A control system and control method for hill-start assist driving of electric vehicles

Abstract

This invention relates to the field of electric vehicle control technology, specifically to a control system and method for hill-start assist driving of an electric vehicle. The control system includes a vehicle control unit (VCU) and a drive system. The VCU is used to acquire signals from the vehicle's CAN network, including signals from the vehicle's BMS system, MCU system, OBC system, accelerator pedal, brake pedal, gear position, and handbrake input signals. The drive system includes a motor controller (MCU), a motor, and a differential. The drive system executes different action responses in real time according to the control commands from the VCU. The control commands from the VCU include three types: operating mode, requested torque, and enable signal. The control method, by judging vehicle acceleration, can effectively reduce the vehicle's accidental entry into hill-start assist mode and accelerate the vehicle's entry into hill-start assist state, effectively reducing the vehicle's roll distance and providing comfort and safety during vehicle acceleration.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle control technology, specifically to a control system and control method for hill-start assist driving of electric vehicles. Background Technology

[0002] The hill-start assist function of existing electric vehicles, which uses slope sensors combined with automatic parking systems, has disadvantages such as high cost, long calibration cycle, high calibration development cost, and limited functionality. It is increasingly out of step with the increasingly competitive new energy vehicle market.

[0003] A search revealed Chinese Patent Publication No. CN111137137A, which discloses a control method, system, and hybrid vehicle for a hybrid electric vehicle. The control method includes: when the vehicle controller detects that the power battery is unavailable, it sends a target value for the bus voltage and a limit value for the generated torque to the motor controller; the motor controller detects the motor speed; when the difference between the speed and the motor idle speed is equal to or less than a preset first difference threshold, the motor controller controls the motor's generated torque to be less than the generated torque limit. The control method, system, and hybrid vehicle of this invention, when detecting that the power battery is unavailable and the motor speed is low, control the motor's generated torque through the motor controller to prevent the generated torque from exceeding the engine's current load capacity and causing the engine to stall.

[0004] However, during use, controlling the vehicle by whether the motor speed exceeds the threshold can easily cause the vehicle to mistakenly enter the anti-slip mode. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a control system and control method for hill-start assist driving of electric vehicles, which can judge the absolute value of vehicle acceleration, effectively reduce the vehicle from accidentally entering the anti-rollover mode and speed up the vehicle to enter the anti-rollover state.

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

[0007] A control system for hill-start assist driving of an electric vehicle without hill-start sensors, including a vehicle control unit (VCU) and a drive system;

[0008] The vehicle control unit (VCU) is used to acquire signals from the vehicle's CAN network, including signals from the vehicle's BMS system, MCU system, OBC system, accelerator pedal, brake pedal, gear position, and handbrake input signals.

[0009] The drive system includes a motor controller (MCU), a motor, and a differential. The drive system executes different action responses in real time according to the control commands from the vehicle controller (VCU).

[0010] Preferably, the control commands of the vehicle control unit (VCU) include three types: operating mode, requested torque, and enable signal.

[0011] Preferably, the vehicle controller (VCU) performs system conversion through its internal signal acquisition module and then transmits the data to the VCU's logic control module. After completing the logic operation, the parameters are transmitted to the torque output module. The torque output module calculates the required drive torque command for the motor and controls the drive system in parallel through CAN bus commands and hard-wired signals from the signal output module.

[0012] Preferably, the torque and speed data are filtered.

[0013] Preferably, the speed fluctuation is <20 Rpm in static conditions and <50 Rpm in dynamic conditions.

[0014] A control method for a hill-start assist driving control system for electric vehicles without hill-start sensors, the steps of which are as follows:

[0015] S11: The vehicle controller (VCU) determines whether the vehicle meets the Ready condition and whether it is ready to drive based on the vehicle's status.

[0016] S12: The vehicle control unit (VCU) determines whether the vehicle is stationary.

[0017] S13: The vehicle control unit (VCU) determines the stationary state of the vehicle by using the ABS speed signal or the motor speed.

[0018] S14: The vehicle control unit (VCU) uses hard-wired acquisition of gear position signals and vehicle status to determine whether the vehicle is in a valid forward gear.

[0019] S15: The vehicle controller (VCU) determines whether the motor speed is less than -50 RPM or the vehicle acceleration is less than the set value, and after maintaining this for 100ms, the vehicle enters the hill start assist mode.

[0020] S16: The vehicle controller (VCU) sends zero vehicle drive torque;

[0021] S17: By calculating the difference between the target vehicle speed and the actual vehicle speed in real time, the driving torque of the vehicle is adjusted adaptively by PID, so that the vehicle can drive automatically on the slope at the set speed.

