A method and system for creep control of an electric vehicle

Abstract

This invention provides a method and system for controlling the creeping motion of electric vehicles. During the creeping start-up phase, the control motor enters torque mode, and the target torque of the motor is controlled in a closed loop. Based on the vehicle's state, considering the influence of factors such as electronic parking brake force, motor anti-rollover torque, gradient, and load, a base torque is determined to ensure normal and smooth starting of the vehicle under different conditions. The torque is adjusted through a fuzzy PID closed-loop system, allowing the vehicle to gradually accelerate towards the creeping target speed. Once the vehicle speed enters the creeping target speed range, the control motor enters speed mode, and the motor controller directly controls the motor to stabilize at the target speed, resulting in more direct and efficient control and ensuring stable vehicle operation. This control method ensures smooth creeping start-up control for the vehicle under different operating conditions, including unloaded, fully loaded, and parked conditions, and prevents frequent fluctuations in the creeping target speed.

Description

Technical Field

[0001] This invention relates to a creep control method and system, belonging to the field of electric vehicle technology. Background Technology

[0002] Crawl mode is a basic driving control mode for road vehicles. Typically, the vehicle automatically maintains a stable low speed without the driver applying the brakes, primarily used for starting and slow following. Crawl control in electric vehicles generally uses closed-loop PID control of the drive motor's torque to ensure the vehicle travels at the target crawl speed. However, PID control is prone to overshoot, fluctuations, and large errors, mainly due to improper selection of PID controller parameters and the influence of changes in vehicle load, gradient, and other operating conditions.

[0003] The main challenge in creep mode for electric light trucks is cargo transportation. How to control the smoothness of creep start and the stability of final speed under different working conditions such as empty, half-loaded, fully loaded, and climbing is an important problem to be solved in achieving creep control on light trucks.

[0004] In the prior art:

[0005] Patent CN202211606256.8 discloses a creep control method for pure electric heavy-duty trucks. After entering creep mode, it employs dynamic PID control and adds feedforward torque based on slope and load to achieve target creep speed control under different slopes and loads. However, this patent does not consider the vehicle being in automatic parking or motor anti-rollover mode on slopes. If the initial torque and PID parameters are not set reasonably, vehicle rollover can easily occur.

[0006] Patent CN202110011293.3 discloses an automatic starting control system and method for a pure electric loader. After meeting the creep control conditions, it ensures a smooth start by giving a starting torque value and controlling the torque change step size. However, this patent does not consider the changes in the vehicle's working conditions under different slopes and loads, and the torque adjustment is adjusted by the step size change.

[0007] Patent CN202210614450.4 discloses a method for maintaining slope by combining VCU creep torque control with EPB parking brake. After the slope meets the creep control conditions, creep PID torque control begins, simultaneously calculating the PID parameters and feedforward torque for preventing slippage. When slippage occurs, it seamlessly switches to the anti-slippage torque. However, this patent does not consider the impact of load; in actual execution, the VCU needs to simultaneously control the EPB braking torque.

[0008] Patent CN201910982374.0 discloses a method for controlling parking, creeping, and creeping speed limit of an electric vehicle, in which the VCU controls the release of parking mode and creeping speed limit control. However, the creeping torque calculation in this patent does not take into account changes in operating conditions such as load, slope, and electronic parking brake.

[0009] In other publicly disclosed patents in the prior art, the calculation of creep torque does not fully consider vehicle status information, including load, gradient, motor anti-rollover, electronic parking, etc. Furthermore, it does not take into account the characteristics of motor speed and torque control mode to switch control modes in a timely manner. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and system for controlling the creep of electric vehicles, so as to ensure that the vehicle can achieve smooth control of creep start under different vehicle conditions and prevent the vehicle from fluctuating frequently at the creep target speed.

[0011] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0012] In a first aspect, the present invention provides a method for controlling the creeping motion of an electric vehicle, comprising the following steps:

[0013] Step A: Obtain vehicle information and determine the vehicle status based on the vehicle information;

[0014] Step B: Based on the vehicle status, determine whether the creep trigger condition is met. If yes, proceed to step C; otherwise, proceed to step A.

[0015] Step C: Enter crawling control mode;

[0016] Step D: Determine if the crawling exit condition is met. If yes, proceed to step E; otherwise, proceed to step C.

