Pure electric vehicle gear shifting control method, system and equipment and medium

Abstract

The invention provides a pure electric vehicle gear shifting control method, system, equipment and medium, and belongs to the technical field of vehicle control, and the method comprises the following steps: obtaining the gradient of an electric vehicle and the opening degree of a brake pedal of the vehicle in the gear shifting process, compensating the speed change of the pure electric vehicle caused by gravity according to the gradient to obtain a dynamic compensation speed, speed change caused by braking is compensated according to the opening degree of a brake pedal, the braking compensation speed is obtained, a basic target rotating speed formula of the pure electric vehicle is optimized according to the dynamic compensation speed and the braking compensation speed, a target rotating speed adjusting formula is obtained, and the target rotating speed is obtained through the target rotating speed adjusting formula; and the input shaft rotating speed of the pure electric vehicle driving system is obtained, the controller is used for adjusting the input shaft rotating speed, and when the control error of the input shaft rotating speed and the target rotating speed reaches a set threshold value, gear shifting operation is conducted on the pure electric vehicle. The gear shifting success rate can be increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle control, and in particular relates to a pure electric vehicle shift control method, system, equipment and medium. Background Art

[0002] As an important part of the automobile transmission system, the automatic mechanical transmission (AMT) plays a key role in improving driving efficiency and riding comfort. The hill shift control of AMT is one of its key technologies. However, under special working conditions, such as ramp driving or sudden changes in driving intention, the existing AMT control strategy has the problem of shift failure under conditions such as ramp shifting and changing driving intention, which is mainly caused by improper output shaft speed control and inaccurate target speed matching. When the AMT shifts gears on a ramp or a flat road with high resistance, if the target speed under normal working conditions is used, it will cause the shift time to be too long and the power to be interrupted, so that the torque difference and speed difference conditions required for gear shifting cannot be met, resulting in shift failure, which may cause serious safety hazards; in addition, when the driver steps on the brake during the gear shift process and changes the driving intention, the existing control strategy may not be able to respond to this change in time, resulting in shift failure, thus affecting the accuracy and reliability of the gear shift. Summary of the invention

[0003] In order to overcome the problem of inaccurate AMT shift control under special working conditions, the present invention provides a pure electric vehicle shift control method, comprising the following steps:

[0004] Obtaining the slope of the electric vehicle when it is traveling on a slope and the brake pedal opening of the vehicle during the gear shifting process, compensating for the speed change of the pure electric vehicle caused by gravity according to the slope to obtain a dynamic compensation speed, compensating for the speed change caused by braking according to the brake pedal opening to obtain a braking compensation speed, optimizing the basic target speed formula of the pure electric vehicle according to the dynamic compensation speed and the braking compensation speed to obtain a target speed adjustment formula, and using the target speed adjustment formula to obtain the target speed;

[0005] The input shaft speed of the pure electric vehicle drive system is obtained, and the input shaft speed is adjusted using a controller. When the control error between the input shaft speed and the target speed reaches a set threshold, the pure electric vehicle is shifted.

[0006] The method of obtaining the input shaft speed of the pure electric vehicle drive system comprises the following steps:

[0007] Obtain a mass model of a pure electric vehicle, and calculate the current vehicle mass in real time according to the mass model of the pure electric vehicle;

[0008] Obtain constant parameters of the pure electric vehicle, calculate the rolling resistance, air resistance and slope resistance of the pure electric vehicle according to the constant parameters and the current vehicle mass, and calculate the total resistance of the pure electric vehicle according to the rolling resistance, air resistance and slope resistance;

[0009] The motor-related parameters are obtained, and the motor speed, that is, the input shaft speed, is obtained according to the total resistance of the pure electric vehicle and the motor-related parameters.

[0010] Preferably, the step of obtaining the motor-related parameters and obtaining the motor speed according to the total resistance of the pure electric vehicle and the motor-related parameters comprises the following steps:

[0011] Obtaining motor efficiency, and calculating motor torque according to the motor efficiency and the total resistance;

[0012] Obtain the motor torque constant, and calculate the motor current based on the motor torque constant and the motor torque;

[0013] Obtain the motor back electromotive force constant, calculate the theoretical speed of the motor according to the back electromotive force constant and the motor current, calculate the motor power according to the theoretical speed of the motor and the motor torque, calculate the motor voltage according to the motor back electromotive force constant and the theoretical speed of the motor, and obtain the motor speed according to the motor power and the motor voltage.

