Control system and method for abnormal driving direction of pure electric vehicle

Abstract

The invention discloses a control system and method for the abnormal driving direction of a pure electric vehicle. The method comprises the steps that whether a vehicle is in an out-of-gear state or not is determined according to the current gear switching-out state of the vehicle; according to the current out-of-gear state and the vehicle driving state of the vehicle, the vehicle is controlled as follows: when the vehicle is in a reverse driving state and is not in the out-of-gear state, an initial torque value is obtained according to the current accelerator pedal opening degree; carrying out negation calculation on each torque limit value in a reverse state, and then taking a minimum value as a driving torque limit value; determining a final torque value of the vehicle according to the initial torque value and the driving torque limit value; and controlling the vehicle according to the final torque value of the vehicle. By means of the method, the risks that the torque exceeds the limit value possibly in the reverse state and continuous reverse abnormal walking is caused by other reverse driving can be reduced or avoided, torque control in the gear shifting transition period does not suddenly change, and the pause driving feeling generated by gear shifting is avoided.

Description

Technical Field

[0001] This invention belongs to the field of vehicle control technology, specifically relating to a control system and method for a pure electric vehicle when its driving direction is abnormal. Background Technology

[0002] Pure electric vehicles are driven by an electric motor. Both D (Drive) and R (Reverse) are driving gears. When driving in D gear, the controller sends a forward direction command and a positive torque demand to the motor system. When regenerating braking / coasting energy in D gear, it sends a forward direction command and a negative torque demand. When driving in R gear, it sends a reverse direction command and a positive torque demand. When regenerating braking / coasting energy in R gear, it sends a reverse direction command and a negative torque demand. The motor system operates according to the direction and torque demand commands.

[0003] When switching drive gears, there may be a short period of disengagement due to the signal transmission and response feedback time between various systems. During the disengagement state, the control of driving direction and torque may be in a transitional state. At this time, the control of the motor direction change needs to be especially careful to avoid incorrect control of the motor direction.

[0004] In addition, when driving a pure electric vehicle, there may be situations where the current gear is opposite to the vehicle's driving direction or the motor's direction. That is, the vehicle may reverse in D gear or move forward in R gear. For example, when driving in D gear on a steep slope, the vehicle may roll backward. In this case, the actual driving direction of the vehicle is opposite to the driving direction required by the driver, which is dangerous. This should be avoided as much as possible or the vehicle should be restored to normal as soon as possible.

[0005] One existing technology involves executing zero torque output when the power source controller detects that the torque output is opposite to the gear position. This may occur in special road conditions such as rolling backwards on steep slopes, even if there are no malfunctions or errors in the vehicle-end components. Executing zero torque means the vehicle loses power. Another existing technology limits the allowable torque at the wheel ends to 0 when the torque direction is inconsistent with the gear direction. However, both of these methods, due to the unreasonable execution of zero torque or torque limiting strategies, pose safety risks such as continuous reverse movement of the vehicle and power interruption. At the same time, the short-term disengagement state during gear shifting may cause sudden torque changes, resulting in a jerky driving experience. Summary of the Invention

[0006] Pure electric vehicles are driven by an electric motor. Both D (Drive) and R (Reverse) are driving gears. In D gear, the controller sends a forward direction command and positive torque demand to the motor system. In D gear for braking / coasting energy recovery, it sends a forward direction command and negative torque demand. In R gear, it sends a reverse direction command and positive torque demand, and in R gear for braking / coasting energy recovery, it sends a reverse direction command and negative torque demand. The motor system operates according to the direction and torque demand commands. During gear shifting, due to the signal transmission and response feedback time between systems, there may be a brief disengagement state. During this disengagement state, the control of driving direction and torque may be in a transitional state. Therefore, special care must be taken when controlling changes in motor direction during this time to avoid incorrect motor direction control.

[0007] In addition, when driving a pure electric vehicle, there may be situations where the current gear is opposite to the vehicle's driving direction or the motor's direction. That is, the vehicle may reverse in D gear or move forward in R gear. For example, when driving in D gear on a steep slope, the vehicle may roll backward. In this case, the actual driving direction of the vehicle is opposite to the driving direction required by the driver, which is dangerous. This should be avoided as much as possible or the vehicle should be restored to normal as soon as possible.

[0008] This invention addresses the determination of whether a pure electric vehicle is in a disengaged state or in a reverse driving state in torque control. It proposes a control system and method for pure electric vehicles when the driving direction is abnormal, and a method for controlling and quickly restoring the torque limit value in the reverse driving state. This can reduce or avoid the risks of torque exceeding the limit value and other risks caused by continuous reverse driving in the reverse state.

