A creep control method and device for electric vehicle

Abstract

The present invention discloses a creep control method and device for an electric vehicle, which obtains the chassis speed, front drive speed, rear drive speed and gearbox speed of the vehicle; screens and processes the chassis speed, front drive speed, rear drive speed and gearbox speed to determine the actual speed; determines the initial creep torque according to the difference between the actual speed and the preset vehicle creep speed; obtains the slope value of the current road condition, and determines the correction torque according to the slope value, the actual speed and the initial creep torque; obtains the braking signal of the vehicle, and pre-processes the braking signal to calculate the braking attenuation coefficient; determines the target creep torque for controlling the motor response according to the braking attenuation coefficient and the correction torque. In this way, the method solves the problem of unexpected acceleration of creep by pre-processing the three aspects of vehicle speed, slope and braking, and greatly improves the safety of low-speed driving of the vehicle.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicle control, and in particular to a method and device for controlling creep of an electric vehicle. Background Art

[0002] When the existing electric vehicles are in D / R gear, if the driver does not step on the accelerator or release the brake, the vehicle will output creep torque according to the difference between the actual speed and the target speed, and move forward or backward at a lower speed. However, it is also easy to have abnormal speed data (for example, the speed data value is less than the actual speed) or abnormal brake signal due to network communication or sensor failure, resulting in the creep torque not decaying normally with the speed and brake pressure, which in turn causes the safety problem of the vehicle accelerating all the time. Summary of the invention

[0003] In view of the above problems, the present invention is proposed to provide a method and device for controlling creeping of electric vehicles. By preprocessing the three signals of actual vehicle speed, slope and braking, the problem of unexpected acceleration of creeping is solved, and the safety of low-speed driving of the vehicle is greatly improved.

[0004] According to a first aspect of the present invention, there is provided a method for controlling creeping of an electric vehicle, comprising:

[0005] Obtain the vehicle's chassis speed, front-wheel drive speed, rear-wheel drive speed, and transmission speed;

[0006] The chassis speed, front-wheel drive speed, rear-wheel drive speed and transmission speed are screened and processed to determine the actual vehicle speed;

[0007] Determining an initial creep torque according to a difference between an actual vehicle speed and a preset vehicle creep speed;

[0008] Obtain the slope value of the current road condition, and determine the correction torque according to the slope value, the actual vehicle speed and the initial creep torque;

[0009] Obtaining the braking signal of the vehicle, preprocessing the braking signal, and calculating the braking attenuation coefficient;

[0010] According to the brake attenuation coefficient and the correction torque, the target creep torque for controlling the motor response is determined.

[0011] Optionally, the correction torque is determined according to the slope value, the actual vehicle speed and the initial creep torque, including:

[0012] Determine a slope correction coefficient according to the actual vehicle speed and a preset first mapping table;

[0013] Determine and obtain a slope compensation torque according to the slope value and a preset second mapping table;

[0014] The correction torque is determined according to the initial creep torque, the slope compensation torque and the correction coefficient.

[0015] Optionally, the correction torque is determined according to the initial creep torque, the slope compensation torque and the correction coefficient, including:

[0016] According to the initial creep torque, slope compensation torque and correction coefficient, the correction torque is determined by the following formula:

[0017] T q_mid =T q_raw +T q_slop ×R2

[0018] Among them, T q_mid is the correction torque, T q_raw is the initial creep torque, T q_slop is the slope compensation torque, and R2 is the correction coefficient.

[0019] Optionally, determining a target creep torque for controlling the motor response according to the brake attenuation coefficient and the correction torque includes:

[0020] According to the braking attenuation coefficient and the correction torque, the target creep torque for controlling the motor response is determined by the following formula:

[0021] T q_fin =T q_mid ×(1-R1)

[0022] Among them, T q_fin is the target creep torque, R1 is the braking attenuation coefficient, T q_mid To correct the torque.

[0023] Optionally, the brake signal includes hydraulic brake torque, brake pedal travel, and brake pedal switch state;

[0024] The braking signal of the vehicle is obtained, and the braking signal is pre-processed to calculate the braking attenuation coefficient, including:

[0025] When the hydraulic braking torque is effective, a braking attenuation coefficient is determined according to the hydraulic braking torque and a preset third mapping table;

[0026] When the hydraulic brake torque is invalid and the brake pedal stroke is valid, a brake attenuation coefficient is determined according to the brake pedal stroke and a preset fourth mapping table;

[0027] When the hydraulic brake torque is invalid, the brake pedal stroke is invalid, and the brake pedal switch state is valid, the brake attenuation coefficient is determined according to the brake pedal switch state.

