An auxiliary control method, system and vehicle for preventing electric vehicle rolling

Abstract

This invention discloses an auxiliary control method, system, and vehicle for preventing electric vehicles from rolling backwards on slopes. When anti-rollback function I is activated, if the absolute value of the slope is less than or equal to S1, a first torque T1 is determined, and the control motor is requested to smoothly output the first torque T1; otherwise, the electronic parking brake system is requested to remain engaged. When anti-rollback function II is activated, if the brake pedal is pressed to activate the hill start assist function and then released, a second torque T2 is determined, and the control motor is requested to continuously and smoothly output the second torque T2 within t0; if the brake pedal is pressed but the hill start assist function is not activated, a third torque T3 is determined, and the control motor is requested to smoothly output the third torque T3. The anti-rollback function is deactivated when the deactivation conditions are met. This increases the reliability of the anti-rollback function, improves driver comfort and safety on slopes, and enhances the hill start experience for different driving styles.

Description

Technical Field

[0001] This invention belongs to the field of electric vehicle control, specifically relating to an auxiliary control method, system, and vehicle for preventing electric vehicles from rolling backwards. Background Technology

[0002] Electric vehicles are gaining popularity, but if drivers are not skilled at operating them, there is a risk of the vehicle rolling backward when starting on an incline. Even if a vehicle has a hill start assist system (HHC) and is equipped with hill start assist, the time that the hill start assist function is effective on an incline (i.e., the hill start assist function duration) is only 1 to 3 seconds. Under certain conditions or scenarios, if the driver does not press the accelerator in time after 3 seconds, the vehicle may roll backward.

[0003] CN106926751A discloses a control method and device for preventing vehicle rollback on slopes. It determines whether to enter an anti-rollback mode based on the vehicle's gear position and motor speed. When the vehicle is in anti-rollback mode, it controls the vehicle torque based on the motor speed and the target motor speed. However, this control method is simplistic, resulting in poor driver comfort on slopes and a poor experience when starting on a slope.

[0004] CN111231693A discloses an anti-rollover control method and device, which determines whether to activate the anti-rollover function based on at least one of handbrake information, brake information, motor speed information, gear information, and throttle information. If it is determined that the vehicle is in the anti-rollover function enabled state, it further determines whether the temperature of the IGBT chip exceeds the alarm temperature. When the alarm temperature is exceeded, the chip power is controlled and the maximum torque in the subsequent anti-rollover process is limited. The motor controller is used to control the vehicle to a zero-speed mode in order to suppress the vehicle's rollover. However, its control method is simplistic, resulting in poor driver comfort on slopes and a poor experience when starting on a slope.

[0005] CN113246748A discloses a method, system, and vehicle for preventing rollback in electric vehicles. When the vehicle's anti-rollback function is activated, it first performs a first-order filter on the motor speed to obtain a speed n2. Based on the first speed n2, it consults a table showing the relationship between the initial anti-rollback torque and the first speed n2 to obtain an initial anti-rollback torque Tq1. Based on the speed difference n3 between speed n2 and the target speed, it performs PI control to obtain a PI adjustment torque Tq2, where the target speed is 0 rpm. The initial anti-rollback torque Tq1 is added to the PI adjustment torque Tq2 to obtain the basic anti-rollback torque Tq3. The target anti-rollback torque Tq3 is then subjected to first-order filtering and rate-of-change processing to obtain the final anti-rollback torque. However, this control method is simplistic, resulting in poor driver comfort on inclines and a poor experience when starting on an incline.

[0006] CN112265544A discloses a hill-rollback prevention auxiliary control method for new energy vehicles. It describes how, when the hill-rollback prevention system identifies a starting hill-rollback condition, it controls the motor to output stall torque to prevent rolling back, aiming to reduce the motor speed to 0. When the hill-rollback prevention system identifies a timeout in the motor anti-rollback mechanism or a fault in the electric drive system that prevents the maintenance of stall torque, and the vehicle has not started, applied the brakes, or engaged the handbrake, the system controls the brake actuator to output driving braking force to prevent rolling back. When the hill-rollback prevention system identifies a timeout in the vehicle stability controller and the vehicle has still not applied the brakes or engaged the handbrake, the system controls the electronic parking controller to perform hill-hold control, and the electronic parking controller controls the brake actuator to continue outputting mechanical braking force for parking. When the driver starts the vehicle, applies the brakes, or engages the handbrake during the hill-rollback prevention auxiliary control process, the system automatically releases the motor stall torque or mechanical braking force. It considers introducing ESP to control the vehicle to park briefly when the motor torque stall timeout occurs, and introducing EPB to park when the ESP control timeout occurs; however, it does not provide corresponding control when there is already a rollback, which makes driving on the slope uncomfortable and the experience of starting on the slope poor. Summary of the Invention

[0007] The purpose of this invention is to provide an auxiliary control method, system, and vehicle for preventing electric vehicles from rolling backwards on slopes, so as to increase the reliability of the anti-rollback function and improve the driver's experience of starting on a slope.

