CN112874317A - Braking method and device of electric vehicle and electric vehicle - Google Patents
Braking method and device of electric vehicle and electric vehicle Download PDFInfo
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- CN112874317A CN112874317A CN202110112112.6A CN202110112112A CN112874317A CN 112874317 A CN112874317 A CN 112874317A CN 202110112112 A CN202110112112 A CN 202110112112A CN 112874317 A CN112874317 A CN 112874317A
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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
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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
- B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
- B60L3/12—Recording operating variables ; Monitoring of operating variables
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/72—Electric energy management in electromobility
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Abstract
The application discloses a braking method and a braking device of an electric vehicle and the electric vehicle, wherein the method comprises the following steps: collecting the current opening degree of a brake pedal of the electric vehicle; calculating a target deceleration of the electric vehicle according to the current opening degree, and determining a hydraulic braking force and an electric braking force of a braking system according to the target deceleration; while braking based on the hydraulic braking force, an adjustment value of the electric braking force is generated in accordance with the detected actual deceleration of the electric vehicle so that the actual deceleration is the same as the target deceleration. Therefore, the problems that the actual braking effect is different under the same opening degree and the same braking intention at present, the braking safety is reduced, the braking experience of a driver is reduced and the like are solved.
Description
Technical Field
The application relates to the technical field of new energy automobiles, in particular to a braking method and a braking device for an electric vehicle and the electric vehicle.
Background
The braking force of the current electric vehicle comprises hydraulic braking force and electric braking force, and the corresponding hydraulic braking force and electric braking force under the same opening degree of a brake pedal are the same, namely the total braking force is the same, so that the braking stroke and the total braking force are in one-to-one correspondence relationship.
However, when the vehicle is under different loads and different gradient road surfaces, the actual braking deceleration of the vehicle is different under the same opening degree and braking intention of the driver, and the braking feeling is also inconsistent, so that the braking safety and the braking experience of the driver are greatly reduced.
Content of application
The application provides a braking method and a braking device of an electric vehicle and the electric vehicle, which aim to solve the problems that the actual braking effect is different under the same opening degree and the same braking intention at present, the braking safety is reduced, the braking experience of a driver is reduced, and the like.
An embodiment of the first aspect of the present application provides a braking method for an electric vehicle, including the following steps: collecting the current opening degree of a brake pedal of the electric vehicle; calculating a target deceleration of the electric vehicle according to the current opening degree, and determining a hydraulic braking force and an electric braking force of the braking system according to the target deceleration; while braking based on the hydraulic braking force, an adjustment value of the electric braking force is generated in accordance with the detected actual deceleration of the electric vehicle so that the actual deceleration is the same as the target deceleration.
Further, the generating of the adjustment value of the electric braking force according to the detected actual deceleration of the electric vehicle includes: calculating a difference between the actual deceleration and the target deceleration; determining the adjusting time of the difference value according to a preset brake preference; and calculating to obtain the adjusting value according to the difference and the adjusting time.
Further, the calculating a target deceleration of the electric vehicle according to the current opening degree includes: generating a relation table of the opening degree and the deceleration according to preset brake preference; and searching the relation table of the opening degree and the deceleration according to the current opening degree to obtain the target deceleration.
Further, detecting an actual deceleration of the electric vehicle includes: collecting pulse signals of a wheel speed sensor, and counting the number of the pulse signals in a first preset time; calculating the wheel speed of the wheels according to the number of the pulse signals, and calculating the average wheel speed of all the wheels; when the difference value between the wheel speed and the average wheel speed is larger than a first threshold value and the ratio of the difference value to the average wheel speed is larger than a second threshold value, judging that the wheel speed is not credible, and taking the average value of the residual wheel speeds as the actual vehicle speed; and calculating to obtain deceleration according to two adjacent actual vehicle speeds, and taking the average value of all decelerations in a second preset time as the actual deceleration.
Further, still include: collecting the detection number of the brake stroke sensor voltage and the wheel speed sensor pulse signals; determining that the brake stroke sensor is faulty when the voltage is greater than or less than a rated voltage; when the difference value between the detected number and the calibrated number corresponding to the wheel speed is greater than a preset value, judging that the wheel speed sensor has a fault; and if the brake stroke sensor and/or the wheel speed sensor have faults, braking according to preset electric braking force and the hydraulic braking force, and performing fault reminding.
