Driving torque control method and system of vehicle

Abstract

The invention belongs to the technical field of automobile power control, and particularly discloses a driving torque control method and system of a vehicle. Comprising the steps of calculating an external characteristic torque according to an actual rotating speed of a four-wheel motor, and obtaining an intention torque by combining an accelerator opening; and generating a first limit and a second limit of the driving torque by taking the allowable discharge power of the power battery, the maximum power generation power of the range extender and the acceleration of the motor as constraints, and taking the minimum value of the three limits to obtain the expected execution torque. And then an ideal yaw velocity-side slip angle model is established, ideal deviation is calculated, a torque transfer coefficient is dynamically determined, and optimal distribution of four-wheel torque is achieved. And vehicle impact degree limitation is further introduced, first and second power variations of the vehicle are calculated in a layered manner, power change limitation is set in combination with the response capability of the range extender, and finally the single-wheel torque variation is calculated. According to the invention, the driving torque of the motor, the discharge power of the power battery and the generator power of the range extender are mutually coordinated, and the driving performance of the whole vehicle is improved.

Description

Technical Field

[0001] This invention belongs to the field of automotive power control technology, and more specifically, relates to a method and system for controlling the driving torque of a vehicle. Background Technology

[0002] With the rapid development of new energy vehicle technology, electric drive systems have gradually become a core component of the vehicle's powertrain. Especially in range-extended electric vehicles and pure electric four-wheel drive models, multi-motor distributed drive systems are widely used due to their advantages such as fast response, flexible control, and high energy efficiency. Distributed drive systems typically consist of multiple drive motors controlled independently, with each motor driving one wheel, enabling precise torque distribution and improving the vehicle's power, stability, and energy efficiency.

[0003] However, in actual operation, how to reasonably control the output torque of each drive motor to satisfy the driver's driving intentions while also taking into account the discharge capacity of the power battery, the power generation capacity of the range extender, and the dynamic response performance of the entire vehicle has become a key issue facing current technology. Traditional drive torque control methods often only consider the driver's throttle input, ignoring the instantaneous discharge capacity of the power battery, the power response capability of the range extender, and the limitations of the motor's external characteristics on the output torque. This can easily lead to problems such as over-discharge of the power battery, motor overload, large vehicle impact, and poor driving experience.

[0004] Furthermore, in-wheel motors or distributed drive vehicles represent a powertrain configuration for new energy vehicles. This configuration allows for independent torque control of each motor, improving vehicle stability and reducing turning radius, among other advantages. However, it also presents challenges such as increased control complexity. In particular, poor coordination between multiple motors, the power battery, and the range extender can lead to issues like over-discharge of the power battery or insufficient drive capability. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the prior art, the present invention provides a driving torque control method and system for vehicles, so as to solve the problem that the lack of coordination between multiple motors, power batteries and range extenders in multi-motor drive vehicles in the prior art leads to over-discharge of power batteries or insufficient driving capacity.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for controlling the driving torque of a vehicle is proposed, characterized by comprising the following steps: Step 1: Based on the actual rotational speed of the drive motor corresponding to the car wheel, calculate the external characteristic torque of the corresponding drive motor using the torque calculation formula. Calculate the intended torque of the corresponding drive motor based on the external characteristic torque of the corresponding drive motor and the accelerator pedal opening. Finally, calculate the intended driving torque based on the intended torque of the corresponding drive motor. Step 2: Calculate the first limit of drive torque based on the actual speed of the drive motor corresponding to the car wheel, the allowable discharge power of the power battery, and the maximum power generation of the range extender; Step 3: Calculate the second limit of drive torque based on the actual rotational speed of the drive motor corresponding to the car wheel, the acceleration of the corresponding drive motor, and the allowable discharge power of the power battery; Step 4: Calculate the desired drive torque based on the intended drive torque, the first drive torque limit, and the second drive torque limit; Step 5: Establish an ideal state calculation model based on the ideal yaw rate and the ideal center of mass sideslip angle, calculate the ideal deviation between the ideal state calculated by the ideal state calculation model and the actual state, and calculate the torque transfer coefficient based on the ideal deviation. Step 6: Calculate the desired drive torque allocation based on the torque transfer coefficient and the desired drive torque. Step 7: Calculate the vehicle torque variation limit based on the vehicle mass, wheel radius, and vehicle impact limit, and calculate the single-wheel torque variation limit based on the vehicle torque variation limit, and use this to calculate the first power change of the vehicle. Step 8: Calculate the second power change of the whole vehicle based on the single wheel torque change limit, the actual speed of the motor corresponding to the wheel, and the actual acceleration of the motor corresponding to the wheel; Step 9: Calculate the vehicle power change limit based on the first power change of the vehicle, the second power change of the vehicle, and the power response capability of the range extender during task execution time. Step 10: Calculate the change in torque of a single wheel based on the first change in vehicle power, the limit on the change in vehicle power, and the limit on the change in torque of a single wheel; Step 11: Calculate the smoothed torque of each wheel at the current moment based on the single wheel torque change, the expected drive torque, and the smoothed torque at the previous moment, and calculate the expected execution torque of the drive motor corresponding to the car wheel accordingly.

