CN113562072A - Steering control method and device for electric automobile - Google Patents

Steering control method and device for electric automobile Download PDF

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Publication number
CN113562072A
CN113562072A CN202010348017.1A CN202010348017A CN113562072A CN 113562072 A CN113562072 A CN 113562072A CN 202010348017 A CN202010348017 A CN 202010348017A CN 113562072 A CN113562072 A CN 113562072A
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China
Prior art keywords
steering
braking torque
wheel
torque
controlling
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CN202010348017.1A
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Chinese (zh)
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CN113562072B (en
Inventor
刘杰
李波
沈海燕
李国红
杜晓丰
马涛
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Beijing Electric Vehicle Co Ltd
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Beijing Electric Vehicle Co Ltd
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Publication of CN113562072A publication Critical patent/CN113562072A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D11/00—Steering non-deflectable wheels; Steering endless tracks or the like
    • B62D11/001—Steering non-deflectable wheels; Steering endless tracks or the like control systems
    • B62D11/003—Electric or electronic control systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
    • B60L15/2036—Electric differentials, e.g. for supporting steering vehicles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
    • B60L15/2045—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed for optimising the use of energy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/32—Control or regulation of multiple-unit electrically-propelled vehicles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D11/00—Steering non-deflectable wheels; Steering endless tracks or the like
    • B62D11/02—Steering non-deflectable wheels; Steering endless tracks or the like by differentially driving ground-engaging elements on opposite vehicle sides
    • B62D11/04—Steering non-deflectable wheels; Steering endless tracks or the like by differentially driving ground-engaging elements on opposite vehicle sides by means of separate power sources
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2220/00—Electrical machine types; Structures or applications thereof
    • B60L2220/40—Electrical machine applications
    • B60L2220/44—Wheel Hub motors, i.e. integrated in the wheel hub
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/42—Drive Train control parameters related to electric machines
    • B60L2240/423—Torque
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/72—Electric energy management in electromobility

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Power Engineering (AREA)
  • Automation & Control Theory (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)
  • Steering Control In Accordance With Driving Conditions (AREA)

Abstract

The invention discloses a steering control method and a device of an electric automobile.A hub motor is respectively arranged on each wheel of the electric automobile, and the hub motor of a front wheel is connected with an energy storage component; determining a target control mode according to the change rate of the corner, wherein the target control mode is as follows: a differential steering control mode or an electric power steering control mode; when the target control mode is determined to be the differential steering control mode, acquiring the energy storage state of the energy storage component, and acquiring the required braking torque of the wheels on the inner side of the steering and the required driving torque of the wheels on the outer side of the steering; and controlling the distribution of the braking torque to the inner wheels and the driving torque to the outer wheels according to the energy storage state to generate the required braking torque and the required driving torque. According to the scheme provided by the invention, stable steering is realized, energy consumption in the steering process is reduced, and the driving range of the whole vehicle is increased.

Description

Steering control method and device for electric automobile
Technical Field
The invention relates to the technical field of automobiles, in particular to a steering control method and device of an electric automobile.
Background
At present, the hub motor driven distributed pure electric automobile directly drives the automobile through the hub motor without a speed reducing mechanism, thereby saving the traditional parts such as a transmission shaft and the like, improving the efficiency of a transmission system and being an ideal driving mode of the electric automobile. The hub driving type distributed pure electric vehicle in the current market has no mass production vehicle type and is in a research and development stage.
Because the dynamics characteristics of the four-hub motor-driven electric automobile are greatly changed compared with the traditional automobile, the traditional steering control method cannot be directly adopted, and the pure electric automobile adopts a power battery pack for power supply, and the energy of the battery pack is limited, so how to reduce the energy consumption in the steering process while realizing the stable steering of the four-hub motor-driven electric automobile is a problem to be solved urgently at present.
Disclosure of Invention
In order to solve the technical problem, the invention provides a steering control method and a steering control device for an electric vehicle, which solve the problem of how to reduce energy consumption in the steering process while realizing stable steering of the four-hub motor-driven electric vehicle.
According to one aspect of the present invention, a steering control method for an electric vehicle is provided, where each wheel of the electric vehicle is provided with a hub motor, and the hub motors on two front wheels are connected with energy storage components, respectively, the method includes:
acquiring a turning angle change rate of a steering wheel under the condition that the electric automobile is determined to be subjected to steering control;
determining a target control mode according to the corner change rate, wherein the target control mode is as follows: a differential steering control mode or an electric power steering control mode;
under the condition that the target control mode is determined to be the differential steering control mode, acquiring an energy storage state of an energy storage component, wherein the energy storage state is used for indicating whether the energy storage component stores energy or not; acquiring a required braking torque of a wheel on the inner side of a steering wheel and a required driving torque of a wheel on the outer side of the steering wheel; and controlling the electric vehicle to distribute the braking torque of the wheels on the inner side of the steering and the driving torque of the wheels on the outer side of the steering according to the energy storage state so as to generate the required braking torque and the required driving torque.
Optionally, after determining the target control mode according to the rotation angle change rate, the method further includes:
under the condition that the target control mode is an electric control power-assisted steering control mode, providing power-assisted steering torque to the electric automobile through an electric control steering engine to complete power-assisted steering of the electric automobile;
and after the power-assisted steering is finished, controlling the electric automobile to enter the differential steering control mode.
Optionally, the determining a target control mode according to the rotation angle change rate includes:
when the turning angle change rate is larger than or equal to a first threshold value, determining that a target control mode is an electric control power-assisted steering control mode;
and when the turning angle change rate is smaller than the first threshold value, determining that the target control mode is differential steering control.
Optionally, the controlling the electric vehicle to distribute the braking torque to the inner wheels and distribute the driving torque to the outer wheels according to the energy storage state to generate the required braking torque and the required driving torque includes:
controlling an in-wheel motor on a steering outer wheel of the rear axle to provide the required drive torque of the steering outer wheel of the rear axle in the case that the energy storage state indicates that the energy storage component stores energy; and obtaining a first driving torque that is a maximum driving torque of an energy storage member on a wheel on a steering outer side of the front shaft and a first braking torque that is a maximum energy recovery braking torque of hub motors on wheels on a steering inner side of the front shaft and the rear shaft;
controlling the electric automobile to distribute the driving torque of the steering outer wheels of the front axle according to the first driving torque;
and controlling the electric automobile to distribute the braking torque of the steering inner side wheels of the front axle and the rear axle according to the first braking torque.
Optionally, the controlling, according to the first driving torque, the electric vehicle to distribute the driving torque to the steering outer wheels of the front axle comprises:
controlling an energy storage member on the steering outer side wheels of the front axle to provide the required drive torque of the steering outer side wheels of the front axle if the first drive torque is greater than or equal to the required drive torque;
and if the first driving torque is smaller than the required driving torque, controlling an energy storage component on the outer steering wheel of the front shaft to provide the first driving torque, and controlling a hub motor on the outer steering wheel of the front shaft to generate the driving torque of the difference value between the required driving torque and the first driving torque.
Optionally, the controlling the electric vehicle to distribute the braking torque of the steering inner wheels of the front axle and the rear axle according to the first braking torque includes:
if the first braking torque is larger than or equal to the required braking torque, controlling hub motors of the steering inner wheels of the front axle and the rear axle to respectively generate the required braking torque;
if the first braking torque is smaller than the required braking torque, the hub motors of the steering inner side wheels of the front axle and the rear axle are controlled to respectively generate the first braking torque, and the braking torques which are respectively provided by the hydraulic system for the steering inner side wheels of the front axle and the rear axle are controlled to be a first value;
wherein the first value is a difference between the demanded braking torque and the first braking torque.
