WO2023233085A1

WO2023233085A1 - Method for controlling an electric machine, and corresponding computer program product and vehicle

Info

Publication number: WO2023233085A1
Application number: PCT/FR2023/050365
Authority: WO
Inventors: Olivier BALENGHIEN
Original assignee: Stellantis Auto Sas
Priority date: 2022-05-31
Filing date: 2023-03-16
Publication date: 2023-12-07
Also published as: FR3135943A1; FR3135943B1

Abstract

The invention relates to a method for controlling an electric machine in a vehicle having an electric drive chain, the method comprising: a step (E200) of determining, using the first computer, a torque gradient deviation between a setpoint torque gradient and a torque gradient achieved for the same given periodicity; a step (E210) of comparing the torque gradient deviation with a maximum permissible acceptability threshold; a step (E220) of reconfiguring the electric machine, including cutting off the power supply to the electric machine; and a step of restoring the power supply to the electric machine, according to one of three options (E230, E240, E250). The invention further relates to a computer program product and a motor vehicle which are suitable for implementing the method.

Description

DESCRIPTION

TITLE OF THE INVENTION: METHOD FOR CONTROLLING AN ELECTRIC MACHINE, CORRESPONDING COMPUTER PROGRAM PRODUCT AND VEHICLE

The present invention claims the priority of French application No. 2205183 filed on 05.31.2022, the content of which (text, drawings and claims) is here incorporated by reference.

The present invention generally relates to vehicles having an electric traction chain, that is to say driven by an electric traction machine. In particular, the invention relates to the field of controlling the electric traction machine, in particular during a phase of depression of the accelerator or braking pedal by the driver.

Such an electric powertrain vehicle is illustrated schematically in Fig. 1. In this figure, the vehicle 5 comprises an electric traction chain 6. The electric traction chain 6 comprises a battery 8 forming an energy source, a set of computers 9, an electric machine 10, a transmission 11, drive wheels 12 and an inverter 13. The assembly formed by the computers 9, the electric machine 10, the transmission 11, the driving wheels 12 and an inverter 13 is called the powertrain 7. The computers 14, 15, 16, 17 and 18 of the set of calculators 9 include for example, without limitation:

> the eVCU 14 (or Electric Vehicle Control Unit), which is the general supervisor of the powertrain, that is to say the central computer. As such, the eVCU coordinates, controls, controls and supervises the computers of the eCAN bus communication system (from the English “Electrical Controller Area Network”). The computers of the eCAN bus communication system are for example the MCU 15 described below, the BMS 16 (Battery Management System), the OBCDC 17 (On board Charger Direct Current), the ePLU 18 (electrical Park Lock Unit), an ESP/ABS 19 calculator (ESP: “Electronic Stability Program”; ABS: Anti-Block Safety ) ; > the MCU 15 (or Machine Control Unit), which is the computer of the electrical machine 10 and, as such, manages the operation of the electrical machine 10.

The electric machine 10 is for example an electric machine of known type such as the permanent magnet synchronous machine 10 illustrated in FIG. 2. This has a stator 21 and a rotor 22. The stator 21 is here provided with 3 coils 21a, 21 b and 21c forming 3 poles of the electrical machine 10. The rotor 22 has an axis 23, movable in rotation, and a permanent magnet 24, mounted on the axis 23. The permanent magnet 24 is here provided with a negative pole 25 and a positive pole 26.

The permanent magnet synchronous electric machine 10, in its motor mode, operates with pulses. These pulses are obtained by the coils 21 a, 21 b and 21 c arranged around the periphery of the stator 21. These coils 21 a, 21 b and 21 c are also called the poles of the electric machine. When current i _a , ib and i _c (represented here in a purely illustrative sense) are passed through the coils 21a, 21 b and 21c, a magnetic field is generated by these and the coils 21a, 21 b and 21c then behave like magnets whose arrangement of the poles depends on the direction of the current.

An electric machine such as the electric machine 10, when used in a vehicle such as the vehicle 5, can operate as a motor, in which case the electric machine provides a driving torque to the drive wheels 12 by conversion by the inverter 13 of the electrical energy stored in the battery 8, or as a generator, in which case the electric machine brakes the traction chain 6 in order to transform part of the mechanical torque into electrical energy and thus recharge the battery 8 via of the inverter 13.

