US-12617292-B2 - Method of controlling drive system torque of electric vehicle

US12617292B2US 12617292 B2US12617292 B2US 12617292B2US-12617292-B2

Abstract

A method of controlling a drive system torque of an electric vehicle for generating a torque by evading a backlash band to prevent the occurrence of backlash in the drive system includes determining, by a controller, whether a plurality of predetermined entry conditions for entering a responsiveness priority mode of the vehicle are satisfied in a predetermined order based on vehicle driving information in a state in which control of a power priority mode is performed, and transitioning, by the controller, a mode to the responsiveness priority mode when it is determined that the plurality of entry conditions are sequentially satisfied and performing control of the responsiveness priority mode.

Inventors

Ji Won Oh
Ho Wook Lee
Jeong Soo Eo

Assignees

HYUNDAI MOTOR COMPANY
KIA CORPORATION

Dates

Publication Date: 20260505
Application Date: 20231024
Priority Date: 20230523

Claims (18)

1 . A method of controlling a drive system torque of an electric vehicle, the method comprising: determining, by a controller, an entire torque command required for travel of the vehicle; determining, by the controller, whether a plurality of predetermined entry conditions for entering a responsiveness priority mode of the vehicle are satisfied in a predetermined order based on vehicle driving information in a state in which control of a power priority mode in which front wheel torque control and rear wheel torque control are performed using a front wheel torque command and a rear wheel torque command respectively is performed; and transitioning, by the controller, a mode to the responsiveness priority mode in which the front wheel torque control and the rear wheel torque control are performed using the front wheel torque command and the rear wheel torque command for evading a backlash band, which is a torque region in which backlash of a drive system occurs, in response that the plurality of entry conditions are sequentially satisfied and performing control of the responsiveness priority mode, wherein the vehicle driving information for determining whether the plurality of entry conditions are satisfied includes a brake pedal position input value, a vehicle longitudinal acceleration, a steering wheel angle which is a steering input value, a vehicle transverse acceleration, the entire torque command, and an accelerator position input value, wherein the controller determines whether each of the plurality of entry conditions is satisfied based on a result of comparing each of the vehicle driving information with a respective preset threshold stored in a memory, and sequentially determines whether the entry conditions are satisfied in an order of a first entry condition, a second entry condition, and a third entry condition, wherein the plurality of entry conditions include: the first entry condition in which the brake pedal position input value is greater than a preset brake input threshold and an absolute value of the vehicle longitudinal acceleration is greater than a preset longitudinal acceleration threshold; the second entry condition in which the steering wheel angle is greater than a preset steering threshold and an absolute value of the vehicle transverse acceleration is greater than a preset transverse acceleration threshold; and the third entry condition in which there is no brake pedal position input or an absolute value of the entire torque command is smaller than a preset entry determination torque threshold.
2 . The method of claim 1 , wherein in the performing of the control of the responsiveness priority mode, the front wheel torque command is determined to be a value which is smaller than or equal to a front wheel maximum torque threshold set to a negative (−) torque value, and the rear wheel torque command is determined to be a value which is greater than or equal to a rear wheel minimum torque threshold set to a positive (+) torque value.
3 . The method of claim 2 , wherein the front wheel maximum torque threshold is set to a value which is smaller than a lower limit threshold in the backlash band, which is the torque region in which the backlash occurs in a front wheel side drive system, and wherein the rear wheel minimum torque threshold is set to a value which is greater than an upper limit threshold in the backlash band, which is the torque region in which the backlash occurs in a rear wheel side drive system.
4 . The method of claim 3 , wherein each of the backlash band of the front wheel side drive system and the backlash band of the rear wheel side drive system is set to a torque range including a zero torque in a range of the lower limit threshold, which is the negative (−) value, and the upper limit threshold, which is the positive (+) value.
5 . The method of claim 2 , wherein in the responsiveness priority mode, the controller is configured to: determine the rear wheel torque command to be the rear wheel minimum torque threshold in response that the entire torque command is smaller than or equal to the rear wheel minimum torque threshold after comparing the entire torque command with the rear wheel minimum torque threshold; and determine the front wheel torque command to be a value obtained by subtracting the determined rear wheel torque command from the entire torque command.
6 . The method of claim 2 , wherein in the responsiveness priority mode, the controller is configured to: determine the front wheel torque command to be the front wheel maximum torque threshold in response that the entire torque command is greater than or equal to the front wheel maximum torque threshold after comparing the entire torque command with the front wheel maximum torque threshold; and determine the rear wheel torque command to be a value obtained by subtracting the determined front wheel torque command from the entire torque command.
7 . The method of claim 2 , wherein in the responsiveness priority mode, the front wheel torque command and the rear wheel torque command are determined so that a value obtained by summing the front wheel torque command and the rear wheel torque command follows the entire torque command.
8 . The method of claim 1 , wherein the controller is configured to transition the mode to the responsiveness priority mode in response that all of the plurality of entry conditions are satisfied in an order of the first entry condition, the second entry condition, and the third entry condition.
