A method and system for single-pedal torque control of electric vehicles

Abstract

This invention discloses a one-pedal torque control method for electric vehicles. In one-pedal driving mode: when the driver requests drive, the driving force is provided by the motor with positive torque; when the driver requests braking, negative torque is provided. When the driver releases the accelerator pedal to a specific opening and requests braking, the vehicle controller controls the output of negative torque to decelerate the vehicle based on the current vehicle state. This output negative torque is preferentially provided by the motor's energy recovery system. If the negative torque output by the motor's energy recovery system is unavailable or insufficient to meet the vehicle's braking torque requirements, the IPB brake controller performs hydraulic braking compensation, ensuring that the sum of the negative torque output by the motor's energy recovery system and the IPB hydraulic braking torque is close to or equal to the target braking torque required by the vehicle. In the one-pedal control process of this invention, motor braking and hydraulic braking are coordinated, and any degradation in one component is compensated by another, improving system robustness.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle technology, and in particular to a single-pedal torque control method for electric vehicles. Background Technology

[0002] With the increasing popularity of new energy electric vehicles, major automakers are paying more and more attention to the research and development of electric vehicles. Due to the energy-saving advantages of electric vehicles in regenerative braking, more and more people are dedicated to the development and research of torque control for electric vehicles. One-pedal throttle control, which can achieve vehicle acceleration, constant speed, and deceleration functions through a single throttle pedal, and can even stop the vehicle in special modes, not only improves energy recovery efficiency but also simplifies the driver's control, and is receiving increasing attention from major automakers.

[0003] One-pedal driving mode means that the driver can control the vehicle's starting, acceleration, deceleration, and stopping (optional) under normal operating conditions (following other vehicles on ordinary roads, parking on small slopes, etc.) by operating the accelerator pedal.

[0004] For example, the published document with announcement number CN115837844A, publication date March 24, 2023, and patent title "A Control Method for a Single-Pedal Electric Direct-Drive Vehicle," discloses a control method for a single-pedal electric direct-drive vehicle. This method first obtains the road slope, pedal displacement, and pedal displacement rate of the road where the vehicle is located. Then, it determines the operating range of the vehicle, which can be a driving range, a sliding range, or a braking range. When the vehicle is in the driving range, if the road slope is greater than 0, the torque value corresponding to the pedal opening is increased. Furthermore, if the road slope is greater than a slope threshold, the pedal displacement is greater than a pedal displacement threshold, or the pedal displacement rate threshold is greater than a pedal displacement rate threshold, compensation is required for the increased torque value corresponding to the pedal opening.

[0005] However, current electric vehicle one-pedal control methods suffer from reduced braking power after motor braking is downgraded during braking control. This affects the driver's control of the vehicle during one-pedal operation, making the brakes feel soft and causing the driver to lack "confidence". Summary of the Invention

[0006] The technical problem to be solved by the present invention is that the braking is weakened after the motor braking is downgraded, so as to realize a one-pedal torque control method and system for electric vehicles with smoother and safer operation.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a single-pedal torque control method for electric vehicles, in a single-pedal driving mode: when the driver requests to drive, the driving force is provided by the motor with positive torque; when the driver requests to brake, negative torque is provided. When the driver releases the accelerator pedal to a specific opening and requests to brake, the vehicle controller controls the output of negative torque to decelerate the vehicle according to the current vehicle state. The output negative torque is preferentially provided by the motor energy recovery. If the negative torque output by the motor energy recovery is withdrawn or cannot meet the vehicle's braking torque requirements, the IPB brake controller performs hydraulic braking compensation so that the sum of the negative torque output by the motor energy recovery and the IPB hydraulic braking torque is close to or equal to the target torque required by the vehicle's braking.

[0008] When the driver requests braking, braking control is performed based on vehicle speed information:

[0009] 1) When the vehicle speed is ≥ a, the output negative torque is provided by the motor energy recovery of the motor braking first. If the negative torque output by the motor energy recovery is withdrawn or cannot meet the braking torque required by the whole vehicle, the IPB brake controller performs hydraulic braking compensation so that the sum of the negative torque output by the motor energy recovery and the IPB hydraulic braking torque is close to or equal to the target torque required by the whole vehicle braking.

[0010] 2) When b < vehicle speed < a, adjust the ratio of motor braking and hydraulic braking torque according to the set slope. As the vehicle speed decreases, the hydraulic braking ratio gradually increases. The adjustment method of the set slope is as follows: when the vehicle speed is a, the motor braking ratio is 1 and the hydraulic braking ratio is 0; when the vehicle speed is b, the motor braking ratio is 0 and the hydraulic braking ratio is 1; the electric braking ratio... Hydraulic braking ratio f h y d ＝ 100%-f mo t or v is the current vehicle speed, v b For vehicle speed, v a Let the vehicle speed be a;

[0011] 3) When c < vehicle speed ≤ b, the target torque required for vehicle braking is entirely provided by hydraulic braking;

[0012] 4) When the vehicle speed is ≤c, the vehicle is parked in place by hydraulic braking and hydraulic holding is performed.