[0028] Optionally, the brake attenuation coefficient is determined according to the brake pedal switch state, including:

[0029] If the brake pedal switch is in the pressed state, the brake attenuation coefficient is set to 100%;

[0030] If the brake pedal switch state is not depressed, the brake attenuation coefficient is set to 0%.

[0031] Optionally, the chassis speed, the front drive speed, the rear drive speed and the transmission speed are filtered to determine the actual vehicle speed, including:

[0032] determining the driver's desired direction based on the vehicle's gear position;

[0033] Taking the expected direction as a reference direction, determining updated chassis speed, front drive speed, rear drive speed and transmission speed;

[0034] Subtract the offset value from the updated front-wheel drive speed, rear-wheel drive speed, and transmission speed to obtain the processed front-wheel drive speed, rear-wheel drive speed, and transmission speed;

[0035] The updated chassis speed is compared with the processed front-wheel drive speed, rear-wheel drive speed and transmission speed, and the speed with the largest value is selected as the actual speed.

[0036] According to a second aspect of the present invention, there is provided an electric vehicle creep control device, characterized in that it comprises:

[0037] An acquisition module is used to acquire the chassis speed, front drive speed, rear drive speed and transmission speed of the vehicle;

[0038] A screening and processing module is used to screen and process the chassis speed, the front drive speed, the rear drive speed and the transmission speed to determine the actual vehicle speed;

[0039] A first processing module, used for determining an initial creep torque according to a difference between an actual vehicle speed and a preset vehicle creep speed;

[0040] A correction module is used to obtain the slope value of the current road condition, and determine the correction torque according to the slope value, the actual vehicle speed and the initial creep torque;

[0041] The second processing module is used to obtain the braking signal of the vehicle, pre-process the braking signal, and calculate the braking attenuation coefficient;

[0042] The third processing module is used to determine a target creep torque for controlling the motor response according to the brake attenuation coefficient and the correction torque.

[0043] According to a third aspect of the present invention, an electronic device is provided, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the aforementioned electric vehicle creep control method when executing the computer program.

[0044] According to a fourth aspect of the present invention, an electric vehicle is provided, and the electric vehicle applies the above-mentioned electric vehicle creep control method.

[0045] The above one or more technical solutions in the embodiments of this specification have at least the following technical effects:

[0046] The embodiments of this specification provide a creep control method and device for an electric vehicle, which obtains the chassis speed, front drive speed, rear drive speed and transmission speed of the vehicle; screens and processes the chassis speed, front drive speed, rear drive speed and transmission speed to determine the actual speed; determines the initial creep torque according to the difference between the actual speed and the preset vehicle creep speed; obtains the slope value of the current road condition, and determines the correction torque according to the slope value, the actual speed and the initial creep torque; obtains the braking signal of the vehicle, and pre-processes the braking signal to calculate the braking attenuation coefficient; determines the target creep torque for controlling the motor response according to the braking attenuation coefficient and the correction torque. In this way, by pre-processing the speeds from different sources, any excessive speed will attenuate the creep target torque to 0Nm to avoid unexpected creep acceleration on a flat road. It can also attenuate the slope compensation to zero when the vehicle speed is high to avoid unexpected creep acceleration on a slope. At the same time, based on the redundant processing of multiple braking signals, unexpected acceleration during braking can be avoided. This method solves the problem of unexpected acceleration during creeping by preprocessing vehicle speed, slope and braking, greatly improving the safety of low-speed driving of the vehicle.

[0047] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] By reading the detailed description of the preferred embodiment below, various other advantages and benefits will become clear to those of ordinary skill in the art. The accompanying drawings are only used for the purpose of illustrating the preferred embodiment and are not considered to be limiting of the present invention. Moreover, the same reference figures are used to represent the same parts throughout the accompanying drawings.

[0049] In the attached picture:

[0050] Figure 1 A schematic diagram of an electronic device in an embodiment of the present invention is shown.

[0051] Figure 2 A flow chart of a creep control method for an electric vehicle in an embodiment of the present invention is shown.