[0017] Step E: Exit creep control, obtain the target torque of the motor, and control the motor to enter torque mode.

[0018] Furthermore, the vehicle status includes normal starting status, hill parking status, motor anti-rollover status, and driving status.

[0019] Furthermore, the vehicle status is determined based on vehicle information, including:

[0020] When the vehicle information simultaneously meets the following detection conditions:

[0021] The gear is not in neutral;

[0022] The accelerator pedal opening is 0;

[0023] The brake pedal opening is 0.

[0024] The motor speed is 0;

[0025] The motor torque is 0;

[0026] The electronic parking force is 0.

[0027] This is judged to be a normal start-up state;

[0028] When the vehicle information simultaneously meets the following detection conditions:

[0029] The absolute value of the slope is greater than the threshold of 2°;

[0030] The gear is not in neutral;

[0031] The accelerator pedal opening is 0;

[0032] The motor speed is 0;

[0033] The motor torque is 0;

[0034] Electronic parking force is greater than 0;

[0035] The vehicle is judged to be parked on a slope.

[0036] When the vehicle information simultaneously meets the following detection conditions:

[0037] The absolute value of the slope is greater than the threshold of 2°;

[0038] The gear is not in neutral;

[0039] The accelerator pedal opening is 0;

[0040] The motor speed is 0;

[0041] The motor torque is not zero;

[0042] The electronic parking force is 0.

[0043] The motor is determined to be in anti-slip condition.

[0044] When the vehicle information simultaneously meets the following detection conditions:

[0045] The gear is not in neutral;

[0046] The motor speed is not 0;

[0047] It is determined to be in a driving state.

[0048] Furthermore, based on the vehicle status, it is determined whether the creep triggering conditions are met, including:

[0049] If the vehicle is in a normal starting state, the creep trigger condition is met;

[0050] If the vehicle is parked on a slope, the creep trigger condition is met when the throttle opening is detected to be greater than 2%.

[0051] If the vehicle is in motor anti-rollover mode, the creep trigger condition is met when the throttle opening is detected to be greater than 2%.

[0052] If the vehicle is in motion, when the throttle opening is 0, the brake pedal opening is 0, and the vehicle speed is less than the creep target speed, the creep trigger condition is met.

[0053] The target crawling speed is defined by the manufacturer and should not exceed 5 km / h.

[0054] Furthermore, entering the crawling control mode includes:

[0055] Step C1: Obtain the initial torque value T i ;

[0056] Step C2: Obtain the torque coefficient k;

[0057] Step C3: Based on the initial torque value T i And the torque coefficient k, calculate the basic torque value T b ;

[0058] Step C4: Obtain the torque value T of the fuzzy PID closed-loop control p ;

[0059] Step C5: Based on the basic torque value T b And the torque value T of fuzzy PID closed-loop control p Obtain the target torque T of the motor t This controls the motor to enter torque mode;

[0060] Step C6: Determine whether the creep target speed has been reached. If yes, proceed to step C7; otherwise, proceed to step C4.

[0061] Step C7: Obtain the target motor speed n t This controls the motor to enter speed mode.

[0062] Further, in step C1, the initial torque value T is obtained. i ,include:

[0063] T i =T f +T s

[0064] T f This is the torque value of the vehicle overcoming friction on a flat road, which is obtained from actual vehicle testing.

[0065] T S This is the torque value obtained based on the recorded vehicle status.

[0066] If the vehicle is in a normal starting or driving state, then T S =0.

[0067] If the vehicle is in a hill-start assist position, then F h denoted as electronic parking force, r as wheel radius, and i as reduction ratio from motor to wheel.

[0068] If the vehicle is in motor anti-rollover mode, then T S =T m1 T m1 The torque value fed back by the motor to prevent slippage on a slope.

[0069] Step C2, obtaining the torque coefficient k, including:

[0070] The torque coefficient k is a coefficient greater than 1. The greater the vehicle load, the greater the torque coefficient k. This value is obtained from actual vehicle testing.

[0071] Step C3, based on the initial torque value T i And the torque coefficient k, calculate the basic torque value T b ,include:

[0072] Basic torque value T b It is the product of the initial torque value and the torque coefficient, i.e.

