阅读说明：本技术 一种电动汽车自动变速箱换挡控制方法 (Gear shifting control method for automatic gearbox of electric automobile ) 是由 晏萌 彭凯 李大威 郭启翔 刘磊 余平兰 白世伟 吴明瞭 尹思维 于 2021-01-08 设计创作，主要内容包括：一种电动汽车自动变速箱换挡控制方法,首先在整车需要换挡时进行第一次路况判断,然后在整车满足换挡条件时依次控制驱动电机转矩清零、控制换挡电机摘挡、控制驱动电机调速、控制换挡电机挂挡,其次进行第二次路况判断,再通过比较第一次路况判断结果、第二次路况判断结果得到实际路况并根据实际路况计算得到驱动电机目标转矩,最后将驱动电机转矩调整至目标转矩,换挡完成。该方法不仅通过实际路况计算得到驱动电机的目标转矩,使得驱动电机转矩能够随实际路况的变化而变化,提高了换挡平顺性,驾驶体验好,而且通过将两次路况判断结果相比较以确定实际路况,避免了对路况的误判,可靠性较高。(A gear shifting control method for an automatic gearbox of an electric automobile comprises the steps of firstly judging the first road condition when the whole automobile needs to be shifted, then sequentially controlling the torque of a driving motor to be reset, controlling the gear shifting motor to be shifted, controlling the speed of the driving motor to be adjusted and controlling the gear shifting motor to be shifted when the whole automobile meets a gear shifting condition, secondly judging the second road condition, then obtaining the actual road condition by comparing the first road condition judgment result with the second road condition judgment result, calculating according to the actual road condition to obtain the target torque of the driving motor, finally adjusting the torque of the driving motor to the target torque, and finishing gear shifting. According to the method, the target torque of the driving motor is obtained through actual road condition calculation, so that the torque of the driving motor can change along with the change of the actual road condition, the gear shifting smoothness is improved, the driving experience is good, the actual road condition is determined by comparing the judging results of the two road conditions, the misjudgment of the road condition is avoided, and the reliability is high.)

1. A gear shifting control method for an automatic gearbox of an electric automobile is characterized by comprising the following steps:

the control method sequentially comprises the following steps:

s1, the gearbox controller judges whether the whole vehicle needs to be shifted, if yes, a shifting request is sent to the whole vehicle controller, and first road condition judgment is carried out;

s2, the vehicle controller judges whether the vehicle meets a gear shifting condition according to the gear shifting request, and if so, the vehicle controller is driven to enter a control mode of a gearbox controller;

s3, the gearbox controller firstly controls the driving motor controller to clear the torque of the driving motor and then controls the gear shifting motor to disengage;

s4, firstly, the gearbox controller sends the target rotating speed of the driving motor to the driving motor controller, and then the driving motor controller regulates the speed of the driving motor according to the target rotating speed of the driving motor until the differential speed between the regulated rotating speed of the driving motor and the target rotating speed of the driving motor is qualified;

s5, the gearbox controller firstly controls the gear shifting motor to engage in a gear, then carries out second road condition judgment, obtains an actual road condition by comparing a second road condition judgment result with a first road condition judgment result, and finally obtains a driving motor target torque by calculation according to the actual road condition;

s6, the gearbox controller firstly controls the driving motor controller to adjust the torque of the driving motor to a target torque, and then sends a gear shifting completion signal to the vehicle control unit;

and S7, the driving motor controller enters a control mode of the whole vehicle controller.

2. The method for controlling the gear shifting of the automatic gearbox of the electric automobile according to claim 1, characterized in that:

in step S1, the first road condition judgment specifically includes: and the gearbox controller brings the measured speed of the whole vehicle and the wheel torque into a road gradient-speed of the whole vehicle-wheel torque MAP calibrated in advance to obtain the road gradient, so that whether the current road condition is an uphill road condition, a downhill road condition or a flat road condition is determined.

