METHOD FOR MONITORING ENGINE TORQUE IN AN ELECTRIC VEHICLE MACHINE

Abstract

The invention relates to a method for monitoring the engine torque of an electric machine of a rear axle of a powertrain for an electrified vehicle, the method comprising determining a torque difference (EC) between a torque setpoint (CC) transmitted to the electric machine and a torque produced (CR) by the rotor of the electric machine, the method providing for acquiring an instantaneous speed (VV) of movement of the vehicle, the method providing for declaring a possible fault relating to the torque difference as a function of a zero or non-zero torque setpoint, as a function of an instantaneous direction of movement of the vehicle among forward and reverse gear, and as a function of the instantaneous speed of movement of the vehicle (VV) relative to a speed threshold.

Description

Title of the invention: METHOD FOR MONITORING ENGINE TORQUE IN AN ELECTRIC VEHICLE MACHINE

[0001] The field of the invention relates to a method for monitoring the engine torque delivered by an electric machine in an electrified vehicle (hybrid vehicle or 100% electric vehicle).

[0002] In the automotive industry, vehicle manufacturers integrate monitoring functions to ensure the proper functioning of the electric traction / propulsion machine(s). In particular, one of these functions consists of continuously monitoring the torque produced by the rotor of the electric machine by measuring it and comparing it to the instructed torque setpoint. If too large a deviation is detected, an alert is signaled and the electric machine is reconfigured in a degraded mode.

[0003] We are interested here in particular, but not exclusively, in an electric machine installed on the rear axle of a vehicle also comprising a main motor tractor unit on the front axle.

[0004] The electrical machine is controlled by a control unit via a power device called an inverter (or 'inverter' in the jargon of the trade) which includes power switches connected to the phases of the stator.

[0005] The sensors involved and the computing power available in the control unit must be optimized so as not to increase the cost of the electrical machine and its control.

[0006] Indeed, the control unit comprises a microcontroller which performs a plurality of tasks, some of which have a recurrence frequency proportional to the rotation speed of the rotor of the electrical machine. The tasks of controlling the phases and monitoring the delivered torque are among those whose call frequency is proportional to the writing speed.

[0007] Furthermore, for precision maneuvers at very low speed, the electric machine is required to provide the torque requested of it very precisely. This requirement, extrapolated to high rotation speeds, results in high constraints on the sequencing of tasks and the general computing load in the microcontroller.

[0008] Furthermore, if good precision is to be obtained at all rotation speeds, the sensors, particularly position sensors, arranged in the machine must have better sensitivity and are therefore more expensive.

[0009] The inventors therefore sought to propose an optimized solution to meet the functional needs while minimizing the cost of the solution.

[0010] For this purpose, the present invention proposes a method for monitoring the engine torque of an electric machine of an axle of a traction chain for an electrified vehicle, the method comprising the determination of a torque difference between a torque setpoint transmitted to the electric machine and a torque produced by the rotor of the electric machine, the method providing for an acquisition of an instantaneous speed of movement of the vehicle and an instantaneous direction of movement of the vehicle between forward and reverse gear, characterized in that the method provides for a recurrent application of the following logic: el- if the torque setpoint is zero, then declare a fault of a first type if the torque deviation EC is greater than a first threshold, e2- if the torque setpoint is non-zero, if the instantaneous direction of movement of the vehicle is forward and if the instantaneous speed of movement of the vehicle is less than a first speed threshold, then declare a fault of a second type if the torque difference is greater than a second threshold, e3- if the torque setpoint is non-zero, if the instantaneous direction of movement of the vehicle is forward and if the instantaneous speed of movement of the vehicle is greater than the first speed threshold, then declare a fault of a third type if the torque difference is greater than a third threshold, e4- if the torque setpoint is non-zero, if the instantaneous direction of movement of the vehicle is reverse and if the instantaneous speed of movement of the vehicle is less than a second speed threshold, then declare a fault of a fourth type if the torque difference is greater than a fourth threshold, e5- if the torque setpoint is non-zero, if the instantaneous direction of movement of the vehicle is reverse and if the instantaneous speed of movement of the vehicle is greater than the second speed threshold, then declare a fault of a fifth type if the torque difference is greater than a fifth threshold.