[0073] T b = T i *k

[0074] Step C4: Obtain the torque value T of the fuzzy PID closed-loop control. p ,include:

[0075] Obtain the creeping target vehicle speed V t and current vehicle speed V c ;

[0076] Based on the creep target vehicle speed V t and current vehicle speed V c The torque value T of the fuzzy PID closed-loop control is calculated using the following formula. p :

[0077]

[0078] In the formula, err(t) = V t -V c The target speed for crawling is V. t and current vehicle speed V c The difference;

[0079] K p - Proportioning factor

[0080] T i-Integral time coefficient

[0081] T d - Differential time coefficient

[0082] The above coefficients were selected using a fuzzy control algorithm, taking the vehicle speed error err(t) and the error change rate as the basis. As input, fuzzy inference is performed using fuzzy control rules to adjust PID parameters in real time.

[0083] Furthermore, obtain the creeping target vehicle speed V. t and current vehicle speed V c ,include:

[0084] Obtain the preset creep target speed as the creep target speed V. t ;

[0085] The current vehicle speed is calculated using the following formula:

[0086]

[0087] n is the motor speed (r / min), which is obtained through a speed sensor;

[0088] r is the wheel radius, in meters;

[0089] i is the total transmission ratio from the motor to the wheel;

[0090] V c The current vehicle speed is expressed in km / h.

[0091] Further, in step C5, the target torque T of the motor is obtained. t To control the motor to enter torque mode, including:

[0092] The target torque T of the motor is calculated using the following formula. t :

[0093] T t =T b +T p

[0094] The motor operates in torque mode, with the vehicle controller controlling the motor torque. The executed torque is the acquired target motor torque T. t .

[0095] Calculate vehicle acceleration If the acceleration value is greater than the preset maximum vehicle acceleration value 'a' max , that is, a>a max Then the execution torque is the correction value of the above-mentioned target torque of the motor.

[0096]

[0097] Step C6: Determine if the target creep speed has been reached. If yes, proceed to step C7; otherwise, proceed to step C4, including:

[0098] Get the current vehicle speed;

[0099] If the current vehicle speed V c ≥V t If the duration exceeds t seconds, it indicates that the vehicle speed has reached the target creep speed range. At this point, step C7 is executed; otherwise, step C4 is executed to continue fuzzy PID closed-loop control.

[0100] Step C7, obtain the target motor speed n t To control the motor to enter speed mode, including:

[0101] Obtain the target speed n of the motor t Control the motor to enter speed mode.

[0102] n t This is the motor speed value corresponding to the target crawling speed. At this time, the motor is controlled to work in speed mode, and the motor controller controls the motor to stabilize at the target speed.

[0103] Further, determine whether the crawling exit condition is met. If yes, proceed to step E; otherwise, proceed to step C, including:

[0104] If the vehicle is already in crawl control mode, determine whether the exit conditions are met:

[0105] The acceleration torque required by the accelerator pedal is 10 Nm greater than the actual torque value of the current motor.

[0106] The brake pedal opening is greater than 0;

[0107] The current vehicle speed exceeds the maximum crawl speed;

[0108] The direction of the motor speed is inconsistent with the gear position;

[0109] If any of the above exit conditions are met, exit the crawling control mode and execute step E; otherwise, continue to execute step C and maintain the crawling control mode.

[0110] Furthermore, exiting creep control, acquiring the target torque of the motor, and controlling the motor to enter torque mode includes:

[0111] After exiting the crawl control mode, the motor enters torque mode, where the target torque value of the motor is the acceleration torque demand value corresponding to the accelerator pedal.

[0112] Secondly, the present invention provides an electric vehicle crawl control system, including a load sensor, an tilt sensor, a brake pedal, an accelerator pedal, a gear shift lever, a vehicle controller, an electronic parking unit, an MCU, and a motor.

[0113] The load sensor is connected to the vehicle controller and is used to detect the weight of the vehicle.

[0114] The tilt sensor is connected to the vehicle controller and is used to detect the slope of the vehicle.

[0115] The brake pedal is connected to the vehicle controller and is used for vehicle braking needs.

[0116] The accelerator pedal is connected to the vehicle controller and is used to meet the vehicle's acceleration requirements.