[0013] The three optimal vehicle speeds are: a = 15 kph, b = 7 kph, and c = 5 kph.

[0014] In step 1), the vehicle controller sends a hydraulic compensation request signal and a hydraulic braking torque request value to the IPB according to a set slope. After receiving the signal, the IPB brake controller performs a hydraulic braking response and feeds back the braking torque. The compensation torque does not exceed the target torque of the vehicle braking requirement based on the accelerator pedal analysis.

[0015] This sets the slope, according to the speed lookup tab (e.g.) Figure 2 At low speeds less than 5 kph, the torque slope is less than ±50 Nm / s; at speeds less than 7 kph, the slope is less than ±350 Nm / s; and at other speeds, the slope is relaxed to ±10000 Nm / s.

[0016] In step 4), when the vehicle is parked, if the IPB hydraulic pressure remains for more than a set time, the EPB electronic parking brake will take over the IPB parking brake.

[0017] Real-time vehicle slope information is obtained during single-pedal driving mode;

[0018] Uphill condition: The slope compensation positive torque is estimated based on the current slope to counteract the component of the vehicle's weight on the slope. The greater the slope, the greater the compensation positive torque. If the driver releases the accelerator, the braking force is analyzed and the vehicle is decelerated to the set speed through the negative torque of the motor. Then, a hold command is sent, and the chassis receives the hold command and puts the vehicle in place.

[0019] Downhill condition: The slope compensation negative torque is estimated based on the current slope to counteract the component of the vehicle's weight on the slope. The greater the slope, the greater the compensation negative torque. When the driver releases the accelerator, the braking force is analyzed and the vehicle is decelerated to the set speed through the negative torque of the motor. Then, a hold command is sent, and the chassis receives the hold command and puts the vehicle in place.

[0020] Once the single-pedal driving mode is activated, the driving modes are mutually exclusive, and switching between driving modes is not allowed. Simultaneously, "slow mode" and "hold mode" are activated.

[0021] The one-pedal function cannot be turned on or off while the vehicle is in motion. When the ADS function is activated, the one-pedal function is deactivated and cannot be activated, and the energy recovery level will be prohibited from being adjusted.

[0022] To activate one-pedal driving mode, the following conditions must be met simultaneously:

[0023] Condition 1: The vehicle is stopped and in Park (P) gear;

[0024] Condition 2: The steep slope descent function is closed.

[0025] Condition 3: The motor, battery, and IPB system are not faulty;

[0026] Condition 4: The E-Peda button is pressed.

[0027] A single-pedal torque control system for an electric vehicle includes a VDC (Variable Discharge Control) unit. The VDC communicates with a BMS (Battery Management System), MCU (Microcontroller Unit), BCM (Battery Management Module), IPB (Installation Barrier), and EPB (Electronic Power Supply) via a CAN network. The IPB and EPB communicate with each other via the CAN network. The VDC communicates with an IHU (Integrated User Unit) via a service signal. The control system executes the single-pedal torque control method for the electric vehicle as described above.

[0028] In the single-pedal control process of this invention, the motor braking and hydraulic braking are coordinated with each other, and the degradation of any one component is compensated by the other component, which improves the robustness of the system. Attached Figure Description

[0029] The following is a brief explanation of the content represented by each figure in this specification:

[0030] Figure 1 This is a block diagram illustrating the principle of a single-pedal torque control system for an electric vehicle.

[0031] Figure 2 To set the slope table. Detailed Implementation

[0032] The following description, with reference to the accompanying drawings, details the specific implementation of the present invention, including the shape and structure of each component, the relative positions and connections between the parts, the function and working principle of each part, the manufacturing process, and the operation and use methods, to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solution of the present invention.

[0033] The one-pedal control method for electric vehicles needs to clarify that in special scenarios such as emergency braking and parking on steep inclines, the driver still needs to apply the brakes to achieve braking and stopping. In one-pedal driving mode, when the driver releases the accelerator pedal to a specific position, the vehicle controller controls the reverse drag (negative) torque according to the current vehicle state to achieve the effect of vehicle deceleration. Simultaneously, under normal system conditions, the vehicle controller prioritizes allocating the reverse drag torque to the motor to recover as much energy as possible and optimize vehicle energy consumption. If the motor's reverse drag braking unexpectedly disengages or the motor's capacity cannot meet the vehicle's braking torque requirements, the vehicle controller actively requests the IPB brake controller to perform hydraulic braking compensation, using the sum of the motor's reverse drag braking recovered torque and the IPB hydraulic braking torque to achieve the vehicle's required braking torque.