[0007] As a further preferred embodiment, in step one, the step of calculating the external characteristic torque of the corresponding drive motor based on the actual speed of the drive motor corresponding to the car wheel using the torque calculation formula includes: calculating the external characteristic torque of the left front drive motor, the external characteristic torque of the front drive motor, the external characteristic torque of the left rear drive motor, and the external characteristic torque of the right rear drive motor based on the relationship between the actual speed of the left front drive motor, the actual speed of the right front drive motor, the actual speed of the left rear drive motor, the actual speed of the right rear drive motor and the rated speed, respectively. The formulas for calculating the external characteristic torque of the left front drive motor, the right front drive motor, the left rear drive motor, and the right rear drive motor are as follows: , In the formula, The external characteristic torque of the left front drive motor; The external characteristic torque of the right front drive motor; The external characteristic torque of the left rear drive motor; This refers to the external characteristic torque of the right rear drive motor. This is the rated torque; Rated speed; This represents the actual speed of the left front drive motor. This represents the actual speed of the right front drive motor. This represents the actual speed of the left rear drive motor; This represents the actual speed of the right rear drive motor. As a further preferred embodiment, in step one, calculating the intended torque of the corresponding drive motor based on the external characteristic torque of the corresponding drive motor and the accelerator pedal opening includes: The intended torques of the left front drive motor, right front drive motor, left rear drive motor, and right rear drive motor are calculated based on the accelerator pedal opening, the external characteristic torque of the left front drive motor, the external characteristic torque of the right front drive motor, the external characteristic torque of the left rear drive motor, and the external characteristic torque of the right rear drive motor. Specifically, the intended torque of the left front drive motor is equal to the product of the accelerator pedal opening and the external characteristic torque of the left front drive motor; the intended torque of the right front drive motor is equal to the product of the accelerator pedal opening and the external characteristic torque of the right front drive motor; the intended torque of the left rear drive motor is equal to the product of the accelerator pedal opening and the external characteristic torque of the left rear drive motor; and the intended torque of the right rear drive motor is equal to the product of the accelerator pedal opening and the external characteristic torque of the right rear drive motor. As a further preferred embodiment, in step one, the intended driving torque is taken as the average value of the intended torques of the drive motors corresponding to all wheels of the vehicle.

[0008] As a further preferred embodiment, in step two, the calculation formula for the first limit of the driving torque includes: In the formula, This represents the actual speed of the left front drive motor. This represents the actual speed of the right front drive motor. This represents the actual speed of the left rear drive motor; This represents the actual speed of the right rear drive motor. As the first limit for driving torque, The allowable discharge power of the power battery. This represents the maximum power output of the range extender.

[0009] As a further preferred embodiment, in step three, the calculation formula for the second limit of the driving torque includes: In the formula, This represents the actual speed of the left front drive motor. This represents the actual speed of the right front drive motor. This represents the actual speed of the left rear drive motor; This represents the actual speed of the right rear drive motor. The allowable discharge power of the power battery. This is the maximum power output of the range extender. This is the actual acceleration of the left front drive motor. This represents the actual acceleration of the right front drive motor. This represents the actual acceleration of the left rear drive motor. This represents the actual acceleration of the right rear drive motor. For task execution time; Preferably, in step four, the desired driving torque is the minimum value among the intended driving torque, the first driving torque limit, and the second driving torque limit.

[0010] As a further preferred embodiment, in step five, the formula for the ideal state calculation model is: In the formula, The ideal yaw rate for the current state; The ideal yaw rate in the previous state; These are the weighting coefficients, and their calibration values. Here is the dimension conversion coefficient, the calibration value; The ideal centroid sideslip angle for the current state; This represents the sideslip angle of the ideal centroid in the previous state. These are the weighting coefficients, and their calibration values. Here is the dimension conversion coefficient, the calibration value; The steering wheel angle is detected and obtained by the steering wheel angle sensor. As a further preferred embodiment, the ideal deviation includes the ideal yaw rate deviation and the ideal centroid sideslip angle deviation, wherein the ideal yaw rate deviation is equal to the difference between the ideal yaw rate and the actual yaw rate; and the ideal centroid sideslip angle deviation is equal to the difference between the ideal centroid sideslip angle and the actual centroid sideslip angle. As a further preferred embodiment, the formula for calculating the torque transfer coefficient is: In the formula, The torque transfer coefficient, The conversion factor for ideal yaw rate. This is the coefficient for calculating the sideslip angle of the ideal centroid.

[0011] As a further preferred embodiment, in step six, the desired drive torque distribution includes: In the formula, Torque is expected to be distributed to the left front wheel drive; Torque is expected to be distributed to the right front wheel drive; Torque is expected to be distributed to the left rear-wheel drive; Torque is expected to be distributed to the right rear wheel drive; As a further preferred embodiment, in step seven, the calculation formula for the vehicle torque variation limit includes: In the formula, The limit is set for the overall vehicle torque variation; m is the overall vehicle mass; r is the wheel radius; j is the overall vehicle impact force limit. As a further preferred embodiment, the formula for calculating the first change in vehicle power includes: In the formula, This is the first change in the vehicle's power output. Limits the torque variation of a single wheel.

[0012] As a further preferred embodiment, in step eight, the formula for calculating the second power change of the vehicle includes: In the formula, This refers to the change in the vehicle's second power output. Preferably, in step ten, the limit for the change in vehicle power is the minimum value among the first change in vehicle power, the second change in vehicle power, and the power response capability of the range extender during task execution time. Preferably, in step eleven, the formula for calculating the change in torque of a single wheel includes: In the formula, This represents the change in torque of a single wheel. To limit the variation in vehicle power, To limit the torque variation of a single wheel, This represents the first change in the vehicle's power output.