Optionally, the controlling the electric vehicle to distribute the braking torque to the inner wheels and distribute the driving torque to the outer wheels according to the energy storage state to generate the required braking torque and the required driving torque includes:
in the case where the energy storage state indicates that the energy storage member is not storing energy, controlling in-wheel motors of the steered outer wheels of the front and rear axles to each generate the required driving torque; and obtaining a second braking torque and a third braking torque; wherein the second braking force is a maximum energy recovery braking torque of an energy storage component on a steering inner wheel of the front axle, and the third braking force is a maximum energy recovery braking torque of an in-wheel motor on a steering inner wheel of the rear axle;
controlling the electric automobile to distribute the braking torque of the steering inner side wheel of the front axle according to the second braking torque;
and controlling the electric automobile to distribute the braking torque of the steering inner side wheel of the rear axle according to the third braking torque.
Optionally, the controlling, according to the second braking torque, the distribution of the braking torque of the steered inner wheel of the front axle of the electric vehicle includes:
if the second braking torque is larger than or equal to the required braking torque, controlling an energy storage component on the steering inner side wheel of the front axle to provide the required braking torque of the steering inner side wheel of the front axle;
if the second braking torque is smaller than the required braking torque, acquiring a fourth braking torque which is the maximum energy recovery torque of a hub motor on a wheel on the steering inner side of the front axle; and controlling the electric automobile to distribute the braking torque of the steering inner side wheel of the front axle according to the second braking torque and the fourth braking torque.
Optionally, the controlling the electric vehicle to distribute the braking torque of the steering inner wheel of the front axle according to the second braking torque and the fourth braking torque includes:
determining that the sum of the second braking torque and the fourth braking torque is a second value;
if the second value is larger than or equal to the required braking torque, controlling an energy storage component on a wheel on the inner side of the front axle in the steering direction to provide the second braking torque, and controlling a hub motor on the wheel on the inner side of the front axle in the steering direction to generate a braking torque with a third value; wherein the third value is a difference between the demanded braking torque and the second value;
if the second value is smaller than the required braking torque, controlling an energy storage component on a wheel on the inner side of the front axle in the steering direction to provide the second braking torque, controlling a hub motor on the wheel on the inner side of the front axle in the steering direction to generate a fourth braking torque, and controlling a hydraulic system to generate a fourth braking torque; wherein the fourth value is a difference between the demanded braking torque and the second value.
Optionally, the controlling the electric vehicle to distribute the braking torque of the steering inner wheel of the rear axle according to the third braking torque includes:
if the third braking torque is larger than or equal to the required braking torque, controlling a hub motor of a wheel on the inner steering side of the rear axle to generate the required braking torque;
if the third braking torque is smaller than the required braking torque, controlling a hub motor of a wheel on the inner side of the steering of the rear axle to generate the third braking torque, and controlling the braking torque provided by a hydraulic system to the wheel on the inner side of the steering of the rear axle to be a fifth value; wherein the fifth value is a difference between the demanded braking torque and the third braking torque.
Optionally, before the step of determining steering control over the electric vehicle, the method further includes:
acquiring a steering wheel corner signal and a gear signal of the electric automobile;
determining the type of steering control executed on the electric automobile according to the steering wheel angle signal and the gear signal; wherein the steering control type includes: one of differential steering control and steering control is prevented.
Optionally, the determining, according to the steering wheel angle signal and the gear signal, a type of steering control performed on the electric vehicle includes:
if the steering wheel angle signal is not zero, determining that the type of steering control executed by the electric automobile is steering control;
and if the current gear indicated by the gear signal is a non-neutral gear and the steering wheel angle signal is zero, determining that the type of steering control executed by the electric automobile is differential steering control prevention.
Optionally, after determining the type of steering control performed on the electric vehicle according to the steering wheel angle signal and the gear signal, the method further includes:
acquiring a rotation angular velocity of each wheel of the electric vehicle in a case where it is determined that differential steering prevention control is performed on the electric vehicle;
and according to the rotation angular speed, performing differential steering prevention control on the electric automobile by adjusting the braking torque of each wheel of the electric automobile.
According to another aspect of the present invention, there is provided a steering control apparatus for an electric vehicle, in which each wheel of the electric vehicle is provided with a hub motor, and the hub motors on two front wheels are respectively connected to energy storage components, the apparatus including:
the first acquisition module is used for acquiring the turning angle change rate of a steering wheel under the condition that the electric automobile is determined to be subjected to steering control;
a first determining module, configured to determine a target control mode according to the rotation angle change rate, where the target control mode is: a differential steering control mode or an electric power steering control mode;
the differential steering control module is used for acquiring an energy storage state of an energy storage component under the condition that the target control mode is determined to be the differential steering control mode, wherein the energy storage state is used for indicating whether the energy storage component stores energy or not; acquiring a required braking torque of a wheel on the inner side of a steering wheel and a required driving torque of a wheel on the outer side of the steering wheel; and controlling the electric vehicle to distribute the braking torque of the wheels on the inner side of the steering and the driving torque of the wheels on the outer side of the steering according to the energy storage state so as to generate the required braking torque and the required driving torque.
The embodiment of the invention has the beneficial effects that:
in the scheme, the target control mode of the vehicle steering control is determined through the change rate of the steering angle of the steering wheel, the steering requirement can be met, meanwhile, the target control mode is reasonably selected, and the reduction of energy consumption is facilitated. Furthermore, under the condition that the target control mode is the differential steering control mode, the energy storage state of the energy storage component is combined to control the torque distribution of the electric automobile in the differential steering process, the steering control of the automobile can be realized, and meanwhile, the energy recovery efficiency in the steering control process is improved, so that the driving range of the whole automobile is improved.
Drawings
FIG. 1 is a schematic view of an electric vehicle according to an embodiment of the present invention;
FIG. 2 is a second schematic view of an electric vehicle according to an embodiment of the present invention;
fig. 3 is a flowchart of a steering control method for an electric vehicle according to an embodiment of the present invention;
fig. 4 shows a second flowchart of a steering control method for an electric vehicle according to an embodiment of the present invention;
FIG. 5 shows a flow diagram of system fault detection in accordance with an embodiment of the present invention;
fig. 6 shows a third flowchart of a steering control method for an electric vehicle according to an embodiment of the present invention;
FIG. 7 is a fourth flowchart of a steering control method for an electric vehicle according to an embodiment of the present invention;
fig. 8 is a block diagram showing a configuration of a steering control device for an electric vehicle according to an embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
As shown in fig. 1, an embodiment of the present invention provides a structural schematic diagram of an electric vehicle, where each wheel of the electric vehicle is provided with a hub motor, and the hub motors on two front wheels are connected to energy storage components respectively.
Specifically, a first hub motor belt brake assembly 11 arranged in a left front wheel hub of the electric automobile can be included; a second hub motor with brake assembly 12 disposed within the right front wheel hub; a third hub motor with brake assembly 13 disposed within the left rear wheel hub; a fourth hub motor disposed within the right rear wheel hub carries a brake assembly 14.
And the controller is respectively connected with the first hub motor belt brake assembly 11, the second hub motor belt brake assembly 12, the third hub motor belt brake assembly 13 and the fourth hub motor belt brake assembly 14.