[0117] The gear shift lever is connected to the vehicle controller and is used for vehicle gear switching;

[0118] The vehicle controller is connected to the load sensor, tilt sensor, brake pedal, accelerator pedal, gear shift lever, vehicle controller, electronic parking brake unit, and MCU, and is used to execute the creep control method described in the first aspect.

[0119] The MCU is connected to the vehicle controller and the motor, and is used to receive vehicle control commands and control the motor to output corresponding torque or speed in response to torque mode or speed mode.

[0120] The electronic parking unit is connected to the vehicle controller and is used for automatic vehicle parking and feedback of parking force.

[0121] The motor is connected to the MCU and is used to execute drive or braking torque.

[0122] Torque mode and speed mode are the basic operating modes of the MCU. In torque mode, the MCU receives VCU commands and controls the motor to adjust the corresponding torque output; in speed mode, the MCU receives VCU commands and controls the motor to adjust the corresponding speed output.

[0123] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0124] 1. The creep control method of this application takes into account vehicle status information and combines the characteristics of motor speed and torque control mode to switch control mode in a timely manner, so as to ensure that the vehicle can achieve smooth creep start control under different vehicle conditions and prevent the vehicle from fluctuating frequently at the creep target speed.

[0125] 2. This application determines the vehicle's state before entering creep control based on vehicle information. Based on different vehicle states, loads, and gradients, it calculates the initial creep torque value to prevent insufficient motor torque during vehicle start-up under varying loads and gradients. During creep control mode, fuzzy PID closed-loop control is continuously performed to correct the target motor torque, achieving smooth creep control of the vehicle.

[0126] 3. In this application, during creep start-up and acceleration, the motor operates in torque control mode, with the vehicle controller calculating the target torque to prevent insufficient torque, overshoot, or excessively rapid torque changes. Once the vehicle speed stabilizes within the target creep speed range, the motor switches to speed control mode, with the motor controller (MCU) controlling the motor to operate stably at the target speed. This control is more direct and efficient, reducing the computational burden on the vehicle controller. The computational steps are clearly defined, simple, and reliable. Furthermore, it can be added to existing vehicle models. Attached Figure Description

[0127] Figure 1 Diagram of a crawl control system for electric vehicles;

[0128] Figure 2 Flowchart for crawl control of electric vehicles;

[0129] Figure 3 This is a flowchart of the control process for the crawl motor of an electric vehicle. Detailed Implementation

[0130] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0131] Example 1:

[0132] This embodiment provides a method for controlling the crawling motion of an electric vehicle, such as... Figure 2 As shown.

[0133] Step S1: Determine vehicle status

[0134] Based on vehicle information, the vehicle's status can be categorized as follows:

[0135] ① Normal starting state

[0136] The following testing conditions must be met simultaneously:

[0137] The gear is not in neutral;

[0138] The accelerator pedal opening is 0;

[0139] The brake pedal opening is 0.

[0140] The motor speed is 0;

[0141] The motor torque is 0;

[0142] The electronic parking force is 0.

[0143] ② Parking on a ramp

[0144] The following testing conditions must be met simultaneously:

[0145] The absolute value of the slope is greater than the threshold of 2°;

[0146] The gear is not in neutral;

[0147] The accelerator pedal opening is 0;

[0148] The motor speed is 0;

[0149] The motor torque is 0;

[0150] Electronic parking force is greater than 0;

[0151] ③ Motor anti-slip condition

[0152] The following testing conditions must be met simultaneously:

[0153] The absolute value of the slope is greater than the threshold of 2°;

[0154] The gear is not in neutral;

[0155] The accelerator pedal opening is 0;

[0156] The motor speed is 0;

[0157] The motor torque is not zero;

[0158] The electronic parking force is 0.

[0159] (④ Driving status)

[0160] The gear is not in neutral;

[0161] The motor speed is not 0;

[0162] Step S2: Determine if the creep triggering condition is met.

[0163] Determine whether to trigger the crawl control mode based on the vehicle's current status.

[0164] If the vehicle is in a normal starting state, it will directly enter the crawl control mode;

[0165] If the vehicle is parked on a slope, it will enter crawl control mode when the throttle opening is detected to be greater than 2%.

