CN109760519B - Steep slope slow descending control method and system for electric automobile - Google Patents
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Abstract
The invention discloses a steep descent control method and a system for an electric automobile, wherein the method comprises the following steps: acquiring vehicle parameters through a vehicle controller, and judging whether the vehicle can enter a sliding feedback state or not; if so, judging whether the acceleration of the vehicle is greater than a calibrated first threshold value and whether the speed of the vehicle is greater than a calibrated second threshold value; if so, entering a steep descent state, identifying a steep descent enabling signal through the vehicle controller, and providing a reverse torque for the vehicle, wherein the reverse torque is obtained by superposing an open-loop torque, a closed-loop torque and a sliding feedback torque; and after the vehicle decelerates, monitoring the acceleration and the speed of the vehicle, and if the acceleration of the vehicle is smaller than a calibrated third threshold value or the speed is smaller than a calibrated fourth threshold value, exiting the steep-slope slow-falling state. According to the invention, the steep descent function is realized without hardware such as a brake pedal, a ramp sensor, a steep descent setting button and the like, the cost of parts of the whole vehicle is reduced, and the potential safety hazard of the parts is reduced.
Description
Technical Field
The invention relates to the technical field of automobiles, in particular to a steep slope slow descending control method and system for an electric automobile.
Background
With the rapid development of the automobile industry and the continuous improvement of living conditions of people, automobiles become one of indispensable transportation tools for people to go out. The automobile keeping amount is increased year by year, and more people own private cars. At present, with the continuous improvement of environmental protection consciousness of people, new energy automobiles, especially electric automobiles are rapidly developed.
The conventional automobile steep-slope slow-descent system generally reduces gears by cooperating an engine braking force and an electric control braking system (such as ABS and ESC) and matching with a gearbox, so that the automobile runs at a low speed when going downhill. However, when the ramp slowly-descending enters, the hydraulic pump repeatedly applies pressure to brake, energy loss is caused, the brake disc is easy to generate heat, the ramp slowly-descending function can be possibly failed, the braking safety is affected, and the hydraulic braking system is low in efficiency, high in cost and easy to break down. Electric vehicles are generally only provided with a single-stage speed reducer, a complex gearbox is not used, and the downhill speed of the vehicle cannot be controlled by braking force generated by gear shifting.
At present, the steep descent function of the electric automobile mostly needs to be realized by means of hardware such as a ramp sensor, a steep descent setting button, a brake push rod, a brake disc temperature sensor and control brake pipeline pressure, so that the cost of the whole automobile parts is increased, and meanwhile, the parts are influenced by self strain, external environment interference and the like, so that the functional safety and stability are risky.
Disclosure of Invention
Therefore, one object of the present invention is to provide a steep descent control method for an electric vehicle, which does not need hardware such as a brake pedal, a slope sensor, and a steep descent setting button to implement a steep descent function, thereby reducing the cost of components of the entire vehicle and reducing the potential safety hazard caused by the components.
A steep descent control method for an electric vehicle comprises the following steps:
vehicle parameters are obtained through the vehicle control unit, and whether the vehicle can enter a sliding feedback state or not is judged according to the obtained vehicle parameters;
if the vehicle can enter a sliding feedback state, judging whether the acceleration of the vehicle is larger than a calibrated first threshold value and whether the speed of the vehicle is larger than a calibrated second threshold value;
if the acceleration of the vehicle is greater than a calibrated first threshold value and the speed of the vehicle is greater than a calibrated second threshold value, entering a steep descent state, identifying a steep descent enabling signal through the vehicle controller, and providing a reverse torque for the vehicle, wherein the reverse torque is obtained by superposing an open-loop torque, a closed-loop torque and a sliding feedback torque;
and after the vehicle decelerates, monitoring the acceleration and the speed of the vehicle, if the acceleration of the vehicle is smaller than a calibrated third threshold value or the speed is smaller than a calibrated fourth threshold value, exiting the steep descent state, performing a coasting state, and driving along a ramp by using a reverse torque generated by the current coasting torque, wherein the third threshold value is smaller than the first threshold value, and the fourth threshold value is smaller than the second threshold value.
