METHOD FOR CONTROLLING AN ELECTRIC TRACTION MACHINE OF A VEHICLE

Abstract

One aspect of the invention relates to a method (100) for controlling an electric traction machine of a vehicle, the method (100) comprising, when the vehicle is running, the steps of: - detecting (101) a failure of at least a first pressure sensor or a second pressure sensor of a brake booster of the vehicle, - determining (102) a speed value of the vehicle, - when a failure of at least one of the first pressure sensor or second pressure sensor is detected, determining (103) a torque value to be applied to drive wheels of the vehicle, depending on the determined speed value, to bring the vehicle to a predetermined safety speed value, - applying (104) the determined torque value to the drive wheels.

Description

DESCRIPTION TITLE OF THE INVENTION: METHOD FOR CONTROLLING AN ELECTRIC TRACTION MACHINE OF A VEHICLE

[0001] The present invention claims priority from French application No. 2207844 filed on 07 / 29 / 2022, the content of which (text, drawings and claims) is incorporated herein by reference.

[0002] One aspect of the invention relates to a method for controlling an electric traction machine of a vehicle, said controlling taking place successively upon detection of a failure of at least one pressure sensor of a braking amplifier included in the vehicle.

[0003] Another aspect of the invention relates to an electric or hybrid vehicle, in particular an automobile, constructed and arranged to implement a method for controlling an electric traction machine.

[0004] These aspects of the invention find particularly interesting applications in the field of safety of electric or hybrid motor vehicles.

[0005] A brake booster is usually implemented on a motor vehicle with the aim of amplifying the effort that a driver must exert on a brake pedal. To this end, a brake booster cooperates with an electric vacuum pump constructed and arranged to generate vacuum in the vehicle's brake booster. Each time the vehicle's brake pedal is pressed, vacuum is consumed to provide the braking assistance required by the vehicle's driver. As soon as the vacuum reserve falls below a predetermined threshold, the electric vacuum pump is activated to replenish the vacuum reserve contained in the brake booster.

[0006] The pressure generated by the vacuum pump in the brake booster is monitored by a pressure sensor. Specifically, this pressure sensor transmits pressure information to a vehicle computer, which checks that the detected pressure value is within an acceptable pressure range. If this value is outside this range, the pressure sensor is considered defective.

[0007] In order to detect false pressure measurements, it is also known from document US-A1-7467544 to redundant the pressure sensor of the brake amplifier. Below a threshold level of drift of the measurements made by the two sensors, a failure is signaled.

[0008] If such a process can detect a failure of one of the pressure sensors, the very existence of such a failure risks impacting the braking capacity of the vehicle.

[0009] The aim of the invention is to overcome the drawbacks of the prior art by proposing a method for securing the vehicle in the event of detection of a failure of a pressure sensor of a brake amplifier.

[0010] In this context, the invention thus relates, in its broadest sense, to a method for controlling an electric traction machine of an electric or hybrid vehicle, said method comprising, when the vehicle is moving, the steps, executed by vehicle control means, of: Detect a failure of at least one first pressure sensor or one second pressure sensor of a vehicle brake amplifier, Determine a vehicle speed value, The process being remarkable in that it further comprises the steps of: When a failure of at least one of the first pressure sensor or second pressure sensor is detected, determining a torque value to be applied to drive wheels of the vehicle, based on the determined speed value, to bring the vehicle to a predetermined safety speed value, Apply the determined torque value to the drive wheels using the electric traction machine.

[0011] By means of the method of the invention, when a failure of at least one pressure sensor of the brake amplifier is detected, the speed of the vehicle is brought to a predetermined safety speed, for example between 10 and 20 km / h so that the driver can stop the vehicle without braking assistance.

[0012] In addition to the characteristics which have just been mentioned in the preceding paragraph, the method according to the invention may have one or more additional characteristics among the following, considered individually or according to all technically possible combinations.

[0013] According to a non-limiting aspect of the invention, the method comprises a step, executed by the control means, of displaying, on a display console of the vehicle, a vehicle stop indicator light.

[0014] According to a non-limiting aspect of the invention, the method comprises a step, executed by the control means, of displaying, on a display console of the vehicle, a message reflecting that a failure of at least one of the first pressure sensor or second pressure sensor of the vehicle has been detected.

[0015] According to a non-limiting aspect of the invention, the step of detecting a failure of at least one of the first pressure sensor or second pressure sensor comprises the sub-steps of: Receive a first pressure measurement from the brake amplifier determined by means of the first pressure sensor, Receive a second pressure measurement from the brake booster determined by means of the second pressure sensor, Determine a pressure difference between the first and second pressure measurements, Repeat, periodically according to a first determined period, the sub-steps of receiving a first pressure measurement, receiving a second pressure measurement and determining a pressure difference, If the determined pressure deviation is greater than a pressure threshold for a second predetermined period, determining a failure of at least one of the first pressure sensor or second pressure sensor.

