CN113561788A - Traction control method, device and equipment for electric automobile and electric automobile - Google Patents
Traction control method, device and equipment for electric automobile and electric automobile Download PDFInfo
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- CN113561788A CN113561788A CN202010348016.7A CN202010348016A CN113561788A CN 113561788 A CN113561788 A CN 113561788A CN 202010348016 A CN202010348016 A CN 202010348016A CN 113561788 A CN113561788 A CN 113561788A
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- 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
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- 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
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- 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
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- 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
- B60L2240/46—Drive Train control parameters related to wheels
- B60L2240/465—Slip
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- 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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Abstract
The invention discloses a traction control method, a traction control device and traction control equipment of an electric automobile and the electric automobile, wherein each wheel of the electric automobile is respectively provided with a hub motor, and the traction control method comprises the following steps: under the condition that single-wheel traction control on a target wheel is determined, obtaining the braking torque of the target wheel; and controlling the slip ratio of the target wheel to be in a preset slip ratio range by adjusting the wheel cylinder pressure of the target wheel and the driving torque output by the hub motor of the target wheel according to the braking torque. The scheme of the invention can be suitable for the hub motor driven electric automobile, and realizes traction control on the hub motor driven electric automobile.
Description
Technical Field
The invention relates to the technical field of automobiles, in particular to a traction control method, a traction control device and traction control equipment for an electric automobile and the electric automobile.
Background
The traction control system is one of the main control systems of the electric automobile, and the key task of the traction control system is to effectively prevent the wheels from excessively slipping during driving on a slippery road surface so as to obtain good acceleration performance.
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.
Since the reference target of the conventional automobile traction control method is different from that of the in-wheel motor driven distributed electric automobile, it cannot be directly adopted on the in-wheel driven distributed electric automobile. Therefore, a traction control method designed reasonably is required to optimize the traction of the hub-driven distributed electric vehicle and improve the driving safety.
Disclosure of Invention
In order to solve the technical problems, the invention provides a traction control method, device and equipment of an electric automobile and the electric automobile, which are suitable for an electric automobile driven by a hub motor and solve the problem that the reference target of the traditional automobile traction control method is different from that of a distributed electric automobile driven by a hub and cannot be directly adopted on the distributed electric automobile driven by the hub.
According to a first aspect of the present invention, there is provided a traction control method for an electric vehicle, each wheel of the electric vehicle is provided with a hub motor, the method includes:
under the condition that single-wheel traction control on a target wheel is determined, obtaining the braking torque of the target wheel;
and controlling the slip ratio of the target wheel to be in a preset slip ratio range by adjusting the wheel cylinder pressure of the target wheel and the driving torque output by the hub motor of the target wheel according to the braking torque.
Optionally, the method further includes:
when the electric automobile is in a driving working condition, acquiring a first slip ratio of a target wheel of the electric automobile;
determining to perform single-wheel traction control on the target wheel if the first slip ratio is greater than a peak slip ratio.
Optionally, the controlling, according to the braking torque, the slip ratio of the target wheel to be within a preset slip ratio range by adjusting the wheel cylinder pressure of the target wheel and the driving torque output by the hub motor of the target wheel includes:
when the braking torque is equal to zero, reducing the driving torque output by the hub motor of the target wheel;
and when the driving torque of the target wheel is reduced to a first value which enables the slip ratio of the target wheel to be in the preset slip ratio range, controlling the driving torque output by the hub motor of the target wheel to keep the first value unchanged until the driving working condition is finished.
Optionally, the controlling, according to the braking torque, the slip ratio of the target wheel to be within a preset slip ratio range by adjusting the wheel cylinder pressure of the target wheel and the driving torque output by the hub motor of the target wheel includes:
when the braking torque is larger than zero, controlling the wheel cylinder pressure to increase by a preset pressure value;
acquiring a second slip ratio of the target wheel;
when the second slip rate is larger than the peak slip rate, reducing the driving torque output by the hub motor of the target wheel;
and when the driving torque of the target wheel is reduced to a second value which enables the slip ratio of the target wheel to be in the preset slip ratio range, controlling the driving torque output by the hub motor of the target wheel to keep the second value unchanged until the driving working condition is finished.
