CN115230700A - Pure electric vehicle drive anti-skid control method and system - Google Patents

Abstract

The invention discloses a pure electric vehicle drive anti-skid control method and a system, comprising the following steps: the target limit control layer acquires the speed of a vehicle wheel and the steering wheel angle at the current moment, and determines a driving shaft speed limit value according to the speed of the vehicle wheel and the steering wheel angle; when the vehicle is in a transient working condition of wheel slip, the high-frequency control layer calculates a motor rotating speed limit value according to the driving shaft speed limit value, calculates a torque limit value according to the motor rotating speed limit value, and controls the output torque of a vehicle driving motor according to the torque limit value; the TCS in the low frequency control layer ESP controls the output torque of the vehicle drive motor when in a steady state condition of wheel slip.

Description

A kind of pure electric drive vehicle driving anti-skid control method and system

technical field

The invention relates to the technical field of vehicle driving anti-skid driving, in particular to a pure electric driving vehicle driving anti-skid control method and system.

Background technique

In the traditional traditional driving anti-skid control function (TCS for short), the body electronic stability system (ESP) calculates the slip rate according to the driving wheel speed and the reference vehicle speed, and sends it to the vehicle controller (VCU for short) and the transmission control unit (DCU for short). A torque control request is sent to control the slip ratio near the target value. In addition, while the torque intervention is performed by the separate road ESP, the braking control of the low-side wheels is also performed to control the wheel speed difference near the target value. , the main problems are that the torque control link is long, the control delay is large, and there is a certain delay in the activation and withdrawal of the TCS function.

However, there is a big difference in the dynamic characteristics of the drive system between pure electric vehicles and traditional vehicles. Compared with traditional engines, the drive motor has large low-speed torque, fast torque response, small moment of inertia, and high rotational speed. These differences in characteristics lead to the TCS function in traditional ESP. When applied to pure electric drive vehicles, when the wheels of pure electric drive vehicles slip, the TCS function cannot quickly intervene in torque, the wheel speed and motor speed rise rapidly, and the drive anti-skid control performance is poor, which may easily lead to the following problems: For example, low adhesion At the moment of starting on the road, the wheel speed soars too high, which affects safety and comfort. At the same time, at the moment of starting, due to the rapid increase of the motor speed, the power consumption rises rapidly, which can easily lead to overcurrent of the battery; When the side high attachment) starts, the wheel speed on the low attachment side will rise too high, which will cause the start to sway, and will also affect the life of the differential. When the wheel goes from a low adhesion road to a high adhesion road, it will have a big impact.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method and system for driving anti-skid control of a pure electric vehicle, and a computer-readable storage medium, so as to solve the technical problem of poor anti-skid control performance when the TCS in the traditional ESP is applied to a pure electric vehicle.

In order to achieve the above purpose, the first aspect of the present invention provides a driving anti-skid control method for a pure electric drive vehicle, including:

The target limit control layer obtains the vehicle wheel speed and the steering wheel angle at the current moment, and determines the drive shaft speed limit according to the vehicle wheel speed and the steering wheel angle;

When in the transient condition of wheel slip, the high-frequency control layer calculates the motor speed limit according to the drive shaft shaft speed limit, calculates the torque limit according to the motor speed limit, and calculates the torque limit according to the torque limit Control the output torque of the vehicle drive motor;

When in the steady state of wheel slippage, the low-frequency control layer controls the output torque of the vehicle drive motor based on the TCS in the ESP.

Optionally, the determining the drive shaft speed limit value according to the vehicle wheel speed and the steering wheel angle specifically includes:

Calculate a reference vehicle speed according to the vehicle wheel speed, and calculate a reference axle speed according to the reference vehicle speed and the steering wheel angle;

Obtain the shaft speed offset value according to the reference shaft quick look-up table, and obtain the basic shaft speed limit value according to the reference shaft speed and shaft speed offset value;

Calculate the wheel speed difference between the left and right driving wheels of the vehicle and take the absolute value to obtain the wheel speed difference, and modify the basic axle speed limit according to the wheel speed difference to obtain the drive axle axle speed limit.

Optionally, obtaining the drive shaft shaft speed limit by modifying the basic axle speed limit according to the wheel speed difference includes:

Obtain the corresponding dead zone threshold according to the reference vehicle speed look-up table, determine whether the wheel speed difference is greater than the dead zone threshold, if it is greater than the dead zone threshold, perform wheel speed difference correction, if it is less than the dead zone threshold, do not correct the wheel speed difference;

When the wheel speed difference is corrected, if the wheel speed difference increases, the wheel speed difference is multiplied by a preset correction coefficient to obtain the initial correction value of the wheel speed difference, and the preset correction coefficient takes a value of 0 to 1; if the wheel speed difference decreases, Then, the drop delay processing is performed on the wheel speed difference to obtain the initial correction value of the wheel speed difference;

Obtain the final wheel speed difference correction value according to the preset wheel speed difference limit value and the wheel speed difference initial correction value;

An axle speed limit correction value is calculated according to the wheel speed difference correction value, and the basic axle speed limit value is corrected according to the axle speed limit correction value to obtain the drive shaft axle speed limit value.

Optionally, the working state of the high-frequency control layer includes a preparation state, a control state and a release state;

The method includes:

When the wheel does not slip, the high-frequency control layer is in a ready state;

When the high-frequency control layer is in the ready state, if the vehicle enters the transient condition of wheel slippage, the torque limiting function of the high-frequency control layer is activated and jumps from the ready state to the control state;

After the high-frequency control layer enters the control state, the motor speed limit is calculated according to the drive shaft speed limit, the torque limit is calculated according to the motor speed limit, and the output of the vehicle drive motor is controlled according to the torque limit Torque; among them, if the TCS function of the ESP is activated, or the error between the intervention torque output by the ESP and the actual torque of the motor is within the preset error range, the high-frequency control layer will jump from the control state to the release state; if the preset time If the high-frequency control layer within the range does not jump from the control state to the release state, and returns to the non-slip state, the high-frequency control layer jumps from the control state to the ready state;

After the high-frequency control layer enters the release state, the torque limit function of the high-frequency control layer is turned off, and if it returns to the non-slip state, the high-frequency control layer jumps from the release state to the ready state.

