CN114801778A - Brake control method and device of electric automobile and electric automobile - Google Patents

Brake control method and device of electric automobile and electric automobile Download PDF

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Publication number
CN114801778A
CN114801778A CN202210246063.XA CN202210246063A CN114801778A CN 114801778 A CN114801778 A CN 114801778A CN 202210246063 A CN202210246063 A CN 202210246063A CN 114801778 A CN114801778 A CN 114801778A
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CN
China
Prior art keywords
auxiliary braking
auxiliary
vehicle
load
brake
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CN202210246063.XA
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Chinese (zh)
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傅洪
贾晔
李洋
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Beiqi Foton Motor Co Ltd
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Beiqi Foton Motor Co Ltd
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Priority to CN202210246063.XA priority Critical patent/CN114801778A/en
Publication of CN114801778A publication Critical patent/CN114801778A/en
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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
    • B60L15/2009—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed for braking
    • 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

Abstract

The application relates to the technical field of electric automobiles, in particular to a brake control method and device of an electric automobile and the electric automobile, wherein the method comprises the following steps: when the auxiliary braking intention of the driver is recognized, recognizing the current state of the electric automobile; judging whether the current state meets an auxiliary braking starting condition or not, and if so, controlling the electric automobile to enter a target auxiliary braking mode matched with an auxiliary braking intention; the method comprises the steps of detecting the actual load of the electric automobile, matching the corrected value of the target auxiliary braking mode according to the actual load, calculating the optimal auxiliary braking torque of the target auxiliary braking mode according to the corrected value, and controlling a driving motor to output the optimal auxiliary braking torque so as to assist the electric automobile in braking. Therefore, the problems that in the related art, the optimal auxiliary braking force cannot be generated only according to the auxiliary braking power matched with the gears, the accuracy and economy of braking control are poor, the driving experience is poor and the like are solved.