[0013] Preferably, in step eleven, the formula for calculating the smoothing torque of each wheel at the current moment is: In the formula, The current left front smoothing torque; 𝑇3(K) 𝑓𝑟 The current right front smoothing torque; 𝑇3(K) 𝑟l The current left rear smoothing torque; 𝑇3(K) 𝑟𝑟 The current right rear smoothing torque; The left front smoothing torque at the previous moment; The smoothing torque of the right front at the previous moment; This represents the left rear smoothing torque from the previous moment; This represents the smoothing torque on the right rear at the previous moment.

[0014] Based on any of the above embodiments or combinations of embodiments, according to another aspect of the present invention, a vehicle drive torque control system is also provided, comprising: The first main control module is used to calculate the external characteristic torque of the corresponding drive motor according to the actual speed of the drive motor corresponding to the car wheel using the torque calculation formula, calculate the intended torque of the corresponding drive motor according to the external characteristic torque of the corresponding drive motor and the accelerator pedal opening, and calculate the driving intention torque according to the intended torque of the corresponding drive motor. The second main control module is used to calculate the first limit of drive torque based on the actual speed of the drive motor corresponding to the car wheel, the allowable discharge power of the power battery, and the maximum power generation of the range extender. The third main control module is used to calculate the second limit of drive torque based on the actual speed of the drive motor corresponding to the car wheel, the acceleration of the drive motor, and the allowable discharge power of the power battery. The fourth main control module is used to calculate the desired drive torque based on the intended drive torque, the first drive torque limit, and the second drive torque limit. The fifth main control module is used to establish an ideal state calculation model based on the ideal yaw rate and the ideal center of mass sideslip angle, and to calculate the ideal deviation between the ideal state calculated by the ideal state calculation model and the actual state, and to calculate the torque transfer coefficient based on the ideal deviation. The sixth main control module is used to calculate the desired drive torque based on the torque transfer coefficient and the desired drive torque. The seventh main control module is used to calculate the torque variation limit of the whole vehicle based on the whole vehicle mass, wheel radius, and whole vehicle impact limit, and to calculate the torque variation limit of a single wheel based on the torque variation limit of the whole vehicle, and to calculate the first power change of the whole vehicle based on this. The eighth main control module is used to calculate the second power change of the whole vehicle based on the single wheel torque change limit, the actual speed of the motor corresponding to the wheel, and the actual acceleration of the motor corresponding to the wheel. The ninth main control module is used to calculate the vehicle power change limit based on the first power change of the vehicle, the second power change of the vehicle, and the power response capability of the range extender task execution time. The tenth main control module is used to calculate the change in torque of a single wheel based on the first change in the vehicle's power, the limit on the change in the vehicle's power, and the limit on the change in the torque of a single wheel. The eleventh main control module is used to calculate the smoothed torque of each wheel at the current moment based on the single wheel torque change, the expected drive torque, and the smoothed torque of the previous moment, and to calculate the expected execution torque of the drive motor corresponding to the car wheel.

[0015] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages: 1. Based on the capacity constraints of the power battery and the range extender, this invention achieves coordination between the driving torque of the motor, the discharge power of the power battery, and the generator power of the range extender, thereby avoiding the problems of over-discharge of the power battery or insufficient driving capacity of the vehicle and improving the overall driving performance of the vehicle.

[0016] 2. This invention uses a triple nested constraint of "driving intention - power boundary - impact" to ensure the driver's power expectations while incorporating the external characteristics of the power battery, range extender and motor into a unified constraint in real time. This avoids energy waste caused by power fluctuations and ensures that the electric drive system always operates in a high-efficiency zone.

[0017] 3. This invention utilizes the dual-variable deviation of ideal yaw rate / center of gravity sideslip angle to dynamically calculate the torque transfer coefficient and instantaneously redistribute the desired torque to the four wheels, making the yaw response of the vehicle closer to neutral steering when the vehicle is on low-adhesion, open road, or changing lanes at high speed. After superimposing impact limiting and smoothing filtering, the longitudinal impact is reduced, significantly suppressing the "jumping" and "tail swing" phenomena, thus balancing handling stability and ride comfort.

[0018] 4. The layered limitation of this invention (first / second power change, range extender response capability, single wheel torque change) constrains the rate of increase of battery peak discharge, motor peak torque and transmission system peak torque within the tolerance range of the components, avoiding overcurrent, overtorsion and mechanical shock. Attached Figure Description

