KR101944310B1 - Coasting and regenerative braking control method of four-wheel drive hybrid vehicle - Google Patents

Abstract

The present invention relates to a coasting and regenerative braking control method of a four-wheel drive hybrid vehicle to optimize costing and regenerative braking according to a distance from a forward object in a four-wheel drive hybrid vehicle equipped with a 48V belt-driven starter generator (BSG) motor mounted on an engine belt of a front wheel and a rear wheel motor mounted on a rear wheel axle, the method includes the steps of: entering a coasting section if a distance from a forward object is equal to or less than a predetermined distance when an accelerator pedal is not operated during traveling; performing the regenerative braking using only a rear wheel motor when the distance from the forward object is a distance required for starting a regenerative braking during coasting; generating braking pressure by driving a clutch and an engine when hydraulic brake pressure reaches a required point; performing regenerative braking using a front wheel motor when the regenerative braking of the front wheel motor is available while continuously performing the regenerative braking using only the rear wheel motor; and stopping the regenerative braking of the front/rear wheel motors when the hydraulic brake is actuated.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-wheel drive hybrid vehicle,

The present invention relates to a method of controlling a coasting and regenerative braking of a four-wheel-drive hybrid vehicle, and more particularly, to a method of controlling a four-wheel drive hybrid vehicle using a 48V BSG (Belt-driven Starter Generator) motor mounted on a front- And more particularly to a method of controlling a four-wheel drive hybrid vehicle in which the costing and regenerative braking are optimized in accordance with the distance from a forward object in a four-wheel drive hybrid vehicle equipped with a rear wheel motor.

An electric vehicle is an automobile that can use electric energy stored in a battery as a power source. In order to improve the energy efficiency and mileage of the electric vehicle, a regenerative braking system capable of recovering a part of the braking energy as electric energy during braking of the electric vehicle is provided, Is controlled.

BACKGROUND ART [0002] Conventional electric vehicles mainly include an automatic transmission or a continuously variable transmission (CVT).

When the manual transmission is mounted on the electric vehicle, the driver directly operates the clutch, so that the driver feels sensitive to the vehicle behavior by the regenerative braking control. Therefore, regenerative braking must be precisely controlled in the case of an electric vehicle equipped with a manual transmission.

A four-wheel-drive powertrain that can apply a driving force to both the front wheel and the rear wheel has several advantages. This advantage is still valid when a powertrain of an electric vehicle is configured by a four-wheel drive system.

However, when the manual transmission is mounted on the power train of the four-wheel-drive system, the speed change stage is arbitrarily operated by the driver.

At this time, since only one deceleration is applied to the rear wheels, when the rear wheel motor is driven by the same regenerative braking torque, the same regenerative braking torque is applied to the rear wheels. However, the deceleration ratios of the front wheels are applied differently for each gear stage depending on the state of operation of the driver. Therefore, even if the regenerative braking torque for driving the front wheel motor is the same, the regenerative braking torque applied to the front wheels differs when the speed change stage is different.

If the regenerative braking torque applied to the front wheels changes as the speed change stage is changed in consideration of the fact that the vehicle can run at various speeds even at the same speed, there is a risk that the stability of the vehicle behavior may be impaired.

In order to prevent the stability of the vehicle behavior caused by the difference of the regenerative braking torque from being threatened, a technique proposed in the prior art is disclosed in Patent Document 1 below.

The prior art disclosed in Patent Document 1 controls the regenerative braking of the front wheel motor on the basis of the current speed change stage and the current vehicle speed when the brakes of the four-wheel drive electric vehicle operate, thereby achieving a target regenerative power The target braking power for the front wheels is realized at a preferable value regardless of the speed change stage.

Korean Patent Laid-Open No. 10-2005-0119989 (Dec. 22, 2005) (Regenerative braking control method and system for four-wheel drive electric vehicle)

However, although the conventional four-wheel-drive hybrid vehicle and the conventional technology have an advantage in that the regenerative braking can be controlled in consideration of the speed change stage of the transmission, stable coasting control is not possible and the regenerative braking It is also impossible to optimize.

Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the conventional four-wheel-drive mild hybrid vehicle and the related art, and it has been proposed to use a 48V BSG (Belt-driven Starter Generator) motor mounted on a front- It is an object of the present invention to provide a method of controlling a four-wheel drive hybrid vehicle in which a four-wheel drive hybrid vehicle equipped with a rear wheel motor is optimized for a running distance and a regenerative braking distance in accordance with a distance to a forward object .