An embodiment of a second aspect of the present application provides a braking device for an electric vehicle, including: the acquisition module is used for acquiring the current opening degree of a brake pedal of the electric vehicle; the determining module is used for calculating a target deceleration of the electric vehicle according to the current opening degree and determining a hydraulic braking force and an electric braking force of the braking system according to the target deceleration; the first braking module is used for generating an adjusting value of the electric braking force according to the detected actual deceleration of the electric vehicle while braking based on the hydraulic braking force, so that the actual deceleration is the same as the target deceleration.
Further, the first brake module includes: a first calculation unit that calculates a difference between the actual deceleration and the target deceleration; the determining unit is used for determining the adjusting time of the difference value according to preset brake preference; and the second calculating unit is used for calculating the adjusting value according to the difference value and the adjusting time.
Further, the determining module includes: the generating unit is used for generating an opening degree and deceleration relation table according to preset brake preference; and the table look-up unit is used for looking up the relation table of the opening degree and the deceleration according to the current opening degree to obtain the target deceleration.
Further, still include: a detection module for detecting an actual deceleration of the electric vehicle, comprising: collecting pulse signals of a wheel speed sensor, and counting the number of the pulse signals in a first preset time; calculating the wheel speed of the wheels according to the number of the pulse signals, and calculating the average wheel speed of all the wheels; when the difference value between the wheel speed and the average wheel speed is larger than a first threshold value and the ratio of the difference value to the average wheel speed is larger than a second threshold value, judging that the wheel speed is not credible, and taking the average value of the residual wheel speeds as the actual vehicle speed; calculating according to two adjacent actual speeds to obtain deceleration, and taking the average value of all decelerations in a second preset time as the actual deceleration; the fault determination module is used for acquiring the voltage of a brake travel sensor and the detection number of pulse signals of a wheel speed sensor, determining the fault of the brake travel sensor when the voltage is greater than or less than the rated voltage, and determining the fault of the wheel speed sensor when the difference value between the detection number and the calibration number corresponding to the wheel speed is greater than a preset value; and the second braking module is used for braking according to preset electric braking force and hydraulic braking force when the braking stroke sensor and/or the wheel speed sensor are in fault, and performing fault reminding.
An embodiment of a third aspect of the present application provides an electric vehicle including the brake device of the electric vehicle of the above embodiment.
The electric braking force adjusting device generates an adjusting value of electric braking force according to the actual deceleration of the electric vehicle, flexibly adjusts the electric braking force according to the adjusting value, and changes the total braking force through the adjustment of the electric braking force, so that the vehicle can obtain the same braking deceleration and braking feeling under the same brake pedal opening degree, and is not influenced by vehicle load and road conditions, so that more uniform braking effect can be obtained under different loads and road conditions, and the safety of braking and the braking experience of a driver are greatly improved. Therefore, the problems that the actual braking effect is different under the same opening degree and the same braking intention at present, the braking safety is reduced, the braking experience of a driver is reduced 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 flowchart of a braking method of an electric vehicle according to an embodiment of the present application;
FIG. 2 is a schematic structural diagram of a braking system of an electric vehicle according to an embodiment of the present application;
FIG. 3 is a flowchart of a braking method for an electric vehicle according to an embodiment of the present application
Fig. 4 is an exemplary diagram of a brake 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.
The braking force of the conventional electric automobile comprises hydraulic braking force and electric braking force for energy recovery, the hydraulic braking force under the same braking opening degree is difficult to change, and the strength of the electric braking force is basically a fixed value calculated according to the braking opening degree and a grade set by a driver. Therefore, the electric vehicle corresponds to the same hydraulic braking force and the same electric braking force under the same braking opening degree of the brake pedal, and the total braking force is the same, so the braking stroke and the total braking force are in one-to-one correspondence, but the braking stroke and the total braking force do not have one-to-one correspondence with the actual deceleration of the vehicle, the vehicle load is different, the uphill and downhill conditions are different, and the like, which all cause that the actual braking deceleration of the vehicle is different and the braking feeling is inconsistent under the same braking opening degree and braking intention by the driver, and are not favorable for the braking feeling.