[0019] Figure 1 This is a flowchart of a vehicle drive torque control method according to an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0021] like Figure 1 As shown in the figure, an embodiment of the present invention provides a method for controlling the driving torque of a vehicle, comprising the following steps: Step 1: Calculate the external characteristic torque of the left front drive motor, the right front drive motor, the left rear drive motor, and the right rear drive motor based on their actual speeds. When the actual speed of the left front drive motor is less than or equal to its rated speed, the external characteristic torque of the left front drive motor is equal to its rated torque; when the actual speed of the left front drive motor is greater than its rated speed, the external characteristic torque of the left front drive motor is equal to 9550 multiplied by the rated power divided by the actual speed of the left front drive motor. Similarly, when the actual speed of the right front drive motor is less than or equal to its rated speed, the external characteristic torque of the right front drive motor is equal to its rated torque; when the actual speed of the right front drive motor is greater than its rated speed, the external characteristic torque of the right front drive motor is equal to 9550 multiplied by the rated power divided by the actual speed of the right front drive motor. Likewise, when the actual speed of the left rear drive motor is less than or equal to its rated speed, the external characteristic torque of the left rear drive motor is equal to its rated torque; when the actual speed of the left rear drive motor is greater than its rated speed, the external characteristic torque of the left rear drive motor is equal to 9550 multiplied by the rated power divided by the actual speed of the left rear drive motor. The formulas for calculating the external characteristic torque of the left front drive motor, the right front drive motor, the left rear drive motor, and the right rear drive motor are as follows: in: The external characteristic torque of the left front drive motor; The external characteristic torque of the right front drive motor; The external characteristic torque of the left rear drive motor; This refers to the external characteristic torque of the right rear drive motor. Given the rated torque and fixed parameters; The rated speed is a known fixed value; The actual speed of the left front drive motor is obtained through a speed sensor; The actual speed of the right front drive motor is obtained through a speed sensor; The actual speed of the left rear drive motor is obtained through a speed sensor. The actual speed of the right rear drive motor is obtained through a speed sensor.

[0022] Step 2: Calculate the intended torques of the left front drive motor, right front drive motor, left rear drive motor, and right rear drive motor based on the accelerator pedal opening, the external characteristic torque of the left front drive motor, the external characteristic torque of the right front drive motor, the external characteristic torque of the left rear drive motor, and the external characteristic torque of the right rear drive motor. The intended torque of the left front drive motor is equal to the product of the accelerator pedal opening and the external characteristic torque of the left front drive motor; the intended torque of the right front drive motor is equal to the product of the accelerator pedal opening and the external characteristic torque of the right front drive motor; the intended torque of the left rear drive motor is equal to the product of the accelerator pedal opening and the external characteristic torque of the left rear drive motor; the intended torque of the right rear drive motor is equal to the product of the accelerator pedal opening and the external characteristic torque of the right rear drive motor. The formulas for calculating the intended torques of the left front drive motor, right front drive motor, left rear drive motor, and right rear drive motor are as follows: in, The intended torque for the left front drive motor; The intended torque for the right front drive motor; The intended torque for the left rear drive motor; The intended torque for the right rear drive motor; This refers to the accelerator pedal opening.

[0023] Step 3: Calculate the intended drive torque based on the intended torques of the left front drive motor, right front drive motor, left rear drive motor, and right rear drive motor. The intended drive torque is equal to the sum of the intended torques of the left front drive motor, right front drive motor, left rear drive motor, and right rear drive motor, divided by 4.

[0024] in: The intended torque is for driving.

[0025] Step 4: Calculate the first limit of drive torque based on the actual speeds of the left front drive motor, right front drive motor, left rear drive motor, right rear drive motor, the allowable discharge power of the power battery, and the maximum power output of the range extender. The first limit of drive torque is equal to the reciprocal of the sum of the actual speeds of the left front drive motor, right front drive motor, left rear drive motor, and right rear drive motor, multiplied by 9550, and then multiplied by the sum of the allowable discharge power of the power battery and the maximum power output of the range extender. The formula for calculating the first limit of drive torque is: In the formula, This represents the actual speed of the left front drive motor. This represents the actual speed of the right front drive motor. This represents the actual speed of the left rear drive motor; This represents the actual speed of the right rear drive motor. As the first limit for driving torque, The allowable discharge power of the power battery. This represents the maximum power output of the range extender. Step 5: Calculate the actual accelerations of the left front drive motor, right front drive motor, left rear drive motor, and right rear drive motor based on their actual speeds. The actual accelerations of these motors are equal to the derivatives of their respective speeds. The formulas for calculating the actual accelerations of the left front drive motor, right front drive motor, left rear drive motor, and right rear drive motor are as follows: in: This represents the actual acceleration of the left front drive motor. This represents the actual acceleration of the right front drive motor. This represents the actual acceleration of the left rear drive motor. This represents the actual acceleration of the right rear drive motor.

[0026] Step 6: Calculate the second limit of drive torque based on the actual acceleration of the left front drive motor, the actual acceleration of the right front drive motor, the actual acceleration of the left rear drive motor, the actual acceleration of the right rear drive motor, the actual speed of the left front drive motor, the actual speed of the right front drive motor, the actual speed of the left rear drive motor, the actual speed of the right rear drive motor, and the allowable discharge power of the power battery. The second limit of drive torque is equal to the sum of the products of the actual acceleration of the left front drive motor, the right front drive motor, the left rear drive motor, and the right rear drive motor and the task execution time, plus the reciprocal of the sum of the actual speeds of the left front drive motor, the right front drive motor, the left rear drive motor, and the right rear drive motor, multiplied by 9550, and then multiplied by the sum of the allowable discharge power of the power battery and the maximum power output of the range extender. The formula for calculating the second limit of drive torque is: This represents the actual speed of the left front drive motor. This represents the actual speed of the right front drive motor. This represents the actual speed of the left rear drive motor; This represents the actual speed of the right rear drive motor. The allowable discharge power of the power battery. This is the maximum power output of the range extender. This is the actual acceleration of the left front drive motor. This represents the actual acceleration of the right front drive motor. This represents the actual acceleration of the left rear drive motor. This represents the actual acceleration of the right rear drive motor. This refers to the task execution time.

