CN114889604A - Regenerative braking control method of hybrid power vehicle based on electronic hydraulic braking system - Google Patents

Abstract

The invention discloses a regenerative braking control method of a hybrid power vehicle based on an electronic hydraulic braking system, which comprises the following steps: judging whether to enter a regenerative braking mode or not based on the working condition of the vehicle, and distributing the electro-hydraulic braking force by the EHB after entering the regenerative braking working mode; judging whether the motor rotating speed signal shakes or not, and if so, filtering the motor rotating speed; calculating the actual feedback capacity of the motor based on the rotating speed and the state of the motor; calculating the anti-drag torque of the engine according to the torque of the generator and the gear signal; calculating the actual braking torque executed by the motor according to the electric braking torque distributed by the EHB, the actual feedback capacity of the motor and the anti-drag torque of the engine; according to the braking demand of the driver and the braking torque actually executed by the motor, the EHB and the motor execute corresponding braking torque. The regenerative braking control method of the hybrid electric vehicle based on the electronic hydraulic braking system can solve the problems of mismatching of braking intentions and torque control fluctuation in the regenerative braking process of the hybrid electric vehicle.

Description

Regenerative braking control method of hybrid power vehicle based on electronic hydraulic braking system

Technical Field

The invention relates to the technical field of hybrid vehicles, in particular to a regenerative braking control method of a hybrid vehicle based on an electronic hydraulic braking system.

Background

With the increasing development of modern technology, the conventional fuel oil vehicle consumes excessive energy. In the automotive field, the search for new power sources is an important issue. The emergence of hybrid vehicles has brought a new power source, and can also reduce vehicle energy consumption by realizing the regenerative braking function. The working mode is that when the vehicle brakes, the motor model is switched to a power generation mode, the kinetic energy of the vehicle is converted into electric energy to be stored in the battery, the energy consumption is reduced, and the endurance mileage of the vehicle is improved.

However, when the hybrid vehicle performs regenerative braking, the deceleration of the entire vehicle during regenerative braking does not match the driver's braking demand and torque control fluctuates due to fluctuations in the engine hysteresis torque and the motor rotation speed.

Therefore, a need exists for a regenerative braking control method for a hybrid vehicle based on an electro-hydraulic braking system.

Disclosure of Invention

The invention aims to provide a regenerative braking control method of a hybrid vehicle based on an electronic hydraulic braking system, which aims to solve the problems in the prior art and solve the problems of mismatching of braking intention and torque control fluctuation in the regenerative braking process of the hybrid vehicle.

The invention provides a regenerative braking control method of a hybrid power vehicle based on an electronic hydraulic braking system, which comprises the following steps:

step S1, obtaining vehicle working condition parameters, judging whether to enter a regenerative braking mode or not based on the obtained vehicle working condition parameters, if so, executing step S2, otherwise, executing step S10;

step S2, entering a regenerative braking working mode, and distributing the electro-hydraulic braking force by the electronic hydraulic braking system;

step S3, obtaining a motor rotating speed signal, judging whether the motor rotating speed signal shakes, if so, executing step S4, otherwise, executing step S5;

step S4, carrying out filtering optimization processing on the rotating speed of the motor;

step S5, calculating the actual feedback capacity of the motor based on the motor speed and the motor state after filtering;

step S6, calculating the anti-drag torque of the engine according to the torque of the generator and the gear signal;

step S7, calculating the braking torque which is actually required to be executed by the motor according to the electric braking torque distributed by the electronic hydraulic braking system, the actual feedback capacity of the motor and the anti-drag torque of the engine;

step S8, performing electro-hydraulic coordinated braking, and respectively executing corresponding braking torques by the electronic hydraulic braking system and the motor according to the braking demand of the driver and the braking torque actually required to be executed by the motor;

step S9, obtaining motor state parameters, and executing step S10 when the motor state is abnormal; otherwise, executing step S1;

and step S10, performing pure hydraulic braking.