[0009] A control system for a pure electric vehicle when its driving direction is abnormal, which achieves one of the objectives of this invention, includes: Disengagement Status Determination Module: Used to determine whether the vehicle is in a disengaged state based on the current gear position of the vehicle. Torque control module: used to control the vehicle according to the current disengagement state and driving state of the vehicle. The control method includes: when the vehicle driving state is reverse driving state and the vehicle is not in disengagement state, obtaining an initial torque value according to the current accelerator pedal opening; determining the final torque value of the vehicle according to the initial torque value and the driving torque limit value; and controlling the vehicle according to the final torque value of the vehicle.

[0010] Furthermore, the vehicle driving state includes a forward driving state and a reverse driving state, and the determination method includes: When the vehicle is in forward gear, the motor is rotating forward and the vehicle is not stationary, the vehicle's driving state is the normal driving state in forward gear. When the vehicle is in forward gear, the motor is reversing and the vehicle is not stationary, the vehicle's driving state is the reverse driving state under forward gear. When the vehicle is in reverse gear, the motor reverses and the vehicle is not stationary. At this time, the vehicle's driving state is the normal driving state under reverse gear. When the vehicle is in reverse gear, the motor is rotating forward and the vehicle is not stationary. At this time, the vehicle's driving state is the reverse driving state under reverse gear.

[0011] The method for determining that the vehicle is not stationary includes: the vehicle speed is greater than a set speed value, which may be 0.5 km / h, but is not limited to this.

[0012] Furthermore, when the vehicle is in reverse driving mode and not in disengaged state, the absolute value of the driving torque limit is taken, and the minimum value between the absolute value and the initial torque value is taken as the final torque value of the vehicle.

[0013] Furthermore, when the vehicle is in a reverse driving state, the method for calculating the torque limit value includes: Obtain the peak torque value of the vehicle's motor, the external characteristic torque limit value of the motor, and the current maximum torque value fed back by the MCU; The minimum value of the peak torque value of the motor, the external characteristic torque limit value of the motor, and the current maximum torque value fed back by the MCU is taken as the driving torque limit value after inverting all of them. The requested recovery torque limit value is 0.

[0014] Furthermore, the method for obtaining the initial torque value based on the current accelerator pedal opening includes: The maximum torque value corresponding to the motor speed of 0 under different accelerator pedal openings is obtained. A two-dimensional mapping table is formed based on each accelerator pedal opening and its corresponding maximum torque value when the motor speed is 0. When the vehicle enters the reverse drive state, the corresponding torque value is matched from the two-dimensional mapping table according to the current accelerator pedal opening as the initial torque value.

[0015] Furthermore, the method for controlling the vehicle based on its current disengagement state and driving state in the torque control module also includes: When the vehicle is in normal driving mode and not in disengaged mode, the peak torque value of the vehicle's motor, the external characteristic torque limit value of the motor, and the current maximum drivable torque value fed back by the MCU are obtained; the minimum value of the peak torque value of the motor, the external characteristic torque limit value of the motor, and the current maximum drivable torque value fed back by the MCU is taken as the driving torque limit value; the peak torque value of the vehicle's generator, the external characteristic torque limit value of the generator, and the current maximum generator torque value fed back by the MCU are obtained, and the maximum value of the peak torque value of the generator, the external characteristic torque limit value of the generator, and the current maximum generator torque value fed back by the MCU is taken as the recovery torque limit value.

[0016] Furthermore, when the vehicle is in a disengaged state, the vehicle maintains the torque magnitude and direction of the previous moment until the vehicle is no longer in a disengaged state; when the vehicle changes from a disengaged state to a non-disengaged state, the vehicle's driving state is re-determined based on the current gear and the vehicle's driving direction.

[0017] Furthermore, methods for determining whether a vehicle is in a disengaged state include: When the gear is shifted from driving to another gear or from reverse to another gear, the vehicle is considered to be in a disengaged state.

[0018] Furthermore, methods for determining whether a vehicle is in a disengaged state include: when the gear is engaged, if the absolute value of the torque is less than or equal to a set torque threshold, the vehicle is considered not to be in a disengaged state.

[0019] A control method for a pure electric vehicle when its driving direction is abnormal, which is a second objective of this invention, includes: Determine whether the vehicle is in a disengaged state based on the current gear position. The vehicle is controlled based on its current disengaged state and driving state. The control method includes: When the vehicle is in reverse drive mode and not in disengaged gear, the initial torque value is obtained based on the current accelerator pedal opening; the final torque value of the vehicle is determined based on the initial torque value and the drive torque limit value; and the vehicle is controlled based on the final torque value.