[0008] The auxiliary control method for preventing electric vehicles from rolling backwards as described in this invention includes:

[0009] When the anti-rollback function I is activated, if the absolute value of the slope is less than or equal to the first preset slope S1, a first torque T1 is determined, and the control motor is requested to smoothly output the first torque T1 to prevent rollback. If the absolute value of the slope is greater than the first preset slope S1, the electronic parking brake system (EPB) is requested to maintain clamping to prevent the vehicle from rolling back. After activating the anti-rollback function I, the control methods of motor output torque anti-rollback and EPB clamping anti-rollback are adopted according to the magnitude of the absolute value of the slope. This ensures that the vehicle will not roll back, reduces the number of times the EPB is activated, and improves the service life of the EPB. In addition, it also reduces the number of times the motor outputs high torque, saving some energy consumption, ensuring a certain degree of driving smoothness, reducing the difficulty of controlling the motor to apply torque on steep slopes, and improving the driver's comfort and safety when driving on slopes.

[0010] When the anti-rollback function II is activated, if the driver presses the brake pedal to activate the hill start assist and then releases the brake pedal, a second torque T2 is determined, and the control motor is requested to continuously and smoothly output the second torque T2 for a first preset time t0 to assist the driver in starting the vehicle. If the driver presses the brake pedal but the hill start assist is not activated, a third torque T3 is determined, and the control motor is requested to smoothly output the third torque T3 to prevent the vehicle from rolling backward. The first preset time t0 is equal to the hill start assist duration. Activating the anti-rollback function II and controlling it in two ways ensures that the torque is pre-loaded during the hill start assist system (HHC) operation, preventing the motor torque from being untimely and causing the vehicle to roll backward. If the hill start assist is not activated, pressing the brake pedal loads the motor torque to assist in preventing the vehicle from rolling backward, reducing driver fatigue and improving the driver's experience when starting on a hill.

[0011] The anti-slide function will be deactivated if the conditions for deactivation are met.

[0012] Preferably, there are two methods for determining the first torque T1.

[0013] The first method involves obtaining the vehicle's mass and gradient; then, substituting the absolute values ​​of the vehicle's mass and gradient into a preset torque curve to calculate the corresponding first torque T1. The preset torque curve is a numerical fitting method used to obtain the relationship between the absolute values ​​of the vehicle's mass, gradient, and first torque, representing the relationship between the first torque and the absolute value of the vehicle's mass and gradient. The vehicle's mass is a positive value and cannot be negative; therefore, the greater the vehicle's mass, the greater the first torque. The gradient can be positive or negative; a downward-facing slope has a negative gradient, while an upward-facing slope has a positive gradient; the greater the absolute value of the gradient, the greater the first torque. Using a numerical fitting method to obtain the relationship curve between the first torque, vehicle mass, and gradient, and calculating the first torque based on this curve, reduces the number of tests and testing conditions, thus lowering development costs.

[0014] The second method involves obtaining the vehicle's mass and gradient; then, using linear interpolation, a pre-defined first torque table is consulted based on the absolute values ​​of the vehicle's mass and gradient to obtain the corresponding first torque T1. This pre-defined first torque table represents the correspondence between the absolute values ​​of the vehicle's mass and gradient and the first torque, obtained through testing. Calculating the first torque using linear interpolation reduces the number of tests and experimental conditions, thus lowering development costs.

[0015] Preferably, the method for determining the second torque T2 is as follows:

[0016] Obtain the gradient and actual vehicle speed.

[0017] Using the formula: Calculate the second torque T2.

[0018] Among them, T int This represents the torque in the first stage, and the duration of the torque in the first stage is t1, T int =k1×T crp k1 represents the correction factor, T crp T represents creep torque. comp This represents the second-stage torque, which lasts from t0 to t1. T is calculated using a PI closed-loop calculation based on the difference between the actual vehicle speed and the preset starting speed. comp The torque applied during the hill start assist function is divided into two stages, with different torques applied in the two stages (i.e., different calculation methods are used), which achieves a smooth transition between the anti-rollback function and the creep function. The PI closed-loop control in the second stage is a bottom-line control to prevent the vehicle from rolling backward.

[0019] Preferably, the duration t1 of the torque in the first stage is obtained by querying a preset time table based on the absolute value of the slope; wherein, the preset time table is a table of correspondence between the absolute value of the slope and time obtained through calibration; the larger the absolute value of the slope, the smaller the duration t1 of the torque in the first stage.

[0020] Preferably, the correction coefficient k1 is obtained by consulting a preset correction coefficient table based on the absolute value of the slope; wherein, the preset correction coefficient table is a table showing the correspondence between the absolute value of the slope and the correction coefficient obtained through calibration. The larger the absolute value of the slope, the larger the correction coefficient k1.

[0021] Preferably, the creep torque T is obtained by consulting a preset creep torque table based on the actual vehicle speed. crp The preset creep torque table is a table showing the correspondence between (actual) vehicle speed and creep torque obtained through calibration.

[0022] Preferably, requesting the motor to continuously and smoothly output the second torque T2 within the first preset time t0 means that the torque output by the motor increases from 0 according to the first gradient a to T. int And continue for t1, after which the torque from T int According to the second gradient b, change to T compAnd this continues from t0 to t1. The first gradient 'a' is obtained by looking up a preset first gradient table based on the absolute values ​​of the vehicle mass and slope. The second gradient 'b' is obtained by looking up a preset second gradient table based on the absolute values ​​of the vehicle mass and slope. The preset first gradient table is a table showing the correspondence between the first gradient obtained through calibration and the absolute values ​​of the vehicle mass and slope. The larger the vehicle mass, the larger the first gradient 'a'; the larger the absolute value of the slope, the larger the first gradient 'a'. The preset second gradient table is a table showing the correspondence between the second gradient obtained through calibration and the absolute values ​​of the vehicle mass and slope. The larger the vehicle mass, the larger the second gradient 'b'; the larger the absolute value of the slope, the larger the second gradient 'b'. By increasing the gradient, both the responsiveness and smoothness of the second torque loading are ensured, avoiding vehicle impact issues.

