Pure electric vehicle torque management control method

Abstract

This invention discloses a torque management and control method for pure electric vehicles. The main design concept of this invention lies in activating torque arbitration and torque distribution functions after the torque management function is enabled. The torque arbitration requires torque including: drive torque, intelligent torque, and energy recovery torque. Based on the arbitration result, the vehicle function corresponding to the current torque demand type is determined. According to the determined torque demand type after arbitration, combined with the vehicle's currently selected road mode and / or driving mode, the drive torque distribution ratio or the energy recovery torque distribution ratio between the front and rear axles is set or dynamically adjusted. This invention makes reasonable decisions regarding the torque demand of pure electric vehicles and utilizes the decision results, combined with driving and road modes, to achieve a more comprehensive and detailed front-to-rear axle torque ratio, providing an effective solution for the pure electric vehicle field.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle technology, and in particular to a torque management and control method for pure electric vehicles. Background Technology

[0002] Electric vehicle powertrain systems should be able to achieve stable driving functions. This means the powertrain system should analyze input devices such as accelerator pedal position, brake pedal position, and gear position to determine the required driving force under any driving condition, thus meeting the driver's power (torque) requirements for vehicle propulsion. In addition to the most basic driving torque management capabilities (including accelerator pedal torque, creep torque, pre-torque, and zero torque), modern vehicles must also meet other intelligent and efficient torque requirements. These requirements include intelligent torque demand (such as adaptive cruise control (ACC) and automatic parking assist (APA), vehicle stability torque demand (integrated braking system IBS related functions), and energy recovery torque demand (coasting energy recovery and braking energy recovery). The vehicle needs to control and manage the entire torque path.

[0003] The torque path of a vehicle, from torque request to final torque execution, involves multiple stages such as torque limiting, torque arbitration, torque distribution, torque processing, stability torque intervention, and active damping control. Furthermore, torque control requires the coordinated control of numerous control units, including the vehicle control unit (VDC), integrated braking system (IBS), motor controller (MCUR, MCUF), and battery management system (BMS).

[0004] Currently, there is still considerable room for optimization and improvement in the industry's torque request arbitration and torque distribution schemes for pure electric vehicles, including the entry conditions and functional requirement definitions involved. Summary of the Invention

[0005] In view of the above, the present invention aims to provide a torque management and control method for pure electric vehicles to solve the aforementioned technical problems.

[0006] The technical solution adopted in this invention is as follows:

[0007] This invention provides a torque management and control method for pure electric vehicles, comprising:

[0008] After the torque management function is enabled, the torque arbitration function and torque distribution function are enabled: the torque arbitration demand torque includes: drive demand torque, intelligent demand torque, and energy recovery demand torque.

[0009] Based on the arbitration results, determine the vehicle function corresponding to the current torque demand type;

[0010] Based on the required torque type determined after arbitration, and in conjunction with the vehicle's currently selected road mode and / or driving mode, the drive torque distribution ratio between the front and rear axles or the regenerative torque distribution ratio between the front and rear axles is set or dynamically adjusted.

[0011] In at least one of the possible implementations, the arbitration process includes: determining the current torque demand type and its corresponding function based on the magnitude of the torque demand within the same type.

[0012] In at least one of the possible implementations, the arbitration process further includes: arbitrating multiple torque demand types, and making decisions according to the following priority: brake energy recovery function torque request > intelligent torque demand > coasting energy recovery function torque request > drive torque demand.

[0013] In at least one of the possible implementations, if the arbitration result is the required driving torque, the method for setting the driving torque distribution ratio between the front axle and the rear axle includes:

[0014] When the vehicle is in preset snow mode, normal driving mode, sport mode, or road mode, the drive torque distribution ratio between the front axle and the rear axle is set based on the distance from the front axle and the rear axle to the vehicle's center of gravity, the vehicle speed, and the acceleration.

[0015] In at least one of the possible implementations, if the arbitration result is the required driving torque, the methods for dynamically adjusting the driving torque distribution ratio between the front axle and the rear axle include:

[0016] Based on the steering wheel angle and vehicle longitudinal acceleration, if an increase in the rate of change of accelerator pedal opening is detected, the drive torque distribution ratio will be reduced; and / or, depending on the tire slippage state, a portion of the torque of the axle corresponding to the slipping tire will be transferred to another axle; and / or, if the torque request of the front or rear motor is limited, the excess torque will be transferred to another axle.

[0017] In at least one of the possible implementations, if the arbitration result is the energy recovery torque requirement, the method for setting the recovery torque distribution ratio between the front axle and the rear axle includes:

[0018] When the vehicle is in the preset normal driving mode or sport mode, the regenerative torque distribution ratio between the front axle and the rear axle is directly set to 50:50.