Optionally, the working state of the low-frequency control layer includes an idle state, a control state, and a degraded control state;

The method includes:

When the wheel is not slipping, the low-frequency control layer is in an idle state;

When the ESP is degraded without failure, if the vehicle enters the steady state of wheel slippage, the TCS function in the ESP is activated, and the low-frequency control layer jumps from the idle state to the control state; after the low-frequency control layer enters the control state, the TCS in the ESP controls the The output torque of the vehicle drive motor; wherein, when the TCS function in the ESP is turned off, the low-frequency control layer jumps from the control state to the idle state;

When the ESP fault is degraded, if the high-frequency control layer is in the control state, and the high-frequency control layer has completed the shaft speed control under the transient condition where the shaft speed suddenly changes, the low-frequency control layer will jump from the idle state to the degraded control state; After the low-frequency control layer enters the degraded control state, the VCU or MCU controls the output torque of the vehicle drive motor according to the drive shaft speed limit; and, if it returns to the non-slip state, the low-frequency control layer jumps from the degraded control state to idle state.

Optionally, for a pure low-pass road surface, if the soaring of the shaft speed of the drive shaft has reached a peak point and begins to decrease, it is determined that the high-frequency control layer has completed the shaft speed control under the transient condition where the shaft speed suddenly changes;

For the separated road surface, if the difference between the axle speed of the drive axle and the reference vehicle speed is greater than the preset value, it is determined that the high-frequency control layer has completed axle speed control under the transient condition of sudden change in axle speed.

A second aspect of the present invention provides a driving anti-skid control system for a pure electric drive vehicle, comprising:

The target limit control layer is used to obtain the wheel speed of the vehicle and the steering wheel angle at the current moment, and determine the axle speed limit of the drive shaft according to the vehicle wheel speed and the steering wheel angle;

The high-frequency control layer is used to calculate the motor speed limit according to the drive shaft shaft speed limit, calculate the torque limit according to the motor speed limit, and calculate the torque limit according to the The torque limit controls the output torque of the vehicle drive motor;

The low-frequency control layer is used to control the output torque of the vehicle drive motor based on the TCS in the ESP when the wheel is in a steady state of slipping.

Optionally, the target restriction control layer includes:

The sensing information acquisition unit is used to acquire the vehicle wheel speed and steering wheel angle at the current moment;

a reference axle speed calculation unit, configured to calculate a reference vehicle speed according to the wheel speed of the vehicle, and calculate a reference axle speed according to the reference vehicle speed and the steering wheel angle;

a basic shaft speed limit calculation unit, configured to obtain a shaft speed offset value according to the reference shaft quick look-up table, and obtain a basic shaft speed limit value according to the reference shaft speed and the shaft speed offset value; and

Axle speed limit correction calculation unit, used for calculating the wheel speed difference between the left and right driving wheels of the vehicle and taking the absolute value to obtain the wheel speed difference, and revising the basic axle speed limit according to the wheel speed difference to obtain the Drive shaft shaft speed limit.

Optionally, the high-frequency control layer includes a high-frequency control state management unit, a motor speed limit calculation unit, and a motor speed limit unit; the high-frequency control state management unit is used to manage the working state of the high-frequency control layer. , the working state of the high-frequency control layer includes a preparation state, a control state and a release state;

in:

When the wheel does not slip, the high-frequency control state management unit controls the high-frequency control layer to enter a ready state;

When the high-frequency control layer is in the standby state, if the vehicle enters the transient condition of wheel slippage, the torque limiting function of the motor speed limiting unit is activated, and the high-frequency control state management unit controls the high-frequency control layer from the standby state. Jump to control state;

After the high-frequency control layer enters the control state, the motor speed limit calculation unit calculates the motor speed limit according to the drive shaft shaft speed limit; the motor speed limit unit calculates the torque limit according to the motor speed limit, and control the output torque of the vehicle drive motor according to the torque limit; wherein, if the TCS function of the ESP is activated, or the error between the intervention torque output by the ESP and the actual torque of the motor is within a preset error range, the high-frequency control The state management unit controls the high-frequency control layer to jump from the control state to the release state; if the high-frequency control layer does not jump from the control state to the release state within a preset time range, and returns to the non-slip state, the high-frequency control layer The control state management unit controls the high-frequency control layer to jump back from the control state to the preparation state;

After the high-frequency control layer enters the release state, the torque limiting function of the motor speed limiting unit is turned off, and if it returns to the non-slip state, the high-frequency control state management unit controls the high-frequency control layer to jump back from the control state. Ready state.

Optionally, the low-frequency control layer includes a low-frequency control state management unit and a shaft speed control unit; the low-frequency control state management unit is used to manage the working state of the low-frequency control layer, and the working state of the low-frequency control layer includes idle. state, control state, degraded control state; the shaft speed control unit includes TCS in ESP, and VCU or MCU;

in:

When the wheel does not slip, the low-frequency control state management unit controls the low-frequency control layer to enter an idle state;

When the ESP is degraded without failure, if the vehicle enters the steady state of wheel slippage, the TCS function in the ESP is activated, and the low-frequency control state management unit controls the low-frequency control layer to jump from the idle state to the control state; the low-frequency control layer enters the control state After the state, the TCS in the ESP controls the output torque of the vehicle drive motor; wherein, when the TCS function in the ESP is turned off, the low-frequency control state management unit controls the low-frequency control layer to jump from the control state to the idle state;

When the ESP fault is degraded, if the high-frequency control layer is in the control state, and the high-frequency control layer has completed the shaft speed control under the transient condition of the sudden change of the shaft speed, the low-frequency control state management unit controls the low-frequency control layer to be idle. The state jumps to the degraded control state; after the low frequency control layer enters the degraded control state, the VCU or MCU controls the output torque of the vehicle drive motor according to the shaft speed limit of the drive shaft; and, if it returns to the non-slip state, the low frequency The control state management unit controls the low frequency control layer to jump from the degraded control state to the idle state.

