Method for controlling a powertrain of an electrically powered vehicle

Abstract

Method for controlling a powertrain of an electric vehicle. The present invention relates to a method for controlling a powertrain of a vehicle comprising an electric traction or propulsion machine, the control method (1) comprising the steps of: - receiving a representative signal (SR) of a torque setpoint determined as a function of a position of an accelerator pedal of the vehicle, - acquiring a steering wheel angle (δ), - comparing the steering wheel angle (δ) with a threshold value, and the steering wheel angle (δ) is greater than the threshold value, a correction step of the received signal (SR), providing a modified signal (SM) representative of a corrected torque setpoint, the correction step comprising at least one clipping substep (146) during which the value of the modified signal (SM) is limited to a peak value,and - a step of sending a signal determined according to the modified signal (SM) to a powertrain control unit. (Figure 3),

Description

Title of the invention: Method for controlling a powertrain of an electrically powered vehicle

[0001] The present invention relates to the automotive field and more specifically concerns a method for controlling a powertrain comprising an electric traction or propulsion machine.

[0002] In a vehicle equipped with such a powertrain, the electric machine is capable of achieving very rapid torque variations. Indeed, when a driver of such a vehicle presses the vehicle's accelerator pedal, the new position of the accelerator pedal is sent to a computer in the vehicle, which translates it into a percentage setpoint for the maximum power achievable by the vehicle at the engine speed at which it is driven, then into a torque setpoint modifying the value of the control voltages of the electric machine, which almost instantly achieves the torque setpoint. The time taken between pressing the accelerator pedal and achieving the torque setpoint is therefore very short.

[0003] In a vehicle with a thermal engine, on the other hand, to achieve the torque setpoint provided by a vehicle computer, the thermal engine control system must adjust the air flow and the fuel flow arriving in the thermal engine.

[0004] With regard to the air flow, it is necessary to adjust certain actuators of the heat engine, in particular an air intake valve (or throttle body in the case of a spark-ignition engine) and possibly a boost pressure when the heat engine includes a turbocharger. As for the fuel flow, it is for example adjusted so as to adjust the richness of the air-fuel mixture in a closed loop to a set richness value (for example taken equal to 1 in the case of a spark-ignition engine).

[0005] The adjustment of the fuel flow rate can be considered almost instantaneous because it depends on the opening time of the fuel injectors, which is very short. On the other hand, concerning the air flow rate, a certain time elapses between the adjustment of the position of the actuators and the actual arrival of the air in the cylinders of the heat engine, due to the inertia of movement of the actuators and the distances to be covered by the air flow.

[0006] Consequently, obtaining the torque setpoint is not instantaneous with a thermal engine, but on the contrary goes through a more or less long transient phase.

[0007] On the contrary, in the case of an electric motor, the establishment of the setpoint of torque can be considered almost instantaneous, compared to that of a thermal engine, because in an electric motor the torque only depends on the application of a voltage and / or current value to the motor, which is very rapid.

[0008] However, the inventors have noted that a very rapid variation in torque can result, in certain cases, in an untimely disconnection of an intermediate transmission shaft of the vehicle, this intermediate transmission shaft being integral with a homokinetic transmission joint located on the side of a wheel of the vehicle.

[0009] It is recalled here that drive shafts and constant velocity joints are elements designed to transmit torque from a vehicle's gearbox to the vehicle's steered wheels. Drive shafts are metal rods equipped with constant velocity joints at each end. A constant velocity joint is connected to its drive shaft using splines, and locked onto the drive shaft using a split annular ring (also called a "circlip" in English), housed in a groove in the drive shaft.

[0010] [Fig. 1] shows a homokinetic joint 30 of the prior art, integral with an intermediate transmission shaft 50 of the transmission chain of a vehicle, and mounted movably in a wheel hub 40. This homokinetic joint 30 allows, whatever the angle of rotation of the steered wheels of the vehicle, an efficient transfer of torque between the torque at the output of the gearbox and the torque at the wheel to which the wheel hub 40 belongs. The homokinetic joint 30 comprises balls 34 held together in a ball cage. The ball cage is contained between on the one hand an internal housing 36 held fixed on the intermediate transmission shaft 30 by means of an annular ring or "circlip" 38, and on the other hand an external housing 32 of the homokinetic joint 30, this external housing comprising grooves allowing it to be held in the wheel hub 40.On the internal housing 36 and the external housing 32, there are arranged rolling tracks on which the balls 34 can move.