[0052] icon:

[0053] 100 - electronic device; 10 - electric vehicle creep control device; 20 - memory; 30 - processor; 40 - communication unit. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0055] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0057] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] See also Figure 1 , Figure 1 FIG. 1 is a structural block diagram of an electronic device 100 provided in this embodiment. Figure 1 As shown, the electronic device may include an electric vehicle creep control device 10, a memory 20, a processor 30 and a communication unit 40. The memory 20 stores machine-readable instructions executable by the processor 30. When the electronic device 100 is running, the processor 30 and the memory 20 communicate through a bus, and the processor 30 executes the machine-readable instructions and executes the electric vehicle creep control method.

[0059] The memory 20, the processor 30 and the communication unit 40 are electrically connected to each other directly or indirectly to achieve signal transmission or interaction. For example, these components can be electrically connected to each other through one or more communication buses or signal lines. The electric vehicle creep control device 10 includes at least one software function module that can be stored in the memory 20 in the form of software or firmware. The processor 30 is used to execute the executable module stored in the memory 20 (for example, the software function module or computer program included in the electric vehicle creep control device 10).

[0060] Among them, the memory 20 can be, but is not limited to, random access memory (Random Access Memory, RAM), read only memory (Read Only Memory, ROM), programmable read-only memory (Programmable Read-Only Memory, PROM), erasable programmable read-only memory (Erasable Programmable Read-Only Memory, EPROM), electrically erasable read-only memory (Electric Erasable Programmable Read-Only Memory, EEPROM), etc.

[0061] In some embodiments, the processor 30 is used to perform one or more functions described in this embodiment. In some embodiments, the processor 30 may include one or more processing cores (eg, a single-core processor (S) or a multi-core processor (S)).

[0062] For ease of explanation, only one processor is described in the electronic device 100. However, it should be noted that the electronic device 100 in this embodiment may also include multiple processors, so the steps performed by one processor described in this embodiment may also be performed jointly or individually by multiple processors. For example, if the processor of the server executes step A and step B, it should be understood that step A and step B may also be performed jointly by two different processors or individually in one processor. For example, the processor executes step A and the second processor executes step B, or the processor and the second processor execute steps A and B together.

[0063] In this embodiment, the memory 20 is used to store programs, and the processor 30 is used to execute the programs after receiving execution instructions. The process definition method disclosed in any implementation of this embodiment can be applied to the processor 30 or implemented by the processor 30.

[0064] The communication unit 40 is used to establish a communication connection between the electronic device 100 and other devices through a network, and to send and receive data through the network. In some embodiments, the network can be any type of wired or wireless network, or a combination thereof.

[0065] In this embodiment, the electronic device 100 may be, but is not limited to, a cloud server, a vehicle controller, etc. This embodiment does not impose any restrictions on the specific type of the electronic device.

[0066] based on Figure 1 The present embodiment provides a creep control method for an electric vehicle. Figure 1 The electronic device 100 shown is implemented in combination with Figure 2 As shown, the electric vehicle creep control method includes steps 101 to 106:

[0067] Step 101: Obtain the chassis speed, front drive speed, rear drive speed and transmission speed of the vehicle;

[0068] Among them, the chassis speed is calculated based on the wheel speed and direction of the four wheels, with the front direction as the standard, forward is positive and backward is negative; the front-wheel drive speed is calculated based on the front motor speed and direction, the front reducer transmission ratio, and the tire radius. With the front direction as the standard, forward is positive and backward is negative; the rear-wheel drive speed is calculated based on the rear motor speed and direction, the rear reducer transmission ratio, and the tire radius. With the front direction as the standard, forward is positive and backward is negative; the transmission speed is calculated based on the transmission output shaft speed and direction, the reducer transmission ratio, and the tire radius when the clutch is engaged. With the front direction as the standard, forward is positive and backward is negative, and it is only applicable to hybrid vehicles with transmissions. It should be noted that not all models have front-wheel drive speed, rear-wheel drive speed, and transmission speed. Most models only have some of the speed values. If there are no other speed values, the other speed values ​​are invalid, that is, they do not need to be considered.

[0069] For example, for a non-hybrid four-wheel drive vehicle, there are only chassis speed, front-wheel drive speed, and rear-wheel drive speed. When obtaining the vehicle speed, these three speeds are valid values, and the transmission speed is an invalid value, so there is no need to consider the transmission speed. For a hybrid four-wheel drive vehicle, there are chassis speed, front-wheel drive speed, rear-wheel drive speed, and transmission speed. When obtaining the vehicle speed, these four speeds are all valid values.