[0023] Preferably, requesting the motor to continuously and smoothly output the second torque T2 within the first preset time t0 means that the torque output by the motor is increased from 0 to T2 through a first-order or second-order filter. int And continue for t1, after which the torque is filtered from T by a first-order or second-order filter. int Change to T comp And it continues from t0 to t1. By using filtering, both the responsiveness of the second torque and the smoothness of its loading can be guaranteed, thus avoiding vehicle impact problems.

[0024] Preferably, the method for determining the third torque T3 is as follows:

[0025] Obtain the actual vehicle speed, gradient, and brake pedal travel.

[0026] The initial torque T is obtained by referring to the preset initial torque table based on the absolute values ​​of the actual vehicle speed and gradient. s The preset initial torque table is a table showing the correspondence between the absolute values ​​of the actual vehicle speed and gradient and the initial torque, obtained through calibration.

[0027] The correction factor k2 is obtained by consulting a preset correction factor table based on the brake pedal travel. The preset correction factor table is a table showing the correspondence between brake pedal travel and correction factors obtained through calibration. The greater the brake pedal travel, the smaller the correction factor.

[0028] Use the formula: T3=k2×T s The third torque T3 is calculated.

[0029] The third torque, T3, is determined based on the actual vehicle speed, the absolute value of the slope, and the brake pedal travel. This ensures that the driver can follow the vehicle on the slope and prevent rolling back at different speeds and slopes, reducing the difficulty of driving and improving the driver's comfort and safety on the slope, as well as enhancing the driver's experience of starting on a slope.

[0030] Preferably, requesting the motor to smoothly output the first torque T1 means that the torque output by the motor is increased from 0 to the first torque T1 according to the third gradient c. The third gradient c is obtained by looking up a preset third gradient table based on the absolute values ​​of the vehicle mass and the slope. The preset third gradient table is a table showing the correspondence between the third gradient obtained through calibration and the absolute values ​​of the vehicle mass and the slope. The greater the vehicle mass, the larger the third gradient c; the greater the absolute value of the slope, the larger the third gradient c. This gradient increase method ensures both the responsiveness and smoothness of the first torque loading, avoiding vehicle impact issues.

[0031] Preferably, requesting the smooth output of the third torque T3 by the control motor means requesting the torque output by the control motor to increase from 0 to the third torque T3 according to the fourth gradient d. The fourth gradient d is obtained by looking up a preset fourth gradient table based on the absolute values ​​of the vehicle mass and slope. The preset fourth gradient table is a table showing the correspondence between the fourth gradient obtained through calibration and the absolute values ​​of the vehicle mass and slope. The greater the vehicle mass, the larger the fourth gradient d; the greater the absolute value of the slope, the larger the fourth gradient d. This gradient increase method ensures both the responsiveness and smooth loading of the third torque, avoiding vehicle impact issues.

[0032] Preferably, requesting the motor to smoothly output the first torque T1 means that the torque output by the motor is increased from 0 to the first torque T1 through first-order or second-order filtering. This filtering method ensures both the responsiveness and smoothness of the first torque loading, preventing vehicle impact issues.

[0033] Preferably, requesting the smooth output of the third torque T3 by the control motor means that the torque output by the control motor is increased from 0 to the third torque T3 through first-order or second-order filtering. This filtering method ensures both the responsiveness and smooth loading of the third torque, avoiding any impact issues on the vehicle.

[0034] Preferably, if conditions 1a to 1e are met simultaneously, it indicates that the conditions for activating anti-slide function I are met, and anti-slide function I will be activated. Among these,

[0035] Condition 1a is: the gear is switched from P to D or R.

[0036] Condition 1b is: when switching to D gear, the slope is greater than or equal to S2; or when switching to R gear, the slope is less than or equal to -S2; where S2 represents the second preset slope, 0 < S2 < S1.

[0037] Condition 1c is: the actual vehicle speed is less than or equal to the preset first vehicle speed V1.

[0038] Condition 1d is: the accelerator pedal is not depressed.

[0039] Condition 1e is: No faults affecting motor torque.

[0040] Preferably, if conditions 2a to 2g are met simultaneously, it indicates that the conditions for activating the anti-slide function II are met, and the anti-slide function II will be activated. Among these,

[0041] Condition 2a is: the gear is D or R.

[0042] Condition 2b is: when in D gear, the slope is greater than or equal to S2; or when in R gear, the slope is less than or equal to -S2.

[0043] Condition 2c is: the actual vehicle speed is less than or equal to the preset first vehicle speed V1.

[0044] Condition 2d is: the accelerator pedal is not depressed.

[0045] Condition 2e is: the handbrake is not engaged (meaning the wheels are not clamped).

[0046] Condition 2f is: The automatic parking function (i.e., AUTOHOLD) is not activated.

[0047] Condition 2g is: no faults affecting motor torque.

[0048] Preferably, if any one of conditions 3a to 3g is met, it indicates that the anti-slide function exit condition is met; wherein,

[0049] Condition 3a is: the actual vehicle speed is greater than the preset second vehicle speed V2 and the accelerator pedal opening is greater than the preset accelerator opening A1.

[0050] Condition 3b is: the brake pedal is fully depressed and maintained for a second preset time t2.

[0051] Condition 3c is: A collision failure occurs.

[0052] Condition 3d is: handbrake engaged.

