Pure electric vehicle creeping anti-slip control method applied to vehicle controller

Abstract

The application relates to a pure electric vehicle creeping anti-slip control method applied to a vehicle controller, which comprises the following steps: S1, judging whether the drive motor rotating speed n allows the vehicle to creep or prevents the vehicle from slipping on a slope; S2, judging whether the vehicle creeping or anti-slip on a slope is pre-enabled; S3, judging whether the vehicle creeping or anti-slip on a slope is enabled; S4, obtaining the values of a and b in a discrete PI algorithm; S5, adjusting the PI output of the VCU by using the discrete PI algorithm; S6, multiplying the discrete PI output and the output torque result of the drive motor characteristic curve to obtain a preliminary output torque T; S7, further limiting the preliminary output torque, and finally obtaining the final output torque T result The CAN message information is sent to the drive motor and the gearbox. The pure electric vehicle creeping anti-slip control method applied to the vehicle controller optimizes the flexibility of the pure electric vehicle creeping and anti-slip control method, and guarantees the stability of the control method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of control methods, in particular to a pure electric vehicle creeping anti-slip control method applied to a vehicle controller. BACKGROUND

[0002] An important part of the commonly used control method in the automobile field is a discrete proportional integral derivative algorithm (discrete PID), which has simple principles and is easy to implement:

[0003]

[0004] In the formula, T and k represent the sampling period and the sampling sequence number of the VCU respectively; e(k) represents the difference between the expected value (such as the expected vehicle speed) and the vehicle output (such as the 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 represent the parameters of the proportional, integral and derivative 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 and a and b are constant values, and the flexibility is not enough; the derivative link is easy to introduce high-frequency interference, and the integral link is easy to have large overshoot when e(k) is large, which is not conducive to the stability control of the vehicle. SUMMARY

[0006] The technical problem to be solved by the present application is to solve the problems in the above background art, and to provide a pure electric vehicle creeping anti-slip combined control method applied to a vehicle controller, which optimizes the flexibility of the pure electric vehicle creeping and anti-slip control method and ensures the stability of the control method.

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

[0008] The discrete PI output calculation method in the anti-slip state is as follows, in which: n k is the drive motor speed in the kth control period, u i (k) is the integral link output of the discrete PI algorithm in the kth control period.

[0009] Firstly, k p and k i , the method is as follows:

[0010]

[0011] Then, the discrete PI output in the inching state is obtained:

[0012]

[0013] S6, multiplying the discrete PI output and the output torque result of the driving motor characteristic curve to obtain a preliminary output torque T; S7, further limiting the preliminary output torque, and finally obtaining the final output torque T result The CAN message information is sent to the driving motor and the gearbox.

[0014] Further, in the technical scheme, the S1 judgment method is:

[0015]

[0016] S=1 indicates that the driving motor is in forward rotation and the vehicle is allowed to inch or prevent hill rolling, and R=1 indicates that the driving motor is in reverse rotation and the vehicle is allowed to inch or prevent hill rolling.

[0017] Further, in the technical scheme, the S2 method for judging whether the inching is pre-enabled is that the throttle pedal and the brake pedal opening are less than or equal to 3%; the vehicle speed is less than 6 km / h; the hand brake and the automatic parking are not activated; the driver's gear request and the gearbox are not in neutral; the S2 method for judging whether the hill rolling prevention is pre-enabled is that the brake pedal opening is less than or equal to 5%, or the opening is less than or equal to 60% and the change amount relative to the previous control period is less than or equal to 5%; the vehicle speed is less than or equal to 3 km / h; the driving motor speed is between -50 r / min and 10 r / min; the hand brake and the automatic parking are not activated; the driver's gear request and the gearbox are in forward gear.

[0018] Further, in the technical scheme, the S3 method for judging whether the vehicle is inching or preventing hill rolling is as follows: S11, in the initial state; S22, in the inching state; S33, when R=1 and the gearbox is in forward gear, the hill rolling prevention state is entered; S44, when the hill rolling prevention is pre-enabled and the hill rolling prevention state is maintained for 3 seconds or the hill rolling prevention is not pre-enabled, the initial state is restored.

