A method and system for controlling electric vehicle downhill coasting
By dynamically distributing electric braking and mechanical braking torque, combined with battery recovery capability and the motor's minimum negative torque capability, the problem of wheel lock-up in the downhill slow-moving control of electric vehicles has been solved, achieving improved stability and safety on low-adhesion road surfaces.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DONGFENG MOTOR GRP
- Filing Date
- 2026-04-16
- Publication Date
- 2026-06-12
AI Technical Summary
Existing methods for controlling downhill driving in electric vehicles cannot simultaneously address energy recovery, braking safety, and stability on low-adhesion surfaces, and are particularly prone to wheel lock-up under high absolute value electric braking negative torque.
By acquiring real-time vehicle status parameters, the total target braking torque is calculated. Based on the principle of prioritizing electric braking, combined with battery recovery capability and the minimum negative torque capability of the motor, the basic electric braking negative torque and mechanical braking torque are dynamically allocated. PID closed-loop control is then performed based on the maximum slip ratio to correct the electric braking torque and prevent wheel lock-up.
While prioritizing energy recovery and range, it effectively avoids wheel lock-up caused by large absolute value electric braking negative torque on low-adhesion roads, thus improving the stability and safety of downhill driving.
Smart Images
Figure CN122186084A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electric vehicle control technology, and in particular to a method and system for controlling the slow-moving motion of an electric vehicle downhill. Background Technology
[0002] When a vehicle descends a long, steep slope, the tangential component of gravity causes the vehicle to accelerate continuously. If the driver does not brake in time, this can easily lead to speeding up the slope. Descending slowly involves the VCU (Vehicle Control Unit) actively applying electric or mechanical braking to keep the actual vehicle speed below the free acceleration speed, ensuring driving safety.
[0003] Current downhill braking control systems generally employ an electric braking priority strategy: the total target braking torque is primarily achieved through the negative torque of the electric motor, with mechanical braking supplementing any excess electric braking capacity. While this approach benefits energy recovery and range, it has significant drawbacks: on low-adhesion surfaces, a large absolute value of electric braking negative torque can easily lead to wheel lock-up, resulting in loss of directional stability and braking efficiency.
[0004] Therefore, existing technologies cannot simultaneously address energy recovery, braking safety, and stability on low-adhesion road surfaces. There is an urgent need for a downhill slow-moving control method and system that can dynamically allocate electric braking and mechanical braking to prevent wheel lock-up. Summary of the Invention
[0005] The present invention aims to solve at least one of the technical problems existing in the prior art, and proposes a method and system for controlling the slow-moving speed of electric vehicles downhill.
[0006] In a first aspect, embodiments of the present invention provide a method for controlling downhill descent of an electric vehicle, comprising:
[0007] Obtain real-time vehicle status parameters and calculate the total target braking torque for slow downhill driving.
[0008] Based on the principle of prioritizing electric braking, and combining the battery recovery capacity and the minimum negative torque capacity of the motor, the minimum electric braking capacity boundary is determined; and based on the total target braking torque and the minimum capacity boundary, the basic electric braking negative torque and the basic mechanical braking torque are allocated.
[0009] Collect the wheel speeds of the four wheels and calculate the vehicle's current maximum slip ratio;
[0010] Calculate the electric braking correction torque based on the maximum slip ratio;
[0011] The target electric braking negative torque and the target mechanical braking torque are calculated based on the electric braking correction torque.
[0012] Furthermore, the total target braking torque for downhill descent is calculated, specifically by obtaining the tangential component torque T of gravity. G and speed control correction torque T v， The total target braking torque for slow downhill driving was calculated. , .
[0013] Furthermore, the speed control corrects the torque T. v The acquisition method includes: obtaining the current downhill gradient value; looking up a table based on the current gradient value to obtain a target vehicle speed related to the gradient value; calculating the difference between the target vehicle speed and the actual vehicle speed to obtain the speed control deviation; and obtaining the speed control correction torque based on the speed control deviation through PI control. .