A bidirectional speed sensor (not shown) is then placed at the electrical machine output 10. It is thanks to this bidirectional speed sensor that the MCU 15 and/or the eVCU 14 determine the torque at the electrical machine output.

The electric machine 10 receives electric power Pelec at its input terminals from the high voltage circuit of the vehicle 5: Pelec = U x I; with Pelec which is the electrical power at the input of the electrical machine 10, U, the voltage across the terminals of the electrical machine 10 at the output of the high circuit voltage, and, I, the current at the terminals of the electric machine 10 at the output of the high voltage circuit.

The electric machine 10 supplies mechanical power Pméca to the traction chain 6 of the vehicle 5: Pméca = C x W; with Pméca which is the mechanical power output from the electrical machine 10, C, the torque output from the electrical machine 10, and, W, the rotational speed of the rotor 22 of the electrical machine 10.

Furthermore, Pméca = Pélec x p; with p which is the efficiency coefficient of the electric machine 10, as measured on the bench for each step of speed, of torque, for each step of voltage, for each step of supply current of the electric machine 10 (or in variant for each step of supply current of the poles 21a, 21 b, 21c of the stator 21 of the electric machine 10) and for each step of stator temperature 21. The mapping of p values is learned on the electrical machine component bench and stored in the MCU memory.

Since Pméca = Pélec x p, it follows that C x W = U x I x p, therefore that C = U x I x p / W

So the MCU 15 measures or receives information about the voltage across the terminals of the electrical machine 10; the MCU 15 measures or receives information about the current drawn by the electrical machine 10; the MCU 15 measures or receives information about the rotation speed of the rotor of the electric machine 10.

The MCU 15 deduces the efficiency coefficient p thanks to the rotor rotation speed 22 of the electric machine 10, the temperature of the stator 21, the current drawn by the electric machine 10 and the voltage at the terminals of the electric machine 10.

And thus, the MCU 15 calculates the torque that the electric machine 10 provides to the traction chain by the formula C = U x l x p / W.

Today, during acceleration phases, the eVCU 14 receives a setpoint signal coming from the depressing of the accelerator pedal, and the eVCU 14 in turn sends an engine torque setpoint to the electric machine 10 (for acceleration).

In the braking phase, when the driver presses the brake pedal, the ESP/ABS 19 computer receives hydraulic pressure measurement information linked to the level of depression of the brake pedal (not shown). The ESP/ABS then determines the portion of braking torque to be produced by the brake discs (not shown) (by dissipative braking) and the portion of braking torque to be produced by the electric machine 10 (by regenerative braking). The ESP/ABS thus sends the level of regenerative braking torque to be generated in the electric machine 10 to the powertrain supervisor 7 (the eVCU 14). The eVCU 14 then checks the feasibility of this regenerative braking torque instruction, and, if it is achievable, the eVCU 14 then sends this regenerative braking torque instruction to the electric machine 10.

In certain cases, the electrical machine 10 may be slow to react. When it then reacted, the driver was able to continue pressing either pedal. Thus, when the electric machine 10 reacts with a delay, it must compensate for a large torque difference. The electric machine 10 can thus begin to accelerate more quickly than the gradient of depression of the accelerator pedal, or to brake more strongly than the regenerative braking torque setpoint, that is to say to react with a magnitude greater than the actual desire for acceleration or braking expressed by the driver. The vehicle may then experience sudden acceleration or braking. The occupants may then feel the vehicle jerking and comfort may be affected.

An objective of the invention is therefore to propose a method of controlling an electric machine forming a drive motor, in a vehicle with an electric drive chain, respecting in a more reliable manner the driver's acceleration or braking instructions. , notably less subject to possible jolts than in existing technologies. The invention further aims to propose a computer program product capable of implementing the aforementioned control method and a vehicle with an electric drive chain in which this control method is implemented.

