A method, device and vehicle for preventing vehicles from rolling back.

Abstract

This invention relates to the field of new energy vehicles, specifically to a vehicle anti-rollback control method, device, and vehicle. It includes the following steps: When the vehicle is in a parking position, if the vehicle meets the torque compensation conditions, the base torque and rolling resistance weighted torque are added to obtain the target compensation torque for the motor, and torque adjustment control is performed. The rolling resistance weighted torque is updated as follows: an initial value of the rolling resistance weighted torque is set and stored; the torque T_g1 of the motor controlled by torque control is obtained; when the motor speed remains at zero, the time difference t_diff is calculated, and the current motor torque T_g2 is obtained. When the time difference is greater than the preset time difference t_diff1, the rolling resistance weighted torque is: (t_diff-t_diff1) / t_diff1*(T_g2-T_g1). If the absolute value of the difference between the calculated rolling resistance weighted torque and the stored rolling resistance weighted torque is greater than or equal to a preset threshold for the difference in rolling resistance weighted torque, then it is updated; otherwise, it is not updated. If the current vehicle meets the speed control conditions, speed control is performed, controlling the motor speed to zero. This prevents the vehicle from rolling backward and ensures vehicle safety.

Description

Technical Field

[0001] This invention relates to a method, device, and vehicle for preventing vehicle rollback, belonging to the field of new energy vehicle technology. Background Technology

[0002] New energy vehicles have become the current trend in automotive development, especially in the commercial vehicle sector where electric vehicles are widely used. During vehicle operation, starting on an incline requires the driver to frequently switch between the brake and accelerator pedals, which can easily lead to driver fatigue and makes it impossible to prevent the vehicle from rolling backward. This is particularly true in the commercial vehicle sector, where the heavy loads cause significant backward rolling, thus necessitating anti-rollback control measures.

[0003] Currently, most anti-rollback control methods in the new energy industry use zero-speed motor control or PID torque adjustment based on speed difference by the vehicle controller. Due to motor response issues, vehicle rollback is unavoidable, especially when the vehicle is heavily loaded, which poses a significant safety hazard. Summary of the Invention

[0004] The purpose of this invention is to provide a vehicle anti-rollover control method, device, and vehicle to solve the problem of vehicles rolling backward due to slow motor response in the prior art.

[0005] To achieve the above objectives, the present invention includes:

[0006] This invention provides a method for preventing vehicles from rolling back, comprising the following steps:

[0007] 1) When the vehicle is in a parking position, if the vehicle meets the torque compensation condition, the base torque and rolling resistance weighted torque are added together to obtain the target compensation torque for the motor, and torque control is performed. The rolling resistance weighted torque is updated as follows: an initial value of the rolling resistance weighted torque is set and stored; the motor torque T_g1 when the motor switches from torque control to speed control is obtained; when the motor speed is kept at zero, the time difference t_diff between when the motor speed is kept at zero and when the motor switches from torque control to speed control is calculated, and the motor torque T_g2 when the motor speed is kept at zero is obtained; when the time difference between when the motor speed is kept at zero and when the motor switches from torque control to speed control is greater than the preset time difference t_diff1, the rolling resistance weighted torque is calculated according to the following formula:

[0008] (t_diff-t_diff1) / t_diff1*(T_g2-T_g1), if the absolute value of the difference between the calculated rolling resistance weighted torque and the stored rolling resistance weighted torque is greater than or equal to the preset threshold for the difference of rolling resistance weighted torque, then the rolling resistance weighted torque is updated according to the calculated rolling resistance weighted torque; otherwise, it is not updated.

[0009] 2) After torque control is performed, if the current vehicle meets the speed control conditions, speed control is performed to control the motor to zero speed.

[0010] Beneficial effects: Before controlling the speed of the motor, this invention performs torque control first, thereby improving the time it takes for the motor to switch to zero speed. Specifically, during torque control, the target compensation torque of the motor is the sum of the base torque and the rolling resistance weighted torque, and the rolling resistance weighted torque is updated in real time. This allows the target compensation torque of the motor to change with the vehicle's changes, ensuring the effectiveness of torque compensation. Furthermore, when the speed control conditions are met, the motor achieves zero speed control, avoiding vehicle lag and ensuring vehicle safety.