[0070] Step 102: screening the chassis speed, the front-wheel drive speed, the rear-wheel drive speed and the transmission speed to determine the actual vehicle speed;

[0071] Among them, after obtaining the above four vehicle speed values, the four vehicle speed values ​​need to be pre-processed, that is, screened, to obtain the actual vehicle speed. The purpose of the screening process is to avoid the failure of the sensor that detects the vehicle speed, which leads to abnormal vehicle speed data. In the prior art, the vehicle speed is mostly based on the chassis speed. When the sensor that detects the vehicle speed is normal, whether it is the chassis speed, the front drive speed, the rear drive speed, or the transmission speed, the actual speed of the whole vehicle represented by it is roughly the same; however, if the sensor that detects the vehicle speed fails, the detected speed data will be wrong. If the speed data is less than the actual speed, the creep torque will continue to increase, causing unexpected acceleration of creep and affecting driving safety. Therefore, this embodiment adds the front drive speed, the rear drive speed and the transmission speed. These three speeds are more of a testing function.

[0072] In specific implementation, one of the vehicle speeds can be used as the main speed, and the other speeds can be used as the verification speed. For example, the chassis speed is used as the main speed, and the front-wheel drive speed, rear-wheel drive speed, and transmission speed are used as verification to ensure that the actual speed is obtained. Specific steps may include:

[0073] determining the driver's desired direction based on the vehicle's gear position;

[0074] Taking the expected direction as a reference direction, determining updated chassis speed, front drive speed, rear drive speed and transmission speed;

[0075] Subtract the offset value from the updated front-wheel drive speed, rear-wheel drive speed, and transmission speed to obtain the processed front-wheel drive speed, rear-wheel drive speed, and transmission speed;

[0076] The updated chassis speed is compared with the processed front-wheel drive speed, rear-wheel drive speed and transmission speed, and the speed with the largest value is selected as the actual speed.

[0077] This embodiment mainly uses chassis speed, and other speeds are used as verification. When driving a vehicle, the driver will determine the gear position of the vehicle. For example, if the gear position of the vehicle is D gear, the driver will use the front direction of the vehicle as the desired direction; after the gear position of the vehicle is switched to R gear, the driver will use the rear direction of the vehicle as the desired direction, that is, the reverse direction as the desired direction. Taking the desired direction as the reference direction, taking the chassis speed as an example, if it is D gear, the chassis speed and other speeds are multiplied by 1 respectively, and if it is R gear, the chassis speed and other speeds are multiplied by -1 respectively. For example, when the vehicle is on a slope and the gear position is D gear, and the vehicle slides down the slope and drives backward, the chassis speed after processing is -3km / h.

[0078] The main purpose of determining the desired direction is to be able to promptly identify when the vehicle is sliding on a slope through the updated vehicle speed. For example, in some mountainous cities, most urban roads are slopes. When the driver is driving or parking, if the gear is in D gear, and the vehicle is sliding down the slope and driving backwards, if the updated chassis speed or front drive speed or rear drive speed or transmission speed is approximately -3km / h, it can be determined that the vehicle is sliding down the slope. The actual vehicle speed value will affect the creep torque output by the subsequent vehicle. The speed of this sliding situation can be overcome by the output creep torque.

[0079] In addition, in order to distinguish the primary and secondary vehicle speeds, an offset value is preset, and the value of the offset value is small, for example, the offset value is 1km / h, or even smaller. Compare the updated chassis speed with the processed front-wheel drive speed, rear-wheel drive speed, and transmission speed, and select the speed with the largest value as the actual speed. In this way, when the detected speed values ​​are normal, the chassis speed is used as the actual speed; when there is a problem with the chassis speed detection, it may be too large or too small. If the detected chassis speed is too large, the chassis speed is used as the actual speed, and the creep torque determined later will not be too large, and the creep torque determined may even be 0. If the chassis speed is too small, the speed with the larger value among the processed front-wheel drive speed, rear-wheel drive speed, and transmission speed shall prevail. In this way, when the vehicle speed is fast and the chassis speed deviates and is displayed as small, the vehicle will not continuously output creep torque to avoid unexpected acceleration of creep.