In order to achieve the above object, a method of controlling a four-wheel drive hybrid vehicle according to the present invention comprises the steps of: (a) detecting a distance to a forward object when the accelerator pedal is not operated during traveling, And if the distance to the object is less than a predetermined distance, entering a course section; (b) performing regenerative braking using only the rear wheel motor if the distance from the forward object during the course of the course is a distance at which regenerative braking should be started; (c) generating a brake pressure by driving the clutch and the engine when a hydraulic brake pressure reaches a required time during the execution of the regenerative braking as in the step (b); (d) performing regenerative braking using the front wheel motor when the regenerative braking of the front wheel motor is possible by confirming the possibility of regenerative braking of the front wheel motor while continuously performing regenerative braking only using the rear wheel motor only after the step (c); (e) stopping regenerative braking of the front wheel / rear wheel motor when the hydraulic brakes are operated after step (d).

Wherein the step (a) comprises the steps of: (a1) confirming whether the accelerator pedal value is "0" while the vehicle is running; (a2) If the accelerator pedal value is "0 ", the distance to the forward object is measured, and if the measured distance from the forward object is less than a predetermined distance, turning off the engine and the clutch, .

The step (b) includes the steps of: (b1) confirming the distance between the current vehicle speed and the forward object if the distance to the forward object is the distance at which the regenerative braking should start; (b2) calculating a maximum regenerative braking power; (b3) calculating power acceptable for the battery; (b4) calculating a real time optimal regenerative braking power based on the maximum regenerative braking power and the battery accommodatable power; (b5) controlling the rear wheel motor based on the calculated optimum regenerative braking power to start regenerative braking.

The step (d) includes the steps of: (d1) confirming the distance between the current vehicle speed and the forward object while performing the regenerative braking continuously using only the rear wheel motor; (d2) calculating a maximum regenerative braking power; (d3) calculating a battery acceptable power; (d4) calculating a real-time optimal regenerative braking power based on the maximum regenerative braking power and the battery accommodatable power.

According to the present invention, in a four-wheel drive hybrid vehicle equipped with a 48-volt BSG (Belt-driven Starter Generator) motor mounted on an engine belt of a front wheel and a rear wheel motor mounted on a rear wheel shaft, a costing and regenerative braking And it is advantageous to realize stabilized regenerative braking in consideration of the gear position of the transmission.

Further, according to the present invention, there is an effect that the fuel economy can be improved by minimizing the period in which the regenerative braking is maximized with the rear-wheel motor and the engine is turned on.

1 is a configuration diagram of a four-wheel drive hybrid vehicle to which the method of controlling a running and regenerative braking according to the present invention is applied;
FIG. 2 is a diagram showing an example of a section for controlling the costing and regenerative braking in the present invention,
3 is a flowchart showing a method for controlling a running and regenerative braking of a four-wheel drive hybrid vehicle according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for controlling a running and regenerative braking of a four-wheel drive hybrid vehicle according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic block diagram of a four-wheel-drive hybrid vehicle to which a method for controlling a running and regenerative braking of a four-wheel drive hybrid vehicle according to a preferred embodiment of the present invention is applied.

The four wheel drive hybrid vehicle 100 to which the present invention is applied includes a front wheel 101 and a rear wheel 102, a brake apparatus for applying a mechanical braking force to the front wheel 101 and the rear wheel 102, (103).

A front motor 104 for applying a driving force and a regenerative braking force to the front wheel 101, a rear motor 104 for applying a driving force and a regenerative braking force to the rear wheel 102, (105). A manual transmission interposed between the front wheel 104 and the front wheel 101 is provided.

The present invention can be applied not only to a manual transmission but also to an automatic transmission. In the case of an automatic transmission, when it is determined that regenerative braking is possible in a front wheel motor, a clutch of the automatic transmission is engaged, It is possible to perform regenerative braking of the front wheel motor by selecting the number of gears on the table.

A vehicle speed detector for detecting a vehicle speed, a brake operation detector for detecting the operation amount and the operation amount of the brake device 103, a brake operation detector for detecting the operation amount of the brake device 103, A front wheel speed detector for detecting the wheel speed of the rear wheel 102, a rear wheel speed detector for detecting the wheel speed of the rear wheel 102, speed shift detector for detecting a shift-speed.

