CN109747624B

CN109747624B - Start-stop control system of hybrid electric vehicle

Info

Publication number: CN109747624B
Application number: CN201811489897.3A
Authority: CN
Inventors: 郑俊生; 郭鑫; 秦楠; 巩瑞奇; 戴宁宁; 田家印
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2018-12-06
Filing date: 2018-12-06
Publication date: 2020-07-28
Anticipated expiration: 2038-12-06
Also published as: CN109747624A

Abstract

The invention relates to a hybrid electric vehicle start-stop control system, which comprises a transmission device: to transmit power to the drive wheel; the prime power subsystem: the system is a power system of a raw fuel vehicle, is used for generating source power and is connected with a transmission device through a modified power subsystem; refitting a power subsystem: the hybrid power automobile is used for realizing the starting and stopping of the hybrid power automobile and the hybrid power driving; a controller: the integrated hybrid electric vehicle start-stop control method comprises the steps of collecting input signals through a sensor, judging and controlling a prime power subsystem and a modified power subsystem according to a set condition range, and enabling the hybrid electric vehicle to enter a braking energy recovery mode, a driving mode, an active sliding mode or a neutral sliding mode. Compared with the prior art, the invention has the advantages of convenient modification, low cost, maximized dynamic property and economy and the like.

Description

Start-stop control system of hybrid electric vehicle

Technical Field

The invention relates to the field of hybrid electric vehicle control, in particular to a hybrid electric vehicle start-stop control system.

Background

with the rapid development of economy and the acceleration of urbanization process, the world is under double pressure of solving energy crisis and governing environmental pollution, among all fossil energy consumption, the proportion of energy consumption generated in the field of transportation is very high, wherein the road transportation field is the main body with the largest energy consumption and emission (more than 70 percent) and fastest growth in various transportation modes, and is the primary air pollution source in large cities, so increasingly strict environmental protection and emission regulations put forward higher requirements for energy conservation and emission reduction of automobiles.

The main problems of the existing hybrid electric vehicle start-stop system are as follows: (1) the existing vehicle type can not be directly modified, and the hybrid power and start-stop functions are realized; (2) the method needs to be realized on the existing hybrid electric vehicle, the development period of the whole hybrid electric vehicle is long, and the cost of a redevelopment production platform is high; (3) the hybrid electric vehicle power system and the transmission system of the application object are complex and have high production cost.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a hybrid electric vehicle start-stop control system.

The purpose of the invention can be realized by the following technical scheme:

A hybrid vehicle start-stop control system, comprising:

The transmission device comprises: to transmit power to the drive wheel;

The prime power subsystem: the system is a power system of a raw fuel vehicle, is used for generating source power and is connected with a transmission device through a modified power subsystem;

Refitting a power subsystem: the hybrid power automobile is used for realizing the starting and stopping of the hybrid power automobile and the hybrid power driving;

A controller: the integrated hybrid electric vehicle start-stop control method comprises the steps of collecting input signals through a sensor, judging and controlling a prime power subsystem and a modified power subsystem according to a set condition range, and enabling the hybrid electric vehicle to enter a braking energy recovery mode, a driving mode, an active sliding mode or a neutral sliding mode.

The modified power subsystem comprises a 48V power supply, an ISG motor and a first clutch which are connected in sequence.

The prime power subsystem comprises an engine, a second clutch and a transmission, wherein the engine, the second clutch, the first clutch, the transmission and the transmission are sequentially connected, and the engine is a gasoline engine or a diesel engine.

A start-stop control method for a hybrid electric vehicle comprises the following steps:

1) Reading the current running state signal of the hybrid electric vehicle through a sensor to obtain the running state of the hybrid electric vehicle;

2) According to the received running state signal of the hybrid electric vehicle, the controller determines the running modes of the hybrid electric vehicle, including a braking energy recovery mode, a driving mode, an active coasting mode and a neutral coasting mode, and specifically comprises the following steps:

21) Judging whether the driver steps on the brake, if so, executing a step 24), and if not, executing a step 22);

22) Judging whether the throttle signal is larger than a set value, if so, executing a step 25, and if not, executing a step 23);

23) Judging whether the accelerator signal, the SoC signal of the 48V power supply and the vehicle speed signal are all in a set range, if so, executing the step 26), and if not, executing the step 27);

