A slope-assist parking strategy for an electric drive system based on brake pedal opening sensor

Abstract

The application discloses a kind of slope auxiliary parking strategies of electric drive system based on brake pedal opening sensor, it is characterized in that, the new energy vehicle should include electric drive system and vehicle controller, slope sensor, brake pedal sensor, its specific content includes, to achieve the purpose of liberating driver's feet and saving battery energy to prolong the endurance.The electric drive system in the application can fully combine different brake pedal opening and slope to carry out speed closed-loop adaptive adjustment, so as to realize the smooth parking of vehicle in slope.The technical scheme can improve the effective control of motor, save unnecessary battery energy consumption, reduce the development cost of whole vehicle.

Description

Technical Field

[0001] This invention mainly relates to the field of new energy vehicle technology, specifically to a hill-start assist parking strategy for an electric drive system based on a brake pedal opening sensor. Background Technology

[0002] With the continuous development of new energy vehicle technology, there has been considerable research in the field of hill-start assist for new energy vehicles. Many studies focus solely on the motor, proposing motor torque plus power control models and dual closed-loop control models for vehicle speed and current. These methods primarily focus on the motor's output characteristics and control strategies, but do not fully consider the impact on vehicle performance during hill-start assist. Other studies have proposed schemes using deviation-driven PI algorithms to control motor speed. This approach monitors the deviation between motor speed and current, dynamically adjusting motor control parameters to control vehicle performance during hill-start assist. However, these schemes do not consider how to conserve battery energy. Furthermore, several different hill-start assist systems have been designed to address the hill-start assist problem. These systems prevent rollback by adding braking force at the rear of the vehicle or employing other measures. However, the high design and implementation costs of these systems limit their widespread practical application. Summary of the Invention

[0003] 1. The technical problem that the invention aims to solve

[0004] This invention provides a hill-start assist parking strategy for an electric drive system based on a brake pedal opening sensor, which aims to free the driver's feet and save battery energy to extend the driving range. The electric drive system can fully combine different brake pedal openings and slopes to perform closed-loop adaptive speed adjustment, thereby enabling the vehicle to stop smoothly on a slope. At the same time, this technical solution can improve the effective control of the motor, save unnecessary battery energy consumption, and reduce the overall vehicle development cost.

[0005] 2. Technical Solution

[0006] To achieve the above objectives, this invention provides a hill-start assist parking strategy for an electric drive system based on a brake pedal opening sensor. The new energy vehicle should include an electric drive system, a vehicle controller, a hill sensor, and a brake pedal sensor. The specific steps are as follows:

[0007] S1: When a new energy vehicle is driving on a slope of varying gradient, the motor controller (MCU) and vehicle controller (VCU) in the electric drive system will periodically exchange CAN information via the CAN network. This exchange information includes information sent by the VCU such as the slope gradient (SP), brake pedal opening (PP), vehicle gear information, preload torque (PT), and zero speed flag; the information sent by the MCU includes speed, torque, and electric drive fault status.

[0008] S2: When a new energy vehicle is driving on a slope and the driver presses the brake pedal, the vehicle remains stationary on the slope. At this time, the VCU determines whether the vehicle meets the requirements for entering the hill-start assist parking function based on the vehicle status and the interaction information with the MCU. If it does, the VCU sends the corresponding preload target torque to the MCU based on the slope information obtained by the slope sensor.

[0009] S3: Subsequently, after receiving the zero-speed flag and vehicle gear information sent by the VCU, the MCU calculates the torque that the vehicle needs to balance on the slope based on the preload target torque sent by the VCU, as well as the brake pedal opening and slope information.

[0010] S4: After the driver releases the brake pedal, the electric drive system performs closed-loop adaptive speed adjustment on the slope based on the calculated output torque to ensure that the vehicle can brake and stop on the slope without the aid of other external forces.

[0011] Prior to step S3, the electric drive system establishes a calculation model for the vehicle's hill-start torque based on the brake pedal opening and related information on the preload target torque sent by the VCU and the brake pedal opening and slope information. The specific processing method is as follows:

[0012] S3-1: First, the vehicle's brake pedal opening position is divided into segments using four threshold values. Assuming the driver fully depresses the brake pedal to the value P, the four threshold values ​​for the brake pedal opening position are 25%P, 50%P, 75%P, and P. When the driver depresses the brake pedal to stop the vehicle on a slope, the MCU receives information from the VCU, including the zero-speed enable flag, preloaded torque PT, and brake pedal opening PP. The MCU then establishes different torque output calculation models based on different brake pedal openings.