To achieve this objective, the invention proposes a method of controlling an electric machine forming a drive motor and an electric generator, in a vehicle with an electric drive chain, the vehicle comprising:

- a battery forming a source of electricity; - a powertrain comprising the electric machine, at least one driving wheel, at least one set of computers, and an inverter arranged between the battery and the electric machine, the electric machine being supplied with current from the battery via the inverter, and configured to convert the electricity received from the battery via the inverter into mechanical energy in a motor mode, and to convert the mechanical energy received into electricity in a generator mode, the electric machine further comprising a stator , having a plurality of poles, and a rotor; the at least one drive wheel being configured to be rotated by the mechanical energy produced by the electrical machine; the set of calculators comprising:

- a first computer, called a machine control unit, and forming a control member of the electric machine;

- a central computer, called an electric vehicle control unit, and forming a general supervisor of the powertrain, including the first computer; the method of controlling the electrical machine comprising:

- a step of sending a torque reference to the first computer by the central computer;

- a step of transmitting a current setpoint to the inverter by the first computer;

- a step of measuring, or receiving the measurement, by the first calculator

-- the voltage at the terminals of the electrical machine;

-- the current drawn by the electrical machine;

-- the temperature of the stator of the electric machine; And

-- the rotational speed of the rotor of the electric machine;

- a step of determining an efficiency coefficient of the electric machine using the voltage at the terminals of the electric machine, the current drawn by the electric machine and the rotation speed of the rotor of the electric machine;

- a step of calculating the torque produced that the electric machine produces for the drive wheel; - a step of calculating the target torque gradient according to a periodicity given by the first calculator;

- a step of calculating the torque gradient produced according to the periodicity given by the first calculator;

- a step of determining a torque gradient difference between the set torque gradient and the torque gradient produced for each periodicity given by the first calculator;

- a step of comparing the torque gradient deviation with a maximum acceptability threshold corresponding to a maximum admissible torque gradient deviation, by the first calculator;

- a step of reconfiguring the electrical machine, by the first computer, triggered when the difference in torque gradient exceeds the acceptability threshold for a duration greater than a predetermined analysis duration, the reconfiguration step including a cut-off the power supply of the electrical machine;

- a step of restoring power to the electrical machine.

The method according to the invention thus advantageously makes it possible to take into account a requirement to respect the effective driving or braking torque gradient with respect to the driving or braking torque setpoint received by the electric machine and coming from eVCU. Taking into account the torque gradient thus makes it possible to improve the dosability of the accelerator pedal and the brake pedal with respect to the torque setpoint received by the electric machine from the eVCU. Thus, the electric machine is not content to simply follow the torque instruction with the risk of random reaction times. The introduction of a requirement to respect a torque gradient to be respected makes it possible to comply more reliably with the driver's desire for acceleration or braking. The invention thus limits jerks in acceleration and braking, and the discomfort of vehicle occupants which may result therefrom.

Advantageously, the step of reconfiguring the electrical machine can be triggered when:

- in a motor mode of the electric machine, the first calculator determines that the torque gradient difference exceeds a first threshold acceptability for a duration greater than or equal to a first analysis duration; Or,

- in a generator mode of the electric machine, the first calculator determines that the difference in torque gradient exceeds a second acceptability threshold for a duration greater than or equal to a second analysis duration; the first acceptability threshold and the second acceptability threshold preferably being different from each other.

Advantageously, the first acceptability threshold and the second acceptability threshold can be calibrated independently of each other.

Advantageously:

- the first acceptability threshold can be between 5 and 50 Nm/s, preferably between 10 and 35 Nm/s, more preferably equal to 25 Nm/s; and or,

- the second acceptability threshold can be between 3 and 30 Nm/s, preferably between 5 and 20 Nm/s, more preferably equal to 10 Nm/s.

Advantageously:

- said periodicity can be chosen between 10 and 200 ms, preferably between 25 and 100 ms, more preferably between 40 and 75 ms; and or

- the first analysis duration and/or the second analysis duration may be between 50 and 1000 milliseconds, preferably between 100 and 500 milliseconds, more preferably may be equal to one and/or the other at 200 milliseconds.

Advantageously, the step of reconfiguring the electrical machine can include cutting off the HV power supply to the electrical machine.

Advantageously, according to a first option, the restoration step can prohibit any restoration of the HV power supply to the electric machine by restarting the vehicle and any restoration of the HV power supply to the electric machine by the vehicle itself.

Advantageously, according to a second option, the restoration step can authorize restoration of power to the electrical machine by restarting the vehicle.

Advantageously, according to a third option, the restoration step can prohibit any restoration of the HV power supply to the electrical machine by restarting the vehicle and by the vehicle itself when the first calculator has determined that the torque gradient deviation has exceeded a first acceptability threshold for a duration greater than or equal to a first analysis duration in a motor mode of the electric machine, and, the recovery step can authorize restoring power to the electric machine by restarting the vehicle when the first computer has determined that the torque gradient difference has exceeded a second acceptability threshold for a duration greater than or equal to a second analysis duration in a generator mode of the electric machine.