Implementing the above-mentioned method and system for driving anti-skid control of a pure electric drive vehicle has at least the following beneficial effects:

The change of wheel speed/axle speed in the process of wheel slip is decomposed into high-frequency and low-frequency changes, correspondingly, the anti-skid control requirements of vehicle driving are decomposed into high-frequency control requirements and low-frequency control requirements, and a high-frequency control layer is designed. The low-frequency control layer and the high-frequency control layer respectively meet the high-frequency control requirements and low-frequency control requirements, which can effectively suppress the rapid increase of the drive shaft shaft speed under the transient conditions of rapid changes in the drive shaft shaft speed, and can also be used in a relatively stable steady state of the drive shaft shaft speed. Accurate control of the shaft speed of the drive shaft under working conditions.

Other features and advantages of the present invention will be set forth in the description that follows.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

FIG. 1 is a flow chart of a method for controlling anti-skid driving of a pure electric drive vehicle according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a working state of a high-frequency control layer in an embodiment of the present invention.

FIG. 3 is a schematic diagram of a working state of a low frequency control layer in an embodiment of the present invention.

FIG. 4 is a schematic structural diagram of a frame structure of a driving anti-skid control system for a pure electric drive vehicle according to an embodiment of the present invention.

FIG. 5 is a schematic diagram of a frame structure of a target restriction control layer in an embodiment of the present invention.

FIG. 6 is a schematic diagram of a frame structure of a high frequency control layer in an embodiment of the present invention.

FIG. 7 is a schematic diagram of a frame structure of a low frequency control layer in an embodiment of the present invention.

Detailed ways

Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. In addition, in order to better illustrate the present invention, numerous specific details are given in the following specific embodiments. It will be understood by those skilled in the art that the present invention may be practiced without certain specific details. In some instances, means well known to those skilled in the art have not been described in detail in order not to obscure the subject matter of the present invention.

An embodiment of the present invention provides a driving anti-skid control method for a pure electric drive vehicle. The method in this embodiment is implemented based on a pure electric drive vehicle driving anti-skid control system. The control system includes a target limit control layer, a high-frequency control layer, and a low-frequency control layer. The control layer; the control system can be specifically implemented by hardware devices such as a vehicle vehicle controller (VCU) or a drive motor controller (MCU). Referring to FIG. 1 , the method in this embodiment includes the following steps S1 to S3:

Step S1, the target limit control layer obtains the vehicle wheel speed and the steering wheel angle at the current moment, and determines the drive shaft speed limit value according to the vehicle wheel speed and the steering wheel angle;

Specifically, the target limit control layer described in this embodiment is used to calculate the desired drive shaft speed limit value, as the control target of the high frequency control layer in step S2 and the low frequency control layer in step S3;

Step S2, when in the transient condition of wheel slippage, the high-frequency control layer calculates the motor speed limit according to the drive shaft speed limit, and calculates the torque limit according to the motor speed limit, and calculates the torque limit according to the motor speed limit. The torque limit controls the output torque of the vehicle drive motor;

Specifically, the high-frequency control layer described in this embodiment is used for the axle speed control under the transient condition where the axle speed of the drive shaft changes suddenly when the wheel slips. function, but calculate the motor torque limit according to the drive shaft speed limit, and send the motor torque limit to the motor torque execution unit to control the output torque of the vehicle drive motor. Compared with the traditional TCS function, the drive shaft The control of the sudden change of speed, the control link of the high-frequency control layer in the embodiment of the present invention is short, the response is fast, the rapid adjustment of the shaft speed can be realized, and the rapid increase of the shaft speed of the drive shaft can be effectively suppressed;

Step S3, when in the steady state of wheel slippage, the low-frequency control layer controls the output torque of the vehicle drive motor based on the TCS in the ESP;

Specifically, the low-frequency control layer in this embodiment is used to control the shaft speed of the drive shaft under the condition that the shaft speed of the drive shaft is relatively stable when the wheel slips, and the precise control of the shaft speed of the drive shaft is realized by calling the TCS function of the ESP.

It should be noted that the step S2 and the step S3 are performed in parallel and synchronously, so as to realize the driving anti-skid control of the pure electric drive vehicle under all working conditions.

The embodiment of the present invention decomposes the change of wheel speed/axle speed during the wheel slipping process into high-frequency change and low-frequency change, correspondingly decomposes the vehicle drive anti-skid control demand into high-frequency control demand and low-frequency control demand, and designs a The high-frequency control layer and the low-frequency control layer deal with the high-frequency control requirements and the low-frequency control requirements respectively, which can effectively suppress the rapid increase of the drive shaft shaft speed under the transient condition of the rapid change of the drive shaft shaft speed, and can also be used when the drive shaft shaft speed is relatively high. Accurate control of the shaft speed of the drive shaft under stable steady state conditions.