[0020] A non-transitory computer-readable storage medium for achieving the third objective of the present invention stores a computer program thereon, wherein when the computer program is executed by a processor, it implements the steps of a control method for when the driving direction of the pure electric vehicle is abnormal.

[0021] A computer program product for achieving the fourth objective of the present invention includes a computer program / instruction, which, when executed by a processor, implements the steps of a control method for abnormal driving direction of the pure electric vehicle.

[0022] The beneficial effects of this invention include: This invention determines whether a vehicle is in a disengaged state or in the opposite direction of the gear in torque control of a pure electric vehicle. It also proposes a method for controlling and quickly restoring the torque limit value in the opposite direction of the gear, which can reduce or avoid the risks of torque exceeding the limit value and other risks caused by continuous reverse driving in the opposite direction.

[0023] This invention identifies the brief disengagement state that may occur when switching gears in a pure electric vehicle and maintains the torque control during the disengagement state at the same time as before, so that the torque control during the gear shift transition does not change abruptly and avoids the jerky driving experience caused by gear shifting. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating an embodiment of the method described in this invention. Detailed Implementation

[0025] The following detailed embodiments are provided to explain the technical solutions of the claims of this invention, so that those skilled in the art can understand the claims. The scope of protection of this invention is not limited to the following specific embodiments. Any modifications made by those skilled in the art that incorporate the technical solutions of the claims but differ from the following detailed embodiments are also within the scope of protection of this invention.

[0026] This invention provides a control method for a pure electric vehicle when its driving direction is abnormal, such as... Figure 1 As shown, it includes the following steps: Step 1: Set the disengagement indicator When the vehicle shifts from D gear to P / R / N gear or from R gear to P / N / D gear, the disengagement flag is set to 1; after the gear is shifted out, the controller calculates that the absolute value of the torque is less than or equal to the set torque threshold, and then resets the disengagement flag to 0; the set torque threshold is set to a value close to 0 torque that cannot overcome the driving resistance to allow the vehicle to continue driving, which is obtained through dynamic simulation and practical experience. When the absolute value of the torque is less than or equal to the set torque threshold, it can be considered that there is no load driving, so as to avoid the delay in disengagement judgment. In this embodiment, the torque threshold is set to 3 Nm, but it is not limited to this value.

[0027] Step 2: Determine if the gear is disengaged The following method is used to determine whether a vehicle is in a reverse driving state: if the vehicle is not stationary (vehicle speed is greater than a set speed threshold) and the motor rotates in reverse in D gear or forward in R gear, the vehicle is considered to be in a reverse driving state; the set speed threshold is used to distinguish between temporary parking errors and actual driving, avoiding misjudgment at low speeds; in this embodiment, the set speed threshold is 0.5 km / h, but is not limited to this value; when the vehicle speed is ≤0.5 km / h, it may be a driver's temporary gear adjustment error, in which case the reverse state judgment is not triggered to avoid misjudgment; when the vehicle speed is >0.5 km / h, the vehicle can be considered to be in an abnormal direction during actual driving.

[0028] When the vehicle is in disengaged mode (i.e., when the disengaged mode indicator is 1), the controller maintains the torque output direction and magnitude from the previous moment (i.e., the torque value remains unchanged; for example, when shifting from D to R, the torque during disengagement remains the value from the last moment in D mode) until the disengaged mode indicator resets to 0. This technical effect includes: preventing vehicle jerking caused by sudden torque changes during gear shifts; otherwise, proceed to the next step. Step 3: Determine the reverse driving status When the vehicle is in reverse driving mode, steps 3.1 to 3.2 below are executed; otherwise, torque control and torque limiting control under normal driving conditions are executed, that is: the controller calculates the requested drive torque limit value (positive value) as... Min (Motor peak torque, motor external characteristic torque limit value, current maximum driveable torque value fed back by MCU), the requested torque limit value (negative value) is... Max (Peak torque of motor power generation, torque limit value of motor power generation external characteristic, current maximum power generation torque value fed back by MCU).

[0029] Step 3.1, Torque control in reverse driving mode According to the torque lookup table when the motor speed is 0, the torque is the largest value among different speeds when the motor speed is 0 at each accelerator pedal opening. Therefore, the motor can be restored to the reverse state as soon as possible to avoid the vehicle from continuously moving in the opposite direction. The torque lookup table is based on a pre-calibrated three-dimensional MAP of "accelerator pedal opening - motor speed - torque". When entering the reverse state, the motor speed parameter is forcibly set to 0. At this time, the torque value at each pedal opening is the maximum output torque when the speed is 0 at that opening (for example, when the pedal opening is 50% and the speed is 0, the torque can be found to be 60Nm by looking up the table). The motor is driven to quickly reverse through this torque, shortening the duration of the reverse state.