[0011] It should be noted that the third and fifth thresholds are larger than the other thresholds and that a lower precision of torque delivery is thus allowed in the high rotation speed ranges.

[0012] Thanks to the provisions promoted above, it is possible to obtain satisfactory operation of the motor for high rotation speeds and / or it is possible to limit the calculation load induced by the control of the phases and the calculation of the delivered torque and its comparison with respect to the thresholds.

[0013] It is also possible to keep sensors with good value for money, assuming that their performance is capped for high rotor rotation speeds.

[0014] The precision constraint on the delivered torque only applies for low speeds for which maneuvering precision is expected at the vehicle level.

[0015] It is noted that, according to a preferred configuration of the present invention, the axle considered here is the rear axle of a vehicle also comprising a main motor-tractor unit on the front axle (which may be purely electric, hybrid or thermal). In this configuration, the rear electric machine complements the motor-tractor unit on the front axle for the vehicle's drive, in particular to perform the 4x4 function ('All Wheel Drive' in the jargon). The main traction is provided by the front electric machine.

[0016] It should be understood here that the term “threshold” without complement designates a torque threshold, whereas the term “speed threshold” refers to a speed threshold.

[0017] As will be seen later, the periodicity of repetition of steps e1 to e5 is rapid, the corresponding task has high recurrence, for example every 10 milliseconds.

[0018] Advantageously, the first threshold is smaller than the other four thresholds. Indeed, if the torque setpoint is 0, it is necessary for the torque produced to be very close to 0 in practice, for example a value less than 1 Newton meter. This avoids a possible phenomenon of small jolts which may be felt by the occupants of the vehicle, for example in the case where the torque produced oscillates around 0 and exceeds the first prescribed threshold.

[0019] According to one embodiment, the method provides for a reconfiguration of the electrical machine in the event of declaration of a first type fault or a second type fault or a third type fault or a fourth type fault or a fifth type fault. A reconfiguration corresponds to a switch to degraded mode, i.e. a total or partial inhibition of torque delivery. There may be one or more types or levels of reconfiguration depending on the type of fault declared.

[0020] According to one embodiment, a fault is stored in a non-volatile memory of the microcontroller. This allows a maintenance service to retrieve information on the circumstances of the occurrence of the torque difference greater than the prescribed threshold, and to initiate a further diagnosis or carry out a repair. Even if the operation of the electrical machine returns to normal, the memory of a fault that has occurred persists and it can be read using a diagnostic tool or a remote diagnostic function.

[0021] According to one embodiment, the first speed threshold is between 3 km / h and 5 km / h. This relatively low speed threshold corresponds to parking maneuvers or maneuvers in a track or soft or wet terrain situation.

[0022] According to one embodiment, the second speed threshold is between 3 km / h and 5 km / h. Here too, this speed threshold, in reverse, relatively low, corresponds to parking maneuvers or maneuvers in a track or soft or wet terrain situation.

[0023] Said first and second thresholds may be of the same value or may take different values.

[0024] According to one embodiment, the declaration of a fault of the first type or a fault of the second type or a fault of the third type or a fault of the fourth type or a fault of the fifth type is carried out only if the condition of exceeding the torque deviation above the respective threshold is true for a respective predetermined consecutive duration. Whereby the method avoids reacting to an aberrant value which may be the consequence of the presence of electromagnetic interference; thus certain false fault detections are avoided.