[0080] Step 103: determining an initial creep torque according to a difference between the actual vehicle speed and a preset vehicle creep speed;

[0081] Among them, after determining the actual vehicle speed, the actual vehicle speed will be compared with the preset vehicle creeping speed. The preset vehicle creeping speed may be different for different vehicle models. In this embodiment, the vehicle creeping speed can be set to 5km / h. The actual vehicle speed is generally less than the vehicle creeping speed. According to the difference between the two, the torque to be provided is determined, and this torque refers to the initial creeping torque. It should be noted that the initial creeping torque is not the creeping torque ultimately output by the vehicle. Other factors need to be considered for torque correction in the future.

[0082] In this embodiment, a mapping table of initial creep torque and difference is provided, and the corresponding initial creep torque can be obtained by looking up the table.

[0083] Step 104: Obtain the slope value of the current road condition, and determine the correction torque according to the slope value, the actual vehicle speed and the initial creep torque;

[0084] The slope value of the current road condition can be estimated based on the acceleration deviation according to the collected vehicle speed and acceleration, which belongs to the prior art. A slope measurement sensor can also be installed in the vehicle to detect the slope value.

[0085] After the slope value is determined, the correction torque can be determined according to the slope value, the actual vehicle speed and the initial creep torque. The specific steps include:

[0086] Determine a slope correction coefficient according to the actual vehicle speed and a preset first mapping table;

[0087] Determine and obtain a slope compensation torque according to the slope value and a preset second mapping table;

[0088] The correction torque is determined according to the initial creep torque, the slope compensation torque and the correction coefficient.

[0089] Specifically, the first mapping table refers to the mapping relationship between the actual vehicle speed and the slope correction coefficient. After determining the actual vehicle speed, the slope correction coefficient corresponding to the actual vehicle speed can be found through the first mapping table. For example, the slope correction coefficient unit is %, the vehicle creep speed is 5km / h, and when the actual vehicle speed V _act When ≤1km / h, the corresponding slope correction coefficient is 100%; the actual vehicle speed V _act =2km / h, the corresponding slope correction factor is 50%, and the actual vehicle speed V _act When the speed is ≥4km / h, the corresponding slope correction coefficient is 0%. The purpose of this setting is to perform slope compensation on the initial creep torque only at low vehicle speeds, and not to perform slope compensation on the initial creep torque at high speeds (greater than or equal to the vehicle creep speed), so as to avoid the existence of compensation torque at high speeds, resulting in unexpected acceleration.

[0090] Similarly, the second mapping table refers to the relationship between the slope value and the slope compensation torque. After the slope value is determined, the slope compensation torque corresponding to the slope value can be determined by searching the second mapping table. It should be noted that both the actual vehicle speed and the slope correction coefficient, and the slope value and the slope compensation torque, are calibrated based on relevant road tests.

[0091] After determining the initial creep torque, slope compensation torque and correction coefficient, the correction torque can be obtained by the following formula:

[0092] T q_mid =T q_raw +T q_slop ×R2

[0093] Among them, T q_mid is the correction torque, T q_raw is the initial creep torque, Tq_slop is the slope compensation torque, and R2 is the correction coefficient.

[0094] Step 105: obtaining a braking signal of the vehicle, preprocessing the braking signal, and calculating a braking attenuation coefficient;

[0095] The brake signal includes hydraulic brake torque, brake pedal travel, and brake pedal switch status. The brake pedal travel is denoted as L1, which refers to the pedal travel that the chassis responds to based on the driver's brake depth. It reflects the brake master cylinder pressure to a certain extent. It is 0-20mm with brake assist and 0-40mm without brake assist. The hydraulic brake torque is denoted as T q1 , refers to the braking torque converted by the chassis according to the actual hydraulic braking execution, in Nm. The brake pedal switch state is recorded as S t1 It refers to whether the brake pedal is depressed or not, which is obtained through arbitration based on the high and low level signals of the brake pedal switch sensor.

[0096] Optionally, the step of preprocessing the brake signal may include:

[0097] When the hydraulic braking torque is effective, a braking attenuation coefficient is determined according to the hydraulic braking torque and a preset third mapping table;

[0098] When the hydraulic brake torque is invalid and the brake pedal stroke is valid, a brake attenuation coefficient is determined according to the brake pedal stroke and a preset fourth mapping table;

[0099] When the hydraulic brake torque is invalid, the brake pedal stroke is invalid, and the brake pedal switch state is valid, the brake attenuation coefficient is determined according to the brake pedal switch state.

[0100] It should be noted that the brake signal has a priority when judging, that is, the priority is arranged from high to low as follows: hydraulic brake torque, brake pedal travel, brake pedal switch state.

