CN109435938B

CN109435938B - Brake control method and device

Info

Publication number: CN109435938B
Application number: CN201710751850.9A
Authority: CN
Inventors: 廉玉波; 凌和平; 陈昊; 田果; 李利
Original assignee: BYD Co Ltd
Current assignee: BYD Co Ltd
Priority date: 2017-08-28
Filing date: 2017-08-28
Publication date: 2020-09-15
Anticipated expiration: 2037-08-28
Also published as: CN109435938A

Abstract

The disclosure relates to a brake control method and a brake control device, which relate to the technical field of control, and the method comprises the following steps: when the vehicle speed of the vehicle is greater than or equal to a preset vehicle speed, the current motor working state of the vehicle is obtained, the current motor working state comprises the current working state of each motor of the vehicle, the working state comprises a normal state or a fault state, and a target braking mode corresponding to the current motor working state is determined in multiple preset braking modes, wherein the braking modes are used for controlling front wheels and rear wheels of the vehicle to adopt an electro-hydraulic composite braking mode or a hydraulic braking mode, each braking mode corresponds to one motor working state, and the vehicle is braked according to the target braking mode.

Description

Brake control method and device

Technical Field

The present disclosure relates to the field of control technologies, and in particular, to a brake control method and apparatus.

Background

With the increasing severity of the problems of environmental pollution, non-regeneration and the like caused by traditional energy sources, the contradiction between the continuous increase of world energy demand and the continuous reduction of world energy storage capacity becomes more and more acute, the trend of great development of new energy sources has become inevitable, and electric automobiles and hybrid electric automobiles using new environment-friendly energy sources have become a great trend of automobile technology development. On electric vehicles and hybrid vehicles, the driving motor can also provide braking force for the vehicle when the vehicle decelerates, so that a motor braking system and a traditional hydraulic mechanical braking system jointly form a composite braking system.

The composite brake has the advantage of being capable of recovering brake energy, and when the automobile is decelerated and braked, the motor can be used for generating electricity, so that the brake energy of the automobile is converted into electric energy to be stored, namely regenerative braking. However, in the existing composite braking scheme, how to brake through the composite braking system when a motor fails in the running process is not considered, so that certain potential safety hazards exist.

Disclosure of Invention

The invention aims to provide a brake control method and a brake control device, which are used for providing a brake scheme for a composite brake system when a motor fails so as to solve the problem of potential safety hazard of the composite brake system.

In order to achieve the above object, according to a first aspect of an embodiment of the present disclosure, there is provided a brake control method applied to a vehicle, the method including:

when the vehicle speed of the vehicle is greater than or equal to a preset vehicle speed, acquiring the current motor working state of the vehicle, wherein the current motor working state comprises the current working state of each motor of the vehicle, and the working state comprises a normal state or a fault state;

determining a target braking mode corresponding to the current motor working state in a plurality of preset braking modes; the braking mode is used for controlling front wheels and rear wheels of the vehicle to adopt an electro-hydraulic composite braking mode or a hydraulic braking mode, and each braking mode corresponds to one motor working state;

and braking the vehicle according to the target braking mode.

Optionally, the determining a target braking mode corresponding to the current motor operating state in multiple preset braking modes includes:

when each motor is in the normal state, determining that a target braking mode corresponding to the current motor working state is a first braking mode;

when at least one motor corresponding to a front wheel is in a fault state and each motor corresponding to a rear wheel is in a normal state, determining that a target braking mode corresponding to the current motor working state is a second braking mode;

when at least one motor corresponding to the rear wheel is in a fault state and each motor corresponding to the front wheel is in a normal state, determining that a target braking mode corresponding to the current motor working state is a third braking mode;

and when at least one motor corresponding to the front wheel is in a fault state and at least one motor corresponding to the rear wheel is in the fault state, determining that the target braking mode corresponding to the current motor working state is a fourth braking mode.

Optionally, the first braking mode is: controlling a front shaft and a rear shaft of the vehicle to be in the electro-hydraulic composite braking mode according to a preset proportion;

the second braking mode is as follows: controlling a front axle of the vehicle to be in a hydraulic braking mode and a rear axle of the vehicle to be in the electro-hydraulic composite braking mode according to the preset proportion;

the third braking mode is as follows: controlling a rear axle of the vehicle to be in the hydraulic braking mode and a front axle of the vehicle to be in the electro-hydraulic composite braking mode according to the preset proportion;

the fourth braking mode is as follows: controlling a front axle and a rear axle of the vehicle to be in the hydraulic braking mode according to the preset proportion;

wherein the preset proportion is a distribution proportion for distributing a total braking force of the vehicle to the front and rear axles.

Optionally, the method further includes:

determining a target braking force required by a driver according to the stepping depth of a brake pedal;

determining a first motor braking demand torque according to the target braking force, wherein the first motor braking demand torque is the torque which needs to be provided by a motor braking system when the target braking force is provided by the motor braking system;

determining the maximum braking torque which can be provided currently according to the external characteristics of the motor and the maximum charging power of the battery;

and when the electro-hydraulic compound braking mode is used for braking, controlling the torque provided by the motor braking system and the pressure provided by the hydraulic braking system according to the first motor braking demand torque and the maximum braking torque.

Optionally, the determining the maximum braking torque that can be currently provided according to the external characteristics of the motor and the maximum charging power of the battery includes:

determining the total feedback braking torque of all the motors according to the external motor characteristics of each motor of the vehicle;

determining the maximum feedback braking torque which can be fed back by the battery according to the maximum charging power of the battery;

and taking the minimum value of the total regenerative braking torque and the maximum regenerative braking torque which can be fed back by the battery as the maximum braking torque which can be provided currently.