[0016] According to a non-limiting aspect of the invention, the method comprises a step, executed by the control means, of controlling a vacuum pump of the amplifier braking based on the lowest pressure measurement of the first and second pressure measurements.

[0017] According to a non-limiting aspect of the invention, when a failure of at least one of the first pressure sensor or second pressure sensor has been detected, it comprises the steps, executed via the control means, of: Periodically repeat according to the first determined period, the sub-steps of receiving a first pressure measurement, receiving a second pressure measurement and determining a pressure difference, If the determined pressure difference is below the pressure threshold for a third predetermined period, determining a restoration of operation of at least one of the first pressure sensor or second pressure sensor.

[0018] According to a non-limiting aspect of the invention, the method comprises a step, executed by the control means, of stopping applying the determined torque value to the drive wheels by means of the electric traction machine.

[0019] According to a non-limiting aspect of the invention, the method comprises a step, executed by the control means, of turning off the vehicle's stop light.

[0020] According to a non-limiting aspect of the invention, the method comprises a step, executed by the control means, of switching off the message reflecting that a failure of at least one of the first pressure sensor or second pressure sensor has been detected.

[0021] According to a non-limiting aspect of the invention, the method comprises a step, executed by the control means, of controlling a vacuum pump of the brake amplifier as a function of a pressure measurement carried out by the first pressure sensor or the second pressure sensor preselected as the reference sensor.

[0022] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures.

[0023] [Fig. 1] schematically illustrates an electric vehicle in accordance with a non-limiting aspect of the invention.

[0024] [Fig. 2] schematically represents an exemplary embodiment of a method for controlling an electric traction machine of an electric or hybrid vehicle according to a non-limiting aspect of the invention.

[0025] [Fig. 3] shows a reference curve that can be implemented in a method for controlling an electric traction machine of an electric or hybrid vehicle according to a non-limiting aspect of the invention.

[0026] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0027] Figure 1 schematically illustrates an electric vehicle 1 according to the invention.

[0028] The electric vehicle 1 includes: An electric traction machine 2, Two-wheel drive 3 rotated by the electric traction machine 2, A 4 brake amplifier, A vacuum pump 5, A first pressure sensor 6, A second pressure sensor 7, An 8 display console, and Control means 9 arranged to implement steps of a method for controlling an electric traction machine as illustrated in figure 2. The control means 9 can for example be formed by a vehicle control unit (better known by the acronym VCU for Vehicle Control Unit in English) and / or by an intelligent service box, better known by the acronym BSI.

[0029] Figure 2 illustrates an exemplary embodiment of a method 100 for controlling an electric traction machine 2 of an electric or hybrid vehicle 1 according to the invention.

[0030] It should be noted that the steps presented below of the method 100 are executed when the vehicle 1 is moving.

[0031] The method 100 comprises a step of detecting 101, via the control means 9 of the vehicle 1, a failure of at least one of the first pressure sensor 6 or second pressure sensor 7 of the braking amplifier 4 of the vehicle 1.

[0032] In a non-limiting implementation, the step of detecting 101 a failure of at least one of the first pressure sensor 6 and second pressure sensor 7 comprises the sub-steps of: Receive 101 a first pressure measurement of the brake amplifier 4 determined by means of the first pressure sensor 6, Receive 101 b a second pressure measurement from the brake amplifier 4 determined by means of the second pressure sensor 7, then Determine 101 c a pressure difference between the first and second pressure measurements.

[0033] To carry out the sub-step of determining 101 c a pressure difference, the control means 9 determine, for example, the pressure difference by taking the absolute value of the first pressure measurement from which the second pressure measurement is subtracted.

[0034] The detecting step 101 also comprises a step of repeating 101 d, periodically according to a first determined period, the sub-steps of receiving 101 a a first pressure measurement, receiving 101 b a second pressure measurement and determining 101 c a pressure difference.

[0035] In a non-limiting exemplary embodiment, the first determined period is between 100 and 300 milliseconds, typically 200 milliseconds.

[0036] The detecting step 101 also comprises, if the determined pressure difference is greater than a pressure threshold during a second predetermined period, a sub-step 101 of determining a failure of at least one of the first pressure sensor 6 or second pressure sensor 7.

[0037] In a non-limiting exemplary embodiment, the pressure threshold is between 0.1 bars and 0.3 bars, typically 0.2 bars.