Optionally, after obtaining the second slip ratio of the target wheel, the method further includes:
and when the second slip rate is in the preset slip rate range, controlling the hub motor of the target wheel to output the currently distributed driving torque.
According to a second aspect of the present invention, there is provided a traction control apparatus for an electric vehicle, each wheel of the electric vehicle being provided with a hub motor, the apparatus comprising:
the device comprises a first obtaining module, a second obtaining module and a control module, wherein the first obtaining module is used for obtaining the braking torque of a target wheel under the condition that single-wheel traction control on the target wheel is determined;
and the control module is used for controlling the slip ratio of the target wheel to be in a preset slip ratio range by regulating the wheel cylinder pressure of the target wheel and the driving torque output by the hub motor of the target wheel according to the braking torque.
Optionally, the apparatus further comprises:
the second acquisition module is used for acquiring a first slip ratio of a target wheel of the electric automobile when the electric automobile is in a driving working condition;
a determination module to determine single-wheel traction control for the target wheel if the first slip rate is greater than a peak slip rate.
Optionally, the control module includes:
the first control submodule is used for reducing the driving torque output by the hub motor of the target wheel when the braking torque is equal to zero;
and the second control submodule is used for controlling the driving torque output by the in-wheel motor of the target wheel to keep the first value unchanged until the driving working condition is finished when the driving torque of the target wheel is reduced to the first value which enables the slip ratio of the target wheel to be in the preset slip ratio range.
According to a third aspect of the present invention, there is provided a traction control device, comprising a processor, a memory, and a computer program stored on the memory and operable on the processor, wherein the processor implements the steps of the traction control method of an electric vehicle as described above when executing the computer program.
According to a fourth aspect of the present invention, there is provided an electric vehicle including the traction control apparatus as described in any one of the above
The embodiment of the invention has the beneficial effects that:
in the scheme, under the condition that single-wheel traction control is determined to be carried out on a target wheel, the braking torque of the target wheel is obtained; and controlling the slip ratio of the target wheel to be in a preset slip ratio range by adjusting the wheel cylinder pressure of the target wheel and the driving torque output by the hub motor of the target wheel according to the braking torque. This scheme can be applicable to the driving electric automobile of in-wheel motor, has realized the traction control to the driving electric automobile of in-wheel motor, has guaranteed the security of driving.
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 flow chart of a traction control method for an electric vehicle according to an embodiment of the present invention;
fig. 4 shows a second flowchart of a traction control method for an electric vehicle according to an embodiment of the invention;
FIG. 5 shows a flow diagram of fault detection for an embodiment of the present invention;
fig. 6 is a third flowchart of a traction control method for an electric vehicle according to an embodiment of the present invention;
fig. 7 is a third schematic structural diagram of an electric vehicle according to an embodiment of the invention;
fig. 8 is a block diagram showing a configuration of a traction 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, the present invention provides a schematic structural diagram of an electric vehicle, in which each wheel of the electric vehicle is provided with a hub motor. The electric automobile specifically comprises a first hub motor belt brake assembly 11 arranged in a left front wheel hub of the electric automobile; 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. Compared with the prior art, the arrangement position of the motor is changed from the original position on the shaft (the middle position of the front shaft or the rear shaft) to the hub motor, so that the original centralized driving is changed into the 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.
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, a schematic structural diagram of a braking system of an electric vehicle is shown, the braking system including:
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 shape and 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 traction control method for an electric vehicle, including:
in this step, traction control is performed individually for a single wheel, and the target wheel refers to a wheel that needs traction control. In the four-wheel electric vehicle, the target wheel is one of a left front wheel, a right front wheel, a left rear wheel, and a right rear wheel.
And step 32, controlling the slip ratio of the target wheel to be in a preset slip ratio range by adjusting the wheel cylinder pressure of the target wheel and the driving torque output by the hub motor of the target wheel according to the braking torque.