Optionally, when braking is performed by using the electro-hydraulic compound braking mode, controlling the torque provided by the motor braking system and the pressure provided by the hydraulic braking system according to the first motor braking demand torque and the maximum braking torque includes:

when the first motor braking demand torque is larger than the maximum braking torque, controlling the motor braking system to provide the maximum braking torque, and controlling the hydraulic braking system to provide a first residual pressure, wherein the combined action of the maximum braking torque and the first residual pressure can meet the first motor braking demand torque;

controlling the motor braking system to provide the first motor braking demand torque when the first motor braking demand torque is less than or equal to the maximum braking torque.

Optionally, when the first electric machine braking demand torque is greater than the maximum braking torque, controlling the electric machine braking system to provide the maximum braking torque, and controlling the hydraulic braking system to provide a residual pressure, where a combined action of the maximum braking torque and the residual pressure can meet the first electric machine braking demand torque, includes:

for a target shaft needing to be braked in the electro-hydraulic compound braking mode, when the braking demand torque of a second motor of the target shaft is larger than a first braking torque, controlling the motor corresponding to the target shaft to provide the first braking torque, and controlling the hydraulic braking system to provide a second residual pressure, wherein the combined action of the first braking torque and the second residual pressure can meet the braking demand torque of the second motor;

the target axle is a front axle and/or a rear axle of the vehicle, the second motor braking demand torque is motor braking demand torque which is obtained by distributing the first motor braking demand torque to the target axle according to a preset proportion, and the first braking torque is motor maximum braking torque which is obtained by distributing the maximum braking torque to the target axle according to a preset proportion.

Optionally, the method further includes:

when the vehicle speed of the vehicle is less than a preset vehicle speed, determining a decreasing proportion of the braking torque provided by the motor braking system and an increasing proportion of the braking pressure provided by the hydraulic braking system according to the current vehicle speed, the braking torque provided by the motor braking system, the braking pressure provided by the hydraulic braking system and the total braking torque required by the vehicle;

in the braking process, the braking torque provided by the motor braking system is gradually reduced according to the decreasing proportion, and the braking pressure provided by the hydraulic braking system is gradually increased according to the increasing proportion, so that the combined action of the braking torque provided by the motor braking system and the braking pressure provided by the hydraulic braking system in the braking process always meets the total braking torque, and when the vehicle speed of the vehicle is zero, the braking torque provided by the motor braking system is also zero.

Alternatively, when the ABS is triggered,

the first braking mode is as follows: controlling a front shaft and a rear shaft of the vehicle to be in the electro-hydraulic composite ABS braking mode according to the preset proportion;

the second braking mode is as follows: controlling a front axle of the vehicle to be in a hydraulic ABS braking mode and a rear axle of the vehicle to be in an electro-hydraulic composite ABS braking mode according to the preset proportion;

the third braking mode is as follows: controlling a rear axle of the vehicle to be in the hydraulic ABS braking mode and a front axle of the vehicle to be in the electro-hydraulic composite ABS braking mode according to the preset proportion;

the fourth braking mode is as follows: controlling a front axle and a rear axle of the vehicle to be in the hydraulic ABS braking mode according to the preset proportion;

the preset proportion is a distribution proportion used for distributing the total braking force of the vehicle to the front axle and the rear axle, the electro-hydraulic composite ABS braking mode is a mode of carrying out composite braking by utilizing a motor ABS and a hydraulic ABS, and the hydraulic ABS braking mode is a mode of carrying out braking by utilizing the hydraulic ABS.

According to a second aspect of the embodiments of the present disclosure, there is provided a brake control apparatus applied to a vehicle, the apparatus including:

the system comprises a first obtaining module, a second obtaining module and a control module, wherein the first obtaining module is used for obtaining the current motor working state of the vehicle when the vehicle speed of the vehicle is greater than or equal to a preset vehicle speed, the current motor working state comprises the current working state of each motor of the vehicle, and the working state comprises a normal state or a fault state;

the judging module is used for determining a target braking mode corresponding to the current motor working state in a plurality of preset braking modes; the braking mode is used for controlling front wheels and rear wheels of the vehicle to adopt an electro-hydraulic composite braking mode or a hydraulic braking mode, and each braking mode corresponds to one motor working state;

and the first braking module is used for braking the vehicle according to the target braking mode.

Optionally, the determining module is configured to:

the fourth braking mode is as follows: controlling a front axle and a rear axle of the vehicle to be in the hydraulic braking mode according to a preset proportion;

Optionally, the apparatus further comprises:

the acquisition module is used for determining the target braking force required by the driver according to the stepping depth of the brake pedal;

the processing module is used for determining a first motor braking demand torque according to the target braking force, wherein the first motor braking demand torque is a torque which needs to be provided by a motor braking system when the target braking force is provided by the motor braking system;

the processing module is further used for determining the maximum braking torque which can be provided currently according to the external characteristics of the motor and the maximum charging power of the battery;

the first braking module is further used for controlling the torque provided by the motor braking system and the pressure provided by the hydraulic braking system according to the first motor braking demand torque and the maximum braking torque when the electro-hydraulic compound braking mode is used for braking.

