METHOD FOR CONTROLLING THE TORQUE OF AN ELECTRIC VEHICLE TRACTION MACHINE
By applying decrement and increment torque gradients within defined limits, the method addresses imprecise torque control in electric vehicles, ensuring smooth operation by eliminating drivetrain oscillations and respecting torque constraints.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Applications
- Current Assignee / Owner
- STELLANTIS AUTO SAS
- Filing Date
- 2024-12-06
- Publication Date
- 2026-06-12
AI Technical Summary
Existing methods for controlling electric traction machine torque in vehicles introduce imprecision and drag due to the use of preventive smoothness filters that prioritize maximum torque limitations over smoothness, leading to uncomfortable drivetrain oscillations.
A method that involves determining a filtered torque setpoint by applying decrement and increment torque gradients within minimum and maximum torque limits, ensuring precise control of the electric traction machine torque.
This approach eliminates the drag phenomenon and ensures precise torque control, maintaining smooth vehicle operation by adhering to both minimum and maximum torque constraints.
Smart Images
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Abstract
Description
Title of the invention: METHOD FOR CONTROLLING THE TORQUE OF AN ELECTRIC VEHICLE TRACTION MACHINE
[0001] The present invention relates to a method for controlling the torque of an electric traction machine in a vehicle. The invention thus concerns the technical field of controlling electric traction machines in electric or hybrid vehicles. This aspect of the invention has particularly interesting, but not exclusive, applications in the field of electric or hybrid vehicles with a power electrical network, for example, of the 48V or 400V type.
[0002] When the driver depresses the accelerator pedal, causing the vehicle to accelerate, or releases it, causing the vehicle to decelerate, the vehicle's passengers may feel jolts. These jolts are due to oscillations of the drivetrain as it passes through any mechanical play present in the drivetrain. This phenomenon is unpleasant for the vehicle's occupants. The driver generally experiences a feeling of discomfort, or even insecurity.
[0003] In order to reduce oscillations in the drivetrain when passing through mechanical clearances present in the drivetrain, as described in document FR-B1-3001685, it is known to implement a preventive smoothness filter function that filters the raw driver's torque setting. This function thus provides a preventive correction to the oscillations generated by this passage through mechanical clearances and significantly improves the longitudinal smoothness of the motor vehicle.
[0004] More specifically, it is known to determine a target torque setpoint for the electric traction machine, the target torque setpoint being equal to a driving torque setpoint limited by a minimum torque setpoint and a maximum torque setpoint. Then, via this preventive adjustment filter, it is known to determine a filtered torque setpoint. This filtered torque setpoint is then used to control the torque of the electric traction machine.
[0005] This type of preventive approval filter nevertheless presents some drawbacks. [Fig. 1] illustrates a real-life situation in which the target torque setpoint Cc is equal to the driver torque setpoint limited by the maximum torque setpoint Cmax and the minimum torque setpoint Cm in, for example to limit the discharge of the vehicle's battery.
[0006] More specifically, when the driver releases the accelerator pedal and the driver torque command is limited by the maximum torque command Cmax, the resulting target torque command Cc is filtered by means of a preventive smoothness filter. This filtering generates a filtered torque command Cf. As illustrated in [Fig. 1], while the priority is to respect the maximum torque limitation Cmax, which takes precedence over the vehicle's smoothness, this filtering adds drag T. The control of the electric traction machine using the filtered torque command is therefore imprecise.
[0007] The invention offers a solution to the problem mentioned above, by proposing a method for precisely controlling a torque of an electric traction machine of a vehicle.
[0008] In this context, the invention thus relates, in its broadest sense, to a method for controlling the torque of an electric traction machine of a vehicle, the method comprising the steps, executed by vehicle control means, of: • Detect a change in a driving torque setting; • Determine a target torque setpoint for the electric traction machine, said target torque setpoint being equal to the conductor torque setpoint limited by a minimum torque setpoint and a maximum torque setpoint; • Determine a filtered torque setpoint, said filtered torque setpoint being a function of said target torque setpoint, a decrement torque gradient and an increment torque gradient to be applied to the electric traction machine, said filtered torque setpoint being notable in that it is further limited by said minimum torque setpoint and said maximum torque setpoint.
[0009] The method according to this aspect of the invention further comprises a step, executed by the control means, of controlling, by means of the determined filtered torque setpoint, a torque applied by the electric traction machine.
[0010] Thanks to the method according to the invention, and more particularly to the limitation, via minimum and maximum torque setpoints, of the filtered torque setpoint used to control the electric traction machine, the filtered torque setpoint corresponds precisely to the target torque setpoint. More specifically, the drag phenomenon added by the filtering step of the prior art is eliminated by implementing the minimum and maximum torque setpoints to limit the filtered torque setpoint. The electric traction machine torque of the vehicle is thus precisely controlled.
[0011] In addition to the characteristics just mentioned in the preceding paragraph, the process according to this aspect of the invention may have one or more complementary characteristics from among the following, considered individually or according to all technically possible combinations.
[0012] According to a non-limiting aspect of the invention, the modification of a driving torque setpoint is formed by an acceleration or a deceleration.