[0025] According to one embodiment, a fault of the first type (FT1) is declared by the first conditional test el if the torque deviation is greater than the first threshold (SCI) for a first predetermined duration (DF1), and / or a fault of the second type (FT2) is declared by the second conditional test e2 if the torque deviation EC is greater than the second threshold (SC2) for a second predetermined duration (DF2), and / or a fault of the third type (FT3) is declared by the third conditional test e3 if the torque deviation is greater than the third threshold (SC3) for a third predetermined duration (DF3), and / or a fault of the fourth type (FT4) is declared by the fourth conditional test e4 if the torque deviation EC is greater than the fourth threshold (SC4) for a fourth predetermined duration (DF4),and / or a fifth type fault (FT5) is declared by the fifth conditional test e5 if the torque deviation is greater than the fifth threshold (SC5) for a fifth predetermined duration (DF5).

[0026] According to one embodiment, the thresholds are calibratable values. This concerns the first speed threshold and the second speed threshold as well as the various torque thresholds, from the first to the fifth. The thresholds can thus be adapted according to the configuration of the powertrain, the nature of the motor tractor unit placed on the front axle, the weight of the vehicle, the current driving mode, or other parameters linked to the vehicle or the circumstances of use of the vehicle.

[0027] According to one embodiment, the torque achieved is calculated according to the formula CR = I x U x RD / W, where RD is an efficiency coefficient from a calibration table, I is the current drawn from the battery by the electric machine, U is the voltage across the terminals of the incident electrical power supply to the electric machine and W is the rotational speed of the rotor. This calculation is based on actual measured current and voltage values, as well as on a measurement of the instantaneous rotational speed. As a result, the achieved torque value CR represents the torque actually delivered by the rotor.

[0028] According to one embodiment, the torque setpoint is determined as a function of a depressing the accelerator pedal and the torque setpoint is transmitted directly or indirectly to a control unit responsible for controlling the electric machine. Note that said torque setpoint can change dynamically and that the torque produced must follow this setpoint as closely as possible.

[0029] According to one embodiment, provision is made, in the event of an interruption in the power supply or in the event of a reset procedure, for a reset of the nominal operation following a reconfiguration. As a result, normal operation is restored in the event of a specific fault occurring in a very specific driving situation. The driver returns to normal behavior; only the memory of the fault and its type will provide a trace for diagnosis and possible repair.

[0030] The invention also relates to a motor vehicle comprising an electric powertrain comprising a first electric machine arranged on the front axle and a second electric machine arranged on the rear axle, the second electric machine being controlled by a local control unit characterized in that the local control unit is configured to implement the method as described previously where the electric machine of interest is the second electric machine.

[0031] The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the appended figures illustrating variants of the invention, in which: [Fig.l] is a schematic representation of a motor vehicle equipped with a traction chain with an electric machine on the rear axle where the method according to the present invention can be implemented; [Fig.2] shows a diagram illustrating the application scenarios of the different conditional tests; [Fig.3] shows a flowchart illustrating an example of the steps involved in the proposed method.

[0032] In the various figures, the same references designate identical or similar elements.

[0033] In [Fig.l], a VHL vehicle is shown schematically in a top view. The VHL vehicle comprises a front axle on the front side AV and a rear axle on the rear side ARR. The powertrain CT comprises a motor-tractor unit with a first electric machine Ml in direct or indirect engagement with the wheel shafts of the front axle. At the front axle, an internal combustion engine MO (also called a heat engine) may be present, in which case it forms, with the first electric machine Ml, a hybrid motor-tractor unit engaged with the front axle.

[0034] The CT drive train comprises a second electric machine M2 in engagement with the wheel shafts of the rear axle.

[0035] A BATT traction battery is provided, which forms a reservoir of electrical energy in electrochemical form.

[0036] A battery management computer 13 (designated by the acronym BMS for “Battery Management System”) is provided, adapted as known to supervise the parameters specific to the battery in cooperation with current and voltage sensors, such as the state of charge SOC (“State of Charge”), the open circuit voltage OCV (“Open Circuit Voltage”), the charging current, the state of health SOH (“State of Health”), or even the temperature of the battery.