Optionally, the processing module is configured to:

Optionally, the first braking module is configured to:

Optionally, the apparatus further comprises:

the second acquisition module is used for determining a decreasing proportion of the braking torque provided by the motor braking system and an increasing proportion of the braking pressure provided by the hydraulic braking system according to the current vehicle speed, the braking torque provided by the motor braking system, the braking pressure provided by the hydraulic braking system and the total braking torque required by the vehicle when the vehicle speed of the vehicle is less than the preset vehicle speed;

and the second braking module is used for gradually reducing the braking torque provided by the motor braking system according to the decreasing proportion and gradually increasing the braking pressure provided by the hydraulic braking system according to the increasing proportion in the braking process, so that the combined action of the braking torque provided by the motor braking system and the braking pressure provided by the hydraulic braking system always meets the total braking torque in the braking process, and the braking torque provided by the motor braking system is also zero when the vehicle speed of the vehicle is zero.

Alternatively, when the ABS is triggered,

Through the technical scheme, according to the current working state of each motor of the vehicle, the corresponding braking mode is selected to brake the vehicle, and the front wheels and the rear wheels of the vehicle are controlled to brake in the electro-hydraulic composite braking mode or the hydraulic braking mode respectively in different braking modes. Therefore, the braking scheme of the composite braking system is utilized when the motor fails, the problem that the composite braking system has potential safety hazards can be solved, and the safety and the energy utilization rate of the vehicle can be improved on the premise of ensuring that enough braking force is provided for the vehicle.

Additional features and advantages of the disclosure are set forth in the detailed description which follows, and it is understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:

FIG. 1 is a schematic illustration of a braking control method according to an exemplary embodiment;

FIG. 2 is a schematic illustration of another braking control method according to an exemplary embodiment;

FIG. 3 is a schematic illustration of another braking control method according to an exemplary embodiment;

FIG. 4 is a schematic illustration of yet another braking control method according to an exemplary embodiment;

FIG. 5 is a schematic illustration of yet another braking control method according to an exemplary embodiment;

FIG. 6 is a block diagram illustrating a brake control device according to an exemplary embodiment;

FIG. 7 is a block diagram illustrating another brake control device according to an exemplary embodiment;

fig. 8 is a block diagram illustrating yet another brake control apparatus according to an exemplary embodiment.

Detailed Description

Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.

In the present disclosure, where directional terms such as "upper, lower, left, right, front, and rear" are used without making a contrary explanation, it is to be noted that the above directional terms are used only for explaining and explaining the present disclosure, and are not used for limitation, and generally correspond to upper, lower, left, right, front, and rear of a vehicle.

Before describing the braking control method and device provided by the present disclosure, an application scenario related to various embodiments of the present disclosure is first described. The application scene is any electric automobile using electric power as an energy source, and is not limited to a pure electric automobile or a hybrid automobile, wherein wheels of the electric automobile are divided into a front wheel and a rear wheel, and the front wheel and the rear wheel are respectively connected with a front shaft and a rear shaft of the electric automobile.

FIG. 1 is a schematic illustration of a braking control method, shown in FIG. 1, applied to a vehicle, according to an exemplary embodiment, the method including:

step 101, when the vehicle speed of the vehicle is greater than or equal to a preset vehicle speed, obtaining the current motor working state of the vehicle, wherein the current motor working state comprises the current working state of each motor of the vehicle, and the working state comprises a normal state or a fault state.

For example, during the driving process of the vehicle, the speed of the vehicle is always monitored, and the current working state of each motor of the vehicle is acquired on the premise that the speed of the vehicle is greater than or equal to the preset speed. The preset vehicle speed can be 5km/h, and the working state comprises a normal state or a fault state. Each wheel of the vehicle is provided with a respective electric motor, the operating states of each of which are independent of each other, since it is possible that one or more of the electric motors may fail. Therefore, the current working state of each motor of the vehicle can be respectively detected through measuring devices such as a temperature sensor and a rotating speed sensor, and the working state of each motor can also be monitored in real time through a main control system of the vehicle.

And 102, determining a target braking mode corresponding to the current motor working state in a plurality of preset braking modes. The braking mode is used for controlling the front wheels and the rear wheels of the vehicle to adopt an electro-hydraulic composite braking mode or a hydraulic braking mode, and each braking mode corresponds to one motor working state.

And 103, braking the vehicle according to the target braking mode.

Illustratively, a target braking mode appropriate for the current motor operating state is selected based on the current motor operating state of each of the vehicles. Each front wheel of the vehicle is connected with the front shaft of the vehicle, and each rear wheel of the vehicle is connected with the rear shaft of the vehicle, so that an electro-hydraulic composite braking mode or a hydraulic braking mode can be selected for the front shaft or the rear shaft according to the working states of the corresponding motors of the front wheels and the rear wheels.

In conclusion, according to the present disclosure, according to the current working state of each motor of the vehicle, the corresponding braking mode is selected to brake the vehicle, and the front wheels and the rear wheels of the vehicle are controlled by different braking modes to brake in the electro-hydraulic composite braking mode or the hydraulic braking mode respectively. Therefore, the braking scheme of the composite braking system is utilized when the motor fails, the problem that the composite braking system has potential safety hazards can be solved, and the safety and the energy utilization rate of the vehicle can be improved on the premise of ensuring that enough braking force is provided for the vehicle.

FIG. 2 is a schematic diagram illustrating another braking control method according to an exemplary embodiment, as shown in FIG. 2, step 102 includes:

and step 1021, when each motor is in a normal state, determining that the target braking mode corresponding to the current motor working state is the first braking mode.