[0014] Preferably, the method of obtaining the slope of the pure electric vehicle when driving on a slope is specifically as follows: collecting acceleration values ​​of the pure electric vehicle in the forward, lateral and vertical directions through a three-axis acceleration sensor, and calculating the slope of the pure electric vehicle through the acceleration values ​​of the pure electric vehicle in the forward, lateral and vertical directions.

[0015] Preferably, the target speed adjustment formula is as follows:

[0016] ω 2 =Rv current / 60+k grade sin(θ)-k brake ω brake ,

[0017] Where R is the transmission ratio of the target gear, v current is the current vehicle speed, m / s or km / h, k grade is the vehicle performance and slope adjustment coefficient, k brake is the braking intensity adjustment coefficient, θ is the slope angle, ω brake is the brake pedal opening.

[0018] Preferably, the mass model of the pure electric vehicle is specifically:

[0019] m=0.337·T elec ·n elec / (g·f r +g·i+C d ·A·v 2 / 2),

[0020] Where, T elec is the rated torque of the motor, n elec is the motor speed, g is the acceleration due to gravity, f r is the road rolling resistance coefficient, i is the road slope, C d is the vehicle's air resistance coefficient, A is the vehicle's forward windward area, and v is the vehicle's speed.

[0021] The present invention also provides a pure electric vehicle shift control system, comprising:

[0022] A target speed adjustment module is used to obtain the slope of the electric vehicle when it is driving on a slope and the brake pedal opening of the vehicle during the gear shifting process, compensate the speed change of the pure electric vehicle caused by gravity according to the slope, obtain the dynamic compensation speed, compensate the speed change caused by braking according to the brake pedal opening, obtain the braking compensation speed, optimize the basic target speed formula of the pure electric vehicle according to the dynamic compensation speed and the braking compensation speed, obtain the target speed adjustment formula, and use the target speed adjustment formula to obtain the target speed;

[0023] The shift control module is used to obtain the input shaft speed of the pure electric vehicle drive system, use the controller to adjust the input shaft speed, and perform a shift operation on the pure electric vehicle when the control error between the input shaft speed and the target speed reaches a set threshold.

[0024] The present invention also provides a computer device, including a memory and a processor; the memory stores a computer program, and the processor is used to run the computer program in the memory to execute the pure electric vehicle shift control method.

[0025] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program is suitable for being loaded by a processor to execute the pure electric vehicle shift control method.

[0026] The pure electric vehicle shift control method provided by the present invention has the following beneficial effects:

[0027] The present invention can compensate for the dynamic compensation speed and braking compensation speed of the pure electric vehicle by acquiring the slope and brake pedal opening of the electric vehicle in real time; the dynamic compensation speed can compensate for the speed change of the pure electric vehicle caused by gravity when driving on a slope, and the braking compensation speed can compensate for the speed change of the pure electric vehicle caused by braking when changing the driving intention, thereby dynamically adjusting the target speed; by controlling the input shaft speed of the pure electric vehicle drive system within the control error range of the target speed to perform gear shifting operations on the pure electric vehicle, the gear shifting success rate when driving on a slope and changing the driving intention can be greatly improved to meet the needs of different working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiment of the present invention and its design scheme, the following briefly introduces the drawings required for this embodiment. The drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 This is a flow chart of a pure electric vehicle shift control method according to an embodiment of the present invention;

[0030] Figure 2 Calculate the target speed logic diagram;

[0031] Figure 3 This is the logic diagram for motor speed calculation. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the scope of protection of the present invention.

[0033] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the technical solutions of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0034] In addition, the terms "first", "second", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance. In the description of the present invention, it should be noted that, unless otherwise clearly specified or limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. In the description of the present invention, unless otherwise specified, "plurality" means two or more, which will not be described in detail here.

[0035] Example

[0036] The present invention provides a pure electric vehicle shift control method, specifically as follows Figure 1 As shown, the following steps are included:

[0037] Step 1: Obtain the slope of the electric vehicle when it is driving on a slope and the brake pedal opening of the vehicle during the gear shifting process. Compensate the speed change of the pure electric vehicle caused by gravity according to the slope to obtain the dynamic compensation speed. Compensate the speed change caused by braking according to the brake pedal opening to obtain the braking compensation speed. Optimize the basic target speed formula of the pure electric vehicle according to the dynamic compensation speed and the braking compensation speed to obtain the target speed adjustment formula, and use the target speed adjustment formula to obtain the target speed. The specific steps are as follows (such as Figure 2 shown):

[0038] (1) The basic target speed formula can be calculated based on the current vehicle speed and transmission ratio as follows:

[0039] ω=Rv current / 60;

[0040] Among them, R is the transmission ratio of the target gear, v current is the current vehicle speed, m / s or km / h, ω is the basic target speed (i.e. theoretical speed), and 60 is used to convert the vehicle speed (assuming km / h) into a unit that matches the speed.