[0013] According to a non-limiting aspect of the invention, the filtered torque setpoint Cf is determined by means of the following function: rfr JC 1 ï de, 1 1 cf = Cc+[ccx {[-^]^^]}] MI1\
[0014] With: • Cc = Target torque; • Cinc = Increment torque; • Cdec = Decrement pair; • Cmin = Minimum torque setpoint; • Cmax = Maximum torque setpoint.
[0015] According to a non-limiting aspect of the invention, the minimum torque setpoint and the maximum torque setpoint are determined according to the vehicle's energy criteria.
[0016] According to a non-limiting aspect of the invention, the minimum torque setpoint and the maximum torque setpoint are determined as a function of an operating state of a component of the vehicle.
[0017] According to a non-limiting aspect of the invention, the minimum torque setpoint and the maximum torque setpoint are determined according to a safe operating mode of the vehicle.
[0018] A different aspect of the invention relates to a computer program product downloadable from a communication network and / or recorded on a computer-readable medium and / or executable by a processor, the computer program product being notable in that it includes program code instructions for implementing the method according to any one of the aforementioned aspects of the invention, when the program is executed on a computer.
[0019] Another aspect of the invention relates to control means comprising a memory storing software instructions for the implementation of the method defined according to any one of the aforementioned aspects of the invention.
[0020] A different aspect of the invention relates to a motor vehicle powertrain comprising control means such as those mentioned above.
[0021] According to a non-limiting aspect of the invention, the powertrain is electric or hybrid.
[0022] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures.
[0023] [Fig-1] illustrates, schematically, a filtered driver torque setpoint according to the state of the art.
[0024] [Fig.2] illustrates, schematically, a powertrain according to a non-limiting example of the invention.
[0025] [Fig.3] illustrates, schematically, a method of controlling a torque of an electric vehicle traction machine according to a non-limiting embodiment of the invention.
[0026] [Fig.4] illustrates, schematically, a deceleration driving torque command controlled by means of the method of the invention described in support of [Fig.3].
[0027] [Fig.5] illustrates, schematically, a driving torque command for acceleration controlled by means of the method of the invention described in support of [Fig.3],
[0028] The figures are presented for illustrative purposes only and are in no way limiting of the invention.
[0029] Unless otherwise specified, the same element appearing on different figures has a unique reference.
[0030] The [Fig. 1] was described in the preamble to the description.
[0031] Figure 2 illustrates a powertrain 1 of an electric motor vehicle including: • A front wheel assembly 2 driven in rotation by an electric traction machine 3, and • Control means 4 arranged to execute the steps of the process of controlling a torque of the electric traction machine 3 of the vehicle according to the invention.
[0032] According to a non-limiting example of embodiment, the control means 4 are formed by a vehicle control unit, also called VCU (for Vehicle Control Unit in English).
[0033] The control means 4 comprise at least one processor and at least one memory storing software instructions for implementing the method according to the invention.
[0034] Figure 3 schematically illustrates the steps of an example of implementation of method 100 according to the invention. The steps are executed by the control means 4 of the powertrain 1.
[0035] The method 100 includes a step of determining 101 a modification of a driver torque setpoint. This driver torque setpoint is also referred to as the IVC instruction (for "Interpretation of Driver Will"). This modification of a driver's torque instruction corresponds to: • Releasing the accelerator pedal, reflecting a driver's desire to decelerate, results in a decrease in the driver's torque command, or • Pressing the accelerator pedal reflects a desire to accelerate by the driver, resulting in an increase in the driver's torque command.
[0036] This modification of a driver torque setpoint can be detected by a position sensor of the accelerator pedal of the powertrain 1, and then transmitted to the control means 4.
[0037] The method 100 then includes a step of determining 102 a target torque setpoint for the electric traction machine 3. The target torque setpoint is equal to the modified conductor torque setpoint, previously determined in step 101, limited by a minimum torque setpoint and a maximum torque setpoint.
[0038] According to a non-limiting example of embodiment, the minimum torque setpoint and the maximum torque setpoint can be determined, by the control means 4, according to energy criteria, such as a state of charge of the traction battery of the powertrain 1 and / or a consumption of electrical components of the vehicle.
[0039] According to another non-limiting embodiment, the minimum torque setpoint and the maximum torque setpoint can also be determined, by the control means 4, as a function of an operating state of a vehicle component, such as a high temperature of the electric traction machine limiting its performance or a state of brake wear.
[0040] According to a different, non-limiting embodiment, the minimum torque setpoint and the maximum torque setpoint can also be determined, by the control means 4, according to a safe operating mode of the vehicle imposing a torque limitation of the vehicle.
[0041] Depending on the target torque setpoint determined in the previous step 102, a predetermined decrement torque gradient and a predetermined increment torque gradient to be applied to said electric traction machine 3, the process 100 executes, via the control means 4, a step of determining 103 a filtered torque setpoint.
[0042] The decrement torque gradient can be determined in a map showing decrement torque gradients as a function of target torque instructions.