9 . The method of claim 1 , wherein the controller is configured to: store a satisfaction history indicating that a corresponding entry condition has been satisfied whenever the first entry condition, the second entry condition, and the third entry condition are satisfied; and determine that the entry conditions of the responsiveness priority mode are satisfied so that the mode is transitioned to the responsiveness priority mode in response that the second entry condition is satisfied in a state in which a satisfaction history of the first entry condition is stored and present and the third entry condition is satisfied in a state in which a satisfaction history of the second entry condition is stored and present.
10 . The method of claim 9 , wherein the controller is configured to: among the first entry condition and the second entry condition and among the second entry condition and the third entry condition, determine that the entry conditions of the responsiveness priority mode are not satisfied in response that there is no satisfaction history of a preceding condition, which is an entry condition of a preceding order even when a following condition, which is an entry condition of a following order, is satisfied; and delete and initialize the satisfaction history of the preceding condition in response that the following condition is satisfied in a state in which the satisfaction history of the preceding condition is present.
11 . The method of claim 10 , wherein the controller is configured to: among the first entry condition and the second entry condition and among the second entry condition and the third entry condition, determine that the entry conditions of the responsiveness priority mode are not satisfied in response that there is no satisfaction history of the preceding condition, which is an entry condition of the preceding order even when the following condition, which is an entry condition of the following order, is satisfied; and delete and initialize the satisfaction history of the preceding condition in response that a state in which the following condition is not satisfied exceeds a set time in the state in which the satisfaction history of the preceding condition is present.
12 . The method of claim 1 , further including: determining, by the controller, whether a predetermined release condition for releasing the responsiveness priority mode is satisfied based on the vehicle driving information in a state in which the control of the responsiveness priority mode is performed; and transitioning, by the controller, the mode to the power priority mode in response that the release condition is satisfied and performing the control of the power priority mode.
13 . The method of claim 12 , wherein the vehicle driving information for determining whether the release condition of the responsiveness priority mode is satisfied includes an accelerator position input value and the entire torque command.
14 . The method of claim 13 , wherein the release condition of the responsiveness priority mode includes a condition in which the accelerator position input value is greater than a preset accelerator position input threshold and the entire torque command is greater than a preset release determination torque threshold.
15 . The method of claim 14 , wherein the release condition of the responsiveness priority mode further includes a condition in which a state in which the accelerator position input value is greater than the accelerator position input threshold and the entire torque command is greater than the release determination torque threshold is continuously maintained for a predetermined time period or longer than the predetermined time period.
16 . A vehicle of controlling a drive system torque of the vehicle, the vehicle comprising: a driving system including a driving device configured for driving front and rear wheels of the vehicle; and a controller configured for: determining an entire torque command required for travel of the vehicle; determining whether a plurality of predetermined entry conditions for entering a responsiveness priority mode of the vehicle are satisfied in a predetermined order based on vehicle driving information in a state in which control of a power priority mode in which front wheel torque control and rear wheel torque control are performed using a front wheel torque command and a rear wheel torque command respectively is performed; and transitioning a mode to the responsiveness priority mode in which the front wheel torque control and the rear wheel torque control are performed using the front wheel torque command and the rear wheel torque command for evading a backlash band, which is a torque region in which backlash of the drive system occurs, in response that the plurality of entry conditions are sequentially satisfied and performing control of the responsiveness priority mode, wherein the vehicle driving information for determining whether the plurality of entry conditions are satisfied includes a brake pedal position input value, a vehicle longitudinal acceleration, a steering wheel angle which is a steering input value, a vehicle transverse acceleration, the entire torque command, and an accelerator position input value, wherein the controller determines whether each of the plurality of entry conditions is satisfied based on a result of comparing each of the vehicle driving information with a respective preset threshold stored in a memory, and sequentially determines whether the entry conditions are satisfied in an order of a first entry condition, a second entry condition, and a third entry condition, wherein the plurality of entry conditions include: the first entry condition in which the brake pedal position input value is greater than a preset brake input threshold and an absolute value of the vehicle longitudinal acceleration is greater than a preset longitudinal acceleration threshold; the second entry condition in which the steering wheel angle is greater than a preset steering threshold and an absolute value of the vehicle transverse acceleration is greater than a preset transverse acceleration threshold; and the third entry condition in which there is no brake pedal position input or an absolute value of the entire torque command is smaller than a preset entry determination torque threshold.
17 . The vehicle of claim 16 , wherein in the performing of the control of the responsiveness priority mode, the front wheel torque command is determined to be a value which is smaller than or equal to a front wheel maximum torque threshold set to a negative (−) torque value, and the rear wheel torque command is determined to be a value which is greater than or equal to a rear wheel minimum torque threshold set to a positive (+) torque value.
18 . The vehicle of claim 16 , wherein the controller is further configured for: determining whether a predetermined release condition for releasing the responsiveness priority mode is satisfied based on the vehicle driving information in a state in which the control of the responsiveness priority mode is performed; and transitioning the mode to the power priority mode in response that the release condition is satisfied and performing the control of the power priority mode.