Therefore, the embodiment of the application provides a braking method and a braking device of an electric vehicle and the electric vehicle. The following describes a braking method and device for an electric vehicle and the electric vehicle according to an embodiment of the present application with reference to the drawings. The application provides a braking method of an electric vehicle, which aims to solve the problems that the actual braking effect is different under the same opening degree and the same braking intention at present and the braking safety and the braking experience of a driver are reduced. Therefore, the problems that the actual braking effect is different under the same opening degree and the same braking intention at present, the braking safety is reduced, the braking experience of a driver is reduced and the like are solved.
Specifically, fig. 1 is a schematic flowchart of a braking method of an electric vehicle according to an embodiment of the present application.
As shown in fig. 1, the braking method of the electric vehicle includes the steps of:
in step S101, the current opening degree of the brake pedal of the electric vehicle is acquired.
The subject of execution of the braking method for an electric vehicle may be the electric vehicle. The braking method of the electric vehicle according to the embodiment of the present application may be performed by the braking device of the electric vehicle according to the embodiment of the present application, and the braking device of the electric vehicle according to the embodiment of the present application may be configured in any electric vehicle to perform the braking method of the electric vehicle according to the embodiment of the present application.
The electric vehicle is provided with hydraulic braking force and electric braking force, the hydraulic braking force corresponds to the braking stroke one by one and cannot be adjusted at will, but the electric braking force can be adjusted according to braking requirements and braking effects. In addition, different braking effects can be generated due to the fact that different braking openness corresponds to different braking forces, and therefore in order to accurately adjust the electric braking force, the current openness of the brake pedal is collected firstly in the embodiment of the application so as to be used for adjusting the electric braking force. The current opening degree of the brake pedal can be acquired through the brake opening degree sensor.
In step S102, a target deceleration of the electric vehicle is calculated according to the current opening degree, and a hydraulic braking force and an electric braking force of the brake system are determined according to the target deceleration.
It is understood that different braking forces may generate different decelerations, which correspond to braking forces, and thus embodiments of the present application may determine hydraulic braking force and electric braking force according to a target deceleration.
In the present embodiment, the target deceleration of the electric vehicle may be calculated according to various ways, and is not particularly limited herein.
As a possible implementation manner, calculating the target deceleration of the electric vehicle according to the current opening degree includes: generating a relation table of the opening degree and the deceleration according to preset brake preference; and searching an opening degree and deceleration relation table according to the current opening degree to obtain the target deceleration.
The preset braking preference is the braking intensity level required by the user, and can be generated by collecting the driving habits of the user, or generated according to the braking intensity level preference input by the user, and is not specifically limited herein. According to the embodiment of the application, the relation table of the opening degree and the deceleration can be generated in advance, so that the target deceleration can be rapidly and accurately acquired according to the current opening degree.
As another possible implementation manner, the embodiment of the present application may also determine the current braking demand according to the braking stroke, and determine the target deceleration on the premise of meeting the braking regulation and safety according to the braking strength level preference input by the driver.
In step S103, an adjustment value of the electric braking force is generated in accordance with the detected actual deceleration of the electric vehicle so that the actual deceleration is the same as the target deceleration, while braking based on the hydraulic braking force.
It can be understood that, the embodiment of the application can ensure that the brake deceleration and the brake feeling are the same under different vehicle-mounted and road conditions, has better brake consistency and greatly improves the brake safety.
In some embodiments, detecting an actual deceleration of the electric vehicle comprises: collecting pulse signals of a wheel speed sensor, and counting the number of the pulse signals in a first preset time; calculating the wheel speed of the wheels according to the number of the pulse signals, and calculating the average wheel speed of all the wheels; when the difference value between the wheel speed and the average wheel speed is larger than a first threshold value and the ratio of the difference value to the average wheel speed is larger than a second threshold value, judging that the wheel speed is not credible, and taking the average value of the residual wheel speeds as the actual vehicle speed; and calculating to obtain deceleration according to two adjacent actual vehicle speeds, and taking the average value of all decelerations in a second preset time as the actual deceleration.