The hybrid control device 106 is a controller for controlling the regenerative braking of the front wheel motor 104 and the rear wheel motor 105 on the basis of signals detected from the respective detectors.

The hybrid control apparatus 106 may be implemented by one or more microprocessors operating according to a set program, and the set program may be implemented by performing the steps included in the costing and regenerative braking control method of the embodiment of the present invention And the like.

In addition, the four-wheel drive hybrid vehicle 100 to which the present invention is applied includes an engine control unit (ECU) for controlling the engine and a brake control unit (BCU) for controlling the hydraulic braking force. It is preferable that the respective controllers communicate with each other via CAN communication.

The four wheel drive hybrid vehicle 100 to which the present invention is applied includes a first inverter 108 for charging a high voltage battery built in the battery management system 109 with the power generated by the front wheel motor 104, A second inverter 110 for charging the high voltage battery built in the battery management system 109 with the power generated by the high voltage battery in the battery management system 109, And a converter 111.

The configuration of the vehicle is the same as that of a general four-wheel-drive hybrid vehicle. The present invention is characterized in that a distance measuring unit 107 for measuring a distance to a forward object is added to the above configuration. And may include a front object, a front vehicle, a traffic light, a person, and the like.

FIG. 3 is a flowchart showing a method for controlling a running and regenerative braking of a four-wheel drive hybrid vehicle according to the present invention, wherein (a) if the accelerator pedal is not operated during traveling, the distance to a forward object is detected, (S101 to S106); (b) when the distance from the forward object during the course of the costing is a distance that the regenerative braking should be started, regenerative braking is performed using only the rear wheel motor (S113 to S114) of generating a brake pressure by driving the clutch and the engine when the hydraulic braking pressure reaches a required time during the execution of the regenerative braking as in the step (b) (d) After the step (c), the regenerative braking of the front wheel motor is continuously checked by using only the rear wheel motor, and if the regenerative braking of the front wheel motor is possible, the front wheel motor And a step (S115 ~ S120), (e) steps (S121 ~ S122) for stopping the regenerative braking of the front wheel / rear wheel when the motor (d) after the step, the hydraulic brake is operated to perform a regenerative braking.

The method of controlling the costing and regenerative braking of the four-wheel drive hybrid vehicle according to the present invention will now be described in detail.

First, in step S101, the hybrid controller 106 detects the accelerator pedal value in real time in the vehicle, confirms whether the accelerator pedal value is "0" in step S102, and if the accelerator pedal value is "0" And measures the distance to the forward object through the distance measuring unit 107. The distance measuring unit 107 preferably uses a distance sensor, a camera, or the like.

If it is determined in step S104 that the distance to the forward object is less than or equal to a preset distance for starting coasting as shown in FIG. 2, and if the distance from the forward object is less than the predetermined distance, The routine goes to S105 to turn off the engine and the clutch. Then, the routine goes to step S106 and enters a running zone in which the running of the batting is performed.

Next, in step S107, when the distance from the preceding object to the forward object during the course of the course is within the distance required to start the regenerative braking, the process goes to step S108 to check the distance between the current vehicle speed and the forward object. Here, the distance to start regenerative braking means the regenerative braking starting point as shown in Fig. 2, and it is preferable to set it in advance by experiment.

Next, the maximum regenerative braking power is calculated in step S109, the available battery power is calculated in step S110, the real-time optimal regenerative braking power is calculated on the basis of the maximum regenerative braking power and the battery acceptable power in step S111, In S112, only the rear wheel motor is controlled based on the calculated optimum regenerative braking power to start regenerative braking.

Here, the calculation of the maximum regenerative braking power, the power of the battery, and the regenerative braking power in real time can be performed in accordance with Patent Document 1 described in the prior art documents and Korean Patent Registration No. 10-1712285 (issued on March 31, 2013) The regenerative braking control method of the hybrid vehicle or the electric vehicle).

Next, in step S113, regenerative braking is continuously performed using only the rear wheel motor based on the interval-by-interval running and regenerative braking control timing as shown in FIG. 2, and when the hydraulic braking pressure reaches the required point of time, The clutch and the engine are driven to generate the brake pressure.