[0019] When the vehicle is in the preset road mode, the recovery torque distribution ratio is set based on the distances from the front axle and the rear axle to the vehicle's center of gravity, or the recovery torque distribution ratio is directly set to 50:50.

[0020] Compared with existing technologies, the main design concept of this invention lies in activating torque arbitration and torque distribution functions after the torque management function is enabled. The torque arbitration requires torques including drive torque, intelligent torque, and energy recovery torque. Based on the arbitration result, the vehicle function corresponding to the current torque demand type is determined. According to the determined torque demand type after arbitration, combined with the vehicle's currently selected road mode and / or driving mode, the drive torque distribution ratio or the energy recovery torque distribution ratio between the front and rear axles is set or dynamically adjusted. This invention makes reasonable decisions regarding the torque demand of pure electric vehicles and utilizes the decision results, combined with driving and road modes, to achieve a more comprehensive and detailed front-to-rear axle torque ratio, providing an effective solution for the pure electric vehicle field. Attached Figure Description

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below with reference to the accompanying drawings, wherein:

[0022] Figure 1 This is a flowchart illustrating the torque management and control method for pure electric vehicles provided in an embodiment of the present invention. Detailed Implementation

[0023] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0024] This invention proposes an embodiment of a torque management control method for pure electric vehicles, specifically, as follows: Figure 1 As shown, it includes:

[0025] Step S1: After the torque management function is enabled, enable the torque arbitration function and the torque distribution function:

[0026] In the torque arbitration process, the required torque can be broadly categorized into three types:

[0027] The first category is driving torque demand, including: accelerator pedal torque, creeping torque, pre-torque, and zero torque;

[0028] Accelerator pedal torque: Based on the accelerator pedal, vehicle speed, SOC, etc., the reasonable vehicle torque requirement is analyzed according to the Pedal map (referred to as the accelerator pedal characteristic map in this invention, specifically the target torque output of the power system under different accelerations and vehicle speeds, which is pre-calibrated to obtain the corresponding relationship between acceleration input and power output).

[0029] Creep torque: The driving torque during the process of the vehicle being in driving gear (D / R), the brake pedal being released, and the accelerator pedal not being pressed.

[0030] Pre-torque (creep function): After the vehicle starts, when the vehicle is stationary or traveling at low speed (low speed threshold can be preset), in order to prevent the vehicle from shaking due to motor gear backlash, the VCU requests a smaller torque based on the current gear to eliminate gear backlash.

[0031] The second category is intelligent demand torque, including: for example, the torque for adaptive cruise control (ACC), traffic jam assist (TJA), highway cruise assist (HWA), cruise control assist (NCA), fully automatic parking system (APS), and fully automatic vehicle departure function torque, etc.

[0032] The third category is energy recovery demand torque, including: coasting energy recovery function torque and braking energy recovery function torque.

[0033] Step S2: Based on the arbitration result, determine the vehicle function corresponding to the current required torque type;

[0034] During the arbitration process, the current torque demand type and its corresponding function can be determined based on the magnitude of the torque demand within the same type. For example, for the type of drive torque demand, when the vehicle control unit (VDC) only recognizes that both the parsed vehicle drive torque request and creep torque request flags are valid, the VDC calculates based on the driving mode, accelerator pedal position, current vehicle speed, and current drive torque, and the arbitration result is to execute the function corresponding to the one with the larger torque demand. Furthermore, it can be understood that when zero torque request and creep function are activated simultaneously, the arbitration result is creep function.

[0035] In another embodiment, when the vehicle is in autonomous driving mode, i.e., when there is intelligent torque demand, after receiving an electric drive torque request (accelerator pedal depressed but brake pedal not depressed, i.e., drive torque demand similar to the type of drive torque demand), if the calculated electric drive torque request is greater than the torque requested by the autonomous driving function, then the arbitration is to activate the overtake mode and respond to the electric drive torque request; furthermore, if in autonomous driving mode, it is detected that the user has depressed the pedal for more than 1 minute (Time_DriverTakeOver, TBD), then it is determined that the user intends to take over the driving operation, and then the autonomous driving related functions are turned off.

[0036] Of course, the above is only an illustrative explanation of several situations. If multiple torque demands meet the entry conditions at the same time, arbitration decisions need to be made according to the following priority: preset stability torque request > the aforementioned brake energy recovery function torque request > intelligent demand torque > coasting energy recovery function torque request > electric drive torque request (i.e., drive demand torque, more specifically, accelerator pedal torque).