[0038] In a non-limiting exemplary embodiment, the second determined period is between 1000 and 3200 milliseconds, typically 1600 milliseconds.

[0039] The method 100 also comprises a step of determining 102, via the control means 9, a speed value of the vehicle 1.

[0040] When a failure of at least one of the first pressure sensor 6 or second pressure sensor 7 is detected, the method 100 comprises a step of determining 103, via the control means 9, a torque value to be applied to the drive wheels 3 of the vehicle 1. The torque value to be applied is determined as a function of the speed value determined to bring the vehicle 1 to a predetermined safety speed value.

[0041] In a non-limiting exemplary embodiment, the predetermined safety speed value is between 10 and 30 km / h, for example 17 km / h.

[0042] The torque value to be applied is determined based on a mapping of torque values ​​as a function of speed values.

[0043] The torque value to be applied to the drive wheels 3 of the vehicle 1 can for example be determined by the control means 9 by means of a map similar to that illustrated in figure 3.

[0044] More specifically, Figure 3 illustrates a mapping of torque values ​​as a function of speed values ​​(this mapping depends on the vehicle characteristics).

[0045] It should be noted that when it comes to braking torque value, a - sign is written in front of the braking torque value. Such braking torque can be generated by the traction electric machine 2 when it operates in regenerative mode also known as regenerative.

[0046] When the torque value is an acceleration torque value, no sign is placed in front of the value.

[0047] For example, according to this mapping, if the determined vehicle speed value is 40km / h, the torque value to be applied to the vehicle's 3 drive wheels is -600Nm.

[0048] The method 100 further comprises a step 104 of applying the determined torque value to the drive wheels 3. To do this, the control means 9 control the electric traction machine 2 so as to apply an acceleration torque or a braking torque to the drive wheels 3 and bring the vehicle 1 to a predetermined safety speed value.

[0049] The method 100 comprises a step of displaying 105, on the display console 8 of the vehicle 1, a stop indicator light for the vehicle 1. This display can be controlled by the control means 9.

[0050] The stop light can be formed by the word STOP. As vehicle 1, and in particular the acceleration of vehicle 1, no longer responds to the driver's wishes, this light informs the driver of vehicle 1 that it is preferable to stop his vehicle.

[0051] The method 100 further comprises a step of displaying 106, on the display console 8, a message reflecting that a failure of at least one of the first pressure sensor 6 or second pressure sensor 7 of the brake amplifier 4 of the vehicle 1 has been detected. This message makes it possible to inform the driver that he must bring his vehicle to the after-sales service in order to repair the failure. This display can be controlled by the control means 9.

[0052] The method 100 comprises a step of controlling 107, via the control means 9, the vacuum pump 5 of the braking amplifier 4 as a function of the lowest pressure measurement among the first and second pressure measurements.

[0053] Thus, the vacuum pump 5 risks providing too much vacuum. This situation is preferable in order to secure braking.

[0054] The method 100 also comprises a step of recording 108 a fault code reflecting that a fault of at least one of the first pressure sensor 6 or second pressure sensor 7 of the brake amplifier 4 of the vehicle 1 has been detected. This recording step 108 can be executed by the control means 9.

[0055] When a failure of at least one of the first pressure sensor 6 or second pressure sensor 7 has been determined, the method 100 comprises the steps of: Repeat 109, periodically, via the control means 9, according to the first determined period, for example 200 milliseconds, the sub-steps of receiving 101 a a first pressure measurement, receiving 101 b a second pressure measurement and determining 101 c a pressure difference, then If the determined pressure difference is lower than the pressure threshold during a third predetermined period, determine 110, via the control means 9, a restoration of operation of at least one of the first pressure sensor 6 or second pressure sensor 7.

[0056] In a non-limiting exemplary embodiment, the third predetermined period is between 1000 and 3000 milliseconds, typically 2000 milliseconds.

[0057] In this exemplary embodiment, when a restoration of operation of at least one of the first pressure sensor 6 or second pressure sensor 7 is determined, the method 100 comprises the steps, executed via the control means 9, of: stopping 111 applying the determined torque value to the drive wheels 3 by means of the electric traction machine 2, Turn off 112 1st vehicle stop light 1 , Turn off 113 the message reflecting that a failure of at least one of the first pressure sensor 6 or second pressure sensor 7 has been detected, and Control 114 the vacuum pump 5 of the brake amplifier 4 according to the pressure measurement of the first sensor 6 or the second sensor 7 preselected as the reference sensor.

[0058] Thus, when the first sensor 6 is preselected as the reference sensor, when no failure of one of the first and second pressure sensors 6, 7 is detected, the vacuum generated in the brake amplifier 4 is a function of the pressure measurements made by the first sensor 6.