Next, in step S115, the maximum current regenerative braking power is calculated in step S116, the available battery power is calculated in step S117, and the maximum regenerative braking power and the maximum regenerative braking power are calculated in step S118. Time optimal regenerative braking power based on the battery-receivable power. Here, it is preferable that each of the power calculations is calculated by adopting the calculation method disclosed in the above-mentioned < Patent Document 1 > and < Prior Art >

Next, the process proceeds to step S119, and the possibility of regenerative braking of the front wheel motor is confirmed while continuously performing regenerative braking using only the rear wheel motor. If it is determined that the regenerative braking of the front wheel motor is possible, the process proceeds to step S120 to start regenerative braking using the front wheel motor.

Next, in step S121, when the point at which the negative pressure of the engine is to be generated for the engine hydraulic brake operation is reached as shown in Fig. 2, the clutch and the engine are turned on to generate the brake pressure. The hydraulic brake is operated by using the brake pressure thus generated.

Finally, when the hydraulic brake is operated as described above in step S122, the regenerative braking of the front wheel / rear wheel motor is stopped. At this time, the vehicle also stops.

As described above, the present invention can automatically turn off the engine and the clutch of the vehicle using a signal lamp, distance information with an object such as a person, vehicle speed information, etc., to the front surface of the vehicle, .

When the distance from the preceding object enters the point where the regenerative braking should start, the regenerative braking is started with the rear wheel motor only by using the rear wheel motor control inverter during the course of the course. Next, if the front wheel motor regenerative braking is possible, the regenerative braking is controlled in such a manner as to start regenerative braking of the front wheel motor mounted on the engine belt on the front wheel, thereby maximizing the regenerative braking with the rear wheel motor, Fuel efficiency will be improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It is obvious to those who have.

The present invention is applied to a technique for controlling a costing and a regenerative braking by using a rear wheel motor and a front wheel motor in a four-wheel drive mild hybrid vehicle.

103: Brake device 104: Front wheel motor
105: Rear wheel motor 106: Hybrid controller
107: Distance measuring unit 108, 110: First and second inverters
109: Battery management system 111: Power converter
112: 12V battery

Claims (4)

A method of controlling a running and regenerative braking in a four-wheel drive hybrid vehicle that performs regenerative braking using a front wheel motor and a rear wheel motor,
(a) detecting a distance to a forward object when the accelerator pedal is not operated during traveling, and entering a course section if the distance from the forward object is less than a predetermined distance;
(b) performing regenerative braking using only the rear wheel motor if the distance from the forward object during the course of the course is a distance at which regenerative braking should be started;
(c) generating a brake pressure by driving the clutch and the engine when a hydraulic brake pressure reaches a required time during the execution of the regenerative braking as in the step (b);
(d) performing regenerative braking using the front wheel motor when the regenerative braking of the front wheel motor is possible by confirming the possibility of regenerative braking of the front wheel motor while continuously performing regenerative braking only using the rear wheel motor only after the step (c); And
(e) stopping the regenerative braking of the front wheel / rear wheel motor when the hydraulic brakes are operated after the step (d).
The method of claim 1, wherein the step (a) includes: (a1) checking whether the accelerator pedal value is "0" during driving the vehicle; (a2) If the accelerator pedal value is "0 &quot;, the distance to the forward object is measured, and if the measured distance from the forward object is less than a predetermined distance, the engine and clutch are turned off, And a control unit for controlling the operation of the four-wheel drive hybrid vehicle.
The method of claim 1, wherein the step (b) comprises the steps of: (b1) confirming a distance between a current vehicle speed and a forward object if the distance from the forward object is a distance at which regenerative braking should be started; (b2) calculating a maximum regenerative braking power; (b3) calculating power acceptable for the battery; (b4) calculating a real time optimal regenerative braking power based on the maximum regenerative braking power and the battery accommodatable power; (b5) controlling the rear wheel motor based on the calculated optimum regenerative braking power to start regenerative braking.
The method of claim 1, wherein the step (d) comprises the steps of: (d1) confirming the distance between the current vehicle speed and the forward object while continuously performing regenerative braking using only the rear wheel motor; (d2) calculating a maximum regenerative braking power; (d3) calculating a battery acceptable power; (d4) calculating a real time optimal regenerative braking power based on the maximum regenerative braking power and the battery accommodatable power.

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