The preset slip rate range can be calibrated according to the actual vehicle. Alternatively, the preset slip ratio may include, but is not limited to, a range near the peak slip ratio or an optimal slip ratio range. The slip ratio of the target wheel is kept in a range close to the peak slip ratio, traction control on the wheel is achieved, meanwhile, more energy consumption can be avoided, and the driving range is improved. The peak slip rate can be considered a constant and can be determined by calibration.
In the above embodiment, when single-wheel traction control is triggered for a target wheel, the braking torque of the target wheel is obtained; according to the braking torque, the wheel cylinder pressure of the target wheel and the distribution of the driving torque output by the hub motor of the target wheel are adjusted, the driving torque execution object in the traction control process in the driving process is coordinated, the slip ratio of the target wheel is in the preset slip ratio range, the traction control of the target wheel is realized, and the safety in the driving process is ensured.
Optionally, before step 31, the method may further include:
when the electric automobile is in a driving working condition, acquiring a first slip ratio of a target wheel of the electric automobile;
determining to perform single-wheel traction control on the target wheel if the first slip ratio is greater than a peak slip ratio.
In this embodiment, the peak slip rate is about 20%, and the preset slip rate range may be 17% to 20%. The method specifically comprises the following steps: step 41, acquiring an accelerator pedal signal; step 42, driving force distribution. The driver's braking demand is distributed to the driving force distribution module and then enters the driving force execution section. And 43, judging whether the single-wheel slip rate is greater than the peak slip rate. In the driving force execution process, it is necessary to acquire a slip ratio λ i of each wheel (i ═ 1, 2,3,4, respectively representing four wheels), and determine whether the slip ratio λ i of a single wheel is higher than a peak slip ratio λ p; if the slip ratio lambada i of the single wheel is larger than the peak slip ratio lambdap, triggering a step 44 to carry out single-wheel traction control on the wheel with the excessively high slip ratio; otherwise, step 45 is performed to continue the current driving force distribution until the driving condition is over.
Optionally, the method further comprises:
and after the electric automobile is powered on, carrying out system fault detection.
Specifically, fig. 5 shows a schematic flow chart of fault detection. After the completion and passing of the detection, the electric vehicle enters a ready and driving mode. As shown in fig. 5, the detection process includes:
step 52, performing system self-check;
and step 56, giving an alarm prompt, lighting an alarm lamp and exiting the program.
In the embodiment, before the braking energy recovery control is performed on the electric automobile, the system fault detection is performed, so that the accuracy of the subsequently acquired accelerator pedal signal and the subsequently acquired brake pedal signal is effectively ensured, and the control accuracy is favorably improved.
In an alternative embodiment of the present invention, the step 32 may include the following two cases:
the first condition is as follows:
when the braking torque is equal to zero, reducing the driving torque output by the hub motor of the target wheel;
and when the driving torque of the target wheel is reduced to a first value which enables the slip ratio of the target wheel to be in the preset slip ratio range, controlling the driving torque output by the hub motor of the target wheel to keep the first value unchanged until the driving working condition is finished.
In this embodiment, in the case of no braking torque, it is stated that the slip ratio of a single wheel is too large under the action of the driving force, and the driving force distribution strategy needs to be adjusted, and the driving torque of the wheel (target wheel) with too large slip ratio is first reduced to reduce the slip ratio of the target wheel until the slip ratio of the target wheel is controlled within the preset slip ratio range, so that the wheel can make full use of the adhesion provided by the ground to start smoothly. According to the embodiment, the driving torque of a single electric automobile is reduced, and the rapid and stable starting capability of a single wheel is improved on the basis of ensuring that the current road adhesion is fully utilized by matching with the advanced controllable wheel side driving torque distribution.
The manner of adjusting the driving torque output by the in-wheel motor of the target wheel may include, but is not limited to: the reduction is performed with a preset filter gradient or by reducing a preset value at a time. And the preset filtering gradient and the preset value can be calibrated according to the real vehicle.