[0014] Furthermore, based on the total target braking torque and the minimum capacity boundary, the basic electric braking negative torque and the basic mechanical braking torque are allocated, specifically including:
[0015] When the target braking torque Minimum capability boundary At this time, the target braking torque is entirely borne by the electric brake, and the mechanical brake does not work; therefore, the basic electric brake has a negative torque. = Mechanical braking torque = 0Nm;
[0016] When the target braking torque Minimum capability boundary At that time, the electric brake operates at maximum capacity. The output is supplemented by mechanical braking if insufficient; therefore, the basic electric braking negative torque is... Basic mechanical braking torque .
[0017] Furthermore, the basic electric braking negative torque Basic mechanical braking torque The total braking torque remains unchanged.
[0018] Furthermore, the formula for calculating the vehicle's current maximum slip ratio is:
[0019]
[0020] in, For reference speed, Let be the minimum wheel speed of the four wheels; where:
[0021]
[0022] in, The left front wheel, The right front wheel, It is the left rear wheel. It is the right rear wheel.
[0023] Furthermore, the method for calculating the electric braking correction torque based on the maximum slip ratio includes:
[0024] When the maximum slip ratio exceeds the preset slip ratio threshold and exceeds the preset time, the vehicle controller activates closed-loop control of the slip ratio; the slip ratio deviation is calculated. , ; For the maximum slip ratio, To achieve a target slip ratio that improves vehicle stability, PID closed-loop control is implemented based on the slip ratio deviation Δλ to obtain the electric braking correction torque. .
[0025] Furthermore, the target electric braking negative torque and the target mechanical braking torque are calculated based on the electric braking correction torque. Specific methods include:
[0026] Target electric braking negative torque Equal to the basic electric braking negative torque Add corrected torque ,Right now
[0027] Target electric braking negative torque Target mechanical braking torque Equal to the basic mechanical braking torque Add corrected torque That is, the target mechanical braking torque The target electric braking negative torque and the target mechanical braking torque are respectively sent to the motor controller and the braking control system for execution.
[0028] Secondly, the present invention also discloses an electric vehicle downhill easing control system, comprising: a total target braking torque calculation unit, a basic electric braking negative torque and basic mechanical braking torque calculation unit, a maximum slip ratio calculation unit, an electric braking correction torque calculation unit, and a target electric braking negative torque and target mechanical braking torque calculation unit; wherein:
[0029] The total target braking torque calculation unit is used to acquire real-time vehicle status parameters and calculate the total target braking torque for slow downhill driving.
[0030] The basic electric braking negative torque and basic mechanical braking torque calculation unit is used to determine the minimum electric braking capacity boundary based on the principle of electric braking priority, combined with the battery recovery capacity and the minimum negative torque capacity of the motor; and to allocate the basic electric braking negative torque and basic mechanical braking torque according to the total target braking torque and the minimum capacity boundary.
[0031] The maximum slip ratio calculation unit is used to collect the wheel speeds of the four wheels and calculate the vehicle's current maximum slip ratio.
[0032] An electric braking correction torque calculation unit is used to calculate the electric braking correction torque based on the maximum slip ratio;
[0033] The target electric braking negative torque and target mechanical braking torque calculation unit is used to calculate the target electric braking negative torque and target mechanical braking torque based on the electric braking correction torque.
[0034] Thirdly, the present invention also discloses an electronic device comprising:
[0035] One or more processors;
[0036] Memory, used to store one or more programs;
[0037] When the one or more programs are executed by the one or more processors, the one or more processors implement the control method.
[0038] This invention discloses a downhill descent control method for electric vehicles, belonging to the technical field of downhill descent control for electric vehicles. The method includes: acquiring real-time vehicle status parameters and calculating the total target braking torque for downhill descent; determining the minimum electric braking capacity boundary based on the principle of prioritizing electric braking, combined with battery recovery capability and the minimum negative torque capability of the motor; allocating a basic electric braking negative torque and a basic mechanical braking torque according to the total target braking torque and the minimum capacity boundary; collecting the wheel speeds of the four wheels and calculating the vehicle's current maximum slip ratio; calculating the electric braking correction torque based on the maximum slip ratio; and calculating the target electric braking negative torque and the target mechanical braking torque based on the electric braking correction torque. This invention, while prioritizing energy recovery and range capability, effectively avoids wheel lock-up on low-adhesion surfaces due to large absolute values of electric braking negative torque, improving downhill driving stability and safety. It is applicable to downhill cruise control and off-road downhill scenarios for pure electric and hybrid vehicles equipped with both electric and mechanical braking. Attached Figure Description
[0039] Figure 1 This is a flowchart illustrating a method for controlling downhill driving of an electric vehicle according to an embodiment of the present invention.