[0166] If the vehicle is in motor anti-rollover mode, it will enter creep control mode when the throttle opening is detected to be greater than 2%.

[0167] If the vehicle is in motion, when the throttle opening is 0, the brake pedal opening is 0, and the vehicle speed is less than the creep target speed, the creep control mode is entered.

[0168] The target crawl speed is defined by the manufacturer and is usually no higher than 5 km / h. The target crawl speed can be obtained by reading or inputting a preset value.

[0169] Step S3: After the crawl triggering conditions are met, the vehicle enters the crawl control mode.

[0170] Step S31: Obtain the initial torque value T based on the vehicle status. i

[0171] T f This is the torque value of a vehicle overcoming friction on a flat road, which is usually obtained from actual vehicle testing.

[0172] T S This is the torque value obtained based on the recorded vehicle status.

[0173] If the vehicle is in a normal starting or driving state, then T S =0.

[0174] If the vehicle is in a hill-start assist position, then F h denoted as electronic parking force, r as wheel radius, and i as reduction ratio from motor to wheel.

[0175] If the vehicle is in motor anti-rollover mode, then T S =T m1 T m1 The torque value fed back by the motor to prevent slippage on a slope.

[0176] Step S32: Obtain the torque coefficient k based on the vehicle load.

[0177] The torque coefficient k is a coefficient greater than 1. The greater the vehicle load, the greater the torque coefficient k. This value is usually obtained from actual vehicle testing.

[0178] Step S33, calculate the basic torque value T b

[0179] This value is the product of the initial torque value and the torque coefficient, i.e.

[0180] T b =T i *k

[0181] Step S34: Obtain the torque value T of the fuzzy PID closed-loop control. p

[0182]

[0183] In the formula, err(t) = V t -V c The target speed for crawling is V. t and current vehicle speed V c The difference

[0184] K p - Proportioning factor

[0185] T i -Integral time coefficient

[0186] T d - Differential time coefficient

[0187] The above coefficients were selected using a fuzzy control algorithm, taking the vehicle speed error err(t) and the error change rate as the basis. As input, fuzzy inference is performed using fuzzy control rules to adjust PID parameters in real time.

[0188] The following formula can be used to calculate vehicle speed.

[0189] The current vehicle speed is calculated using the following formula:

[0190]

[0191] r is the wheel radius, in meters;

[0192] i is the total transmission ratio from the motor to the wheel;

[0193] V c The current vehicle speed is expressed in km / h.

[0194] n - Motor speed (r / min): The MCU collects the motor speed through the speed sensor and sends the speed value to the communication bus, so that the vehicle controller can obtain the motor speed from the communication bus.

[0195] Step S35, obtain the target torque T of the motor. t Control the motor to enter torque mode

[0196] T t =T b +T p

[0197] The motor operates in torque mode, with the vehicle controller controlling the motor torque. The executed torque is the acquired target motor torque T. t The target torque variation can be adjusted according to the vehicle's acceleration requirements.

[0198] Calculate vehicle acceleration If the acceleration value is greater than the preset maximum vehicle acceleration value 'a' max , that is, a>a maxThen the execution torque is the correction value of the above-mentioned target torque of the motor.

[0199]

[0200] The torque mode and speed mode of a motor are its basic operating modes. In torque mode, the motor torque output is adjusted according to VCU commands; in speed mode, the motor speed output is adjusted according to VCU commands.

[0201] Step S36: Determine whether the target creep speed has been reached.

[0202] If the current vehicle speed V c ≥V t If the duration exceeds t seconds, it indicates that the vehicle speed has reached the target creep speed range. At this time, step S37 is executed; otherwise, step S34 is executed to continue fuzzy PID closed-loop control.

[0203] Step S37, obtain the target motor speed n t Control the motor to enter speed mode

[0204] n t This is the motor speed value corresponding to the target crawling speed. At this time, the motor is controlled to work in speed mode, and the motor controller controls the motor to stabilize at the target speed.

[0205] Step S4: Determine whether the crawling exit condition is met.

[0206] If the vehicle is already in crawl control mode, determine whether the exit conditions are met:

[0207] ① The acceleration torque required by the accelerator pedal is 10 Nm greater than the actual torque value of the current motor.