The invention further relates to a computer program product capable of implementing the method of controlling an electric machine forming a drive motor.

The invention also relates to a vehicle with an electric drive chain, configured to be able to implement the aforementioned control method and/or in which the aforementioned computer program product is installed.

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.1] schematically illustrates a vehicle comprising an electric traction chain having a battery and a powertrain comprising a set of computers, an electric machine, a transmission, a drive wheel and an inverter;

- [Fig.2] illustrates a synchronous electric machine with permanent magnet and three phases, as an example of an electric traction machine of the present invention;

- [Fig.3] illustrates a flowchart detailing examples of steps in an electrical machine control process.

DETAILED DESCRIPTION

The invention is now described by way of example with reference to the electric machine 10 mentioned in the preamble, that is to say in an electric machine with a permanent magnet having three poles, implemented in the vehicle 5 mentioned in the preamble , illustrated schematically respectively in Figs. 1 and 2. The steps of the method according to the invention are referenced with reference to FIG. 3 and are designated by a quadrigram starting with the letter E (e.g.: E130, E140, etc.)

In a step E100 of obtaining pedal depression measurement information:

During an acceleration phase, the powertrain supervisor 7 (the eVCU 14) receives information measuring the depression of the accelerator pedal from the accelerator pedal sensor (not shown (E100) ;

_ By analogy, during a braking phase, when the driver presses the brake pedal, the ESP/ABS 19 computer receives hydraulic pressure measurement information linked to the level of depression of the brake pedal ( not shown).

The eVCU 14 receives vehicle speed information via the CAN (Controller Area Network), or eCAN, from the ESP/ABS computer (step E110).

In a step E120 of transforming pedal depression measurement information into torque setpoint:

> in the acceleration phase (electric machine 10 operating in motor mode), the eVCU 14 transforms the information from the measurement of depression of the accelerator pedal into the drive torque setpoint for the wheel 12 as a function of the speed of the vehicle 5. Alternatively, the measurement of depression of the accelerator pedal can be translated directly into a torque setpoint to be provided at the output of the electric machine 10. If the torque is firstly understood as a torque at the wheel, the eVCU 14 applies a reduction coefficient of the reduction gear to deduce a drive torque setpoint to the rotor 22 of the electric machine 10; in the braking phase (electric machine 10 operating in generator mode), the ESP/ABS 19 computer then determines the portion of the braking torque to be produced by the brake discs (not shown) (by dissipative braking) and the portion of braking torque to be produced by the electric machine 10 (by regenerative braking). The ESP/ABS thus sends the level of regenerative braking torque to be generated in the electric machine 10 to the powertrain supervisor 7 (the eVCU 14). The eVCU 14 then checks the feasibility of this regenerative braking torque instruction, and, if it is achievable, the eVCU 14 then sends this regenerative braking torque instruction to the electric machine 10.

Thus, a torque setpoint Ce is obtained in step E120, this concept covering the drive torque setpoint at the wheel 12 or rotor 22 (motor mode of the electric machine 10), and the braking torque setpoint regenerative to the electric machine 10 (generator mode), depending on the driving situation.

The eVCU 14 sends the torque instruction Ce, which the electric machine 10 must provide, to the MCU 15 (step E130).

The MCU 15 also has a correspondence map which allows it to know the quantity of current that the inverter 13 must draw from the high voltage network of the vehicle 5 to offer this requested torque as a function of the voltage of the high voltage network and of the temperature of the stator 21 of the electric machine 10.

The inverter 13 of the electric machine 10 draws current from the high voltage network of the vehicle 5 and supplies two of the three poles 21a, 21 b and 21c of the electric machine 10 as a function of the position of the rotor 22.

The MCU 15 then receives the torque instruction Ce from the eVCU 14.

The MCU 15 transmits a current setpoint to the inverter 13 (step E140), which the latter must take from the high voltage network of the vehicle 5 to supply, in turn, two of the three poles 21a, 21 b and 21 c of the stator 21 of the electric machine 10.

In a following step (E150), the MCU 15 then measures or receives information about the voltage U across the terminals of the electrical machine 10; the MCU 15 measures or receives information about the current I taken by the electrical machine 10; the MCU 15 measures or receives information about the rotation speed a) of the rotor of the electric machine 10.

