KR20190003074A - Hybrid vehicle and method of changing operation mode for the same - Google Patents

Abstract

The present invention relates to a hybrid vehicle and a driving mode control method for the same and, more specifically, to a hybrid vehicle and a driving mode control method for the same, wherein a driving mode related to changes in a charging amount of a battery can be changed in consideration of a charging pattern of a user. To this end, according to an embodiment of the present invention, the driving mode control method comprises the following steps of: performing first-mode driving after charging; and performing second-mode driving when a battery SOC value is less than a predetermined mode conversion reference value. Moreover, the step of performing second-mode driving can comprise the following steps of: determining a charging tendency of a driver; and controlling a battery charging allowance range during the second-mode driving in accordance with the determined charging tendency.

Description

HYBRID VEHICLE AND METHOD OF CHANGING OPERATION MODE FOR THE SAME [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid vehicle and a traveling mode control method therefor, and more particularly, to a hybrid vehicle and a control method thereof capable of performing a traveling mode change related to a variation in a charged amount of a battery in consideration of a charging pattern of a user.

Hybrid Electric Vehicle (HEV) is a vehicle that uses two power sources in common. The two power sources are mainly engine and electric motor. Such a hybrid vehicle is superior to a vehicle equipped with an internal combustion engine only in terms of fuel economy and power performance, and is also advantageous in reducing exhaust gas.

These hybrid cars can operate in two modes depending on which power train they are driving. One of them is an electric vehicle (EV) mode in which an electric motor only runs, and the other is a hybrid electric vehicle (HEV) mode in which an electric motor and an engine are operated together to obtain power. The hybrid vehicle performs switching between the two modes according to the driving conditions. The energy efficiency characteristics of such a hybrid power train will be described with reference to Fig.

1 is a view for explaining power train energy efficiency characteristics of a general hybrid vehicle.

In FIG. 1, the horizontal axis represents the power train output (POWER) and the vertical axis represents the system efficiency of the power train.

Referring to FIG. 1, the EV mode driving using the electric motor is effective in the low output section, but the HEV mode driving is more effective after the point A where the efficiency of the EV mode intersects with the efficiency of the HEV mode. Also, the electric motor generally reaches the maximum output point C first than the engine.

2 is a diagram for explaining load leveling in the HEV mode in a general hybrid vehicle.

Referring to FIG. 2, in the HEV mode, the electric motor and the engine are driven together. In this case, the operating point (for example, point (B) in FIG. Accordingly, when power higher than the optimum engine efficiency point is required, the output of the electric motor is added so that the electric motor operates in the discharge mode, and vice versa, the electric motor performs charging with the surplus output of the engine.

Therefore, in the HEV mode, the load energy can be stored in the battery, and the load leveling can be performed to improve the overall driving efficiency when necessary. Such load leveling increases as the capacity of a battery, which serves as a buffer for storing energy, increases.

In addition to the classification of the traveling mode according to the power system described above, in particular, in the case of a plug-in hybrid vehicle (PHEV), a discharge (CD: Charge Depletion) mode and a charge holding CS: Charge Sustaining) mode. Generally, in the CD mode, the electric motor is driven by the electric power of the battery. In the CS mode, the power of the engine is mainly used so that the battery SOC is not lowered. In the mode division, the point (A) in FIG. 1 can be a reference for starting the engine in the CS mode, and the point (B) at which the efficiency of the HEV mode becomes the maximum is the reference .

In the case of a general PHEV, the vehicle travels in the CD mode regardless of the driving conditions such as the driving load, the chargeability, and the distance to the destination, and then switches to the CS mode according to the exhaustion of the SOC. This will be described with reference to FIG.

FIGS. 3 and 4 show an example of a mode in which SOC-based mode switching is performed in a general plug-in hybrid vehicle.

3, the abscissa represents the distance, the ordinate axis of the upper graph represents the battery charge state (SOC) of the PHEV, and the ordinate axis of the lower graph represents the running load.

Referring to the lower graph of FIG. 3, a route having a relatively low running load is shown in the order of highway, national highway, and urban highway in the order of city, highway, and highway between the place of departure and destination. When driving this route, the general PHEV starts the CD mode at the start without considering the fluctuation of the running load, and performs switching to the CS mode when the SOC falls below the preset reference.

However, the CD mode exhibits relatively favorable efficiency at low / low load driving, and the CS mode has a relatively favorable efficiency at high / high load driving. Therefore, when mode switching is performed based only on the SOC value as described above, energy efficiency characteristics of the traveling load and the hybrid power train are not considered, so that the efficiency may be significantly reduced depending on the route.

