Pure electric vehicle crawling anti-slip combined control method applied to vehicle control unit

Abstract

The invention relates to a pure electric vehicle crawling anti-slope-sliding combined control method applied to a vehicle control unit. The method comprises the following steps that S1, whether the rotating speed n of a driving motor allows a vehicle to creep or prevent slope sliding or not is judged; s2, judging whether the vehicle creeping or slope slipping prevention is pre-enabled or not; s3, judging whether the vehicle is enabled to creep or anti-slip; s4, solving values of a and b in the discrete PI algorithm; s5, adjusting PI output of the VCU by using a discrete PI algorithm; s6, multiplying the discrete PI output by an output torque result of the driving motor characteristic curve to obtain a preliminary output torque T; and S7, the initial output torque is further limited, and finally, the limited final output torque Tresult is sent to a driving motor and a gearbox in the form of CAN message information. According to the pure electric vehicle crawling anti-slope-sliding combined control method applied to the vehicle control unit, the flexibility of the pure electric vehicle crawling and anti-slope-sliding control method is optimized, and the stability of the control method is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of control methods, and in particular to a combined control method for creeping and anti-slope sliding of a pure electric vehicle applied to a whole vehicle controller. Background Art

[0002] An important part of the commonly used control method in the automotive field is the discrete proportional integral differential algorithm (discrete PID), which is simple in principle and easy to implement:

[0003]

[0004] Where: T and k represent the sampling period and sampling number of VCU respectively; e(k) represents the difference between the expected quantity (such as expected vehicle speed) and the vehicle output quantity (such as actual vehicle speed) in the kth period; u(k) represents the output of the algorithm in the kth period, which is also the input of the actuator (such as the drive motor); k p , k i , k d They represent the parameters of the proportional, integral and differential links in the PID algorithm respectively; a and b represent the upper and lower limits of the VCU output respectively.

[0005] In the above discrete PID: k p , k i , k d a and b are all fixed values, which are not flexible enough; the differential link is prone to high-frequency interference, and the integral link is prone to large overshoot when e(k) is large, which is not conducive to vehicle stability control. Summary of the invention

[0006] The technical problem to be solved by the present invention is: in order to solve the problems existing in the above-mentioned background technology, a pure electric vehicle creep and anti-slope rolling joint control method applied to the whole vehicle controller is provided to optimize the flexibility of the pure electric vehicle creep and anti-slope rolling control method and ensure the stability of the control method.

[0007] The technical solution adopted by the present invention to solve the technical problem is a pure electric vehicle creeping and anti-slope sliding joint control method applied to a vehicle controller, comprising the following steps: S1, judging whether the driving motor speed n allows the vehicle to creep or anti-slope sliding; S2, judging whether the vehicle creeping or anti-slope sliding is pre-enabled; S3, judging whether the vehicle creeping or anti-slope sliding is enabled; S4, obtaining the values ​​of a and b in the discrete PI algorithm; S5, adjusting the PI output of the VCU using the discrete PI algorithm:

[0008] The calculation method of discrete PI output under the anti-slip state is as follows, where: n k is the driving motor speed of the kth control cycle, u i (k) is the integral link output of the discrete PI algorithm of the kth control cycle;

[0009] In the creeping state, first calculate k p and k i , the method is as follows:

[0010]

[0011] Then obtain the discrete PI output in the creeping state:

[0012]

[0013] S6, multiply the discrete PI output and the output torque result of the drive motor characteristic curve to obtain a preliminary output torque T; S7, further limit the preliminary output torque, and finally obtain the final output torque T after the limit. result Sent to the drive motor and gearbox in the form of CAN message information.

[0014] To further illustrate, in the above technical solution, the judgment method in S1 is:

[0015]

[0016] S=1 indicates that the drive motor rotates forward and allows the vehicle to creep or prevent rolling down a slope, and R=1 indicates that the drive motor rotates reversely and allows the vehicle to creep or prevent rolling down a slope.

[0017] To further illustrate, in the above technical scheme, the method for judging whether creep is pre-enabled in S2 is: the opening of the accelerator pedal and the brake pedal are both less than or equal to 3%; the vehicle speed is less than 6km / h; the handbrake and automatic parking are not activated; the driver's gear request and the transmission are not in neutral; the method for judging whether anti-slope sliding is pre-enabled in S2 is: the opening of the brake pedal is less than or equal to 5%, or the opening is less than or equal to 60% and the change relative to the previous control cycle is less than or equal to 5%; the vehicle speed is less than or equal to 3km / h; the drive motor speed is between -50r / min and 10r / min; the handbrake and automatic parking are not activated; the driver's gear request and the transmission are both in forward gear.

[0018] To further illustrate, in the above technical solution, the method of S3 judging whether the vehicle creeping or anti-slope rolling is enabled is as follows: S11, in the initial state; S22, creeping state; S33, when R=1 and the gearbox is in the forward gear and enters the anti-slope rolling state; S44, when the anti-slope rolling state is pre-enabled and the anti-slope rolling state is maintained for 3 seconds or the anti-slope rolling state is not pre-enabled, the initial state is restored.