[0037] The first electrical machine Ml is controlled by a first control unit 11 via an inverter Invl (or 'inverter' in the jargon of the trade) which comprises power switches connected to the phases of the stator.

[0038] The second electrical machine M2 is controlled by another control unit 12 via an inverter Inv2, similar to the aforementioned inverter.

[0039] The torque setpoint CC is determined as a function of a depression of the accelerator pedal. The accelerator pedal position sensor can be read by the first control unit 11 or by the supervisor computer 14.

[0040] The supervisory computer is responsible for developing the torque instructions which are requested from the front tractor motor unit and from the M2 electric machine of the rear axle.

[0041] In the example illustrated, the various computers marked 11, 12, 131, 14 communicate with each other via a CAN network 15, or by any possible means of communication.

[0042] In the example illustrated, the supervisor computer 14 receives an accelerator pedal depression instruction from the accelerator pedal sensor.

[0043] The supervisor computer 14 receives the VHL speed information via the CAN network (coming from the ESP / AB S computer). The supervisor computer 14 receives the direction of travel information via the gear lever.

[0044] The supervisor computer 14 transforms the information of the pedal depression instruction into a wheel torque instruction (as a function of the speed of the VHL) and the information of the direction of travel into a sign of the torque to be supplied.

[0045] Alternatively, the pedal depression instruction can be translated firstly by the supervisor computer into wheel torque or directly into torque at the output of the electric machine. If the torque is firstly understood as a wheel torque, the supervisor computer only has to divide it by the reduction ratio of the reducer to deduce a torque instruction at the rotor of the electric machine.

[0046] It should be noted that the functional distribution between the computers 11, 12, 14 can be any and different from the distribution set out for the example illustrated in reference to the figures.

[0047] Each electrical machine therefore receives a torque instruction generically noted CC. Furthermore, each electrical machine is configured to measure the actual torque produced on the rotor, the torque produced being noted CR.

[0048] The achieved torque CR is calculated according to the formula CR = I x U x RD / W where RD is an efficiency coefficient from a calibration table.

[0049] I is the current drawn from the battery by the inverter, U is the supply voltage at the inverter terminals. W is the rotation speed of the rotor.

[0050] From the torque setpoint CC and the determination of the torque actually achieved CR, a torque difference noted EC can be deduced according to the following formula.

[0051] EC = ICC-CRI

[0052] Expressed differently, the torque deviation EC is the absolute value of the difference between the torque setpoint CC and the actual torque CR.

[0053] The method which is the subject of the description in the following paragraphs is applicable in particular to the second electric machine M2 arranged on the rear axle. It should however be noted that it is not excluded to apply said method to the first electric machine or to any other electric traction machine on a motor vehicle, the motor vehicle being able to be a leisure vehicle, a passenger vehicle, a utility vehicle, an all-terrain vehicle, a truck, without limitation on the type of vehicle of interest.

[0054] The method provides for a recurrent application of several conditional tests, named e1 to e5 and explained in more detail below.

[0055] el- if the torque setpoint CC is zero, then a first torque threshold SCI is used, also called for brevity first threshold SCI. If the torque deviation EC is greater than SCI for a first duration DF1, while the torque setpoint remains zero, then a fault of a first type FT1 is declared by the method.

[0056] If the torque difference EC remains lower than SCI, or exceeds SCI but for a duration shorter than the first duration DF1, then there is no generation of a fault of a first type FT1.

[0057] In [Fig.2], the diagram illustrates the different scenarios for applying the different conditional tests e1, e2, e3, e4, e5. In [Fig.2], the zero torque setpoint zone is indicated by the circled number 1.

[0058] If the torque setpoint CC is non-zero, we move on to other tests based on the instantaneous speed VV of movement of the vehicle and the instantaneous direction of movement of the vehicle (direction of travel) among the forward gear MAV and the reverse gear MAR.

