An electric vehicle drive slip control method and system

Abstract

The present application relates to the technical field of vehicle control, in particular to a kind of electric automobile drive anti-skid control method and system.If TCS is in the activated state, then output torque F t =F a , otherwise, the validity of brake pedal signal is judged;If valid, then output torque F t =F a , if invalid, then the slip rate λ is judged;If the slip rate λ is in the optimal slip rate interval, then drive anti-skid exit time T1 cumulative count is executed, drive anti-skid enable time T2 cumulative count is zero, until T1 is greater than drive anti-skid exit time T qu , then output torque F t =F a ;Otherwise, then drive anti-skid exit time T1 cumulative count is zero, drive anti-skid enable time T2 cumulative count is executed, until T2 is greater than drive anti-skid enable time T en , then judge whether current demand torque F a is greater than output torque limit F Limit ;If yes, then output torque F t =F a *C;If not, then output torque F t =F a .The present application saves the space in the car, simplifies the difficulty of hardware architecture design, and is conducive to the arrangement of hardware equipment.

Description

Technical Field

[0001] This invention relates to the field of vehicle control technology, and specifically to a method and system for anti-skid control of electric vehicle drive. Background Technology

[0002] With the increasing prominence of energy and environmental issues, electric vehicles have become a crucial topic in the development of the global automotive industry. my country has already achieved considerable success with electric vehicles. Compared to traditional vehicles, besides advantages such as zero emissions, low noise, and less pollution, the most significant differences lie in their energy utilization methods and electronic control technologies. Due to these substantial differences in energy utilization and their main structures, even some technologies currently mature in traditional vehicles, such as traction control, still require redevelopment for electric vehicles. Traction control systems are an active safety system in automobiles that ensures the vehicle can fully utilize ground adhesion, preventing skidding and thus improving acceleration performance. They can also enhance vehicle safety and traction to a certain extent, enabling safe and efficient driving.

[0003] Traction Control (TCS) is an important active safety control system in modern automobiles. It primarily prevents vehicle slippage on surfaces with low coefficients of friction by adjusting the driving force on the drive wheels during start-up or acceleration, thus maintaining directional stability and ensuring vehicle handling and driving safety. Existing TCS systems require independent control units and multiple related sensors installed throughout the vehicle, occupying more interior space and increasing the complexity of hardware architecture design. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing an electric vehicle drive anti-slip control method and system that does not require changes to the existing hardware architecture, saves interior space, simplifies design, and facilitates the layout of hardware equipment.

[0005] This invention provides a method for controlling anti-skid driving in electric vehicles, comprising the following steps:

[0006] Obtain the TCS operating status. If the TCS is active, output torque F. t =F a If the TCS is not activated, the validity of the brake pedal signal will be further determined.

[0007] If the brake pedal signal is valid, the output torque F t =F a If the brake pedal signal is invalid, the slip ratio λ is further determined.

[0008] If the slip ratio λ is within the optimal slip ratio range, then the anti-slip exit time T1 is incremented, and the anti-slip enable time T2 is incremented until T1 is greater than the anti-slip exit time T. qu Then the output torque F t =F a ;

[0009] If the slip ratio λ is not within the optimal slip ratio range, then the count of the drive anti-slip exit time T1 is reset to zero, and the count of the drive anti-slip enable time T2 is incremented until T2 is greater than the drive anti-slip enable time T. en Then, further determine the current required torque F. a Is it greater than the output torque limit F? Limit ;

[0010] If so, then the output torque F t =F a *C;

[0011] If not, then the output torque F t =F a .

[0012] Preferably, the validity determination of the brake pedal signal includes:

[0013] Obtain brake pedal opening information;

[0014] If the brake pedal opening is greater than the preset opening, the brake pedal signal is considered valid.

[0015] If the brake pedal opening is less than or equal to the preset opening, the brake pedal signal is deemed invalid.

[0016] Preferably, the slip ratio λ is calculated based on the motor speed W and the minimum tire angular velocity Wr, and the slip ratio λ is calculated separately for two working conditions: driving state and braking state.

[0017] Preferably, the calculation of the slip ratio λ includes:

[0018] In the driving state, slip ratio

[0019] Under the braking state, the slip ratio

[0020] Where R is the tire radius and i is the speed ratio of the reducer.

[0021] Preferably, the optimal slip ratio range is 0.05 to 0.2.

[0022] More preferably, the output torque limit F Limit According to the normal reaction force F of the groundz The value of F is obtained by taking the adhesion coefficient φ. Limit <F z *φ.

[0023] More preferably, the ground normal reaction force F z Including the front axle ground normal reaction force F zf and the ground normal reaction force F of the front and rear axles zr ;

[0024]

[0025]

[0026] Where m is the vehicle mass, g is the acceleration due to gravity, L is the vehicle wheelbase, a and b are the distances from the center of mass to the front and rear axles respectively, hg is the height of the center of mass, A is the vehicle's frontal area, p is the air density, and C... Lf C Lr These represent the front and rear lift coefficients, α is the road slope angle, and V is the vehicle speed.