[0019] To further illustrate, in the above technical solution, a in S4 is always equal to 0, and the method for obtaining b is: in the creeping state, the initial value of b is 0.1; the timing starts when s is 1, and b is set to 0 after about 5 seconds; after the vehicle enters the creeping state again, b is set to 0.1 again, and then the value of b is obtained repeatedly; in the anti-slope state, the initial value of b is 1; the timing starts when the vehicle enters the anti-slope state, and after about 3 seconds the vehicle enters the initial state and b is set to 0; after the vehicle enters the anti-slope state again, b is set to 1 again, and then the value of b is obtained repeatedly.

[0020] Further explanation, in the above technical solution, the limiting process in S7 is as follows: S111, calculating the torque T that the power battery can supply to the drive motor BatAllow :

[0021]

[0022] Where: P represents power, ω represents the speed of the drive motor, both are international units; S222, combined with TBatAllow and the torque T that the motor itself can provide MotAllow Limit T result ;

[0023] When the throttle opening is less than or equal to 0.1%, the result is recorded as T result小油门开度 :

[0024] T result小油门开度 =min(0.94T,T MotAllow , T BatAllow , 2500)

[0025] When the throttle opening is greater than 0.1%, the result is recorded as T result大油门开度 :

[0026]

[0027] The beneficial effects of the present invention are as follows: the combined control method for creeping and anti-slope rolling of a pure electric vehicle applied to a whole vehicle controller proposed by the present invention optimizes the flexibility of the creeping and anti-slope rolling control method of the pure electric vehicle and ensures the stability of the control method. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a typical driving form of the vehicle to which the present method is applied;

[0030] Figure 2 It is the process of judging whether the vehicle creeping or anti-slope rolling is enabled;

[0031] Figure 3 is a flow chart of the steps of the method;

[0032] Figure 4 The invention discloses a vehicle working flow chart including the vehicle creeping and anti-slope sliding joint control method of the present invention. DETAILED DESCRIPTION

[0033] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] See Figure 1-4 The corresponding vehicle controller control period can be taken as 0.01s.

[0035] See Figure 1 and 4 The example shown is: the vehicle has no faults, starts successfully, and the power battery is not charged externally; the control cycle of this method is 0.01 seconds; the power form of the vehicle platform used is as follows Figure 1 As shown, B represents the power battery, M represents the drive motor, C represents the clutch, GB represents the transmission, and M represents the differential. The clutch and transmission of this platform are integrated into one.

[0036] The first step is to determine whether the drive motor speed n (in r / min, indicating the number of revolutions per minute) allows the vehicle to creep or prevent rolling. S=1 means that the drive motor rotates forward and allows the vehicle to creep or prevent rolling. R=1 means that the drive motor rotates reversely and allows the vehicle to creep or prevent rolling:

[0037]

[0038] The second step is to determine whether the vehicle creep or anti-slope function is pre-enabled.

[0039] Creep pre-enablement is enabled if all of the following conditions are met: the accelerator pedal and brake pedal openings are both less than or equal to 3%; the vehicle speed is less than 6 km / h; the handbrake and automatic parking are not activated; the driver's gear request and the transmission are not in neutral.

[0040] The anti-slope pre-enablement is enabled if all the following conditions are met: the brake pedal opening is less than or equal to 5%, or the opening is less than or equal to 60% and the change relative to the previous control cycle is less than or equal to 5%; the vehicle speed is less than or equal to 3km / h; the drive motor speed is between -50r / min and 10r / min; the handbrake and automatic parking are not activated; the driver's gear request and the transmission are both forward gears.

[0041] The third step is to determine whether the vehicle creep or anti-slip is enabled. Figure 2 shown.

[0042] The fourth step is to find the values ​​of a and b in the discrete PI algorithm. a is always equal to 0, and the method for finding b is:

[0043] In the creeping state, the initial value of b is 0.1. When S is 1, the timing starts, and b is set to 0 after about 5 seconds. When the vehicle enters the creeping state again, b is set to 0.1 again, and the value of b is calculated repeatedly.

[0044] In the anti-slope state, the initial value of b is 1. The timing starts from when the vehicle enters the anti-slope state. After about 3 seconds, the vehicle enters the initial state and b is set to 0. After the vehicle enters the anti-slope state again, b is set to 1 again, and then the value of b is calculated repeatedly.

[0045] Step 5: Use the discrete PI algorithm to adjust the PI output of the VCU:

[0046] The calculation method of discrete PI output under the anti-slip state is as follows, where: n k is the driving motor speed of the kth control cycle, u i (k) is the integral output of the discrete PI algorithm in the kth control cycle:

[0047]

[0048] In the creeping state, first calculate k p and k i , the method is as follows:

[0049]

[0050] Then obtain the discrete PI output in the creeping state:

[0051]

[0052] Step 6: Multiply the discrete PI output and the output torque result of the drive motor characteristic curve to obtain the preliminary output torque T.