The MCU 15 then determines the efficiency coefficient p (step E160) thanks to the rotor rotation speed 22 of the electric machine 10, the temperature of the stator 21, the current drawn by the electric machine 10 and the voltage across the terminals of the electric machine 10. Then, the MCU 15 calculates the realized torque Cr (step E170) that the electric machine 10 supplies to the traction chain 6 (in motor mode), or generates (in generator mode) by the formula C = U xlxp / W.

The MCU 15 then calculates the target torque gradient GCc (step E180) at a periodicity Dt which can be calibrated when setting up the function. The formula for calculating the setpoint torque gradient GCc is as follows:

GCc = (Cc(t+Dt) - Cc(t))/Dt

The MCU 15 calculates in the same way the torque gradient produced GCr (step E190) according to the same periodicity as the calculation of the target torque gradient GCc. The formula for calculating the torque gradient achieved GCr is as follows:

GCr = (Cr(t+Dt) - Cr(t))/Dt

The MCU 15 then executes a step of determining a torque gradient difference EGC (step E200) between the set torque gradient GCc requested by the eVCU and the torque gradient produced GCr at the output of the electrical machine 10. formula for determining the torque gradient difference EGC is as follows: EGC = abs(GCr - GCc), for each period Dt which is a calibrated parameter; with abs the absolute value operator.

Two criteria, or thresholds, of acceptability can then be applied:

• CCTrac: threshold of acceptability of the deviation of the torque gradient EGC in traction mode of the electric machine 10;

• CCRégé: acceptability threshold of the EGC torque gradient difference in regenerative mode of the electric machine 10.

Thus, if the electric machine 10 operates in motor (or traction) mode, the MCU 15 compares the torque gradient difference EGC to the CCTrac criterion. And if the electric machine 10 is in generator (or regenerative) mode, the MCU 15 compares the torque gradient difference EGC to the CCrégé criterion.

If EGC is lower than CCTrac in traction mode or CCrégé in alternator mode, everything is compliant, i.e. no failure is noted.

However :

• If the electric machine 10 operates in motor mode and the MCU 15 finds that the torque gradient difference EGC is greater than the acceptability threshold CCTrac for a duration greater than or equal to a first analysis duration D1, then the MCU 15 and the eVCU 14 initiate a step of reconfiguring the electrical machine 10 (step E220 below),

• If the electric machine 10 operates in alternator mode and the MCU 15 finds that the torque gradient difference EGC is greater than the acceptability threshold CCrégé for a duration greater than or equal to a second analysis duration D2, then the MCU 15 and the eVCU 14 initiate a reconfiguration of the electrical machine 10 (step E220 below).

Preferably:

- the first CCTrac acceptability threshold is between 5 and 50 Nm/s, preferably between 10 and 35 Nm/s, more preferably equal to 25 Nm/s; and or,

- the second acceptability threshold CCRégé is between 3 and 30 Nm/s, preferably between 5 and 20 Nm/s, more preferably equal to 10 Nm/s.

Also preferably:

- said periodicity Dt is chosen between 10 and 200 ms, preferably between 25 and 100 ms, more preferably between 40 and 75 ms; and or

- the first analysis duration D1 and/or the second analysis duration D2 is/are between 50 and 1000 milliseconds, preferably between 100 and 500 milliseconds, more preferably is/are equal to one and/or the other at 200 milliseconds.

The previously mentioned reconfiguration step (E220) includes for example some of the following aspects:

- the MCU 15 can memorize a fault code in its read-only memory (not shown) and communicates it to the eVCU 14, to indicate to the after-sales service that the MCU 15 has encountered a problem of non-compliance with the instruction of the torque gradient of the electric machine 10. Alternatively, a first fault code is defined for a problem of non-compliance with the torque gradient setpoint in motor mode and a second fault code is defined for a problem of non-compliance -compliance with the torque gradient setpoint in alternator mode of the electric machine 10;

- the MCU 15 can ask the eVCU 14 to turn on a warning light (STOP) on a dashboard (not shown) of the vehicle 5, and a message on the dashboard to indicate to the users of the vehicle 5 that a torque gradient problem has occurred on drive chain 6.