The method for controlling regenerative braking of a hybrid vehicle based on an electro-hydraulic brake system as described above, wherein in step S1, the vehicle operating condition parameters include vehicle speed, wheel speed, SOC, engine torque, gear, brake switch, powertrain system status, chassis system status, accelerator pedal opening, braking requirement, vehicle speed validity, wheel speed validity, engine torque validity, gear validity, brake switch validity, powertrain system status validity, chassis system status validity, accelerator pedal opening validity, and braking requirement validity, if all the above signals satisfy the set conditions, the method enters into a regenerative braking mode, executes S2, and if at least one signal does not satisfy the set conditions, executes step S10.

The method for controlling regenerative braking of a hybrid vehicle based on an electronic hydraulic brake system as described above, wherein step S2 is preferably performed to enter a regenerative braking operation mode, and the electronic hydraulic brake system performs electro-hydraulic brake force distribution, specifically comprising:

the electronic hydraulic braking system distributes the electro-hydraulic braking torque according to the braking requirement of a driver and in an electric braking priority mode.

The method for controlling regenerative braking of a hybrid vehicle based on an electro-hydraulic brake system as described above, wherein step S3 is preferably to acquire a motor speed signal and determine whether the motor speed signal is jittered, and the method specifically includes:

and setting a motor rotating speed fluctuation threshold, and determining that the motor rotating speed signal shakes when the motor rotating speed exceeds the motor rotating speed fluctuation threshold.

The method for controlling regenerative braking of a hybrid vehicle based on an electronic hydraulic brake system as described above, wherein preferably, the step S4 of performing filter optimization on the rotation speed of the motor specifically includes:

and performing Kalman filtering processing on the rotating speed of the motor.

The regenerative braking control method for a hybrid vehicle based on an electro-hydraulic brake system as described above, wherein preferably, in said step S5, said motor states include motor speed, motor power limit, motor phase current limit and efficiency limit of the motor itself.

The method for controlling regenerative braking of a hybrid vehicle based on an electro-hydraulic brake system as described above, wherein preferably, the step S5 of calculating the actual feedback capacity of the motor based on the filtered rotation speed and state of the motor includes:

calculating a motor power limit value by the following formula:

wherein, T _p Representing motor torque, P _max Represents the maximum power of the motor, and omega represents the rotating speed of the motor;

calculating a motor phase current limit value by the following formula:

wherein, T _m Representing motor torque, K representing motor torque coefficient, I _max Represents the maximum current allowed;

calculating the efficiency limit of the motor by the following formula:

wherein, P _chr Indicating charging power, P _m Indicating mechanical input power, P, to the motor _r Indicating the internal resistance power consumption r _m Denotes the internal resistance value, T _m Representing motor torque, omega representing motor speed,

in the case of a speed determination, P _chr Is represented by T _m If the power is maximum, then there are:

and (4) obtaining a motor feedback capacity curve according to the formula (4).

The method for controlling regenerative braking of a hybrid vehicle based on an electro-hydraulic brake system as described above, wherein step S9 is preferably performed by obtaining a motor state parameter, and when the motor state is abnormal, step S10 is preferably performed, and specifically includes:

setting a preset motor torque following threshold value; and when the torque following amount exceeds the preset motor torque following threshold value, the regenerative braking mode is exited, pure hydraulic braking is carried out, and the step S10 is executed.

The invention provides a regenerative braking control method of a hybrid electric vehicle based on an electronic hydraulic braking system, which aims at the problem that the hybrid electric vehicle carries out regenerative braking based on the self characteristics of the hybrid electric vehicle, and can realize the compensation effect of electric braking torque on sudden change torque; the problems that the braking intention of the whole vehicle is not matched with the braking intention of a driver and the braking is not smooth due to the fact that the engine torque lag, gear change and rotating speed jitter exist in the regenerative braking of the hybrid power vehicle are solved, the whole vehicle braking is enabled to be closer to the real intention of the driver, the smoothness and the safety in the braking process are improved, and the smooth and comfortable regenerative braking performance can be achieved.

Drawings

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described with reference to the accompanying drawings, in which:

FIG. 1 is a flowchart of an embodiment of a method for controlling regenerative braking of a hybrid vehicle based on an electro-hydraulic braking system provided by the present invention;

FIG. 2 is a logic diagram of an embodiment of a hybrid vehicle regenerative braking control method based on an electro-hydraulic braking system provided by the present invention;

FIG. 3 is a regenerative braking distribution curve under ideal conditions;

FIG. 4 is a diagram illustrating the effect of the filtering optimization process of the motor speed;

FIG. 5 is a graph of motor feedback capability;

FIG. 6 is an engine anti-drag torque;

FIG. 7 is a schematic diagram of the abnormal regenerative braking mode switching of the electric machine.