[0011] As shown [Fig. 1], the constant velocity joint 30 is subjected, when the vehicle to which it belongs is rolling, to an extraction force 60. This extraction force 60, directed towards the outside of the wheel, is likely to deform the annular ring 38 and to tear the intermediate transmission shaft 50 from the transmission joint 30, when the vehicle requires a high engine torque and when the steering angle of the wheels is too great.

[0012] As visible [Fig.2], the annular ring 38 is mounted in a groove 52 of the intermediate transmission shaft 50, and in a groove 362 of the internal housing 36 of the constant velocity joint 30. This latter groove 362 comprises a wall 364 inclined at an angle 0 relative to a direction orthogonal to the axis of the intermediate transmission shaft 50. This inclined wall 364 facilitates the assembly and disassembly of the internal housing 36 on the intermediate drive shaft 50, but may promote extraction of the intermediate drive shaft 50 at very high torque and wheel steering angle.

[0013] However, the dimensioning of the homokinetic joint 30, located on the side of a steered wheel, is generally defined based on several criteria, mainly its mechanical resistance, the wear of its materials and its endurance, but very little as a function of this extraction force 60.

[0014] Indeed, on a vehicle with a conventional internal combustion engine, the cases of use in which the torque required is very high while the steering angle of the wheels is very large, are rare and do not generally result in the extraction of the intermediate transmission shaft 50.

[0015] However, on an electric motor vehicle, since the electric torque gradients are achieved much more quickly, the extraction force 60 generates an untimely disconnection of the intermediate transmission shaft, in use cases such as a right-angle or hairpin turn, or maneuvers in a parking lot, which are carried out at high engine torque.

[0016] Therefore, in electric vehicles, it would be appropriate to take much greater account of the extraction force 60 in the dimensioning of the transmission joint 30, by making the inclined wall 364 with a smaller angle 0 than for a thermal vehicle. This solution would, however, generate difficulties for the assembly and maintenance of the transmission joint 30.

[0017] The present invention remedies at least in part the drawbacks of the state of the art set out above, by proposing a method for controlling a vehicle powertrain with at least partially electric motorization, an associated computer program and calculator, which make it possible to avoid the extraction of an intermediate transmission shaft from its constant velocity transmission joint, while not resorting to restrictive oversizing measures.

[0018] To this end, the present invention proposes a method for controlling a powertrain of a vehicle, the powertrain comprising at least one electric traction or propulsion machine, the control method comprising the steps of: - reception of a signal representative of a torque setpoint evolving as a function of time, the torque setpoint being determined as a function of a position of an accelerator pedal of the vehicle, - acquisition of a representative value of a steering wheel angle evolving over time, the control method being characterized in that it further comprises a step of comparing the value representative of the steering wheel angle with a threshold value, the comparison step being followed, when the representative value of the steering wheel angle is greater than the threshold value: - a step of correcting the received signal, providing a modified signal representative of a corrected torque setpoint, the correction step comprising at least one clipping sub-step during which the value of the modified signal is limited to a peak value, and - a step of sending to a control unit of the powertrain a signal determined as a function of the modified signal.

[0019] Thanks to the invention, the torque supplied by the powertrain is restricted to a peak torque value, which does not allow, in the moving vehicle, the extraction of an intermediate transmission shaft from its constant velocity joint. In addition, this solution makes it possible to keep, in the vehicle, constant velocity joints sized in such a way that their disassembly remains possible, thus limiting the cost of after-sales repairs. The invention makes it possible to improve the durability and reliability of electric vehicle transmissions, without additional costs linked to oversizing the constant velocity joints.

[0020] In the control method according to the invention, the signal representative of a torque setpoint is for example a signal established by a computer of the vehicle as a function of the available engine and battery power, or a “raw” torque signal requested by the driver, translating the depression of the accelerator pedal between a maximum depression value and a minimum depression value, and interpreting a desire of the driver to obtain a certain acceleration. The value representative of an angle at the steering wheel is for example a steering angle of the steering wheel relative to a reference position of the steering wheel, or an angle of rotation of a steering column, such a value always being counted positively, both in the clockwise and counterclockwise direction of the steering wheel.Finally, the torque setpoint is a torque setpoint for the vehicle's electrical machine, or a torque setpoint combining a torque setpoint for a vehicle's thermal engine and for the vehicle's electrical machine.