[0034] This invention is applicable to electric vehicles equipped with IPB (Integrated Power Braking) electro-hydraulic braking coordination control function, and mainly involves the various systems of the electric vehicle and their interactions, such as... Figure 2As shown, the system has a VDC, which communicates with the BMS, MCU, BCM, IPB, and EPB via a CAN network. The IPB and EPB communicate with each other via the CAN network. The VDC communicates with the I HU via a service signal.

[0035] The control method for single-pedal torque of electric vehicles based on the above system:

[0036] When the driver requests drive, the driving force is provided by the motor (positive torque);

[0037] When the driver requests braking (under negative torque):

[0038] When the vehicle speed is greater than or equal to a certain speed (a), motor reverse braking is used first. If motor reverse braking unexpectedly disengages or the motor capacity cannot meet the vehicle's braking torque requirements, the vehicle controller actively requests the IPB brake controller to perform hydraulic braking compensation. The sum of the motor reverse braking torque and the IPB hydraulic braking torque is used to achieve the vehicle's braking torque requirements. The vehicle controller sends a hydraulic compensation request signal and a hydraulic braking torque request value to the IPB at a certain slope. After receiving the signal, the IPB brake controller responds with hydraulic braking and feeds back the braking torque. The maximum compensation torque does not exceed the vehicle's target braking torque based on the accelerator pedal analysis.

[0039] When the vehicle speed is within a certain range (when b < vehicle speed < a), the vehicle controller actively switches the torque ratio of electric braking and hydraulic braking at a certain slope. When the speed reaches b, the electric braking is completely converted to hydraulic braking to ensure that the braking connection is shock-free.

[0040] When c < vehicle speed ≤ b, the target torque required for vehicle braking is entirely provided by hydraulic braking.

[0041] When the vehicle speed is less than or equal to a certain speed (C), the vehicle controller sends a parking hold signal to the IPB brake controller, requesting the IPB brake controller to keep the vehicle stationary through hydraulic braking. The IPB performs hydraulic holding (similar to AVH). When the hydraulic holding timeout exceeds a certain period of time, the EPB electronic parking brake takes over.

[0042] Slope compensation solution for single-pedal braking:

[0043] On level ground: The vehicle controller estimates the slope to be 0 and compensates 0 Nm. When the driver releases the accelerator, the vehicle controller analyzes the braking force and uses the negative torque of the motor to decelerate the vehicle to a certain speed. Then, it sends a parking hold command, and the chassis receives the hold command and puts the vehicle in parking mode.

[0044] Uphill driving: The vehicle controller estimates the specific gradient and compensates with positive torque based on the estimated gradient to counteract the component of the vehicle's weight on the slope. When the driver releases the accelerator, the vehicle controller interprets the braking force and reduces the vehicle speed to a certain speed through the negative torque of the motor, then sends a hold command. The chassis receives the hold command and puts the vehicle in parking mode.

[0045] Downhill driving: The vehicle controller estimates the specific gradient and compensates for the negative torque based on the estimated gradient to counteract the component of the vehicle's weight on the slope. When the driver releases the accelerator, the vehicle controller interprets the braking force and reduces the vehicle to a certain speed through the negative torque of the motor, then sends a hold command. The chassis receives the hold command and puts the vehicle in parking mode.

[0046] Single-pedal start:

[0047] 1. Once E-Peda l (referring to the single-pedal button, the same below) is activated, the driving modes are mutually exclusive and switching driving modes is not allowed;

[0048] 2. Before activating E-Peda, park the car, shift into Park (P), and confirm that the hill descent control function is turned off.

[0049] 3. When the motor, battery, and IPB system are functioning correctly, the single-pedal button will be highlighted for selectability. The single-pedal function must not be turned off or on while driving, and the E-Peda I button should be grayed out. Switching the single-pedal function is only permitted when the brake is applied while the vehicle is stopped.

[0050] 4. The ADS function takes precedence over the single-pedal function. When the ADS function is activated, the single-pedal function is deactivated and cannot be activated.

[0051] 5. After E-Peda is turned on, I HU will simultaneously unfold the soft switch buttons for "Slow Mode" and "Hold Mode";

[0052] 6. The default mode is slow-down, and the hold mode is optional when the IPB system and the three-electric system are fault-free;

[0053] 7. Once E-Peda is activated, the energy recovery level will be disabled for adjustment.