Description

Brake control method and device of electric automobile and electric automobile
Technical Field
The application relates to the technical field of electric automobiles, in particular to a brake control method and device of an electric automobile and the electric automobile.
Background
At present, an auxiliary braking device is usually assembled on a heavy electric automobile, and the auxiliary braking device is utilized for assisting braking so as to reduce the load of an automobile brake, ensure safe driving and prolong the service life of the brake.
In the related art, an electric vehicle usually matches auxiliary braking power according to a current gear, and performs auxiliary braking according to the matched auxiliary braking power. However, in the related art, the auxiliary braking power is matched only according to the gear, and the auxiliary braking power is not the optimal auxiliary braking force of the electric vehicle, so that the accuracy and economy of the braking control are poor, and the driving experience is reduced.
Content of application
The application provides a brake control method and device of an electric automobile and the electric automobile, and aims to solve the problems that in the related art, the optimal auxiliary braking force cannot be generated only according to auxiliary brake power matched with gears, the accuracy and economy of brake control are poor, the driving experience is poor, and the like.
An embodiment of a first aspect of the present application provides a brake control method for an electric vehicle, including the following steps: when the auxiliary braking intention of the driver is recognized, recognizing the current state of the electric automobile; judging whether the current state meets an auxiliary braking starting condition or not, and if so, controlling the electric automobile to enter a target auxiliary braking mode matched with the auxiliary braking intention; detecting the actual load of the electric automobile, matching the correction value of the target auxiliary braking mode according to the actual load, calculating the optimal auxiliary braking torque of the target auxiliary braking mode according to the correction value, and controlling a driving motor to output the optimal auxiliary braking torque so as to assist the braking of the electric automobile.
Further, when the target auxiliary braking mode is a multi-gear auxiliary braking mode, matching a correction value of the target auxiliary braking mode according to the actual load, and calculating an optimal auxiliary braking torque of the target auxiliary braking mode according to the correction value, includes: calculating a first auxiliary braking torque of the multi-gear auxiliary braking mode according to the actual gear of the multi-gear auxiliary braking mode and the actual speed of the electric automobile; matching a vehicle weight factor of the electric vehicle according to the load interval where the actual load is located, and correcting the first auxiliary braking torque by using the vehicle weight factor; and setting the smaller absolute value between the corrected first auxiliary braking torque and the maximum feedback torque of the driving motor as the optimal auxiliary braking torque.
Optionally, the load intervals include first to third load intervals, where a vehicle weight factor of the first load interval is greater than a vehicle weight factor of the second load interval, the vehicle weight factor of the second load interval is greater than a vehicle weight factor of the third load interval, a minimum value of the first load interval is greater than a maximum value of the second load interval, and a minimum value of the second load interval is greater than a maximum value of the third load interval.
Further, when the target auxiliary braking mode is the constant-speed auxiliary braking mode, calculating an optimal auxiliary braking torque of the target auxiliary braking mode according to a correction value that matches the target auxiliary braking mode according to the actual load, including: calculating a vehicle speed difference value between a target vehicle speed and an actual vehicle speed of the constant-speed auxiliary braking mode; matching an actual speed compensation value of the electric automobile according to the actual load; correcting the vehicle speed difference value by using the actual vehicle speed compensation value, and performing vehicle speed closed-loop calculation on the corrected vehicle speed difference value to obtain a second auxiliary braking torque; and setting the smaller of absolute values between the second auxiliary braking torque and the maximum feedback torque of the drive motor as the optimal auxiliary braking torque.
Optionally, the matching a vehicle speed compensation value of the electric vehicle according to the actual load includes: and matching an actual vehicle speed compensation value corresponding to the actual load by using a load and vehicle speed compensation value relation table, wherein the vehicle speed compensation value is reduced along with the increase of the load.
Further, identifying a driver's auxiliary braking intent includes: when a gear switch of an auxiliary brake switch is in an opening position corresponding to a multi-gear auxiliary brake mode, identifying that the auxiliary brake intention of the driver is a multi-gear auxiliary brake intention; and when a gear switch of the auxiliary brake switch is in an opening position corresponding to the constant-speed auxiliary brake mode, recognizing that the auxiliary brake intention of the driver is a constant-speed auxiliary brake intention.
Further, the current state includes an accelerator pedal opening state, a brake pedal opening state, a hand brake position state, a gear state of a transmission controller, a vehicle speed state of the electric vehicle and a state of an anti-lock system, and whether the current state meets an auxiliary brake opening condition is judged, including: and if the current opening degree of the accelerator pedal is smaller than a first opening degree, the current opening degree of the brake pedal is smaller than a second opening degree, the current position of the hand brake is in a non-pulling position, the current gear of the gearbox controller is in a preset gear, the actual speed of the electric automobile is greater than a preset speed, and the anti-lock system is in an inactivated state, the current state meets the auxiliary brake opening condition.