[0022] S18: Determine the driver's driving intention by observing the state of the accelerator pedal;

[0023] S19: Calculates the vehicle's driving torque based on the depth of the accelerator pedal. When the required torque is greater than the actual driving torque of the vehicle, exits the hill start assist mode; when the required torque is less than the actual driving torque of the vehicle, continues to execute the hill start assist mode.

[0024] S20: The vehicle controller sends the required torque to the MCU motor controller to drive the vehicle normally and exits the hill start assist mode.

[0025] S21: The vehicle control unit (VCU) determines whether the vehicle is in a valid reverse gear by acquiring gear position signals and vehicle status via hard wiring.

[0026] S22: The vehicle controller (VCU) determines whether the motor speed is greater than 50 RPM or the vehicle acceleration is greater than the set value, and after maintaining this for 100ms, the vehicle enters the hill start assist mode.

[0027] S23: The vehicle control unit (VCU) determines whether the actual vehicle speed is greater than the set value. This status includes forward gear and reverse gear.

[0028] S24: When the actual vehicle speed is greater than the set value, the vehicle enters crawl mode and exits hill start assist mode.

[0029] Preferably, in step S17, if condition S15 is met, a positive torque is sent to drive the vehicle forward; if condition S22 is met, a negative torque is sent to drive the vehicle backward.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] By optimizing the vehicle controller software, real-time data is collected from the CAN bus and driving signals via hardwired acquisition. The algorithm determines the vehicle's driving trend and the driver's driving intention, enabling the vehicle to automatically drive at the calibrated speed after releasing the brake pedal when stopped on a slope without pressing the accelerator pedal. The hill start assist function automatically exits after the vehicle comes to a stop by pressing the brake pedal, and automatically re-enters after releasing the brake pedal.

[0032] Instead of simply determining whether the motor speed exceeds a certain threshold to enter anti-rollover mode, the system judges the vehicle's tendency to roll backward by measuring the absolute value of the vehicle's acceleration. By judging the vehicle's acceleration, the system can effectively reduce the number of vehicles that mistakenly enter anti-rollover mode and accelerate the vehicle's entry into anti-rollover state. This can effectively reduce the vehicle's rolling distance and provide both comfort and safety during vehicle acceleration.

[0033] When the vehicle enters the anti-rollover mode, it can move forward slowly without pressing the accelerator pedal when climbing a hill. Pressing the brake pedal will automatically disengage the vehicle. The VCU judges the vehicle's driving status, giving the vehicle the functions of crawling on flat ground and hill-start assist driving, rather than the traditional hill-start assist parking function.

[0034] This method enables vehicles to park on ramps without increasing hardware costs, improving driving comfort, reducing vehicle development costs, and shortening the vehicle development cycle. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the control system of the present invention.

[0037] Figure 2 This is a flowchart of the control method of the present invention. Detailed Implementation

[0038] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0039] Example 1

[0040] like Figure 1 As shown, this embodiment provides a control system for hill-start assist driving of an electric vehicle, which integrates the vehicle control unit (VCU) and the drive system.

[0041] The vehicle control unit (VCU) is used to acquire signals from the vehicle's CAN network, including signals from the vehicle's BMS system, MCU system, OBC system, accelerator pedal, brake pedal, gear position, and handbrake input signals.

[0042] The drive system includes a motor controller (MCU), a motor, and a differential. The drive system executes different action responses in real time according to the control commands from the vehicle controller (VCU).

[0043] Preferably, the control commands of the vehicle control unit (VCU) include three types: operating mode, requested torque, and enable signal.

[0044] Preferably, the vehicle controller (VCU) performs system conversion through its internal signal acquisition module and then transmits the data to the VCU's logic control module. After completing the logic operation, the parameters are transmitted to the torque output module. The torque output module calculates the required drive torque command for the motor and controls the drive system in parallel through CAN bus commands and hard-wired signals from the signal output module.

[0045] Preferably, the torque and speed data are filtered to effectively reduce noise interference.

[0046] Preferably, in a static state, the speed fluctuation is strictly controlled within 20 RPM; while in a dynamic state, the speed fluctuation is also required to not exceed 50 RPM, providing a strong guarantee for the smooth driving of the vehicle.

[0047] Example 2

[0048] Based on Example 1, such as Figure 2 As shown, a control method for a hill-start assist driving control system for an electric vehicle includes the following steps:

[0049] S11: The vehicle controller (VCU) determines whether the vehicle meets the Ready condition and whether it is ready to drive based on the vehicle's status.