[0101] That is, when T q1 When the signal is valid, the braking attenuation coefficient is calculated according to T q1 According to the preset third mapping table, the unit of the braking attenuation coefficient is %. For example, T q1 ≤100Nm, brake attenuation coefficient corresponds to 0%, T q1 =500Nm, the braking attenuation coefficient corresponds to 50%, T q1 ≥1000Nm, the brake attenuation coefficient corresponds to 100%;

[0102] When T q1 When the signal is invalid but the L1 signal is valid, the braking attenuation coefficient is obtained by looking up the preset fourth mapping table according to L1. The unit of the braking attenuation coefficient is %, and an example is as follows:

[0103] When there is brake assist: L1≤2mm, the brake attenuation coefficient corresponds to 0%, L1=5mm, the brake attenuation coefficient corresponds to 50%, L1≥10mm, the brake attenuation coefficient corresponds to 100%;

[0104] When there is no brake assist: L1≤3mm, the brake attenuation coefficient corresponds to 0%, when L1=7mm, the brake attenuation coefficient corresponds to 50%, when L1≥15mm, the brake attenuation coefficient corresponds to 100%;

[0105] When T q1 and L1 signals are invalid but S t1 When valid, it is processed as follows:

[0106] If the brake pedal switch S t1 If the brake is not pressed, the brake attenuation coefficient is set to 100%;

[0107] If the brake pedal switch S t1 If the brake pedal is not depressed, the brake fade coefficient is set to 0%.

[0108] Step 106: Determine the target creep torque for controlling the motor response according to the brake attenuation coefficient and the correction torque.

[0109] In this embodiment, the initial creep torque is corrected twice. The initial creep torque is corrected once according to the slope to obtain the corrected torque, and then the corrected torque is corrected again according to braking-related factors to obtain the final target creep torque. The target creep torque refers to the torque value sent to the motor to control the motor to respond.

[0110] In an optional implementation, according to the brake attenuation coefficient and the correction torque, the target creep torque for controlling the motor response can be determined by the following formula:

[0111] T q_fin =T q_mid ×(1-R1)

[0112] Among them, T q_fin is the target creep torque, R1 is the braking attenuation coefficient, T q_mid To correct the torque.

[0113] It is not difficult to understand that the correction torque is corrected again through braking, that is, the deeper the brake pedal is pressed, the larger the value of R1 is, even 100%, so that the target creep torque is smaller, even 0.

[0114] In summary, the embodiments of this specification provide a method for controlling creep of an electric vehicle. By processing the vehicle speeds from different sources, any excessive vehicle speed will attenuate the creep target torque to 0 Nm, thereby avoiding unexpected creep acceleration on a flat road. The method can also attenuate the slope compensation to zero when the vehicle speed is high to avoid unexpected creep acceleration on a slope. At the same time, it can also avoid unexpected acceleration during braking based on redundant processing of multiple braking signals. Ultimately, the problem of unexpected acceleration during creep is solved by preprocessing the vehicle speed, slope, and braking, greatly improving the safety of the vehicle when driving at low speeds.

[0115] Based on the same inventive concept, an embodiment of the present invention further provides an electric vehicle creep control device, comprising:

[0116] An acquisition module is used to acquire the chassis speed, front drive speed, rear drive speed and transmission speed of the vehicle;

[0117] A screening and processing module is used to screen and process the chassis speed, the front drive speed, the rear drive speed and the transmission speed to determine the actual vehicle speed;

[0118] A first processing module, used for determining an initial creep torque according to a difference between an actual vehicle speed and a preset vehicle creep speed;

[0119] A correction module is used to obtain the slope value of the current road condition, and determine the correction torque according to the slope value, the actual vehicle speed and the initial creep torque;

[0120] The second processing module is used to obtain the braking signal of the vehicle, pre-process the braking signal, and calculate the braking attenuation coefficient;

[0121] The third processing module is used to determine a target creep torque for controlling the motor response according to the brake attenuation coefficient and the correction torque.

[0122] Optionally, the correction torque is determined according to the slope value, the actual vehicle speed and the initial creep torque, including:

[0123] Determine a slope correction coefficient according to the actual vehicle speed and a preset first mapping table;

[0124] Determine and obtain a slope compensation torque according to the slope value and a preset second mapping table;

[0125] The correction torque is determined according to the initial creep torque, the slope compensation torque and the correction coefficient.