[0059] It should be noted that the instantaneous speed VV of movement of the vehicle corresponds to an average speed corresponding to the speed of the wheels monitored by the cal- ABS actuator.

[0060] A first speed threshold denoted SVHLpos relating to the forward movement speed is provided, and a second speed threshold denoted SVHLneg relating to the backward movement speed.

[0061] e2- if the DC torque setpoint is non-zero, if the instantaneous direction of de vehicle placement is forward gear MAV and if the instantaneous vehicle movement speed VV is lower than the first speed threshold SVHLpos, then a second torque threshold SC2 is used, also called for brevity second threshold SC2,

[0062] If the torque deviation EC is greater than SC2 for a second duration DF2, while the torque setpoint remains non-zero and the speed VV remains lower than SVHLpos, then a fault of a second type FT2 is declared by the method.

[0063] If the torque difference EC remains lower than SC2, or exceeds SC2 but for a duration shorter than the second duration DF2, then there is no generation of a fault of a second type FT2.

[0064] In [Fig.2], the operating zones in the forward direction MAV are identified by the circled numbers 2 and 3.

[0065] e3- if the torque setpoint is non-zero, if the instantaneous direction of movement of the vehicle is the forward gear MAV and if the instantaneous speed of movement of the vehicle is greater than the first speed threshold SVHLpos, then a third torque threshold SC3 is used, also called for brevity the third threshold SC3.

[0066] If the torque deviation EC is greater than SC3 for a third duration DF3, while the torque setpoint remains non-zero and the speed VV remains greater than SVHLpos, then a fault of a third type FT3 is declared by the method.

[0067] If the torque deviation EC remains lower than SC3, or exceeds SC3 but for a duration shorter than the third duration DF3, then there is no generation of a fault of a third type FT3.

[0068] e4- if the DC torque setpoint is non-zero, if the instantaneous direction of de vehicle placement is reverse gear MAR and if the instantaneous vehicle movement speed VV is lower than the second speed threshold SVHLneg, then a fourth torque threshold SC4 is used, also called for brevity the fourth threshold SC4,

[0069] If the torque deviation EC is greater than SC4 for a fourth duration DF4, while the torque setpoint remains non-zero and the speed VV remains lower than SVHLneg, then a fault of a fourth type FT4 is declared by the method.

[0070] If the torque deviation EC remains lower than SC4, or exceeds SC4 but for a duration lower than the fourth duration DF4, then there is no generation of a fault of a fourth type FT4.

[0071] e5- if the torque setpoint is non-zero, if the instantaneous direction of movement of the vehicle is reverse gear MAR and if the instantaneous speed of movement of the vehicle is greater than the second speed threshold SVHLneg, then a fifth torque threshold SC5 is used, also called for brevity the fifth threshold SC5.

[0072] If the torque deviation EC is greater than SC5 for a fifth duration DF5, while the torque setpoint remains non-zero and the speed VV remains greater than SVHLneg, then a fault of a fifth type FT5 is declared by the method.

[0073] If the torque deviation EC remains lower than SC5, or exceeds SC5 but for a duration lower than the fifth duration DF5, then there is no generation of a fault of a fifth type FT5.

[0074] In [Fig.2], the operating zones in the reverse direction MAR are marked by the numbers 4 and 5 circled.

[0075] [Fig.3] illustrates two flowcharts, in the top right part marked 3B, it is the task marked 6 which continuously calculates the torque difference EC, as a function of the instantaneous current consumed I, the voltage U at the terminals of the inverter, the rotation speed W of the rotor and the efficiency coefficient RD read in a calibration table 60. The values ​​of the efficiency coefficient RD in the calibration table represent the intrinsic performance of the motor and said table is established in advance during qualification tests of the motor (i.e. of the electrical machine).

[0076] In the main part at the bottom left marked 3A of [Fig.3], this is the test logic loop exposed in the previous paragraphs.