[0041] (2) Obtain the slope of the electric vehicle when it is driving on a slope. The details are as follows:

[0042] Install a three-axis acceleration sensor: A three-axis acceleration sensor is installed in the controller to measure the vehicle's acceleration in the forward direction (X-axis), lateral direction (Y-axis), and vertical direction (Z-axis).

[0043] Angle and acceleration conversion: The acceleration value measured by the three-axis acceleration sensor is converted into the vehicle's tilt angle (i.e. slope angle) through a formula. The conversion formula is as follows:

[0044] θ = arcsin(X);

[0045] θ = arctan(X / Z);

[0046] Where θ is the inclination angle of the vehicle relative to the horizontal plane (i.e., the slope angle), and X and Z are the output values ​​of the acceleration sensor in the X-axis and Z-axis directions.

[0047] (2) Obtain dynamic compensation speed.

[0048] When a pure electric vehicle is driving on a slope, the influence of the slope needs to be considered. The target speed is adjusted according to the slope to compensate for the speed change caused by gravity and obtain a dynamic compensation speed, as follows:

[0049] ω 21 =ω+k grade sin(θ);

[0050] Among them, k grade It is a factor adjusted according to vehicle performance and slope.

[0051] (3) Obtain the braking compensation speed.

[0052] When braking during the gear shifting process, considering the impact of braking, the target speed needs to be lowered to adapt to the change in driving intention, and the braking compensation speed is obtained as follows:

[0053] ω 22 =ω-k brake ω brake ;

[0054] Among them, k brake is a coefficient adjusted according to the braking intensity, ω brake is the brake pedal opening.

[0055] By combining the above factors, the target speed adjustment formula is obtained, which is:

[0056] ω 2 =Rv current / 60+k grade sin(θ)-k brake ω brake ;

[0057] Where R is the transmission ratio of the target gear, v current is the current vehicle speed, m / s or km / h, k grade is the vehicle performance and slope adjustment coefficient, k brake is the braking intensity adjustment coefficient, θ is the slope angle, ω brake is the brake pedal opening.

[0058] For the coefficient k in the formula grade and k brake , need to be adjusted based on actual test results, and these coefficients may depend on vehicle weight, powertrain characteristics and driving style.

[0059] Step 2: Obtain the input shaft speed of the pure electric vehicle drive system, use the controller to adjust the input shaft speed, and perform a gear shift operation on the pure electric vehicle when the control error between the input shaft speed and the target speed reaches a set threshold. The specific steps include:

[0060] (1) Obtain the input shaft speed of the pure electric vehicle drive system, such as Figure 3 shown.

[0061] (1.1) Define vehicle constant parameters.

[0062] m: vehicle mass (kg);

[0063] g: acceleration due to gravity (m / s 2 );

[0064] ρ: air density (kg / m 3 );

[0065] A: Vehicle front projection area (m 2 );

[0066] C d : air resistance coefficient;

[0067] μ: rolling resistance coefficient;

[0068] K t : Motor torque constant (Nm / A);

[0069] Ke: Motor back electromotive force constant (V / rad / s or V / rpm);

[0070] η: motor efficiency;

[0071] V: Motor supply voltage (V).

[0072] (1.2) Obtain the mass model of the pure electric vehicle, and calculate the current vehicle mass in real time based on the mass model of the pure electric vehicle. The mass model of the pure electric vehicle is as follows:

[0073] m=0.337·T elec ·n elec / (g·f r +g·i+C d ·A·v 2 / 2);

[0074] Where, T elecis the rated torque of the motor, n elec is the motor speed, g is the acceleration due to gravity, f r is the road rolling resistance coefficient, i is the road slope, C d is the vehicle's air resistance coefficient, A is the vehicle's forward windward area, and v is the vehicle's speed.

[0075] (1.3) Calculate the resistance.