- the MCU 15 cuts the HV power supply to the electrical machine 10. Once the reconfiguration step (E220) has been executed, a recovery step is initiated in one of three possible options E230, E240 or 250.

According to a first option, it is possible that the seriousness of the non-compliance with the torque gradient GCc instruction is so serious that recovery can only be desired by erasing the read-only memory of the MCU 15 by the management teams. after-sales and verification of the electrical machine 10 (or even by changing the electrical machine 10 by the after-sales teams). In other words, the restoration step E230 prohibits any restoration of the power supply to the electric machine 10 by restarting the vehicle 5 and any restoration of the power supply to the electric machine 10 by the vehicle 5 itself (step E230).

According to a second option, it is possible that when the vehicle's ignition is turned off, the fault is automatically rehabilitated and that the vehicle 5 is then authorized to leave once the fault has been rehabilitated. The restoration step E240 therefore authorizes the return of power to the electrical machine 10 by restarting the vehicle 5.

According to a third option, it is possible that in the event of non-compliance with the torque gradient instruction GCc in engine mode, the MCU 15 prohibits restoration without intervention from the after-sales teams. And that in alternator mode, non-compliance with the torque setpoint GCc is restored when the contact of vehicle 5 is switched off, the fault is rehabilitated and vehicle 5 is authorized to leave once the fault has been rehabilitated. In other words, according to this third option (step E250): either the restoration step prohibits any restoration of power to the electrical machine (10) by restarting the vehicle (5) and by the vehicle (5) -even when the first calculator (15) has determined that the torque gradient deviation (EGC) has exceeded a first acceptability threshold (CCTrac) for a duration greater than or equal to a first analysis duration (D1) in a motor mode of the electric machine (10), and, the restoration step authorizes restoration of the power supply to the electric machine (10) by restarting the vehicle (5) when the first computer (15) has determined that the The torque gradient deviation (EGC) has exceeded a second acceptability threshold (CCRégé) for a duration greater than or equal to a second analysis duration (D2) in a generator mode of the electric machine (10) (E250).

Recovery can be reflected in the following aspects:

- the MCU 15 can stop requesting the illumination of the warning light and the message on the dashboard;

- the MCU 15 reauthorizes the operation of the electrical machine 10.

Furthermore, the only thing that can remain, after power has been restored to the electrical machine, from this transition to reconfiguration mode is that the fault code remains stored in the read-only memory of the eVCU 14 and the MCU 15. so that after-sales service can see that the electrical machine 10 has suffered too great a torque gradient. This fault code is then in the “fugitive” state to indicate to after-sales that the fault has been resolved.

The invention is described by way of non-limiting example with reference to the vehicle 5 mentioned in the preamble and/or to the electric machine 10 mentioned in the preamble, that is to say an electric machine with a permanent magnet having three poles, but can also be applied with reference to an electrical machine having a different number of poles, for example six, nine or more than nine poles.

Generally speaking, the invention can be transposed to any vehicle having an electric traction machine, for example, without limitation, electric, hybrid or combustion cell vehicles. These vehicles can be private or commercial vehicles (automobile, motorcycles, scooters, boats, planes, trucks, etc.).

Claims

1. Method for controlling an electric machine forming a drive motor and electric generator, in a vehicle with an electric drive chain (6), the vehicle (5) comprising:

- a battery (8) forming a source of electricity;

- a powertrain (7) comprising the electric machine (10), at least one driving wheel (12), at least one set of computers (9), and, an inverter (13) arranged between the battery (8) and the electric machine (10), the electric machine (10) being supplied with current from the battery (8) via the inverter (13), and configured to convert the electricity received from the battery (8) via the the inverter (13) into mechanical energy in a motor mode of the electric machine (10), and to convert the mechanical energy received into electricity in a generator mode of the electric machine (10), the electric machine further comprising a stator (21), having a plurality of poles (21a, 21b, 21c), and a rotor (22); the at least one driving wheel (12) being configured to be rotated by the mechanical energy produced by the electric machine (10); the set of computers (9) comprising:

- a first computer (15), called a machine control unit, and forming a control member of the electric machine (10);

- a central computer (14), called an electric vehicle control unit, and forming a general supervisor of the powertrain (7), including the first computer (15); the method of controlling the electrical machine (10) comprising:

- a step of sending (E130) a torque reference to the first computer (15) by the central computer (14);

- a step of transmitting (E140) a current setpoint to the inverter (13) by the first computer (15);