[0053] Condition 3e is: the gear is switched from D or R (i.e., drive gear) to non-drive gear (i.e., P or N gear).

[0054] Condition 3f is: (A vehicle equipped with radar or camera functions) detects that the distance to the target in front is less than the preset distance threshold B1.

[0055] Condition 3g is: (For vehicles equipped with automatic emergency braking function) the automatic emergency braking function is activated.

[0056] The auxiliary control system for preventing electric vehicles from rolling back on a slope according to the present invention includes an auxiliary controller, which is programmed to execute the above-described auxiliary control method for preventing electric vehicles from rolling back on a slope.

[0057] The vehicle described in this invention includes the aforementioned auxiliary control system for preventing electric vehicles from rolling backwards.

[0058] This invention differentiates between different driver operation modes, considering scenarios such as the vehicle being parked on a slope and the driver shifting from P to D or R; the vehicle remaining in D or R and activating the hill start assist function by pressing the brake pedal; and the vehicle remaining in D or R and activating the hill start assist function by pressing the brake pedal. Different motor torques are applied for different operation modes, increasing the reliability of the anti-rollover function, improving driver comfort and safety on slopes, and enhancing the driver's hill start experience. Attached Figure Description

[0059] Figure 1 This is a diagram of the architecture of the auxiliary control system for preventing electric vehicles from rolling backwards in Example 1.

[0060] Figure 2 This is a flowchart of the auxiliary control for preventing electric vehicles from rolling back on a slope in Example 1. Detailed Implementation

[0061] Example 1: As Figure 1 As shown, the auxiliary control system for preventing electric vehicle rollover in this embodiment includes an auxiliary controller 1. The auxiliary controller 1 is connected to the motor controller 2, acquires fault information affecting motor torque, and sends a signal requesting control of the motor to output the relevant torque to the motor controller 2. Upon receiving the signal, the motor controller 2 controls the motor 4 to output the relevant torque. The auxiliary controller 1 is also connected to the electronic parking brake system 3 (EPB), acquires handbrake status information, and sends a signal requesting the electronic parking brake system to maintain clamping to the electronic parking brake system 3. The auxiliary controller 1 acquires vehicle mass, gradient (i.e., the gradient of the road where the vehicle is located), accelerator pedal opening, actual vehicle speed, gear information, brake pedal travel, collision fault information, automatic parking function activation flag (used to determine whether the automatic parking function is activated), distance information between the vehicle and the target (object or vehicle) ahead, and automatic emergency braking function activation flag (used to determine whether the automatic emergency braking function is activated) from the CAN bus.

[0062] like Figure 2 As shown, the auxiliary control method for preventing electric vehicles from rolling back on a slope in this embodiment adopts the aforementioned auxiliary control system for preventing electric vehicles from rolling back on a slope. The auxiliary control method specifically includes the following steps:

[0063] Step 1: Determine if the conditions for activating the anti-slide function I are met. If yes, proceed to Step 2; otherwise, proceed to Step 6.

[0064] If conditions 1a to 1e are met simultaneously, it indicates that the conditions for activating the anti-rollback function I are met. Condition 1a is: the gear is switched from P to D or R. Condition 1b is: when switching to D, the gradient is greater than or equal to 5%, or when switching to R, the gradient is less than or equal to -5%. In this embodiment, S2 = 5%. Condition 1c is: the actual vehicle speed is less than or equal to the preset first vehicle speed V1; in this embodiment, V1 = 1.0 km / h. Condition 1d is: the accelerator pedal is not depressed (i.e., the accelerator pedal opening is less than 1%). Condition 1e is: there is no fault affecting the motor torque.

[0065] Step 2: Activate the anti-slide function I, and then proceed to Step 3.

[0066] Step 3: Determine whether the absolute value of the slope is less than or equal to the first preset slope S1 (S1 = 10% in this embodiment). If yes, proceed to step 4; otherwise, proceed to step 5.

[0067] Step 4: Determine the first torque T1, and request the motor controller 2 to control the motor 4 to smoothly output the first torque T1, and then execute step 12.

[0068] After receiving the request signal to control the motor to smoothly output the first torque T1, the motor controller 2 controls the motor 4 to smoothly output the first torque T1 to prevent slippage.

[0069] The method for determining the first torque T1 is as follows: First, obtain the vehicle mass and the slope (i.e., the slope of the road where the vehicle is located); then, substitute the absolute values ​​of the vehicle mass and the slope into a preset torque curve to calculate the corresponding first torque T1. The preset torque curve is a curve showing the correspondence between the absolute value of the first torque, the vehicle mass, and the slope, obtained by using a numerical fitting method (such as the least squares method) based on the test data of the vehicle mass, the absolute value of the slope, and the first torque (e.g., Table 1).

[0070] Table 1

[0071] The absolute value of the slope is 1. The absolute value of the slope 2 The absolute value of the slope is 3. The absolute value of the slope is 4. Vehicle weight 1 T11 T12 T13 T14 Vehicle weight 2 T21 T22 T23 T24 Vehicle weight 3 T31 T32 T33 T34 Vehicle weight 4 T41 T42 T43 T44

[0072] The vehicle's mass is a positive value and cannot be negative; therefore, the greater the vehicle's mass, the greater the initial torque. The gradient can be positive or negative; downhill, the gradient is negative, and uphill, it is positive. The greater the absolute value of the gradient, the greater the initial torque. By using a numerical fitting method to obtain the curve showing the relationship between the initial torque, vehicle mass, and the absolute value of the gradient, and calculating the initial torque based on this curve, some experimental and testing conditions can be reduced, thus lowering R&D costs.