The steep descent control method for the electric automobile provided by the invention at least has the following beneficial effects:
(1) the method can realize the function of the steep descent without hardware such as a brake pedal, a ramp sensor, a steep descent setting button and the like, reduces the cost of parts of the whole vehicle, reduces the functional potential safety hazard brought by the parts, and particularly reduces the potential safety hazard brought by heating and abrasion of a brake disc;
(2) when the acceleration is greater than a first threshold value and the speed is greater than a second threshold value, entering a steep descent state, and identifying a steep descent enabling signal through the vehicle controller to provide a reverse torque for the vehicle; when the acceleration is smaller than a third threshold value and the speed is smaller than a fourth threshold value, the vehicle exits from a steep slope slow descending state and is in a sliding state, so that the full recovery of energy can be realized in the downhill process of the whole vehicle, and the energy utilization rate is improved;
(3) the reverse torque of the steep descent is obtained by superposing the open-loop torque, the closed-loop torque and the sliding feedback torque, has the characteristic of torque linear transition, can ensure that the speed of the vehicle linearly and stably rises or falls when the vehicle runs on a ramp, and has no abrupt and jerky feeling: when the ramp is increased, the reverse torque is linearly increased, and the vehicle speed is stably reduced; when the ramp is reduced, the reverse torque is linearly reduced until the vehicle exits from the ramp slow descending state and enters a sliding feedback state, and the vehicle is smooth and comfortable.
In addition, according to the method for controlling a steep descent of an electric vehicle of the present invention, the following additional technical features may be further provided:
further, the step of acquiring vehicle parameters through the vehicle control unit and judging whether the vehicle can enter a coasting feedback state according to the acquired vehicle parameters includes:
acquiring a motor rotating speed signal, an accelerator pedal depth signal, a brake pedal signal, a brake switch signal, an energy feedback grade signal, a maximum monomer voltage value, a battery pack SOC signal and a gear switch signal through a vehicle control unit, converting the motor rotating speed signal into a vehicle speed signal to obtain the speed of the vehicle, and obtaining the acceleration of the vehicle after deriving the speed;
and judging the acquired signals through the vehicle control unit, and if the accelerator pedal depth signal, the brake pedal signal, the brake switch signal, the energy feedback grade signal, the maximum monomer voltage value, the battery pack SOC signal and the gear switch signal reach respective preset values, judging that the vehicle can enter a sliding feedback state.
Further, the step of identifying the steep descent enable signal through the vehicle controller and providing the vehicle with the reverse torque specifically includes:
judging whether the ramp slow descending function enabling is identified;
if the ramp slow-down function is identified to be enabled, respectively calculating the maximum values of the open-loop torque, the closed-loop P-direction torque, the closed-loop I-direction torque and the current sliding feedback torque;
determining a reverse torque, wherein the reverse torque is the sum of the open loop torque, the closed loop P direction torque, the closed loop I direction torque and the maximum value of the current sliding feedback torque.
Further, the open loop torque is calculated using the following method:
calculating 0% slope resistance F1 at different speeds by a vehicle sliding function, calculating slope resistance at different slopes, and taking an absolute value F2;
calculating a matrix of output power provided to the vehicle on the downhill slope at different vehicle speeds based on the different slopes according to F1 and F2;
calculating a matrix of output torques T provided to the vehicle on the ramps with different gradients and different vehicle speeds;
judging states of different energy feedback levels;
subtracting the absolute value of the feedback torque from the torque T, and calculating to obtain an open-loop torque matrix under different energy feedback levels, different gradients and different vehicle speeds;
calculating a matrix of acceleration corresponding to open-loop torque under different energy feedback levels, different gradients and different vehicle speeds, and taking an opposite number;
and obtaining an open-loop torque matrix corresponding to different acceleration under different energy feedback levels, different vehicle speeds, different gradients and different acceleration, and finally obtaining the open-loop torque.
Further, the method further comprises:
and after the vehicle decelerates, monitoring the acceleration and the speed of the vehicle, and returning to the step of identifying the steep descent enabling signal through the vehicle control unit if the vehicle does not meet the condition that the acceleration is smaller than a calibrated third threshold or the speed is smaller than a calibrated fourth threshold.
Further, after the step of determining whether the ramp descent function is enabled, the method further includes:
and if the ramp slow descending function is not identified to be enabled, returning to the sliding feedback state.
The invention also aims to provide a steep descent control system of the electric automobile, which can realize the steep descent function without hardware such as a brake pedal, a ramp sensor, a steep descent setting button and the like, reduce the cost of parts of the whole automobile and reduce the potential safety hazard caused by the parts.