[0054] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A single-pedal torque control method for an electric vehicle, in a single-pedal driving mode: when the driver requests drive, the driving force is provided by the motor with positive torque; when the driver requests braking, negative torque is provided, characterized in that: When the driver releases the accelerator pedal to the preset opening and requests braking, the vehicle controller controls the output of negative torque to decelerate the vehicle according to the current vehicle status. The output negative torque is provided first by the motor energy recovery. If the negative torque output by the motor energy recovery is withdrawn or cannot meet the vehicle braking torque requirement, the IPB brake controller performs hydraulic braking compensation so that the sum of the negative torque output by the motor energy recovery and the IPB hydraulic braking torque is close to or equal to the target torque required by the vehicle braking. When the driver requests braking, braking control is performed based on vehicle speed information: 1) When the vehicle speed is ≥ a, the output negative torque is provided by the motor energy recovery of the motor braking first. If the negative torque output by the motor energy recovery is withdrawn or cannot meet the braking torque required by the whole vehicle, the IPB brake controller performs hydraulic braking compensation so that the sum of the negative torque output by the motor energy recovery and the IPB hydraulic braking torque is close to or equal to the target torque required by the whole vehicle braking. 2) When b < vehicle speed < a, adjust the ratio of motor braking and hydraulic braking torque according to the set slope. As the vehicle speed decreases, the ratio of hydraulic braking gradually increases. When b < vehicle speed < a, the ratio of motor braking and hydraulic braking torque is adjusted according to a set slope. As the vehicle speed decreases, the hydraulic braking ratio gradually increases. The adjustment method of the set slope is as follows: when the vehicle speed is a, the motor braking ratio is 1 and the hydraulic braking ratio is 0; when the vehicle speed is b, the motor braking ratio is 0 and the hydraulic braking ratio is 1; the electric braking ratio... Hydraulic braking ratio v is the current vehicle speed, v b Let the vehicle speed be b, v a Let the vehicle speed be a; 3) When c < vehicle speed ≤ b, the target torque required for vehicle braking is entirely provided by hydraulic braking; 4) When the vehicle speed is ≤c, the vehicle is stopped in place by hydraulic braking and hydraulic holding is performed.

2. The electric vehicle single-pedal torque control method according to claim 1, characterized in that: In step 1), the vehicle controller sends a hydraulic compensation request signal and a hydraulic braking torque request value to the IPB according to a set slope. After receiving the signal, the IPB brake controller performs a hydraulic braking response and feeds back the braking torque. The maximum compensation torque does not exceed the target torque of the vehicle braking requirement based on the accelerator pedal analysis.

3. The electric vehicle single-pedal torque control method according to claim 1, characterized in that: In step 4), when the vehicle is parked, if the IPB hydraulic pressure is maintained for more than a set time, the EPB electronic parking brake will take over the IPB parking brake.

4. The electric vehicle single-pedal torque control method according to any one of claims 1-3, characterized in that: Real-time vehicle slope information is obtained during single-pedal driving mode; Uphill condition: The slope compensation positive torque is estimated based on the current slope to counteract the component of the vehicle's weight on the slope. The greater the slope, the greater the compensation positive torque. If the driver releases the accelerator, the braking force is analyzed and the vehicle is decelerated to the set speed through the negative torque of the motor. Then, a hold command is sent, and the chassis receives the hold command and puts the vehicle in place. Downhill condition: The slope compensation negative torque is estimated based on the current slope to counteract the component of the vehicle's weight on the slope. The greater the slope, the greater the compensation negative torque. When the driver releases the accelerator, the braking force is analyzed and the vehicle is decelerated to the set speed through the negative torque of the motor. Then, a hold command is sent, and the chassis receives the hold command and puts the vehicle in place.

5. The electric vehicle single-pedal torque control method according to claim 4, characterized in that: Once the single-pedal driving mode is activated, the driving modes are mutually exclusive, and switching between driving modes is not allowed. Simultaneously, "slow mode" and "hold mode" are activated.

6. The electric vehicle single-pedal torque control method according to claim 5, characterized in that: The one-pedal function cannot be turned on or off while the vehicle is in motion. When the ADS function is activated, the one-pedal function is deactivated and cannot be activated, and the energy recovery level will be prohibited from being adjusted.

7. The electric vehicle single-pedal torque control method according to claim 6, characterized in that: To activate one-pedal driving mode, the following conditions must be met simultaneously: Condition 1: The vehicle is stopped and in Park (P) gear; Condition 2: The steep slope descent function is closed. Condition 3: The motor, battery, and IPB system are not faulty; Condition 4: The E-Pedal button is pressed.

8. A single-pedal torque control system for an electric vehicle, the system comprising a VDC, wherein the VDC communicates with a BMS, MCU, BCM, IPB, and EPB via a CAN network, the IPB and EPB communicate with each other via a CAN network, and the VDC communicates with an IHU via a service signal, characterized in that: The control system executes the electric vehicle single-pedal torque control method as described in any one of claims 1-7.

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