[0019] Further, in the above technical solution, a is equal to 0 in S4, and the method for obtaining b is as follows: 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; after the vehicle enters the creeping state again, b is set to 0.1 again, and the value of b is obtained by repeating the above steps; in the anti-slip state, the initial value of b is 1; the timing starts when the vehicle enters the anti-slip state, and b is set to 0 after about 3 seconds; after the vehicle enters the anti-slip state again, b is set to 1 again, and the value of b is obtained by repeating the above steps.

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

[0021]

[0022] In the formula, P represents power, and ω represents the speed of the driving motor, both of which are international units; S222, the torque T that the motor itself can provide is combined with TBatAllow MotAllow to limit T result ;

[0023] When the accelerator opening degree 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 accelerator opening degree is greater than 0.1%, the result is recorded as T result大油门开度 :

[0026]

[0027] The application has the beneficial effects that the pure electric vehicle creeping and anti-slip combined control method applied to the vehicle controller optimizes the flexibility of the pure electric vehicle creeping and anti-slip control method, and ensures the stability of the control method. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments described in the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0029] Figure 1 is a typical driving form of a vehicle applying the method;

[0030] Figure 2 is a judgment process whether the vehicle is allowed to creep or prevent hill start;

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

[0032] Figure 4 is a vehicle working flow chart comprising the vehicle creep and hill start prevention combined control method. DETAILED DESCRIPTION

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

[0034] See Figures 1-4 The corresponding vehicle controller control period in

[0035] See Figure 1 and 4 The case shown in the figure: the whole vehicle has no fault, the start is successful, and the power battery is not externally charged; the control period of the method is 0.01 seconds; the power form of the vehicle platform applied is shown in Figure 1 B represents the power battery, M represents the driving motor, C represents the clutch, GB represents the transmission, and M represents the differential. The clutch and transmission of this platform are integrated.

[0036] First, judge whether the driving motor speed n (unit: r / min, representing the number of revolutions per minute) allows the vehicle to creep or prevent hill start. S=1 represents that the driving motor rotates forward and allows the vehicle to creep or prevent hill start, and R=1 represents that the driving motor reverses and allows the vehicle to creep or prevent hill start:

[0037]

[0038] Second, judge whether the vehicle is allowed to creep or prevent hill start.

[0039] The following conditions are met: the throttle pedal and brake pedal opening are less than or equal to 3%; the vehicle speed is less than 6km / h; the hand brake and automatic parking are not activated; the driver's gear request and transmission are not neutral.

[0040] All the following conditions are met, the anti-slippery slope pre-enabled: brake pedal opening is less than or equal to 5%, or the opening is less than or equal to 60% and the amount of change relative to the last control cycle is less than or equal to 5%; vehicle speed is less than or equal to 3km / h; drive motor speed is between -50r / min and 10r / min; hand brake and automatic parking are not activated; driver gear request and gearbox are all in forward gear.

[0041] Third step, to determine whether the vehicle is creeping or anti-slippery slope enabled, the method is as shown in Figure 2

[0042] Fourth step, to obtain the value of a and b in discrete PI algorithm, a is always equal to 0, and the method for obtaining b is as follows:

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

[0044] In the anti-slippery slope state, the initial value of b is 1. The timing starts from the time when the vehicle enters the anti-slippery slope state, and after about 3 seconds, the vehicle enters the initial state and b is set to 0. When the vehicle enters the anti-slippery slope state again, b is set to 1 again, and then the value of b is obtained in a loop.

[0045] Fifth step, adjust the PI output of VCU using discrete PI algorithm:

[0046] The calculation method of discrete PI output in anti-slippery slope state is as follows, where: k n i (k) is the integral element output of the kth control cycle of discrete PI algorithm:

[0047]

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

[0049]

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

[0051]

[0052] Sixth step: multiply the discrete PI output and the output torque result of the drive motor characteristic curve to obtain the preliminary output torque T.