A steep descent control system of an electric vehicle, the system comprising:
the acquisition and judgment module is used for acquiring vehicle parameters through the vehicle controller and judging whether the vehicle can enter a sliding feedback state according to the acquired vehicle parameters;
the first judgment module is used for judging whether the acceleration of the vehicle is larger than a calibrated first threshold value and whether the speed of the vehicle is larger than a calibrated second threshold value or not if the vehicle can enter a sliding feedback state;
the system comprises an enabling identification module, a control module and a control module, wherein the enabling identification module is used for entering a steep descent state if the acceleration of a vehicle is greater than a calibrated first threshold value and the speed of the vehicle is greater than a calibrated second threshold value, identifying a steep descent enabling signal through a vehicle controller and providing a reverse torque for the vehicle, and the reverse torque is obtained by overlapping an open-loop torque, a closed-loop torque and a sliding feedback torque;
and the deceleration monitoring module is used for monitoring the acceleration and the speed of the vehicle after the vehicle decelerates, and if the acceleration of the vehicle is smaller than a calibrated third threshold value or the speed is smaller than a calibrated fourth threshold value, the vehicle exits from a steep grade descent state, performs a coasting state, and runs along a ramp by using a reverse torque generated by the current coasting torque, wherein the third threshold value is smaller than the first threshold value, and the fourth threshold value is smaller than the second threshold value.
The steep descent control system of the electric automobile provided by the invention at least has the following beneficial effects:
(1) the method can realize the function of the steep descent without hardware such as a brake pedal, a ramp sensor, a steep descent setting button and the like, reduces the cost of parts of the whole vehicle, reduces the functional potential safety hazard brought by the parts, and particularly reduces the potential safety hazard brought by heating and abrasion of a brake disc;
(2) when the acceleration is greater than a first threshold value and the speed is greater than a second threshold value, entering a steep descent state, and identifying a steep descent enabling signal through the vehicle controller to provide a reverse torque for the vehicle; when the acceleration is smaller than a third threshold value or the speed is smaller than a fourth threshold value, the vehicle exits from a steep slope slow descending state and is in a sliding state, so that the full recovery of energy can be realized in the downhill process of the whole vehicle, and the energy utilization rate is improved;
(3) the reverse torque of the steep descent is obtained by superposing the open-loop torque, the closed-loop torque and the sliding feedback torque, has the characteristic of torque linear transition, can ensure that the speed of the vehicle linearly and stably rises or falls when the vehicle runs on a ramp, and has no abrupt and jerky feeling: when the ramp is increased, the reverse torque is linearly increased, and the vehicle speed is stably reduced; when the ramp is reduced, the reverse torque is linearly reduced until the vehicle exits from the ramp slow descending state and enters a sliding feedback state, and the vehicle is smooth and comfortable.
In addition, the steep descent control system for the electric vehicle according to the present invention may further have the following additional technical features:
further, the obtaining and determining module is specifically configured to:
acquiring a motor rotating speed signal, an accelerator pedal depth signal, a brake pedal signal, a brake switch signal, an energy feedback grade signal, a maximum monomer voltage value, a battery pack SOC signal and a gear switch signal through a vehicle control unit, converting the motor rotating speed signal into a vehicle speed signal to obtain the speed of the vehicle, and obtaining the acceleration of the vehicle after deriving the speed;
and judging the acquired signals through the vehicle control unit, and if the accelerator pedal depth signal, the brake pedal signal, the brake switch signal, the energy feedback grade signal, the maximum monomer voltage value, the battery pack SOC signal and the gear switch signal reach respective preset values, judging that the vehicle can enter a sliding feedback state.
Further, the enabling identification module is specifically configured to:
judging whether the ramp slow descending function enabling is identified;
if the ramp slow-down function is identified to be enabled, respectively calculating the maximum values of the open-loop torque, the closed-loop P-direction torque, the closed-loop I-direction torque and the current sliding feedback torque;
and determining a reverse torque according to the calculated open-loop torque, the closed-loop P-direction torque, the closed-loop I-direction torque and the current maximum value of the sliding feedback torque, wherein the reverse torque is the sum of the open-loop torque, the closed-loop P-direction torque, the closed-loop I-direction torque and the current maximum value of the sliding feedback torque.
Further, the enabling identification module calculates the open-loop torque by specifically adopting the following method:
calculating 0% slope resistance F1 at different speeds by using a vehicle sliding function, calculating slope resistance at different slopes, and taking an absolute value F2;
calculating a matrix of output power F provided for the vehicle on the slopes with different gradients and different vehicle speeds according to F1 and F2;
calculating a matrix of output torques T provided to the vehicle on the ramps with different gradients and different vehicle speeds;
judging states of different energy feedback levels;
subtracting the absolute value of the feedback torque from the torque T, and calculating to obtain an open-loop torque matrix under different energy feedback levels, different gradients and different vehicle speeds;
calculating to obtain a matrix of acceleration a corresponding to open-loop torque under different energy feedback levels, different gradients and different vehicle speeds, and taking an opposite number;
and obtaining an open-loop torque matrix corresponding to different accelerations under different energy feedback levels, different vehicle speeds and different gradients.