It should be noted that the wheel brake in the above structure is matched with the hub motor, and the working principle of the brake remains unchanged. The arrangement position of the motor is changed from the existing shaft (the middle position of the front shaft or the rear shaft) to a hub motor, so that the existing centralized driving is changed into distributed driving. The distributed hub motors are adopted, the hub motor with the brake assemblies are arranged in the hubs at the wheel ends, a driving shaft and a gearbox are omitted, the number of parts and the weight of the whole automobile can be reduced, the distributed hub motors are adopted to directly drive the wheels, the driving mode of the electric automobile is more flexible, if the electric automobile runs on a low-speed running road section, only two rear wheels can be used as driving wheels, and two front wheels are used as driven wheels to follow, so that the consumption of driving energy can be reduced, and the driving range of the whole automobile can be improved; on the other hand, the distributed hub motors are adopted to directly drive the wheels, so that a driving link can be shortened, the transmission efficiency is improved, the original centralized motor is changed into the hub motor on a single wheel for recovering the braking energy, and the recovery and conversion of the braking energy are more direct and faster.
Optionally, the hub motors in the first hub motor and brake assembly 11 and the second hub motor and brake assembly 12 are excitation motors; the hub motors in the third hub motor belt brake assembly 13 and the fourth hub motor belt brake assembly 14 are permanent magnet motors. In this embodiment, the hub motors of the two rear wheels are permanent magnet synchronous motors, and the two front wheels are asynchronous motors (excitation motors). When the two rear wheels are used as driving wheels, compared with a permanent magnet synchronous motor, the asynchronous wheel hub motor has lower running resistance in the role of a driven wheel, and is beneficial to reducing the energy consumption of the whole vehicle in running, thereby improving the driving range of the electric vehicle. It should be noted that, as another implementation manner, the hub motors of the two rear wheels may also be excited synchronous motors, and the two front wheels may also be permanent magnet motors, so that when the two rear wheels are driven during driving, the energy consumption of the whole vehicle can also be reduced, thereby increasing the driving range of the electric vehicle.
Specifically, as shown in fig. 1, a first energy storage component is connected to the first in-wheel motor belt brake assembly 11, and a second energy storage component is connected to the second in-wheel motor belt brake assembly 12.
In an alternative embodiment, as shown in fig. 1 and 2, the controller is a Vehicle Control Unit 10 (VCU).
Further, as shown in fig. 2, it shows a schematic structural diagram of a brake system of a distributed-drive electric vehicle, the brake system includes:
the electronic stability control module 5 is connected with the first hub motor belt brake assembly 11, the second hub motor belt brake assembly 12, the third hub motor belt brake assembly 13 and the fourth hub motor belt brake assembly 14 through brake pipelines respectively;
a first wheel speed sensor 61 disposed on a left front wheel (LF); a second wheel speed sensor 62 disposed on the right front wheel (RF); a third wheel speed sensor 63 disposed on the left rear wheel (LR); a fourth wheel speed sensor 64 disposed on the right rear wheel (RR); the first wheel speed sensor 61, the second wheel speed sensor 62, the third wheel speed sensor 63 and the fourth wheel speed sensor 64 are respectively connected with the electronic stability control module 5 through hard wires, so that the collected wheel speed signals are transmitted to the electronic stability control module 5.
Electric control booster area braking master cylinder 7, electric control booster area braking master cylinder 7 through the hard line with vehicle control unit 10 is connected to through the brake pipe with electronic stability control module 5 is connected, compares in vacuum booster, and electric control booster can be more accurate control hydraulic braking process, is favorable to improving control accuracy.
The brake pedal 8 and the accelerator pedal 9 are fixed on the periphery of a front panel of a vehicle body cab through bolts, and a displacement sensor 81 on the brake pedal 8 is fixed on the brake pedal through bolts and used for feeding back the stroke change of the brake pedal 8 so as to reflect the braking intention of a driver. The electric control booster with a master cylinder 7 is connected with a brake pedal 8 through a bolt. The displacement sensor 81 connected to the brake pedal 8 and the angle sensor connected to the accelerator pedal 9 are used for acquiring an accelerator pedal signal and a brake pedal signal, and feeding back the acquired signals to the vehicle controller 10.
The steering wheel 15 is provided with a corner sensor, the corner sensor is connected with the steering wheel 15 through a steering column, when the steering wheel 15 rotates, the steering column is driven to rotate, a corner measuring signal of the steering wheel is output through the corner sensor, the corner sensor is electrically connected with the vehicle control unit 10, and the corner measuring signal of the steering wheel is input to the vehicle control unit 10.
As shown in fig. 3, an embodiment of the present invention provides a steering control method for an electric vehicle, including:
step 31, acquiring a turning angle change rate of a steering wheel under the condition that the electric automobile is determined to be subjected to steering control;
in this step, a steering angle measurement signal of the steering wheel is acquired by a steering angle sensor mounted on the steering wheel, and a steering angle change rate is calculated based on the amount of change in the steering angle measurement signal per unit time.
Step 32, determining a target control mode according to the corner change rate, wherein the target control mode is as follows: a differential steering control mode or an electric power steering control mode;
step 33, acquiring an energy storage state of an energy storage component under the condition that the target control mode is determined to be the differential steering control mode, wherein the energy storage state is used for indicating whether the energy storage component stores energy or not; acquiring a required braking torque of a wheel on the inner side of a steering wheel and a required driving torque of a wheel on the outer side of the steering wheel; and controlling the electric vehicle to distribute the braking torque of the wheels on the inner side of the steering and the driving torque of the wheels on the outer side of the steering according to the energy storage state so as to generate the required braking torque and the required driving torque.
It can be understood that, because the steering radii of the front axle and the rear axle are different, the respective required braking torques of the two wheels on the steering inner side are different; the respective required driving torques of the two wheels on the outer side of the steering are different;
in the step, the essence of differential steering is that the rotating speeds of the wheels on the inner side and the outer side of the vehicle are not consistent, the rotating speed of the inner side wheel is reduced, and the rotating speed of the outer side wheel is increased, so that the differential steering is realized. When a differential steering requirement exists, the steering inner side wheel is required to apply braking torque, and the steering outer side wheel is applied with driving torque, so that the purpose of suppressing and reducing the rotating speed of the inner side wheel and enhancing and increasing the rotating speed of the outer side wheel is achieved, and the purpose of differential steering is achieved, and the steering function is achieved. During the execution of the steering control, if the determined target control mode is a differential steering control mode, at least one of the energy storage component and the in-wheel motor is coordinated to provide driving torque by combining the energy storage state of the energy storage component, the required braking torque of the wheels on the inner side of the steering and the required driving torque of the wheels on the outer side of the steering, and at least one of the energy storage component, the in-wheel motor and the hydraulic braking system is coordinated to provide braking torque, so that the distribution of the braking torque of the wheels on the inner side of the steering and the distribution of the driving torque of the wheels on the outer side of the steering are realized to generate the required braking torque and the required driving torque, and the differential steering control is completed.
In the above embodiment, the target control mode of the vehicle steering control is determined according to the steering angle change rate, so that the steering demand can be met, and meanwhile, the target control mode can be reasonably selected, which is beneficial to reducing energy consumption. Furthermore, under the condition that the target control mode is the differential steering control mode, the energy storage state of the energy storage component is combined to control the torque distribution of the electric automobile in the differential steering process, the steering control of the automobile can be realized, and meanwhile, the energy recovery efficiency in the steering control process is improved, so that the driving range of the whole automobile is improved.