[0208] ② Brake pedal opening greater than 0

[0209] ③ The current vehicle speed exceeds the maximum crawl speed.

[0210] ④ The direction of motor speed is inconsistent with the gear position.

[0211] Once any of the above conditions are met, you need to exit the crawling control mode and execute step S5; otherwise, continue to maintain the crawling control mode.

[0212] Step S5: Exit creep control, obtain the target torque of the motor, and control the motor to enter torque mode.

[0213] After exiting the crawl control mode, the motor enters the torque mode, where the target torque value of the motor is the acceleration torque required by the accelerator pedal.

[0214] The creep control method of this application takes into account vehicle status information and combines the characteristics of motor speed and torque control mode to switch control modes in a timely manner, so as to ensure that the vehicle can achieve smooth creep start control under different vehicle conditions and prevent the vehicle from fluctuating frequently at the creep target speed.

[0215] This application determines the vehicle's state before entering creep control based on vehicle information. Based on different vehicle states, loads, and gradients, it calculates the initial creep torque value to prevent insufficient motor torque during vehicle start-up under varying loads and gradients. During creep control mode, fuzzy PID closed-loop control is continuously performed to correct the motor's target torque, achieving smooth creep control of the vehicle.

[0216] In this application, during creep start-up and acceleration, the motor operates in torque control mode, with the vehicle controller calculating the target torque to prevent insufficient torque, overshoot, or excessively rapid torque changes. Once the vehicle speed stabilizes within the target creep speed range, the motor switches to speed control mode, with the motor controller (MCU) controlling the motor to operate stably at the target speed. This control is more direct and efficient, reducing the computational burden on the vehicle controller. The computational steps are clearly defined, simple, and reliable. Furthermore, it can be added to existing vehicle models.

[0217] In addition, it should be noted that:

[0218] The current vehicle speed used in this invention is calculated from the motor speed fed back by the motor controller, or it can be obtained through sensors such as wheel speed sensors, acceleration sensors, or GPS, and is also within the scope of protection of this patent.

[0219] When calculating the required torque, this invention uses a fuzzy PID control algorithm as the implementation scheme. Alternatively, sliding mode control algorithm, variable proportional PID control algorithm, etc., can also be used. As long as the required torque is obtained through closed-loop control of vehicle speed, it falls within the protection scope of this patent.

[0220] Example 2:

[0221] This embodiment provides a crawling control system for electric vehicles, such as... Figure 1 As shown, it includes a load sensor, tilt sensor, brake pedal, accelerator pedal, gear shift lever, vehicle controller, electronic parking brake unit, MCU, and motor.

[0222] The load sensor is connected to the vehicle controller and is used to detect the weight of the vehicle.

[0223] The tilt sensor is connected to the vehicle controller and is used to detect the slope of the vehicle.

[0224] The brake pedal is connected to the vehicle controller and is used for vehicle braking needs.

[0225] The accelerator pedal is connected to the vehicle controller and is used to meet the vehicle's acceleration requirements.

[0226] The gear shift lever is connected to the vehicle controller and is used for vehicle gear switching;

[0227] The vehicle controller is connected to the load sensor, tilt sensor, brake pedal, accelerator pedal, gear shift lever, vehicle controller, electronic parking brake unit, and MCU, and executes the creep control method described in Embodiment 1 of the present invention.

[0228] The MCU is connected to the vehicle controller and the motor, and is used to receive vehicle control commands and control the motor to output corresponding torque or speed in response to torque mode or speed mode.

[0229] The electronic parking unit is connected to the vehicle controller and is used for automatic vehicle parking and feedback of parking force.

[0230] The motor is connected to the MCU and is used to execute drive or braking torque.

[0231] Note that torque mode and speed mode are the basic operating modes of the MCU. In torque mode, the MCU receives VCU commands to control the motor to adjust the corresponding torque output; in speed mode, the MCU receives VCU commands to control the motor to adjust the corresponding speed output.

[0232] The MCU collects the motor speed through the speed sensor and sends the speed value to the communication bus, so that the vehicle controller can obtain the motor speed from the communication bus.