24) Acquiring the current rotation speed and gear position of the ISG motor, entering a braking energy recovery mode, engaging the first clutch, disengaging the second clutch, closing the engine, dragging the ISG motor by the wheels through the transmission device, and returning to the step 21);

25) Entering a driving mode, judging whether the current vehicle speed and the SoC signal of the 48V power supply are both in a set range, if so, executing a step 28), and if not, executing a step 29);

26) Entering an active sliding mode, engaging the first clutch, disengaging the second clutch, closing the engine, starting the ISG motor, and returning to the step 21);

27) Entering a neutral gear sliding mode, separating the first clutch, engaging the second clutch, closing the engine, dragging the ISG motor by the engine reversely, and returning to the step 21);

28) Engaging the first clutch, disengaging the second clutch, closing the engine, starting the ISG motor and returning to the step 21);

29) Engaging the first clutch, engaging the second clutch, starting the engine, starting the ISG motor, and returning to step 21).

In the step 1), the running state signals comprise an accelerator signal, a brake signal, a 48V power supply SoC signal of a BMS system, a current vehicle speed signal, an engine rotating speed signal, an ISG rotating speed signal and a current gear signal.

When the hybrid electric vehicle runs in a braking energy recovery mode, if the whole vehicle is in emergency braking or the power supply SoC is higher than a set threshold value, the connection of the ISG motor is disconnected, and the braking energy recovery is stopped.

The set threshold is 60%.

When the hybrid electric vehicle runs in a driving mode and is in a common driving mode of the engine and the ISG motor:

When the vehicle runs normally, the controller controls the engine to work in an economic area, and insufficient torque is provided by the ISG;

When the power supply SoC is insufficient to maintain ISG operation, the controller controls the engine to operate in an engine-only mode.

When the hybrid electric vehicle runs in the active coasting mode, when the power supply SoC is lower than a set threshold value, the engine is controlled to drag the ISG for power generation.

The set threshold is 50%.

Compared with the prior art, the invention has the following advantages:

1) The invention can be additionally modified into a hybrid electric vehicle with a start-stop technology on the basis of basically reserving the configuration of the traditional fuel vehicle, almost reserves the original power system, and has certain improvement effect on the power performance while giving consideration to low emission and high economy.

2) Compared with a direct hybrid electric vehicle, the hybrid electric vehicle modified by the method has low modification cost, and the total cost is far lower than that of the direct hybrid electric vehicle.

3) The starting and stopping control is carried out under four working conditions, so that the power performance and the economical efficiency of the device can be optimized to the maximum extent. The driving mode can reduce fuel consumption while ensuring dynamic performance, the braking energy recovery mode can fully utilize energy consumption during braking, the active sliding mode is favorable for improving the stability of high-speed cruising, and the neutral sliding mode is favorable for recovering parking kinetic energy.

Drawings

Fig. 1 is a schematic diagram of the structure of the present invention.

Fig. 2 is a schematic diagram of the control system of the present invention.

FIG. 3 is a flow chart of a control method of the present invention.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments without departing from the spirit and scope of the invention.

Examples

Fig. 1 is a schematic structural diagram of a low-mix vehicle according to an embodiment of the present invention. As shown in fig. 1, the main components of the mild hybrid vehicle include a second clutch 1, a first clutch 2, a transmission 3, a transmission 4, an engine 5, an ISG motor 6, a 48V power source 7,

wheels

8a and 8b, and a controller 30, wherein a retrofit power subsystem 10 includes the 48V power source 7, the ISG motor 6, and the first clutch 2. The prime mover subsystem includes the engine 5, the second clutch 1 and the transmission 3.

The weakly-mixed automobile adopted in the embodiment is obtained by modifying an original traditional fuel oil vehicle, the motive power subsystem 20 is reserved, the modified power subsystem 10 is mainly added, and the controller 30 is respectively connected with the modified power subsystem 10 and the motive power subsystem 20 through buses, so that the bidirectional transmission of electric signals can be realized. In this embodiment, the output shaft of the engine 5 transmits power to the first clutch 2 through the second clutch 1, and the first clutch 2 is connected to the transmission 3 and the transmission 4 in turn, and transmits power to the

wheels

8a and 8 b. The 48V power supply 7 is formed by combining a plurality of super capacitors and is electrically connected with the ISG motor 6 and can conduct bidirectional current. The ISG motor 6 is connected with the

wheels

8a and 8b through the first clutch 2, the transmission 3 and the transmission 4 in sequence, and can realize the bidirectional transmission of power between the

wheels

8a and 8b and the ISG 6.