[0073] Requesting motor controller 2 to smoothly output the first torque T1 means requesting motor controller 2 to increase the output torque of the motor from 0 to the first torque T1 according to the third gradient c. The third gradient c is obtained by looking up a preset third gradient table based on the absolute values ​​of the vehicle mass and slope. The preset third gradient table is a table showing the correspondence between the third gradient obtained through calibration and the absolute values ​​of the vehicle mass and slope. The larger the vehicle mass, the larger the third gradient c; the larger the absolute value of the slope, the larger the third gradient c. This gradient increase method ensures both the responsiveness and smoothness of the first torque loading, avoiding vehicle impact issues.

[0074] Step 5: Request the electronic parking brake system (EPB) to remain clamped to prevent the vehicle from rolling backwards, and then proceed to step 12.

[0075] After activating the anti-rollback function I, the control methods of motor output torque anti-rollback and EPB clamping anti-rollback are adopted according to the absolute value of the slope. This can ensure that the vehicle will not roll backward (the backward rollback distance is less than 1cm), reduce the number of EPB operations, and improve the service life of EPB. In addition, it can also reduce the number of times the motor outputs high torque, save some energy consumption, ensure a certain degree of driving smoothness, and reduce the difficulty of controlling the motor to apply torque on steep slopes.

[0076] Step 6: Determine if the conditions for activating the anti-slide function II are met. If yes, proceed to step 7; otherwise, end the process.

[0077] If conditions 2a to 2g are met simultaneously, the conditions for activating the anti-rollback function II are met. Condition 2a is: the gear is in D or R. Condition 2b is: when in D gear, the slope is greater than or equal to 5%; or when in R gear, the slope is less than or equal to -5%. Condition 2c is: the actual vehicle speed is less than or equal to the preset first vehicle speed V1. Condition 2d is: the accelerator pedal is not depressed. Condition 2e is: the handbrake is not engaged (meaning the wheels are not clamped). Condition 2f is: the automatic parking function (AUTOHOLD) is not activated. Condition 2g is: there is no fault affecting the motor torque.

[0078] Step 7: Activate the anti-slide function II, and then proceed to step 8.

[0079] Step 8: Determine if the brake pedal is pressed to activate the hill start assist function. If yes, proceed to step 9; otherwise, proceed to step 11.

[0080] Step 9: Determine whether the brake pedal has been released. If yes, proceed to Step 10; otherwise, proceed to Step 12.

[0081] Step 10: Determine the second torque T2, and request the motor controller 2 to control the motor to continuously and smoothly output the second torque T2 within the first preset time t0, and then execute step 12. Wherein, the first preset time t0 is equal to the hill start assist function hold time.

[0082] After receiving a request signal to control the motor to continuously and smoothly output the second torque T2 within a first preset time t0, the motor controller 2 controls the motor 4 to continuously and smoothly output the second torque T2 within the first preset time t0, assisting the driver in pressing the accelerator to start.

[0083] The method for determining the second torque T2 is as follows:

[0084] Obtain the gradient (i.e., the gradient of the road where the vehicle is located) and the actual vehicle speed.

[0085] Using the formula: Calculate the second torque T2.

[0086] Among them, T int This represents the torque in the first stage, and the duration of the torque in the first stage is t1, T int =k1×T crp k1 represents the correction factor, T crp T represents creep torque. comp This represents the second-stage torque, which lasts from t0 to t1. T is calculated using a PI closed-loop calculation based on the difference between the actual vehicle speed and the preset starting speed. comp In this embodiment, the preset starting speed is 2.0 km / h. The P parameter in the PI closed-loop calculation is obtained by looking up the preset P parameter table based on the difference between the actual vehicle speed and the preset starting speed. Similarly, the I parameter in the PI closed-loop calculation is obtained by looking up the preset I parameter table based on the difference between the actual vehicle speed and the preset starting speed. The preset P parameter table is a table showing the correspondence between the difference between the actual vehicle speed and the starting speed, obtained through calibration, and the P parameter. The smaller the difference between the actual vehicle speed and the starting speed, the smaller the P parameter. Likewise, the preset I parameter table is a table showing the correspondence between the difference between the actual vehicle speed and the starting speed, obtained through calibration, and the I parameter. The smaller the difference between the actual vehicle speed and the starting speed, the smaller the I parameter.

[0087] The duration t1 of the first stage torque is obtained by querying the preset time table based on the absolute value of the slope; where the preset time table is a table of correspondence between the absolute value of the slope and time obtained through calibration; the larger the absolute value of the slope, the smaller the duration t1 of the first stage torque.

[0088] The correction coefficient k1 is obtained by looking up the preset correction coefficient table based on the absolute value of the slope. The preset correction coefficient table is a table showing the correspondence between the absolute value of the slope and the correction coefficient obtained through calibration. The larger the absolute value of the slope, the larger the correction coefficient k1.

[0089] The creep torque T is obtained by consulting the preset creep torque table based on the actual vehicle speed. crp The preset creep torque table is a table showing the correspondence between vehicle speed and creep torque obtained through calibration.