[0077] On the test flowchart, we see, starting from the left going towards the right, the branch of the first test el which can give the declaration of a fault of the first type FT1, then the branch of the second test e2 which can give the declaration of a fault of the second type FT2, then the branch of the third test e3 which can give the declaration of a fault of the third type FT3, then the branch of the fourth test e4 which can give the declaration of a fault of the fourth type FT4, and finally the branch of the fifth test e5 which can give the declaration of a fault of the fifth type FT5.

[0078] In [Fig.3], the test marked DirD corresponds to the determination of the direction of travel MAV or MAR.

[0079] The periodicity of repetition of steps e1 to e5 is rapid, the corresponding task has high recurrence, for example every 10 milliseconds.

[0080] Fault counters may be provided for each type of fault, in order to implement the conditions for the duration of presence of each fault. Each counter is incremented in the event of a fault and decremented in the event of the absence of a fault. If the counter reaches a predefined high threshold, then the fault is declared and stored in non-volatile memory.

[0081] The duration values ​​DF1, DF2, DF3, DF4 and DF5 are calibration parameters, in other words calibratable parameters. The possible values ​​can range from 5 ms to 800 ms. Preferably, values ​​between 300 ms and 600 ms can be chosen.

[0082] The five duration values ​​can be differentiated. According to a particular variant, the 5 values ​​can be identical.

[0083] The duration values ​​SCI, SC2, SC3, SC4 and SC5 are calibration parameters, in other words calibratable parameters.

[0084] Concerning SCI, a value of 1 Nm to 2 Nm can be chosen.

[0085] Regarding SC2 and SC4, values ​​ranging from 30 Nm to 80 Nm can be chosen. Preferably, the values ​​can be chosen in an interval between 40 Nm and 65 Nm. The values ​​of SC2 and SC4 can be differentiated. According to a particular variant, the values ​​of SC2 and SC4 can be identical.

[0086] Regarding SC3 and SC5, values ​​ranging from 50 Nm to 120 Nm can be chosen. Preferably, the values ​​can be chosen in an interval between 70 Nm and 100 Nm. The values ​​of SC3 and SC5 can be differentiated. According to a particular variant, the values ​​of SC3 and SC5 can be identical.

[0087] It is noted that the values ​​of SC3 and SC5 are significantly higher than the values ​​of SC2 and SC4. This materializes the relaxation of the precision constraints required for speeds beyond the thresholds SVHLpos and SVHLneg, respectively for forward and reverse travel.

[0088] The first speed threshold SVHLpos can be chosen between 3 km / h and 5 km / h. The second speed threshold SVHLneg can be chosen between 3 km / h and 5 km / h. If the vehicle speed information is signed, then the second speed threshold can be expressed in negative values, i.e. -3 km / h to -5 km / h.

[0089] The method provides for a reconfiguration of the electrical machine in the event of declaration of a first type fault FT1 or a second type fault FT2 or a third type fault FT3 or a fourth type fault FT4 or a fifth type fault FT5.

[0090] There may be one or more types of reconfiguration (RCFG in [Fig.3]), i.e. one or more levels of reconfiguration depending on the nature of the fault.

[0091] . A reconfiguration corresponds to a switch to degraded mode or an inhibition total or partial delivery of torque.

[0092] If the electric machine comes in addition to a main motor tractor group, the reconfiguration may consist of completely inhibiting the delivery of torque, otherwise a particular protection mode may be provided, e.g. a so-called 'limp home' mode so as not to completely stop the delivery of torque.

[0093] In the event of an interruption in the power supply (at the end of the driving cycle), provision is made for a reset of the nominal operation following a reconfiguration. driver returns to normal behavior, only the memory of the reported fault and its type will allow a trace to be kept for diagnosis and possible repair.

[0094] The fault information may be stored in a memory of the local control unit 12 or in a memory area of ​​the supervisor 14.