[0011] Furthermore, during torque control, the target torque of the motor is gradually brought to the target compensated torque of the motor according to the set torque compensation gradient. The torque compensation gradient is calculated as the product of the base value of the torque compensation gradient and the weighted coefficient of the motor compensation torque Ramp.

[0012] Beneficial effects: The torque compensation gradient is calculated by using the base value of the torque compensation gradient and the weighted coefficient of the motor compensation torque Ramp, thereby gradually stabilizing the motor target torque to reach the motor target compensation torque, ensuring the safe, reliable and stable operation of the vehicle.

[0013] Furthermore, the update method for the motor compensation torque Ramp weighting coefficient is as follows: set the initial value of the motor compensation torque Ramp weighting coefficient, obtain the motor speed at the beginning and the motor speed after motor torque compensation, and when the difference between the motor speed after motor torque compensation and the motor speed at the beginning is greater than or equal to the preset threshold of motor speed, the new motor compensation torque Ramp weighting coefficient = the current motor compensation torque Ramp weighting coefficient * (1 + motor speed difference / preset threshold of motor speed); otherwise, the new motor compensation torque Ramp weighting coefficient = the current motor compensation torque Ramp weighting coefficient * (1 - motor speed difference / preset threshold of motor speed).

[0014] Beneficial effects: The motor compensation torque Ramp weighting coefficient is updated and changed in real time according to the actual situation of the vehicle's current motor speed, which is consistent with the actual situation of the vehicle, and achieves effective compensation for motor torque.

[0015] Furthermore, the torque compensation conditions include: the brake pedal opening is less than or equal to the second brake pedal opening preset threshold, the handbrake is in the released state, and the accelerator pedal opening is less than the accelerator pedal opening preset threshold.

[0016] Beneficial effects: By comprehensively considering both the brake pedal opening and the accelerator pedal opening, torque compensation judgment can be made more accurately, allowing for a more accurate determination of whether torque compensation should be performed.

[0017] Furthermore, when the vehicle passes the self-check, if the current slope is greater than or equal to the preset slope threshold, the vehicle is not in neutral, the handbrake or brake pedal opening is greater than the first preset brake pedal opening threshold, the motor speed is less than or equal to the first preset speed threshold, the accelerator pedal opening is less than or equal to the preset accelerator pedal opening threshold, and the motor rotation direction meets the preset direction, then the vehicle is determined to be in a parking state.

[0018] Beneficial effects: By comprehensively considering multiple conditions such as current slope, vehicle gear status, handbrake status or brake pedal opening, motor speed, accelerator pedal opening, and motor rotation direction, the assessment of whether the vehicle is in a parking position is more comprehensive and accurate.

[0019] Furthermore, the speed control conditions include: the absolute value of the difference between the actual torque of the motor and the compensated torque of the motor is within the set range, or the brake pedal opening is less than or equal to the second brake pedal opening preset threshold, or the motor rotation direction is opposite to the preset direction and the difference between the motor speed and the target speed is greater than or equal to the second speed preset threshold.

[0020] Beneficial effects: By comprehensively considering multiple factors such as the vehicle motor rotation direction, motor speed, actual motor torque, and brake pedal opening information, a more comprehensive judgment is made on whether the vehicle speed control is required, ensuring the vehicle does not roll backward and thus ensuring vehicle safety.

[0021] Furthermore, the base torque is determined by the slope, vehicle weight, and the relationship between the slope vehicle weight and the base torque.

[0022] Beneficial effects: Based on the relationship between slope, vehicle weight, and slope weight and base torque, this method solves the problem of different base torque requirements caused by different vehicle loads and slope conditions, ensuring a more accurate base torque.

[0023] Furthermore, when the vehicle is in a parking position, the brake pedal opening is zero and the handbrake is released, the vehicle enters speed control to control the motor to zero speed.

[0024] Beneficial effect: When the vehicle is in a parking position, considering the brake pedal opening and handbrake status, if the brake pedal opening is zero and the handbrake is released, there is no need to adjust the torque; the anti-rollover control can be completed directly by adjusting the speed.