[0090] The request for motor controller 2 to control the motor to continuously and smoothly output the second torque T2 within the first preset time t0 means: the request for motor controller 2 to control the motor output torque to increase from 0 according to the first gradient a to T. int And continue for t1, after which the torque from T int According to the second gradient b, change to T comp The process continues from t0 to t1. The first gradient 'a' is obtained by looking up the absolute values ​​of the vehicle mass and slope in a preset first gradient table, and the second gradient 'b' is obtained by looking up the absolute values ​​of the vehicle mass and slope in a preset second gradient table. The preset first gradient table is a table showing the correspondence between the first gradient obtained through calibration and the absolute values ​​of the vehicle mass and slope. The larger the vehicle mass, the larger the first gradient 'a'; the larger the absolute value of the slope, the larger the first gradient 'a'. Similarly, the preset second gradient table is a table showing the correspondence between the second gradient obtained through calibration and the absolute values ​​of the vehicle mass and slope. The larger the vehicle mass, the larger the second gradient 'b'; the larger the absolute value of the slope, the larger the second gradient 'b'. This gradient increase method ensures both the responsiveness and smoothness of the second torque loading, preventing vehicle impact issues.

[0091] The torque applied during the operation of the ramp assist function is divided into two stages, with different torques applied in the two stages (i.e., different calculation methods are used). This allows for a smooth transition between the anti-rollback function and the creep function. The PI closed-loop control in the second stage is a safety control to prevent the vehicle from rolling backward.

[0092] Step 11: Determine the third torque T3, and request motor controller 2 to control the motor to smoothly output the third torque T3, and then execute step 12.

[0093] After receiving the request signal to control the motor to smoothly output the third torque T3, the motor controller 2 controls the motor 4 to smoothly output the third torque T3 to prevent slippage.

[0094] The method for determining the third torque T3 is as follows:

[0095] Obtain the actual vehicle speed, gradient (i.e., the gradient of the road where the vehicle is located), and brake pedal travel.

[0096] The initial torque T is obtained by consulting the preset initial torque table based on the actual vehicle speed and the absolute value of the slope. s The preset initial torque table is a table showing the correspondence between the absolute values ​​of the actual vehicle speed and gradient and the initial torque, obtained through calibration.

[0097] The correction factor k2 is obtained by querying the preset correction factor table based on the brake pedal travel. The preset correction factor table is a table showing the correspondence between the brake pedal travel and the correction factor obtained through calibration. The larger the brake pedal travel, the smaller the correction factor.

[0098] Use the formula: T3=k2×T s The third torque T3 is calculated.

[0099] The third torque, T3, is determined based on the actual vehicle speed, the absolute value of the slope, and the brake pedal travel. It can ensure that the driver's intention to follow the vehicle on the slope and the anti-roll-off function can be realized at different vehicle speeds and slopes, reducing the difficulty of driving.

[0100] Requesting motor controller 2 to smoothly output the third torque T3 means requesting motor controller 2 to increase the output torque of the motor from 0 to the third torque T3 according to the fourth gradient d. The fourth gradient d is obtained by looking up a preset fourth gradient table based on the absolute values ​​of the vehicle mass and slope. The preset fourth gradient table is a table showing the correspondence between the fourth gradient and the absolute values ​​of the vehicle mass and slope obtained through calibration. The greater the vehicle mass, the larger the fourth gradient d; the greater the absolute value of the slope, the larger the fourth gradient d. This gradient increase method ensures both the responsiveness and smoothness of the third torque loading, avoiding vehicle impact issues.

[0101] After activating the anti-rollback function II, control is carried out in two ways. This ensures that the torque is preloaded in advance during the operation of the hill start assist system (HHC) to avoid untimely motor torque control, which could cause the vehicle to roll backward. If the hill start assist function is not activated, the driver presses the brake pedal, and the motor torque is applied to assist in preventing the vehicle from rolling backward, thus reducing the driver's fatigue from pressing the brake pedal.

[0102] Step 12: Determine whether the conditions for exiting the anti-slip slope function are met. If yes, proceed to Step 13; otherwise, continue with Step 12.

[0103] If any one of conditions 3a to 3g is met, the anti-rollback function is deactivated. Condition 3a is: the actual vehicle speed is greater than a preset second vehicle speed V2 and the accelerator pedal opening is greater than a preset accelerator pedal opening A1; in this embodiment, V2 = 3.0 km / h, A1 = 15%. Condition 3b is: the brake pedal is fully depressed (i.e., the brake pedal travel is greater than or equal to 90% of the total travel) and maintained for a second preset time t2; in this embodiment, t2 = 5s. Condition 3c is: a collision occurs. Condition 3d is: the handbrake is engaged. Condition 3e is: the gear is switched from D or R to a non-driving gear (i.e., P or N). Condition 3f is: (for vehicles equipped with radar or camera functions) the distance to the target ahead is less than a preset distance threshold B1; in this embodiment, B1 = 15cm. Condition 3g is: (for vehicles equipped with automatic emergency braking) the automatic emergency braking function (AEB function) is activated.

[0104] Step 13: Exit the anti-slide function (if anti-slide function I was activated previously, exit anti-slide function I; if anti-slide function II was activated previously, exit anti-slide function II), and then end.

[0105] This embodiment also provides a vehicle that includes the above-described auxiliary control system for preventing electric vehicles from rolling backwards.