In addition, as shown in FIG. 4, when the battery SOC travels to the SOC that is the reference for switching to the CS mode during the CD mode travel, the mode is switched to the CS mode, so the travel continues in the HEV mode in the vicinity of the SOC as the switching reference. Therefore, unless the plug-in charging using external power is performed, the actual battery use range is narrowly limited in the CS mode, and the load leveling efficiency of the HEV traveling is inevitably lowered.

Hereinafter, with reference to FIG. 5 and FIG. 6, the problems that may occur during continuous driving of the CS mode in the plug-in hybrid vehicle will be described.

FIGS. 5 and 6 are diagrams for explaining a problem in the CS mode continuous running in a general plug-in hybrid vehicle.

Referring to FIG. 5, it can be seen that the battery efficiency shows the maximum efficiency near the midpoint of the maximum SOC, and the efficiency decreases as the efficiency point gets farther from the maximum efficiency point. However, when the CS mode is continuously operated after switching from the CD mode to the CS mode based on the SOC, the SOC is kept low, which is not preferable from the viewpoint of the battery efficiency.

Conversely, as shown in FIG. 6, when the battery usage is arbitrarily increased in the CS section without considering the charging pattern of the driver, the amount of power that can be charged through the external power is limited. That is, if the battery is charged using the fuel without predicting the charging time using the external power, there is a problem that the charging using the fuel consumption is relatively unnecessary.

The present invention provides a method for performing mode switching control more efficiently and a hybrid vehicle for performing the same.

Particularly, the present invention is to provide a method for variably setting an optimum mode switching reference and a vehicle for performing the same.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, unless further departing from the spirit and scope of the invention as defined by the appended claims. It will be possible.

According to an aspect of the present invention, there is provided a method of controlling a mode switching of a hybrid vehicle, the method comprising: performing a first mode travel after charging; And performing a second mode travel when the battery SOC value is less than a predetermined mode switching reference value, wherein the step of performing the second mode travel includes determining a charging tendency of the driver; And controlling the battery charging allowable range during the second mode running according to the determined charging tendency.

According to another aspect of the present invention, there is provided a hybrid vehicle including: an engine controller for controlling an engine; A motor controller for controlling an electric motor that receives electric power from the battery or charges the battery using the power of the engine; And a hybrid controller for controlling the engine controller and the motor controller, wherein the hybrid controller causes the first mode travel to be performed after the battery is charged using external power, and the SOC value of the battery is set to a predetermined mode switching reference value The control of the second mode travel determines the charge tendency of the driver and controls the battery charge allowable range during the second mode travel according to the determined charge tendency .

The hybrid vehicle according to at least one embodiment of the present invention configured as described above can perform mode switching control more efficiently.

Particularly, since the range of the load leveling is determined in consideration of the charging pattern of the user, the SOC section with higher battery efficiency can be used for the load leveling and the fuel economy can be improved.

The effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description will be.

1 is a view for explaining power train energy efficiency characteristics of a general hybrid vehicle.
2 is a diagram for explaining load leveling in the HEV mode in a general hybrid vehicle.
FIGS. 3 and 4 show an example of a mode in which SOC-based mode switching is performed in a general plug-in hybrid vehicle.
FIGS. 5 and 6 are diagrams for explaining a problem in the CS mode continuous running in a general plug-in hybrid vehicle.
7 shows an example of a power train structure of a hybrid vehicle to which embodiments of the present invention can be applied.
8 is a block diagram showing an example of a control system of a hybrid vehicle to which embodiments of the present invention can be applied.
FIG. 9 shows an example of a method for determining a charging tendency of a user according to an embodiment of the present invention.
FIG. 10 shows an example of a mode in which the load leveling range is changed according to an embodiment of the present invention.
FIG. 11 shows an example of a SOC variation form when the load leveling range is controlled according to driver tendency judgment according to an embodiment of the present invention.
12 is a flowchart illustrating an example of a load leveling change control process based on charge pattern determination according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise. In addition, parts denoted by the same reference numerals throughout the specification denote the same components.

Before describing a mode switching method according to an embodiment of the present invention, a hybrid vehicle structure to which embodiments of the present invention can be applied will be described first with reference to FIG.

7 shows an example of a power train structure of a hybrid vehicle to which embodiments of the present invention can be applied.