Further, the system further comprises:
and the first returning module is used for monitoring the acceleration and the speed of the vehicle after the vehicle decelerates, and returning to the step of identifying the steep descent enabling signal through the vehicle control unit if the vehicle does not meet the condition that the acceleration is smaller than a calibrated third threshold or the speed is smaller than a calibrated fourth threshold.
Further, the system further comprises:
and the second returning module is used for returning to the sliding feedback state if the ramp slow descending function is not identified to be enabled.
Drawings
The above and/or additional aspects and advantages of embodiments of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a flowchart of a steep descent control method of an electric vehicle according to a first embodiment of the invention;
FIG. 2 is a flow chart of a method of calculating open loop torque;
fig. 3 is a schematic structural diagram of a steep descent control system of an electric vehicle according to a second embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, a steep descent control method for an electric vehicle according to a first embodiment of the present invention includes steps S101 to S104:
s101, vehicle parameters are obtained through a vehicle controller, and whether the vehicle can enter a sliding feedback state or not is judged according to the obtained vehicle parameters;
wherein, step 101 may specifically include:
acquiring a motor rotating speed signal, an accelerator pedal depth signal, a brake pedal signal, a brake switch signal, an energy feedback grade signal, a maximum monomer voltage value, a battery pack SOC signal and a gear switch signal through a VCU (vehicle control unit), converting the motor rotating speed signal into a vehicle speed signal to obtain the speed of the vehicle, and obtaining the acceleration of the vehicle after deriving the speed;
and judging the acquired signals through the VCU of the vehicle controller, and if the accelerator pedal depth signal, the brake pedal signal, the brake switch signal, the energy feedback grade signal, the maximum monomer voltage value, the battery pack SOC signal and the gear switch signal reach respective preset values, judging that the vehicle can enter a sliding feedback state.
The respective preset values are, for example, specifically that the accelerator pedal depth signal is less than 2% of the set value, the brake switch is not turned on, the brake depth is less than 10% of the set value, the energy feedback level is any one of level 1, level 2 and level 3, the maximum cell voltage value is less than the set value U1, the SOC value of the battery pack is less than 100%, and the gear is the D gear, and it is determined that the vehicle can enter the coasting feedback state.
It can be understood that if at least one of the above condition values is not met, the vehicle cannot perform the coasting feedback state, and the subsequent steep descent operation cannot be performed.
S102, if the vehicle can enter a sliding feedback state, judging whether the acceleration of the vehicle is larger than a calibrated first threshold value and whether the speed of the vehicle is larger than a calibrated second threshold value;
wherein the content of the first and second substances,
s103, if the acceleration of the vehicle is larger than a calibrated first threshold value and the speed of the vehicle is larger than a calibrated second threshold value, entering a steep descent state, identifying a steep descent enable signal through the vehicle controller, and providing a reverse torque for the vehicle, wherein the reverse torque is obtained by superposing an open-loop torque, a closed-loop torque and a sliding feedback torque;
wherein, discernment abrupt slope slow descent enables the signal through vehicle control unit, and the step of providing reverse torque for the vehicle specifically includes:
judging whether the ramp slow descending function enabling is identified;
if the ramp slow-down function is identified to be enabled, respectively calculating the maximum values of the open-loop torque, the closed-loop P-direction torque, the closed-loop I-direction torque and the current sliding feedback torque;
determining a reverse torque, wherein the reverse torque is the sum of the open loop torque, the closed loop P direction torque, the closed loop I direction torque and the maximum value of the current sliding feedback torque. Namely, the reverse torque is equal to the open-loop torque + the closed-loop P direction torque + the closed-loop I direction torque + the maximum value of the current sliding feedback torque.
It will be appreciated that if the hill descent function is not identified as enabled, then the coast feedback condition is returned.
The open-loop torque is obtained by calculating and calibrating through a function based on different accelerations and different ramps, the open-loop torque changes linearly, I-direction and P-direction closed-loop torques are introduced to avoid repeated oscillation and sudden change of the torque, and the reverse torque prevents the vehicle from accelerating downhill and reduces the speed of the vehicle.
In specific implementation, referring to fig. 2, the open-loop torque may be calculated by the following method, including steps S1031 to S1037:
s1031, calculating 0% gradient resistance F1 (wherein, the vehicle speed is 10 km/h-100 km/h, and the 0% gradient resistance can be calculated by taking 10km/h as a unit) under different vehicle speeds by using a vehicle sliding function, calculating the gradient resistance under different gradients, and taking an absolute value F2 (wherein, the gradient resistance under each gradient can be calculated by taking 1% gradient as a unit) under the different gradients;
s1032, calculating a matrix of output power provided to the vehicle on the slope under different slopes and different vehicle speeds according to F1 and F2 (namely MAP, the same below);
s1033, calculating a matrix of output torques T provided for the vehicle by the vehicle on the slopes with different gradients and different vehicle speeds;
s1034, judging states of different energy feedback levels;
s1035, subtracting the absolute value of the feedback torque from the torque T, and calculating to obtain an open-loop torque matrix under different energy feedback levels, different gradients and different vehicle speeds;
s1036, calculating a matrix of accelerated speeds corresponding to open-loop torques under different energy feedback levels, different gradients and different vehicle speeds, and taking opposite numbers;
and S1037, obtaining an open-loop torque matrix corresponding to different acceleration rates under different energy feedback levels, different vehicle speeds and different gradients, and finally obtaining an open-loop torque.