- a step of measuring, or receiving the measurement, (E150) by the first calculator (15):

-- the voltage at the terminals of the electric machine (10);

-- the current drawn by the electric machine (10); -- the temperature of the stator of the electric machine (10); and -- the rotation speed of the rotor of the electric machine (10);

- a step of determining an efficiency coefficient (E160) of the electric machine (10) using the voltage at the terminals of the electric machine (10), the current drawn by the electric machine (10) and the rotation speed of the rotor of the electric machine (10);

- a step of calculating the torque produced (E170) that the electric machine produces for the drive wheel (12);

- a step of calculating the target torque gradient (E180) according to a periodicity given by the first calculator (15);

- a step of calculating the torque gradient produced (E190) according to the periodicity given by the first calculator (15);

- a step of determining a torque gradient difference (E200) between the set torque gradient and the torque gradient produced for each periodicity given by the first calculator (15);

- a step of comparing (E210) the torque gradient difference with a maximum acceptability threshold corresponding to a maximum admissible torque gradient difference, by the first calculator (15);

- a step of reconfiguration (E220) of the electrical machine (10), by the first computer (15), triggered when the difference in torque gradient exceeds the acceptability threshold for a duration greater than a predetermined analysis duration , the reconfiguration step including cutting off the power supply to the electrical machine (10);

- a restoration step (E230; E240; E250) of the power supply to the electrical machine (10).

2. Method for controlling an electrical machine according to claim 1, characterized in that the reconfiguration step (E220) of the electrical machine (10) is triggered when:

> in a motor mode of the electric machine (10), the first calculator (15) determines that the torque gradient difference exceeds a first acceptability threshold for a duration greater than or equal to a first analysis duration; or, in a generator mode of the electric machine (10), the first calculator (15) determines that the torque gradient difference exceeds one second acceptability threshold for a duration greater than or equal to a second analysis duration; the first acceptability threshold and the second acceptability threshold preferably being different from each other.

3. Method for controlling an electrical machine according to claim 2, characterized in that the first acceptability threshold and the second acceptability threshold can be calibrated independently of each other.

4. Method for controlling an electrical machine according to any one of claims 2 to 3, characterized in that:

- the first acceptability threshold is between 5 and 50 Nm/s, preferably between 10 and 35 Nm/s, more preferably equal to 25 Nm/s; and or,

- the second acceptability threshold is between 3 and 30 Nm/s, preferably between 5 and 20 Nm/s, more preferably equal to 10 Nm/s.

5. Method for controlling an electrical machine according to any one of claims 2 to 4, characterized in that:

- said periodicity is chosen between 10 and 200 ms, preferably between 25 and 100 ms, more preferably between 40 and 75 ms; and or

- the first analysis duration and/or the second analysis duration is/are between 50 and 1000 milliseconds, preferably between 100 and 500 milliseconds, more preferably is/are equal to one and/or the other at 200 milliseconds.

6. Method for controlling an electric machine according to any one of claims 1 to 5, characterized in that the restoration step prohibits any restoration of power to the electric machine (10) by restarting the vehicle (5) and any restoration of power to the electrical machine (10) by the vehicle (5) itself (E230).

7. Method for controlling an electric machine according to any one of claims 1 to 5, characterized in that the restoration step (E240) authorizes restoration of power to the electric machine (10) by restarting the vehicle ( 5).

8. Method for controlling an electric machine according to any one of claims 1 to 5, characterized in that the restoration step prohibits any restoration of power to the electric machine (10) by restarting the vehicle (5) and by the vehicle (5) itself when the first calculator (15) has determined that the torque gradient difference has exceeded a first acceptability threshold for a duration greater than or equal to a first analysis duration in a motor mode of the electric machine (10), and, the restoration step (250) authorizes a restoration of power to the electrical machine (10) by restarting the vehicle (5) when the first computer (15) has determined that the difference in torque gradient has exceeded a second threshold of acceptability for a duration greater than or equal to a second analysis duration in a generating mode of the electric machine (10).

9. Computer program product capable of implementing the method of controlling an electric machine forming a drive motor towards a freewheel operating mode according to any one of claims 1 to 8.

10. Vehicle with an electric drive chain, characterized in that it is configured to be able to implement the control method according to any one of claims 1 to 8 and/or in which the computer program product of claim 9 is installed.