold s2 can be equal to 100 ms. But other values of second threshold s2 can be used. For example, the value of the second threshold s2 can be chosen during the development phase of the vehicle V.

In order to determine the duration of a temperature difference problem (and therefore of an operating problem of at least one of the temperature detectors Dk), we (the monitoring device DS) can trigger in the sub- step 30 a first time delay equal to the duration of the second threshold s2 as soon as the difference ev becomes greater than the first threshold s1 for the first time, and when this duration of the second threshold s2 expires (and we always have ev > s1 ), we decide in substep 40 to at least temporarily impose the limitation. If the difference ev becomes lower than the first threshold s1 again before the expiration of the duration of the second threshold s2, we (the monitoring device DS) returns to carry out substep 10.

It will also be noted that in sub-step 40 of step 10-50, when the temporary imposition of the limitation has been decided, it is also possible to carry out (the monitoring device DS can trigger the carrying out), in the vehicle V , at least one complementary action which is chosen from:

- the generation of an alert from a user (or passenger) of the vehicle V of this imposed limitation,

- the recording of at least one fault code representative of a temperature difference problem (and therefore of an operating problem of at least one of the temperature detectors Dk), and

- cooling the electric driving machine MME by means of the heat exchange device DET associated with the latter (MME).

The user of the vehicle V can be alerted, for example, by means of a lit indicator light (for example on the dashboard) and/or a message displayed on at least one screen of the vehicle V (for example example of the dashboard or a central handset) 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 smartphone. This alert is intended to notify the driver of a malfunction on the MME electric motor, so that he can quickly go with his V vehicle to an after-sales service to have it checked.

The recording of at least one fault code representative of a temperature difference problem is intended to facilitate the search for the origin of a limitation imposed by an after-sales service technician, and to allow this technician to resolve the problem and inform the user of vehicle V of the origin of such a limitation.

The cooling of the MME electric drive machine by means of the heat exchange device DET is intended to avoid a possible thermal runaway of the MME electric drive machine, despite the torque limitation imposed.

It will also be noted that step 10-50 can also include a sub-step 50 in which (the monitoring device DS) re-authorizes the current supply to the electric motor machine MME (and therefore the use of this last (MRS)).

It will also be noted that step 10-50 can also include a sub-step 50 in which it is considered that an operating problem of a temperature detector Dk (exceeding the first threshold s1) previously detected is no longer present when the successive mtk temperature measurements become lower than a third chosen threshold s3 for a duration which is greater than a fourth chosen threshold s4. In this case, we (the DS monitoring device) re-authorizes the use of the MME electric drive machine without the output torque limitation. Preferably, we also stop generating an (the DS monitoring device stops triggering the generation of a) alert for the user (when this additional action is planned). Of course, if the temperature difference problem is detected again, a new limitation is imposed on the MME electric driving machine.

For example, the third threshold s3 can be between 15°C and 35°C. More preferably, the third threshold s3 is between 20°C and 25°C. As an illustrative example, the third threshold s3 can be equal to 23°C. But other values of third threshold s3 can be used. For example, the value of the third threshold s3 can be chosen during the development phase of the vehicle V.

Also for example, the value of the fourth threshold s4 can be between 50 ms and 500 ms. As an illustrative example, the value of the fourth threshold s4 can be equal to 200 ms. But other values of fourth threshold s4 can be used. For example, the value of the fourth threshold s4 can be chosen during the development phase of the vehicle V.

Note also, as illustrated non-limitatively in the , that the machine computer CM (or the dedicated computer of the monitoring device DS) can also include a mass memory MM1, in particular for the temporary storage of successive mtk temperature measurements, and deviations ev determined successively, and possible intermediate data involved in all its calculations and processing. Furthermore, this CM machine calculator (or the dedicated calculator of the DS monitoring device) can also include an IE input interface for receiving at least the successive mtk temperature measurements, to use them in calculations or processing. , possibly after having shaped and/or demodulated and/or amplified them, in a manner known per se, by means of a digital signal processor PR2. In addition, this machine computer CM (or the dedicated computer of the monitoring device DS) can also include an output interface IS, in particular to deliver orders to limit the output torque, orders to cancel the limitation of the torque output, 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 redundantly monitor the operation of the temperature detectors Dk distinct and associated with the electric motive machine MME of the vehicle V.

Claims (10)

Monitoring method for a vehicle (V) comprising an electric motor machine (MME) providing an output torque and periodically subject to at least one temperature measurement by at least one detector (Dk), characterized in that it comprises a step (10-50) in which we recover at least two temperature measurements carried out in different locations by at least two detectors (Dk) distinct and associated with said electric motor machine (MME), then we determine a minimum value and a maximum value among said recovered temperature measurements, and, when a difference between said maximum and minimum values is greater than a first chosen threshold, a chosen limitation of said output torque to be provided is temporarily imposed. Method according to claim 1, characterized in that in said step (10-50) said limitation is temporarily imposed when successive deviations are greater than said first threshold for a duration greater than a second chosen threshold. Method according to claim 2, characterized in that in said step (10-50) said second threshold is between 50 ms and 500 ms. Method according to one of claims 1 to 3, characterized in that in said step (10-50) said first threshold is between 15°C and 35°C. Method according to one of claims 1 to 4, characterized in that in said step (10-50) said limitation consists either of a maximum torque chosen when said electric motor machine (MME) must provide a positive output torque, or in a minimum torque chosen when said electric motor machine (MME) must provide a negative output torque. Method according to one of claims 1 to 5, characterized in that in said step (10-50), in the event of temporary imposition of said limitation, at least one complementary action chosen from among said vehicle (V) is also carried out in said vehicle (V). generating an alert for a user of said vehicle (V) of said limitation, recording at least one fault code representative of a temperature difference problem, and cooling said electric motor machine (MME) by means of a heat exchange device (DET) associated with the latter (MME). Method according to one of claims 1 to 6, characterized in that in said step (10-50) the use of said electric motor machine (MME) is re-authorized without said limitation when said successive temperature measurements are less than a third threshold chosen for a duration greater than a fourth threshold chosen. 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 the operation of at at least two separate detectors (Dk) associated in different locations with an electric motor machine (MME) fitted to a vehicle (V), providing an output torque and periodically subject to temperature measurements by said detectors (Dk). Monitoring device (DS) for a vehicle (V) comprising an electric motor machine (MME) providing an output torque and periodically subject to at least one temperature measurement by at least one detector (Dk), characterized in what it comprises at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting of recovering at least two temperature measurements carried out in different locations by at least two distinct and associated detectors (Dk) to said electric motor machine (MME), then to determine a minimum value and a maximum value among said recovered temperature measurements, and, when a difference between said maximum and minimum values is greater than a first chosen threshold, to trigger an imposition temporary of a chosen limitation of said output torque to be provided. Vehicle (V) comprising an electric motor machine (MME) providing an output torque and periodically subject to at least one temperature measurement by at least one detector (Dk), characterized in that it comprises at least two detectors (Dk) distinct and associated in different locations with said electric motor machine (MME), and a monitoring device (DS) according to claim 9.