[0021] It should also be noted that the signal representing a torque setpoint is always positive, including if the vehicle is in reverse, or if the vehicle's brake pedal is actuated (in which case a negative or resistive torque is applied to the vehicle's wheels but without reducing the value of the torque setpoint).

[0022] According to an advantageous characteristic of the control method according to the invention, the correction step also comprises a sub-step of limiting the slope to a maximum slope value, which is implemented when the slope of the received signal is su higher than the maximum slope value. This feature limits the slope of the torque setpoint that will be supplied to the powertrain, and further reduces the risk of extraction of the intermediate drive shaft.

[0023] Advantageously in the control method according to the invention, when the value representative of the steering wheel angle is lower than the threshold value, the comparison step is followed by a step of saturating a slope of the received signal, providing a corrected signal whose slope is limited to a slope limit value, and a step of sending to the control member of the powertrain a signal determined as a function of the corrected signal. This makes it possible to smooth the behavior of the powertrain between the driving phases where the value representative of the steering wheel angle is higher than the threshold value and the driving phases where the value representative of the steering wheel angle is lower than the threshold value. Thus the vehicle is more easily maneuverable for its driver.The slope limit value is for example equal to the maximum slope value when the received signal is of a value lower than the peak value, and lower than this maximum slope value when the received signal is of a value higher than the peak value. In this control method according to the invention, the limitation of the slope is done in absolute value of the value of this slope, the limit and maximum slope values ​​being positive.

[0024] Advantageously again, when the correction step is activated while the value of the received signal is greater than the peak value, the value representative of the steering wheel angle passing from a value lower than the threshold value to a value higher than the threshold value, then the clipping sub-step is preceded by a sub-step of progressive reduction to the peak value, the modified signal provided by the correction step having a value progressively passing from the value of the received signal to the peak value. This characteristic of the invention also makes it possible to smooth the behavior of the powertrain between its different driving phases. In particular, this characteristic avoids the occurrence of shocks due to unlimited variations in torque, which would very significantly degrade driving pleasure, for example during maneuvers.

[0025] Preferably, the progressive reduction sub-step is carried out according to a slope of absolute value lower than the maximum slope value. This improves the handling of the vehicle, at high torque.

[0026] Similarly, in the control method according to the invention, when the value representative of the steering wheel angle changes from a value greater than the threshold value to a value less than the threshold value while the value of the received signal is greater than the peak value, then the corrected signal is a signal gradually changing from the peak value to the value of the received signal.

[0027] Preferably, the corrected signal gradually passes from the peak value to the value of the received signal according to a slope of absolute value lower than the maximum value. slope. The vehicle's maneuverability is preserved at high torque.

[0028] It should be noted that the control method according to the invention is carried out continuously while the vehicle is running, the steps of the invention being iterated. The modified signal and the corrected signal together form a signal representative of a corrected torque setpoint for all steering wheel angle values. This signal is then sent as is to the powertrain control member in the sending steps of the control method according to the invention, or, in particular when the received signal is a “raw” requested torque signal, to the vehicle computer which then determines, as a function of additional constraints, a signal to be sent to the powertrain control member during the sending steps. These constraints concern, for example, the powers available in the traction or propulsion battery, the powers achievable by the vehicle’s engine(s), or constraints linked to a specific context such as a gear change.These additional constraints can lead to a further reduction in the torque setpoint sent to the powertrain. However, it should be noted that the correction step of the control method according to the invention does not take these constraints into account, and therefore only uses the value representative of the steering wheel angle and the received signal as dynamic input data.

[0029] In one embodiment of the invention, the threshold value is taken equal to a maximum steering wheel angle value subtracted by a value between four and six degrees. Preferably, this threshold value is taken equal to the maximum steering wheel angle value subtracted by five degrees. The maximum steering wheel angle value is that available at a relatively low speed of the vehicle, the amplitude of the steering wheel available to the driver generally being restricted at high speed.

[0030] The threshold value is for example derived from a map giving the threshold value or said value to be subtracted from the maximum steering angle value, as a function of a critical wheel steering angle. This critical wheel steering angle is itself a function of the type of vehicle. The map is for example on a remote server, queried by the vehicle after each vehicle maintenance step.

[0031] The invention also relates to a computer program comprising program code instructions for executing the steps of the control method according to the invention, when said instructions are executed on a computer of the vehicle.