[0040] Figure 2 This is a structural block diagram of an electric vehicle downhill easing control system provided in an embodiment of the present invention;
[0041] Figure 3 This is a structural block diagram of an electronic device provided in an embodiment of the present invention. Detailed Implementation
[0042] To enable those skilled in the art to better understand the technical solutions of the present invention, exemplary embodiments of the present invention are described below in conjunction with the accompanying drawings, including various details of the embodiments of the present invention to aid understanding. These should be considered merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.
[0043] Where there is no conflict, the various embodiments of the present invention and the features thereof may be combined with each other.
[0044] As used herein, the term “and / or” includes any and all combinations of one or more related enumerated entries.
[0045] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms “a” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising” and / or “made of” are used in this specification, the presence of the stated feature, integral, step, operation, element, and / or component is specified, but the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof is not excluded. Terms such as “connected” or “linked” are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect.
[0046] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having the meaning consistent with their meaning in the context of the relevant art and the invention, and will not be interpreted as having an idealized or overly formal meaning unless expressly so defined herein.
[0047] In the technical solution of this invention, the collection, storage, use, processing, transmission, provision, and disclosure of user personal information all comply with relevant laws and regulations and do not violate public order and good morals. The use of user data in this technical solution follows relevant national laws and regulations (e.g., the "Information Security Technology - Personal Information Security Specification"). For example: appropriate measures are taken for personal information access control; restrictions are imposed on the display of personal information; the purpose of using personal information does not exceed the scope of direct or reasonable association; and explicit identity targeting is eliminated when using personal information to avoid precisely locating a specific individual.
[0048] In related technologies, a vehicle downhill control method is disclosed. This method calculates the total braking force required for the vehicle to descend a slope at a set speed. It compares the maximum electric braking force provided by the motor with the total braking force. When the maximum electric braking force provided by the motor is greater than or equal to the total braking force, the motor is controlled to apply electric braking using the total braking force. When the maximum electric braking force provided by the motor is less than the total braking force, the motor is controlled to apply electric braking using the maximum electric braking force, and the air brake controller is controlled to apply air braking to compensate for the electric braking. However, this scheme prioritizes electric braking and does not consider the problem that on low-friction slopes, the large absolute value of the negative torque from electric braking can easily cause wheel lock-up.
[0049] In related technologies, a cruise braking method for vehicles is also disclosed, which activates the vehicle's auxiliary braking or main braking and maintains cruise mode when it is determined that the vehicle is in a downhill speeding state. However, this solution mainly relies on mechanical braking to maintain cruise mode when it is determined that the vehicle is in a downhill speeding state. On the one hand, it does not fully incorporate electric braking to improve range; on the other hand, for long slopes, prolonged and large mechanical braking can easily cause the braking system to overheat, reducing braking effectiveness.
[0050] To address at least one of the technical problems existing in the aforementioned related technologies, the present invention provides a method and system for controlling the slow-moving behavior of electric vehicles on downhill slopes.
[0051] This invention discloses a method for controlling downhill driving of electric vehicles, such as... Figure 1 ,include:
[0052] S100. Obtain real-time vehicle status parameters and calculate the total target braking torque for downhill descent; in this embodiment, the specific method for calculating the total target braking torque for downhill descent includes: obtaining the tangential component torque of gravity T. G and speed control correction torque T v， The total target braking torque for slow downhill driving was calculated. , .
[0053] Among them, the speed control correction torque T v The acquisition method includes: obtaining the current downhill gradient value; looking up a table based on the current gradient value to obtain a target vehicle speed related to the gradient value; calculating the difference between the target vehicle speed and the actual vehicle speed to obtain the speed control deviation; and obtaining the speed control correction torque based on the speed control deviation through PI control. .
[0054] Specifically, the downhill driving described in this embodiment not only includes downhill cruise control that requires a fixed speed, but also includes off-road downhill scenarios where a certain towing force needs to be applied to the vehicle to prevent it from abnormally climbing the slope. In downhill cruise control with a fixed speed, the target speed is a set, fixed value. In off-road downhill scenarios, the speed does not need to be completely fixed; a desired dynamic target speed related to the slope can be obtained by looking up a preset table based on the current slope value. The difference between the target speed and the actual speed yields the speed control deviation. Based on the speed control deviation, a speed control correction torque can be obtained through PI control. . The design already includes compensation for air resistance.