And S104, after the vehicle decelerates, monitoring the acceleration and the speed of the vehicle, and if the acceleration of the vehicle is smaller than a calibrated third threshold value or the speed is smaller than a calibrated fourth threshold value, quitting the steep descent state, performing the coasting state, and driving along a slope by using the reverse torque generated by the current coasting torque, wherein the third threshold value is smaller than the first threshold value, and the fourth threshold value is smaller than the second threshold value.
If the acceleration of the vehicle is smaller than the calibrated third threshold value or the speed is smaller than the calibrated fourth threshold value, the vehicle exits from the steep-slope slow descending state, the coasting state is carried out, the reverse torque generated by the current coasting torque is utilized to drive along the slope, and the vehicle speed is reduced under the action of the coasting torque.
After the vehicle decelerates, the acceleration and the speed of the vehicle are continuously monitored, and if the vehicle does not meet the condition that the acceleration is smaller than the calibrated third threshold or the speed is smaller than the calibrated fourth threshold, the step of identifying the steep descent enabling signal through the vehicle controller is returned, namely the step S103 is returned.
According to the steep descent control method for the electric automobile provided by the embodiment, at least the following beneficial effects are achieved:
(1) the method can realize the function of the steep descent without hardware such as a brake pedal, a ramp sensor, a steep descent setting button and the like, reduces the cost of parts of the whole vehicle, reduces the functional potential safety hazard brought by the parts, and particularly reduces the potential safety hazard brought by heating and abrasion of a brake disc;
(2) when the acceleration is greater than a first threshold value and the speed is greater than a second threshold value, entering a steep descent state, and identifying a steep descent enabling signal through the vehicle controller to provide a reverse torque for the vehicle; when the acceleration is smaller than a third threshold value or the speed is smaller than a fourth threshold value, the vehicle exits from a steep slope slow descending state and is in a sliding state, so that the full recovery of energy can be realized in the downhill process of the whole vehicle, and the energy utilization rate is improved;
(3) the reverse torque of the steep descent is obtained by superposing the open-loop torque, the closed-loop torque and the sliding feedback torque, has the characteristic of torque linear transition, can ensure that the speed of the vehicle linearly and stably rises or falls when the vehicle runs on a ramp, and has no abrupt and jerky feeling: when the ramp is increased, the reverse torque is linearly increased, and the vehicle speed is stably reduced; when the ramp is reduced, the reverse torque is linearly reduced until the vehicle exits from the ramp slow descending state and enters a sliding feedback state, and the vehicle is smooth and comfortable.
Referring to fig. 3, based on the same inventive concept, a steep descent control system for an electric vehicle according to a second embodiment of the present invention includes:
the obtaining and judging module 10 is used for obtaining vehicle parameters through the vehicle controller and judging whether the vehicle can enter a sliding feedback state according to the obtained vehicle parameters;
the first judgment module 20 is configured to judge whether the acceleration of the vehicle is greater than a first calibrated threshold and whether the speed of the vehicle is greater than a second calibrated threshold if the vehicle can enter a coasting feedback state;
the enabling identification module 30 is configured to enter a steep descent state if the acceleration of the vehicle is greater than a calibrated first threshold and the speed of the vehicle is greater than a calibrated second threshold, identify a steep descent enabling signal through the vehicle controller, and provide a reverse torque for the vehicle, where the reverse torque is obtained by superimposing an open-loop torque, a closed-loop torque, and a coasting feedback torque;
and the deceleration monitoring module 40 is used for monitoring the acceleration and the speed of the vehicle after the vehicle decelerates, and if the acceleration of the vehicle is smaller than a calibrated third threshold value or the speed is smaller than a calibrated fourth threshold value, the vehicle exits from a steep-slope slow-descent state, performs a coasting state, and runs along a slope by using a reverse torque generated by the current coasting torque, wherein the third threshold value is smaller than the first threshold value, and the fourth threshold value is smaller than the second threshold value.