In a specific example, the step S1 of determining the drive shaft speed limit value according to the vehicle wheel speed and the steering wheel angle specifically includes:

Step S11, calculating a reference vehicle speed according to the vehicle wheel speed, and calculating a reference axle speed according to the reference vehicle speed and the steering wheel angle;

Specifically, there is a corresponding relationship between the axle speed and the vehicle speed and the steering wheel angle. The reference axle speed in this embodiment is the axle speed of the drive axle when the vehicle wheels are not slipping. The wheelbase, center of mass position, and steering transmission ratio are used to calculate the shaft speed of the drive shaft in a non-slip state, as the reference shaft speed;

Step S12, obtaining a shaft speed offset value according to the reference shaft quick look-up table, and obtaining a basic shaft speed limit value according to the reference shaft speed and shaft speed offset value;

Specifically, before the implementation of this embodiment, the corresponding relationship between different reference axle speeds and axle speed offset values can be obtained through real vehicle calibration data, and saved as table data. The table data can obtain the axle speed offset value corresponding to the reference axle speed; wherein, the reference axle speed and the axle speed offset value are added together and then multiplied by the road adhesion coefficient to obtain the basic axle speed limit value, The road surface adhesion coefficient is a known parameter, which is used to correct the added value of the reference axle speed and the axle speed offset value;

Step S13, calculating the wheel speed difference between the left and right driving wheels of the vehicle and taking the absolute value to obtain the wheel speed difference, and correcting the basic axle speed limit value according to the wheel speed difference to obtain the drive shaft axle speed limit value;

Specifically, the wheel speed difference between the left and right driving wheels of the vehicle can be obtained from the ESP through the CAN bus;

Wherein, modifying the basic shaft speed limit value according to the wheel speed difference to obtain the drive shaft shaft speed limit value includes:

Step S131, obtain the corresponding dead zone threshold according to the reference vehicle speed look-up table, determine whether the wheel speed difference is greater than the dead zone threshold, if it is greater than the dead zone threshold, perform wheel speed difference correction, if it is less than the dead zone threshold, do not perform wheel speed. difference correction;

Specifically, in this embodiment, the dead zone threshold is calculated according to the reference vehicle speed look-up table; the purpose of setting the dead zone is to filter out the wheel speed difference caused by normal wheel speed fluctuations; when the reference vehicle speed is low, ensure the correct wheel speed difference. For fast response, the dead zone threshold needs to be set smaller. When the reference speed is high, the real-time requirements for wheel braking control are reduced, and the dead zone threshold can be set larger;

Step S132: When the wheel speed difference is corrected, if the wheel speed difference increases, multiply the wheel speed difference by a preset correction coefficient to obtain an initial correction value of the wheel speed difference, and the preset correction coefficient takes a value of 0 to 1; If the difference decreases, the wheel speed difference is subjected to the drop delay processing to obtain the initial correction value of the wheel speed difference;

Specifically, in this embodiment, the wheel speed difference rising rate is adjusted, and its function is to adjust the rising rate of the wheel speed difference correction value when the actual wheel speed difference rises, so as to realize the rapid increase of the wheel speed on the low side of the separation road. In addition, in this embodiment, the wheel speed difference drop is also delayed. When the wheel speed difference decreases, the shaft speed limit of the drive shaft will also drop accordingly. There is a delay in the delivery of the limited execution unit, which will cause the limit to work, but it does not meet expectations. Therefore, the wheel speed difference is processed with a drop delay, that is, a queue is used to save the wheel speed difference historical data for a certain length of time, so as to A delayed output that realizes its value;

Step S133, obtaining a final wheel speed difference correction value according to the preset wheel speed difference limit value and the wheel speed difference initial correction value;

Specifically, in the embodiment of the present invention, the initial correction value of the wheel speed difference is limited according to the preset wheel speed difference limit value, so as to realize the limitation of the maximum value of the wheel speed on the low side of the separated road surface; the initial correction value of the wheel speed difference is limited. It means that the initial correction value of the wheel speed difference obtained by the correction in step S132 needs to meet the range of the preset wheel speed difference limit value. No correction is performed. If the initial correction value of the wheel speed difference does not meet the range of the preset wheel speed difference limit value, the correction is performed, and the preset wheel speed difference limit value is used as the final wheel speed difference correction value;

Step S134, calculating an axle speed limit correction value according to the wheel speed difference correction value, and correcting the basic axle speed limit according to the axle speed limit correction value to obtain the drive shaft axle speed limit;

Specifically, the requirement for correcting the basic axle speed limit based on the wheel speed difference correction value is to superimpose the axle speed increment corresponding to the wheel speed difference correction value as a correction value to the basic axle speed limit value;

It should be noted that the slipping speed of the wheels on the low-attached side of the separated road surface is faster and the peak value is higher, which brings about problems such as vehicle swaying, damage to the life span, etc.; therefore, in the step S13, the basic axle speed limit is subjected to the separation road axle speed limit. Limit value correction; among them, when the drive shaft drives on the separated road, the left and right wheels will have a wheel speed difference. Under this condition, the ESP must apply braking torque to the wheels on the low side, so that the wheels on the high side can obtain driving torque; The magnitude of the speed difference directly affects the magnitude of the wheel braking torque applied by the ESP. Therefore, the embodiment of the present invention corrects the axle speed limit based on the wheel speed difference to avoid causing the wheel braking torque applied by the ESP to be too small. The method can adjust the rising rate of the wheel speed difference and the upper limit of the wheel speed difference, and cooperate with the wheel braking control of ESP to improve the driving performance of the road on the flat road and the slope.