[0032] The invention also relates to a vehicle computer configured to execute the computer program according to the invention. The software implementation of the invention in the computer makes the invention very simple to implement, since it reuses existing resources in the vehicle such as the computer, sensors and communication paths between these sensors and the computer.

[0033] The computer program and the calculator have advantages similar to those of the control method according to the invention.

[0034] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several exemplary embodiments given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which:

[0035] [Fig-1] already described in relation to the prior art, illustrates in section a homokinetic transmission joint in a wheel hub, mounted on an intermediate transmission shaft,

[0036] [Fig.2] also already described in relation to the prior art, represents an agrand [Fig.l] at the level of an annular ring making it possible to block an internal housing of the constant velocity transmission joint on the intermediate transmission shaft,

[0037] [Fig.3] represents steps of a control method according to the invention, of a powertrain of a vehicle,

[0038] [Fig.4] illustrates the vehicle in which the control method is implemented according to the invention of [Fig.3],

[0039] [Fig.5] represents more completely the steps of the control method according to the invention represented [Fig.3],

[0040] [Fig.6] represents the evolution of the speed and the angle at the wheel of the vehicle of the [Fig.4], during rolling phases in which the invention is implemented, and

[0041] [Fig.7] represents the evolution of a torque instruction requested by the driver of the vehicle during the driving phases of [Fig.6], and the evolution of this torque setpoint modified or corrected by the control method according to the invention illustrated in figures 3 and 5.

[0042] According to one embodiment of the invention, a control method 1 according to the invention shown [Fig. 3] is implemented in hardware and / or software in a vehicle 2 illustrated [Fig. 4], equipped with an electric or hybrid electric powertrain 26. The powertrain 26 comprises in particular an electric traction or propulsion machine.

[0043] When a driver of the vehicle 2 actuates the accelerator pedal, the position of this accelerator pedal is fed back to a computer 24 of the vehicle 2 via an analog circuit, and converted into a digital signal. In this embodiment of the invention, this digital signal corresponds to a “raw” torque setpoint, i.e. derived directly from the position of the accelerator pedal, and is received in a first reception step 11 of the control method according to the invention, by the computer 24 of the vehicle 2, thanks to a central computer bus to which it is connected, this bus also being called CAN network (from the English “Controller Area Network”). The signal received SR in this reception step 11 is therefore a signal re representative of a torque setpoint evolving as a function of time t, which is the image of the “will of a driver” of the vehicle 2, more precisely of his will to obtain a certain acceleration, in accordance with the fundamental principle of dynamics which links the acceleration of the vehicle to the applied torque, without intermediate processing of this torque setpoint by the computer 24 of the vehicle 2. This representative signal is a signal with positive values ​​between a minimum value CO of zero and a maximum value Cl which is strictly positive.

[0044] A second step 12 of the control method according to the invention, illustrated [Fig. 4], is the acquisition by the computer 24 of a value representative of a steering wheel angle evolving as a function of time t. In this embodiment of the invention, this representative value is a steering wheel angle value δ, that is to say a steering angle of the steering wheel 22 of the vehicle 2 by the driver, relative to a reference position. This angle is counted positively regardless of whether the steering wheel is turned to the right in a clockwise direction or to the left in an anti-clockwise direction. The vehicle 2 more precisely comprises a steering wheel steering angle sensor, the measurements of which are sent to the computer 24 by the central computer bus. The reception steps 12 and 11 of acquisition are carried out in parallel and continuously by the computer 24.

[0045] As shown [Fig.5], the reception steps 12 and 11 of acquisition are followed by a step 13 of comparing the steering wheel angle value ô with a threshold value ôs, which is a strictly positive value, taken here equal to a maximum steering wheel angle value that the driver can achieve, minus five degrees. The comparison step 13 is implemented by the computer 24 of the vehicle 2. When the computer 24 determines in this step that the steering wheel angle value ô is strictly greater than the threshold value ôs, then it implements (branch N) a step 14 of correcting the previously received signal SR, resulting in a modified signal SM.

[0046] The correction step 14 modifies the received signal SR during a transient period of passage of the steering wheel angle value ô above the threshold value ôs. In the prolonged periods where the received signal SR has a low slope, a low value, and where the steering wheel angle value ô remains below the threshold value ôs, the values ​​of the modified signal SM are equal to the values ​​of the received signal SR.