In a second aspect, an embodiment of the present application provides a brake control device for an electric vehicle, including: the identification module is used for identifying the current state of the electric automobile when the auxiliary braking intention of the driver is identified; the judging module is used for judging whether the current state meets an auxiliary braking starting condition or not, and if so, controlling the electric automobile to enter a target auxiliary braking mode matched with the auxiliary braking intention; and the braking module is used for detecting the actual load of the electric automobile, matching the corrected value of the target auxiliary braking mode according to the actual load, calculating the optimal auxiliary braking torque of the target auxiliary braking mode according to the corrected value, and controlling a driving motor to output the optimal auxiliary braking torque so as to assist the electric automobile in braking.
Further, when the target auxiliary braking mode is a multi-gear auxiliary braking mode, the braking module is specifically configured to: calculating a first auxiliary braking torque of the multi-gear auxiliary braking mode according to the actual gear of the multi-gear auxiliary braking mode and the actual speed of the electric automobile; matching a vehicle weight factor of the electric vehicle according to a load interval where the actual load is located, and correcting the first auxiliary braking torque by using the vehicle weight factor; and taking the smaller absolute value between the corrected first auxiliary braking torque and the maximum feedback torque of the driving motor as the optimal auxiliary braking torque.
Further, when the target auxiliary braking mode is the constant speed auxiliary braking mode, the braking module is specifically configured to: calculating a vehicle speed difference value between a target vehicle speed and an actual vehicle speed of the constant-speed auxiliary braking mode; matching an actual speed compensation value of the electric automobile according to the actual load; correcting the vehicle speed difference value by using the actual vehicle speed compensation value, and performing vehicle speed closed-loop calculation on the corrected vehicle speed difference value to obtain a second auxiliary braking torque; and setting the smaller of absolute values between the second auxiliary braking torque and the maximum feedback torque of the drive motor as the optimal auxiliary braking torque.
In an embodiment of a third aspect of the present application, an electric vehicle is provided, which includes the brake control device of the electric vehicle described in the foregoing embodiment.
Therefore, the application has at least the following beneficial effects:
the auxiliary braking power of the electric automobile is adjusted according to the actual load, the optimal auxiliary braking force is generated, the accuracy and economy of braking control are effectively improved, the influence of load change on the braking effect is reduced or even avoided, the stability of the automobile during braking is effectively improved, and the driving experience is improved. Therefore, the technical problems that in the related art, the optimal auxiliary braking force cannot be generated only according to the auxiliary braking power matched with the gears, the accuracy and economy of braking control are poor, the driving experience is poor and the like are solved.
Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.
Drawings
The foregoing and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic structural diagram of a brake control system of an electric vehicle according to an embodiment of the present application;
FIG. 2 is a schematic flow chart illustrating a braking control method for an electric vehicle according to an embodiment of the present application;
FIG. 3 is a schematic flow chart illustrating a braking control method for an electric vehicle according to an embodiment of the present application;
fig. 4 is a block diagram schematically illustrating a brake control apparatus of an electric vehicle according to an embodiment of the present application.
Detailed Description
Reference will now be made in detail to embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present application and should not be construed as limiting the present application.
At present, heavy-duty vehicles are often equipped with auxiliary braking devices to reduce the load of service brakes, ensure safe driving and reduce energy consumption. The heavy pure electric vehicle utilizes the characteristics of a driving motor and a power battery, the auxiliary braking is realized in an energy recovery mode, and the auxiliary braking force is different according to the setting of the auxiliary braking gear. However, in the related art, the auxiliary braking force is only output according to the gear, and the requirement that the driver needs to drive at a stable speed under some working conditions, such as long downhill slope, cannot be met; in addition, the load of the heavy vehicle varies a lot, and if the magnitude of the auxiliary braking force is adjusted only according to the gear, a significant difference in driving feeling may be caused when the load varies a lot.
The method is based on the problems that the requirements of multi-gear auxiliary braking and constant-speed braking are not considered simultaneously in the related technology, and the auxiliary braking force is not adjusted according to the change of the vehicle load, so that the stability and the economical efficiency of the vehicle are poor, and the like. To this end, the embodiments of the present application propose a solution to adjust the auxiliary power according to the change of the vehicle load, taking into account the requests of the multi-gear auxiliary brake and the constant speed brake at the same time.
The following will describe a brake control method and device for an electric vehicle and a vehicle according to an embodiment of the present application with reference to the drawings. Aiming at the problems that in the related technology mentioned in the background technology center, the optimal auxiliary braking force cannot be generated only according to the auxiliary braking power matched with the gear, the accuracy and economy of braking control are poor, and the driving experience is poor, the application provides the braking control method of the electric automobile. Therefore, the technical problems that in the related art, the optimal auxiliary braking force cannot be generated only according to the auxiliary braking power matched with the gears, the accuracy and economy of braking control are poor, the driving experience is poor and the like are solved.
Specifically, fig. 1 is a schematic structural diagram of a brake control system of an electric vehicle in an embodiment of the present application.
As shown in fig. 1, the system includes: the system comprises a vehicle control unit 1, an auxiliary brake switch 2, an accelerator pedal 3, a brake pedal 4, a hand brake 5, a gradient sensor 6, a gearbox controller 7, a brake anti-lock controller 8, a power battery management system 9 and a driving motor controller 10.