[0025] The present invention also provides a vehicle anti-rollover control device, including a processor and a memory, wherein the processor is used to execute computer program instructions stored in the memory to implement the above-described vehicle anti-rollover control method and achieve the same beneficial effects as the method.

[0026] The present invention also provides a vehicle that includes the vehicle anti-rollover control device described above and achieves the same beneficial effects as the device. Attached Figure Description

[0027] Figure 1 This is a flowchart of the vehicle anti-rollover control method of the present invention. Detailed Implementation

[0028] The concept of this invention is as follows: when the vehicle meets the parking slope condition and the torque compensation condition, the motor compensation torque is calculated based on the base torque and the rolling resistance weighted torque, and the rolling resistance weighted torque is continuously updated. According to the set torque compensation gradient, the motor target torque is gradually brought to the motor target compensation torque to complete the torque compensation. When the vehicle meets the speed control condition, speed control is performed to control the motor to zero speed, which improves the zero speed control time when switching to speed control, avoids the vehicle rolling backward, and ensures the safety of the vehicle.

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0030] Method Implementation Examples:

[0031] The vehicle anti-rollover control method in this embodiment of the method is as follows: Figure 1 As shown, it includes the following steps:

[0032] Step 1: Determine if the vehicle meets the requirements for parking on a slope.

[0033] 1) Initialization: The vehicle controller determines that the vehicle is powered on based on the key switch signal and checks the communication status between the vehicle controller and the motor controller. If the communication is abnormal, the self-test will fail and the vehicle will be prohibited from entering the anti-slip state.

[0034] 2) If the self-test passes and the vehicle controller obtains the current slope from the slope sensor as greater than or equal to the set threshold p1, the vehicle is in non-neutral gear, the handbrake or brake pedal opening exceeds the set threshold U1, the motor speed is less than or equal to the set speed threshold n1, the motor rotation direction is the same as the desired rotation direction, and the accelerator pedal opening is less than or equal to the set threshold A1, it is determined that the vehicle is currently in a parking state. At this time, the motor compensation torque needs to be calculated in advance.

[0035] Step 2: If the vehicle meets the parking slope conditions, then determine whether the vehicle meets the torque compensation conditions.

[0036] When the vehicle is in a parking position and the brake pedal opening is less than or equal to the set threshold U2, the handbrake is released, and the accelerator pedal opening is less than the set threshold A1, that is, the vehicle is in a parking position and the brake is released, it enters the torque compensation stage, at which time the output motor compensates the torque.

[0037] If the vehicle is on a slope, the brake pedal is open to zero and the handbrake is released, then there is no need for torque compensation, and the vehicle will directly enter speed control mode.

[0038] Step 3: If the vehicle meets the torque compensation conditions, calculate the motor compensation torque and adjust and control the motor torque.

[0039] When the vehicle is in a parking position, the motor torque compensation calculation is performed based on the slope information, vehicle weight information, vehicle rolling resistance coefficient, and rolling resistance weighted torque. After entering the anti-rollover state, the motor compensation torque T is output according to the change in brake pedal opening. The compensation torque is obtained by looking up a two-dimensional table based on the slope and vehicle weight, which is the base torque T1 plus the rolling resistance weighted torque T2. The base torque lookup table needs to be strictly calibrated.

[0040] When calculating the compensation torque, it is necessary to calculate the rolling resistance weighted torque. The rolling resistance weighted torque mainly takes into account that as the vehicle is used, its condition will change from its factory condition. In particular, tire wear or tire replacement will cause a significant change in tire rolling resistance, which will affect the anti-rollover effect.

[0041] The update process for the rolling resistance weighted torque is as follows:

[0042] 1. Set the initial value of rolling resistance weighted torque to 0.

[0043] 2. After power-on, read the stored rolling resistance weighted torque and use it in the current cycle.

[0044] 3. During the speed control phase, the motor switches from torque control to speed control and starts timing. Simultaneously, the current motor torque value T_g1 is recorded. After the motor maintains 0 speed control, the time difference t_diff is calculated, and the current motor torque value T_g2 is recorded. If the time difference t_diff is greater than or equal to the preset time difference t_diff1, then the rolling resistance weighted torque = (t_diff - t_diff1) / t_diff1 * (T_g2 - T_g1).