Case two:
when the braking torque is larger than zero, controlling the wheel cylinder pressure to increase by a preset pressure value;
acquiring a second slip ratio of the target wheel;
when the second slip rate is larger than the peak slip rate, reducing the driving torque output by the hub motor of the target wheel;
and when the driving torque of the target wheel is reduced to a second value which enables the slip ratio of the target wheel to be in the preset slip ratio range, controlling the driving torque output by the hub motor of the target wheel to keep the second value unchanged until the driving working condition is finished.
In this embodiment, if the slip rate of a single wheel is too large, for example, the first slip rate λ i of the target wheel is greater than the peak slip rate λ P, it is first determined whether the target wheel is assigned with a braking torque, and only if the braking torque of the single wheel is greater than 0, the ESP controller (e.g., the ESP control module in fig. 2) in the electric vehicle braking system can perform pressure adjustment on the wheel cylinder pressure to increase the wheel shift pressure of the target wheel, so as to decrease the slip rate of the target wheel to the second slip rate. The pressure of the wheel cylinder is firstly controlled to increase the preset pressure value, so that the rapid reduction of the slip rate of the target wheel is facilitated, and the slip rate of the target wheel is rapidly reduced from the first slip rate to the second slip rate, thereby improving the slip rate of the wheel and avoiding more energy consumption. Further, if the second slip rate is still larger than the peak slip rate, the driving force distribution strategy of the target wheel is adjusted, the driving moment of the target wheel is reduced, the slip rate of the target wheel is reduced, and the wheels can fully utilize the adhesive force provided by the ground by matching with advanced controllable wheel-side driving moment distribution until the slip rate of the target wheel is controlled within the range of the preset slip rate, so that the effect of quick and stable starting is achieved.
The manner of adjusting the driving torque output by the in-wheel motor of the target wheel may include, but is not limited to: the reduction is performed with a preset filter gradient or by reducing a preset value at a time. The preset filtering gradient and the preset value can be calibrated according to the real vehicle.
Further, after obtaining the second slip ratio of the target wheel, the method may further include:
and when the second slip rate is in the preset slip rate range, controlling the hub motor of the target wheel to output the currently distributed driving torque.
In the above embodiment, if the slip ratio of the target wheel can be maintained within the preset slip ratio range after the wheel cylinder pressure of the target wheel is adjusted by the hydraulic brake system, the in-wheel motor of the target wheel may be continuously operated to output the currently distributed driving torque. The pressure of the wheel cylinder is firstly controlled to rise by the preset pressure value, so that the slip rate of the target wheel is quickly reduced, the problem that the traction control process lasts for a long time is solved, the electric energy consumption is increased, the driving safety of the electric automobile is ensured, and the driving range of the electric automobile is also improved.
Specifically, as shown in fig. 6, a specific flow of the traction control may include the following steps:
and step 61, enabling the single-wheel slip rate lambda i to be too large. For example, the slip ratio λ i of the target wheel is greater than the peak slip ratio, the target wheel being one of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel;
at step 63, the wheel cylinder pressure Pi is increased. The wheel cylinder pressure of the target wheel is increased by adjusting the wheel cylinder pressure by a traction controller, such as an Electronic Stability Program (ESP) 5 in fig. 2.
and step 66, controlling the hub motor of the target wheel to execute the currently distributed braking force.
Further, in the case that an energy storage component is connected to the in-wheel motor of the target wheel, the method further includes:
and when the braking torque is equal to zero, the energy storage component is controlled to be closed so as to block the energy storage component from providing driving force for the target wheel, improve the slip rate of the target wheel and ensure the driving safety.
Based on the above embodiment, the method may further include:
when the wheel cylinder pressure is larger than zero, controlling the wheel cylinder pressure to reduce a preset pressure value;
acquiring a second slip ratio of the target wheel;
and when the second slip rate is greater than the peak slip rate, controlling the energy storage component to be closed so as to block the energy storage component from providing driving force for the target wheel, improving the slip rate of the target wheel and ensuring the driving safety.