In a specific example, referring to FIG. 2 , the working states of the high-frequency control layer include a preparation state (4-1), a control state (4-2) and a release state (4-3);

Referring to Figure 2, the workflow of the high-frequency control layer specifically includes:

step11. When the wheel does not slip, the high-frequency control layer is in a ready state;

Specifically, in the standby state, the high-frequency control layer is always ready to limit the driving torque,

Suppress the speed of the drive shaft from rising;

step12. When the high-frequency control layer is in the preparatory state, if the vehicle enters the transient condition of wheel slippage, the torque limiting function of the high-frequency control layer is activated and jumps from the preparatory state to the control state (ie, 4 in Figure 2). -4 arrows indicate the jump state);

step13. After the high-frequency control layer enters the control state, the motor speed limit is calculated according to the drive shaft speed limit, the torque limit is calculated according to the motor speed limit, and the vehicle drive motor is controlled according to the torque limit. The output torque of the drive shaft can be quickly adjusted;

Among them, if the TCS function of the ESP is activated, or the error between the intervention torque output by the ESP and the actual torque of the motor (that is, the motor output torque at the current moment) is within the preset error range, it means that the high-frequency control requirement has been completed, and no need at this time. Then perform high-frequency control, but the torque limit should be activated by the TCS function, then the high-frequency control layer jumps from the control state to the release state (that is, the jump state shown by the arrows 4-5 in Figure 2);

If the high-frequency control layer does not jump from the control state to the release state within the preset time range (that is, the jump state indicated by the arrows 4-5 in Figure 2 does not occur), and returns to the non-slip state, the high-frequency control layer The layer jumps back from the control state to the ready state (that is, the jump state shown by the arrows 4-6 in Figure 2);

Specifically, after obtaining the drive shaft speed limit, the motor speed limit can be calculated according to the transmission ratio and the tire radius, and the specific formula is: motor speed limit = drive shaft speed limit × 1000m/60min/ (2pi×Rm)×transmission ratio; in this formula, the unit of motor speed limit is rpm, and the unit of drive shaft speed limit is km/h;

Wherein, the corresponding torque limit can be obtained by converting according to the motor speed limit, and the torque limit is used to limit the torque of the driving motor, so as to control the motor speed below the motor speed limit; exemplarily, the motor speed limit For example, PI closed-loop control can be used to limit the motor speed; when the motor speed limit enable state is enabled, and the actual speed of the motor reaches the motor speed limit, the PI closed-loop control is activated;

step14. After the high-frequency control layer enters the release state, the torque-limiting function of the high-frequency control layer is turned off, and the high-frequency control layer does not intervene in the driving torque at this time; The high-frequency control layer jumps back from the release state to the ready state (ie, the jumping state indicated by the arrows 4-7 in FIG. 2 ), and is ready for the next high-frequency control intervention.

In a specific example, referring to FIG. 3 , the working states of the low-frequency control layer include an idle state (5-1), a control state (5-2), and a degraded control state (5-3);

Referring to Figure 3, the workflow of the low-frequency control layer specifically includes:

step21. When the wheel does not slip, the low-frequency control layer is in an idle state;

Specifically, the idle state is a state in which the low frequency control is not activated;

step22. When the ESP is degraded without failure, if the vehicle enters the steady state of wheel slippage, the TCS function in the ESP is activated, and the low-frequency control layer jumps from the idle state to the control state (that is, arrows 5-4 in Figure 3). jump state); after the low-frequency control layer enters the control state, the TCS in the ESP controls the output torque of the vehicle drive motor; wherein, when the TCS function in the ESP is turned off, the low-frequency control layer jumps from the control state to the idle state (that is, Fig. The jump state shown by the 5-5 arrow in 3);

Specifically, when the ESP is degraded without failure, the TCS function of the ESP is available, and after the low-frequency control layer enters the control state, the TCS in the ESP controls the output torque of the vehicle drive motor;

step23. When the ESP fault is degraded, if the high-frequency control layer is in the control state, and the high-frequency control layer has completed the shaft speed control under the transient condition of the sudden change of the shaft speed, the low-frequency control layer will jump from the idle state to the degraded control. state (that is, the jump state indicated by the arrows 5-6 in Figure 3); after the low-frequency control layer enters the degraded control state, the VCU or MCU controls the output torque of the vehicle drive motor according to the drive shaft speed limit; and, if When the shaft speed of the drive shaft returns to the non-slip state, the low-frequency control layer jumps from the degraded control state to the idle state (that is, the jump state shown by the arrow 5-1 in Figure 3);

Among them, for the pure low-attached road, if the soaring speed of the drive shaft has reached the peak point and begins to decrease, it is determined that the high-frequency control layer has completed the shaft speed control under the transient condition of the sudden change of the shaft speed; for the separated road, if If the difference between the shaft speed of the drive shaft and the reference vehicle speed is greater than the preset value, it is determined that the high-frequency control layer has completed the shaft speed control under the transient condition where the shaft speed suddenly changes;

Specifically, if the ESP is degraded due to a fault and the TCS function of the ESP is unavailable, the low-frequency control layer still needs to control the soaring speed of the shaft to ensure driving safety as much as possible, and prevent battery overcurrent and poor wear and tear. Therefore, the low-frequency control layer After entering the degraded control state, the VCU or MCU controls the output torque of the vehicle drive motor according to the drive shaft speed limit, that is, calculates the corresponding output torque limit according to the drive shaft speed limit, and performs closed-loop control, so that The output torque of the vehicle drive motor is less than the output torque limit.

It can be seen from the description of the above embodiments that the embodiments of the present invention have the following advantages:

(1) The embodiment of the present invention can improve the safety and smoothness of the vehicle under the starting and acceleration conditions of the low-attached road, and improve the quality of the product;

(2) The embodiment of the present invention can effectively protect the differential and power battery of the vehicle, reduce the failure rate and prolong its service life;

(3) The embodiment of the present invention can reduce the development difficulty of vehicle drivability and low-slip control performance; the present invention can decouple vehicle drivability calibration and low-slip control calibration, so that the acceleration slope of the vehicle's accelerator torque and the maximum torque decline rate are not Then affect the performance of low-attachment control. Because the embodiment of the present invention uses the high-frequency control layer to deal with the working condition of sudden and rapid change of the axle speed, there is no longer too many requirements for the acceleration slope of the accelerator torque and the maximum torque decrease rate.