And step 1022, when at least one motor corresponding to the front wheel is in a fault state and each motor corresponding to the rear wheel is in a normal state, determining that the target braking mode corresponding to the current motor working state is the second braking mode.

And 1023, when at least one motor corresponding to the rear wheel is in a fault state and each motor corresponding to the front wheel is in a normal state, determining that the target braking mode corresponding to the current motor working state is a third braking mode.

And step 1024, when at least one motor corresponding to the front wheel is in a fault state and at least one motor corresponding to the rear wheel is in the fault state, determining that the target braking mode corresponding to the current motor working state is the fourth braking mode.

For example, the wheels of the vehicle (the number of the wheels is usually 4, but may also be 6 or 8, etc., and the present disclosure is not limited thereto) are connected to the front axle or the rear axle to distinguish the front wheels from the rear wheels, because the braking force of the left wheel and the right wheel on the front axle is required to be the same during the braking process of the vehicle, and the braking force of the left wheel and the right wheel on the rear axle is the same, so that the vehicle can not shake or deflect due to the inconsistency of the left and right braking effects during the braking process. Further, the braking force on the front axle and the braking force on the rear axle are braked according to the preset proportion according to the difference of power distribution, so that the vehicle can be smoothly braked. Therefore, according to the working conditions of the front and rear wheels of the vehicle corresponding to the motors, the target braking mode can be classified into:

each motor of the vehicle is in a corresponding first braking mode in a normal state, and each motor of the vehicle can brake a corresponding wheel normally at the moment.

And at least one motor in the motors corresponding to the front wheels of the vehicle is in a fault state, and the motors corresponding to the rear wheels of the vehicle are in a second braking mode corresponding to a normal state, wherein at the moment, the front wheels of the vehicle cannot be braked by using the motors.

And at least one motor corresponding to the rear wheels of the vehicle is in a fault state, and the front wheels of the vehicle correspond to a third brake mode corresponding to the motors in a normal state, and at the moment, the rear wheels of the vehicle cannot be braked by the motors.

And when at least one of the motors corresponding to the front wheels and the rear wheels of the vehicle is in a fault state, the corresponding fourth brake mode is adopted, and at the moment, the vehicle can only be braked through a hydraulic system.

According to the scheme, the four braking modes are set, the braking modes suitable for the current states of the front wheel and/or the rear wheel can be selected according to the current working states of the front wheel and the rear wheel of the vehicle, and the consumption of energy is saved by fully utilizing the motor braking on the premise that sufficient braking force is provided for the vehicle.

Wherein the first braking mode is: and controlling a front shaft and a rear shaft of the vehicle to be in an electro-hydraulic composite braking mode according to a preset proportion.

The second braking mode is as follows: and controlling a front axle of the vehicle to be in a hydraulic braking mode and a rear axle of the vehicle to be in an electro-hydraulic composite braking mode according to a preset proportion.

The third braking mode is: and controlling a rear axle of the vehicle to be in a hydraulic braking mode and a front axle of the vehicle to be in an electro-hydraulic composite braking mode according to a preset proportion.

The fourth braking mode is: and controlling a front axle and a rear axle of the vehicle to be in a hydraulic braking mode according to a preset proportion.

The preset proportion is a distribution proportion for distributing the total braking force of the vehicle to the front axle and the rear axle, because the braking forces of the left wheel and the right wheel on the front axle are required to be the same and the braking forces of the left wheel and the right wheel on the rear axle are also required to be the same in order to prevent vehicle unbalance caused by different braking forces of the left wheel and the right wheel, so that the braking forces can be distributed according to the front axle and the rear axle only when the braking forces are shared, and the distribution braking forces of the left wheel and the right wheel of the front axle and the rear axle are the same by default.

For example, the preset proportion is a distribution proportion of the total braking force of the vehicle to the front axle and the rear axle, namely, the ratio of the braking force of the front axle of the vehicle to the braking force of the rear axle of the vehicle, and the distribution process can be illustrated by the following formula:

Pressure_F＝a*Total_Pressure

Pressure_R＝b*Total_Pressure

where a and b are both positive numbers, a + b is 1, Pressure _ F is the braking force of the front axle of the vehicle, Pressure _ R is the braking force of the rear axle of the vehicle, and Total _ Pressure is the Total braking force of the vehicle. For example, the preset ratio may be set to 7: 3, i.e. a is 0.7 and b is 0.3, which ratio can be considered as an ideal ratio of the front axle and rear axle brake force distribution. In each target braking mode, the ratio of the braking force of the front axle to the braking force of the rear axle may be 7: 3.

the vehicle is provided with a motor braking system and a hydraulic braking system, wherein the electro-hydraulic composite braking mode is to select the motor braking system for braking, and when the feedback torque provided by the motor braking system is not enough to meet the target braking force demand, the hydraulic braking system provides the residual braking force. The hydraulic braking mode is that the hydraulic braking system is completely used for braking.

Above-mentioned scheme comes the braking power of distribution for front axle and rear axle through setting up the proportion of predetermineeing, can make the total braking force of vehicle distribute the vehicle front and rear axle on rationally for the vehicle can reach the braking effect of preferred, and the same braking force is distributed to the left and right sides two-wheeled simultaneously to front axle or rear axle, can make the braking process of vehicle more steady.

FIG. 3 is a schematic diagram illustrating another braking control method according to an exemplary embodiment, as shown in FIG. 3, further including:

and step 104, determining the target braking force required by the driver according to the stepping depth of the brake pedal.