The obtaining and determining module 10 is specifically configured to:
acquiring a motor rotating speed signal, an accelerator pedal depth signal, a brake pedal signal, a brake switch signal, an energy feedback grade signal, a maximum monomer voltage value, a battery pack SOC signal and a gear switch signal through a vehicle control unit, converting the motor rotating speed signal into a vehicle speed signal to obtain the speed of the vehicle, and obtaining the acceleration of the vehicle after deriving the speed;
and judging the acquired signals through the vehicle control unit, and if the accelerator pedal depth signal, the brake pedal signal, the brake switch signal, the energy feedback grade signal, the maximum monomer voltage value, the battery pack SOC signal and the gear switch signal reach respective preset values, judging that the vehicle can enter a sliding feedback state.
Wherein, the enabling identification module 20 is specifically configured to:
judging whether the ramp slow descending function enabling is identified;
if the ramp slow-down function is identified to be enabled, respectively calculating the maximum values of the open-loop torque, the closed-loop P-direction torque, the closed-loop I-direction torque and the current sliding feedback torque;
and determining a reverse torque according to the calculated open-loop torque, the closed-loop P-direction torque, the closed-loop I-direction torque and the current maximum value of the sliding feedback torque, wherein the reverse torque is the sum of the open-loop torque, the closed-loop P-direction torque, the closed-loop I-direction torque and the current maximum value of the sliding feedback torque.
Wherein, the open-loop torque is calculated by the enabling identification module 20 by adopting the following method:
calculating 0% slope resistance F1 at different speeds by using a vehicle sliding function, calculating slope resistance at different slopes, and taking an absolute value F2;
calculating a matrix of output power F provided for the vehicle on the slopes with different gradients and different vehicle speeds according to F1 and F2;
calculating a matrix of output torques T provided to the vehicle on the ramps with different gradients and different vehicle speeds;
judging states of different energy feedback levels;
subtracting the absolute value of the feedback torque from the torque T, and calculating to obtain an open-loop torque matrix under different energy feedback levels, different gradients and different vehicle speeds;
calculating to obtain a matrix of acceleration a corresponding to open-loop torque under different energy feedback levels, different gradients and different vehicle speeds, and taking an opposite number;
and obtaining an open-loop torque matrix corresponding to different accelerations under different energy feedback levels, different vehicle speeds and different gradients.
Wherein the system further comprises:
the first returning module 50 is configured to monitor acceleration and speed of the vehicle after the vehicle decelerates, and return to the step of identifying the steep descent enable signal by the vehicle controller if the vehicle does not meet the condition that the acceleration is smaller than the calibrated third threshold or the speed is smaller than the calibrated fourth threshold.
Wherein the system further comprises:
a second return module 60 is configured to return to the coast feedback state if the hill descent function enablement is not identified.
According to the steep descent control system of the electric automobile provided by the embodiment, at least the following beneficial effects are achieved:
(1) the method can realize the function of the steep descent without hardware such as a brake pedal, a ramp sensor, a steep descent setting button and the like, reduces the cost of parts of the whole vehicle, reduces the functional potential safety hazard brought by the parts, and particularly reduces the potential safety hazard brought by heating and abrasion of a brake disc;
(2) when the acceleration is greater than a first threshold value and the speed is greater than a second threshold value, entering a steep descent state, and identifying a steep descent enabling signal through the vehicle controller to provide a reverse torque for the vehicle; when the acceleration is smaller than a third threshold value or the speed is smaller than a fourth threshold value, the vehicle exits from a steep slope slow descending state and is in a sliding state, so that the full recovery of energy can be realized in the downhill process of the whole vehicle, and the energy utilization rate is improved;
(3) the reverse torque of the steep descent is obtained by superposing the open-loop torque, the closed-loop torque and the sliding feedback torque, has the characteristic of torque linear transition, can ensure that the speed of the vehicle linearly and stably rises or falls when the vehicle runs on a ramp, and has no abrupt and jerky feeling: when the ramp is increased, the reverse torque is linearly increased, and the vehicle speed is stably reduced; when the ramp is reduced, the reverse torque is linearly reduced until the vehicle exits from the ramp slow descending state and enters a sliding feedback state, and the vehicle is smooth and comfortable.
The logic and/or steps represented in the flowcharts or otherwise described herein, e.g., an ordered listing of executable instructions that can be considered to implement logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.