[0030] Step 3.2, Torque Limitation Control in Reverse Driving State In reverse mode, the motor's operating direction is opposite to the current gear direction, and the motor system is actually generating electricity (e.g., the motor reverses to generate electricity when in D gear in reverse). At this time, the direction of the torque output by the motor is opposite to the actual driving direction required. If the torque limit value of the driving state is directly controlled, the generated torque will be unrestricted, exacerbating the reverse driving. Therefore, it is necessary to invert the torque limit values ​​in reverse mode (e.g., the peak generated torque -100Nm is inverted to 100Nm) to ensure that the driving torque (reverse generated torque) of the vehicle in this reverse state can be limited within the torque limit value, ensuring that the torque control of the vehicle in reverse mode is consistent with the actual demand.

[0031] In some embodiments, when the vehicle is in reverse driving mode (i.e., in D / R gear reverse drive mode), the controller calculates the value of the requested drive torque limit. Min(Motor peak torque × -1, motor external characteristic torque limit × -1, MCU current maximum torque value × -1), requesting a torque limit of 0 Nm to prevent reverse torque from exceeding the limit. For example: if the motor peak torque is -100 Nm, the external characteristic limit is -80 Nm, and the MCU current maximum torque value is -90 Nm, then the drive torque limit is Min (100, 80, 90) = 80 Nm (limiting reverse torque to no more than 80 Nm).

[0032] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0033] This invention provides a control system for a pure electric vehicle when its driving direction is abnormal, comprising: Disengagement Status Determination Module: Used to determine whether the vehicle is in a disengaged state based on the current gear position of the vehicle. Torque control module: used to control the vehicle based on its current disengagement state and driving state, the control method including: When the vehicle is in reverse drive mode and not in disengaged gear, the initial torque value is obtained based on the current accelerator pedal opening; the final torque value of the vehicle is determined based on the initial torque value and the drive torque limit value; and the vehicle is controlled based on the final torque value.

[0034] In some embodiments, when the vehicle is in a reverse driving state, the method for calculating the driving torque limit value includes: Obtain the peak torque value of the vehicle's motor, the external characteristic torque limit value of the motor, and the current maximum torque value fed back by the MCU; The minimum value of the peak torque value of the motor, the external characteristic torque limit value of the motor, and the current maximum torque value fed back by the MCU is taken as the driving torque limit value after inverting all of them.

[0035] In some embodiments, the method for obtaining the initial torque value based on the current accelerator pedal opening includes: The maximum torque value corresponding to the motor speed of 0 under different accelerator pedal openings is obtained. A two-dimensional mapping table is formed based on each accelerator pedal opening and its corresponding maximum torque value when the motor speed is 0. When the vehicle enters the reverse drive state, the corresponding torque value is matched from the two-dimensional mapping table according to the current accelerator pedal opening as the initial torque value.

[0036] In some embodiments, the method for controlling the vehicle based on the vehicle's current disengaged state and driving state in the torque control module further includes: When the vehicle is in normal driving mode and not in disengaged mode, the following parameters are obtained: peak motor torque value, external characteristic torque limit value of the motor, and current maximum drivable torque value fed back by the MCU; the minimum value among these three parameters is taken as the driving torque limit value; peak generator torque value, external characteristic torque limit value of the motor, and current maximum generator torque value fed back by the MCU are also obtained; the maximum value among these three parameters is taken as the recovery torque limit value.

[0037] In some embodiments, when the vehicle is in a disengaged state, the vehicle maintains the torque magnitude and direction of the previous moment until the vehicle is no longer in a disengaged state; when the vehicle changes from a disengaged state to a non-disengaged state, the vehicle's driving state is re-determined based on the current gear and the vehicle's driving direction.

[0038] In some embodiments, the method for determining whether a vehicle is in a disengaged state includes: When the gear is shifted from driving to another gear or from reverse to another gear, the vehicle is considered to be in a disengaged state; when the gear is shifted out, if the absolute value of the torque is less than or equal to the set torque threshold, the vehicle is considered not to be in a disengaged state.

[0039] In some embodiments, when the vehicle is in reverse driving mode and not in disengaged state, the absolute value of the driving torque limit is taken, and the minimum value between the absolute value and the initial torque value is taken as the final torque value of the vehicle.

[0040] This invention also provides a non-transitory computer-readable storage medium storing a computer program. The computer program includes program instructions that, when executed by a processor, implement the various steps of the method described in this invention, which will not be elaborated further here.