[0045] 4. Rolling resistance weighted torque update rule: If the absolute value of the difference between the calculated rolling resistance weighted torque and the stored rolling resistance weighted torque is greater than or equal to T_mean, then update; otherwise, do not update.

[0046] 5. The rolling resistance weighted torque needs to be stored after power-off and read and used the next time power is turned on.

[0047] During the torque compensation phase, the torque compensation calculation module sends the target torque to the motor controller. The target torque rise gradient Ramp is obtained by looking up the base value based on the gradient and vehicle weight, and then combining it with the motor compensation torque Ramp weighting coefficient to obtain the final torque compensation rise gradient. The final torque compensation rise gradient = the base value of the torque compensation rise gradient * the motor compensation torque Ramp weighting coefficient.

[0048] The steps for updating the weighted coefficient of the motor compensation torque Ramp are as follows:

[0049] 1. Set the initial value of the motor torque compensation variation coefficient: 1.

[0050] 2. After power-on, read the stored motor torque compensation variation coefficient and use it in a loop.

[0051] 3. When the handbrake is released and the vehicle enters the anti-slip slope, the motor torque compensation change coefficient will not be updated.

[0052] 4. Upon releasing the brake and entering the anti-slip slope, the motor torque compensation variation coefficient needs to be updated based on the motor speed difference. At the start of motor torque compensation (t1), the current motor speed value n_t1 is recorded. After motor torque compensation ends, the difference n_diff between the current motor speed value n_t2 and n_t1 determines whether an update is needed. If n_diff is greater than or equal to the set threshold n_3, it is considered that the motor torque rise gradient needs to be increased during torque compensation, and the new motor torque compensation variation coefficient = current motor torque compensation variation coefficient * (1 + n_diff / n_3). If n_diff is less than or equal to the set threshold - (n_3), then the current motor torque compensation variation coefficient * (1 - n_diff / n_3), where the sign needs to be adjusted based on the motor rotation direction. This value needs to be stored after power-off and retrieved upon the next power-on.

[0053] Step 4: After torque compensation of the motor, determine whether the speed control conditions are met. If they are met, control the motor to zero speed.

[0054] If the absolute value of the difference between the actual torque and the compensated torque of the motor is within the set range (hysteresis, upper limit T_max, lower limit T_min), or the brake pedal opening is less than or equal to the set threshold U2 (U2 must be less than U1), or the motor rotation direction is opposite to the set rotation direction and the difference between the motor speed and the desired speed is greater than or equal to the set threshold n2, the motor enters the speed control stage and controls the motor speed to 0 for anti-slip control.

[0055] This method adjusts the vehicle's torque through motor torque compensation when the vehicle is in a parking position and meets the torque compensation conditions. When the vehicle meets the speed control conditions, speed control is implemented, keeping the motor at zero speed. Pre-setting the compensation torque reduces the adjustment time for switching to zero-speed motor control. This prevents the vehicle from rolling backward and ensures vehicle safety.

[0056] Device Example:

[0057] This invention discloses a vehicle anti-rollover control device, comprising a memory, a processor, and an internal bus. The processor and memory communicate and exchange data via the internal bus. The processor can be a microprocessor (MCU), a programmable logic device (FPGA), or other processing device; the memory can be various types of memory that store information electrically, such as RAM or ROM. The processor executes program instructions stored in the memory to implement the vehicle anti-rollover control method described in the method embodiments of this invention. This method has been described in detail in the method embodiments and will not be repeated here.

[0058] Vehicle Example:

[0059] The vehicle in this embodiment includes a vehicle anti-rollover control device described in the system embodiment. The vehicle using the vehicle anti-rollover control device of the present invention can better achieve anti-rollover control, avoid vehicle rollover caused by motor response problems, and ensure vehicle safety. The device has been described in detail in the above embodiments and will not be repeated here.