Description

CROSS-REFERENCE TO RELATED APPLICATION The present application claims priority to Korean Patent Application No. 10-2023-0066035 filed on May 23, 2023, the entire contents of which is incorporated herein for all purposes by this reference. BACKGROUND OF THE PRESENT DISCLOSURE Field of the Present Disclosure The present disclosure relates to a method of controlling a drive system torque of an electric vehicle, and more specifically, to a torque control method configured for generating a torque by evading a backlash band of a drive system in an electric vehicle. Description of Related art In general, a drive system of a vehicle should generate an appropriate torque according to a torque command determined based on a driving input value (e.g., an accelerator position input value or a brake pedal position input value) of a driver or a request of an advanced driver assistance system (ADAS). In the instant case, when a torque change rate is set too high, problems such as the torsion of a driveshaft, the strike of gear backlash, or the degradation of drivability caused by an impact due to rapidly changing torque occur. Conversely, when the torque change rate is limited too small, it takes an excessive time to provide a torque required by a driver or an ADAS controller, and an actual behavior of a vehicle may differ from the driver's intention, causing frustrating responsiveness or dangerous situations. As described above, a degree of a reduction in noise, vibration, and harshness (NVH) in the vehicle and a degree of securing the acceleration/deceleration responsiveness of the vehicle due to a rapid change in a torque have a trade-off relationship. In current mass-produced vehicles, slope limiting and filters using various conditions as factors are used to generate an optimal torque command capable of resolving the trade-off relationship. Furthermore, in electrified vehicles using a motor as a driving source or a part of the driving source, active feedback torque correction control capable of suppressing vibration, which has already occurred, using the motor is also applied in some cases. However, even when advanced backlash post-correction control is applied, it is difficult to suppress a problem of degrading vehicle responsiveness, which inevitably occurs chronically due to the characteristics of hardware. Moreover, the noise, vibration, and harshness (NVH) issues due to backlash frequently occur in electric vehicles with few vibration damping elements in the drive system. A related art discloses a method of generating a model speed of a driveshaft using a disturbance observer and reducing vibration using a deviation between the model speed and an actual speed of the driveshaft. In addition, a method of calculating the model speed based on a wheel speed instead of the disturbance observer in the method of determining the model speed is also disclosed. Furthermore, a related art discloses a method of generating a model speed of a motor using an input torque model and reducing vibration using a deviation between the model speed and an actual speed of the motor. Furthermore, a related art discloses a method of estimating a speed of a drive system using a torque model and determining a slope of a torque command using a speed difference between an actual speed and an estimated speed of a drive system. However, all of the related art only suggest a torque correction method for reducing and suppressing vibration generated in a drive system and do not suggest a torque determination method capable of preventing the occurrence of vibration itself Therefore, in relation to the backlash of the drive system, a control method capable of generating a torque command by evading a backlash band in which the backlash of the drive system may occur rather than a control method of solving the problem caused by the backlash is required. The information disclosed in this Background of the present disclosure is only for enhancement of understanding of the general background of the present disclosure and may not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. BRIEF SUMMARY Various aspects of the present disclosure are directed to providing a drive system torque command generation and torque control method, which may be configured to generate a torque by evading a backlash band to prevent the occurrence of backlash in a drive system. An object of the present disclosure is not limited to the above-described object, and other objects that are not mentioned will be able to be clearly understood by those skilled in the art to which the present disclosure pertains (hereinafter referred to as “those skilled in the art”) from the following description. An exemplary embodiment of the present disclosure provides a method of controlling a drive system torque of an electric vehicle including determining, by a controller, an entire torque command required f