[0027] Step 7: Calculate the desired drive torque based on the intended drive torque, the first drive torque limit, and the second drive torque limit. The desired drive torque is equal to the minimum value among the intended drive torque, the first drive torque limit, and the second drive torque limit. The formula for calculating the desired drive torque is: in: To drive the desired torque.

[0028] Step 8: Establish the ideal state calculation model. The ideal state includes: ideal yaw rate and ideal sideslip angle. The formula for the ideal state calculation model is: in: Ideal yaw rate in the current state; The ideal yaw rate in the previous state; Weighting coefficients, calibration values; Dimensional conversion factor, calibration value; The current ideal centroid sideslip angle; The ideal centroid sideslip angle in the previous state; Weighting coefficients, calibration values; Dimensional conversion factor, calibration value; The steering wheel angle is detected and obtained by the steering wheel angle sensor.

[0029] Step 9: Calculate the ideal deviation based on the ideal and actual states. The ideal deviation includes the ideal yaw rate deviation and the ideal center-of-mass sideslip angle deviation. The ideal yaw rate deviation is equal to the difference between the ideal yaw rate and the actual yaw rate; the ideal center-of-mass sideslip angle deviation is equal to the difference between the ideal center-of-mass sideslip angle and the actual center-of-mass sideslip angle. The formula for calculating the ideal deviation is: in: The deviation from the ideal yaw rate; The deviation of the ideal centroid sideslip angle. The actual yaw rate is the value detected by the sensor. This is the actual centroid sideslip angle, as detected by the sensor.

[0030] Step 10: Calculate the torque transfer coefficient based on the ideal deviation. The torque transfer coefficient is equal to the product of the ideal yaw rate deviation and the ideal yaw rate reduction coefficient, plus the product of the ideal center-of-gravity sideslip angle deviation and the ideal center-of-gravity sideslip angle reduction coefficient. The formula for calculating the torque transfer coefficient is: in: The torque transfer coefficient is in the range of [-1, 1]. The ideal yaw rate conversion factor, the calibration value; The ideal centroid sideslip angle reduction factor is the calibration value.

[0031] Step 11: Calculate the expected drive distribution torque based on the torque transfer coefficient and the expected drive execution torque. The expected drive distribution torque includes the expected distribution torques for the left front wheel, right front wheel, left rear wheel, and right rear wheel. The expected distribution torques for the left front and left rear wheels are both equal to 1, multiplied by the sum of the torque transfer coefficient and the expected drive execution torque; the expected distribution torques for the right front and right rear wheels are both equal to 1, multiplied by the difference of the torque transfer coefficient and the expected drive execution torque. The calculation formulas for the expected distribution torques for the left front, right front, left rear, and right rear wheels are as follows: in: Torque is expected to be distributed to the left front wheel drive; Torque is expected to be distributed to the right front wheel drive; Torque is expected to be distributed to the left rear-wheel drive; Torque is expected to be distributed to the right rear wheel drive.

[0032] Step 12: Calculate the vehicle torque variation limit based on the vehicle mass, wheel radius, and vehicle impact limit. The vehicle torque variation limit is equal to the product of the vehicle mass, wheel radius, and vehicle impact limit. The formula for calculating the vehicle torque variation limit is: in: The limit is the torque variation of the whole vehicle; m is the mass of the whole vehicle; r is the wheel radius; j is the impact limit of the whole vehicle.

[0033] Step 13: Calculate the single-wheel torque variation limit based on the overall vehicle torque variation limit. The single-wheel torque variation limit is equal to the overall vehicle torque variation limit divided by 4. Here, 4 represents the number of drive wheels. The formula for calculating the single-wheel torque variation limit is: in: Limits the torque variation of a single wheel.

[0034] Step 14: Calculate the first power change of the vehicle based on the single-wheel torque variation limit, the actual speeds of the left front drive motor, the right front drive motor, the left rear drive motor, and the right rear drive motor. The first power change of the vehicle is equal to the sum of the actual speeds of the left front drive motor, the right front drive motor, the left rear drive motor, and the right rear drive motor, multiplied by the single-wheel torque variation limit, and then divided by 9550. The formula for calculating the first power change of the vehicle is: in: This is the first change in the vehicle's power output. Limits the torque variation of a single wheel.

[0035] Step 15: Calculate the second power change of the vehicle based on the single-wheel torque variation limit, the actual speeds of the left front drive motor, right front drive motor, left rear drive motor, right rear drive motor, actual acceleration of the left front drive motor, right front drive motor, left rear drive motor, and right rear drive motor. The second power change of the vehicle is equal to the sum of the product of the actual acceleration of each drive motor and the task execution time, the actual speeds of the left front drive motor, right front drive motor, left rear drive motor, and right rear drive motor, multiplied by the single-wheel torque variation limit, and then divided by 9550. The formula for calculating the second power change of the vehicle is: in: This represents the second change in vehicle power.

[0036] Step 16: Calculate the vehicle power variation limit based on the first change in vehicle power, the second change in vehicle power, and the power response capability of the range extender during task execution time. The vehicle power variation limit is equal to the smaller value among the first change in vehicle power, the second change in vehicle power, and the power response capability of the range extender during task execution time. The formula for calculating the vehicle power variation limit is: in: To limit the variation in vehicle power; To determine the power response capability of the range extender during task execution, bench tests were conducted to obtain parameters.