[0013] S3-2: When the brake pedal opening received by the MCU is greater than 0 and less than or equal to 25%P, and the preload torque sent by the VCU is PT, the torque output force T calculation model established by the MCU based on the brake pedal opening in this interval is as follows:

[0014] T = t1 * PT (0.7 ≤ t1 < 0.8)

[0015] S3-3: When the brake pedal opening received by the MCU is greater than 25%P and less than or equal to 50%P, and the preload torque sent by the VCU is PT, the torque output force T calculation model established by the MCU based on the brake pedal opening in this interval is as follows:

[0016] T = t² * PT (0.8 ≤ t² < 0.9)

[0017] S3-4: When the brake pedal opening received by the MCU is greater than 50%P and less than or equal to 75%P, and the preload torque sent by the VCU is PT, the torque output force T calculation model established by the MCU based on the brake pedal opening in this interval is as follows:

[0018] T = t3 * PT (0.9 ≤ t3 < 1.0)

[0019] S3-4: When the brake pedal opening received by the MCU is greater than 75%P and less than or equal to P, and the preload torque sent by the VCU is PT, the torque output T calculation model established by the MCU based on the brake pedal opening in this interval is as follows:

[0020] T = t4 * PT (1.0 ≤ t4 < 1.1)

[0021] Preferably, in the slope parking torque calculation model based on brake pedal opening described in step 3, t1, t2, t3, and t4 can be determined by joint debugging and annotation according to different vehicle models during the actual vehicle testing phase.

[0022] 3. Beneficial effects

[0023] Compared with the prior art, the technical solution provided by this invention has the following advantages:

[0024] 1. This invention proposes a hill-start assist parking strategy for an electric drive system based on a brake pedal opening sensor. This strategy monitors the brake pedal opening in real time and automatically adjusts the motor control parameters according to the driver's operating intention and vehicle status to optimize the vehicle's hill-start parking performance and save battery energy consumption.

[0025] 2. This invention has high practical value and low cost, and helps to solve the problems and improve the existing slope parking control of new energy vehicles. Attached Figure Description

[0026] Figure 1 The flowchart illustrates a hill-start assist parking strategy for an electric drive system based on a brake pedal opening sensor, according to the present invention. Detailed Implementation

[0027] To facilitate understanding of the present invention, a more complete description of the invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the invention. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the invention will be more thorough and complete.

[0028] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "page," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] In this invention, unless otherwise explicitly specified and limited, the terms "installed," "connected," "linked," "fixed," and "equipped" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] Example

[0032] See attached document Figure 1 , Figure 1 This is a flowchart illustrating a hill-start assist parking strategy for an electric drive system based on a brake pedal opening sensor, as described in this invention. Figure 1 As shown, the electric drive system for hill-start assist parking based on the brake pedal opening sensor includes:

[0033] S1: When a new energy vehicle is driving on a slope of varying gradient, the motor controller (MCU) and vehicle controller (VCU) in the electric drive system will periodically exchange CAN information via the CAN network. This exchange information includes information sent by the VCU such as the slope gradient (SP), brake pedal opening (PP), vehicle gear information, preload torque (PT), and zero speed flag; the information sent by the MCU includes speed, torque, and electric drive fault status.

[0034] S2: When a new energy vehicle is driving on a slope and the driver presses the brake pedal, the vehicle remains stationary on the slope. At this time, the VCU determines whether the vehicle meets the requirements for entering the hill-start assist parking function based on the vehicle status and the interaction information with the MCU. If it does, the VCU sends the corresponding preload target torque to the MCU based on the slope information obtained by the slope sensor.

[0035] S3: Subsequently, after receiving the zero-speed flag and vehicle gear information sent by the VCU, the MCU calculates the torque that the vehicle needs to balance on the slope based on the preload target torque sent by the VCU, as well as the brake pedal opening and slope information.

[0036] S4: After the driver releases the brake pedal, the electric drive system performs closed-loop adaptive speed adjustment on the slope based on the calculated output torque to ensure that the vehicle can brake and stop on the slope without the aid of other external forces.

[0037] In step S3, a calculation model for the vehicle's hill-start torque based on the brake pedal opening is established according to the preload target torque sent by the electric drive system from the VCU, as well as information related to the brake pedal opening and the slope. The specific steps are as follows:

[0038] S3-1: First, the vehicle's brake pedal opening position is divided into segments using four threshold values. Assuming the driver fully depresses the brake pedal to the value P, the four threshold values ​​for the brake pedal opening position are 25%P, 50%P, 75%P, and P. When the driver depresses the brake pedal to stop the vehicle on a slope, the MCU receives information from the VCU, including the zero-speed enable flag, preloaded torque PT, and brake pedal opening PP. The MCU then establishes different torque output calculation models based on different brake pedal openings.