Optionally, step 32 further includes:
when the turning angle change rate is larger than or equal to a first threshold value, determining that a target control mode is an electric control power-assisted steering control mode; and when the turning angle change rate is smaller than the first threshold value, determining that the target control mode is differential steering control.
In this step, the rate of change of the steering angle of the steering wheel reflects the speed of the steering demand of the driver. When the turning angle change rate is larger than or equal to the first threshold value, it is indicated that the driver has a relatively urgent steering demand, the differential steering cannot meet the current steering demand, and an electronic power steering control mode needs to be executed, so that the steering demand is quickly realized through electronic power steering. And when the turning angle change rate is smaller than the first threshold value, the steering demand of a driver is slow, and a differential steering control mode can be utilized to recover a part of energy, so that the recovery efficiency of the energy is improved, and the driving range of the whole vehicle is increased.
As shown in fig. 4, as another implementation manner, the step 32 may further include:
step 41, performing steering control;
step 42, judging whether the change rate of the rotation angle is larger than or equal to a preset range A; when the rotation angle change rate is within a preset range a, performing step 43; when the change rate of the rotation angle is greater than the preset range a, step 44 is performed; when the change rate of the rotation angle is smaller than the preset range, performing step 45;
step 43, executing series coordinated steering control, wherein the series coordinated steering control is simultaneously carried out by differential steering and electric control power steering; the respective contribution degree of specific differential steering and automatically controlled power assisted steering accessible are markd and are set up, and such advantage is that, the differential steering can carry out energy recuperation maximize, can retrieve back through the recovery moment of motor with partly energy, reaches energy saving and consumption reduction's purpose, still can reduce electric power assisted steering system operating time.
Step 44, executing electric control power-assisted steering control;
step 45, executing differential steering control;
through the control logic, the differential steering control can be utilized to the maximum extent while the steering control is realized, so that the energy recovery efficiency is improved, and the driving range of the whole vehicle is favorably improved.
In an optional embodiment of the present invention, after the step 32, the method further includes:
under the condition that the target control mode is an electric control power-assisted steering control mode, providing power-assisted steering torque to the electric automobile through an electric control steering engine to complete power-assisted steering of the electric automobile;
and after the power-assisted steering is finished, controlling the electric automobile to enter the differential steering control mode.
In this embodiment, in the electric power steering control mode, firstly, the electric power steering machine provides the electric vehicle with the power steering torque, so that the power steering of the electric vehicle can be completed quickly, the urgent steering requirement of the driver can be met, after the power steering is completed, the electric vehicle is controlled to enter the differential steering control mode, and the vehicle is controlled by performing the differential steering control, so that the steering stability of the vehicle can be maintained.
Further, before the step 31, the method further includes:
and after the vehicle is powered on, controlling the distributed drive type electric automobile to carry out fault detection.
Specifically, fig. 5 shows a detection flow of the fault detection. After completion and passing of the test, the vehicle enters a ready and drive mode. As shown in fig. 5, the detection process includes:
step 51, powering on the vehicle;
step 52, self-checking through the system;
step 53, judging whether the system has abnormal phenomena, if the system is normal, then proceeding to step 44; if the system is judged to be abnormal, step 56 is carried out;
step 54, respectively judging whether the accelerator pedal signal, the brake pedal signal and the steering wheel angle signal are normal, if so, further performing step 55 when judging that the accelerator pedal signal, the brake pedal signal and the steering wheel angle signal have changed signals; if one or more of the accelerator pedal signal, the brake pedal signal and the steering wheel angle signal are judged to be abnormal, judging that a system fault occurs, and performing step 56;
step 55, entering a driving mode;
and step 56, giving an alarm prompt, lighting an alarm lamp and exiting the program.
In the embodiment, before stability control is performed, system fault detection is performed, so that the accuracy of an accelerator pedal signal, a brake pedal signal and a steering wheel corner signal is effectively ensured, and the improvement of the control accuracy is facilitated.
Optionally, before step 31, the method further includes:
acquiring a steering wheel corner signal and a gear signal of the electric automobile;
determining the type of steering control executed on the electric automobile according to the steering wheel angle signal and the gear signal; wherein the steering control type includes: one of differential steering control and steering control is prevented.
Further, the determining the type of steering control performed on the electric vehicle according to the steering wheel angle signal and the gear signal includes:
if the steering wheel angle signal is not zero, determining that the type of steering control executed by the electric automobile is steering control;
and if the current gear indicated by the gear signal is a non-neutral gear and the steering wheel angle signal is zero, determining that the type of steering control executed by the electric automobile is differential steering control prevention.
Specifically, as in fig. 6, the steering control may include:
step 61, acquiring a steering wheel angle signal; after receiving the steering wheel angle signal, the steering demand of the driver is logically judged and then enters a steering executing part.
Step 62, acquiring a current gear signal;
step 63, judging whether the current gear is a neutral gear N; if yes, go to step 67; if not, go to step 64;
step 64, judging whether the corner signal is 0; if yes, go to step 66; if not, go to step 65;
step 65, entering a differential steering prevention control mode;
step 66, entering a person steering control mode;
step 67, judging whether the corner signal is 0; if 0, go to step 66, otherwise go to step 68;
step 68, the current state is maintained and no processing is done.
In the embodiment, whether the steering angle signal is 0 or not needs to be judged, the vehicle gear state needs to be checked before the judgment, if the gear is not in the neutral gear, the steering angle value is looked at, if the gear is 0, the driver does not have a steering demand, and at the moment, the program flows to the steering control mode for preventing the differential speed from causing. If the steering angle signal is not 0, indicating that the driver has a need or intention to steer, steering control is performed by a steering mechanism on the vehicle. If the gear is in the neutral gear, the steering wheel angle is changed and input, the current steering operation is executed by the steering mechanism, and if the steering angle is changed to 0, the program does not process and directly exits from the control.
Further, after determining the type of steering control performed on the electric vehicle according to the steering wheel angle signal and the gear signal, the method further includes:
acquiring a rotation angular velocity of each wheel of the electric vehicle in a case where it is determined that differential steering prevention control is performed on the electric vehicle;
and according to the rotation angular speed, performing differential steering prevention control on the electric automobile by adjusting the braking torque of each wheel of the electric automobile.
Specifically, as shown in fig. 7, the control of preventing the differential steering of the electric vehicle by adjusting the braking torque of each wheel of the electric vehicle according to the rotational angular velocity may include:
step 71, performing a differential steering prevention control;
step 72, judging whether the rotation angular speeds w of the wheels are equal; if yes, ending the control, otherwise, performing step 73;
and 73, acquiring the minimum value of each wheel speed, and applying hydraulic braking torque to other wheels or recovering the braking torque. The other wheels are the rest wheels except the wheel corresponding to the minimum wheel speed, and the recovered torque comprises the recovered torque of the energy storage component and/or the energy recovered torque of the hub motor.
In this embodiment, it is determined that it is currently necessary to prevent the occurrence of the differential steering situation, i.e., to keep the vehicle running straight, through the input of the steering angle of the steering wheel. The method comprises the steps of firstly obtaining the wheel speed of each wheel according to a wheel speed sensor, further judging whether the rotating speed (rotating angular speed) of each wheel is equal or not, if the rotating speed (rotating angular speed) of each wheel is not equal, controlling according to the rotating speed of the lowest wheel, and implementing braking torque or recovery torque control on other wheels with the rotating speed greater than the rotating speed of the lowest wheel, so that the wheel speeds of the wheels are controlled to be equal, and the purpose of preventing vehicle speed from steering is achieved.