[0053] Seventh step: further limit the preliminary output torque, and finally obtain the final output torque T result ​The CAN message information is sent to the driving motor and the gearbox. The limiting process is as follows:

[0054] First, the torque T BatAllow that the power battery can supply to the driving motor is calculated

[0055]

[0056] Then, the torque T BatAllow is combined with the torque T MotAllow that the motor itself can provide to 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] The above is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art, according to the technical solution and the inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A combined control method for preventing slippage and creeping in pure electric vehicles, applied to the vehicle controller, characterized in that: The steps include: S1, determining whether the drive motor speed n allows for vehicle creep or anti-rollover; S2, determining whether vehicle creep or anti-rollover is pre-enabled; S3, determining whether vehicle creep or anti-rollover is enabled; S4, calculating the values ​​of a and b in the discrete PI algorithm; S5, adjusting the VCU's PI output using the discrete PI algorithm: the calculation method for the discrete PI output under anti-rollover conditions is as follows: ； Where: n k Let u be the speed of the drive motor in the kth control cycle. i (k) is the output of the integral element of the discrete PI algorithm in the kth control cycle; In the creeping state, first calculate k. p and k i The method is as follows: ； Then, the discrete PI output under the creeping state is obtained: ； S6. Multiply the discrete PI output and the output torque result from the drive motor characteristic curve to obtain the preliminary output torque T; S7. Further limit the preliminary output torque, and finally calculate the final output torque T after limitation. result It is sent to the drive motor and gearbox in the form of CAN message information; The determination method in S1 is as follows: ； S=1 indicates that the drive motor rotates in the forward direction and allows the vehicle to crawl or prevent slippage; R=1 indicates that the drive motor rotates in the reverse direction and allows the vehicle to crawl or prevent slippage. In S4, a is always equal to 0. The method for obtaining b is as follows: In the creeping state, the initial value of b is 0.1; when s is 1, the timer starts, and b is set to 0 after about 5 seconds; after the vehicle re-enters the creeping state, b is set to 0.1 again, and the value of b is obtained by repeating the process; in the anti-slip slope state, the initial value of b is 1; the timer starts from when the vehicle enters the anti-slip slope state, and b is set to 0 after about 3 seconds; after the vehicle re-enters the anti-slip slope state, b is set to 1 again, and the value of b is obtained by repeating the process.

2. The combined control method for preventing slippage and creeping in pure electric vehicles applied to the vehicle controller as described in claim 1, characterized in that: The method for determining whether creep is pre-enabled in S2 is as follows: 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 auto hold are not activated; and the driver's gear request and the transmission are not in neutral. The method for determining whether anti-rollover is pre-enabled in S2 is as follows: 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 3 km / h; the drive motor speed is between -50 r / min and 10 r / min; the handbrake and auto hold are not activated; and the driver's gear request and the transmission are both in forward gear.

3. The combined control method for preventing slippage and creeping in pure electric vehicles applied to the vehicle controller as described in claim 1, characterized in that: The method for determining whether vehicle creep or anti-rollover is enabled in S3 is as follows: S11, in the initial state; S22, creep state; S33, when R=1 and the gearbox is in forward gear, enter the anti-rollover state; S44, when anti-rollover is pre-enabled and the anti-rollover state is maintained for 3 seconds, or when anti-rollover is not pre-enabled, return to the initial state.

4. The combined control method for preventing slippage and creeping in pure electric vehicles applied to the vehicle controller as described in claim 1, characterized in that: The limiting process in S7 is as follows: S111, calculate the torque T that the power battery can supply to the drive motor. BatAllow : ； In the formula: Indicates power, The speed of the drive motor is expressed in SI units; S222, combined with T BatAllow and the torque that the motor itself can provide Restrict 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 : 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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