[0037] Step S3: Based on the required torque type determined after arbitration, and in conjunction with the vehicle's currently selected road mode and / or driving mode, set or dynamically adjust the drive torque distribution ratio between the front axle and the rear axle, or the regenerative torque distribution ratio between the front axle and the rear axle.

[0038] It should be noted that two-wheel drive vehicles do not require torque distribution; therefore, this invention only proposes a front-to-rear axle torque distribution scheme for four-wheel drive vehicles. That is, when the target vehicle is a four-wheel drive vehicle, torque can be distributed according to the following requirements: Furthermore, the main principle in torque distribution is that, based on different road conditions and established driving modes, and with the goals of economy, power, and drivability, initial torque distribution (setting) and subsequent distribution optimization (adjustment) are performed for the driving torque distribution or regenerative torque distribution of the four-wheel drive vehicle.

[0039] For example, if the arbitration result is the required torque for driving, the following torque distribution example is provided for reference:

[0040] (1) When the vehicle is in snow mode, in order to make full use of the ground adhesion, the drive torque distribution ratio β between the front axle and the rear axle can be set based on factors such as the distance from the front axle and the rear axle to the center of gravity of the vehicle, the vehicle speed and acceleration.

[0041] (2) When the vehicle is in the economy mode (ECO), based on the efficiency mapping (MAP) relationship between the front motor and the rear motor, the goal of the drive torque distribution is to achieve the best economy (energy saving and minimum energy consumption). For example, if the drive efficiency of the rear motor is significantly higher than that of the front motor at a lower torque and lower speed, then β = 0:100.

[0042] (3) In normal mode (NOM), when the accelerator pedal depth exceeds a predetermined threshold, such as 40% (TrpDist_NOMPedalLim), in order to achieve the best driving performance and make full use of the ground adhesion, the front and rear axle drive torque distribution ratio β can be set based on factors such as the distance from the front and rear axles to the vehicle's center of gravity, vehicle speed, and acceleration; if the accelerator pedal depth does not exceed the predetermined threshold, the distribution is carried out according to the principle of optimal economy.

[0043] (4) In Sport mode (SPT), in order to achieve the best driving performance and make full use of the ground adhesion, the front and rear axle drive torque distribution ratio β can be set based on factors such as the distance from the front and rear axles to the vehicle's center of gravity, vehicle speed, and acceleration.

[0044] (5) In road mode, in order to achieve the best driving performance and make full use of ground adhesion, the front and rear axle drive torque distribution ratio β can be set based on factors such as the distance from the front and rear axles to the vehicle center of gravity, vehicle speed and acceleration.

[0045] Furthermore, in the torque distribution stage, the vehicle control unit (VDC) can combine the steering wheel angle and vehicle longitudinal acceleration (based on the integrated braking system IBS signal, which is related to the slope and the actual vehicle acceleration). If the rate of change of accelerator pedal opening (monotonically increasing) increases, more drive torque needs to be distributed to the rear motor, i.e., β is smaller; and / or, based on the slippage of the front and rear tires, it is necessary to transfer part of the torque of the axle corresponding to the slipping tire to another axle (if any front wheel has slippage characteristics, then part of the torque of the front axle is dynamically added to the rear axle); and / or, the torque limits of the front and rear axles can also be considered. If the torque request of a certain motor is limited (torque limiting control), then the torque exceeding the limit is transferred to another axle.

[0046] Following on from the previous text, regarding the arbitration result of the energy recovery demand torque, which is the torque required to execute the energy recovery function (including the aforementioned coasting energy recovery function torque and braking energy recovery function torque), the following torque allocation example is provided for reference:

[0047] (1) When the vehicle is in road mode, in order to make full use of the ground adhesion, the regenerative torque distribution ratio γ between the front and rear axles is mainly set based on the distance from the front axle and the rear axle to the center of gravity of the vehicle, or it can be directly set to γ ​​= 50:50 (TBD).

[0048] (2) When the vehicle is in ECO mode, as mentioned above, for example, when the rear motor has a very high feedback efficiency at a low torque and low speed, while the front motor has a very low feedback efficiency, then γ = 0:100.

[0049] (3) In NOM and SPT modes, the target is γ = 50:50 (TBD) to achieve the best driving performance and braking stability.

[0050] In summary, the main design concept of this invention lies in activating the torque arbitration and torque distribution functions after the torque management function is enabled. The torque arbitration requires torques including drive torque, intelligent torque, and energy recovery torque. Based on the arbitration result, the vehicle function corresponding to the current torque demand type is determined. According to the determined torque demand type after arbitration, combined with the vehicle's currently selected road mode and / or driving mode, the drive torque distribution ratio or the energy recovery torque distribution ratio between the front and rear axles is set or dynamically adjusted. This invention makes reasonable decisions regarding the torque demand of pure electric vehicles and utilizes the decision results, combined with driving and road modes, to achieve a more comprehensive and detailed front-to-rear axle torque ratio, providing an effective solution for the pure electric vehicle field.