[0076] Rolling resistance F roll =μmg;

[0077] Air resistance F air =1 / 2ρAC d v 2 ;

[0078] Slope resistance F grade =mgsin(θ).

[0079] (1.4) Calculate the total resistance.

[0080] F total =F roll +F air +F grade .

[0081] (1.5) Calculate the required motor torque.

[0082] Calculate the motor torque T required to overcome the total resistance and achieve the desired acceleration:

[0083] T=F total / η.

[0084] (1.6) Calculate the motor current.

[0085] According to the motor torque constant K t and the required motor torque T to calculate the motor current I:

[0086] I=T / K t .

[0087] (1.7) Calculate the motor speed.

[0088] Use the motor back EMF constant K e and the motor current I to estimate the motor speed ω 1 (i.e. input shaft speed). The specific process is as follows:

[0089] The power P of the motor is:

[0090] P = Tω;

[0091] The voltage V of the motor is:

[0092] V=Ke ω;

[0093] Therefore, the motor speed ω 1 It can be estimated by motor power P and voltage V:

[0094] ω 1 =P / V.

[0095] (2) A controller is used to adjust the input shaft speed so that the input shaft speed responds to changes in the target speed. When the control error between the input shaft speed and the target speed reaches a set threshold, the pure electric vehicle is shifted.

[0096] In order to improve the success rate of gear shifting, PID (proportional-integral-differential) control is used to optimize the control of the target speed. By adjusting the PID control parameters, the input shaft speed can respond to the target speed more quickly, thereby improving the success rate of gear shifting.

[0097] The PID controller calculates the control quantity through three parts: proportional (P), integral (I), and differential (D) to reduce the system error.

[0098] The PID control formula is: u(t) = K p e(t)+K i ∫e(t)dt+K d de(t) / dt;

[0099] Among them, u(t) is the control input, e(t) is the error (the difference between the target speed and the current speed), K p , K i , K d They are proportional, integral, and differential gains respectively.

[0100] Proportional control: Directly adjust the control input based on the current speed error. Integral control: Consider the accumulation of error over time to eliminate steady-state error. Derivative control: Predict the trend of error changes to improve the response speed and stability of the system. Calculate the PID control output based on the real-time measured vehicle state and target speed, and adjust the control input of the motor.

[0101] The adjustment of target speed and PID control optimization are interrelated. The adjustment of target speed is to adapt to special working conditions, while PID control optimization is to ensure that the speed of the input shaft can respond quickly and accurately to changes in target speed. Through these control strategies, the AMT system can achieve smooth and accurate shifting operations under various working conditions.

[0102] The present invention also provides a pure electric vehicle shift control system, comprising:

[0103] A target speed adjustment module is used to obtain the slope of the electric vehicle when it is driving on a slope and the brake pedal opening of the vehicle during the gear shifting process, compensate the speed change of the pure electric vehicle caused by gravity according to the slope, obtain the dynamic compensation speed, compensate the speed change caused by braking according to the brake pedal opening, obtain the braking compensation speed, optimize the basic target speed formula of the pure electric vehicle according to the dynamic compensation speed and the braking compensation speed, obtain the target speed adjustment formula, and use the target speed adjustment formula to obtain the target speed;

[0104] The shift control module is used to obtain the input shaft speed of the pure electric vehicle drive system, use the controller to adjust the input shaft speed, and perform a shift operation on the pure electric vehicle when the control error between the input shaft speed and the target speed reaches a set threshold.

[0105] The present invention also provides a computer device, including a memory and a processor; the memory stores a computer program, and the processor is used to run the computer program in the memory to execute the pure electric vehicle shift control method.

[0106] The present invention also provides a computer-readable storage medium, which stores a computer program. The computer program is suitable for loading into a processor to execute a pure electric vehicle shift control method.

[0107] The embodiments described above are only preferred specific implementation modes of the present invention, and the protection scope of the present invention is not limited thereto. Any simple changes or equivalent replacements of the technical solutions that can be obviously obtained by any technician familiar with the field within the technical scope disclosed in the present invention belong to the protection scope of the present invention.