[0106] Example 2: The auxiliary control system for preventing electric vehicles from rolling back on a slope in this example is the same as in Example 1. Most of the steps of the auxiliary control method for preventing electric vehicles from rolling back on a slope in this example are the same as in Example 1, except that:

[0107] The method for determining the first torque T1 is as follows: First, obtain the vehicle mass and the slope (i.e., the slope of the road where the vehicle is located); then, based on the absolute value of the vehicle mass and the slope, use linear interpolation to look up a preset first torque table to obtain the corresponding first torque T1. The preset first torque table is a table showing the correspondence between the absolute value of the vehicle mass and the slope and the first torque, obtained through experiments. The vehicle mass is a positive value and cannot be negative; therefore, the greater the vehicle mass, the greater the first torque. The slope can have positive and negative values; when the vehicle is facing downhill, the slope is negative, and when the vehicle is facing uphill, the slope is positive; the greater the absolute value of the slope, the greater the first torque. Calculating the first torque using linear interpolation can reduce some experimental and testing conditions, thus lowering R&D costs.

[0108] Example 3: The auxiliary control system for preventing electric vehicles from rolling back on a slope in this example is the same as in Example 1. Most of the steps of the auxiliary control method for preventing electric vehicles from rolling back on a slope in this example are the same as in Example 1, except that:

[0109] Requesting motor controller 2 to smoothly output the first torque T1 means requesting motor controller 2 to increase the torque output by the motor from 0 to the first torque T1 through first-order or second-order filtering. This filtering method ensures both the responsiveness and smoothness of the first torque loading, preventing vehicle impact issues.

[0110] The request for motor controller 2 to control the motor to continuously and smoothly output the second torque T2 within the first preset time t0 refers to: the request for motor controller 2 to control the output torque of the motor to increase from 0 to T through first-order filtering or second-order filtering. int And continue for t1, after which the torque is filtered from T by a first-order or second-order filter. int Change to T comp And continue from t0 to t1. By using filtering, both the responsiveness of the second torque and the smoothness of its loading can be ensured, thus avoiding impact problems on the vehicle.

[0111] Requesting motor controller 2 to smoothly output the third torque T3 means requesting motor controller 2 to increase the output torque of the motor from 0 to the third torque T3 through first-order or second-order filtering. This filtering method ensures both the responsiveness and smooth loading of the third torque, preventing vehicle impact issues.

[0112] This embodiment also provides a storage medium storing a computer-readable program, which, when invoked, can execute the steps of the auxiliary control method for preventing electric vehicles from rolling back, as described in this embodiment.

[0113] It should be noted that the storage medium described in this embodiment can be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium can be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, optical fiber, portable compact disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, carrying a computer-readable computer program. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media can also be any computer-readable medium other than computer-readable storage media, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The computer program contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to wireless, wired, etc., or any suitable combination thereof.

Claims

1. An auxiliary control method for preventing electric vehicles from rolling backwards, characterized in that, include: When the anti-slip slope function I is activated, if the absolute value of the slope is less than or equal to the first preset slope S1, the first torque T1 is determined and the control motor is requested to smoothly output the first torque T1; if the absolute value of the slope is greater than the first preset slope S1, the electronic parking brake system is requested to maintain clamping. When the anti-slip function II is activated, if the hill assist function is activated by pressing the brake pedal and the brake pedal is released, the second torque T2 is determined, and the control motor is requested to continuously and smoothly output the second torque T2 within the first preset time t0; if the hill assist function is not activated by pressing the brake pedal, the third torque T3 is determined, and the control motor is requested to smoothly output the third torque T3; wherein, the first preset time t0 is equal to the hill assist function holding time. The anti-slide function will be deactivated if the conditions for deactivation are met. The method for determining the second torque T2 is as follows: Obtain the gradient and actual vehicle speed; Using the formula: Calculate the second torque T2; T int This represents the torque in the first stage, and the duration of the torque in the first stage is t1, T int =k1×T crp k1 represents the correction factor, T crp T represents creep torque. comp This represents the second-stage torque, which lasts from t0 to t1. T is calculated using a PI closed-loop calculation based on the difference between the actual vehicle speed and the preset starting speed. comp The duration t1 of the torque in the first stage is obtained by consulting a preset timetable based on the absolute value of the slope. The preset timetable is a table showing the correspondence between the absolute value of the slope and time obtained through calibration. The correction coefficient k1 is obtained by consulting a preset correction coefficient table based on the absolute value of the slope. The correction coefficient table is a table showing the correspondence between the absolute value of the slope and correction coefficient obtained through calibration. The creep torque T is obtained by consulting a preset creep torque table based on the actual vehicle speed. crp The preset creep torque table is a table showing the correspondence between vehicle speed and creep torque obtained through calibration.

2. The auxiliary control method for preventing electric vehicles from rolling backwards according to claim 1, characterized in that, The method for determining the first torque T1 is as follows: Obtain vehicle weight and gradient; Substitute the absolute values ​​of the vehicle mass and the gradient into the preset torque curve to calculate the corresponding first torque T1; The preset torque curve is a curve showing the relationship between the absolute value of the first torque, the vehicle mass, and the slope, obtained by using a numerical fitting method based on the test data of the vehicle mass, the absolute value of the slope, and the first torque.

3. The auxiliary control method for preventing electric vehicles from rolling backwards according to claim 1, characterized in that, The method for determining the first torque T1 is as follows: Obtain vehicle weight and gradient; The first torque T1 is obtained by using linear interpolation to look up the preset first torque table based on the absolute values ​​of the vehicle mass and the slope. The preset first torque table is a table showing the correspondence between the absolute values ​​of the vehicle mass and slope obtained through testing and the first torque.