For example, the tread depth may be collected by providing a sensor on the brake pedal, such as a pressure sensor or a distance sensor, and according to the tread depth, the target braking force required by the driver may be obtained in a preset relation table, which may be measured in advance during the design process of the vehicle and records the target braking forces corresponding to different tread depths. And the target braking force required by different treading depths can be calculated according to a preset functional relation. The acquired target braking force can be acquired and transmitted through the main control of the vehicle.

And 105, determining a first motor braking demand torque according to the target braking force, wherein the first motor braking demand torque is the torque which needs to be provided by the motor braking system when the target braking force is provided by the motor braking system.

And step 106, determining the maximum braking torque which can be currently provided according to the external characteristics of the motor and the maximum charging power of the battery.

For example, a vehicle is provided with a motor braking system and a hydraulic braking system, the motor braking system has the advantages of short response time and battery charging during braking, so that the motor braking system should be preferentially selected when the motor corresponding to the wheel is in a normal state during braking. The first motor braking demand torque is torque that the motor braking system needs to provide when the motor braking system provides the target braking force completely without limiting the braking capability of the motor braking system. Therefore, it is necessary to determine the maximum braking torque that the motor braking system can provide, based on the external characteristics of the motor and the maximum charging power of the battery. The external characteristics of the motor are determined by the motor, and the maximum charging power of the battery determines the upper torque limit for charging the battery when the motor is braked.

Step 103 comprises: when the electro-hydraulic compound braking mode is used for braking, the torque provided by the motor braking system and the pressure provided by the hydraulic braking system are controlled according to the first motor braking demand torque and the maximum braking torque.

According to the scheme, whether the maximum braking torque provided by the motor can meet the pure motor braking demand torque can be determined by determining the maximum braking torque which can be provided currently and the first motor braking demand torque, so that the torque provided by the motor braking can be utilized to the maximum extent when the electric-hydraulic composite braking mode is used for braking, the maximum recovered braking energy of the motor braking can be fully utilized, and the energy consumption is saved.

FIG. 4 is a schematic diagram illustrating yet another braking control method according to an exemplary embodiment, as shown in FIG. 4, step 106 includes:

step 1061, determining the total regenerative braking torque of all the motors according to the external motor characteristics of each motor of the vehicle.

Step 1062, determining the maximum regenerative braking torque that can be fed back by the battery according to the maximum charging power of the battery.

In step 1063, the minimum value of the total regenerative braking torque and the maximum regenerative braking torque that can be fed back by the battery is used as the maximum braking torque that can be currently provided.

For example, the total regenerative braking torque of the electric machine is:

T_reg＝(T_F_min+T_R_min)*2

wherein, T _ reg is the maximum torque which can be provided by the motor braking system at present, T _ F _ min is the minimum torque in a plurality of maximum torques which can be provided by a plurality of motors corresponding to the front wheels of the vehicle, and T _ R _ min is the minimum torque in a plurality of maximum torques which can be provided by a plurality of motors corresponding to the rear wheels of the vehicle.

The maximum feedback braking torque which can be fed back by the battery is as follows:

T_b＝R*3600P_blimt/v/η_z

wherein, T_bFor maximum regenerative braking torque, R is the radius of the vehicle wheel, P_blimtMaximum charging power for the battery, v current vehicle speed, η_zFor transmission efficiency.

T _ reg and T_bMinimum value of (1) asThe maximum braking torque that can currently be provided.

According to the scheme, the method for determining the maximum braking torque provided by the motor is provided, so that after the maximum braking torque provided by the motor is obtained, whether the maximum braking torque provided by the motor can meet the torque required by pure motor braking is determined, and therefore when the braking is carried out in an electro-hydraulic composite braking mode, the torque provided by the motor braking can be utilized to the maximum extent, the maximum recovery of braking energy is achieved by fully utilizing the motor braking, and the energy consumption is saved.

Optionally, step 103 includes:

when the first motor braking demand torque is larger than the maximum braking torque, the motor braking system is controlled to provide the maximum braking torque, the hydraulic braking system is controlled to provide first residual pressure, and the first motor braking demand torque can be met under the combined action of the maximum braking torque and the first residual pressure.

And controlling the motor braking system to provide the first motor braking demand torque when the first motor braking demand torque is less than or equal to the maximum braking torque.

For example, when the target braking mode is the electro-hydraulic compound braking mode, the motor braking system is preferentially selected to perform braking, and when the first motor braking demand torque is greater than the maximum braking torque, that is, the motor braking system is not currently sufficient to meet the demand of the target braking force, at this time, the motor braking system is controlled to provide the maximum braking torque, and the hydraulic braking system is controlled to provide the first residual pressure.

According to the scheme, whether the maximum braking torque provided by the motor can meet the pure motor braking requirement torque can be determined by determining the maximum braking torque which can be provided by the current motor and the first motor braking requirement torque, and when the maximum braking torque provided by the motor cannot meet the pure motor braking requirement torque, the hydraulic braking system provides braking pressure to supplement the part of the braking torque which is deficient in the maximum braking torque provided by the motor compared with the first motor braking requirement torque, so that when the electro-hydraulic compound braking mode is used for braking, the torque provided by motor braking can be utilized to the maximum extent, the maximum recovered braking energy of the motor braking can be fully utilized, and the energy consumption is saved.