[0047] When the received signal SR is above a peak value Cs equal to 270 Nm (Newton per meter) in this embodiment of the invention, the correction step 14 therefore comprises a clipping sub-step 146, implemented by clipping means 244 (referenced [Fig.3]) of the computer 24, during which the value of the modified signal SM is limited to this peak value Cs.

[0048] Similarly, when the slope in absolute value of the received signal SR is strictly greater than a maximum slope value am, the correction step 14 comprises a slope limitation sub-step 142 to the maximum slope value am, implemented by ramp limitation means 242 of the computer 24. These means 244 and 242 of the computer 24 are, for example, digital filters. For example, after a period of time where the received signal SR has remained below the peak value Cs with a slope less than or equal to the maximum slope value am, if the received signal SR starts from an instant t0 to increment by a gradient strictly greater than this maximum slope value am, we have:

[0049] SM(t) = Min (SRO + am*t, Cs) over this period of increase of the SR signal with high gradient,

[0050] Where SM(t) is the value of the modified signal SM at time t, SRO the value of the received signal SR at time t0, and Min (x,y) the minimum operator of the variables x and y.

[0051] Finally, when the correction step 14 is activated while the value of the received signal SR is greater than the peak value Cs, the steering wheel angle value ô having just passed from a value less than or equal to the threshold value ôs to a value strictly greater than the threshold value ôs, then the clipping sub-step 146 is preceded by a sub-step 144 of progressive reduction of the value of the received signal SR down to the peak value Cs. In other words, the modified signal SM is such that:

[0052] SM(t) = Max (SRI - a*t, Cs) as long as SR(t) > Cs,

[0053] Where SR(t) is the value of the received signal SR at time t, SRI the value of the received signal SR at the time when the steering wheel angle value ô has just passed to a value strictly greater than the threshold value ôs, has a predefined transient slope, and Max (x,y) the maximum operator of the variables x and y.

[0054] The transient slope a is here a positive value less than or equal to the maximum slope value am.

[0055] The modified signal SM from the correction step 14 is then consolidated by the computer 24 as a function of data linked in particular to the power available in a traction battery of the vehicle 2, to the power that can be supplied by the electric machine of the powertrain 26 and possibly to contextual data such as a gear change. The determined signal Tfl following this consolidation is for example a torque setpoint, sent by the computer 24, in a sending step 15, via the central computer bus, to a control member of the powertrain, which will translate this torque setpoint into control voltages of the electric machine.

[0056] When, following the comparison step 13, the computer 24 determines that the steering wheel angle value ô is less than or equal to the threshold value ôs, then it implements (branch O) a saturation step 16 of a slope of the received signal SR, providing a corrected signal SC whose slope is limited to a limit slope value al. The limit slope value al can be taken equal to the maximum slope value am or to a lower value. Thus, after a period of time where the received signal SR remained with a slope lower than the limit value of slope al, if the received signal SR begins from an instant t2 to increment by a gradient strictly greater than this limit value of slope al, we have:

[0057] SC(t) = SR2 + al*t over this period of increase of the SR signal with high gradient,

[0058] Where SC(t) is the value of the corrected signal SC at time t and SR2 the value of the signal SR at time t2.

[0059] Similarly to step 15, the corrected signal SC from the saturation step 16 is then consolidated by the computer 24 as a function of data linked in particular to the power available in a traction battery of the vehicle 2, to the power that can be supplied by the electric machine of the powertrain 26 and possibly to contextual data such as a gear change. The determined signal Tf2 following this consolidation is then sent by the computer 24, in a sending step 17, via the central computer bus, to the control unit of the powertrain, which will translate this torque setpoint into control voltages of the electric machine. Returning to [Fig.3], the comparison step 13 is implemented by a logic flip-flop 246. When the steering wheel angle value ô is strictly greater than the threshold value ôs, then the received signal SR is transmitted to an input 0 of the flip-flop 246, which also integrates a digital filter 248 operating the slope saturation step 16. When, on the contrary, the steering wheel angle value ô is less than or equal to the threshold value ôs, then the modified signal SM is transmitted to an input 1 of the flip-flop 246, which also operates the progressive decrease sub-step 144 using the differently configured digital filter 248.

[0060] The digital filter 248 in fact makes it possible to smooth the transitions between the modified signal SM and the corrected signal SC when the steering wheel angle value ô passes above or below the threshold value ôs, by limiting these transitions to a slope always less than or equal to the maximum slope value am.