In an optional embodiment of the present invention, the step 33 may further include the following two cases:
the first condition is as follows:
controlling an in-wheel motor on a steering outer wheel of the rear axle to provide the required drive torque of the steering outer wheel of the rear axle in the case that the energy storage state indicates that the energy storage component stores energy; and obtaining a first driving torque that is a maximum driving torque of an energy storage member on a wheel on a steering outer side of the front shaft and a first braking torque that is a maximum energy recovery braking torque of hub motors on wheels on a steering inner side of the front shaft and the rear shaft;
controlling the electric automobile to distribute the driving torque of the steering outer wheels of the front axle according to the first driving torque; and controlling the electric automobile to distribute the braking torque of the steering inner side wheels of the front axle and the rear axle according to the first braking torque.
In this embodiment, the energy storage component cannot continue to provide the braking torque to the wheel on the inner side of the front axle in the event of energy storage by the energy storage component, and therefore the driving torque demand of the wheel on the inner side of the front axle must be coordinated with the provision of the in-wheel motor and/or the hydraulic braking system. Furthermore, the driving torque distribution of the steering outer side wheels of the front axle is performed according to the maximum driving torque of the energy storage component on the steering outer side wheels of the front axle, and the distribution of the driving torque is performed by considering the maximum driving torque which can be provided by the energy storage component, so that the electric energy consumption of the in-wheel motor in the steering control process is reduced.
Wherein the controlling the electric vehicle to perform distribution of the drive torque to the steered outer wheels of the front axle in accordance with the first drive torque includes:
controlling an energy storage member on the steering outer side wheels of the front axle to provide the required drive torque of the steering outer side wheels of the front axle if the first drive torque is greater than or equal to the required drive torque;
and if the first driving torque is smaller than the required driving torque, controlling an energy storage component on the outer steering wheel of the front shaft to provide the first driving torque, and controlling a hub motor on the outer steering wheel of the front shaft to generate a driving torque of a difference value between the required driving torque and the first driving torque.
In the embodiment, under the condition that the energy storage component stores energy, the energy storage component provides the maximum driving torque for the steering outer side wheels of the front shaft, and the residual driving torque required by the steering outer side wheels of the front shaft is provided by the hub motor.
Wherein, according to the first braking torque, the control of the electric automobile to distribute the braking torque of the steering inner side wheels of the front axle and the rear axle comprises the following steps:
if the first braking torque is larger than or equal to the required braking torque, controlling hub motors of the steering inner wheels of the front axle and the rear axle to respectively generate the required braking torque;
if the first braking torque is smaller than the required braking torque, the hub motors of the steering inner side wheels of the front axle and the rear axle are controlled to respectively generate the first braking torque, and the braking torques which are respectively provided by the hydraulic system for the steering inner side wheels of the front axle and the rear axle are controlled to be a first value; wherein the first value is a difference between the demanded braking torque and the first braking torque.
In this embodiment, when the energy storage component stores energy, the energy storage component cannot continuously provide the braking torque for the wheel on the inner side of the front axle to be recovered, so that the braking torque demand for the wheel on the inner side of the front axle is preferentially provided by recovering the braking energy of the in-wheel motor, and when the braking energy recovery torque of the in-wheel motor does not meet the braking demand, the hydraulic system is used to supplement the remaining braking torque demand. Thus, energy recovery can be performed to the maximum extent, contributing to energy recovery efficiency in the steering control process.
Case two:
in the case where the energy storage state indicates that the energy storage member is not storing energy, controlling in-wheel motors of the steered outer wheels of the front and rear axles to each generate the required driving torque; and obtaining a second braking torque and a third braking torque; wherein the second braking force is a maximum energy recovery braking torque of an energy storage component on a steering inner wheel of the front axle, and the third braking force is a maximum energy recovery braking torque of an in-wheel motor on a steering inner wheel of the rear axle;
controlling the electric automobile to distribute the braking torque of the steering inner side wheel of the front axle according to the second braking torque; and controlling the electric automobile to distribute the braking torque of the steering inner side wheel of the rear axle according to the third braking torque.
In this embodiment, in the case where the energy storage member does not store energy, the energy storage member cannot continue to supply the drive torque to the steering outer side wheels of the front axle, and therefore the drive torque demand for the steering outer side wheels is supplied from the in-wheel motor. And controlling the electric automobile to distribute the braking torque of the steering inner side wheel of the rear axle according to the maximum energy recovery braking torque of the hub motor on the steering inner side wheel of the rear axle. So as to realize the priority of utilizing the energy storage component and the hub motor to provide the recovery braking torque. In this way, the efficiency of energy recovery is facilitated to be improved.
Wherein the controlling the electric vehicle to distribute the braking torque of the steering inner side wheel of the rear axle according to the third braking torque comprises:
if the third braking torque is larger than or equal to the required braking torque, controlling a hub motor of a wheel on the inner steering side of the rear axle to generate the required braking torque;
if the third braking torque is smaller than the required braking torque, controlling a hub motor of a wheel on the inner side of the steering of the rear axle to generate the third braking torque, and controlling the braking torque provided by a hydraulic system to the wheel on the inner side of the steering of the rear axle to be a fifth value; wherein the fifth value is a difference between the demanded braking torque and the third braking torque.
In the implementation, when the braking energy recovery torque of the hub motor meets the braking requirement, the required braking torque of the steering inner side wheel of the rear axle is generated through the hub motor; when the braking energy recovery torque of the hub motor does not meet the braking requirement, the hydraulic system is used for supplementing the residual braking torque requirement of the wheels on the inner side of the steering of the rear axle. Therefore, energy recovery can be carried out through the hub motor to the maximum extent, and the improvement of the energy recovery efficiency in the steering control process is facilitated.
Wherein the controlling the electric vehicle to distribute the braking torque of the steering inner side wheel of the front axle according to the second braking torque comprises:
if the second braking torque is larger than or equal to the required braking torque, controlling an energy storage component on the steering inner side wheel of the front axle to provide the required braking torque of the steering inner side wheel of the front axle;
if the second braking torque is smaller than the required braking torque, acquiring a fourth braking torque which is the maximum energy recovery torque of a hub motor on a wheel on the steering inner side of the front axle; and controlling the electric automobile to distribute the braking torque of the steering inner side wheel of the front axle according to the second braking torque and the fourth braking torque.
In this embodiment, when the maximum energy recovery braking torque of the energy storage component on the steering inner side wheel of the front axle satisfies the required braking torque of the steering inner side wheel of the front axle, the energy storage component on the steering inner side wheel of the front axle is preferentially controlled to recover the required braking torque of the steering inner side wheel of the front axle; when the maximum energy recovery braking torque of the energy storage component on the wheel on the inner side of the front axle in the steering process does not meet the braking torque required by the wheel on the inner side of the front axle in the steering process, the maximum energy recovery torque of the hub motor on the wheel on the inner side of the front axle in the steering process is further determined, and the braking torque of the front axle on the wheel on the inner side of the front axle in the steering process is distributed according to the maximum energy recovery torque of the hub motor and the maximum energy recovery torque of the energy storage component, so that the energy recovery braking torque is utilized to the maximum extent to perform steering control, and the energy recovery efficiency in the steering control process is improved.