[0055] Total target braking torque ( (negative values) can be obtained through the tangential component of gravity torque. and PI-based speed control to correct torque Together we get:
[0056]
[0057] For example, PI-based speed control corrects torque. The torque component of gravity is 200 Nm. If the value is 3000 Nm, then the target braking torque is If torque is corrected based on PI speed control -200 Nm, gravitational component torque If the value is 3000 Nm, then the target braking torque is .
[0058] S200. Based on the principle of prioritizing electric braking, and combining the battery recovery capacity and the minimum negative torque capacity of the motor, the minimum electric braking capacity boundary is determined; according to the total target braking torque and the minimum capacity boundary, the basic electric braking negative torque and the basic mechanical braking torque are allocated.
[0059] Specifically, from the perspective of improving the vehicle's overall range, when vehicle stability is good, electric braking negative torque should be used as much as possible first. This is also the basis for the basic distribution of electric braking negative torque and basic mechanical braking torque to the target braking torque.
[0060] The vehicle control unit (VCU) needs to calculate the minimum electric braking capability boundary TMc (TMc is a negative value) by combining the battery's current allowable regeneration capacity and the motor's minimum negative torque capacity.
[0061] In this embodiment, based on the total target braking torque and the minimum capacity boundary, the basic electric braking negative torque and the basic mechanical braking torque are allocated, specifically including:
[0062] When the target braking torque Minimum capability boundary At this time, the target braking torque is entirely borne by the electric brake, and the mechanical brake does not work; therefore, the basic electric brake has a negative torque. = Mechanical braking torque = 0Nm;
[0063] When the target braking torque Minimum capability boundary At that time, the electric brake operates at maximum capacity. The output is supplemented by mechanical braking if insufficient; therefore, the basic electric braking negative torque is... Basic mechanical braking torque .
[0064] In this embodiment, the control system will be configured, including the basic electric braking negative torque. ≤0 Nm, basic mechanical braking torque ≥0Nm.
[0065] S300. Collect the wheel speeds of the four wheels and calculate the vehicle's current maximum slip ratio; when the vehicle is traveling on a slope with a low coefficient of adhesion, a large absolute value of electric braking negative torque may cause the wheels to lock up.
[0066] Therefore, it is necessary to first identify the maximum slip ratio of the entire vehicle to provide a basis for further correction of the electric braking negative torque and mechanical braking torque.
[0067] In this embodiment, the formula for calculating the vehicle's current maximum slip ratio is:
[0068]
[0069] in, For reference speed, Let be the minimum wheel speed of the four wheels; where:
[0070]
[0071] in, The left front wheel, The right front wheel, It is the left rear wheel. It is the right rear wheel.
[0072] In this embodiment, the vehicle's slip ratio is introduced, which can dynamically monitor the situation when the wheels tend to lock up and transfer a portion of the electric braking negative torque to mechanical braking torque in advance. This ensures that the vehicle's range is maximized while avoiding wheel lock-up.
[0073] S400. Calculate the electric braking correction torque based on the maximum slip ratio; In this embodiment, the method for calculating the electric braking correction torque based on the maximum slip ratio includes:
[0074] When the maximum slip ratio exceeds the preset slip ratio threshold and exceeds the preset time, the vehicle controller activates closed-loop control of the slip ratio; the slip ratio deviation is calculated. , ; For the maximum slip ratio, To achieve a target slip ratio that improves vehicle stability, PID closed-loop control is implemented based on the slip ratio deviation Δλ to obtain the electric braking correction torque. .
[0075] Specifically, when the maximum slip ratio It is greater than the set slip ratio threshold. Furthermore, when a certain time t is reached, it is assumed that the wheels are on the low-friction surface and have a tendency to lock up, and the vehicle control unit (VCU) activates the closed-loop control of the slip ratio.