The first threshold, the second threshold, the first preset time and the second preset time may be set according to actual conditions, and are not specifically limited herein. For example, the first threshold may be 5km/h or 6km/h, etc., the second threshold may be a ratio of 10% or 20%, etc., the first preset time may be 10ms or 20ms, etc., and the second preset time may be 100ms or 200ms, etc.
For example, the method comprises the steps of collecting wheel speed sensor pulse signals of four wheels once every 10ms, calculating each wheel speed and a first average wheel speed of the four wheels according to the number of pulses within 10ms, judging that the wheel speed is not credible when a certain wheel speed is less than or greater than the first average wheel speed by more than 10% and the difference between the wheel speed and the first average wheel speed is more than 5km/h, averaging the rest wheel speeds to obtain a second average wheel speed, and judging the second average wheel speed as the current actual vehicle speed; the time window of 100ms is taken as the time window for calculating the actual deceleration of the vehicle, and the average deceleration within 100ms is calculated as the real-time actual deceleration of the vehicle by using the determined vehicle speed.
It should be noted that, in the embodiments of the present application, the adjustment value of the electric braking force may also be generated in various ways, and is not limited in particular herein.
Calculating the difference between the actual deceleration and the target deceleration as a possible implementation; determining the adjusting time of the difference value according to the preset braking preference; and calculating to obtain an adjusting value according to the difference and the adjusting time. It can be understood that, the embodiment of the application can determine how fast the actual deceleration is adjusted to the target deceleration according to the preset braking preference, so as to determine the adjustment value, thereby improving the use experience of the user.
As another possible implementation manner, the embodiment of the present application may also rapidly adjust the magnitude of the electric braking force at a fixed period (for example, 10ms as a period) according to the actual deceleration and the target deceleration, increase the electric braking force when the actual deceleration is insufficient, and decrease the electric braking force when the actual deceleration is too large, so as to finally reach the target deceleration.
In some embodiments, further comprising: collecting the detection number of the brake stroke sensor voltage and the wheel speed sensor pulse signals; when the voltage is greater than or less than the rated voltage, judging that the brake stroke sensor has a fault; when the difference value between the detected number and the calibrated number corresponding to the wheel speed is greater than a preset value, judging that the wheel speed sensor has a fault; and if the brake stroke sensor has a fault and/or the wheel speed sensor has a fault, braking is carried out according to the preset electric braking force and the hydraulic braking force, and fault reminding is carried out.
The rated voltage is determined according to a brake stroke sensor, such as 0.2V-4.8V. The preset value and the preset electric braking force can be set according to actual conditions, and are not particularly limited herein.
For example, the voltage signal of the brake travel sensor is monitored in real time, and if the collected voltage is less than 0.2V or more than 4.8V, the short circuit or open circuit fault of the sensor is judged; monitoring pulse signals of the four wheel speeds in real time, and judging that the wheel speed sensor has faults when the number of the pulse signals is unreasonable or is not matched with other wheel speeds; when the faults occur, the electric braking force is not adjusted in real time according to the signals, the electric braking force is adjusted to a set fixed value, and a user is prompted on the instrument.
It should be noted that, in the embodiment of the present application, a braking system as shown in fig. 2 may be used for braking, wherein, to ensure braking safety, a vehicle controller is added to directly acquire a wheel speed sensor signal through a hard wire, determine a vehicle speed and an actual deceleration of the vehicle, and acquire a braking opening sensor and an accelerator sensor through a hard wire, so as to ensure stability and real-time performance of the signal, and calculate the vehicle speed through corresponding redundancy and a safety algorithm, so as to ensure reliability and stability of a core signal, i.e., the vehicle speed; then calculating the current deceleration of the vehicle in real time according to the vehicle speed; then acquiring the travel opening degree of the brake pedal pressed by the driver, judging the braking intention and demand, and determining the due target deceleration of the vehicle, wherein the driver can adjust the braking strength through an adjusting switch on the basis that the target deceleration meets the regulation; and finally, the electric braking force is adjusted through the real-time actual deceleration and the target deceleration of the vehicle, so that the braking deceleration of the vehicle is uniform and stable. In the whole control process, the states of a brake pedal travel sensor and a wheel speed sensor are monitored, if faults occur, relevant signals are not collected, and the default energy recovery intensity is used to ensure the braking safety.