[0233] During creep start-up and acceleration, the motor operates in torque control mode, where the vehicle controller calculates the target torque to prevent insufficient torque, overshoot, or excessive torque fluctuations. Once the vehicle speed stabilizes within the target creep speed range, the motor switches to speed control mode, where the MCU controls the motor to operate stably at the target speed. This more direct and efficient control reduces the computational burden on the vehicle controller.

[0234] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0235] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0236] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0237] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0238] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An electric vehicle inching control method characterized by, Includes the following steps: Step A: Obtain vehicle information and determine the vehicle status based on the vehicle information; Step B: Based on the vehicle status, determine whether the creep trigger condition is met. If yes, proceed to step C; otherwise, proceed to step A. Step C: Enter crawling control mode; Step D: Determine if the crawling exit condition is met. If yes, proceed to step E; otherwise, proceed to step C. Step E: Exit creep control, obtain the target torque of the motor, and control the motor to enter torque mode; The vehicle status includes normal starting status, hill parking status, motor anti-rollover status, and driving status. Entering crawl control mode includes: Step C1 : Obtain initial torque value ; Step C2: Obtain torque coefficient ; Step C3: Calculate the base torque value based on the initial torque value and the torque coefficient ;​ Step C4: Acquire the fuzzy PID closed-loop control torque value ; Step C5: according to the base torque value and the fuzzy PID closed-loop control torque value , obtain the motor target torque , control the motor to enter the torque mode; Step C6: Determine whether the creep target speed has been reached. If yes, proceed to step C7; otherwise, proceed to step C4. Step C7: Obtain motor target speed , control motor to enter speed mode.

2. The electric vehicle crawl control method of claim 1, wherein, The vehicle status is determined based on vehicle information, including: When the vehicle information simultaneously meets the following detection conditions: The gear is not in neutral; The accelerator pedal opening is 0; The brake pedal opening is 0. The motor speed is 0; The motor torque is 0; The electronic parking force is 0. This is then judged as a normal starting state; And / or, When the vehicle information simultaneously meets the following detection conditions: The absolute value of the slope is greater than the threshold of 2°; The gear is not in neutral; The accelerator pedal opening is 0; The motor speed is 0; The motor torque is 0; Electronic parking force is greater than 0; This indicates the vehicle is parked on a slope. And / or, When the vehicle information simultaneously meets the following detection conditions: The absolute value of the slope is greater than the threshold of 2°; The gear is not in neutral; The accelerator pedal opening is 0; The motor speed is 0; The motor torque is not zero; The electronic parking force is 0. Then it is determined that the motor is in anti-slip condition; And / or, When the vehicle information simultaneously meets the following detection conditions: The gear is not in neutral; The motor speed is not 0; Then it is determined to be in a driving state.

3. The electric vehicle crawl control method of claim 1, wherein, Based on the vehicle status, determine whether the creep trigger conditions are met, including: If the vehicle is in a normal starting state, the creep trigger condition is met; If the vehicle is parked on a slope, the creep trigger condition is met when the throttle opening is detected to be greater than 2%. If the vehicle is in motor anti-rollover mode, the creep trigger condition is met when the throttle opening is detected to be greater than 2%. If the vehicle is in motion, when the throttle opening is 0, the brake pedal opening is 0, and the vehicle speed is less than the creep target speed, the creep trigger condition is met.