More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit of a logic gate circuit specifically used for realizing a logic function for a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (10)
1. A steep descent control method for an electric vehicle is characterized by comprising the following steps:
vehicle parameters are obtained through the vehicle control unit, and whether the vehicle can enter a sliding feedback state or not is judged according to the obtained vehicle parameters;
if the vehicle can enter a sliding feedback state, judging whether the acceleration of the vehicle is larger than a calibrated first threshold value and whether the speed of the vehicle is larger than a calibrated second threshold value;
if the acceleration of the vehicle is greater than a calibrated first threshold value and the speed of the vehicle is greater than a calibrated second threshold value, entering a steep descent state, identifying a steep descent enabling signal through the vehicle controller, and providing a reverse torque for the vehicle, wherein the reverse torque is obtained by superposing an open-loop torque, a closed-loop torque and a sliding feedback torque;
and after the vehicle decelerates, monitoring the acceleration and the speed of the vehicle, if the acceleration of the vehicle is smaller than a calibrated third threshold value or the speed is smaller than a calibrated fourth threshold value, exiting the steep descent state, performing a coasting state, and driving along a ramp by using a reverse torque generated by the current coasting torque, wherein the third threshold value is smaller than the first threshold value, and the fourth threshold value is smaller than the second threshold value.
2. The method for controlling steep descent of an electric vehicle according to claim 1, wherein the step of obtaining vehicle parameters by the vehicle control unit and determining whether the vehicle can enter the coasting feedback state according to the obtained vehicle parameters comprises:
acquiring a motor rotating speed signal, an accelerator pedal depth signal, a brake pedal signal, a brake switch signal, an energy feedback grade signal, a maximum monomer voltage value, a battery pack SOC signal and a gear switch signal through a vehicle control unit, converting the motor rotating speed signal into a vehicle speed signal to obtain the speed of the vehicle, and obtaining the acceleration of the vehicle after deriving the speed;
and judging the acquired signals through the vehicle control unit, and if the accelerator pedal depth signal, the brake pedal signal, the brake switch signal, the energy feedback grade signal, the maximum monomer voltage value, the battery pack SOC signal and the gear switch signal reach respective preset values, judging that the vehicle can enter a sliding feedback state.
3. The method for controlling steep descent of an electric vehicle according to claim 1, wherein the step of identifying the steep descent enable signal by the vehicle control unit and providing the vehicle with the reverse torque specifically comprises:
judging whether the ramp slow descending function enabling is identified;
if the ramp slow-down function is identified to be enabled, respectively calculating the maximum values of the open-loop torque, the closed-loop P-direction torque, the closed-loop I-direction torque and the current sliding feedback torque;
determining a reverse torque, wherein the reverse torque is the sum of the open loop torque, the closed loop P direction torque, the closed loop I direction torque and the maximum value of the current sliding feedback torque.
4. The steep descent control method for an electric vehicle according to claim 3, wherein the open-loop torque is calculated by using:
calculating 0% slope resistance F1 at different speeds by a vehicle sliding function, calculating slope resistance at different slopes, and taking an absolute value F2;
calculating a matrix of output power provided to the vehicle on the downhill slope at different vehicle speeds based on the different slopes according to F1 and F2;
calculating a matrix of output torques T provided to the vehicle on the ramps with different gradients and different vehicle speeds;
judging states of different energy feedback levels;
subtracting the absolute value of the feedback torque from the torque T, and calculating to obtain an open-loop torque matrix under different energy feedback levels, different gradients and different vehicle speeds;
calculating a matrix of acceleration corresponding to open-loop torque under different energy feedback levels, different gradients and different vehicle speeds, and taking an opposite number;
and obtaining an open-loop torque matrix corresponding to different acceleration under different energy feedback levels, different vehicle speeds, different gradients and different acceleration, and finally obtaining the open-loop torque.
5. The steep descent control method of an electric vehicle according to claim 1, further comprising:
and after the vehicle decelerates, monitoring the acceleration and the speed of the vehicle, and returning to the step of identifying the steep descent enabling signal through the vehicle control unit if the vehicle does not meet the condition that the acceleration is smaller than a calibrated third threshold or the speed is smaller than a calibrated fourth threshold.
6. The steep descent control method of an electric vehicle according to claim 3, wherein after the step of determining whether the hill descent function is enabled, the method further comprises:
and if the ramp slow descending function is not identified to be enabled, returning to the sliding feedback state.