Detailed Description

Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is in no way intended to limit the disclosure, its application, or uses. The present disclosure may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that: the relative arrangement of parts and steps, the composition of materials, numerical expressions and numerical values set forth in these embodiments are to be construed as merely illustrative, and not restrictive, unless specifically stated otherwise.

As used in this disclosure, "first", "second": and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element preceding the word covers the element listed after the word, and does not exclude the possibility that other elements are also covered. "upper", "lower", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.

In the present disclosure, when a specific component is described as being located between a first component and a second component, there may or may not be intervening components between the specific component and the first component or the second component. When it is described that a specific component is connected to other components, the specific component may be directly connected to the other components without having an intervening component, or may be directly connected to the other components without having an intervening component.

All terms (including technical or scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs unless specifically defined otherwise. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate.

At present, when a hybrid vehicle is subjected to regenerative braking control, because of the existence of two power sources of an engine and a motor, the fluctuation of the engine hysteresis moment and the motor rotating speed exists, the whole vehicle deceleration is not matched with the braking requirement of a driver and the torque control fluctuates in the regenerative braking process, and the smoothness and the comfort of the whole vehicle are poor.

The EHB is an electronic hydraulic brake system, can replace the traditional vacuum booster, accurately sense the weight and the urgency of a control pedal of a driver through a sensor arranged on the EHB, converts the weight and the urgency into electric signals to be transmitted to a control unit, controls the motor to actuate by the control unit, establishes corresponding brake pressure, and can receive the request of an external controller and establish corresponding brake pressure according to the request.

As shown in fig. 1 and fig. 2, the method for controlling regenerative braking of a hybrid vehicle based on an electronic hydraulic brake system provided in the present embodiment specifically includes the following steps in an actual implementation process:

and S1, acquiring vehicle working condition parameters, judging whether to enter a regenerative braking mode or not based on the acquired vehicle working condition parameters, if so, executing a step S2, otherwise, executing a step S10.

In step S1, the vehicle operating condition parameters include vehicle speed, wheel speed, SOC, engine torque, gear position, brake switch, power system state, chassis system state, accelerator pedal opening, braking requirement, vehicle speed validity, wheel speed validity, engine torque validity, gear position validity, brake switch validity, power system state validity, chassis system state validity, accelerator pedal opening validity, and braking requirement validity, if all the above signals satisfy the setting condition, the regenerative braking mode is entered, and step S2 is executed, and if at least one of the signals does not satisfy the setting condition, step S10 is executed. According to the signal, whether the current vehicle can enter a regenerative braking mode can be judged.

And step S2, entering a regenerative braking working mode, and distributing the electro-hydraulic braking force by the electronic hydraulic brake system (EHB).

Specifically, an electro-hydraulic brake system (EHB) distributes electro-hydraulic brake torque in an electric brake priority manner according to driver braking demand. After the vehicle enters the regenerative braking mode, the EHB performs electro-hydraulic braking force distribution based on the electric brake priority principle, as shown in fig. 3.

And step S3, acquiring a motor rotating speed signal, judging whether the motor rotating speed signal shakes, if so, executing step S4, otherwise, executing step S5.

Specifically, a motor speed fluctuation threshold value is set, and when the motor speed exceeds the motor speed fluctuation threshold value, the motor speed signal is determined to have jitter.

And step S4, carrying out filtering optimization processing on the motor rotating speed.

Specifically, kalman filter processing is performed on the motor rotation speed. After the distribution of the electro-hydraulic braking force is finished, the motor feedback capacity needs to be calculated through the motor rotating speed and the motor state, and due to the fact that the running working condition of the automobile is complex, the rotating speed signal may shake, optimization processing is conducted through Kalman filtering. As shown in fig. 4, the rotation speed signal is jittered in a certain range, and after passing through kalman filtering, the rotation speed signal is smoothed.

And step S5, calculating the actual feedback capacity of the motor based on the motor speed and the motor state after the filtering processing.

In the step S5, the motor status includes a motor speed, a motor power limit, a motor phase current limit, and an efficiency limit of the motor itself.