The braking method of the electric vehicle will be further explained with reference to fig. 2 and 3, as shown in fig. 3, specifically as follows:
step 1, entering a state judgment process when a vehicle normally runs;
step 2, when the accelerator pedal is detected to be completely lifted and the opening of the brake pedal is larger than 5%, judging that the driver has a braking intention, controlling the vehicle to recover braking energy, and applying electric braking force;
step 3, if the condition in the step 2 is not met, the motor is not controlled to apply the electric braking force; executing the following process after judging that the electric braking force is applied;
step 4, judging the current braking requirement according to a braking travel sensor, and judging the target deceleration on the premise of meeting braking regulations and safety according to the braking strength grade preference input by a driver;
step 5, acquiring wheel speed sensor pulse signals of 4 wheels once every 10ms, calculating each wheel speed and a first average wheel of the 4 wheels according to the number of pulses within 10ms, judging that the wheel speed is not credible when a certain wheel speed is less than or greater than the first average wheel speed by more than 10% and the difference between the wheel speed difference and the first average wheel speed is more than 5km/h, averaging the other wheel speeds to obtain a second average wheel speed, and judging the second average wheel speed as the current actual vehicle speed;
step 6, taking 100ms as a time window for calculating the actual deceleration of the vehicle, and calculating the average deceleration within 100ms by using the determined vehicle speed as the real-time actual deceleration of the vehicle;
step 7, according to the actual deceleration and the target deceleration, the electric braking force is rapidly adjusted in a cycle of 10ms, when the actual deceleration is insufficient, the electric braking force is increased, when the actual deceleration is excessive, the electric braking force is reduced, and finally the target deceleration is achieved;
step 8, monitoring the voltage signal of the brake travel sensor in real time, and judging that the sensor is in short circuit or open circuit fault if the collected voltage is less than 0.2V or more than 4.8V; monitoring pulse signals of the four wheel speeds in real time, and judging that the wheel speed sensor has faults when the number of the pulse signals is unreasonable or is not matched with other wheel speeds;
and 9, when the faults occur, the electric braking force is not adjusted in real time according to the signals any more, the electric braking force is adjusted to a set fixed value, and a user is prompted on the instrument.
According to the braking method of the electric vehicle, the adjusting value of the electric braking force is generated according to the actual deceleration of the electric vehicle, the electric braking force is flexibly adjusted according to the adjusting value, and the total braking force is changed through adjustment of the electric braking force, so that the vehicle can obtain the same braking deceleration and braking feeling under the same opening degree of the brake pedal without being influenced by vehicle load and road conditions, more uniform braking effect can be obtained under different loads and road conditions, and the braking safety and the braking experience of a driver are greatly improved.
Next, a brake device of an electric vehicle proposed according to an embodiment of the present application is described with reference to the drawings.
Fig. 4 is a block schematic diagram of a brake device of an electric vehicle according to an embodiment of the present application.
As shown in fig. 4, the brake device 10 of the electric vehicle includes: an acquisition module 100, a determination module 200, and a first braking module 300.
The acquisition module 100 is used for acquiring the current opening degree of a brake pedal of the electric vehicle; the determining module 200 is used for calculating a target deceleration of the electric vehicle according to the current opening degree and determining hydraulic braking force and electric braking force of a braking system according to the target deceleration; the first brake module 300 is configured to generate an adjustment value of the electric braking force according to the detected actual deceleration of the electric vehicle so that the actual deceleration is the same as the target deceleration, while braking based on the hydraulic braking force.
Further, the first brake module 300 includes: the device comprises a first calculation unit, a determination unit and a determination unit. Wherein the first calculating unit is used for calculating the difference value between the actual deceleration and the target deceleration; the determining unit is used for determining the adjusting time of the difference value according to the preset braking preference; and the second calculating unit is used for calculating to obtain an adjusting value according to the difference value and the adjusting time.