4. The auxiliary control method for preventing electric vehicles from rolling backwards according to claim 1, characterized in that: The request to control the motor to continuously and smoothly output the second torque T2 within the first preset time t0 means that the torque output by the requested control motor increases from 0 according to the first gradient a to T. int And continue for t1, after which the torque from T int According to the second gradient b, change to T comp And continue from t0 to t1; wherein, the first gradient a is obtained by querying the preset first gradient table based on the absolute values ​​of the vehicle mass and the slope, and the second gradient b is obtained by querying the preset second gradient table based on the absolute values ​​of the vehicle mass and the slope; the preset first gradient table is a table of correspondence between the first gradient obtained through calibration and the absolute values ​​of the vehicle mass and the slope; the preset second gradient table is a table of correspondence between the second gradient obtained through calibration and the absolute values ​​of the vehicle mass and the slope.

5. The auxiliary control method for preventing electric vehicles from rolling backwards according to claim 1, characterized in that: The request to control the motor to continuously and smoothly output the second torque T2 within the first preset time t0 means that the torque output by the requested control motor is increased from 0 to T through first-order or second-order filtering. int And continue for t1, after which the torque is filtered from T by a first-order or second-order filter. int Change to T comp And continue from t0 to t1.

6. The auxiliary control method for preventing electric vehicles from rolling backwards according to claim 1, characterized in that, The method for determining the third torque T3 is as follows: Obtain actual vehicle speed, gradient, and brake pedal travel; The initial torque T is obtained by referring to the preset initial torque table based on the absolute values ​​of the actual vehicle speed and gradient. s The preset initial torque table is a table showing the correspondence between the absolute values ​​of the actual vehicle speed and gradient and the initial torque, obtained through calibration. The correction factor k2 is obtained by querying the preset correction factor table based on the brake pedal travel; where the preset correction factor table is a table showing the correspondence between the brake pedal travel and the correction factor obtained through calibration. Use the formula: T3=k2×T s The third torque T3 is calculated.

7. The auxiliary control method for preventing electric vehicles from rolling backwards according to any one of claims 1 to 6, characterized in that: Requesting the smooth output of the first torque T1 by the control motor means requesting the torque output by the control motor to increase from 0 to the first torque T1 according to the third gradient c; wherein, the third gradient c is obtained by querying the preset third gradient table based on the absolute values ​​of the vehicle mass and the slope, and the preset third gradient table is a table of correspondence between the third gradient obtained through calibration and the absolute values ​​of the vehicle mass and the slope. Requesting the smooth output of the third torque T3 by the control motor means requesting the torque output by the control motor to increase from 0 to the third torque T3 according to the fourth gradient d; wherein, the fourth gradient d is obtained by querying the preset fourth gradient table based on the absolute values ​​of the vehicle mass and the slope, and the preset fourth gradient table is a table of correspondence between the fourth gradient obtained through calibration and the absolute values ​​of the vehicle mass and the slope.

8. The auxiliary control method for preventing electric vehicles from rolling backwards according to any one of claims 1 to 6, characterized in that: Requesting smooth output of the first torque T1 from the motor means requesting that the torque output of the motor be increased from 0 to the first torque T1 through first-order or second-order filtering. Requesting smooth output of the third torque T3 from the motor means requesting that the torque output of the motor be increased from 0 to the third torque T3 through first-order or second-order filtering.

9. The auxiliary control method for preventing electric vehicles from rolling backwards according to any one of claims 1 to 6, characterized in that: If conditions 1a to 1e are met simultaneously, it indicates that the conditions for activating anti-slide function I are met, and anti-slide function I will be activated; among them, Condition 1a is: the gear is switched from P to D or R; Condition 1b is: when switching to D gear, the slope is greater than or equal to S2; or when switching to R gear, the slope is less than or equal to -S2; where S2 represents the second preset slope, 0 < S2 < S1; Condition 1c is: the actual vehicle speed is less than or equal to the preset first vehicle speed V1; Condition 1d is: the accelerator pedal is not depressed; Condition 1e is: No faults affecting motor torque; If conditions 2a to 2g are met simultaneously, it indicates that the conditions for activating the anti-slide function II are met, and the anti-slide function II will be activated; among them, Condition 2a is: the gear is D or R; Condition 2b is: when in D gear, the slope is greater than or equal to S2; or when in R gear, the slope is less than or equal to -S2. Condition 2c is: the actual vehicle speed is less than or equal to the preset first vehicle speed V1; Condition 2d is: the accelerator pedal is not depressed; Condition 2e is: the handbrake is not engaged; Condition 2f is: Automatic parking function is not activated; Condition 2g is: no faults affecting motor torque; If any one of conditions 3a to 3g is met, it indicates that the anti-slide function exit condition is met; among them, Condition 3a is: the actual vehicle speed is greater than the preset second vehicle speed V2 and the accelerator pedal opening is greater than the preset accelerator opening A1; Condition 3b is: the brake pedal is fully depressed and maintained for a second preset time t2; Condition 3c is: A collision failure occurs; Condition 3D is: Handbrake engaged; Condition 3e is: the gear is switched from D or R to a non-driving gear; Condition 3f is: the distance to the target ahead is detected to be less than the preset distance threshold B1; Condition 3g is: Automatic emergency braking function activated.

10. An auxiliary control system for preventing electric vehicles from rolling backwards, comprising an auxiliary controller (1), characterized in that: The auxiliary controller (1) is programmed to perform the auxiliary control method for preventing electric vehicles from rolling back as described in any one of claims 1 to 9.

11. A vehicle, characterized in that: Includes the auxiliary control system for preventing electric vehicles from rolling backwards as described in claim 10.

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