[0076] Set a target slip ratio that provides good vehicle stability The slip ratio deviation is:
[0077]
[0078] Based on slip ratio deviation PID closed-loop control is performed to obtain the corrected torque for the basic electric braking negative torque. The corrective torque should reduce the absolute value of the base electric braking negative torque, therefore: ≥0Nm.
[0079] S500. Calculate the target electric braking negative torque and the target mechanical braking torque based on the electric braking correction torque. In this embodiment, the specific method for calculating the target electric braking negative torque and the target mechanical braking torque based on the electric braking correction torque includes:
[0080] Target electric braking negative torque Equal to the basic electric braking negative torque Add corrected torque ,Right now
[0081] Target electric braking negative torque Target mechanical braking torque Equal to the basic mechanical braking torque Add corrected torque That is, the target mechanical braking torque The target electric braking negative torque and the target mechanical braking torque are respectively sent to the motor controller and the braking control system for execution.
[0082] Specifically, the target electric braking negative torque It should be equal to the basic electric braking negative torque. Add corrected torque To reduce the basic electric braking negative torque The absolute value of the target mechanical braking torque. It should be equal to the basic mechanical braking torque. Add corrected torque To increase the basic mechanical braking torque The absolute value of . That is:
[0083] Target electric braking negative torque
[0084] Target mechanical braking torque
[0085] In this embodiment, the control system is set to: target electric braking negative torque. Target mechanical braking torque .
[0086] This embodiment discloses a downhill descent control method for electric vehicles. The method includes: acquiring real-time vehicle status parameters and calculating the total target braking torque for downhill descent; determining the minimum electric braking capacity boundary based on the principle of prioritizing electric braking, combined with battery recovery capability and the minimum negative torque capability of the motor; allocating a basic electric braking negative torque and a basic mechanical braking torque according to the total target braking torque and the minimum capacity boundary; collecting the wheel speeds of the four wheels and calculating the vehicle's current maximum slip ratio; calculating the electric braking correction torque based on the maximum slip ratio; and calculating the target electric braking negative torque and the target mechanical braking torque based on the electric braking correction torque. This invention effectively avoids wheel lock-up on low-adhesion surfaces due to large absolute values of electric braking negative torque, while prioritizing energy recovery and range capability. This improves downhill driving stability and safety, and is applicable to downhill cruise control and off-road downhill scenarios for pure electric and hybrid vehicles equipped with both electric and mechanical braking.
[0087] Based on the same inventive concept, embodiments of the present invention also provide an electric vehicle downhill easing control system, such as... Figure 2 It includes: a total target braking torque calculation unit, a basic electric braking negative torque and basic mechanical braking torque calculation unit, a maximum slip ratio calculation unit, an electric braking correction torque calculation unit, and a target electric braking negative torque and target mechanical braking torque calculation unit; wherein:
[0088] The total target braking torque calculation unit is used to acquire real-time vehicle status parameters and calculate the total target braking torque for slow downhill driving.
[0089] The basic electric braking negative torque and basic mechanical braking torque calculation unit is used to determine the minimum electric braking capacity boundary based on the principle of electric braking priority, combined with the battery recovery capacity and the minimum negative torque capacity of the motor; and to allocate the basic electric braking negative torque and basic mechanical braking torque according to the total target braking torque and the minimum capacity boundary.
[0090] The maximum slip ratio calculation unit is used to collect the wheel speeds of the four wheels and calculate the vehicle's current maximum slip ratio.
[0091] An electric braking correction torque calculation unit is used to calculate the electric braking correction torque based on the maximum slip ratio;
[0092] The target electric braking negative torque and target mechanical braking torque calculation unit is used to calculate the target electric braking negative torque and target mechanical braking torque based on the electric braking correction torque.
[0093] The specific working methods of the total target braking torque calculation unit, the basic electric braking negative torque and basic mechanical braking torque calculation unit, the maximum slip ratio calculation unit, the electric braking correction torque calculation unit, and the target electric braking negative torque and target mechanical braking torque calculation unit have been described in detail in the above methods, and will not be repeated here in this embodiment.
[0094] Based on the same inventive concept, embodiments of the present invention also provide an electronic device. Figure 3 This is a structural block diagram of an electronic device provided in an embodiment of the present invention. Figure 3 As shown, an embodiment of the present invention provides an electronic device including: one or more processors 101, a memory 102, and one or more I / O interfaces 103. The memory 102 stores one or more programs, which, when executed by the one or more processors, cause the one or more processors to implement any of the control methods described in the above embodiments; the one or more I / O interfaces 103 are connected between the processor and the memory, configured to enable information interaction between the processor and the memory.