Further, the determining module 200 includes: a generating unit and a table look-up unit. The generating unit is used for generating an opening degree and deceleration relation table according to preset brake preference; and the table look-up unit is used for looking up a relation table of the opening degree and the deceleration according to the current opening degree to obtain the target deceleration.
Further, the device of this application embodiment still includes: the device comprises a detection module, a fault determination module and a second braking module.
Wherein the detection module is used for detecting the actual deceleration of the electric vehicle and comprises: collecting pulse signals of a wheel speed sensor, and counting the number of the pulse signals in a first preset time; calculating the wheel speed of the wheels according to the number of the pulse signals, and calculating the average wheel speed of all the wheels; when the difference value between the wheel speed and the average wheel speed is larger than a first threshold value and the ratio of the difference value to the average wheel speed is larger than a second threshold value, judging that the wheel speed is not credible, and taking the average value of the residual wheel speeds as the actual vehicle speed; calculating to obtain deceleration according to two adjacent actual speeds, and taking the average value of all decelerations in a second preset time as the actual deceleration;
the fault determination module is used for acquiring the voltage of the brake travel sensor and the detection number of the pulse signals of the wheel speed sensor, determining the fault of the brake travel sensor when the voltage is greater than or less than the rated voltage, and determining the fault of the wheel speed sensor when the difference value between the detection number and the calibration number corresponding to the wheel speed is greater than a preset value;
and the second brake module is used for braking according to preset electric brake force and hydraulic brake force when the brake stroke sensor fails and/or the wheel speed sensor fails, and performing fault reminding.
It should be noted that the foregoing explanation of the embodiment of the braking method for an electric vehicle is also applicable to the braking device for an electric vehicle of this embodiment, and will not be described herein again.
According to the braking device of the electric vehicle, the adjusting value of the electric braking force is generated according to the actual deceleration of the electric vehicle, the electric braking force is flexibly adjusted according to the adjusting value, the total braking force is changed through the adjustment of the electric braking force, the vehicle can obtain the same braking deceleration and braking feeling under the same braking pedal opening degree and is not influenced by vehicle load and road conditions, more uniform braking effect can be obtained under different loads and road conditions, and the braking safety and the braking experience of a driver are greatly improved.
The present embodiment also provides an electric vehicle including the brake device of the electric vehicle as in the above embodiment. According to the electric vehicle of the embodiment of the application, the adjusting value of the electric braking force is generated according to the actual deceleration of the electric vehicle, the electric braking force is flexibly adjusted according to the adjusting value, and the total braking force is changed through the adjustment of the electric braking force, so that the vehicle can obtain the same braking deceleration and braking feeling under the same braking pedal opening degree, and is not influenced by vehicle load and road conditions, and therefore more uniform braking effect can be obtained under different loads and road conditions, and the safety of great braking and the braking experience of a driver are achieved.
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.
The logic and/or steps represented in the flowcharts or otherwise described herein, e.g., an ordered listing of executable instructions that can be considered to implement logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or N wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
It should be understood that portions of the present 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.
In addition, functional units in the embodiments of the present application may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may also be stored in a computer readable storage medium.
The storage medium mentioned above may be a read-only memory, a magnetic or optical disk, etc. Although embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present application, and that variations, modifications, substitutions and alterations may be made to the above embodiments by those of ordinary skill in the art within the scope of the present application.
Claims (10)
1. A braking method of an electric vehicle, characterized by comprising the steps of:
collecting the current opening degree of a brake pedal of the electric vehicle;
calculating a target deceleration of the electric vehicle according to the current opening degree, and determining a hydraulic braking force and an electric braking force of the braking system according to the target deceleration; and
while braking based on the hydraulic braking force, an adjustment value of the electric braking force is generated in accordance with the detected actual deceleration of the electric vehicle so that the actual deceleration is the same as the target deceleration.