The vehicle controller 1 is used for receiving a gear switch signal of the auxiliary brake switch 2, a pedal opening degree signal of the accelerator pedal 3, a pedal switch signal of the brake pedal 4, a position signal of the hand brake 5 which is put down/pulled up, a gradient signal of the gradient sensor 6, a gear signal of the gearbox controller 7, a vehicle speed signal of the anti-lock brake controller 8, an anti-lock control activation signal and the like, judging whether the vehicle can enter an auxiliary brake driving mode, and distinguishing whether the vehicle enters multi-gear auxiliary brake or constant-speed brake; meanwhile, the maximum torque which CAN be fed back by the whole vehicle is calculated according to the maximum feedback power signal of the power battery management system 9, the maximum feedback torque of the driving motor controller 10 and the rotating speed signal, and the calculated target torque is sent to the CAN bus. The driving motor controller 10 receives information such as a target torque on the CAN bus, and controls the torque of the driving motor to change accordingly.
Specifically, each part of the brake control system of the electric automobile functions as follows:
the vehicle control unit 1: receiving an auxiliary brake switch signal, an accelerator pedal opening signal, a brake pedal switch signal, a hand brake position signal, a gradient signal of a gradient sensor, a gear signal of a gearbox controller, a vehicle speed signal and an anti-lock control activation signal of an anti-lock brake controller, a maximum feedback power signal of a power battery system, a motor rotating speed and a maximum feedback torque signal of a driving motor controller, judging an auxiliary brake related request of a driver, realizing auxiliary brake multi-gear torque control or constant speed control, outputting corresponding auxiliary brake torque, carrying out torque coordination processing, and sending the processed target torque to a CAN bus.
Auxiliary brake switch 2: the intention of the driver for assisting braking is reflected through the adjustment of the switch, and a switch signal is fed back to the vehicle control unit.
Accelerator pedal 3: the intention of a driver for driving is reflected by the change of the opening degree of the accelerator pedal, and a pedal opening degree signal is fed back to the vehicle control unit.
The brake pedal 4: the demand of a driver for braking the vehicle is reflected through the switch state of the brake pedal, and a brake switch signal is fed back to the vehicle control unit.
And (5) a hand brake: the position signal of the hand brake reflects the requirement of a driver for braking the vehicle and feeds back the position signal of the hand brake to the whole vehicle controller.
The gradient sensor 6: and detecting the gradient information of the road surface, and feeding back a gradient signal to the vehicle control unit.
The transmission controller 7: and controlling automatic gear switching and sending a gear signal to the CAN bus.
Brake anti-lock controller 8: and detecting wheel speed information of the vehicle, performing anti-lock brake control on the vehicle, and sending the calculated vehicle speed signal and the brake anti-lock control activation signal to the CAN bus.
Power battery management system 9: and calculating the maximum feedback power according to the information such as the charge state, the temperature and the like of the power battery, and sending the calculated result to the CAN bus.
Drive motor controller 10: and receiving information such as target torque on the CAN bus, controlling actions such as torque change of the driving motor, calculating the maximum feedback torque, and sending the actual rotating speed and the maximum feedback torque of the driving motor to the CAN bus.
Fig. 2 is a schematic flow chart of a braking control method of an electric vehicle according to an embodiment of the present application.
As shown in fig. 2, the brake control method of the electric vehicle includes the steps of:
in step S101, when the driver' S intention to assist braking is recognized, the current state of the electric vehicle is recognized.
Wherein the auxiliary braking intent may comprise a multi-gear auxiliary braking intent and a constant speed auxiliary braking intent; the current state may include an accelerator pedal opening state, a brake pedal opening state, a position state of a hand brake, a gear state of a transmission controller, a vehicle speed state of the electric vehicle, a state of an anti-lock braking system, and/or the like.
In the present embodiment, recognizing the driver's intention to assist braking includes: when a gear switch of the auxiliary brake switch is in an opening position corresponding to a multi-gear auxiliary brake mode, recognizing that an auxiliary brake intention of a driver is a multi-gear auxiliary brake intention; and when the gear switch of the auxiliary brake switch is in an opening position corresponding to the constant-speed auxiliary brake mode, recognizing that the auxiliary brake intention of the driver is the constant-speed auxiliary brake intention.
The starting position corresponding to the multi-gear auxiliary braking mode can comprise a plurality of positions such as a gear I position and a gear II position.
It can be understood that the vehicle control unit can determine the original specific auxiliary braking intention of the driver according to the operation state of the auxiliary braking switch, so as to be used for subsequent auxiliary braking control.
In step S102, it is determined whether the current state satisfies an auxiliary brake on condition, and if so, the electric vehicle is controlled to enter a target auxiliary brake mode matching the auxiliary brake intention.
The target auxiliary braking mode can include a multi-gear auxiliary braking mode and a constant-speed auxiliary braking mode, and the target auxiliary braking mode can be determined by an auxiliary braking intention, for example, when the auxiliary braking intention is the multi-gear auxiliary braking intention, the electric vehicle can be controlled to enter the multi-gear auxiliary braking mode when an auxiliary braking opening condition is met; when the auxiliary braking intention is the constant-speed auxiliary braking intention, the electric automobile can be controlled to enter the constant-speed auxiliary braking mode when the auxiliary braking opening condition is met.
It can be understood that the vehicle control unit may determine whether an auxiliary brake opening condition is satisfied according to the accelerator pedal opening degree signal, the brake pedal switch signal, the hand brake position signal, the transmission controller gear signal, the vehicle speed signal of the anti-lock brake controller, and the anti-lock activation signal, output a target torque for regular driving if not, and control the electric vehicle to enter a target auxiliary brake mode determined according to the auxiliary brake intention if satisfied.