[0039] S3-2: When the brake pedal opening received by the MCU is greater than 0 and less than or equal to 25%P, and the preload torque sent by the VCU is PT, the torque output force T calculation model established by the MCU based on the brake pedal opening in this interval is as follows:

[0040] T = t1 * PT (0.7 ≤ t1 < 0.8)

[0041] S3-3: When the brake pedal opening received by the MCU is greater than 25%P and less than or equal to 50%P, and the preload torque sent by the VCU is PT, the torque output force T calculation model established by the MCU based on the brake pedal opening in this interval is as follows:

[0042] T = t² * PT (0.8 ≤ t² < 0.9)

[0043] S3-4: When the brake pedal opening received by the MCU is greater than 50%P and less than or equal to 75%P, and the preload torque sent by the VCU is PT, the torque output force T calculation model established by the MCU based on the brake pedal opening in this interval is as follows:

[0044] T = t3 * PT (0.9 ≤ t3 < 1.0)

[0045] S3-4: When the brake pedal opening received by the MCU is greater than 75%P and less than or equal to P, and the preload torque sent by the VCU is PT, the torque output T calculation model established by the MCU based on the brake pedal opening in this interval is as follows:

[0046] T = t4 * PT (1.0 ≤ t4 < 1.1)

[0047] The hill-start assist parking strategy of the electric drive system based on the brake pedal opening sensor described above is characterized in that t1, t2, t3, and t4 in the hill-start parking torque calculation model based on the brake pedal opening can be determined by joint debugging and annotation according to different vehicle models during the actual vehicle testing phase.

[0048] The above-described embodiments are merely illustrative of certain implementations of the present invention, and are described in a relatively specific and detailed manner. However, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A hill-start assist parking strategy for an electric drive system based on a brake pedal opening sensor, characterized in that, New energy vehicles include electric drive systems and vehicle controllers, hill-start sensors, and brake pedal sensors, specifically including: S1: When a new energy vehicle is driving on a slope of different gradients, the motor controller (MCU) and vehicle controller (VCU) in the electric drive system will periodically exchange CAN information through the CAN network. This exchange information includes the slope gradient (SP), brake pedal opening (PP), vehicle gear information, preload torque (PT), and zero speed flag, which are sent by the VCU; the information sent by the MCU includes speed, torque, and electric drive fault status. S2: When a new energy vehicle is driving on a slope and the driver presses the brake pedal, the vehicle remains stationary on the slope. At this time, the VCU determines whether the vehicle meets the requirements for entering the hill-start assist parking function based on the vehicle status and the interaction information with the MCU. If it does, the VCU sends the corresponding preload target torque to the MCU based on the slope information obtained by the slope sensor. S3: Subsequently, after receiving the zero-speed flag and vehicle gear information sent by the VCU, the MCU calculates the torque that the vehicle needs to balance on the slope based on the preload target torque sent by the VCU, as well as the brake pedal opening and slope information. In step S3, the electric drive system establishes a slope parking torque calculation model based on the brake pedal opening according to the preload target torque sent by the VCU and the relevant information on brake pedal opening and slope. The specific steps are as follows: S3-1: First, the vehicle's brake pedal opening position is divided into segments using four thresholds. Assuming the driver fully depresses the brake pedal to the opening degree P, the four thresholds for dividing the vehicle's brake pedal opening position are 25%P, 50%P, 75%P, and P. When the driver depresses the brake pedal to stop the vehicle on a slope, the MCU receives the zero-speed enable flag sent by the VCU, preloads the torque PT, and sets the brake pedal opening degree PP. The MCU will establish different torque output calculation models based on different brake pedal opening degrees. S3-2: When the brake pedal opening received by the MCU is greater than 0 and less than or equal to 25%P, and the preload torque sent by the VCU is PT, the torque output T calculation model established by the MCU based on the brake pedal opening in this interval is as follows: ； S3-3: When the brake pedal opening received by the MCU is greater than 25%P and less than or equal to 50%P, and the preload torque sent by the VCU is PT, the torque output force T calculation model established by the MCU based on the brake pedal opening in this interval is as follows: ； S3-4: When the brake pedal opening received by the MCU is greater than 50%P and less than or equal to 75%P, and the preload torque sent by the VCU is PT, the torque output T calculation model established by the MCU based on the brake pedal opening in this interval is as follows: ； S3-4: When the brake pedal opening received by the MCU is greater than 75%P and less than or equal to P, and the preload torque sent by the VCU is PT, the torque output force T calculation model established by the MCU based on the brake pedal opening in this interval is as follows: ； S4: After the driver releases the brake pedal, the electric drive system performs closed-loop adaptive speed adjustment on the slope based on the calculated output torque to ensure that the vehicle can brake and stop on the slope without the aid of other external forces.

2. The hill-start assist parking strategy for an electric drive system based on a brake pedal opening sensor according to claim 1, characterized in that... In the above-described slope parking torque calculation model based on brake pedal opening, The calibration can be determined during the actual vehicle testing phase based on different vehicle models.

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