Referring to FIG. 4 , corresponding to the method in the above-mentioned embodiment, another embodiment of the present invention provides a driving anti-skid control system for a pure electric drive vehicle, which can be used to implement the steps of the method in the above-mentioned embodiment. The system in this embodiment includes:

The target limit control layer 1 is used to obtain the wheel speed of the vehicle and the steering wheel angle at the current moment, and determine the axle speed limit of the drive shaft according to the vehicle wheel speed and the steering wheel angle;

The high-frequency control layer 2 is used for calculating the motor speed limit according to the drive shaft shaft speed limit, and calculating the torque limit according to the motor speed limit, and according to the The above torque limit controls the output torque of the vehicle drive motor;

The low-frequency control layer 3 is used to control the output torque of the vehicle drive motor based on the TCS in the ESP when the wheel is in a steady state of slipping.

Optionally, referring to FIG. 5 , the target restriction control layer 1 includes:

The sensing information acquisition unit 11 is used to acquire the wheel speed and steering wheel angle of the vehicle at the current moment;

a reference axle speed calculation unit 12, configured to calculate a reference vehicle speed according to the vehicle wheel speed, and calculate a reference axle speed according to the reference vehicle speed and the steering wheel angle;

a basic shaft speed limit calculation unit 13, configured to obtain a shaft speed offset value according to the reference shaft quick look-up table, and obtain a basic shaft speed limit value according to the reference shaft speed and the shaft speed offset value; and

The axle speed limit correction calculation unit 14 is used to calculate the wheel speed difference between the left and right driving wheels of the vehicle and take the absolute value to obtain the wheel speed difference, and correct the basic axle speed limit according to the wheel speed difference to obtain the obtained wheel speed difference. the shaft speed limit for the drive shaft.

Wherein, the basic shaft speed limit calculation unit 13 is specifically used for:

Obtain the corresponding dead zone threshold according to the reference vehicle speed look-up table, determine whether the wheel speed difference is greater than the dead zone threshold, if it is greater than the dead zone threshold, perform wheel speed difference correction, if it is less than the dead zone threshold, do not correct the wheel speed difference;

When the wheel speed difference is corrected, if the wheel speed difference increases, the wheel speed difference is multiplied by a preset correction coefficient to obtain the initial correction value of the wheel speed difference, and the preset correction coefficient takes a value of 0 to 1; if the wheel speed difference decreases, Then, the drop delay processing is performed on the wheel speed difference to obtain the initial correction value of the wheel speed difference;

obtaining a final wheel speed difference correction value according to the preset wheel speed difference limit value and the wheel speed difference initial correction value; and

An axle speed limit correction value is calculated according to the wheel speed difference correction value, and the basic axle speed limit value is corrected according to the axle speed limit correction value to obtain the drive shaft axle speed limit value.

Optionally, referring to FIG. 6 , the high-frequency control layer 2 includes a high-frequency control state management unit 21, a motor speed limit calculation unit 22, and a motor speed limit unit 23; the high-frequency control state management unit 21 is used to manage The working state of the high-frequency control layer 2, the working state of the high-frequency control layer includes a preparation state, a control state and a release state;

in:

When the wheel does not slip, the high-frequency control state management unit 21 controls the high-frequency control layer 2 to enter a ready state;

When the high-frequency control layer 2 is in the ready state, if the vehicle enters the transient condition of wheel slippage, the torque limiting function of the motor speed limiting unit 23 is activated, and the high-frequency control state management unit 21 controls the high-frequency control layer. 2 Jump from the ready state to the control state;

After the high-frequency control layer 2 enters the control state, the motor speed limit calculation unit 22 calculates the motor speed limit according to the drive shaft shaft speed limit; the motor speed limit unit 23 calculates the torque according to the motor speed limit limit, and control the output torque of the vehicle drive motor according to the torque limit; wherein, if the TCS function of the ESP is activated, or the error between the intervention torque output by the ESP and the actual torque of the motor is within the preset error range, the The high-frequency control state management unit 21 controls the high-frequency control layer 2 to jump from the control state to the release state; if the high-frequency control layer 2 does not jump from the control state to the release state within the preset time range, and returns to the non-slip state , then the high-frequency control state management unit 21 controls the high-frequency control layer 2 to jump back from the control state to the preparatory state;

After the high-frequency control layer 2 enters the release state, the torque limiting function of the motor speed limiting unit 23 is turned off, and if it returns to the non-slip state, the high-frequency control state management unit 21 controls the high-frequency control layer 2 from the control The state jumps back to the ready state.

Optionally, referring to FIG. 7 , the low frequency control layer 3 includes a low frequency control state management unit 31 and a shaft speed control unit 32; the low frequency control state management unit 31 is used to manage the working state of the low frequency control layer 3, so The working states of the low-frequency control layer 3 include idle state, control state, and degraded control state; the shaft speed control unit includes TCS in ESP, and VCU or MCU;

in:

When the wheel does not slip, the low-frequency control state management unit 31 controls the low-frequency control layer 3 to enter the idle state;

When the ESP is degraded without failure, if the vehicle enters the steady state of wheel slippage, the TCS function in the ESP is activated, and the low-frequency control state management unit 31 controls the low-frequency control layer 3 to jump from the idle state to the control state; the low-frequency control layer 3 After entering the control state, the TCS in the ESP controls the output torque of the vehicle drive motor; wherein, when the TCS function in the ESP is turned off, the low-frequency control state management unit 31 controls the low-frequency control layer 3 to jump from the control state to the idle state ;

When the ESP fault is degraded, if the high-frequency control layer is in the control state, and the high-frequency control layer has completed the shaft speed control under the transient condition of the sudden change of the shaft speed, the low-frequency control state management unit 31 controls the low-frequency control layer 3 Jump from the idle state to the degraded control state; after the low-frequency control layer 3 enters the degraded control state, the VCU or MCU controls the output torque of the vehicle drive motor according to the shaft speed limit of the drive shaft; and, if it returns to the non-slip state, then The low frequency control state management unit 31 controls the low frequency control layer 3 to jump from the degraded control state to the idle state.