[0027] This invention provides an electric vehicle drive anti-slip control system, which is integrated into the motor controller. The system is used to collect data such as brake pedal opening, tire angular velocity, vehicle driving mode, TCS operating status, and current required torque F. a The motor speed information is used to determine the output torque F. t =F a *C or F t =F a .

[0028] Preferably, the brake pedal opening, tire angular velocity, vehicle driving mode, TCS operating status, and current required torque F are... a All data are obtained through the vehicle's CAN network.

[0029] The beneficial effects of this invention are as follows:

[0030] 1. The anti-slip function is integrated into the motor controller, eliminating the need for additional control units. It only requires monitoring the wheel angular velocity; a small amount of data readily available for electric vehicles is sufficient to implement the anti-slip function. This eliminates the need to modify the existing hardware architecture, saving interior space, simplifying the design process, and facilitating hardware placement.

[0031] 2. This method is based on brake pedal opening, tire angular velocity, vehicle driving mode, TCS operating status, and current required torque F. aBy analyzing motor speed information, the system can identify road conditions and output the corresponding adhesion coefficient when slippage occurs, calculating the output torque limit. The entire control system has a relatively simple structure and high control accuracy and system response sensitivity. When slippage is detected, it can respond quickly within milliseconds, identify various road conditions, limit torque output from the power source, and quickly and efficiently suppress drive wheel slippage, improving the vehicle's adaptability to various road surfaces and enabling safe and efficient vehicle operation. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the method flow of the present invention;

[0033] Figure 2 This is a schematic diagram showing the relationship between the adhesion coefficient and the slip ratio in this invention;

[0034] Figure 3 This is a schematic diagram of the system control of the present invention. Detailed Implementation

[0035] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0036] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0037] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0038] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0039] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0040] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0041] References to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized. "A plurality" means "two or more."

[0042] Example 1

[0043] Figure 1 A preferred embodiment of this application is shown. Figure 1 The diagram shows a flowchart of an electric vehicle drive anti-slip control method according to the first embodiment of this application. For ease of explanation, only the parts related to this embodiment are shown, and the details are as follows:

[0044] This invention provides a method for controlling anti-skid driving in electric vehicles, comprising the following steps:

[0045] Step 1: Obtain the TCS operating status from the vehicle's CAN communication network. If the TCS is active, the controller executes the required torque F for the vehicle. a If the TCS is not active, then proceed to step 2.

[0046] Step 2: Obtain brake pedal opening information from the vehicle's CAN communication network. If the brake pedal opening is greater than 10%, the controller executes the required torque F for the entire vehicle. a If the output is executed, proceed to step 10; otherwise, proceed to step 3.

[0047] Step 3: Obtain the motor speed W from the motor speed sensor and the minimum tire angular velocity W from the wheel speed sensor. r Calculate the slip ratio λ:

[0048] When the vehicle is in driving mode

[0049] When the vehicle is braking

[0050] in R is the tire radius, and i is the speed ratio of the reducer;

[0051] like Figure 2 As shown, the longitudinal slip ratio λ of the wheel is controlled to be slightly less than the peak adhesion coefficient φ. xmax The corresponding slip ratio λ p Nearby, the shaded area in the figure is the most ideal, that is, the value of λ is controlled between 0.05 and 0.2. Proceed to step 4.

[0052] Step 4: Determine whether λ is within the optimal range of 0.05 to 0.2. If 0.05 < λ < 0.2, proceed to step 5. If λ < 0.05 or λ > 0.2, proceed to step 6.

[0053] Step 5: Execute the countdown for the drive anti-slip exit time T1, and reset the countdown for the drive anti-slip enable time T2 to zero. If T1 is greater than the drive anti-slip exit time T... qu Then the output drive anti-slip enable F = 0, torque derating factor C, C = 1; execute step 10, if T1 is less than the drive anti-slip exit time T qu If so, return to step 4;

[0054] Step 6: Execute the anti-slip exit time T1 increment count to zero, and increment the anti-slip enable time T2. If T2 is greater than the anti-slip enable time T... en If the output drive anti-slip enable F = 1 and the torque derating factor C < 1, then execute step 7. If T2 is less than the drive anti-slip enable time T... en If so, return to step 4;

[0055] Step 7: Obtain the current vehicle driving mode from the vehicle's CAN communication network and obtain the corresponding adhesion coefficient φ. The adhesion coefficient φ is obtained by testing under different driving modes.

[0056] Step 8, calculate the maximum torque output limit F. Limit ;

[0057] Calculate the vertical forces on the front and rear axles of the car:

[0058]

[0059]

[0060] Among them, F zf F zr These are the ground normal reaction forces at the front and rear axles, respectively; m is the vehicle mass; g is the acceleration due to gravity; L is the vehicle wheelbase; a and b are the distances from the center of mass to the front and rear axles, respectively; hg is the height of the center of mass; A is the vehicle's frontal area; p is the air density; and C... Lf C Lr These are the front and rear lift coefficients, respectively. All of the above parameters were obtained through experiments and measurements. 'a' is the road slope angle, which is input from the slope estimation module. 'V' is the vehicle speed.