[0037] Step 17: Calculate the single-wheel torque change based on the first change in vehicle power, the vehicle power change limit, and the single-wheel torque change limit. The single-wheel torque change equals the vehicle power change limit multiplied by the vehicle power change amount multiplied by the single-wheel torque change limit.

[0038] in: This represents the change in torque of a single wheel. To limit the variation in vehicle power, To limit the torque variation of a single wheel, This represents the first change in the vehicle's power output.

[0039] Step 18: Calculate the smoothed torque of each wheel at the current moment based on the single-wheel torque change, the expected torque distribution for the left front wheel drive, the expected torque distribution for the right front wheel drive, the expected torque distribution for the left rear wheel drive, the expected torque distribution for the right rear wheel drive, and the smoothed torque from the previous moment. When the difference between the smoothed torque of each wheel from the previous moment and the expected torque distribution for that wheel is greater than the single-wheel torque change, the smoothed torque of that wheel at the current moment is equal to the smoothed torque of that wheel from the previous moment minus the single-wheel torque change. When the difference between the smoothed torque of that wheel from the previous moment and the expected torque distribution for that wheel is less than the negative of the single-wheel torque change, the smoothed torque of that wheel at the current moment is equal to the smoothed torque of that wheel from the previous moment plus the single-wheel torque change. When the difference between the smoothed torque of that wheel from the previous moment and the expected torque distribution for that wheel is neither greater than the single-wheel torque change nor less than the negative of the single-wheel torque change, the smoothed torque of that wheel at the current moment is equal to the expected torque distribution for that wheel. The formula for calculating the smoothed torque of each wheel at the current moment is: in: The current left front smoothing torque; 𝑇3(K) 𝑓𝑟 The current right front smoothing torque; 𝑇3(K) 𝑟l The current left rear smoothing torque; 𝑇3(K) 𝑟𝑟 The current right rear smoothing torque; The left front smoothing torque at the previous moment; The smoothing torque of the right front at the previous moment; This represents the left rear smoothing torque from the previous moment; This represents the smoothing torque on the right rear at the previous moment.

[0040] Furthermore, the left front wheel drive motor, right front wheel drive motor, left rear wheel drive motor, and right rear wheel drive motor are controlled to execute according to the current smooth torque of the left front wheel, the current smooth torque of the right front wheel, the current smooth torque of the left rear wheel, and the current smooth torque of the right rear wheel.

[0041] Based on any of the above embodiments or combinations of embodiments, according to another aspect of the present invention, a vehicle drive torque control system is also provided for executing any of the above methods, including: The first main control module is used to calculate the external characteristic torque of the corresponding drive motor according to the actual speed of the drive motor corresponding to the car wheel using the torque calculation formula, calculate the intended torque of the corresponding drive motor according to the external characteristic torque of the corresponding drive motor and the accelerator pedal opening, and calculate the driving intention torque according to the intended torque of the corresponding drive motor. The second main control module is used to calculate the first limit of drive torque based on the actual speed of the drive motor corresponding to the car wheel, the allowable discharge power of the power battery, and the maximum power generation of the range extender. The third main control module is used to calculate the second limit of drive torque based on the actual speed of the drive motor corresponding to the car wheel, the acceleration of the drive motor, and the allowable discharge power of the power battery. The fourth main control module is used to calculate the desired drive torque based on the intended drive torque, the first drive torque limit, and the second drive torque limit. The fifth main control module is used to establish an ideal state calculation model based on the ideal yaw rate and the ideal center of mass sideslip angle, and to calculate the ideal deviation between the ideal state calculated by the ideal state calculation model and the actual state, and to calculate the torque transfer coefficient based on the ideal deviation. The sixth main control module is used to calculate the desired drive torque based on the torque transfer coefficient and the desired drive torque. The seventh main control module is used to calculate the torque variation limit of the whole vehicle based on the whole vehicle mass, wheel radius, and whole vehicle impact limit, and to calculate the torque variation limit of a single wheel based on the torque variation limit of the whole vehicle, and to calculate the first power change of the whole vehicle based on this. The eighth main control module is used to calculate the second power change of the whole vehicle based on the single wheel torque change limit, the actual speed of the motor corresponding to the wheel, and the actual acceleration of the motor corresponding to the wheel. The ninth main control module is used to calculate the vehicle power change limit based on the first power change of the vehicle, the second power change of the vehicle, and the power response capability of the range extender task execution time. The tenth main control module is used to calculate the change in torque of a single wheel based on the first change in the vehicle's power, the limit on the change in the vehicle's power, and the limit on the change in the torque of a single wheel. The eleventh main control module is used to calculate the smoothed torque of each wheel at the current moment based on the single wheel torque change, the expected drive torque, and the smoothed torque of the previous moment, and to calculate the expected execution torque of the drive motor corresponding to the car wheel.

[0042] Based on the capacity constraints of the power battery and the range extender, this invention achieves coordination between the driving torque of the motor, the discharge power of the power battery, and the generator power of the range extender, thereby avoiding the problems of over-discharge of the power battery or insufficient driving capacity of the vehicle and improving the overall driving performance of the vehicle.