[0059] Conversely, when the second sensor 7 is preselected as the reference sensor, when no failure of one of the first and second pressure sensors 6, 7 is not detected, the vacuum generated in the brake amplifier 4 is a function of the pressure measurements made by the second sensor 7.

[0060] In this exemplary embodiment, when a restoration of operation of at least one of the first and second pressure sensors 6, 7 is determined, the method 100 comprises a step of recording 115 a restoration code reflecting that a restoration of operation of at least one of the first and second pressure sensors 6, 7 of the brake amplifier 4 of the vehicle 1 has been detected. This recording step 115 can be executed by the control means 9 of the vehicle.

[0061] It should be noted that a person skilled in the art is able to make different variations to the aforementioned aspects of the invention, for example by modifying the mapping or by modifying the values ​​of the first, second and / or third periods, or by modifying the value of the pressure threshold.

Claims

CLAIMS 1. Method (100) for controlling an electric traction machine (2) of an electric or hybrid vehicle (1), said method (100) comprising, when said vehicle (1) is moving, the steps, executed by control means (9), of said vehicle (1) of: - Detecting (101) a failure of at least a first pressure sensor (6) or a second pressure sensor (7) of a braking amplifier (4) of said vehicle (1), - Determine (102) a speed value of said vehicle (1), - Said method (100) being characterized in that it further comprises the steps of: o When a failure of at least one of the first pressure sensor (6) or second pressure sensor (7) is detected, determining (103) a torque value to be applied to drive wheels (3) of said vehicle (1), as a function of said determined speed value, to bring said vehicle (1) to a predetermined safety speed value, o Applying (104) said determined torque value to said drive wheels (3) by means of said electric traction machine (2).

2. Method (100) according to claim 1, characterized in that it comprises a step, executed by the control means (9), of displaying (105), on a display console (8) of said vehicle (1), a stop indicator light of said vehicle (1).

3. Method (100) according to any one of the preceding claims, characterized in that it comprises a step, executed by the control means (9), of displaying (106), on a display console (8) of said vehicle (1), a message reflecting that a failure of at least one of the first pressure sensor (6) or second pressure sensor (7) of the vehicle (1) has been detected.

4. Method (100) according to any one of the preceding claims, characterized in that the step of detecting (101) a failure of at least one of the first pressure sensor (6) or second pressure sensor (7) comprises the sub-steps of: - Receive (101 a) a first pressure measurement from the brake amplifier (4) determined by means of the first pressure sensor (6), - Receive (101 b) a second pressure measurement from the brake amplifier (4) determined by means of the second pressure sensor (7), - Determine (101c) a pressure difference between the first and second pressure measurements, - Repeat (101 d), periodically according to a first determined period, the sub-steps of receiving (101 a) a first pressure measurement, receiving (101 b) a second pressure measurement and determining (101 c) a pressure difference, - If said determined pressure difference is greater than a pressure threshold during a second predetermined period, determining (101 e) a failure of at least one of the first pressure sensor (6) or second pressure sensor (7).

5. Method (100) according to the preceding claim, characterized in that it comprises a step, executed by the control means (9), of controlling (107) a vacuum pump (5) of the braking amplifier (4) as a function of the lowest pressure measurement among the first and second pressure measurements.

6. Method (100) according to any one of claims 4 or 5, characterized in that when a failure of at least one of the first pressure sensor (6) or second pressure sensor (7) has been detected, it comprises the steps, executed via the control means (9), of: - Repeat (109) periodically according to the first determined period, the sub-steps of receiving (101 a) a first pressure measurement, receiving (101 b) a second pressure measurement and determining (101 c) a pressure difference, - If said determined pressure difference is lower than the pressure threshold during a third predetermined period, determining (110) a restoration of operation of at least one of the first pressure sensor (6) or second pressure sensor (7).

7. Method (100) according to the preceding claim, characterized in that it comprises a step, executed by the control means (9), of stopping (111) applying the determined torque value to the drive wheels (3) by means of the electric traction machine (2).

8. Method (100) according to any one of claims 6 or 7, characterized in that it comprises a step, executed by the control means (9), of turning off (112) the stop light of the vehicle (1).

9. Method (100) according to any one of claims 6 to 8, characterized in that it comprises a step, executed by the control means (9), of switching off (113) the message reflecting that a failure of at least one of the first pressure sensor (6) or second pressure sensor (7) has been detected.

10. Method (100) according to any one of claims 6 to 9, characterized in that it comprises a step, executed by the control means (9), of controlling (114) a vacuum pump (5) of the braking amplifier (4) as a function of a pressure measurement carried out by the first pressure sensor (6) or the second pressure sensor (7) preselected as a reference sensor.