[0126] Optionally, the correction torque is determined according to the initial creep torque, the slope compensation torque and the correction coefficient, including:

[0127] According to the initial creep torque, slope compensation torque and correction coefficient, the correction torque is determined by the following formula:

[0128] T q_mid =T q_raw +T q_slop ×R2

[0129] Among them, T q_mid is the correction torque, T q_raw is the initial creep torque, T q_slop is the slope compensation torque, and R2 is the correction coefficient.

[0130] Optionally, determining a target creep torque for controlling the motor response according to the brake attenuation coefficient and the correction torque includes:

[0131] According to the braking attenuation coefficient and the correction torque, the target creep torque for controlling the motor response is determined by the following formula:

[0132] T q_fin =T q_mid ×(1-R1)

[0133] Among them, T q_fin is the target creep torque, R1 is the braking attenuation coefficient, T q_mid To correct the torque.

[0134] Optionally, the brake signal includes hydraulic brake torque, brake pedal travel, and brake pedal switch state;

[0135] The braking signal of the vehicle is obtained, and the braking signal is pre-processed to calculate the braking attenuation coefficient, including:

[0136] When the hydraulic braking torque is effective, a braking attenuation coefficient is determined according to the hydraulic braking torque and a preset third mapping table;

[0137] When the hydraulic brake torque is invalid and the brake pedal stroke is valid, a brake attenuation coefficient is determined according to the brake pedal stroke and a preset fourth mapping table;

[0138] When the hydraulic brake torque is invalid, the brake pedal stroke is invalid, and the brake pedal switch state is valid, the brake attenuation coefficient is determined according to the brake pedal switch state.

[0139] Optionally, the brake attenuation coefficient is determined according to the brake pedal switch state, including:

[0140] If the brake pedal switch is in the pressed state, the brake attenuation coefficient is set to 100%;

[0141] If the brake pedal switch state is not depressed, the brake attenuation coefficient is set to 0%.

[0142] Optionally, the chassis speed, the front drive speed, the rear drive speed and the transmission speed are filtered to determine the actual vehicle speed, including:

[0143] Subtract the offset value from the front-drive vehicle speed, the rear-drive vehicle speed, and the transmission speed to obtain updated front-drive vehicle speed, rear-drive vehicle speed, and transmission speed;

[0144] The chassis speed is compared with the updated front-wheel drive speed, rear-wheel drive speed and transmission speed, and the speed with the largest value is selected as the actual speed.

[0145] The embodiment of the present specification provides an electric vehicle creep control device, which obtains the chassis speed, front drive speed, rear drive speed and gearbox speed of the vehicle; screens and processes the chassis speed, front drive speed, rear drive speed and gearbox speed to determine the actual speed; determines the initial creep torque according to the difference between the actual speed and the preset vehicle creep speed; obtains the slope value of the current road condition, and determines the correction torque according to the slope value, the actual speed and the initial creep torque; obtains the braking signal of the vehicle, and pre-processes the braking signal to calculate the braking attenuation coefficient; determines the target creep torque for controlling the motor response according to the braking attenuation coefficient and the correction torque. In this way, by pre-processing the speeds from different sources, any excessive speed will attenuate the creep target torque to 0Nm to avoid unexpected creep acceleration on flat roads. It can also attenuate the slope compensation to zero when the vehicle speed is high to avoid unexpected creep acceleration on slopes. At the same time, based on the redundant processing of multiple braking signals, unexpected acceleration during braking can be avoided. This method solves the problem of unexpected acceleration during creeping by preprocessing vehicle speed, slope and braking, greatly improving the safety of low-speed driving of the vehicle.

[0146] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the electric vehicle creep control device described above can refer to the corresponding process in the aforementioned method, and will not be elaborated here.

[0147] On the basis of the above, this embodiment further provides an electric vehicle, in which a vehicle controller is provided, and the vehicle controller applies the above-mentioned electric vehicle creep control method.

[0148] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the electric vehicle described above can refer to the corresponding process in the aforementioned method, and will not be elaborated herein.