After the rotating speed signal is subjected to filtering optimization processing, a motor feedback capacity curve is calculated through the rotating speed of the motor, the power limit of the motor, the phase current limit of the motor and the self efficiency of the motor. The calculation process is as follows:

the motor power limit is calculated by the following equation:

wherein, T _p Representing motor torque, P _max Represents the maximum power of the motor, and omega represents the rotating speed of the motor;

the motor phase current limit is calculated by the following equation:

wherein, T _m Representing motor torque, K representing motor torque coefficient, I _max Represents the maximum current allowed;

the motor phase current limitation means that the motor phase current is influenced by an IGBT (insulated gate bipolar transistor) of a motor driver, the motor phase current cannot exceed a certain value, and otherwise, the risk of burning out the IGBT exists.

The self efficiency of the motor is limited:

wherein, P _chr Indicating charging power, P _m Indicating mechanical power input to the motor, P _r Indicating the internal resistance power consumption r _m Denotes the internal resistance value, T _m Representing motor torque, omega representing motor speed,

at a specific speed of rotation, P _chr Is represented by T _m If the power is maximum, then there are:

this results in a motor feedback capacity curve, as shown in fig. 5.

And step S6, calculating the anti-drag torque of the engine according to the torque of the generator and the gear signal.

In the braking process of the hybrid vehicle, the engine torque is reversely dragged, and when the vehicle is in different gears, the braking torques transmitted to the wheel sides are different in magnitude. The anti-drag torque is thus calculated in real time based on the current engine torque and gear, as shown in fig. 6.

And step S7, calculating the braking torque which is actually required to be executed by the motor according to the electric braking torque distributed by the electronic hydraulic braking system, the actual feedback capacity of the motor and the anti-drag torque of the engine.

And step S8, performing electro-hydraulic coordinated braking, and respectively executing corresponding braking torques by the electronic hydraulic braking system and the motor according to the braking demand of the driver and the braking torque actually required to be executed by the motor.

Step S9, obtaining motor state parameters, and executing step S10 when the motor state is abnormal; otherwise, step S1 is executed.

Specifically, a preset motor torque following threshold value is set; and when the torque following amount exceeds the preset motor torque following threshold value, the regenerative braking mode is exited, pure hydraulic braking is carried out, and the step S10 is executed.

In view of safety during execution of regenerative braking, the present invention introduces a target electric braking torque and actual electric braking torque follow-up condition monitoring strategy. And when the difference value between the target electric braking torque and the actual electric braking torque exceeds a certain threshold value, judging that the motor state is abnormal. At this point, the regenerative braking mode is exited and pure hydraulic braking is performed, as shown in FIG. 6.

And step S10, performing pure hydraulic braking.

The regenerative braking control method of the hybrid electric vehicle based on the electronic hydraulic braking system provided by the embodiment of the invention carries out regenerative braking on the hybrid electric vehicle based on the self characteristics of the hybrid electric vehicle, and can realize the compensation effect of the electric braking torque on the sudden change torque; the problems that the braking intention of the whole vehicle is not matched with the braking intention of a driver and the braking is not smooth due to the fact that the engine torque lag, gear change and rotating speed jitter exist in the regenerative braking of the hybrid power vehicle are solved, the whole vehicle braking is enabled to be closer to the real intention of the driver, the smoothness and the safety in the braking process are improved, and the smooth and comfortable regenerative braking performance can be achieved.

Thus, various embodiments of the present disclosure have been described in detail. Some details that are well known in the art have not been described in order to avoid obscuring the concepts of the present disclosure. It will be fully apparent to those skilled in the art from the foregoing description how to practice the presently disclosed embodiments.