In this embodiment, if the current opening degree of the accelerator pedal is smaller than the first opening degree, the current opening degree of the brake pedal is smaller than the second opening degree, the current position of the hand brake is in the non-pulling-up position, the current gear of the transmission controller is in the preset gear, the actual speed of the electric vehicle is greater than the preset speed, and the anti-lock system is in the inactive state and simultaneously satisfied, it is determined that the current state satisfies the auxiliary brake-on condition.
The first opening degree and the second opening degree can be specifically set according to actual conditions, and are not specifically limited, and when the current opening degree of the accelerator pedal is smaller than the first opening degree, the accelerator pedal is not triggered; and when the current opening degree of the brake pedal is smaller than the second opening degree, the brake pedal is not triggered.
The preset gear can be a forward gear (a D gear).
The preset vehicle speed can be specifically calibrated, for example, 8km/h or 10km/h can be set.
It can be understood that when the vehicle control unit detects that conditions such as an accelerator pedal is not triggered, a brake pedal is not triggered, a gearbox is in a D gear, an actual vehicle speed is greater than a certain value, and an anti-lock system is not activated are simultaneously met, it can be determined that a current state of the electric vehicle meets an auxiliary brake starting condition, and the electric vehicle can be controlled to enter an auxiliary brake mode.
In step S103, an actual load of the electric vehicle is detected, a correction value for the target auxiliary braking mode is matched according to the actual load, an optimal auxiliary braking torque for the target auxiliary braking mode is calculated according to the correction value, and the driving motor is controlled to output the optimal auxiliary braking torque to assist braking of the electric vehicle.
It can be understood that, in the embodiment of the application, when the auxiliary braking of the electric automobile is controlled, the change of the load of the automobile can be considered, and the auxiliary braking force of the automobile is correspondingly adjusted, so that the driving feeling difference caused by the change of the load is reduced, and the driving experience is improved.
In this embodiment, when the target auxiliary braking mode is the multi-range auxiliary braking mode, calculating the optimal auxiliary braking torque of the target auxiliary braking mode according to the correction value based on the correction value matching the target auxiliary braking mode according to the actual load includes: calculating a first auxiliary braking torque of the multi-gear auxiliary braking mode according to the actual gear of the multi-gear auxiliary braking mode and the actual speed of the electric automobile; matching a vehicle weight factor of the electric vehicle according to a load interval where the actual load is located, and correcting the first auxiliary braking torque by using the vehicle weight factor; and taking the smaller absolute value between the corrected first auxiliary braking torque and the maximum feedback torque of the driving motor as the optimal auxiliary braking torque.
The load interval comprises a first load interval, a second load interval and a third load interval, wherein the vehicle weight factor of the first load interval is larger than that of the second load interval, the vehicle weight factor of the second load interval is larger than that of the third load interval, the minimum value of the first load interval is larger than the maximum value of the second load interval, and the minimum value of the second load interval is larger than the maximum value of the third load interval.
It should be noted that the load interval may be specifically set according to the load of the electric vehicle, and is not specifically limited, for example, the load of the electric vehicle may be divided into three levels, i.e., full load, half load, and no load, so that the first load interval may correspond to a full load level, the second load interval may correspond to a half load level, and the third load interval may correspond to an empty level.
The vehicle weight factors corresponding to different load intervals can be specifically calibrated or specifically set, when the vehicle weight factors are specifically applied, the value range of the vehicle weight factors can be 0-1, the vehicle weight factors are increased along with the increase of the load, and the auxiliary braking force can be increased when the load is increased so as to reduce the driving feeling difference caused by the change of the load, for example, the full-load vehicle weight factor can be set to be 1 or 0.9 and the like, the half-load vehicle weight factor can be set to be 0.5 or 0.6 and the like, and the no-load vehicle weight factor can be set to be 0.1 or 0.2 and the like.
Specifically, after the vehicle control unit controls the electric vehicle to enter the multi-gear auxiliary braking control, first, a first auxiliary braking torque is calculated according to a multi-gear auxiliary braking control gear signal and a vehicle speed signal sent by the anti-lock braking controller; then considering the influence of different vehicle weights on the auxiliary braking torque, matching corresponding vehicle weight factors according to the actual load, and calculating the product of the vehicle weight factors and the first auxiliary braking torque; and finally, comparing the product of the vehicle weight factor and the first auxiliary braking torque with the maximum feedback torque of the driving motor, and outputting the smaller absolute value of the two compared values.
In this embodiment, calculating the first auxiliary braking torque of the multi-gear auxiliary braking mode according to the actual gear of the multi-gear auxiliary braking mode and the actual vehicle speed of the electric vehicle includes: and searching a gear-vehicle speed-auxiliary braking torque relation table of the multi-gear auxiliary braking mode to determine the first auxiliary braking torque.
It can be understood that the embodiment of the application can preset the gear-vehicle speed-auxiliary braking torque relation, and then quickly determine the auxiliary braking torque according to the actual gear and the actual vehicle speed. The actual gears can include a gear I, a gear II and the like, are specifically determined according to the position of the auxiliary brake switch, and the larger the gear is, the larger the corresponding auxiliary brake torque is.