[0149] The above are only various embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A creep control method for an electric vehicle, characterized in that: include: Obtain the vehicle's chassis speed, front-wheel drive speed, rear-wheel drive speed, and transmission speed; Screening the chassis speed, front-wheel-drive speed, rear-wheel-drive speed, and transmission speed to determine the actual vehicle speed; Determining an initial creep torque according to a difference between an actual vehicle speed and a preset vehicle creep speed; Obtaining a slope value of a current road condition, and determining a correction torque according to the slope value, the actual vehicle speed, and the initial creep torque; Obtaining the braking signal of the vehicle, preprocessing the braking signal, and calculating the braking attenuation coefficient; Determining a target creep torque for controlling a motor response according to the brake attenuation coefficient and the correction torque; The brake signal includes hydraulic brake torque, brake pedal travel, and brake pedal switch state; The step of obtaining a braking signal of the vehicle, preprocessing the braking signal, and calculating a braking attenuation coefficient includes: When the hydraulic braking torque is valid, a braking attenuation coefficient is determined according to the hydraulic braking torque and a preset third mapping table; When the hydraulic brake torque is invalid and the brake pedal stroke is valid, a brake attenuation coefficient is determined according to the brake pedal stroke and a preset fourth mapping table; When the hydraulic brake torque is invalid, the brake pedal stroke is invalid, and the brake pedal switch state is valid, the brake attenuation coefficient is determined according to the brake pedal switch state.

2. The method according to claim 1, characterized in that The determining of the correction torque according to the slope value, the actual vehicle speed and the initial creep torque includes: Determining a slope correction coefficient according to the actual vehicle speed and a preset first mapping table; Determining a slope compensation torque according to the slope value and a preset second mapping table; The correction torque is determined according to the initial creep torque, the slope compensation torque and the correction coefficient.

3. The method according to claim 2, characterized in that The determining the correction torque according to the initial creep torque, the slope compensation torque and the correction coefficient comprises: According to the initial creep torque, the slope compensation torque and the correction coefficient, the correction torque is obtained by determining the correction torque using the following formula: T q_mid =T q_raw +T q_slop ×R2 Among them, T q_mid is the correction torque, T q_raw is the initial creep torque, T q_slop is the slope compensation torque, and R2 is the correction coefficient.

4. The method according to claim 1, characterized in that: The step of determining a target creep torque for controlling the motor response according to the brake attenuation coefficient and the correction torque includes: According to the braking attenuation coefficient and the correction torque, the target creep torque for controlling the motor response is determined by the following formula: T q_fin =T q_mid ×(1-R1) Among them, T q_fin is the target creep torque, R1 is the braking attenuation coefficient, T q_mid To correct the torque.

5. The method according to claim 1, characterized in that Determining the brake attenuation coefficient according to the brake pedal switch state includes: If the brake pedal switch is in the pressed state, the brake attenuation coefficient is set to 100%; If the brake pedal switch state is not depressed, the brake attenuation coefficient is set to 0%.

6. The method according to claim 1, characterized in that The screening and processing of the chassis speed, the front-drive speed, the rear-drive speed and the transmission speed to determine the actual speed includes: determining the driver's desired direction based on the vehicle's gear position; Taking the expected direction as a reference direction, determining updated chassis speed, front drive speed, rear drive speed and transmission speed; Subtract the offset value from the updated front-wheel drive speed, rear-wheel drive speed, and transmission speed to obtain the processed front-wheel drive speed, rear-wheel drive speed, and transmission speed; The updated chassis speed is compared with the processed front-wheel drive speed, rear-wheel drive speed and transmission speed, and the speed with the largest value is selected as the actual speed.

7. An electric vehicle creep control device, characterized in that: Using the electric vehicle creep control method according to any one of claims 1 to 6, the device comprises: An acquisition module is used to acquire the chassis speed, front drive speed, rear drive speed and transmission speed of the vehicle; A screening and processing module is used to screen and process the chassis speed, the front-drive speed, the rear-drive speed and the transmission speed to determine the actual vehicle speed; A first processing module, used for determining an initial creep torque according to a difference between an actual vehicle speed and a preset vehicle creep speed; A correction module, used for obtaining a slope value of a current road condition, and determining a correction torque according to the slope value, the actual vehicle speed and the initial creep torque; The second processing module is used to obtain the braking signal of the vehicle, pre-process the braking signal, and calculate the braking attenuation coefficient; The third processing module is used to determine a target creep torque for controlling the motor response according to the brake attenuation coefficient and the correction torque.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the electric vehicle creep control method according to any one of claims 1 to 6 are implemented.

9. An electric vehicle, characterized in that: The electric vehicle applies the electric vehicle creep control method as described in any one of claims 1-6.

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