[0053] Step 7: Further limit the initial output torque, and finally limit the final output torque T resultIt is sent to the drive motor and gearbox in the form of CAN message information. The restriction process is as follows:

[0054] First, calculate the torque T that the power battery can supply to the drive motor BatAllow , as shown in the following formula. Where: P represents power, ω represents the speed of the drive motor, both are in the international unit system.

[0055]

[0056] Then, combined with T BatAllow and the torque T that the motor itself can provide MotAllow Limit T result When the throttle opening is less than or equal to 0.1%, the result is recorded as T result小油门开度 :

[0057] T result小油门开度 =min(0.94T,T MotAllow , T BatAllo , 2500)

[0058] When the throttle opening is greater than 0.1%, the result is recorded as T result大油门开度 :

[0059]

[0060] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A combined control method for creeping and anti-slope sliding of pure electric vehicles applied to a vehicle controller, characterized in that: The method comprises the following steps: S1, judging whether the driving motor speed n allows the vehicle to creep or prevent the vehicle from sliding down a slope; S2, judging whether the vehicle creep or prevent the vehicle from sliding down a slope is pre-enabled; S3, judging whether the vehicle creep or prevent the vehicle from sliding down a slope is enabled; S4, obtaining the values ​​of a and b in the discrete PI algorithm; S5, adjusting the PI output of the VCU using the discrete PI algorithm: The calculation method of discrete PI output under the anti-slip state is as follows, where: n k is the driving motor speed of the kth control cycle, u i (k) is the integral link output of the discrete PI algorithm of the kth control cycle; In the creeping state, first calculate k p and k i , the method is as follows: Then obtain the discrete PI output in the creeping state: S6, multiply the discrete PI output and the output torque result of the drive motor characteristic curve to obtain a preliminary output torque T; S7, further limit the preliminary output torque, and finally obtain the final output torque T after the limit. result Sent to the drive motor and gearbox in the form of CAN message information.

2. The electric vehicle creep and anti-slope combined control method applied to the vehicle controller as claimed in claim 1 is characterized by: The judgment method in S1 is: S=1 indicates that the drive motor rotates forward and allows the vehicle to creep or prevent rolling down a slope, and R=1 indicates that the drive motor rotates reversely and allows the vehicle to creep or prevent rolling down a slope.

3. The electric vehicle creep and anti-slope joint control method applied to the vehicle controller as claimed in claim 1 is characterized by: The method for determining whether creep is pre-enabled in the S2 is: the opening of the accelerator pedal and the brake pedal are both less than or equal to 3%; the vehicle speed is less than 6km / h; the handbrake and automatic parking are not activated; the driver's gear request and the transmission are not in neutral; the method for determining whether anti-slope rolling is pre-enabled in the S2 is: the brake pedal opening is less than or equal to 5%, or the opening is less than or equal to 60% and the change relative to the previous control cycle is less than or equal to 5%; the vehicle speed is less than or equal to 3km / h; the drive motor speed is between -50r / min and 10r / min; the handbrake and automatic parking are not activated; the driver's gear request and the transmission are both in forward gear.

4. The electric vehicle creep and anti-slope joint control method applied to the vehicle controller as claimed in claim 1 is characterized by: The method of S3 for judging whether the vehicle creeping or anti-slope rolling is enabled is as follows: S11, in the initial state; S22, creeping state; S33, when R=1 and the gearbox is in the forward gear and enters the anti-slope rolling state; S44, when the anti-slope rolling pre-enables and the anti-slope rolling state is maintained for 3 seconds or the anti-slope rolling is not pre-enabled, restore to the initial state.

5. The electric vehicle creep and anti-slope combined control method applied to the vehicle controller as claimed in claim 1, characterized in that: In the above S4, a is always equal to 0, and the method for obtaining b is: In the creeping state, the initial value of b is 0.1; the timing starts when s is 1, and b is set to 0 after about 5 seconds; when the vehicle enters the creeping state again, b is set to 0.1 again, and then the value of b is calculated repeatedly; In the anti-slope state, the initial value of b is 1; the timing starts from when the vehicle enters the anti-slope state, and after about 3 seconds the vehicle enters the initial state and b is set to 0; after the vehicle enters the anti-slope state again, b is set to 1 again, and then the value of b is obtained repeatedly.

6. The electric vehicle creep and anti-slope combined control method applied to the vehicle controller as claimed in claim 1, characterized in that: The limiting process in S7 is as follows: S111, calculating the torque T that the power battery can supply to the drive motor BatAllow : Where: P represents power, ω represents the speed of the drive motor, both are international units; S222, combined with TBatAllow and the torque T that the motor itself can provide MotAllow Limit T result ; When the throttle opening is less than or equal to 0.1%, the result is recorded as T result小油门开度 : T result小油门开度 =min(0.94T,T MotAllow ,T BatAllow ,2500) When the throttle opening is greater than 0.1%, the result is recorded as T result大油门开度 :

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