3. The method for controlling the gear shifting of the automatic gearbox of the electric automobile according to claim 2, characterized in that:

in step S5, the second road condition judgment specifically includes: the speed changing box controller obtains the wheel speed change rate through the whole vehicle wheel speed calculation obtained through the wheel speed sensor signal, if the wheel speed change rate is a negative value and the absolute value of the wheel speed change rate is larger than a first set threshold value K₁Judging that the current road condition is an uphill road condition, and if the wheel speed change rate is a positive value and the absolute value of the wheel speed change rate is greater than a second set threshold value K₂If not, the current road condition is judged to be a level road condition.

4. The method for controlling the gear shifting of the automatic gearbox of the electric automobile according to the claim 3, characterized in that:

in step S5, the method for comparing the second road condition judgment result with the first road condition judgment result is as follows: and if the second road condition judgment result is the same as the first road condition judgment result, taking the first road condition judgment result as the actual road condition, and if the second road condition judgment result is different from the first road condition judgment result, taking the open road condition as the actual road condition.

5. The method for controlling the gear shifting of the automatic gearbox of the electric automobile according to any one of claims 2-4, characterized in that:

in step S5, the step of calculating the target torque of the drive motor specifically includes: firstly, establishing a target torque calculation function according to the speed of the whole vehicle, and then calculating through the target torque calculation function according to the actual road condition to obtain the target torque of the driving motor;

wherein the target torque calculation function is:

T＝P_e*9550*X/n

in the above formula, T is the target torque, P_eFor the power of the drive motor, X is a weighting coefficient, n is the rotational speed of the drive motor, η_TFor transmission system efficiency, G is the overall vehicle gravity, f is the rolling resistance coefficient, u_aAs the speed of the vehicle, C_DIs an air resistance coefficient, A is a windward area, i is a road gradient, delta is a mass conversion coefficient, m is the vehicle mass,and the X is obtained by substituting the road gradient and the actual road condition into a pre-calibrated actual road condition-road gradient-weighting coefficient MAP.

6. The method for controlling the gear shifting of the automatic gearbox of the electric automobile according to any one of claims 1-4, characterized in that:

in step S2, the shift condition is specifically: the speed of the whole vehicle does not exceed the maximum speed V of the whole vehicle_maxAnd the rotating speed of the driving motor reaches the gear shifting rotating speed n_N。

7. The method for controlling the gear shifting of the automatic gearbox of the electric automobile according to any one of claims 1-4, characterized in that:

in step S3, the determination condition for the drive motor torque zero clearing is: the torque of the driving motor is less than a third set threshold value T_c。

8. The method for controlling the gear shifting of the automatic gearbox of the electric automobile according to any one of claims 1-4, characterized in that:

in step S4, the qualified determination condition of the differential speed between the speed-regulated driving motor speed and the target driving motor speed is: the difference value between the rotating speed of the driving motor after speed regulation and the target rotating speed of the driving motor is smaller than a fourth set threshold value n_c。

Technical Field

The invention belongs to the technical field of new energy automobiles, and particularly relates to a gear shifting control method of an automatic gearbox of an electric automobile, which is suitable for improving the gear shifting smoothness of the electric automobile.

Background

With the rise of new energy industries, the application of electric automobile technology is also wider and wider, the torque required by an electric automobile when going up a slope is larger, and the torque required when going down a slope is smaller, however, the electric automobile mostly adopts a transmission structure without a clutch, the judgment and implementation of gear shifting are completely electronic, the output torque is limited by a controller and cannot be changed, so that the climbing power is insufficient or the speed of the slope is faster, the gear shifting smoothness is lower, and the driving experience is poor. Therefore, there is a problem that the gear shifting smoothness is poor.

Disclosure of Invention

The invention aims to overcome the problems in the prior art and provides a gear shifting control method of an automatic gearbox of an electric automobile with higher gear shifting smoothness.