[0050] S12: The vehicle control unit (VCU) determines whether the vehicle is stationary.

[0051] S13: The vehicle control unit (VCU) determines the stationary state of the vehicle by using the ABS speed signal or the motor speed.

[0052] S14: The vehicle control unit (VCU) uses hard-wired acquisition of gear position signals and vehicle status to determine whether the vehicle is in a valid forward gear.

[0053] S15: The vehicle controller (VCU) determines whether the motor speed is less than -50 RPM or the vehicle acceleration is less than the set value, and after maintaining this for 100ms, the vehicle enters the hill start assist mode.

[0054] S16: The vehicle controller (VCU) sends zero vehicle drive torque;

[0055] S17: By calculating the difference between the target vehicle speed and the actual vehicle speed in real time, the driving torque of the vehicle is adjusted adaptively by PID, so that the vehicle can drive automatically on the slope at the set speed.

[0056] S18: Determine the driver's driving intention by observing the state of the accelerator pedal;

[0057] S19: Calculates the vehicle's driving torque based on the depth of the accelerator pedal. When the required torque is greater than the actual driving torque of the vehicle, exits the hill start assist mode; when the required torque is less than the actual driving torque of the vehicle, continues to execute the hill start assist mode.

[0058] S20: The vehicle controller sends the required torque to the MCU motor controller to drive the vehicle normally and exits the hill start assist mode.

[0059] S21: The vehicle control unit (VCU) uses hard-wired acquisition of gear position signals and vehicle status to determine whether the vehicle is in a valid reverse gear.

[0060] S22: The vehicle controller (VCU) determines whether the motor speed is greater than 50 RPM or the vehicle acceleration is greater than the set value, and after maintaining this for 100ms, the vehicle enters the hill start assist mode.

[0061] S23: The vehicle control unit (VCU) determines whether the actual vehicle speed is greater than the set value. This status includes forward gear and reverse gear.

[0062] S24: When the actual vehicle speed is greater than the set value, the vehicle enters crawl mode and exits hill start assist mode.

[0063] Preferably, in step S17, if condition S15 is met, a positive torque is sent to drive the vehicle forward; if condition S22 is met, a negative torque is sent to drive the vehicle backward.

[0064] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the invention should also be covered within the protection scope of the invention. Therefore, the protection scope of the invention should be determined by the scope of the claims.

Claims

1. A control method for a control system of hill-start assist driving for electric vehicles, characterized in that, The steps include the following: S11: The vehicle controller (VCU) determines whether the vehicle meets the Ready condition and whether it is ready to drive based on the vehicle's status. If so, it executes S12. S12: The vehicle control unit (VCU) determines whether the vehicle is stationary. If so, it executes S13. S13: Determine if the vehicle has rolled away. If so, proceed to S14: S14: The vehicle control unit (VCU) collects the gear position signal and vehicle status through hard wiring to determine whether the vehicle is in a valid forward gear. If yes, execute S15; otherwise, execute S21. S15: The vehicle controller (VCU) determines that the vehicle's acceleration is less than or equal to a set value and maintains this value for 100ms. If not, proceed to S16; if so, proceed to S17. S16: The vehicle controller (VCU) sends zero vehicle drive torque; S17: By calculating the difference between the target vehicle speed and the actual vehicle speed in real time, the driving torque of the vehicle is adjusted adaptively by PID, so that the vehicle can drive automatically on the slope at the set speed. S18: Determine whether the driver has a driving intention by checking the state of the accelerator pedal. If yes, proceed to S19; otherwise, proceed to S23. S19: Calculate the vehicle's driving torque based on the depth of the accelerator pedal being pressed. When the required torque is greater than the current actual driving torque of the vehicle, exit the hill start assist mode and execute S20. If the required torque is less than the actual driving torque of the current vehicle, continue to execute the hill start assist mode and execute S17; S20: The vehicle controller sends the required torque to the MCU motor controller for normal vehicle driving and exits the hill start assist mode; S21: The vehicle control unit (VCU) collects the gear position signal and vehicle status through hard wiring to determine whether the vehicle is in a valid reverse gear. If so, it executes S22. S22: The vehicle control unit (VCU) determines that the vehicle's acceleration is greater than the set value and maintains this value for 100ms. If so, the vehicle enters the hill start assist mode. If so, S17 is executed. S23: The vehicle control unit (VCU) determines whether the actual vehicle speed is greater than the set value. This includes both forward and reverse gears. If so, S24 is executed. S24: When the actual vehicle speed is greater than the set value, the vehicle enters crawl mode and exits hill start assist mode.

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