Further, the controlling the electric vehicle to distribute the braking torque of the steering inner wheel of the front axle according to the second braking torque and the fourth braking torque includes:
determining that the sum of the second braking torque and the fourth braking torque is a second value;
if the second value is larger than or equal to the required braking torque, controlling an energy storage component on a wheel on the inner side of the front axle in the steering direction to provide the second braking torque, and controlling a hub motor on the wheel on the inner side of the front axle in the steering direction to generate a braking torque with a third value; wherein the third value is a difference between the demanded braking torque and the second value;
if the second value is smaller than the required braking torque, controlling an energy storage component on a wheel on the inner side of the front axle in the steering direction to provide the second braking torque, controlling a hub motor on the wheel on the inner side of the front axle in the steering direction to generate a fourth braking torque, and controlling a hydraulic system to generate a fourth braking torque;
wherein the fourth value is a difference between the demanded braking torque and the second value.
In this embodiment, when the maximum recovery torque of the in-wheel motor and the maximum recovery torque of the energy storage member do not satisfy the required braking torque of the steered inner wheel of the front axle, the remaining required braking torque of the steered inner wheel of the front axle is complemented by the hydraulic braking system while utilizing the recovery torques of the in-wheel motor and the energy storage member to the maximum extent. Therefore, the energy recovery braking torque is utilized to the maximum extent to carry out steering control, and the energy recovery efficiency in the steering control process is improved.
The embodiment utilizes the essence of the differential steering function to control the braking torque distribution of the wheels at the inner side of the steering and the driving torque distribution of the wheels at the outer side of the steering, and the differential steering function is realized, the efficiency of energy recovery is increased to the maximum extent, the working electric energy consumption of the hub motor is reduced, and better power is provided for the energy conservation and consumption reduction of the electric automobile through a plurality of combined torque distribution modes.
Optionally, as shown in fig. 1 and fig. 2, in an alternative embodiment of the present invention, the first energy storage component includes: the first elastic energy storage device 21 is connected with the first hub motor belt brake assembly 11 through a first transmission shaft 41; and a first electromagnetic clutch 31 for switching the working state of the first elastic energy accumulator 21, wherein the first electromagnetic clutch 31 is disposed between the first transmission shafts 41 and is connected with the vehicle control unit 10 (the connection relationship between the first electromagnetic clutch 31 and the vehicle control unit 10 is not shown in fig. 2).
The second energy storage component includes: a second elastic energy storage device 22, wherein the second elastic energy storage device 22 is connected with the second hub motor belt brake assembly 12 through a second transmission shaft 42; and a second electromagnetic clutch 32 for switching the working state of the second elastic energy storage 22, wherein the second electromagnetic clutch 32 is disposed between the second transmission shafts 42 and connected with the vehicle control unit 10 (the connection relationship between the second electromagnetic clutch 32 and the vehicle control unit 10 is not shown in fig. 2).
Wherein the process of controlling the first and second energy storage components to generate braking torque or provide driving force may include:
controlling the first electromagnetic clutch 31 to attract the first transmission shaft 41 so as to enable the first elastic energy accumulator 21 and the first hub motor belt brake assembly 11 to be communicated; the second electromagnetic clutch 32 is controlled to suck the second transmission shaft 42, so that the second elastic energy storage device 22 is communicated with the second hub motor belt brake assembly 12, partial energy recovery torque is provided by the elastic energy storage device, and the elastic energy storage device converts kinetic energy into elastic energy to store the elastic energy, so that the energy recovery degree is increased. When the driving requirement is met, the elastic potential energy is converted into the driving force, the energy recovery efficiency is effectively improved, the energy consumption of the power battery pack is reduced, and the driving range of the whole vehicle is increased.
Wherein the process of controlling the first and second energy storage components to turn off may comprise:
controlling the first electromagnetic clutch 31 to disconnect the first transmission shaft 41 so as to cut off an energy transmission link between the first elastic energy accumulator 21 and the first in-wheel motor and brake assembly 11; and controlling the second electromagnetic clutch 32 to disconnect the second transmission shaft 42 so as to cut off an energy transmission link between the second elastic energy storage device 22 and the second hub motor and brake assembly 12.
Corresponding to the method embodiment, the embodiment of the invention also provides a steering control device of the electric automobile.
As shown in fig. 8, a steering control device of an electric vehicle is shown, in which each wheel of the electric vehicle is provided with a hub motor, and the hub motors on two front wheels are connected with energy storage components, respectively, the device 800 includes:
a first obtaining module 801, configured to obtain a turning angle change rate of a steering wheel in a case where it is determined that steering control is performed on the electric vehicle;
a first determining module 802, configured to determine a target control mode according to the rotation angle change rate, where the target control mode is: a differential steering control mode or an electric power steering control mode;
a differential steering control module 803, configured to, when it is determined that the target control mode is the differential steering control mode, obtain an energy storage state of an energy storage component, where the energy storage state is used to indicate whether the energy storage component stores energy; acquiring a required braking torque of a wheel on the inner side of a steering wheel and a required driving torque of a wheel on the outer side of the steering wheel; and controlling the electric vehicle to distribute the braking torque of the wheels on the inner side of the steering and the driving torque of the wheels on the outer side of the steering according to the energy storage state so as to generate the required braking torque and the required driving torque.
Optionally, the apparatus further comprises:
the power-assisted steering control module is used for providing power-assisted steering torque to the electric automobile through an electric control steering machine under the condition that the target control mode is an electric control power-assisted steering control mode so as to complete power-assisted steering of the electric automobile; and after the power-assisted steering is finished, controlling the electric automobile to enter the differential steering control mode.
Optionally, the first determining module 802 includes:
the first determining submodule is used for determining that the target control mode is the electric control power-assisted steering control mode when the rotation angle change rate is larger than or equal to a first threshold value;
and a second determination submodule for determining the target control mode as differential steering control when the rate of change in the steering angle is smaller than the first threshold value.
Optionally, the differential steering control module 803 includes:
a first obtaining submodule for obtaining a first driving torque and a first braking torque, in a case where the energy storage state indicates that the energy storage member stores energy, the first driving torque being a maximum driving torque of the energy storage member on a wheel on a steering outer side of the front shaft, and the first braking torque being a maximum energy recovery braking torque of the in-wheel motors on a wheel on a steering inner side of the front shaft and the rear shaft;
the first control submodule is used for controlling the electric automobile to distribute the driving torque of the wheels on the outer side of the steering according to the first driving torque;
and the second control submodule is used for controlling the electric automobile to distribute the braking torque of the steering inner side wheels of the front axle and the rear axle according to the first braking torque.
Optionally, the first control sub-module includes:
a first control unit configured to control an energy storage member on steering outer-side wheels of the front axle to supply the required drive torque to the steering outer-side wheels of the front axle when the first drive torque is greater than or equal to the required drive torque;
a second control unit for controlling the in-wheel motor on the steering outer side wheel of the front axle to generate the required drive torque of the steering outer side wheel of the front axle when the first drive torque is smaller than the required drive torque.
Optionally, the second control sub-module includes:
a third control unit for controlling the in-wheel motors of the steered inner wheels of the front and rear axles to generate the required braking torque, respectively, when the first braking torque is greater than or equal to the required braking torque;
the fourth control unit is used for controlling the hub motors of the wheels at the inner sides of the front axle and the rear axle to respectively generate the first braking torque when the first braking torque is smaller than the required braking torque, and controlling the braking torques which are respectively provided by the hydraulic system for the wheels at the inner sides of the front axle and the rear axle to be a first value;
wherein the first value is a difference between the demanded braking torque and the first braking torque.