In order to achieve the above purpose, the invention provides the following technical scheme:

a gear shifting control method for an automatic gearbox of an electric automobile sequentially comprises the following steps:

s1, the gearbox controller judges whether the whole vehicle needs to be shifted, if yes, a shifting request is sent to the whole vehicle controller, and first road condition judgment is carried out;

s2, the vehicle controller judges whether the vehicle meets a gear shifting condition according to the gear shifting request, and if so, the vehicle controller is driven to enter a control mode of a gearbox controller;

s3, the gearbox controller firstly controls the driving motor controller to clear the torque of the driving motor and then controls the gear shifting motor to disengage;

s4, firstly, the gearbox controller sends the target rotating speed of the driving motor to the driving motor controller, and then the driving motor controller regulates the speed of the driving motor according to the target rotating speed of the driving motor until the differential speed between the regulated rotating speed of the driving motor and the target rotating speed of the driving motor is qualified;

s5, the gearbox controller firstly controls the gear shifting motor to engage in a gear, then carries out second road condition judgment, obtains an actual road condition by comparing a second road condition judgment result with a first road condition judgment result, and finally obtains a driving motor target torque by calculation according to the actual road condition;

s6, the gearbox controller firstly controls the driving motor controller to adjust the torque of the driving motor to a target torque, and then sends a gear shifting completion signal to the vehicle control unit;

and S7, the driving motor controller enters a control mode of the whole vehicle controller.

In step S1, the first road condition judgment specifically includes: and the gearbox controller brings the measured speed of the whole vehicle and the wheel torque into a road gradient-speed of the whole vehicle-wheel torque MAP calibrated in advance to obtain the road gradient, so that whether the current road condition is an uphill road condition, a downhill road condition or a flat road condition is determined.

In step S5, the second road condition judgment specifically includes: the speed changing box controller obtains the wheel speed change rate through the whole vehicle wheel speed calculation obtained through the wheel speed sensor signal, if the wheel speed change rate is a negative value and the absolute value of the wheel speed change rate is larger than a first set threshold value K₁Judging that the current road condition is an uphill road condition, and if the wheel speed change rate is a positive value and the absolute value of the wheel speed change rate is greater than a second set threshold value K₂If not, the current road condition is judged to be a level road condition.

In step S5, the method for comparing the second road condition judgment result with the first road condition judgment result is as follows: and if the second road condition judgment result is the same as the first road condition judgment result, taking the first road condition judgment result as the actual road condition, and if the second road condition judgment result is different from the first road condition judgment result, taking the open road condition as the actual road condition.

In step S5, the step of calculating the target torque of the drive motor specifically includes: firstly, establishing a target torque calculation function according to the speed and the transmission ratio of the whole vehicle, and then calculating through the target torque calculation function according to the road gradient to obtain the target torque of the driving motor;

wherein the target torque calculation function is:

T＝P_e*9550*X/n

in the above formula, T is the target torque, P_eFor the power of the drive motor, X is a weighting coefficient, n is the rotational speed of the drive motor, η_TFor transmission system efficiency, G is the overall vehicle gravity, f is the rolling resistance coefficient, u_aAs the speed of the vehicle, C_DIs an air resistance coefficient, A is a windward area, i is a road gradient, delta is a mass conversion coefficient, m is the vehicle mass,and the X is obtained by substituting the road gradient and the actual road condition into a pre-calibrated actual road condition-road gradient-weighting coefficient MAP.

In step S2, the shift condition is specifically: the speed of the whole vehicle does not exceed the maximum speed V of the whole vehicle_maxAnd the rotating speed of the driving motor reaches the gear shifting rotating speed n_N。

In step S3, the determination condition for the drive motor torque zero clearing is: the torque of the driving motor is less than a third set threshold value T_c。

In step S4, the qualified determination condition of the differential speed between the speed-regulated driving motor speed and the target driving motor speed is: the difference value between the rotating speed of the driving motor after speed regulation and the target rotating speed of the driving motor is smaller than a fourth set threshold value n_c。

Compared with the prior art, the invention has the beneficial effects that:

the invention relates to a gear-shifting control method of an automatic gearbox of an electric automobile, which comprises the steps of firstly judging the first road condition when the whole automobile needs to be shifted, then sequentially carrying out torque zero clearing on a driving motor when the whole automobile meets the gear-shifting condition, picking up a gear of the gear-shifting motor, regulating the speed of the driving motor, secondly judging the second road condition, obtaining the actual road condition by comparing the first road condition judgment result and the second road condition judgment result, calculating according to the actual road condition to obtain the target torque of the driving motor, finally adjusting the torque of the driving motor to the target torque after controlling the gear-shifting motor to be shifted, and finishing gear shifting. The misjudgment of the road condition is avoided, and the reliability is high. Therefore, the invention not only improves the gear shifting smoothness, but also has higher reliability.