In some embodiments, the vehicle controller may calculate the maximum feedback torque available for the entire vehicle according to the maximum feedback power sent by the power battery management system and the maximum feedback torque of the motor sent by the driving motor controller, and by combining the actual rotation speed of the driving motor.
In this embodiment, when the target auxiliary braking mode is the constant-speed auxiliary braking mode, calculating the optimum auxiliary braking torque of the target auxiliary braking mode according to a correction value according to which the actual load matches the target auxiliary braking mode, includes: calculating a vehicle speed difference value between a target vehicle speed and an actual vehicle speed of the constant-speed auxiliary braking mode; matching an actual speed compensation value of the electric automobile according to the actual load; correcting the vehicle speed difference value by using the actual vehicle speed compensation value, and performing vehicle speed closed-loop calculation on the corrected vehicle speed difference value to obtain a second auxiliary braking torque; the smaller of the absolute values of the second assist braking torque and the maximum feedback torque of the drive motor is taken as the optimum assist braking torque.
In the embodiment of the present application, the auxiliary braking torque may be calculated by using a vehicle speed closed-loop algorithm, which may be selected according to actual conditions, and is not particularly limited.
Specifically, when the vehicle control unit performs constant-speed auxiliary braking control, firstly, calculating a difference value according to a target vehicle speed signal confirmed when a constant-speed gear is pressed down and an actual vehicle speed fed back by the anti-lock braking controller, calculating a vehicle speed compensation value according to different vehicle weights, and comprehensively obtaining a final vehicle speed difference value; and then calculating the auxiliary braking torque through a vehicle speed closed loop, finally comparing the auxiliary braking torque with the maximum feedback torque, and outputting a smaller absolute value after the comparison of the auxiliary braking torque and the maximum feedback torque.
It should be noted that, if the absolute value of the calculated auxiliary braking torque is smaller than the maximum feedback torque, that is, there is a possibility that the current target vehicle speed cannot be maintained, the driver may be prompted to adjust the target vehicle speed or to depress the brake pedal by means of an instrument or the like.
In this embodiment, matching the vehicle speed compensation value of the electric vehicle according to the actual load includes: and matching an actual vehicle speed compensation value corresponding to the actual load by using the relation table of the load and the vehicle speed compensation value.
The relationship table of the load and the vehicle speed compensation value may be specifically calibrated or specifically set, which is not specifically limited, and the vehicle speed compensation value decreases with the increase of the load, and the auxiliary braking force may be increased when the load increases, so as to reduce the driving feeling difference caused by the load change.
In some embodiments, the vehicle control unit may coordinate the optimal auxiliary braking torque with the output torque in the normal driving mode and send the optimal auxiliary braking torque to the drive motor controller through the CAN bus.
According to the brake control method of the electric automobile, the classified auxiliary brake and the auxiliary brake with the constant speed can be realized, the auxiliary brake power of the electric automobile is adjusted according to the actual load, the optimal auxiliary brake force is generated, the accuracy and the economy of brake control are effectively improved, the influence of load change on the brake effect is reduced or even avoided, the stability of the automobile during brake is effectively improved, and the driving experience is improved.
The following will explain a braking control method of an electric vehicle by a specific embodiment, as shown in fig. 3, including the following steps:
in step 201, the vehicle control unit determines whether the driver has an auxiliary brake on request according to the operation state of the auxiliary brake switch, and if so, executes step 202.
In step 202, the vehicle controller calculates the maximum feedback torque Tq available for the entire vehicle according to the maximum feedback power sent by the power battery management system and the maximum feedback torque of the motor sent by the driving motor controller, and then according to the actual rotating speed of the driving motor gmax 。
In step 203, the vehicle control unit judges whether an auxiliary brake opening condition is met according to the accelerator pedal opening degree signal, the brake pedal switch signal, the hand brake position signal, the gear signal of the gearbox controller, the vehicle speed signal of the anti-lock brake controller and the anti-lock activation signal; if yes, go to step 204, otherwise go to step 213.
In step 204, the vehicle control unit determines to enter an auxiliary braking driving mode.
In step 205, the vehicle control unit determines whether the signal sent by the auxiliary brake switch is a multi-gear request such as I gear, II gear, etc., if so, step 206 is executed, otherwise, step 209 is executed.
In step 206, the vehicle control unit calculates an auxiliary braking torque Tq according to different gear signals and vehicle speed signals of the auxiliary braking switch 1 Wherein the larger the gear, the larger the corresponding auxiliary braking torque.
In step 207, since different vehicle weights have different influences on the auxiliary braking torque, after the vehicle controller calculates the vehicle weight, the vehicle weight obtained by calculation may be divided into three levels, i.e., full load, half load, and no load, and a corresponding vehicle weight factor may be calculated to obtain the auxiliary braking torque Tq calculated in step 206 1 Correcting to obtain final torque Tq under different auxiliary braking gears 2 (ii) a Wherein, as the vehicle weight increases, the auxiliary braking torque increases accordingly.
In step 208, the absolute value of the auxiliary braking torque obtained in step 207 and the absolute value of the maximum feedback torque obtained in step 202 are compared, and the smaller absolute value of the two compared is output.
In step 209, the vehicle control unit determines whether the auxiliary brake switch is a constant speed gear request, and determines whether a constant speed control condition is satisfied according to the gradient signal, if so, step 210 is executed, otherwise, step 213 is executed.