2. The method according to claim 1, characterized in that the generating of the adjustment value of the electric braking force in accordance with the detected actual deceleration of the electric vehicle comprises:
calculating a difference between the actual deceleration and the target deceleration;
determining the adjusting time of the difference value according to a preset brake preference;
and calculating to obtain the adjusting value according to the difference and the adjusting time.
3. The method according to claim 1, wherein the calculating a target deceleration of the electric vehicle according to the current opening degree includes:
generating a relation table of the opening degree and the deceleration according to preset brake preference;
and searching the relation table of the opening degree and the deceleration according to the current opening degree to obtain the target deceleration.
4. The method of claim 1, wherein detecting an actual deceleration of the electric vehicle comprises:
collecting pulse signals of a wheel speed sensor, and counting the number of the pulse signals in a first preset time;
calculating the wheel speed of the wheels according to the number of the pulse signals, and calculating the average wheel speed of all the wheels;
when the difference value between the wheel speed and the average wheel speed is larger than a first threshold value and the ratio of the difference value to the average wheel speed is larger than a second threshold value, judging that the wheel speed is not credible, and taking the average value of the residual wheel speeds as the actual vehicle speed;
and calculating to obtain deceleration according to two adjacent actual vehicle speeds, and taking the average value of all decelerations in a second preset time as the actual deceleration.
5. The method of claim 1, further comprising:
collecting the detection number of the brake stroke sensor voltage and the wheel speed sensor pulse signals;
determining that the brake stroke sensor is faulty when the voltage is greater than or less than a rated voltage;
when the difference value between the detected number and the calibrated number corresponding to the wheel speed is greater than a preset value, judging that the wheel speed sensor has a fault;
and if the brake stroke sensor and/or the wheel speed sensor have faults, braking according to preset electric braking force and the hydraulic braking force, and performing fault reminding.
6. A brake device for an electric vehicle, characterized by comprising:
the acquisition module is used for acquiring the current opening degree of a brake pedal of the electric vehicle;
the determining module is used for calculating a target deceleration of the electric vehicle according to the current opening degree and determining a hydraulic braking force and an electric braking force of the braking system according to the target deceleration; and
the first braking module is used for generating an adjusting value of the electric braking force according to the detected actual deceleration of the electric vehicle while braking based on the hydraulic braking force, so that the actual deceleration is the same as the target deceleration.
7. The apparatus of claim 6, wherein the first braking module comprises:
a first calculation unit that calculates a difference between the actual deceleration and the target deceleration;
the determining unit is used for determining the adjusting time of the difference value according to preset brake preference;
and the second calculating unit is used for calculating the adjusting value according to the difference value and the adjusting time.
8. The method of claim 5, wherein the determining module comprises:
the generating unit is used for generating an opening degree and deceleration relation table according to preset brake preference;
and the table look-up unit is used for looking up the relation table of the opening degree and the deceleration according to the current opening degree to obtain the target deceleration.
9. The apparatus of claim 5, further comprising:
a detection module for detecting an actual deceleration of the electric vehicle, comprising: collecting pulse signals of a wheel speed sensor, and counting the number of the pulse signals in a first preset time; calculating the wheel speed of the wheels according to the number of the pulse signals, and calculating the average wheel speed of all the wheels; when the difference value between the wheel speed and the average wheel speed is larger than a first threshold value and the ratio of the difference value to the average wheel speed is larger than a second threshold value, judging that the wheel speed is not credible, and taking the average value of the residual wheel speeds as the actual vehicle speed; calculating according to two adjacent actual speeds to obtain deceleration, and taking the average value of all decelerations in a second preset time as the actual deceleration;
the fault determination module is used for acquiring the voltage of a brake travel sensor and the detection number of pulse signals of a wheel speed sensor, determining the fault of the brake travel sensor when the voltage is greater than or less than the rated voltage, and determining the fault of the wheel speed sensor when the difference value between the detection number and the calibration number corresponding to the wheel speed is greater than a preset value;
and the second braking module is used for braking according to preset electric braking force and hydraulic braking force when the braking stroke sensor and/or the wheel speed sensor are in fault, and performing fault reminding.
10. An electric vehicle characterized by comprising the brake apparatus of the electric vehicle according to any one of claims 6 to 9.
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