[0061] Thus, when the steering wheel angle value ô changes from a value strictly greater than the threshold value ôs to a value less than or equal to the threshold value ôs while the value of the received signal SR is greater than the peak value Cs, then the corrected signal SC at the output of flip-flop 246 is a signal gradually changing from the peak value Cs to the value of the received signal SR, with a slope of value less than or equal to the maximum slope value am. For example, during this transition period:

[0062] SC(t) = Cs + 0.5am*t

[0063] The sequences of steps 13, 14, 15 or 13, 16, 17 are of course repeated depending on the current steering wheel angle value δ.

[0064] In this embodiment of the invention, the steps of the method are implemented implemented in software by the computer 24. However, the slope limiting means 242, clipping means 244 and the digital filter 248 can also perform their functions in analog form. Thus, as a variant, if the received signal SR is a raw analog signal of the accelerator pedal position, steps 11 to 14 and 16 of the method are carried out by an analog circuit, the output of which is then digitized to be sent to the computer 24.

[0065] It should also be noted that in this embodiment of the invention, the correction step 14 is implemented when the steering wheel angle value ô is strictly greater than the threshold value ôs, however, as a variant, the correction step 14 is implemented when the steering wheel angle value ô is greater than or equal to the threshold value ôs, the slope saturation step 16 then being implemented when the steering wheel angle value ô is strictly less than the threshold value ôs, and when the received signal SR has too high a slope. Similarly, the strict inequality conditions on the peak, maximum slope or slope limit values ​​are, as a variant, replaced by non-strict inequality conditions without changing the nature of the invention.

[0066] Figures 6 and 7 illustrate an example of use of the invention on the vehicle 2, moving at a speed V, in revolutions per minute, not exceeding 2000 revolutions per minute. The abscissas in these figures correspond to the time elapsed in seconds from an initial instant. In [Fig.6] the ordinate of the speed V versus time diagram is in revolutions per minute and the ordinate of the steering wheel angle diagram ô versus time is in percentage of the steering wheel angle threshold value ôs. The ordinate in [Fig.7] is in Newton per meter.

[0067] During a first phase <pl de roulage, l’angle au volant ô est au-dessus de la valeur seuil ôs, puis lors d’une deuxième phase q> 2 consecutive rolling phases in the first phase <pl de roulage, l’angle au volant ô est en dessous de la valeur seuil ôs, et enfin lors d’une troisième phase q> 3 of rolling following the second rolling phase q>2, the steering wheel angle ô is again above the threshold value ôs.

[0068] During the first phase <pl de roulage, le signal reçu SR à l’étape 11 passe très rapidement d’une valeur quasi nulle à une valeur supérieure à la valeur crête Cs et reste ensuite à cette valeur supérieure pendant cette première phase q> 1. This higher value corresponds here to a maximum torque value of 300Nm. The modified signal SM generated by the invention is therefore a signal which passes a little less quickly from the almost zero value to the peak value Cs, here 270Nm, with the maximum slope value am, taken here equal to 500Nm / s (Newton per meter per second). The modified signal SM then remains at this peak value Cs until the second rolling phase q>2.

[0069] During the second rolling phase q>2, the signal received SR in step 11 remaining at the maximum torque value of 300Nm, the corrected signal SC generated by the invention goes from the peak value Cs of 270Nm to this maximum torque value of 300Nm with a gentler slope, taken here equal to 100Nm / s, then remains at this maximum torque value until the third rolling phase q>3.

[0070] During the third rolling phase q>3, the signal received SR in step 11 remaining at the maximum torque value of 300Nm, the modified signal SM generated by the invention goes from the maximum torque value of 300Nm to the peak value Cs of 270Nm with a negative slope of absolute value taken equal to a slope limit value of 100Nm / s, and then remains at this peak value Cs during the third rolling phase q>3.

[0071] The steering wheel angle threshold value ôs is, in this embodiment of the invention, taken equal to the maximum steering wheel angle value available to the driver at speed V, subtracted by five degrees. This steering wheel angle threshold value ôs itself depends on the type of constant velocity joint used. Indeed, if the vehicle has high-quality constant velocity joints, the phenomenon of extraction of the intermediate transmission shaft occurs as soon as the wheels are turned by an angle greater than a critical angle of between 47° and 50°, whereas if the vehicle has more basic constant velocity joints, this critical angle is lower, between 43° and 46°.