7. A steep descent control system for an electric vehicle, the system comprising:
the acquisition and judgment module is used for acquiring vehicle parameters through the vehicle controller and judging whether the vehicle can enter a sliding feedback state according to the acquired vehicle parameters;
the first judgment module is used for judging whether the acceleration of the vehicle is larger than a calibrated first threshold value and whether the speed of the vehicle is larger than a calibrated second threshold value or not if the vehicle can enter a sliding feedback state;
the system comprises an enabling identification module, a control module and a control module, wherein the enabling identification module is used for entering a steep descent state if the acceleration of a vehicle is greater than a calibrated first threshold value and the speed of the vehicle is greater than a calibrated second threshold value, identifying a steep descent enabling signal through a vehicle controller and providing a reverse torque for the vehicle, and the reverse torque is obtained by overlapping an open-loop torque, a closed-loop torque and a sliding feedback torque;
and the deceleration monitoring module is used for monitoring the acceleration and the speed of the vehicle after the vehicle decelerates, and if the acceleration of the vehicle is smaller than a calibrated third threshold value or the speed is smaller than a calibrated fourth threshold value, the vehicle exits from a steep grade descent state, performs a coasting state, and runs along a ramp by using a reverse torque generated by the current coasting torque, wherein the third threshold value is smaller than the first threshold value, and the fourth threshold value is smaller than the second threshold value.
8. The steep descent control system according to claim 7, wherein the obtaining and determining module is specifically configured to:
acquiring a motor rotating speed signal, an accelerator pedal depth signal, a brake pedal signal, a brake switch signal, an energy feedback grade signal, a maximum monomer voltage value, a battery pack SOC signal and a gear switch signal through a vehicle control unit, converting the motor rotating speed signal into a vehicle speed signal to obtain the speed of the vehicle, and obtaining the acceleration of the vehicle after deriving the speed;
and judging the acquired signals through the vehicle control unit, and if the accelerator pedal depth signal, the brake pedal signal, the brake switch signal, the energy feedback grade signal, the maximum monomer voltage value, the battery pack SOC signal and the gear switch signal reach respective preset values, judging that the vehicle can enter a sliding feedback state.
9. The steep descent control system according to claim 7, wherein the enabling identification module is specifically configured to:
judging whether the ramp slow descending function enabling is identified;
if the ramp slow-down function is identified to be enabled, respectively calculating the maximum values of the open-loop torque, the closed-loop P-direction torque, the closed-loop I-direction torque and the current sliding feedback torque;
and determining a reverse torque according to the calculated open-loop torque, the closed-loop P-direction torque, the closed-loop I-direction torque and the current maximum value of the sliding feedback torque, wherein the reverse torque is the sum of the open-loop torque, the closed-loop P-direction torque, the closed-loop I-direction torque and the current maximum value of the sliding feedback torque.
10. The steep descent control system according to claim 9, wherein the open-loop torque is calculated by the enabling identification module by specifically adopting the following method:
calculating 0% slope resistance F1 at different speeds by using a vehicle sliding function, calculating slope resistance at different slopes, and taking an absolute value F2;
calculating a matrix of output power F provided for the vehicle on the slopes with different gradients and different vehicle speeds according to F1 and F2;
calculating a matrix of output torques T provided to the vehicle on the ramps with different gradients and different vehicle speeds;
judging states of different energy feedback levels;
subtracting the absolute value of the feedback torque from the torque T, and calculating to obtain an open-loop torque matrix under different energy feedback levels, different gradients and different vehicle speeds;
calculating to obtain a matrix of acceleration a corresponding to open-loop torque under different energy feedback levels, different gradients and different vehicle speeds, and taking an opposite number;
and obtaining an open-loop torque matrix corresponding to different accelerations under different energy feedback levels, different vehicle speeds and different gradients.
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| CN110667393B (en) * | 2019-09-27 | 2023-05-23 | 上海伊控动力系统有限公司 | Recovery control method for sliding energy of pure electric vehicle |
| CN110654358B (en) * | 2019-10-30 | 2021-08-10 | 徐州徐工汽车制造有限公司 | Heavy truck steep slope slow descending control system and control method |
| CN111361556B (en) * | 2020-02-24 | 2022-03-08 | 浙江吉利新能源商用车集团有限公司 | Vehicle speed limit auxiliary control method and system |
| CN111439129A (en) * | 2020-04-14 | 2020-07-24 | 江西精骏电控技术有限公司 | Sliding energy recovery control method for electric automobile |
| CN111791713A (en) * | 2020-06-05 | 2020-10-20 | 力高(山东)新能源技术有限公司 | New energy automobile energy feedback control method and system |
| CN112477609B (en) * | 2020-11-10 | 2022-05-31 | 东风汽车集团有限公司 | Electric vehicle and electric vehicle sliding energy recovery method and recovery system |
| CN112848921A (en) * | 2021-01-27 | 2021-05-28 | 奇瑞新能源汽车股份有限公司 | Downhill method and device of electric automobile and vehicle |
| CN113276684B (en) * | 2021-06-30 | 2022-05-20 | 江铃汽车股份有限公司 | Sliding energy recovery control method for electric automobile |
| CN113829898B (en) * | 2021-11-15 | 2023-09-12 | 合众新能源汽车股份有限公司 | Vehicle control method and vehicle |
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