Optionally, when the first electric machine braking demand torque is greater than the maximum braking torque, controlling the electric machine braking system to provide the maximum braking torque, and controlling the hydraulic braking system to provide the residual pressure, where the combined action of the maximum braking torque and the residual pressure can meet the first electric machine braking demand torque, including:

for a target shaft needing to be braked in an electro-hydraulic composite braking mode, when the braking demand torque of a second motor of the target shaft is larger than the first braking torque, the motor corresponding to the target shaft is controlled to provide the first braking torque, a hydraulic braking system is controlled to provide second residual pressure, and the combined action of the first braking torque and the second residual pressure can meet the braking demand torque of the second motor.

The target axle is a front axle and/or a rear axle of the vehicle, the second motor braking demand torque is the motor braking demand torque which is obtained by distributing the first motor braking demand torque to the target axle according to a preset proportion, and the first braking torque is the motor maximum braking torque which is obtained by distributing the maximum braking torque to the target axle according to a preset proportion.

The preset ratio is 7: 3 for illustration:

Hydraumatic_F＝0.7*Total_Breaking_Pressure*(1-Motor_Torque_F/Total_Breaking_Torque)

Hydraumatic_R＝0.3*Total_Breaking_Pressure*(1-Motor_Torque_R/Total_Breaking_Torque)

the hydraulic braking system comprises a hydraulic braking system, a Motor, a Torque converter, a transmission and a transmission, wherein the hydraulic _ F is a second residual Pressure of a front axle of the vehicle, the hydraulic _ R is a second residual Pressure of a rear axle of the vehicle, the Total _ braking _ Pressure is a braking force required by the hydraulic braking system when a target braking force is completely provided by the hydraulic braking system, the 0.7 Motor _ Torque _ F is a first braking Torque of the front axle of the vehicle, the 0.3 Motor _ Torque _ R is a first braking Torque of the rear axle of the vehicle, and the Total _ braking _ Torque is a first Motor braking required Torque. 0.7 Total _ Breaking _ Torque is the second motor braking demand Torque of the front axle of the vehicle, and 0.3 Total _ Breaking _ Torque is the second motor braking demand Torque of the rear axle of the vehicle.

The scheme provides a specific method for distributing the braking force for the front axle and the rear axle, the total braking force of the vehicle can be reasonably distributed to the front axle and the rear axle of the vehicle by setting the preset proportion, so that the vehicle can achieve a better braking effect, and meanwhile, the same braking force is distributed to the left wheel and the right wheel of the front axle or the rear axle, so that the braking process of the vehicle is more stable.

FIG. 5 is a schematic diagram illustrating yet another braking control method according to an exemplary embodiment, as shown in FIG. 5, further including:

and 107, when the vehicle speed of the vehicle is less than the preset vehicle speed, determining a decreasing proportion of the braking torque provided by the motor braking system and an increasing proportion of the braking pressure provided by the hydraulic braking system according to the current vehicle speed, the braking torque provided by the motor braking system, the braking pressure provided by the hydraulic braking system and the total braking torque required by the vehicle.

And 108, in the braking process, gradually reducing the braking torque provided by the motor braking system according to a decreasing proportion, and gradually increasing the braking pressure provided by the hydraulic braking system according to an increasing proportion, so that the combined action of the braking torque provided by the motor braking system and the braking pressure provided by the hydraulic braking system in the braking process always meets the total braking torque, and when the vehicle speed of the vehicle is zero, the braking torque provided by the motor braking system is also zero.

For example, if the driving speed is low and the driving road adhesion coefficient is low, the problem that the motor is reversely rotated due to too large road feedback torque is caused, and the motor is damaged, and in order to avoid the problem, when the vehicle speed is lower than the preset vehicle speed, the change rules of the braking torque provided by the motor braking system and the braking pressure provided by the hydraulic braking system are determined according to the current vehicle speed, the braking torque currently provided by the motor braking system, the braking pressure currently provided by the hydraulic braking system, and the total braking torque required by the vehicle. The change rule ensures that the vehicle can meet the requirement of target braking force all the time under the combined action of the motor braking system and the hydraulic braking system in the braking process, and simultaneously can ensure that the feedback torque of the motor braking system can also be reduced to zero before the vehicle speed is reduced to zero or at the moment when the vehicle speed is reduced to zero. The decreasing proportion and the increasing proportion can be obtained in advance through experiments and measurement in the design process of the vehicle, can be set according to percentages, such as the decreasing proportion is decreased by p% every time, the increasing proportion is increased by q% every time, a stepping interval can also be set, such as the decreasing proportion is decreased by m every time and the increasing proportion is increased by n every time, a function conforming to an actual scene can be fitted through a large amount of measurement data, and the real-time decreasing proportion and the increasing proportion are determined by taking the current vehicle speed, the performances of a motor braking system and a hydraulic braking system and the target braking force as parameters.

According to the scheme, when the vehicle runs at a low speed, the braking torque provided by the motor braking system is controlled to gradually decrease, and the braking pressure provided by the hydraulic braking system gradually increases, so that when the vehicle stops, the braking torque provided by the motor braking system is zero, the damage to the motor caused by motor reversal due to motor feedback braking can be avoided when the vehicle runs at the low speed, and the safety of the vehicle can be improved.

Alternatively, when an ABS (English: Antilock Brake System, Chinese: Antilock Brake System) is triggered,

the first braking mode is: and controlling a front axle and a rear axle of the vehicle to be in an electro-hydraulic composite ABS braking mode according to a preset proportion.