Drawings

FIG. 1 is a flow chart of the present invention.

Detailed Description

The present invention will be further described with reference to the following embodiments.

Referring to fig. 1, a gear shifting control method for an automatic transmission of an electric vehicle sequentially comprises the following steps:

s1, the gearbox controller judges whether the whole vehicle needs to be shifted, if yes, a shifting request is sent to the whole vehicle controller, and first road condition judgment is carried out;

s2, the vehicle controller judges whether the vehicle meets a gear shifting condition according to the gear shifting request, and if so, the vehicle controller is driven to enter a control mode of a gearbox controller;

s3, the gearbox controller firstly controls the driving motor controller to clear the torque of the driving motor and then controls the gear shifting motor to disengage;

s4, firstly, the gearbox controller sends the target rotating speed of the driving motor to the driving motor controller, and then the driving motor controller regulates the speed of the driving motor according to the target rotating speed of the driving motor until the differential speed between the regulated rotating speed of the driving motor and the target rotating speed of the driving motor is qualified;

s5, the gearbox controller firstly controls the gear shifting motor to engage in a gear, then carries out second road condition judgment, obtains an actual road condition by comparing a second road condition judgment result with a first road condition judgment result, and finally obtains a driving motor target torque by calculation according to the actual road condition;

s6, the gearbox controller firstly controls the driving motor controller to adjust the torque of the driving motor to a target torque, and then sends a gear shifting completion signal to the vehicle control unit;

and S7, the driving motor controller enters a control mode of the whole vehicle controller.

In step S1, the first road condition judgment specifically includes: and the gearbox controller brings the measured speed of the whole vehicle and the wheel torque into a road gradient-speed of the whole vehicle-wheel torque MAP calibrated in advance to obtain the road gradient, so that whether the current road condition is an uphill road condition, a downhill road condition or a flat road condition is determined.

In step S5, the second road condition judgment specifically includes: the speed changing box controller obtains the wheel speed change rate through the whole vehicle wheel speed calculation obtained through the wheel speed sensor signal, if the wheel speed change rate is a negative value and the absolute value of the wheel speed change rate is larger than a first set threshold value K₁Judging that the current road condition is an uphill road condition, and if the wheel speed change rate is a positive value and the absolute value of the wheel speed change rate is greater than a second set threshold value K₂If not, the current road condition is judged to be a level road condition.

In step S5, the method for comparing the second road condition judgment result with the first road condition judgment result is as follows: and if the second road condition judgment result is the same as the first road condition judgment result, taking the first road condition judgment result as the actual road condition, and if the second road condition judgment result is different from the first road condition judgment result, taking the open road condition as the actual road condition.

In step S5, the step of calculating the target torque of the drive motor specifically includes: firstly, establishing a target torque calculation function according to the speed and the transmission ratio of the whole vehicle, and then calculating through the target torque calculation function according to the road gradient and the actual road condition to obtain the target torque of the driving motor;

wherein the target torque calculation function is:

T＝P_e*9550*X/n

in the above formula, T is the target torque, P_eFor the power of the drive motor, X is a weighting coefficient, n is the rotational speed of the drive motor, η_TFor transmission system efficiency, G is the overall vehicle gravity, f is the rolling resistance coefficient, u_aAs the speed of the vehicle, C_DIs an air resistance coefficient, A is a windward area, i is a road gradient, delta is a mass conversion coefficient, m is the vehicle mass,and the X is obtained by substituting the road gradient and the actual road condition into a pre-calibrated actual road condition-road gradient-weighting coefficient MAP.