Although some specific embodiments of the present disclosure have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It will be understood by those skilled in the art that various changes may be made in the above embodiments or equivalents may be substituted for elements thereof without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims (8)

1. A regenerative braking control method for a hybrid vehicle based on an electro-hydraulic braking system, comprising:

step S1, obtaining vehicle working condition parameters, judging whether to enter a regenerative braking mode or not based on the obtained vehicle working condition parameters, if so, executing step S2, otherwise, executing step S10;

step S2, entering a regenerative braking working mode, and distributing the electro-hydraulic braking force by the electronic hydraulic braking system;

step S3, obtaining a motor rotating speed signal, judging whether the motor rotating speed signal shakes, if so, executing step S4, otherwise, executing step S5;

step S4, carrying out filtering optimization processing on the rotating speed of the motor;

step S5, calculating the actual feedback capacity of the motor based on the motor speed and the motor state after filtering;

step S6, calculating the anti-drag torque of the engine according to the torque of the generator and the gear signal;

step S7, calculating the braking torque which is actually required to be executed by the motor according to the electric braking torque distributed by the electronic hydraulic braking system, the actual feedback capacity of the motor and the anti-drag torque of the engine;

step S8, performing electro-hydraulic coordinated braking, and respectively executing corresponding braking torques by the electronic hydraulic braking system and the motor according to the braking demand of the driver and the braking torque actually required to be executed by the motor;

step S9, obtaining motor state parameters, and executing step S10 when the motor state is abnormal; otherwise, executing step S1;

and step S10, performing pure hydraulic braking.

2. The regenerative braking control method of a hybrid vehicle based on an electro-hydraulic braking system of claim 1, wherein in the step S1, the vehicle operating condition parameters include vehicle speed, wheel speed, SOC, engine torque, gear, brake switch, powertrain system state, chassis system state, accelerator pedal opening, braking demand, vehicle speed validity, wheel speed validity, engine torque validity, gear validity, brake switch validity, powertrain system state validity, chassis system state validity, accelerator pedal opening validity and braking demand validity, if all of the above signals satisfy a set condition, the regenerative braking mode is entered, S2 is executed, and if at least one of the signals does not satisfy the set condition, step S10 is executed.

3. The regenerative braking control method for the hybrid electric vehicle based on the electronic hydraulic braking system as claimed in claim 1, wherein the step S2 is entered into a regenerative braking operation mode, and the electronic hydraulic braking system performs electro-hydraulic braking force distribution, specifically comprising:

the electronic hydraulic braking system distributes the electro-hydraulic braking torque according to the braking requirement of a driver and in an electric braking priority mode.

4. The method for controlling regenerative braking of a hybrid vehicle according to claim 1, wherein the step S3 of obtaining a motor speed signal and determining whether the motor speed signal is jittered specifically comprises:

and setting a motor rotating speed fluctuation threshold, and determining that the motor rotating speed signal shakes when the motor rotating speed exceeds the motor rotating speed fluctuation threshold.

5. The regenerative braking control method for the hybrid electric vehicle based on the electro-hydraulic braking system according to claim 1, wherein the step S4 of performing filtering optimization processing on the rotation speed of the motor specifically comprises:

and performing Kalman filtering processing on the rotating speed of the motor.

6. The electro-hydraulic brake system-based hybrid vehicle regenerative braking control method according to claim 1, wherein in said step S5, said motor states include motor speed, motor power limit, motor phase current limit, and efficiency limit of the motor itself.

7. The method of claim 6, wherein the step S5 of calculating the actual feedback capacity of the electric motor based on the filtered rotation speed and state of the electric motor comprises:

calculating a motor power limit value by the following formula:

wherein, T _p Representing motor torque, P _max Represents the maximum power of the motor, and omega represents the rotating speed of the motor;

calculating a motor phase current limit value by the following formula:

wherein, T _m Representing motor torque, K representing motor torque coefficient, I _max Represents the maximum current allowed;

calculating the efficiency limit of the motor by the following formula:

wherein, P _chr Indicating charging power, P _m Indicating mechanical power input to the motor, P _r Indicating the internal resistance power consumption r _m Indicating internal resistanceValue, T _m Representing motor torque, omega representing motor speed,

in the case of a speed determination, P _chr Is represented by T _m If the power is maximum, then there are:

and (4) obtaining a motor feedback capacity curve according to the formula (4).

8. The regenerative braking control method for hybrid electric vehicle based on electro-hydraulic braking system as claimed in claim 1, wherein said step S9 is to obtain the motor status parameter, and when the motor status is abnormal, the step S10 is executed, specifically comprising:

setting a preset motor torque following threshold value; and when the torque following amount exceeds the preset motor torque following threshold value, the regenerative braking mode is exited, pure hydraulic braking is carried out, and the step S10 is executed.

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