Claims

Claims

1. Method for monitoring the engine torque of an electric machine of an axle of a traction chain (CT) for an electrified vehicle, the method comprising the determination of a torque difference (EC) between a torque setpoint (CC) transmitted to the electric machine and a torque produced (CR) by the rotor of the electric machine (M2), the method providing for an acquisition of an instantaneous speed (VV) of movement of the vehicle and an instantaneous direction of movement of the vehicle among forward gear (MAV) and reverse gear (MAR), characterized in that the method provides for a recurrent application of the following logic: el- if the torque setpoint (CC) is zero, then declare a fault of a first type (FT1) if the torque deviation EC is greater than a first threshold (SCI), e2- if the torque setpoint (CC) is non-zero, if the instantaneous direction of movement of the vehicle is forward and if the instantaneous speed of movement of the vehicle (VV) is less than a first speed threshold (SVHLpos), then declare a fault of a second type (FT2) if the torque deviation is greater than a second threshold (SC2), e3- if the torque setpoint is non-zero, if the instantaneous direction of movement of the vehicle is forward and if the instantaneous speed of movement of the vehicle (VV) is greater than the first speed threshold (SVHLpos), then declare a fault of a third type if the torque deviation is greater than a third threshold (SC3), e4- if the torque setpoint is non-zero,if the instantaneous direction of movement of the vehicle is reverse and if the instantaneous speed of movement of the vehicle (VV) is less than a second speed threshold (SVHLneg), then declare a fault of a fourth type if the torque difference is greater than a fourth threshold (SC4), e5- if the torque setpoint is non-zero, if the instantaneous direction of movement of the vehicle is reverse and if the instantaneous speed of movement of the vehicle (VV) is greater than the second speed threshold (SVHLneg), then declare a fault of a fifth type if the torque difference is greater than a fifth threshold (SC5).,

2. Method according to claim 1, characterized in that the method provides for a reconfiguration of the electrical machine in the event of declaration of a first type fault (FT1) or a second type fault type (FT2) or a third type defect (FT3) or a fourth type defect (FT4) or a fifth type defect (FT5).

3. Method according to any one of claims 1 to 2, characterized in that the first speed threshold (SVHLpos) is between 3 km / h and 5 km / h.

4. Method according to any one of claims 1 to 3, characterized in that the second speed threshold (SVHLneg) is between 3 km / h and 5 km / h.

5. Method according to any one of claims 1 to 4, characterized in that the declaration of a fault of the first type (FT1) or a fault of the second type (FT2) or a fault of the third type (FT3) or a fault of the fourth type (FT4) or a fault of the fifth type (FT5) is carried out only if the condition of exceeding the torque deviation above the respective threshold is true for a respective predetermined consecutive duration (DF1, DF2, DF3, DF4, DF5).

6. Method according to any one of claims 1 to 5, characterized in that the thresholds are calibratable values.

7. Method according to any one of claims 1 to 6, characterized in that the torque achieved (CR) is calculated according to the formula CR = I x U x RD / W, where RD is an efficiency coefficient from a calibration table, I is the current drawn from the battery by the electric machine, U is the voltage across the terminals of the incident electric machine power supply and W is the rotation speed of the rotor.

8. Method according to any one of claims 1 to 7, characterized in that the torque setpoint (CC) is determined as a function of a depression of the accelerator pedal and the torque setpoint is transmitted directly or indirectly to a control unit (12) responsible for controlling the electric machine.

9. Method according to any one of claims 1 to 8, characterized in that provision is made, in the event of an interruption in the power supply or in the event of a reset procedure, for a reset of the nominal operation following a reconfiguration.

10. Motor vehicle comprising an electric powertrain (CT) comprising a first electric machine (Ml) arranged on the front axle and a second electric machine (M2) arranged on the rear axle, the second electric machine being controlled by a local control unit (12) characterized in that the local control unit is configured to implement the method according to one of the re- claims 1 to 9 where the electric machine of interest is the second electric machine (M2).

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