[0051] In this invention, when directional terms are mentioned, they are relative concepts based on the embodiments. Furthermore, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent the existence of A alone, A and B simultaneously, or B alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, and c can represent: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, and c can be single or multiple.

[0052] The above description of the structure, features, and effects of the present invention is based on the embodiments shown in the figures. However, the above are only preferred embodiments of the present invention. It should be noted that the technical features involved in the above embodiments and their preferred methods can be reasonably combined and matched by those skilled in the art to form a variety of equivalent solutions without departing from or changing the design concept and technical effects of the present invention. Therefore, the present invention is not limited to the scope of implementation shown in the figures. Any changes made in accordance with the concept of the present invention, or modifications to equivalent embodiments, that do not exceed the spirit covered by the specification and figures, should be within the protection scope of the present invention.

Claims

1. A torque management and control method for a pure electric vehicle, characterized in that, include: After the torque management function is enabled, the torque arbitration function and torque distribution function are enabled: the torque arbitration requirement torque includes: drive torque requirement torque and energy recovery torque requirement torque. Based on the arbitration results, determine the current torque demand type and its corresponding vehicle function; Based on the required torque type determined after arbitration, and in conjunction with the vehicle's currently selected road mode and / or driving mode, the drive torque distribution ratio between the front axle and the rear axle or the regenerative torque distribution ratio between the front axle and the rear axle are set. Specifically, if the arbitration result is the required driving torque, the method for setting the driving torque distribution ratio between the front and rear axles includes: When the vehicle is in snow mode, the drive torque distribution ratio between the front axle and the rear axle is set based at least on the distance from the front axle and the rear axle to the vehicle's center of gravity, the vehicle speed, and the acceleration. When the vehicle is in economy mode, the optimal economy is achieved as the target for drive torque distribution based on the efficiency mapping relationship between the front motor and the rear motor. When the vehicle is in normal driving mode, if the accelerator pedal depth does not exceed a predetermined threshold, torque distribution is performed according to the principle of optimal economy, where optimal economy refers to minimum energy consumption.

2. The torque management and control method for pure electric vehicles according to claim 1, characterized in that, The arbitration process includes: determining the current torque demand type and its corresponding function based on the magnitude of torque demand within the same type.

3. The torque management and control method for pure electric vehicles according to claim 2, characterized in that, The arbitration process also includes: arbitration for multiple torque demand types, with decisions made according to the following priority: brake energy recovery torque request > coasting energy recovery torque request > drive demand torque.

4. The torque management and control method for pure electric vehicles according to claim 1, characterized in that, If the arbitration result is the required driving torque, the methods for setting the driving torque distribution ratio between the front and rear axles also include: When the vehicle is in the preset normal driving mode, sport mode, or road mode, the drive torque distribution ratio between the front axle and the rear axle is set based on the distance from the front axle and the rear axle to the vehicle's center of gravity, the vehicle speed, and the acceleration.

5. The torque management and control method for pure electric vehicles according to claim 1, characterized in that, The control method further includes: dynamically adjusting the drive torque distribution ratio between the front axle and the rear axle or the regenerative torque distribution ratio between the front axle and the rear axle based on the required torque type determined after arbitration, combined with the vehicle's currently selected road mode and / or driving mode, specifically including: If the arbitration result is the required driving torque, the driving torque distribution ratio between the front and rear axles will be dynamically adjusted in the following ways: combining the steering wheel angle and the vehicle's longitudinal acceleration, if an increase in the rate of change of the accelerator pedal opening is detected, the driving torque distribution ratio will be reduced; and / or, based on the tire slippage state, a portion of the torque of the axle corresponding to the slipping tire will be transferred to another axle; and / or, if the torque request of the front or rear motor is limited, the torque exceeding the limit will be transferred to another axle.

6. The torque management and control method for pure electric vehicles according to any one of claims 1 to 5, characterized in that, If the arbitration result is the energy recovery torque requirement, the methods for setting the recovery torque distribution ratio between the front and rear axles include: When the vehicle is in the preset normal driving mode or sport mode, the regenerative torque distribution ratio between the front axle and the rear axle is directly set to 50:

50. When the vehicle is in the preset road mode, the recovery torque distribution ratio is set based on the distances from the front axle and the rear axle to the vehicle's center of gravity, or the recovery torque distribution ratio is directly set to 50:50.

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