The second braking mode is as follows: according to the preset proportion, the front axle of the vehicle is controlled to be in a hydraulic ABS braking mode, and the rear axle of the vehicle is controlled to be in an electro-hydraulic composite ABS braking mode.

The third braking mode is: according to the preset proportion, the rear axle of the vehicle is controlled to be in a hydraulic ABS braking mode, and the front axle of the vehicle is controlled to be in an electro-hydraulic composite ABS braking mode.

The fourth braking mode is: and controlling a front axle and a rear axle of the vehicle to be in a hydraulic ABS braking mode according to a preset proportion.

The preset proportion is a distribution proportion used for distributing the total braking force of the vehicle to the front axle and the rear axle, the electro-hydraulic composite ABS braking mode is a mode of carrying out composite braking by using a motor ABS and a hydraulic ABS, and the hydraulic ABS braking mode is a mode of carrying out braking by using the hydraulic ABS.

Different from the braking mode when the ABS is not started, for the electro-hydraulic composite ABS braking mode, the motor ABS is triggered first, the motor ABS is controlled to increase the feedback torque for braking, when the feedback torque of the motor ABS is increased to the maximum feedback torque which can be provided by the motor and is smaller than the first motor braking demand torque, the motor ABS is closed, and then the hydraulic ABS is triggered for braking. And the hydraulic ABS braking mode is to trigger the hydraulic ABS to brake.

For example, in emergency braking of a vehicle, the ABS is triggered by providing sufficient braking force to the vehicle while maximizing the adhesion of the wheels to the ground and maintaining the steering capability of the vehicle. Compared with the braking under the normal state, the corresponding target braking mode after the ABS is triggered can control the front axle and the rear axle to brake in an electro-hydraulic composite ABS braking mode or a hydraulic ABS braking mode according to the working states of the corresponding motors of the front wheels and the rear wheels of the vehicle. Specifically, the first brake mode is an electro-hydraulic composite ABS brake mode for both the front axle and the rear axle, i.e., the motor ABS is triggered first, at this time, the hydraulic ABS does not work, the feedback torque provided by the motor ABS rises continuously, if the feedback torque has met the current target brake force (the brake force generated by the maximum torque that can be currently fed back by the motor is greater than or equal to the target brake force), the braking is completed, if the feedback torque cannot meet the current target brake force (the brake force generated by the maximum torque that can be currently fed back by the motor is less than the target brake force), the motor ABS continuously increases the feedback torque until the maximum torque that can be currently fed back by the motor ABS is triggered, the hydraulic ABS is then triggered, the motor ABS is withdrawn, at this time, the motor ABS provides the maximum torque that can be currently fed. The second brake mode is that the rear axle selects the electro-hydraulic composite ABS brake mode, and the front axle selects the hydraulic ABS brake mode, namely the hydraulic ABS is completely used for providing braking force. The third brake mode is that the front axle selects an electro-hydraulic composite ABS brake mode, and the rear axle selects a hydraulic ABS brake mode. The fourth braking mode is a hydraulic ABS braking mode for both the front axle and the rear axle.

By setting the four ABS braking modes, the ABS braking modes suitable for the current states of the front wheels and/or the rear wheels can be selected respectively according to the current working states of the front wheels and the rear wheels of the vehicle under the condition of triggering the ABS, and the consumption of energy is saved by fully utilizing the ABS braking of the motor on the premise of ensuring that enough braking force is provided for the vehicle.

Fig. 6 is a block diagram illustrating a brake control apparatus according to an exemplary embodiment, and as shown in fig. 6, the apparatus 200 includes:

the first obtaining module 201 is configured to obtain a current motor working state of the vehicle when a vehicle speed of the vehicle is greater than or equal to a preset vehicle speed, where the current motor working state includes a current working state of each motor of the vehicle, and the working state includes a normal state or a fault state.

The determining module 202 is configured to determine a target braking mode corresponding to a current motor operating state in multiple preset braking modes. The braking mode is used for controlling the front wheels and the rear wheels of the vehicle to adopt an electro-hydraulic composite braking mode or a hydraulic braking mode, and each braking mode corresponds to one motor working state.

And the first braking module 203 is used for braking the vehicle according to the target braking mode.

Optionally, the determining module 202 is configured to:

and when each motor is in the normal state, determining that the target braking mode corresponding to the current motor working state is the first braking mode.

And when at least one motor corresponding to the front wheel is in a fault state and each motor corresponding to the rear wheel is in a normal state, determining that the target braking mode corresponding to the current motor working state is the second braking mode.

And when at least one motor corresponding to the rear wheel is in a fault state and each motor corresponding to the front wheel is in a normal state, determining that the target braking mode corresponding to the current motor working state is a third braking mode.

And when at least one motor corresponding to the front wheel is in a fault state and at least one motor corresponding to the rear wheel is in the fault state, determining that the target braking mode corresponding to the current motor working state is the fourth braking mode.

By setting the four braking modes, the braking modes suitable for the current states of the front wheel and/or the rear wheel can be selected according to the current working states of the front wheel and the rear wheel of the vehicle, and the consumption of energy is saved by fully utilizing the motor braking on the premise of ensuring that enough braking force is provided for the vehicle.

Optionally, the first braking mode is: and controlling a front shaft and a rear shaft of the vehicle to be in an electro-hydraulic composite braking mode according to a preset proportion.

Wherein the preset ratio is a distribution ratio for distributing the total braking force of the vehicle to the front axle and the rear axle.