4. The electric vehicle crawl control method of claim 1, wherein, Step C1, obtaining initial torque value comprising: ； The torque value for the vehicle to overcome the friction on the flat road is obtained from the real vehicle test. a torque value obtained from a recorded vehicle state; If the vehicle state is normal start state, running state, then ; If the vehicle is in a hill-start assist position, then , For electronic parking brake, For the wheel radius, This is the reduction ratio from the motor to the wheels; If the vehicle state is the motor anti-slip state, then , is the torque value fed back by the motor when anti-slip. And / or, Step C2, obtaining torque coefficient , comprising: Torque coefficient is a coefficient greater than 1, the greater the vehicle load, the greater the torque coefficient This value is obtained from real vehicle tests; And / or, Step C3, calculating a base torque value based on the initial torque value and the torque coefficient , comprises: calculating a base torque value based on the initial torque value a base torque value is the initial torque value and a torque coefficient is the product of, namely ； And / or, Step C5, based on the basic torque value And fuzzy PID closed-loop control torque value Obtain the target torque of the motor To control the motor to enter torque mode, including: The target torque of the motor is calculated using the following formula. : ； The motor is controlled to operate in a torque mode, and the motor torque is controlled by the vehicle controller to execute the torque obtained as the motor target torque ; Calculating vehicle acceleration If the acceleration value is greater than a preset maximum vehicle acceleration value Then a correction value of the torque is executed as the above motor target torque ； And / or, Step C6: Determine if the target creep speed has been reached. If yes, proceed to step C7; otherwise, proceed to step C4, including: Get the current vehicle speed; If the current vehicle speed and the duration exceeds seconds, it means that the vehicle speed has run to the target crawling target speed interval, at which time step C7 is executed, otherwise step C4 is executed, and the fuzzy PID closed-loop control continues. And / or, Step C7, obtaining the target rotating speed of the motor controlling the motor to enter the rotating speed mode, comprising: Obtaining a target rotational speed of a motor controlling the motor to enter a rotational speed mode, This is the motor speed value corresponding to the target crawling speed. At this time, the motor is controlled to work in speed mode, and the motor controller controls the motor to stabilize at the target speed.

5. The electric vehicle crawl control method of claim 4, wherein, Step C4, acquire the fuzzy PID closed-loop control torque value , comprising: acquiring a target vehicle speed for crawling and a current vehicle speed ; According to the target vehicle speed for crawling and the current vehicle speed , the fuzzy PID closed-loop control torque value is calculated by the following formula : ； In the formula is a target vehicle speed for crawling and the difference between the current vehicle speed and the current vehicle speed - a proportionality coefficient - integration time coefficient - differential time coefficient The selection of the above coefficients is obtained by using a fuzzy control algorithm, taking the vehicle speed error and the error change rate erṙ(t) as inputs, using fuzzy control rules to perform fuzzy reasoning and adjust the PID parameters in real time. Get the target speed for crawling and current vehicle speed ,include: acquiring a preset target vehicle speed as the target vehicle speed ; The current vehicle speed is calculated using the following formula: ； For the motor speed, obtained by the speed sensor; r is the radius of the wheel; i is the total transmission ratio from the motor to the wheel; V c V is the current vehicle speed.

6. The electric vehicle crawl control method of claim 1, wherein, Determine if the crawling exit condition is met. If yes, proceed to step E; otherwise, proceed to step C, including: If the vehicle is already in crawl control mode, determine whether the exit conditions are met: The acceleration torque required by the accelerator pedal is 10 Nm greater than the actual torque value of the current motor. The brake pedal opening is greater than 0; The current vehicle speed exceeds the maximum crawl speed; The direction of the motor speed is inconsistent with the gear position; If any of the above exit conditions are met, exit the crawling control mode and execute step E; otherwise, continue to execute step C and maintain the crawling control mode.

7. The electric vehicle crawl control method of claim 1, wherein, Exit creep control, acquire the target torque of the motor, and control the motor to enter torque mode, including: After exiting the crawl control mode, the motor enters the torque mode, where the target torque value of the motor is the acceleration torque required by the accelerator pedal.

8. An electric vehicle inching control system characterized by, This includes load cells, tilt sensors, brake pedals, accelerator pedals, gear shift levers, vehicle controllers, electronic parking brake units, MCUs, and motors. The load sensor is connected to the vehicle controller and is used to detect the weight of the vehicle. The tilt sensor is connected to the vehicle controller and is used to detect the slope of the vehicle. The brake pedal is connected to the vehicle controller and is used for vehicle braking needs. The accelerator pedal is connected to the vehicle controller and is used to meet the vehicle's acceleration requirements. The gear shift lever is connected to the vehicle controller and is used for vehicle gear switching; The vehicle controller is connected to the load sensor, tilt sensor, brake pedal, accelerator pedal, gear shift lever, vehicle controller, electronic parking unit, and MCU, and is used to execute the creep control method as described in any one of claims 1-7; The MCU is connected to the vehicle controller and the motor, and is used to receive vehicle control commands and control the motor to output corresponding torque or speed in response to torque mode or speed mode. The electronic parking unit is connected to the vehicle controller and is used for automatic vehicle parking and feedback of parking force. The motor is connected to the MCU and is used to execute drive or braking torque.

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