[0043] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling the driving torque of a vehicle, characterized in that, Includes the following steps: Step 1: Based on the actual rotational speed of the drive motor corresponding to the car wheel, calculate the external characteristic torque of the corresponding drive motor using the torque calculation formula. Calculate the intended torque of the corresponding drive motor based on the external characteristic torque of the corresponding drive motor and the accelerator pedal opening. Finally, calculate the intended driving torque based on the intended torque of the corresponding drive motor. Step 2: Calculate the first limit of drive torque based on the actual speed of the drive motor corresponding to the car wheel, the allowable discharge power of the power battery, and the maximum power generation of the range extender; Step 3: Calculate the second limit of drive torque based on the actual rotational speed of the drive motor corresponding to the car wheel, the acceleration of the corresponding drive motor, and the allowable discharge power of the power battery; Step 4: Calculate the desired drive torque based on the intended drive torque, the first drive torque limit, and the second drive torque limit; Step 5: Establish an ideal state calculation model based on the ideal yaw rate and the ideal center of mass sideslip angle, calculate the ideal deviation between the ideal state calculated by the ideal state calculation model and the actual state, and calculate the torque transfer coefficient based on the ideal deviation. Step 6: Calculate the desired drive torque allocation based on the torque transfer coefficient and the desired drive torque. Step 7: Calculate the vehicle torque variation limit based on the vehicle mass, wheel radius, and vehicle impact limit, and calculate the single-wheel torque variation limit based on the vehicle torque variation limit, and use this to calculate the first power change of the vehicle. Step 8: Calculate the second power change of the whole vehicle based on the single wheel torque change limit, the actual speed of the motor corresponding to the wheel, and the actual acceleration of the motor corresponding to the wheel; Step 9: Calculate the vehicle power change limit based on the first power change of the vehicle, the second power change of the vehicle, and the power response capability of the range extender during task execution time. Step 10: Calculate the change in torque of a single wheel based on the first change in vehicle power, the limit on the change in vehicle power, and the limit on the change in torque of a single wheel; Step 11: Calculate the smoothed torque of each wheel at the current moment based on the single wheel torque change, the expected drive torque, and the smoothed torque at the previous moment, and calculate the expected execution torque of the drive motor corresponding to the car wheel accordingly.

2. The vehicle drive torque control method according to claim 1, characterized in that, In step one, the step of calculating the external characteristic torque of the corresponding drive motor based on the actual speed of the drive motor corresponding to the car wheel using the torque calculation formula includes: calculating the external characteristic torque of the left front drive motor, the external characteristic torque of the front drive motor, the external characteristic torque of the left rear drive motor, and the external characteristic torque of the right rear drive motor based on the relationship between the actual speed of the left front drive motor, the actual speed of the right front drive motor, the actual speed of the left rear drive motor, the actual speed of the right rear drive motor and the rated speed, respectively. The formulas for calculating the external characteristic torque of the left front drive motor, the right front drive motor, the left rear drive motor, and the right rear drive motor are as follows: ， In the formula, The external characteristic torque of the left front drive motor; The external characteristic torque of the right front drive motor; The external characteristic torque of the left rear drive motor; This refers to the external characteristic torque of the right rear drive motor. This is the rated torque; Rated speed; This represents the actual speed of the left front drive motor. This represents the actual speed of the right front drive motor. This represents the actual speed of the left rear drive motor; This represents the actual speed of the right rear drive motor.

3. The vehicle drive torque control method according to claim 2, characterized in that, In step one, calculating the intended torque of the corresponding drive motor based on the external characteristic torque of the corresponding drive motor and the accelerator pedal opening includes: The intended torques of the left front drive motor, right front drive motor, left rear drive motor, and right rear drive motor are calculated based on the accelerator pedal opening, the external characteristic torque of the left front drive motor, the external characteristic torque of the right front drive motor, the external characteristic torque of the left rear drive motor, and the external characteristic torque of the right rear drive motor. Specifically, the intended torque of the left front drive motor is equal to the product of the accelerator pedal opening and the external characteristic torque of the left front drive motor; the intended torque of the right front drive motor is equal to the product of the accelerator pedal opening and the external characteristic torque of the right front drive motor; the intended torque of the left rear drive motor is equal to the product of the accelerator pedal opening and the external characteristic torque of the left rear drive motor; and the intended torque of the right rear drive motor is equal to the product of the accelerator pedal opening and the external characteristic torque of the right rear drive motor. In step one, the intended driving torque is taken as the average value of the intended torque of the drive motors corresponding to all wheels of the car.

4. The vehicle drive torque control method according to claim 1, characterized in that, In step two, the calculation formula for the first limit of the driving torque is... include: ， In the formula, This represents the actual speed of the left front drive motor. This represents the actual speed of the right front drive motor. This represents the actual speed of the left rear drive motor; This represents the actual speed of the right rear drive motor. As the first limit for driving torque, The allowable discharge power of the power battery. This represents the maximum power output of the range extender.

5. The vehicle drive torque control method according to claim 1, characterized in that, In step three, the calculation formula for the second limit of the driving torque includes: ， In the formula, This represents the actual speed of the left front drive motor. This represents the actual speed of the right front drive motor. This represents the actual speed of the left rear drive motor; This represents the actual speed of the right rear drive motor. The allowable discharge power of the power battery. This is the maximum power output of the range extender. This is the actual acceleration of the left front drive motor. This represents the actual acceleration of the right front drive motor. This represents the actual acceleration of the left rear drive motor. This represents the actual acceleration of the right rear drive motor. This refers to the task execution time.

6. The vehicle drive torque control method according to claim 1, characterized in that, In step four, the desired driving torque is the minimum value among the intended driving torque, the first driving torque limit, and the second driving torque limit.