[0041] The computer-readable storage medium can be the data transmission apparatus or the internal storage unit of a computer device provided in any of the foregoing embodiments, such as the hard disk or memory of the computer device. The computer-readable storage medium can also be the external storage device of the computer device, such as the plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc. equipped on the computer device.

[0042] Furthermore, the computer-readable storage medium may include both internal storage units and external storage devices of the computer device. The computer-readable storage medium is used to store the computer program and other programs and data required by the computer device. The computer-readable storage medium may also be used to temporarily store data that is to be output or has already been output.

[0043] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0044] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will 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 program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0045] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0046] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0047] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A control system for a pure electric vehicle when its driving direction is abnormal, characterized in that, include: Disengagement Status Determination Module: Used to determine whether the vehicle is in a disengaged state based on the current gear position of the vehicle. Torque control module: used to control the vehicle based on its current disengagement state and driving state, the control method including: When the vehicle is in reverse drive mode and not in disengaged gear, the initial torque value is obtained based on the current accelerator pedal opening; the final torque value of the vehicle is determined based on the initial torque value and the drive torque limit value; and the vehicle is controlled based on the final torque value.

2. The control system for abnormal driving direction of a pure electric vehicle as described in claim 1, characterized in that, When the vehicle is in reverse driving mode, the calculation method for the driving torque limit value includes: Obtain the peak torque value of the vehicle's motor, the external characteristic torque limit value of the motor, and the current maximum torque value fed back by the MCU; The minimum value of the peak torque value of the motor, the external characteristic torque limit value of the motor, and the current maximum torque value fed back by the MCU is taken as the driving torque limit value after inverting all of them.

3. The control system for abnormal driving direction of a pure electric vehicle as described in claim 1, characterized in that, Methods for obtaining the initial torque value based on the current accelerator pedal opening include: The maximum torque value corresponding to the motor speed of 0 under different accelerator pedal openings is obtained. A two-dimensional mapping table is formed based on each accelerator pedal opening and its corresponding maximum torque value when the motor speed is 0. When the vehicle enters the reverse drive state, the corresponding torque value is matched from the two-dimensional mapping table according to the current accelerator pedal opening as the initial torque value.

4. The control system for abnormal driving direction of a pure electric vehicle as described in claim 1 or 2, characterized in that, In the torque control module, the method for controlling the vehicle based on its current disengagement state and driving state also includes: When the vehicle is in normal driving mode and not in disengaged mode, the following parameters are obtained: peak motor torque value, external characteristic torque limit value of the motor, and current maximum drivable torque value fed back by the MCU; the minimum value among these three parameters is taken as the driving torque limit value; peak generator torque value, external characteristic torque limit value of the motor, and current maximum generator torque value fed back by the MCU are also obtained; the maximum value among these three parameters is taken as the recovery torque limit value.

5. The control system for abnormal driving direction of a pure electric vehicle as described in claim 1, characterized in that, When the vehicle is in a disengaged state, it maintains the torque magnitude and direction of the previous moment until it is no longer in a disengaged state; when the vehicle changes from a disengaged state to a non-disengaged state, the vehicle's driving state is re-determined based on the current gear and the vehicle's driving direction.

6. The control system for abnormal driving direction of a pure electric vehicle as described in claim 1, characterized in that, Methods for determining whether a vehicle is in a disengaged state include: When the gear is shifted from driving to another gear or from reverse to another gear, the vehicle is considered to be in a disengaged state. When a gear is engaged, if the absolute value of the torque is less than or equal to the set torque threshold, the vehicle is considered not to be in a disengaged state.

7. The control system for abnormal driving direction of a pure electric vehicle as described in claim 1 or 6, characterized in that, When the vehicle is in reverse driving mode and not in disengaged state, the absolute value of the driving torque limit is taken, and the minimum value between the absolute value and the initial torque value is taken as the final torque value of the vehicle.

8. A control method for a pure electric vehicle when its driving direction is abnormal in the system described in claim 1, characterized in that, include: Determine whether the vehicle is in a disengaged state based on the current gear position. The vehicle is controlled based on its current disengaged state and driving state. The control method includes: When the vehicle is in reverse drive mode and not in disengaged gear, the initial torque value is obtained based on the current accelerator pedal opening; the final torque value of the vehicle is determined based on the initial torque value and the drive torque limit value; and the vehicle is controlled based on the final torque value.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the control method for abnormal driving direction of a pure electric vehicle as described in claim 8.

10. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instruction is executed by the processor, it implements the steps of the control method for abnormal driving direction of the pure electric vehicle as described in claim 8.

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