Fig. 2 is a schematic diagram of a control system of a start-stop system of a mild hybrid vehicle according to an embodiment of the present invention. The system mainly comprises a 48V system start-stop controller 201, an input signal 220 and an output signal 230. The input signals 220 include a throttle signal 202, a brake signal 203, a 48V power supply SoC signal 204, a vehicle speed signal 205, an engine speed signal 206, an ISG speed signal 207, and a gear signal 208. The output signals include an engine torque signal 209, an engine start stop signal 210, an ISG torque signal 211, a brake pressure signal 212, a second clutch engagement signal 213, and a first clutch engagement signal 214.

In the running process of the weak hybrid vehicle of the embodiment, the 48V system start-stop controller 201 continuously reads an accelerator signal 202 and a brake signal 203 generated by the operation of a driver, a 48V power supply SoC signal 204 from the BMS system, a current vehicle speed signal 205 acquired by a vehicle speed sensor, an engine speed signal 206 transmitted by an internal engine speed sensor, an ISG speed signal 207 transmitted by a motor speed sensor and a current gear signal 208 transmitted by a transmission gear sensor, and can automatically judge and switch among four modes of a driving mode, a braking energy recovery mode, an active coasting mode and a neutral coasting mode by an energy management method in the 48V system start-stop controller 201, and output control signals. The output engine torque signal 209 and the engine start-stop signal 210 are sent to an engine control unit, and the engine is controlled to output the set torque and start-stop respectively; the output ISG torque signal 211 is sent to a motor control unit to control the ISG to generate a set torque; the output brake pressure signal 212 is sent to a brake control unit to control the brake to generate a corresponding brake torque; the output clutch 1 combination signal 213 is sent to the control unit of the clutch 1 to control the combination and separation of the clutch 1; the output clutch 2 engagement signal 214 is sent to the control unit of the clutch 2 to control the engagement and disengagement of the clutch 2.

Fig. 3 is a flowchart of a control method of a start-stop system of a mild hybrid vehicle according to an embodiment of the present invention. As shown in fig. 3, the method for controlling the start-stop system of the mild hybrid vehicle according to the embodiment of the present invention includes the following steps:

S301, acquiring a current accelerator signal, a brake signal, an SoC signal of a 48V power supply and a vehicle speed signal, and transmitting the signals to a 48V start-stop controller.

And S302, judging whether the driver steps on the brake. If yes, go to step S305; if not, step S303 is performed.

And S303, judging whether the throttle signal is larger than a set value or not. If yes, executing step S306; if not, step S304 is performed.

S304, judging whether the accelerator signal, the SoC signal of the 48V power supply and the vehicle speed signal are all in a set range, for example, the accelerator is less than 20%, the SoC is more than 50% and the vehicle speed is less than 60km/h, if so, executing a step S307; if not, step S308 is performed.

S305, acquiring the rotating speed of the current ISG motor and the gear of the gearbox.

S306, enter the driving mode.

And S307, entering an active sliding mode.

And S308, entering a neutral coasting mode.

And S309, entering a braking energy recovery mode.

S310, judging that the current vehicle speed and the SoC signal of the 48V power supply are both in a set range, for example, the vehicle speed is less than 10km/h and the SoC is more than 55%, if so, executing a step S314; if not, step S315 is performed.

And S311, engaging the first clutch 2, disengaging the second clutch 1, turning off the engine and turning on the ISG motor.

S312, the first clutch 2 is separated, the second clutch 1 is connected, the engine is turned off, and the engine drags the ISG motor backwards.

And S313, engaging the first clutch 2, disengaging the second clutch 1, turning off the engine, and dragging the ISG motor by the wheels through the transmission device.

And S314, engaging the first clutch 2, disengaging the second clutch 1, turning off the engine and turning on the ISG motor.

And S315, engaging the first clutch 2, engaging the second clutch 1, starting the engine and starting the ISG motor.