Among them, for the pure low-attached road, if the soaring speed of the drive shaft has reached the peak point and begins to decrease, it is determined that the high-frequency control layer has completed the shaft speed control under the transient condition of the sudden change of the shaft speed; for the separated road, if If the difference between the shaft speed of the drive shaft and the reference vehicle speed is greater than the preset value, it is determined that the high-frequency control layer has completed the shaft speed control in the transient condition of the sudden change of the shaft speed.

The system embodiments described above are only illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in One place, or it can be distributed over multiple network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution in this embodiment.

It should be noted that the system described in the foregoing embodiment corresponds to the method described in the foregoing embodiment. Therefore, the part of the system described in the foregoing embodiment that is not described in detail can be obtained by referring to the content of the method described in the foregoing embodiment, that is, the description of the method described in the foregoing embodiment. The content of the specific steps can be understood as the functions that can be implemented by the system in this embodiment, and details are not repeated here.

Furthermore, if the pure electric vehicle driving anti-skid control system described in the above embodiments is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium.

Various embodiments of the present invention have been described above, and the foregoing descriptions are exemplary, not exhaustive, and not limiting of the disclosed embodiments. Numerous modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

Claims (10)

1. A pure electric drive vehicle driving anti-skid control method is characterized in that, comprising: The target limit control layer obtains the vehicle wheel speed and the steering wheel angle at the current moment, and determines the drive shaft speed limit according to the vehicle wheel speed and the steering wheel angle; When in the transient condition of wheel slip, the high-frequency control layer calculates the motor speed limit according to the drive shaft shaft speed limit, calculates the torque limit according to the motor speed limit, and calculates the torque limit according to the torque limit Control the output torque of the vehicle drive motor; When in the steady state of wheel slippage, the low-frequency control layer controls the output torque of the vehicle drive motor based on the TCS in the ESP. 2 . The anti-skid control method for driving a pure electric drive vehicle according to claim 1 , wherein the determining the limit value of the shaft speed of the drive shaft according to the wheel speed of the vehicle and the steering wheel angle specifically includes: 3 . Calculate a reference vehicle speed according to the vehicle wheel speed, and calculate a reference axle speed according to the reference vehicle speed and the steering wheel angle; Obtain the shaft speed offset value according to the reference shaft quick look-up table, and obtain the basic shaft speed limit value according to the reference shaft speed and shaft speed offset value; Calculate the wheel speed difference between the left and right driving wheels of the vehicle and take the absolute value to obtain the wheel speed difference, and modify the basic axle speed limit according to the wheel speed difference to obtain the drive axle axle speed limit. 3 . The anti-skid control method for driving a pure electric drive vehicle according to claim 2 , wherein, the basic axle speed limit value is obtained by modifying the basic axle speed limit value according to the wheel speed difference, include: Obtain the corresponding dead zone threshold according to the reference vehicle speed look-up table, determine whether the wheel speed difference is greater than the dead zone threshold, if it is greater than the dead zone threshold, perform wheel speed difference correction, if it is less than the dead zone threshold, do not correct the wheel speed difference; When the wheel speed difference is corrected, if the wheel speed difference increases, the wheel speed difference is multiplied by a preset correction coefficient to obtain the initial correction value of the wheel speed difference, and the preset correction coefficient takes a value of 0 to 1; if the wheel speed difference decreases, Then, the drop delay processing is performed on the wheel speed difference to obtain the initial correction value of the wheel speed difference; Obtain the final wheel speed difference correction value according to the preset wheel speed difference limit value and the wheel speed difference initial correction value; An axle speed limit correction value is calculated according to the wheel speed difference correction value, and the basic axle speed limit value is corrected according to the axle speed limit correction value to obtain the drive shaft axle speed limit value. The anti-skid control method for driving a pure electric vehicle according to claim 1, wherein the working state of the high-frequency control layer includes a preparation state, a control state and a release state; The method includes: When the wheel does not slip, the high-frequency control layer is in a ready state; When the high-frequency control layer is in the ready state, if the vehicle enters the transient condition of wheel slippage, the torque limiting function of the high-frequency control layer is activated and jumps from the ready state to the control state; After the high-frequency control layer enters the control state, the motor speed limit is calculated according to the drive shaft speed limit, the torque limit is calculated according to the motor speed limit, and the output of the vehicle drive motor is controlled according to the torque limit Torque; among them, if the TCS function of the ESP is activated, or the error between the intervention torque output by the ESP and the actual torque of the motor is within the preset error range, the high-frequency control layer will jump from the control state to the release state; if the preset time If the high-frequency control layer within the range does not jump from the control state to the release state, and returns to the non-slip state, the high-frequency control layer jumps from the control state to the ready state; After the high-frequency control layer enters the release state, the torque limit function of the high-frequency control layer is turned off, and if it returns to the non-slip state, the high-frequency control layer jumps from the release state to the ready state. 5 . The anti-skid control method for driving a pure electric drive vehicle according to claim 4 , wherein the working state of the low-frequency control layer includes an idle state, a control state, and a degraded control state; 6 . The method includes: When the wheel is not slipping, the low-frequency control layer is in an idle state; When the ESP is degraded without failure, if the vehicle enters the steady state of wheel slippage, the TCS function in the ESP is activated, and the low-frequency control layer jumps from the idle state to the control state; after the low-frequency control layer enters the control state, the TCS in the ESP controls the The output torque of the vehicle drive motor; wherein, when the TCS function in the ESP is turned off, the low-frequency control layer jumps from the control state to the idle state; When the ESP fault is degraded, if the high-frequency control layer is in the control state, and the high-frequency control layer has completed the shaft speed control under the transient condition where the shaft speed suddenly changes, the low-frequency control layer will jump from the idle state to the degraded control state; After the low-frequency control layer enters the degraded control state, the VCU or MCU controls the output torque of the vehicle drive motor according to the drive shaft speed limit; and, if it returns to the non-slip state, the low-frequency control layer jumps from the degraded control state to idle state. 