Claims

1. A pure electric vehicle shift control method, characterized in that: The steps include: Obtaining the slope of the electric vehicle when it is traveling on a slope and the brake pedal opening of the vehicle during the gear shifting process, compensating for the speed change of the pure electric vehicle caused by gravity according to the slope to obtain a dynamic compensation speed, compensating for the speed change caused by braking according to the brake pedal opening to obtain a braking compensation speed, optimizing the basic target speed formula of the pure electric vehicle according to the dynamic compensation speed and the braking compensation speed to obtain a target speed adjustment formula, and using the target speed adjustment formula to obtain the target speed; The input shaft speed of the pure electric vehicle drive system is obtained, and the input shaft speed is adjusted using a controller. When the control error between the input shaft speed and the target speed reaches a set threshold, the pure electric vehicle is shifted.

2. The pure electric vehicle shift control method according to claim 1, characterized in that: The method of obtaining the input shaft speed of the pure electric vehicle drive system comprises the following steps: Obtain a mass model of a pure electric vehicle, and calculate the current vehicle mass in real time according to the mass model of the pure electric vehicle; Obtain constant parameters of the pure electric vehicle, calculate the rolling resistance, air resistance and slope resistance of the pure electric vehicle according to the constant parameters and the current vehicle mass, and calculate the total resistance of the pure electric vehicle according to the rolling resistance, air resistance and slope resistance; The motor-related parameters are obtained, and the motor speed, that is, the input shaft speed, is obtained according to the total resistance of the pure electric vehicle and the motor-related parameters.

3. The pure electric vehicle shift control method according to claim 2, characterized in that: The step of obtaining the motor-related parameters and obtaining the motor speed according to the total resistance of the pure electric vehicle and the motor-related parameters comprises the following steps: Obtaining motor efficiency, and calculating motor torque according to the motor efficiency and the total resistance; Obtain the motor torque constant, and calculate the motor current based on the motor torque constant and the motor torque; Obtain the motor back electromotive force constant, calculate the theoretical speed of the motor according to the back electromotive force constant and the motor current, calculate the motor power according to the theoretical speed of the motor and the motor torque, calculate the motor voltage according to the motor back electromotive force constant and the theoretical speed of the motor, and obtain the motor speed according to the motor power and the motor voltage.

4. The pure electric vehicle shift control method according to claim 1, characterized in that: The method of obtaining the slope of the pure electric vehicle when driving on a slope is specifically as follows: collecting acceleration values ​​of the pure electric vehicle in the forward direction, lateral direction and vertical direction through a three-axis acceleration sensor, and calculating the slope of the pure electric vehicle through the acceleration values ​​of the pure electric vehicle in the forward direction, lateral direction and vertical direction.

5. The pure electric vehicle shift control method according to claim 1, characterized in that: The target speed adjustment formula is as follows: ω2=Rv current / 60+k grade sin(θ)-k brake oh brake , Where R is the transmission ratio of the target gear, v current is the current vehicle speed, m / s or km / h, k grade is the vehicle performance and slope adjustment coefficient, k brake is the braking intensity adjustment coefficient, θ is the slope angle, ω brake is the brake pedal opening.

6. The pure electric vehicle shift control method according to claim 2, characterized in that: The mass model of the pure electric vehicle is specifically: m=0.337·T elec ·n elec / (g·f r +g·i+C d ·A·v 2 / 2), Formula, T elec is the rated torque of the motor, n elec is the motor speed, g is the acceleration due to gravity, f r is the road rolling resistance coefficient, i is the road slope, C d is the vehicle's air resistance coefficient, A is the vehicle's forward windward area, and v is the vehicle's speed.

7. A pure electric vehicle shift control system, characterized in that: include: A target speed adjustment module is used to obtain the slope of the electric vehicle when it is driving on a slope and the brake pedal opening of the vehicle during the gear shifting process, compensate the speed change of the pure electric vehicle caused by gravity according to the slope, obtain the dynamic compensation speed, compensate the speed change caused by braking according to the brake pedal opening, obtain the braking compensation speed, optimize the basic target speed formula of the pure electric vehicle according to the dynamic compensation speed and the braking compensation speed, obtain the target speed adjustment formula, and use the target speed adjustment formula to obtain the target speed; The shift control module is used to obtain the input shaft speed of the pure electric vehicle drive system, use the controller to adjust the input shaft speed, and perform a shift operation on the pure electric vehicle when the control error between the input shaft speed and the target speed reaches a set threshold.

8. A computer device, characterized in that: It comprises a memory and a processor; the memory stores a computer program, and the processor is used to run the computer program in the memory to execute the pure electric vehicle shift control method as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is suitable for being loaded by a processor to execute the pure electric vehicle shift control method according to any one of claims 1 to 6.

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