In this embodiment, the energy management strategy covers four modes, namely a braking energy recovery mode, a driving mode, an active coasting mode and a neutral coasting mode. In the braking energy recovery mode, the first clutch 2 is connected, the second clutch 1 is separated, the engine is turned off, the vehicle is in a braking state at the moment, the wheels drag the ISG motor to rotate through the transmission mechanism, and the 48V power supply is charged when the conditions are met. The ISG motor provides required partial braking torque while reversing, and the automobile braking is assisted. In a driving mode, when the vehicle speed and the SoC of a 48V power supply are both in a set range, the first clutch 2 is engaged, the second clutch 1 is disengaged, the engine is closed, the ISG motor is started, and the ISG motor drives the vehicle to run, belonging to pure electric driving; when the vehicle speed and the SoC of the 48V power supply are not all in the set range, the first clutch 2 is engaged, the second clutch 1 is engaged, and the engine and the ISG motor are started simultaneously, belonging to hybrid power drive. If the SoC of the 48V power supply is not in the range, the engine can drag the ISG motor to charge the 48V power supply. If the SoC of the 48V power supply is sufficient, the engine can be ensured to be in the most economic operation condition by adjusting the ISG torque, and the oil consumption is reduced. In the active coasting mode, the first clutch 2 is engaged, the second clutch 1 is disengaged, the engine is turned off, and the ISG motor is turned on. The driver does not step on the accelerator and the brake, and the ISG motor is used for driving the vehicle at the moment, so that the speed of the vehicle can be maintained to be stable in the state. In the neutral coasting mode, the first clutch 2 is disengaged, the second clutch 1 is engaged, the engine is turned off, the vehicle is in a free-wheeling state, and the engine can drag the ISG motor to generate power.

In conclusion, the fuel oil vehicle can be directly applied to a traditional fuel oil vehicle, is modified into a hybrid electric vehicle with a start-stop technology, almost reserves an original power system, and has certain improvement effect on the power performance while considering low emission and high economy.

The foregoing detailed description is of the invention with reference to examples, which are not intended to limit the scope of the invention and its legal protection. Those skilled in the art should recognize that they can make various changes, substitutions and alterations herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A hybrid electric vehicle start-stop control system is characterized by comprising:

Transmission (4): to transmit power to the drive wheel;

Prime mover subsystem (20): the system is a power system of a crude fuel vehicle, is used for generating source power and is connected with a transmission device (4) through a modified power subsystem (10), the prime power subsystem (20) comprises an engine (5), a second clutch (1) and a speed changer (3), the engine (5), the second clutch (1), a first clutch (2), the speed changer (3) and the transmission device (4) are sequentially connected, and the engine (5) is a gasoline engine or a diesel engine;

Retrofit power subsystem (10): the modified power subsystem (10) comprises a 48V power supply (7), an ISG motor (6) and a first clutch (2) which are sequentially connected;

Controller (30): the integrated hybrid electric vehicle start-stop control method comprises the steps of collecting input signals through a sensor, judging and controlling a prime power subsystem (20) and a modified power subsystem (10) according to a set condition range, and enabling the hybrid electric vehicle to enter a braking energy recovery mode, a driving mode, an active sliding mode or a neutral sliding mode;

The start-stop control method applying the hybrid electric vehicle start-stop control system comprises the following steps:

2. The start-stop control system of a hybrid electric vehicle according to claim 1, wherein in the step 1), the operation state signals comprise an accelerator signal, a brake signal, a 48V power supply SoC signal of a BMS system, a current vehicle speed signal, an engine speed signal, an ISG speed signal and a current gear signal.

3. The start-stop control system for the hybrid electric vehicle as claimed in claim 1, wherein when the hybrid electric vehicle is operating in the braking energy recovery mode, if the whole vehicle is in emergency braking or the SoC of the power supply is higher than a set threshold, the connection of the ISG motor is disconnected, and the braking energy recovery is stopped.

4. The start-stop control system for the hybrid electric vehicle as claimed in claim 3, wherein the set threshold is 60%.

5. The start-stop control system for the hybrid electric vehicle as claimed in claim 1, wherein when the hybrid electric vehicle is operated in a driving mode and the engine and the ISG motor are driven together:

6. The start-stop control system for the hybrid electric vehicle as claimed in claim 1, wherein when the hybrid electric vehicle runs in an active coasting mode, the engine is controlled to pull the ISG backward to generate power when the power supply SoC is lower than a set threshold.

7. The start-stop control system for the hybrid electric vehicle as claimed in claim 6, wherein the set threshold is 50%.