6 . The anti-skid control method for driving a pure electric vehicle according to claim 5 , wherein, for a pure low-pass road surface, if the soaring of the shaft speed of the drive shaft has reached a peak point and begins to decrease, it is determined that the high-frequency control layer has Complete shaft speed control under transient conditions with sudden changes in shaft speed; For the separated road surface, if the difference between the axle speed of the drive axle and the reference vehicle speed is greater than the preset value, it is determined that the high-frequency control layer has completed axle speed control under the transient condition of sudden change in axle speed. 7. A driving anti-skid control system for a pure electric drive vehicle, characterized in that, comprising: The target limit control layer is used to obtain the wheel speed of the vehicle and the steering wheel angle at the current moment, and determine the axle speed limit of the drive shaft according to the vehicle wheel speed and the steering wheel angle; The high-frequency control layer is used to calculate the motor speed limit according to the drive shaft shaft speed limit, calculate the torque limit according to the motor speed limit, and calculate the torque limit according to the The torque limit controls the output torque of the vehicle drive motor; The low-frequency control layer is used to control the output torque of the vehicle drive motor based on the TCS in the ESP when the wheel is in a steady state of slipping. 8 . The anti-skid control system for driving a pure electric drive vehicle according to claim 7 , wherein the target limit control layer comprises: The sensing information acquisition unit is used to acquire the vehicle wheel speed and steering wheel angle at the current moment; a reference axle speed calculation unit, configured to calculate a reference vehicle speed according to the wheel speed of the vehicle, and calculate a reference axle speed according to the reference vehicle speed and the steering wheel angle; a basic shaft speed limit calculation unit, configured to obtain a shaft speed offset value according to the reference shaft quick look-up table, and obtain a basic shaft speed limit value according to the reference shaft speed and the shaft speed offset value; and Axle speed limit correction calculation unit, used for calculating the wheel speed difference between the left and right driving wheels of the vehicle and taking the absolute value to obtain the wheel speed difference, and revising the basic axle speed limit according to the wheel speed difference to obtain the Drive shaft shaft speed limit. 9 . The anti-skid control system for driving a pure electric drive vehicle according to claim 8 , wherein the high-frequency control layer comprises a high-frequency control state management unit, a motor speed limit calculation unit, and a motor speed limit unit; the The high-frequency control state management unit is used to manage the working state of the high-frequency control layer, and the working state of the high-frequency control layer includes a preparation state, a control state and a release state; in: When the wheel does not slip, the high-frequency control state management unit controls the high-frequency control layer to enter a ready state; When the high-frequency control layer is in the standby state, if the vehicle enters the transient condition of wheel slippage, the torque limiting function of the motor speed limiting unit is activated, and the high-frequency control state management unit controls the high-frequency control layer from the standby state. Jump to control state; After the high-frequency control layer enters the control state, the motor speed limit calculation unit calculates the motor speed limit according to the drive shaft shaft speed limit; the motor speed limit unit calculates the torque limit according to the motor speed limit, and control the output torque of the vehicle drive motor according to the torque limit; wherein, if the TCS function of the ESP is activated, or the error between the intervention torque output by the ESP and the actual torque of the motor is within a preset error range, the high-frequency control The state management unit controls the high-frequency control layer to jump from the control state to the release state; if the high-frequency control layer does not jump from the control state to the release state within a preset time range, and returns to the non-slip state, the high-frequency control layer The control state management unit controls the high-frequency control layer to jump back from the control state to the preparation state; After the high-frequency control layer enters the release state, the torque limiting function of the motor speed limiting unit is turned off, and if it returns to the non-slip state, the high-frequency control state management unit controls the high-frequency control layer to jump back from the control state. ready state. 10 . The anti-skid control system for driving a pure electric vehicle according to claim 9 , wherein the low-frequency control layer comprises a low-frequency control state management unit and an axle speed control unit; the low-frequency control state management unit is used to manage all the 10 . The working state of the low-frequency control layer, the working state of the low-frequency control layer includes an idle state, a control state, and a degraded control state; the shaft speed control unit includes the TCS in the ESP, and the VCU or MCU; in: When the wheel does not slip, the low-frequency control state management unit controls the low-frequency control layer to enter an idle state; When the ESP is degraded without failure, if the vehicle enters the steady state of wheel slippage, the TCS function in the ESP is activated, and the low-frequency control state management unit controls the low-frequency control layer to jump from the idle state to the control state; the low-frequency control layer enters the control state After the state, the TCS in the ESP controls the output torque of the vehicle drive motor; wherein, when the TCS function in the ESP is turned off, the low-frequency control state management unit controls the low-frequency control layer to jump from the control state to the idle state; When the ESP fault is degraded, if the high-frequency control layer is in the control state, and the high-frequency control layer has completed the shaft speed control under the transient condition of the sudden change of the shaft speed, the low-frequency control state management unit controls the low-frequency control layer to be idle. The state jumps to the degraded control state; after the low frequency control layer enters the degraded control state, the VCU or MCU controls the output torque of the vehicle drive motor according to the shaft speed limit of the drive shaft; and, if it returns to the non-slip state, the low frequency The control state management unit controls the low frequency control layer to jump from the degraded control state to the idle state.

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