In step 210, the vehicle control unit confirms the target vehicle speed signal V according to the constant speed gear pressing t And actual vehicle speed V fed back by the anti-lock brake controller a Calculating the difference value of the signals, and simultaneously calculating the vehicle speed compensation value V according to different vehicle weights m 。
In step 211, the vehicle control unit calculates a vehicle speed difference Δ V ═ V t -V a -V m Calculating the auxiliary braking torque through a vehicle speed closed loop to obtain the torque Tq 3 。
In step 212, the absolute value of the auxiliary braking torque obtained in step 211 and the absolute value of the maximum feedback torque obtained in step 202 are compared, and the smaller absolute value of the two compared is output; meanwhile, if Tq is outputted gmax It indicates that the calculated brake assist torque exceeds the current vehicle energy recovery capability and that the target vehicle speed V cannot be maintained t The possibility of driving needs to remind the driver to adjust the target speed or press the brake pedal by means of instruments and the like.
In step 213, the hybrid controller outputs a target torque for regular driving when the auxiliary brake is not activated.
In step 214, the vehicle control unit coordinates the target torque output in steps 208, 212 and 213, and transmits the result to the driving motor controller via the CAN bus, and the driving motor controller controls the torque output of the driving motor according to the target torque.
In conclusion, the embodiment of the application can realize the functions of graded auxiliary braking and constant-speed auxiliary braking by identifying the intention of the driver and the vehicle state and adopting an energy recovery mode under the condition of not changing the configuration of the power system of the electric vehicle when the driver has the auxiliary braking requirement; meanwhile, the influence of the vehicle weight load is considered, the power output by the auxiliary brake is correspondingly adjusted, so that the driving feeling difference caused by the load change is reduced, the requirements of vehicle deceleration and stability can be met, the energy consumption can be effectively reduced, the triggering times of a brake pedal are reduced, the abrasion is reduced, and the economy of the whole vehicle is improved.
Next, a brake control apparatus for an electric vehicle according to an embodiment of the present application will be described with reference to the drawings.
Fig. 4 is a block diagram schematically illustrating a brake control device of an electric vehicle according to an embodiment of the present invention.
As shown in fig. 4, the brake control device 100 for an electric vehicle includes: an identification module 110, a determination module 120, and a braking module 130.
The identification module 110 is used for identifying the current state of the electric automobile when the auxiliary braking intention of the driver is identified; the judging module 120 is configured to judge whether the current state meets an auxiliary braking starting condition, and if so, control the electric vehicle to enter a target auxiliary braking mode matched with an auxiliary braking intention; the braking module 130 is configured to detect an actual load of the electric vehicle, match a correction value of the target auxiliary braking mode according to the actual load, calculate an optimal auxiliary braking torque of the target auxiliary braking mode according to the correction value, and control the driving motor to output the optimal auxiliary braking torque to assist braking of the electric vehicle.
Further, when the target auxiliary braking mode is the multi-gear auxiliary braking mode, the braking module 130 is specifically configured to: calculating a first auxiliary braking torque of the multi-gear auxiliary braking mode according to the actual gear of the multi-gear auxiliary braking mode and the actual speed of the electric automobile; matching a vehicle weight factor of the electric vehicle according to a load interval where the actual load is located, and correcting the first auxiliary braking torque by using the vehicle weight factor; and taking the smaller absolute value between the corrected first auxiliary braking torque and the maximum feedback torque of the driving motor as the optimal auxiliary braking torque.
Further, when the target auxiliary braking mode is the constant-speed auxiliary braking mode, the braking module 130 is specifically configured to: calculating a vehicle speed difference value between a target vehicle speed and an actual vehicle speed of the constant-speed auxiliary braking mode; matching an actual speed compensation value of the electric automobile according to the actual load; correcting the vehicle speed difference value by using the actual vehicle speed compensation value, and performing vehicle speed closed-loop calculation on the corrected vehicle speed difference value to obtain a second auxiliary braking torque; the smaller of the absolute values of the second auxiliary braking torque and the maximum feedback torque of the drive motor is set as the optimum auxiliary braking torque.
It should be noted that the foregoing explanation of the embodiment of the braking control method for an electric vehicle is also applicable to the braking control device for an electric vehicle of this embodiment, and will not be repeated herein.
According to the brake control device of the electric automobile, the auxiliary brake of hierarchical auxiliary brake and constant speed of a motor vehicle can be realized, the auxiliary brake power of the electric automobile is adjusted according to actual load, the optimal auxiliary brake force is generated, the accuracy and the economical efficiency of brake control are effectively improved, the influence of load change on the brake effect is reduced or even avoided, the stability of the automobile during brake is effectively improved, and the driving experience is improved.
The embodiment also provides an electric automobile which comprises the brake control device of the electric automobile. The automobile can meet the requirements of vehicle deceleration and stability, reduce energy consumption and improve the economy of the whole automobile.
In the description herein, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or N embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "N" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more N executable instructions for implementing steps of a custom logic function or process, and alternate implementations are included within the scope of the preferred embodiment of the present application in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of implementing the embodiments of the present application.
It should be understood that portions of the present application may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. If implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.