Claims

1. A method for preventing vehicles from rolling back on slopes, characterized in that, Includes the following steps: 1) When the vehicle is in a parking position, if the vehicle meets the torque compensation condition, the base torque and rolling resistance weighted torque are added together to obtain the target compensation torque for the motor, and torque control is performed. The rolling resistance weighted torque is updated as follows: an initial value of the rolling resistance weighted torque is set and stored; the motor torque T_g1 when the motor switches from torque control to speed control is obtained; when the motor speed remains zero, the time difference t_diff between when the motor speed remains zero and when the motor switches from torque control to speed control is calculated, and the time difference t_diff between when the motor speed remains zero and when the motor switches from torque control to speed control is obtained. Motor torque T_g2, when the time difference between the motor speed being zero and the motor switching from torque control to speed control is greater than the preset time difference t_diff1, the rolling resistance weighted torque is calculated according to the following formula: (t_diff-t_diff1) / t_diff1*(T_g2-T_g1). If the absolute value of the difference between the calculated rolling resistance weighted torque and the stored rolling resistance weighted torque is greater than or equal to the preset threshold for the difference of rolling resistance weighted torque, then the rolling resistance weighted torque is updated according to the calculated rolling resistance weighted torque; otherwise, it is not updated. 2) After torque control is performed, if the current vehicle meets the speed control conditions, speed control is performed to control the motor to zero speed.

2. The vehicle anti-rollover control method according to claim 1, characterized in that, When performing torque control, the target torque of the motor is gradually brought to the target compensation torque of the motor according to the set torque compensation gradient. The torque compensation gradient is calculated as the product of the base value of the torque compensation gradient and the weighting coefficient of the motor compensation torque Ramp.

3. The vehicle anti-rollover control method according to claim 2, characterized in that, The update method of the motor compensation torque Ramp weighting coefficient is as follows: set the initial value of the motor compensation torque Ramp weighting coefficient, obtain the motor speed at the beginning and the motor speed after motor torque compensation, and when the difference between the motor speed after motor torque compensation and the motor speed at the beginning is greater than or equal to the preset threshold of motor speed, the new motor compensation torque Ramp weighting coefficient = the current motor compensation torque Ramp weighting coefficient * (1 + motor speed difference / preset threshold of motor speed). Otherwise, the new motor compensation torque Ramp weighting factor = the current motor compensation torque Ramp weighting factor * (1 - motor speed difference / motor speed preset threshold).

4. The vehicle anti-rollover control method according to claim 1, characterized in that, The torque compensation conditions include: the brake pedal opening is less than or equal to the second brake pedal opening preset threshold, the handbrake is in the released state, and the accelerator pedal opening is less than the accelerator pedal opening preset threshold.

5. The vehicle anti-rollover control method according to claim 1, characterized in that, When the vehicle passes the self-check, if the current slope is greater than or equal to the preset slope threshold, the vehicle is not in neutral, the handbrake or brake pedal opening is greater than the first preset brake pedal opening threshold, the motor speed is less than or equal to the first preset speed threshold, the accelerator pedal opening is less than or equal to the preset accelerator pedal opening threshold, and the motor rotation direction meets the preset direction, then the vehicle is determined to be in a parking state.

6. The vehicle anti-rollover control method according to claim 1, characterized in that, The speed control conditions include: the absolute value of the difference between the actual torque of the motor and the compensated torque of the motor is within the set range, or the brake pedal opening is less than or equal to the second brake pedal opening preset threshold, or the motor rotation direction is opposite to the preset direction and the difference between the motor speed and the target speed is greater than or equal to the second speed preset threshold.

7. The vehicle anti-rollover control method according to claim 1, characterized in that, The base torque is determined by the slope, vehicle weight, and the relationship between the slope vehicle weight and the base torque.

8. The vehicle anti-rollover control method according to claim 1, characterized in that, When the vehicle is on a slope, the brake pedal is open to zero and the handbrake is released, the vehicle enters speed control to control the motor to zero speed.

9. A vehicle anti-rollover control device, characterized in that, It includes a processor and a memory, the processor being configured to execute computer program instructions stored in the memory to implement the vehicle anti-slip control method as described in any one of claims 1 to 8.

10. A vehicle, characterized in that, Includes the vehicle anti-rollover control device as described in claim 9.

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