[0095] The processor 101 is a device with data processing capabilities, including but not limited to a central processing unit (CPU); the memory 102 is a device with data storage capabilities, including but not limited to random access memory (RAM, more specifically SDRAM, DDR, etc.), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), and flash memory (FLASH); the I / O interface (read / write interface) 103 is connected between the processor 101 and the memory 102, and can realize information interaction between the processor 101 and the memory 102, including but not limited to a data bus (Bus).
[0096] In some embodiments, the processor 101, memory 102, and I / O interface 103 are interconnected via bus 104, and thus connected to other components of the computing device.
[0097] In some embodiments, the one or more processors 101 include a field-programmable gate array.
[0098] This invention also provides a computer-readable medium. The computer-readable medium stores a computer program, which, when executed by a processor, implements the steps of any of the control methods described in the above embodiments. The computer-readable storage medium may be volatile or non-volatile.
[0099] This invention also provides a computer program product, including computer-readable code, or a non-volatile computer-readable storage medium carrying computer-readable code. When the computer-readable code is run in the processor of an electronic device, the processor in the electronic device executes the above-described control method.
[0100] Those skilled in the art will understand that all or some of the steps, systems, and apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit (ASIC). Such software can be distributed on a computer-readable storage medium, which may include computer storage media (or non-transitory media) and communication media (or transient media).
[0101] As is known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information, such as computer-readable program instructions, data structures, program modules, or other data. Computer storage media includes, but is not limited to, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), static random access memory (SRAM), flash memory or other memory technologies, portable compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, it is known to those skilled in the art that communication media typically contain computer-readable program instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.
[0102] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.
[0103] The computer program instructions used to perform the operations of this invention may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages such as Smalltalk, C++, etc., and conventional procedural programming languages such as the "C" language or similar programming languages. The computer-readable program instructions may be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing state information from the computer-readable program instructions. This electronic circuitry can execute the computer-readable program instructions to implement various aspects of the invention.
[0104] The computer program product described herein can be implemented specifically through hardware, software, or a combination thereof. In one alternative embodiment, the computer program product is specifically embodied in a computer storage medium; in another alternative embodiment, the computer program product is specifically embodied in a software product, such as a software development kit (SDK), etc.
[0105] Various aspects of the present invention are described herein with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should 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-readable program instructions.
[0106] These computer-readable program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that, when executed by the processor of the computer or other programmable data processing apparatus, they create means for implementing the functions / actions specified in one or more blocks of the flowchart and / or block diagram. These computer-readable program instructions can also be stored in a computer-readable storage medium that causes a computer, programmable data processing apparatus, and / or other device to operate in a particular manner; thus, the computer-readable medium storing the instructions comprises an article of manufacture that includes instructions for implementing aspects of the functions / actions specified in one or more blocks of the flowchart and / or block diagram.
[0107] Computer-readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable data processing apparatus, or other device to produce a computer-implemented process, thereby causing the instructions executed on the computer, other programmable data processing apparatus, or other device to perform the functions / actions specified in one or more boxes of a flowchart and / or block diagram.
[0108] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of an instruction, which contains one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than those shown in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.
[0109] Example embodiments have been disclosed herein, and while specific terminology has been used, it is for illustrative purposes only and should be construed as such, and is not intended to be limiting. In some instances, it will be apparent to those skilled in the art that features, characteristics, and / or elements described in conjunction with particular embodiments may be used alone, or in combination with features, characteristics, and / or elements described in conjunction with other embodiments, unless otherwise expressly indicated. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of the invention as set forth in the appended claims.
Claims
1. A method for controlling downhill descent of an electric vehicle, characterized in that, include: Obtain real-time vehicle status parameters and calculate the total target braking torque for slow downhill driving. Based on the principle of prioritizing electric braking, and combining the battery recovery capacity and the minimum negative torque capacity of the motor, the minimum electric braking capacity boundary is determined. Based on the total target braking torque and the minimum capacity boundary, the basic electric braking negative torque and the basic mechanical braking torque are allocated; Collect the wheel speeds of the four wheels and calculate the vehicle's current maximum slip ratio; Calculate the electric braking correction torque based on the maximum slip ratio; The target electric braking negative torque and the target mechanical braking torque are calculated based on the electric braking correction torque.