Claims (10)

1. A brake control method of an electric vehicle is characterized by comprising the following steps:
when the auxiliary braking intention of the driver is recognized, recognizing the current state of the electric automobile;
judging whether the current state meets an auxiliary braking starting condition or not, and if so, controlling the electric automobile to enter a target auxiliary braking mode matched with the auxiliary braking intention; and
detecting the actual load of the electric automobile, matching the correction value of the target auxiliary braking mode according to the actual load, calculating the optimal auxiliary braking torque of the target auxiliary braking mode according to the correction value, and controlling a driving motor to output the optimal auxiliary braking torque so as to assist the braking of the electric automobile.
2. The method according to claim 1, wherein when the target auxiliary braking mode is a multi-range auxiliary braking mode, calculating an optimal auxiliary braking torque of the target auxiliary braking mode based on a correction value according to which the actual load matches the target auxiliary braking mode, comprises:
calculating a first auxiliary braking torque of the multi-gear auxiliary braking mode according to the actual gear of the multi-gear auxiliary braking mode and the actual speed of the electric automobile;
matching a vehicle weight factor of the electric vehicle according to a load interval where the actual load is located, and correcting the first auxiliary braking torque by using the vehicle weight factor;
and taking the smaller absolute value between the corrected first auxiliary braking torque and the maximum feedback torque of the driving motor as the optimal auxiliary braking torque.
3. The method according to claim 2, wherein the load intervals include first to third load intervals, wherein a vehicle weight factor of the first load interval is greater than a vehicle weight factor of the second load interval, the vehicle weight factor of the second load interval is greater than a vehicle weight factor of the third load interval, a minimum value of the first load interval is greater than a maximum value of the second load interval, and a minimum value of the second load interval is greater than a maximum value of the third load interval.
4. The method according to claim 1, wherein when the target auxiliary braking mode is a constant-speed auxiliary braking mode, calculating an optimal auxiliary braking torque of the target auxiliary braking mode according to a correction value according to which the actual load matches the target auxiliary braking mode, includes:
calculating a vehicle speed difference value between a target vehicle speed and an actual vehicle speed of the constant-speed auxiliary braking mode;
matching an actual speed compensation value of the electric automobile according to the actual load;
correcting the vehicle speed difference value by using the actual vehicle speed compensation value, and performing vehicle speed closed-loop calculation on the corrected vehicle speed difference value to obtain a second auxiliary braking torque;
and setting the smaller of absolute values between the second auxiliary braking torque and the maximum feedback torque of the drive motor as the optimal auxiliary braking torque.
5. The method of claim 4, wherein said matching a vehicle speed compensation value of the electric vehicle based on the actual load comprises:
and matching an actual vehicle speed compensation value corresponding to the actual load by using a load and vehicle speed compensation value relation table, wherein the vehicle speed compensation value is reduced along with the increase of the load.
6. The method of claim 1, wherein identifying a driver's auxiliary braking intent comprises:
when a gear switch of an auxiliary brake switch is in an opening position corresponding to a multi-gear auxiliary brake mode, identifying that the auxiliary brake intention of the driver is a multi-gear auxiliary brake intention;
and when a gear switch of the auxiliary brake switch is in an opening position corresponding to the constant-speed auxiliary brake mode, recognizing that the auxiliary brake intention of the driver is a constant-speed auxiliary brake intention.
7. The method of claim 1, wherein the current state comprises an accelerator pedal opening state, a brake pedal opening state, a hand brake position state, a transmission controller gear state, an electric vehicle speed state and an anti-lock braking system state, and the determining whether the current state meets an auxiliary brake on condition comprises:
if the current opening degree of the accelerator pedal is smaller than a first opening degree, the current opening degree of the brake pedal is smaller than a second opening degree, the current position of the hand brake is in a non-pulling position, the current gear of the gearbox controller is in a preset gear, the actual speed of the electric automobile is larger than a preset speed, and the anti-lock system is in an inactivated state and simultaneously meets the condition, the current state meets the auxiliary brake opening condition.
8. A brake control device for an electric vehicle, comprising:
the identification module is used for identifying the current state of the electric automobile when the auxiliary braking intention of the driver is identified;
the judging module is used for judging whether the current state meets an auxiliary braking starting condition or not, and if so, controlling the electric automobile to enter a target auxiliary braking mode matched with the auxiliary braking intention; and
and the braking module is used for detecting the actual load of the electric automobile, matching the corrected value of the target auxiliary braking mode according to the actual load, calculating the optimal auxiliary braking torque of the target auxiliary braking mode according to the corrected value, and controlling a driving motor to output the optimal auxiliary braking torque so as to assist the electric automobile in braking.
9. The apparatus of claim 7, wherein when the target auxiliary braking mode is a multi-range auxiliary braking mode, the braking module is specifically configured to:
calculating a first auxiliary braking torque of the multi-gear auxiliary braking mode according to the actual gear of the multi-gear auxiliary braking mode and the actual speed of the electric automobile;
matching a vehicle weight factor of the electric vehicle according to a load interval where the actual load is located, and correcting the first auxiliary braking torque by using the vehicle weight factor;
taking the smaller absolute value between the corrected first auxiliary braking torque and the maximum feedback torque of the driving motor as the optimal auxiliary braking torque;
when the target auxiliary braking mode is the constant-speed auxiliary braking mode, the braking module is specifically configured to:
calculating a vehicle speed difference value between a target vehicle speed and an actual vehicle speed of the constant-speed auxiliary braking mode;
matching an actual speed compensation value of the electric automobile according to the actual load;
correcting the vehicle speed difference value by using the actual vehicle speed compensation value, and performing vehicle speed closed-loop calculation on the corrected vehicle speed difference value to obtain a second auxiliary braking torque;
and setting the smaller absolute value between the second auxiliary braking torque and the maximum feedback torque of the driving motor as the optimal auxiliary braking torque.
10. An electric vehicle characterized by comprising the brake control apparatus for an electric vehicle according to any one of claims 8 to 9.
CN202210246063.XA 2022-03-14 2022-03-14 Brake control method and device of electric automobile and electric automobile Pending CN114801778A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210246063.XA CN114801778A (en) 2022-03-14 2022-03-14 Brake control method and device of electric automobile and electric automobile

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210246063.XA CN114801778A (en) 2022-03-14 2022-03-14 Brake control method and device of electric automobile and electric automobile

Publications (1)

Publication Number Publication Date
CN114801778A true CN114801778A (en) 2022-07-29

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210246063.XA Pending CN114801778A (en) 2022-03-14 2022-03-14 Brake control method and device of electric automobile and electric automobile

Country Status (1)

Country Link
CN (1) CN114801778A (en)

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