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[0051] Similarly, the increment torque gradient can be determined in a map showing increment torque gradients as a function of target torque setpoints. It should be noted that, advantageously, during this step 103, the filtered torque setpoint is further limited by the minimum torque setpoint and the maximum torque setpoint. In other words, the filtered torque setpoint is constrained between the minimum torque setpoint and the maximum torque setpoint. According to a non-limiting example implementation, the filtered torque setpoint Cf is defined by the following function: rf I dC 1 I dC, 1 ] ]MAX cf = Q + cc x t 7 - L l LJL dt • With : • Cc = Target torque; • Cinc = Increment torque; • Cdec = Decrement pair; • Cmin = Minimum torque setpoint; • Cmax = Maximum torque setpoint. The process 100 then includes a step of controlling 104 a torque applied by the electric traction machine 3 by means of the filtered torque setpoint determined during the previous step 103. To this end, the control means 4 can transmit the filtered torque setpoint to a controller of the electric traction machine 3. Figure 4 illustrates, following the detection of a decrease in the driver torque setpoint, the filtered torque setpoint determined during step 103. More specifically, • The Cc curve illustrates a decrease in the target torque setpoint reflecting a decrease in the driver's torque setpoint in Nm; • The Cmin curve illustrates the minimum torque setpoint in Nm; • The Cmax curve illustrates the maximum torque setpoint in Nm; • The Cf curve illustrates the filtered torque setpoint. More specifically, we can see that the filtered torque setpoint is as close as possible to the target torque setpoint corresponding to the driver's torque setpoint limited by the maximum torque setpoint. In other words, the drag present in the prior art has been eliminated due to the consideration of the maximum torque setpoint when determining the filtered torque setpoint.
[0052] Fig. 5 illustrates, following the detection of an increase in the driver torque setpoint, the filtered torque setpoint determined during step 103.
[0053] More specifically, • The Cc curve illustrates an increase in the target torque setpoint reflecting an increase in the driver's torque setpoint in Nm; • The Cmin curve illustrates the minimum torque setpoint in Nm; • The Cmax curve illustrates the maximum torque setpoint in Nm; • The Cf curve illustrates the filtered torque setpoint
[0054] It can be seen that the filtered torque setpoint is closest to the setpoint The target torque corresponds to the driver's torque setting, limited by the minimum torque setting. In other words, the drag present in the prior art has been eliminated due to the consideration of the minimum torque setting when determining the filtered torque setting.
[0055] The various aspects of the aforementioned invention offer numerous advantages. Among these, we can mention: • Respect the minimum and maximum driver torque limits in order to respect priority charging, vehicle torque limits, brake protection; etc... • Obtain the most accurate torque balance possible in the control to avoid torque control errors.
Claims
Demands
1. A method (100) for controlling the torque of an electric traction machine (3) of a vehicle, said method (100) comprising the steps, carried out by control means (4) of said vehicle, of: • Detecting (101) a change in a driving torque setpoint; • Determining (102) a target torque setpoint (Cc) of said electric traction machine (3), said target torque setpoint (Cc) being equal to said driving torque setpoint limited by a minimum torque setpoint (Cmin) and a maximum torque setpoint (Cmax); • Determining (103) a filtered torque setpoint (Cf), said filtered torque setpoint (Cf) being a function of said target torque setpoint (Cc), a decrement torque gradient and an increment torque gradient to be applied to said electric traction machine (3);• Said method (100) being characterized in that said filtered torque setpoint (Cf) is further limited by said minimum torque setpoint (Cmin) and said maximum torque setpoint (Cmax), and in that it comprises a step of controlling (104), by means of said filtered torque setpoint (Cf), a torque applied by said electric traction machine (3).
2. Method (100) according to the preceding claim, characterized in that the modification of a driving torque setpoint is formed by an acceleration or a deceleration.
3. Method (100) according to the preceding claim, characterized in that the filtered torque setpoint (Cf) is determined by means of the following function: c - c + [cx ! f^l 1 cf - cc+\cc* n M njjj - With: • Cc = Target torque; • Cinc = Increment torque; • Cdec = Decrement torque; • Cmin = Minimum torque setpoint; • Cmax = Maximum torque setpoint.
4. Method (100) according to any one of the preceding claims, characterized in that the minimum torque setpoint (Cm;„) and the maximum torque setpoint (Cmax) are determined according to energy criteria of the vehicle.
5. Method (100) according to any one of claims 1 to 3, characterized in that the minimum torque setpoint (Cm in) and the maximum torque setpoint (Cmax) are determined as a function of an operating state of a vehicle component.
6. Method (100) according to any one of claims 1 to 3, characterized in that the minimum torque setpoint (Cmin) and the maximum torque setpoint (Cmax) are determined according to a safe operating mode of the vehicle.
7. Product computer program downloadable from a communication network and / or recorded on a computer-readable medium and / or executable by a processor, characterized in that it includes program code instructions for implementing the method (100) according to any one of the preceding claims, when the program is executed on a computer.
8. Control means (4) comprising a memory storing software instructions for implementing the method (100) defined according to any one of the preceding claims 1 to 6.
9. Powertrain (1) of a motor vehicle comprising control means (4) according to the preceding claim.
10. Powertrain (1) according to the preceding claim, characterized in that it is electric or hybrid.