Specifically, a first energy storage component is connected to the first hub motor belt brake assembly 11, and a second energy storage component is connected to the second hub motor belt brake assembly 12.
Optionally, as shown in fig. 2 and 7, 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). 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 traction control device of the electric automobile.
As shown in fig. 8, there is shown a traction control apparatus for a distributed-drive electric vehicle, in which a wheel hub motor is provided at each wheel of the electric vehicle, the apparatus 800 includes:
a first obtaining module 801, configured to obtain a braking torque of a target wheel if it is determined that single-wheel traction control is performed on the target wheel;
and the control module 802 is configured to control the slip ratio of the target wheel to be within a preset slip ratio range by adjusting the wheel cylinder pressure of the target wheel and the driving torque output by the hub motor of the target wheel according to the braking torque.
Optionally, the apparatus further comprises:
the second acquisition module is used for acquiring a first slip ratio of a target wheel of the electric automobile when the electric automobile is in a driving working condition;
a determination module to determine single-wheel traction control for the target wheel if the first slip rate is greater than a peak slip rate.
Optionally, the control module 802 includes:
the first control submodule is used for reducing the driving torque output by the hub motor of the target wheel when the braking torque is equal to zero;
and the second control submodule is used for controlling the driving torque output by the in-wheel motor of the target wheel to keep the first value unchanged until the driving working condition is finished when the driving torque of the target wheel is reduced to the first value which enables the slip ratio of the target wheel to be in the preset slip ratio range.
Optionally, the control module 802 may further include:
the third control sub-module is used for controlling the wheel cylinder pressure to increase by a preset pressure value when the braking torque is larger than zero;
the obtaining submodule is used for obtaining a second slip rate of the target wheel;
the fourth control submodule is used for reducing the driving torque output by the hub motor of the target wheel when the second slip rate is larger than the peak slip rate;
and the fifth control submodule is used for controlling the driving torque output by the in-wheel motor of the target wheel to keep the second value unchanged until the driving working condition is finished when the driving torque of the target wheel is reduced to the second value which enables the slip ratio of the target wheel to be in the preset slip ratio range.
Optionally, the control module 802 may further include:
and the sixth control submodule is used for controlling the hub motor of the target wheel to output the currently distributed driving torque when the second slip rate is in the preset slip rate range.
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.
The invention also provides an electric automobile which comprises the traction control device.
The invention also provides a traction control device, which comprises a processor, a memory and a computer program stored on the memory and capable of running on the processor, wherein the processor executes the computer program to realize the steps of the traction control method of the electric automobile.
In the electric automobile driven by the hub motor, the latest traction control strategy needs to be matched, so that the traction control effect can be more effectively improved, otherwise, the stability of the electric automobile is deteriorated, and the driving feeling is deteriorated.
The scheme is that the driving force distribution module distributes the driving force to each wheel to execute. During the execution of the driving force distribution, a single Traction Control System (TCS) Control strategy may be implemented for a single wheel, and a conventional hydraulic modulation controller, such as an Automatic anti-lock braking System (ABS) or an ESP, may continue to operate in the implementation of the TCS Control strategy for the single wheel. More than once, the adjustment of the driving torque of a single wheel can be preferentially considered, the abnormal change of the slip rate of each wheel is determined by analyzing and calculating the slip rate of each wheel, and the traction control is performed on the abnormally changed wheel, so that the slip rate of the single wheel is regulated and controlled, and the effect of stable starting is achieved. The scheme can coordinate the relation between hydraulic braking and motor driving energy by adding a traction control strategy, coordinates a driving torque execution object in the traction control process in the driving process, and continuously improves the purposes of reducing the energy consumption of the driving torque and improving the system safety in the driving process.
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 (10)
1. A traction control method of an electric vehicle, wherein each wheel of the electric vehicle is provided with a hub motor, and the method is characterized by comprising the following steps:
under the condition that single-wheel traction control on a target wheel is determined, obtaining the braking torque of the target wheel;
and controlling the slip ratio of the target wheel to be in a preset slip ratio range by adjusting the wheel cylinder pressure of the target wheel and the driving torque output by the hub motor of the target wheel according to the braking torque.