Optionally, the differential steering control module further comprises:
a second obtaining submodule for controlling the in-wheel motors of the steered outer wheels of the front and rear axles to each generate the required driving torque, in a case where the energy storage state indicates that the energy storage member does not store energy; and obtaining a second braking torque and a third braking torque;
wherein the second braking force is a maximum energy recovery braking torque of an energy storage component on a steering inner wheel of the front axle, and the third braking force is a maximum energy recovery braking torque of an in-wheel motor on a steering inner wheel of the rear axle;
the third control sub-module is used for controlling the electric automobile to distribute the braking torque of the steering inner side wheel of the front axle according to the second braking torque;
and the fourth control submodule is used for controlling the electric automobile to distribute the braking torque of the wheels on the inner side of the steering of the rear axle according to the third braking torque.
Optionally, the third control sub-module includes:
a fifth control unit for controlling an energy storage component on a steering inner wheel of the front axle to provide the required braking torque of the front axle to the inner wheel if the second braking torque is greater than or equal to the required braking torque;
an obtaining unit configured to obtain a fourth braking torque when the second braking torque is smaller than the required braking torque, the fourth braking torque being a maximum energy recovery torque of a hub motor on a steering inner side wheel of the front axle;
and the sixth control unit is used for controlling the electric automobile to distribute the braking torque of the wheels on the steering inner side of the front axle according to the second braking torque and the fourth braking torque.
Optionally, the sixth control unit is specifically configured to: determining that the sum of the second braking torque and the fourth braking torque is a second value; when the second value is larger than or equal to the required braking torque, controlling an energy storage component on a wheel on the inner side of the front axle in the steering direction to provide the second braking torque, and controlling a hub motor on the wheel on the inner side of the front axle in the steering direction to generate a braking torque of a third value; wherein the third value is a difference between the demanded braking torque and the second value; when the second value is smaller than the required braking torque, controlling an energy storage component on a wheel on the inner side of the front axle in the steering direction to provide the second braking torque, controlling a hub motor on the wheel on the inner side of the front axle in the steering direction to generate a fourth braking torque, and controlling a hydraulic system to generate a fourth braking torque; wherein the fourth value is a difference between the demanded braking torque and the second value.
Optionally, the fourth control sub-module includes:
a seventh control unit for controlling a hub motor of a steering inner wheel of the rear axle to generate the required braking torque when the third braking torque is greater than or equal to the required braking torque;
the eighth control unit is used for controlling the hub motor of the wheel at the inner side of the steering of the rear axle to generate the third braking torque and controlling the braking torque provided by the hydraulic system for the wheel at the inner side of the steering of the rear axle to be a fifth value when the third braking torque is smaller than the required braking torque; wherein the fifth value is a difference between the demanded braking torque and the third braking torque.
Optionally, the apparatus further comprises:
the second acquisition module is used for acquiring a steering wheel corner signal and a gear signal of the electric automobile;
the second determination module is used for determining the steering control type executed on the electric automobile according to the steering wheel angle signal and the gear signal; wherein the steering control type includes: one of differential steering control and steering control is prevented.
Optionally, the second determining module includes:
the third determining submodule is used for determining that the type of steering control executed by the electric automobile is steering control when the steering wheel angle signal is not zero;
and the fourth determining submodule is used for determining that the type of the steering control executed by the electric automobile is the differential steering control when the current gear indicated by the gear signal is a non-neutral gear and the steering wheel angle signal is zero.
Optionally, the apparatus further comprises:
the differential steering prevention control module is used for acquiring the rotation angular speed of each wheel of the electric automobile under the condition that the differential steering prevention control is determined to be executed on the electric automobile; and according to the rotation angular speed, performing differential steering prevention control on the electric automobile by adjusting the braking torque of each wheel of the electric automobile.
The device is a device corresponding to the method embodiment, and all implementation manners in the method embodiment are applicable to the device embodiment, and the same technical effects as the method embodiment can be achieved.
According to the scheme, various steering mode implementation modes are provided according to the input condition of the steering angle and the change rate of the steering angle, such as control strategies of differential steering, electric power steering implemented by a steering engine and series-connection type coordinated steering, the control strategies belong to major innovation appearing for the first time in a steering control system, the function of the differential steering is effectively utilized, the function of keeping a vehicle to perform straight-line running is achieved, the energy consumption of the electric power steering is reduced, the opportunity of energy recovery is increased, and the purpose of increasing the endurance mileage of the electric vehicle is achieved.
The differential steering control is prevented, the vehicle can be guaranteed to run linearly, the energy recovery torque is executed to the maximum extent, the energy recovery force is increased, and the cruising mileage of the vehicle is increased.
Furthermore, the combination of the differential steering and the series coordinated steering control mode reduces the working time of the electric power steering, increases the efficiency of energy recovery, reduces the power consumption of the electric parts and increases the endurance mileage of the electric automobile.
In addition, by adding a control strategy of differential steering, the relation between the electric control power-assisted steering and the differential steering can be further coordinated, the situation that some unstable working conditions are caused by the differential steering is prevented, and the continuous improvement is made for improving the braking energy recovery efficiency and the system safety in the braking process. The elastic energy storage device is added, differential steering can be performed by preferentially selecting the elastic energy storage device, the requirements for energy conservation and consumption reduction are met through combined nested control of driving torque and recovery torque, and driving energy consumption is further reduced.
While the preferred embodiments of the present invention have been described, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.

Claims (14)

1. The steering control method of the electric automobile is characterized in that each wheel of the electric automobile is provided with a hub motor, and the hub motors on two front wheels are connected with energy storage components respectively, and the method comprises the following steps:
acquiring a turning angle change rate of a steering wheel under the condition that the electric automobile is determined to be subjected to steering control;
determining a target control mode according to the corner change rate, wherein the target control mode is as follows: a differential steering control mode or an electric power steering control mode;
under the condition that the target control mode is determined to be the differential steering control mode, acquiring an energy storage state of an energy storage component, wherein the energy storage state is used for indicating whether the energy storage component stores energy or not; acquiring a required braking torque of a wheel on the inner side of a steering wheel and a required driving torque of a wheel on the outer side of the steering wheel; and controlling the electric vehicle to distribute the braking torque of the wheels on the inner side of the steering and the driving torque of the wheels on the outer side of the steering according to the energy storage state so as to generate the required braking torque and the required driving torque.
2. The steering control method according to claim 1, characterized in that, after determining the target control mode based on the rate of change in the steering angle, further comprising:
under the condition that the target control mode is an electric control power-assisted steering control mode, providing power-assisted steering torque to the electric automobile through an electric control steering engine to complete power-assisted steering of the electric automobile;
and after the power-assisted steering is finished, controlling the electric automobile to enter the differential steering control mode.
3. The steering control method according to claim 1, wherein the determining a target control mode according to the rate of change in the steering angle includes:
when the turning angle change rate is larger than or equal to a first threshold value, determining that a target control mode is an electric control power-assisted steering control mode;
and when the turning angle change rate is smaller than the first threshold value, determining that the target control mode is differential steering control.