2. The control method according to claim 1, characterized in that, The method for calculating the total target braking torque for slow-moving downhill driving includes: obtaining the tangential component torque T of gravity. G and speed control correction torque T v， The total target braking torque for slow downhill driving was calculated. , .
3. The control method according to claim 2, characterized in that, Speed control correction torque T v The acquisition method includes: obtaining the current downhill gradient value; looking up a table based on the current gradient value to obtain a target vehicle speed related to the gradient value; calculating the difference between the target vehicle speed and the actual vehicle speed to obtain the speed control deviation; and obtaining the speed control correction torque based on the speed control deviation through PI control. .
4. The control method according to claim 1, characterized in that, Based on the total target braking torque and the minimum capacity boundary, the basic electric braking negative torque and the basic mechanical braking torque are allocated, specifically including: When the target braking torque Minimum capability boundary At this time, the target braking torque is entirely borne by the electric brake, and the mechanical brake does not work; therefore, the basic electric brake has a negative torque. = Mechanical braking torque = 0Nm; When the target braking torque Minimum capability boundary At that time, the electric brake operates at maximum capacity. The output is supplemented by mechanical braking if insufficient; therefore, the basic electric braking negative torque is... Basic mechanical braking torque .
5. The control method according to claim 4, characterized in that, Basic electric braking negative torque Basic mechanical braking torque The total braking torque remains unchanged.
6. The control method according to claim 1, characterized in that, The formula for calculating the vehicle's current maximum slip ratio is: ； in, For reference speed, Let be the minimum wheel speed of the four wheels; where: ； in, The left front wheel, The right front wheel, It is the left rear wheel. It is the right rear wheel.
7. The control method according to claim 1, characterized in that, The method for calculating the electric braking correction torque based on the maximum slip ratio includes: When the maximum slip ratio exceeds the preset slip ratio threshold and exceeds the preset time, the vehicle controller activates closed-loop control of the slip ratio; the slip ratio deviation is calculated. , ; For the maximum slip ratio, To achieve a target slip ratio that improves vehicle stability, PID closed-loop control is implemented based on the slip ratio deviation Δλ to obtain the electric braking correction torque. .
8. The control method according to claim 1, characterized in that, The target electric braking negative torque and the target mechanical braking torque are calculated based on the electric braking correction torque. Specific methods include: Target electric braking negative torque Equal to the basic electric braking negative torque Add corrected torque ,Right now Target electric braking negative torque Target mechanical braking torque Equal to the basic mechanical braking torque Add corrected torque That is, the target mechanical braking torque The target electric braking negative torque and the target mechanical braking torque are respectively sent to the motor controller and the braking control system for execution.
9. A downhill easing control system for an electric vehicle, employing any one of the control methods described in claims 1-8, characterized in that, include: The system includes: a total target braking torque calculation unit, a basic electric braking negative torque and basic mechanical braking torque calculation unit, a maximum slip ratio calculation unit, an electric braking correction torque calculation unit, and a target electric braking negative torque and target mechanical braking torque calculation unit; among which: The total target braking torque calculation unit is used to acquire real-time vehicle status parameters and calculate the total target braking torque for slow downhill driving. The basic electric braking negative torque and basic mechanical braking torque calculation unit is used to determine the minimum electric braking capacity boundary based on the principle of electric braking priority, combined with the battery recovery capacity and the minimum negative torque capacity of the motor; and to allocate the basic electric braking negative torque and basic mechanical braking torque according to the total target braking torque and the minimum capacity boundary. The maximum slip ratio calculation unit is used to collect the wheel speeds of the four wheels and calculate the vehicle's current maximum slip ratio. An electric braking correction torque calculation unit is used to calculate the electric braking correction torque based on the maximum slip ratio; The target electric braking negative torque and target mechanical braking torque calculation unit is used to calculate the target electric braking negative torque and target mechanical braking torque based on the electric braking correction torque.
10. An electronic device, characterized in that, include: One or more processors; Memory, used to store one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the control method as described in any one of claims 1 to 8.