The braking force distribution of the front axle and the rear axle is achieved by setting the preset proportion, the total braking force of the vehicle can be reasonably distributed to the front axle and the rear axle of the vehicle, the vehicle can achieve a better braking effect, and meanwhile the same braking force is distributed to the left wheel and the right wheel of the front axle or the rear axle, so that the braking process of the vehicle is more stable.

Fig. 7 is a block diagram illustrating another brake control apparatus according to an exemplary embodiment, and as shown in fig. 7, the apparatus 200 further includes:

and the acquisition module 204 is used for determining the target braking force required by the driver according to the stepping depth of the brake pedal.

The processing module 205 is configured to determine a first motor braking demand torque according to the target braking force, where the first motor braking demand torque is a torque that the motor braking system needs to provide when the motor braking system provides the target braking force.

The processing module 205 is further configured to determine a maximum braking torque that can be currently provided according to the off-motor characteristics and the maximum charging power of the battery.

The first braking module 203 is further configured to control torque provided by the motor braking system and pressure provided by the hydraulic braking system according to the first motor braking demand torque and the maximum braking torque when the electro-hydraulic compound braking mode is used for braking.

Optionally, the processing module 205 is configured to:

the total regenerative braking torque of all the electric machines is determined based on the off-machine characteristics of each electric machine of the vehicle.

And determining the maximum regenerative braking torque which can be fed back by the battery according to the maximum charging power of the battery.

Optionally, the first braking module 203 is configured to:

Optionally, when the first motor braking demand torque is greater than the maximum braking torque, controlling the motor braking system to provide the maximum braking torque, and controlling the hydraulic braking system to provide the residual pressure, where the combined action of the maximum braking torque and the residual pressure can meet the first motor braking demand torque, including:

Fig. 8 is a block diagram illustrating yet another brake control apparatus according to an exemplary embodiment, and as shown in fig. 8, the apparatus 200 further includes:

the second obtaining module 206 is configured to determine, when the vehicle speed of the vehicle is less than the preset vehicle speed, a decreasing proportion of the braking torque provided by the motor braking system and an increasing proportion of the braking pressure provided by the hydraulic braking system according to the current vehicle speed, the braking torque currently provided by the motor braking system, the braking pressure currently provided by the hydraulic braking system, and the total braking torque required by the vehicle.

And the second braking module 207 is used for gradually reducing the braking torque provided by the motor braking system according to a decreasing proportion and gradually increasing the braking pressure provided by the hydraulic braking system according to an increasing proportion in the braking process, so that the combined action of the braking torque provided by the motor braking system and the braking pressure provided by the hydraulic braking system always meets the total braking torque in the braking process, and the braking torque provided by the motor braking system is zero when the vehicle speed of the vehicle is zero.

Alternatively, when the ABS is triggered,

With regard to the apparatus in the above-described embodiment, the specific manner in which each module performs the operation has been described in detail in the embodiment related to the method, and will not be elaborated here.

Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

It is to be understood that the present disclosure is not limited to the precise arrangements described above and shown in the drawings, and that various modifications and changes may be made therein without departing from the scope thereof, and that any combination between the various embodiments of the present disclosure may also be considered as disclosed herein, unless it departs from the spirit of the present disclosure. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A brake control method, characterized by being applied to a vehicle, the method comprising:

braking the vehicle according to the target braking mode;

the determining a target braking mode corresponding to the current motor working state in multiple preset braking modes comprises the following steps:

2. The method of claim 1,

the first braking mode is as follows: controlling a front shaft and a rear shaft of the vehicle to be in the electro-hydraulic composite braking mode according to a preset proportion;

3. The method of claim 1, further comprising:

4. The method of claim 3, wherein determining a maximum braking torque currently available based on the off-machine characteristic and the battery maximum charging power comprises:

5. The method of claim 3 or 4, wherein said controlling the torque provided by the motor braking system and the pressure provided by the hydraulic braking system based on the first motor braking demand torque and the maximum braking torque when braking using the electro-hydraulic compound braking mode comprises:

6. The method of claim 5, wherein said controlling the electric motor brake system to provide the maximum braking torque and controlling the hydraulic brake system to provide a surplus pressure when the first electric motor braking demand torque is greater than the maximum braking torque, the combined action of the maximum braking torque and the surplus pressure being capable of meeting the first electric motor braking demand torque, comprises:

7. The method of claim 1, further comprising:

8. The method of claim 2, wherein when the ABS is triggered,

the first braking mode is as follows: controlling a front shaft and a rear shaft of the vehicle to be in an electro-hydraulic composite ABS braking mode according to the preset proportion;

9. A brake control apparatus, characterized by being applied to a vehicle, the apparatus comprising:

the first braking module is used for braking the vehicle according to the target braking mode;

the judging module is used for:

10. The apparatus of claim 9,

11. The apparatus of claim 9, further comprising:

12. The apparatus of claim 11, wherein the processing module is configured to:

13. The apparatus of claim 11 or 12, wherein the first braking module is configured to:

14. The apparatus of claim 13, wherein said controlling the electric motor brake system to provide the maximum braking torque and controlling the hydraulic brake system to provide a surplus pressure when the first electric motor braking demand torque is greater than the maximum braking torque, the combined action of the maximum braking torque and the surplus pressure being capable of meeting the first electric motor braking demand torque comprises:

15. The apparatus of claim 9, further comprising:

16. The apparatus of claim 10, wherein when the ABS is triggered,