4. The steering control method according to claim 1, wherein the controlling the electric vehicle to perform distribution of the braking torque to the wheels on the inner side of steering and distribution of the driving torque to the wheels on the outer side of steering to generate the required braking torque and the required driving torque, in accordance with the energy storage state, includes:
controlling an in-wheel motor on a steering outer wheel of the rear axle to provide the required drive torque of the steering outer wheel of the rear axle in the case that the energy storage state indicates that the energy storage component stores energy; and obtaining a first driving torque that is a maximum driving torque of an energy storage member on a wheel on a steering outer side of the front shaft and a first braking torque that is a maximum energy recovery braking torque of hub motors on wheels on a steering inner side of the front shaft and the rear shaft;
controlling the electric automobile to distribute the driving torque of the steering outer wheels of the front axle according to the first driving torque;
and controlling the electric automobile to distribute the braking torque of the steering inner side wheels of the front axle and the rear axle according to the first braking torque.
5. The steering control method according to claim 4, wherein the controlling of the electric vehicle to perform distribution of the drive torque to the steered outer wheels of the front axle in accordance with the first drive torque includes:
controlling an energy storage member on the steering outer side wheels of the front axle to provide the required drive torque of the steering outer side wheels of the front axle if the first drive torque is greater than or equal to the required drive torque;
and if the first driving torque is smaller than the required driving torque, controlling an energy storage component on the outer steering wheel of the front shaft to provide the first driving torque, and controlling a hub motor on the outer steering wheel of the front shaft to generate the driving torque of the difference value between the required driving torque and the first driving torque.
6. The steering control method according to claim 4, wherein the controlling the electric vehicle to distribute the braking torque of the steered inner wheels of the front axle and the rear axle according to the first braking torque includes:
if the first braking torque is larger than or equal to the required braking torque, controlling hub motors of the steering inner wheels of the front axle and the rear axle to respectively generate the required braking torque;
if the first braking torque is smaller than the required braking torque, the hub motors of the steering inner side wheels of the front axle and the rear axle are controlled to respectively generate the first braking torque, and the braking torques which are respectively provided by the hydraulic system for the steering inner side wheels of the front axle and the rear axle are controlled to be a first value;
wherein the first value is a difference between the demanded braking torque and the first braking torque.
7. The steering control method according to claim 1, wherein the controlling the electric vehicle to perform distribution of the braking torque to the wheels on the inner side of steering and distribution of the driving torque to the wheels on the outer side of steering to generate the required braking torque and the required driving torque, in accordance with the energy storage state, includes:
in the case where the energy storage state indicates that the energy storage member is not storing energy, controlling in-wheel motors of the steered outer wheels of the front and rear axles to each generate the required driving torque; and obtaining a second braking torque and a third braking torque;
wherein the second braking force is a maximum energy recovery braking torque of an energy storage component on a steering inner wheel of the front axle, and the third braking force is a maximum energy recovery braking torque of an in-wheel motor on a steering inner wheel of the rear axle;
controlling the electric automobile to distribute the braking torque of the steering inner side wheel of the front axle according to the second braking torque;
and controlling the electric automobile to distribute the braking torque of the steering inner side wheel of the rear axle according to the third braking torque.
8. The steering control method according to claim 7, wherein the controlling the electric vehicle to distribute the braking torque of the steered inner wheel of the front axle according to the second braking torque includes:
if the second braking torque is larger than or equal to the required braking torque, controlling an energy storage component on the steering inner side wheel of the front axle to provide the required braking torque of the steering inner side wheel of the front axle;
if the second braking torque is smaller than the required braking torque, acquiring a fourth braking torque which is the maximum energy recovery torque of a hub motor on a wheel on the steering inner side of the front axle; and controlling the electric automobile to distribute the braking torque of the steering inner side wheel of the front axle according to the second braking torque and the fourth braking torque.
9. The steering control method according to claim 8, wherein the controlling the electric vehicle to distribute the braking torque of the steered inner wheel of the front axle according to the second braking torque and the fourth braking torque includes:
determining that the sum of the second braking torque and the fourth braking torque is a second value;
if the second value is larger than or equal to the required braking torque, controlling an energy storage component on a wheel on the inner side of the front axle in the steering direction to provide the second braking torque, and controlling a hub motor on the wheel on the inner side of the front axle in the steering direction to generate a braking torque with a third value; wherein the third value is a difference between the demanded braking torque and the second value;
if the second value is smaller than the required braking torque, controlling an energy storage component on a wheel on the inner side of the front axle in the steering direction to provide the second braking torque, controlling a hub motor on the wheel on the inner side of the front axle in the steering direction to generate a fourth braking torque, and controlling a hydraulic system to generate a fourth braking torque;
wherein the fourth value is a difference between the demanded braking torque and the second value.
10. The steering control method according to claim 7, wherein the controlling the electric vehicle to distribute the braking torque of the steered inner wheel of the rear axle according to the third braking torque includes:
if the third braking torque is larger than or equal to the required braking torque, controlling a hub motor of a wheel on the inner steering side of the rear axle to generate the required braking torque;
if the third braking torque is smaller than the required braking torque, controlling a hub motor of a wheel on the inner side of the steering of the rear axle to generate the third braking torque, and controlling the braking torque provided by a hydraulic system to the wheel on the inner side of the steering of the rear axle to be a fifth value;
wherein the fifth value is a difference between the demanded braking torque and the third braking torque.
11. The steering control method according to claim 1, characterized in that, before the step of determining steering control over the electric vehicle, the method further comprises:
acquiring a steering wheel corner signal and a gear signal of the electric automobile;
determining the type of steering control executed on the electric automobile according to the steering wheel angle signal and the gear signal; wherein the steering control type includes: one of differential steering control and steering control is prevented.
12. The steering control method according to claim 11, wherein the determining a type of steering control to be performed on the electric vehicle based on the steering wheel angle signal and the shift position signal includes:
if the steering wheel angle signal is not zero, determining that the type of steering control executed by the electric automobile is steering control;
and if the current gear indicated by the gear signal is a non-neutral gear and the steering wheel angle signal is zero, determining that the type of steering control executed by the electric automobile is differential steering control prevention.
13. The steering control method according to claim 11, wherein after determining the type of steering control to be performed on the electric vehicle based on the steering wheel angle signal and the shift position signal, the method further comprises:
acquiring a rotation angular velocity of each wheel of the electric vehicle in a case where it is determined that differential steering prevention control is performed on the electric vehicle;
and according to the rotation angular speed, performing differential steering prevention control on the electric automobile by adjusting the braking torque of each wheel of the electric automobile.
14. The utility model provides an electric automobile's steering control device, its characterized in that, be provided with in-wheel motor on each wheel of electric automobile respectively, and in-wheel motor on two front wheels is connected with energy storage component respectively, the device includes:
the first acquisition module is used for acquiring the turning angle change rate of a steering wheel under the condition that the electric automobile is determined to be subjected to steering control;
a first determining module, configured to determine a target control mode according to the rotation angle change rate, where the target control mode is: a differential steering control mode or an electric power steering control mode;
the differential steering control module is used for acquiring an energy storage state of an energy storage component under the condition that the target control mode is determined to be the differential steering control mode, wherein the energy storage state is used for indicating whether the energy storage component stores energy or not; acquiring a required braking torque of a wheel on the inner side of a steering wheel and a required driving torque of a wheel on the outer side of the steering wheel; and controlling the electric vehicle to distribute the braking torque of the wheels on the inner side of the steering and the driving torque of the wheels on the outer side of the steering according to the energy storage state so as to generate the required braking torque and the required driving torque.
CN202010348017.1A 2020-04-28 2020-04-28 Steering control method and device for electric automobile Active CN113562072B (en)

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