[0061] The tangential reaction force generated by the torque acting on the drive wheels must not exceed the adhesion force; otherwise, slippage will occur, i.e., F Limit Condition F should be met. Limit <F z *φ, Output torque limit F Limit According to the normal reaction force F of the ground z Once the adhesion coefficient φ is obtained, proceed to step 9;

[0062] Step 9, determine the current torque requirement F of the vehicle. a Is it greater than the torque output limit F? Limit If F a >F Limit Then proceed to step 11. If F a ≤F Limit Then proceed to step 10;

[0063] Step 10, output torque F t =F a ;

[0064] Step 11, output torque F t =F a *C.

[0065] Example 2

[0066] like Figure 3 As shown, this embodiment provides an electric vehicle drive anti-slip control system. The system is integrated into the motor controller and is used to collect data such as brake pedal opening, tire angular velocity, vehicle driving mode, TCS operating status, and current required torque F. a The motor speed information is used to determine the output torque F. t =F a *C or F t =F a This includes brake pedal opening, tire angular velocity, vehicle driving mode, TCS operating status, and current torque demand F. aAll data is obtained through the vehicle's CAN network. Motor speed information is obtained from the motor position signal via a rotary transformer and calculated using the speed calculation module. The output torque F of this system... t The output is sent to the motor after consulting the table and calculating FOC.

[0067] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0068] In the above detailed description, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features of the single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, wherein each claim stands alone as a preferred embodiment of the invention.

[0069] The disclosed embodiments have been described above to enable any person skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0070] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as it is used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

[0071] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for controlling anti-skid driving in an electric vehicle, characterized in that, Includes the following steps: Obtain the TCS operating status. If the TCS is active, output torque F. t =F a If the TCS is not activated, the validity of the brake pedal signal will be further determined. If the brake pedal signal is valid, the output torque F t =F a If the brake pedal signal is invalid, the slip ratio λ is further determined. If the slip ratio λ is within the optimal slip ratio range, then the anti-slip exit time T1 is incremented, and the anti-slip enable time T2 is incremented until T1 is greater than the anti-slip exit time T. qu Then the output torque F t =F a ; If the slip ratio λ is not within the optimal slip ratio range, then the count of the drive anti-slip exit time T1 is reset to zero, and the count of the drive anti-slip enable time T2 is incremented until T2 is greater than the drive anti-slip enable time T. en Then, further determine the current required torque F. a Is it greater than the output torque limit F? Limit ; If so, then the output torque F t =F a *C; If not, then the output torque F t =F a .

2. The electric vehicle drive anti-skid control method according to claim 1, characterized in that, The validity determination of the brake pedal signal includes: Obtain brake pedal opening information; If the brake pedal opening is greater than the preset opening, the brake pedal signal is considered valid. If the brake pedal opening is less than or equal to the preset opening, the brake pedal signal is deemed invalid.

3. The electric vehicle drive anti-skid control method according to claim 1, characterized in that, The slip ratio λ is calculated based on the motor speed W and the minimum tire angular velocity Wr. The slip ratio λ is calculated separately for two working conditions: driving state and braking state.

4. The electric vehicle drive anti-skid control method according to claim 3, characterized in that, The calculation of the slip ratio λ includes: In the driving state, slip ratio Under the braking state, the slip ratio Where R is the tire radius and i is the speed ratio of the reducer.

5. The electric vehicle drive anti-skid control method according to claim 1, characterized in that: The optimal slip ratio range is 0.05 to 0.

2.

6. The electric vehicle drive anti-skid control method according to claim 1, characterized in that: The output torque limit F Limit According to the normal reaction force F of the ground z The value of F is obtained by taking the adhesion coefficient φ. Limit <F z *φ.

7. The electric vehicle drive anti-skid control method according to claim 6, characterized in that: The ground normal reaction force F z Including the front axle ground normal reaction force F zf and the ground normal reaction force F of the front and rear axles zr ; Where m is the vehicle mass, g is the acceleration due to gravity, L is the vehicle wheelbase, a and b are the distances from the center of mass to the front and rear axles respectively, hg is the height of the center of mass, A is the vehicle's frontal area, p is the air density, and C... Lf C Lr These represent the front and rear lift coefficients, α is the road slope angle, and V is the vehicle speed.

8. An electric vehicle drive anti-skid control system, characterized in that: The system is integrated into the motor controller and is used to collect data such as brake pedal opening, tire angular velocity, vehicle driving mode, TCS operating status, and current torque demand F. a The motor speed information is used to determine the output torque F. t =F a *C or F t =F a .

9. The electric vehicle drive anti-skid control system as described in claim 8, characterized in that: The brake pedal opening, tire angular velocity, vehicle driving mode, TCS operating status, and current torque demand F are mentioned. a All data are obtained through the vehicle's CAN network.

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