2. The traction control method of an electric vehicle according to claim 1, further comprising:
when the electric automobile is in a driving working condition, acquiring a first slip ratio of a target wheel of the electric automobile;
determining to perform single-wheel traction control on the target wheel if the first slip ratio is greater than a peak slip ratio.
3. The traction control method of an electric vehicle according to claim 1, wherein the controlling the slip ratio of the target wheel to be in a preset slip ratio range by adjusting a wheel cylinder pressure of the target wheel and a driving torque output by a hub motor of the target wheel according to the braking torque includes:
when the braking torque is equal to zero, reducing the driving torque output by the hub motor of the target wheel;
and when the driving torque of the target wheel is reduced to a first value which enables the slip ratio of the target wheel to be in the preset slip ratio range, controlling the driving torque output by the hub motor of the target wheel to keep the first value unchanged until the driving working condition is finished.
4. The traction control method of an electric vehicle according to claim 1, wherein the controlling the slip ratio of the target wheel to be in a preset slip ratio range by adjusting a wheel cylinder pressure of the target wheel and a driving torque output by a hub motor of the target wheel according to the braking torque includes:
when the braking torque is larger than zero, controlling the wheel cylinder pressure to increase by a preset pressure value;
acquiring a second slip ratio of the target wheel;
when the second slip rate is larger than the peak slip rate, reducing the driving torque output by the hub motor of the target wheel;
and when the driving torque of the target wheel is reduced to a second value which enables the slip ratio of the target wheel to be in the preset slip ratio range, controlling the driving torque output by the hub motor of the target wheel to keep the second value unchanged until the driving working condition is finished.
5. The traction control method of an electric vehicle according to claim 4, wherein after the second slip ratio of the target wheel is obtained, the method further comprises:
and when the second slip rate is in the preset slip rate range, controlling the hub motor of the target wheel to output the currently distributed driving torque.
6. A traction control device of an electric vehicle, wherein each wheel of the electric vehicle is respectively provided with an in-wheel motor, the device is characterized by comprising:
the device comprises a first obtaining module, a second obtaining module and a control module, wherein the first obtaining module is used for obtaining the braking torque of a target wheel under the condition that single-wheel traction control on the target wheel is determined;
and the control module is used for controlling the slip ratio of the target wheel to be in a preset slip ratio range by regulating the wheel cylinder pressure of the target wheel and the driving torque output by the hub motor of the target wheel according to the braking torque.
7. The traction control apparatus for an electric vehicle according to claim 6, further comprising:
the second acquisition module is used for acquiring a first slip ratio of a target wheel of the electric automobile when the electric automobile is in a driving working condition;
a determination module to determine single-wheel traction control for the target wheel if the first slip rate is greater than a peak slip rate.
8. The traction control apparatus of an electric vehicle according to claim 6, wherein the control module includes:
the first control submodule is used for reducing the driving torque output by the hub motor of the target wheel when the braking torque is equal to zero;
and the second control submodule is used for controlling the driving torque output by the in-wheel motor of the target wheel to keep the first value unchanged until the driving working condition is finished when the driving torque of the target wheel is reduced to the first value which enables the slip ratio of the target wheel to be in the preset slip ratio range.
9. A traction control apparatus comprising a processor, a memory, a computer program stored on the memory and executable on the processor, the processor implementing the steps of the traction control method of an electric vehicle according to any one of claims 1 to 5 when executing the computer program.
10. An electric vehicle characterized by comprising the traction control apparatus according to any one of claims 6 to 8.
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| CN202010348016.7A CN113561788A (en) | 2020-04-28 | 2020-04-28 | Traction control method, device and equipment for electric automobile and electric automobile |
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| CN202010348016.7A CN113561788A (en) | 2020-04-28 | 2020-04-28 | Traction control method, device and equipment for electric automobile and electric automobile |
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