In step S2, the shift condition is specifically: the speed of the whole vehicle does not exceed the maximum speed V of the whole vehicle_maxAnd the rotating speed of the driving motor reaches the gear shifting rotating speed n_N。

In step S3, the determination condition for the drive motor torque zero clearing is: the torque of the driving motor is less than a third set threshold value T_c。

In step S4, the qualified determination condition of the differential speed between the speed-regulated driving motor speed and the target driving motor speed is: the difference value between the rotating speed of the driving motor after speed regulation and the target rotating speed of the driving motor is smaller than a fourth set threshold value n_c。

The principle of the invention is illustrated as follows:

according to the gear shifting control method of the automatic gearbox of the electric automobile, gear shifting and actual road conditions are combined, and target torques of the driving motor are different under different actual road conditions, so that driving smoothness is improved, and driving experience is good.

Example 1:

referring to fig. 1, a gear shifting control method for an automatic transmission of an electric vehicle sequentially comprises the following steps:

s1, the gearbox controller judges whether the whole vehicle needs to be shifted, if yes, a shifting request is sent to the whole vehicle controller, and first road condition judgment is carried out;

wherein, the first road condition judgment specifically comprises: the gearbox controller brings the measured speed of the whole vehicle and the wheel torque into a road gradient-speed of the whole vehicle-wheel torque MAP which is calibrated in advance to obtain the road gradient, so that whether the current road condition is an uphill road condition, a downhill road condition or a flat road condition is determined;

s2, the vehicle control unit judges whether the whole vehicle meets a gear shifting condition according to the gear shifting request, if so, the motor control unit is driven to enter a control mode of a gearbox control unit, wherein the gear shifting condition is that the speed of the whole vehicle does not exceed the maximum speed V of the whole vehicle_maxAnd the rotating speed of the driving motor reaches the gear shifting rotating speed n_N；

S3, the gearbox controller firstly controls the driving motor controller to zero and then controls the gear shifting motor to disengage, wherein the judgment condition of the driving motor torque zero clearing is that the driving motor torque is smaller than a third set threshold value T_c；

S4, firstly, the gearbox controller sends the target rotating speed of the driving motor to the driving motor controller, then the driving motor controller adjusts the speed of the driving motor according to the target rotating speed of the driving motor until the differential speed between the adjusted rotating speed of the driving motor and the target rotating speed of the driving motor is qualified, wherein the judging condition of the qualified differential speed is that the difference value between the adjusted rotating speed of the driving motor and the target rotating speed of the driving motor is smaller than a fourth set threshold value n_c；

S5, the gearbox controller firstly controls the gear shifting motor to engage in a gear, then carries out secondary road condition judgment, secondly compares the judgment result of the secondary road condition with the judgment result of the primary road condition, if the judgment result of the secondary road condition is the same as the judgment result of the primary road condition, takes the judgment result of the primary road condition as the actual road condition, and if the judgment result of the secondary road condition is different from the judgment result of the primary road condition, takes the road condition of a flat road as the actual road condition, establishes a target torque calculation function according to the speed and the transmission ratio of the whole vehicle, and finally calculates through the target;

wherein, the second road condition judgment specifically comprises: the speed changing box controller obtains the wheel speed change rate through the whole vehicle wheel speed calculation obtained through the wheel speed sensor signal, if the wheel speed change rate is a negative value and the absolute value of the wheel speed change rate is larger than a first set threshold value K₁Judging that the current road condition is an uphill road condition, and if the wheel speed change rate is a positive value and the absolute value of the wheel speed change rate is greater than a second set threshold value K₂Judging the current road condition as a downhill road condition, otherwise judging the current road condition as a level road condition;

the target torque calculation function is:

T＝P_e*9550*X/n

in the above formula, T is the target torque, P_eFor the power of the drive motor, X is a weighting coefficient, n is the rotational speed of the drive motor, η_TFor transmission system efficiency, G is the overall vehicle gravity, f is the rolling resistance coefficient, u_aAs the speed of the vehicle, C_DIs an air resistance coefficient, A is a windward area, i is a road gradient, delta is a mass conversion coefficient, m is the vehicle mass,the X is obtained by substituting the road gradient and the actual road condition into a pre-calibrated actual road condition-road gradient-weighting coefficient MAP;

s6, the gearbox controller firstly controls the driving motor controller to adjust the torque of the driving motor to a target torque, and then sends a gear shifting completion signal to the vehicle control unit;

and S7, the driving motor controller enters a control mode of the whole vehicle controller.