7. The method for controlling the driving torque of a vehicle according to claim 1, characterized in that, In step five, the formula for the ideal state calculation model is: ， In the formula, The ideal yaw rate for the current state; The ideal yaw rate in the previous state; These are the weighting coefficients, and their calibration values. Here is the dimension conversion coefficient, the calibration value; The ideal centroid sideslip angle for the current state; This represents the sideslip angle of the ideal centroid in the previous state. These are the weighting coefficients, and their calibration values. Here is the dimension conversion coefficient, the calibration value; The steering wheel angle is detected and obtained by the steering wheel angle sensor. The ideal deviation includes the ideal yaw rate deviation and the ideal center of mass sideslip angle deviation, wherein the ideal yaw rate deviation is equal to the difference between the ideal yaw rate and the actual yaw rate; and the ideal center of mass sideslip angle deviation is equal to the difference between the ideal center of mass sideslip angle and the actual center of mass sideslip angle. The formula for calculating the torque transfer coefficient is as follows: ， In the formula, The torque transfer coefficient, The conversion factor for ideal yaw rate. This is the coefficient for calculating the sideslip angle of the ideal centroid.

8. The method for controlling the driving torque of a vehicle according to claim 1, characterized in that, In step six, the desired drive torque distribution includes: ， In the formula, Torque is expected to be distributed to the left front wheel drive; Torque is expected to be distributed to the right front wheel drive; Torque is expected to be distributed to the left rear-wheel drive; Torque is expected to be distributed to the right rear wheel drive. To drive the desired torque; In step seven, the calculation formula for the vehicle torque variation limit includes: ， In the formula, The limit is set for the overall vehicle torque variation; m is the overall vehicle mass; r is the wheel radius; j is the overall vehicle impact force limit. The formula for calculating the first change in vehicle power includes: ， In the formula, This is the first change in the vehicle's power output. Limits the torque variation of a single wheel.

9. The method for controlling the driving torque of a vehicle according to claim 1, characterized in that, In step eight, the calculation formula for the second power change of the vehicle includes: ， In the formula, This refers to the change in the vehicle's second power output. Preferably, in step ten, the limit for the change in vehicle power is the minimum value among the first change in vehicle power, the second change in vehicle power, and the power response capability of the range extender during task execution time. Preferably, in step eleven, the formula for calculating the change in torque of a single wheel includes: ， In the formula, This represents the change in torque of a single wheel. To limit the variation in vehicle power, To limit the torque variation of a single wheel, This is the first change in the vehicle's power output; Preferably, in step eleven, the formula for calculating the smoothing torque of each wheel at the current moment is: ， In the formula, The current left front smoothing torque; 𝑇3(K) 𝑓𝑟 The current right front smoothing torque; 𝑇3(K) 𝑟l The current left rear smoothing torque; 𝑇3(K) 𝑟𝑟 The current right rear smoothing torque, The left front smoothing torque at the previous moment; The smoothing torque of the right front at the previous moment; This represents the left rear smoothing torque from the previous moment; This represents the smoothing torque on the right rear at the previous moment.

10. A drive torque control system for a vehicle, characterized in that, include: The first main control module is used to calculate the external characteristic torque of the corresponding drive motor according to the actual speed of the drive motor corresponding to the car wheel using the torque calculation formula, calculate the intended torque of the corresponding drive motor according to the external characteristic torque of the corresponding drive motor and the accelerator pedal opening, and calculate the driving intention torque according to the intended torque of the corresponding drive motor. The second main control module is used to calculate the first limit of drive torque based on the actual speed of the drive motor corresponding to the car wheel, the allowable discharge power of the power battery, and the maximum power generation of the range extender. The third main control module is used to calculate the second limit of drive torque based on the actual speed of the drive motor corresponding to the car wheel, the acceleration of the drive motor, and the allowable discharge power of the power battery. The fourth main control module is used to calculate the desired drive torque based on the intended drive torque, the first drive torque limit, and the second drive torque limit. The fifth main control module is used to establish an ideal state calculation model based on the ideal yaw rate and the ideal center of mass sideslip angle, and to calculate the ideal deviation between the ideal state calculated by the ideal state calculation model and the actual state, and to calculate the torque transfer coefficient based on the ideal deviation. The sixth main control module is used to calculate the desired drive torque based on the torque transfer coefficient and the desired drive torque. The seventh main control module is used to calculate the torque variation limit of the whole vehicle based on the whole vehicle mass, wheel radius, and whole vehicle impact limit, and to calculate the torque variation limit of a single wheel based on the torque variation limit of the whole vehicle, and to calculate the first power change of the whole vehicle based on this. The eighth main control module is used to calculate the second power change of the whole vehicle based on the single wheel torque change limit, the actual speed of the motor corresponding to the wheel, and the actual acceleration of the motor corresponding to the wheel. The ninth main control module is used to calculate the vehicle power change limit based on the first power change of the vehicle, the second power change of the vehicle, and the power response capability of the range extender task execution time. The tenth main control module is used to calculate the change in torque of a single wheel based on the first change in the vehicle's power, the limit on the change in the vehicle's power, and the limit on the change in the torque of a single wheel. The eleventh main control module is used to calculate the smoothed torque of each wheel at the current moment based on the single wheel torque change, the expected drive torque, and the smoothed torque of the previous moment, and to calculate the expected execution torque of the drive motor corresponding to the car wheel.

Images