[0072] The query of a remote server containing up-to-date data on the vehicle 2 is therefore, for example, used by the computer 24 to retrieve the threshold value ôs. A map is possibly used, taking as input this critical steering angle of the wheels, itself a function of a type of constant velocity joint, and providing as output a threshold value ôs of steering angle.

[0073] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention. In particular, the characteristics of the different variant embodiments can be combined to achieve the invention, insofar as these variants are not incompatible with each other.

Claims

Claims

1. Method for controlling (1) a powertrain (26) of a vehicle (2), the powertrain (26) comprising at least one electric traction or propulsion machine, the control method (1) comprising the steps of: - receiving (11) a signal (SR) representative of a torque setpoint evolving as a function of time (t), the torque setpoint being determined as a function of a position of an accelerator pedal of the vehicle (2), - acquiring (12) a value representative of a steering wheel angle (ô) evolving as a function of time (t), the control method (1) being characterized in that it further comprises a step of comparing (13) the value representative of the steering wheel angle (ô) with a threshold value (ôs), the comparison step (13) being followed, when the value representative of the steering wheel angle (ô) is greater than the threshold value (ôs): - a step of correcting (14) the received signal (SR),providing a modified signal (SM) representative of a corrected torque setpoint, the correction step (14) comprising at least one clipping sub-step (146) during which the value of the modified signal (SM) is limited to a peak value (Cs), and - a sending step (15) to a control member of the powertrain (26) of a signal (Ffl) determined as a function of the modified signal (SM), the correction step (14) also comprising a slope limitation sub-step (142) to a maximum slope value (am), which is implemented when the slope of the received signal (SR) is greater than the maximum slope value (am).,

2. Control method (1) of a powertrain (26) of a vehicle (2) according to claim 1, in which when the value representative of the steering wheel angle (ô) is less than the threshold value (ôs), the comparison step (13) is followed by a step of saturating (16) a slope of the received signal (SR), providing a corrected signal (SC) whose slope is limited to a slope limit value (al), and a step of sending (17) to the control member of the powertrain (26) a determined signal (Ff2) as a function of the corrected signal (SC).

3. Method for controlling (1) a powertrain (26) of a vehicle (2) according to claim 1 or 2, wherein when the correction step (14) is activated while the value of the received signal (SR) is greater than the peak value (Cs), the value representative of the steering wheel angle (ô) passing from a value lower than the threshold value (ôs) to a value higher than the threshold value (ôs), then the clipping sub-step (146) is preceded by a sub-step of progressive reduction (144) down to the peak value (Cs), the modified signal (SM) provided by the correction step (14) having a value progressively passing from the value of the received signal (SR) to the peak value (Cs).

4. Method for controlling (1) a powertrain (26) of a vehicle (2) according to claim 3, in which the progressive reduction sub-step (144) is carried out according to a slope of absolute value less than the maximum slope value (am).

5. Control method (1) of a powertrain (26) of a vehicle (2) according to any one of claims 1 to 4, wherein when the value representative of the steering wheel angle (ô) changes from a value greater than the threshold value (ôs) to a value less than the threshold value (ôs) while the value of the received signal (SR) is greater than the peak value (Cs), then the corrected signal (SC) is a signal gradually changing from the peak value (Cs) to the value of the received signal (SR).

6. Control method (1) of a powertrain (26) of a vehicle (2) according to claim 5, in which the corrected signal (SC) gradually changes from the peak value (Cs) to the value of the received signal (SR) according to a slope of absolute value less than the maximum slope value (am).

7. Control method (1) of a powertrain (26) of a vehicle (2) according to any one of claims 1 to 6, in which the threshold value (ôs) is taken equal to a maximum steering wheel angle value subtracted by a value between four and six degrees.

8. Control method (1) of a powertrain (26) of a vehicle (2) according to claim 7, in which the threshold value (ôs) comes from a map giving the threshold value (ôs) or said value to be subtracted from the maximum steering wheel angle value, as a function of a critical steering angle of the wheels.

9. Computer program comprising program code instructions for executing the steps of the control method (1) according to any one of claims 1 to 8, when said instructions are executed on a computer (24) of the vehicle (2).

10. Vehicle (2) computer (24) configured to execute the computer program according to claim 9.

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