7, an electric motor (or a driving motor) 140 and an engine clutch (EC) 130 are mounted between the internal combustion engine (ICE) 110 and the transmission 150, ) ≪ / RTI > of a hybrid vehicle employing a hybrid system.

In such a vehicle, in general, when the driver steps on the accelerator, the motor 140 is first driven using the power of the battery in the state where the engine clutch 130 is opened, and the power of the motor is transmitted to the transmission 150 and the decelerator 150. [ (FD) drive (Final Drive, 160). When the vehicle is gradually accelerated and a gradually larger driving force is required, the auxiliary motor (or the startup power generation motor) 120 is operated to drive the engine 110. [

Accordingly, when the rotational speeds of the engine 110 and the motor 140 become equal to each other, the engine clutch 130 is engaged and the engine 110 and the motor 140 together or the engine 110 drives the vehicle , HEV mode transition in EV mode). The engine clutch 130 is opened and the engine 110 is stopped (i.e., the EV mode transition is performed in the HEV mode) if the predetermined engine off condition such as the vehicle deceleration is satisfied. Further, in the hybrid vehicle, the driving force of the wheel during braking can be converted into electric energy to charge the battery, which is called braking energy regeneration or regenerative braking.

Since the start-up power generation motor 120 acts as a start motor when the engine is started, and operates as a generator when the start energy is recovered or after the rotation energy of the engine is recovered at the time of start-off, "Hybrid Start Generator, "and may also be referred to as" auxiliary motor "in some cases.

The correlation between the controllers in the vehicle to which the above-described power train is applied is shown in Fig.

8 is a block diagram showing an example of a control system of a hybrid vehicle to which embodiments of the present invention can be applied.

8, in the hybrid vehicle to which the embodiments of the present invention can be applied, the internal combustion engine 110 is controlled by the engine controller 210, the start-up power generation motor 120 and the electric motor 140 are controlled by the motor controller (MCU) : The motor control unit 220, and the engine clutch 130 can be controlled by the clutch controller 230, respectively. Here, the engine controller 210 may be an engine management system (EMS). Also, the transmission 150 is controlled by the transmission controller 250. In some cases, a controller for the start-up power generation motor 120 and a controller for each of the electric motors 140 may be separately provided.

Each controller is connected to a hybrid controller (HCU) 240 that controls the entire mode switching process as its upper controller, and is controlled by the hybrid controller 240 to change the running mode, Information and / or information necessary for engine stop control to the engine 240, or to perform an operation according to the control signal.

More specifically, the hybrid controller 240 determines whether to perform a mode change according to the driving state of the vehicle. For example, the hybrid controller determines the time when the engine clutch 130 is released, and performs control of hydraulic pressure (in case of wet EC) or control of torque capacity (in case of dry EC) upon release. Also, the hybrid controller 240 can determine the state of the EC (Lock-up, Slip, Open, etc.) and control the fuel injection stop time of the engine 110. Further, the hybrid controller may control the engine rotational energy recovery by transmitting a torque command to the motor controller 220 for controlling the torque of the startup power generation motor 120 for engine stop control. In addition, the hybrid controller 240 can control the sub-controller for determining and switching the mode change condition at the time of switching control between the EV-HEV and the CS-CD mode.

Of course, it is apparent to those skilled in the art that the control period connection relationship and the function / division of each controller described above are illustrative and not limited to the names. For example, the hybrid controller 240 may be implemented so that the corresponding function is provided to be replaced in any one of the other controllers except for the hybrid controller 240, and the corresponding function may be distributed in two or more of the other controllers.

Hereinafter, a more efficient mode switching control method according to an embodiment of the present invention will be described based on the above vehicle structure.

As described above, when switching between the CD-CS modes based on SOC, the actual battery use range is limited in the CS mode, and even when the battery use range is uniformly increased, the charge range using external power may be limited .

Therefore, in one embodiment of the present invention, it is proposed that the range of load leveling is determined in consideration of the charging pattern or the charging tendency of the user, so that the SOC section with variable battery efficiency can be used for load leveling.

To do this, the charging tendency of the user should be determined first. This will be described with reference to FIG.

FIG. 9 shows an example of a method for determining a charging tendency of a user according to an embodiment of the present invention. In FIG. 9, it is assumed that the determination of the charge propensity is performed in a state where external charging is not performed.

Referring to FIG. 9, the charging tendency judgment can be largely performed by detecting vehicle driving information and SOC fluctuation.

The vehicle driving information may again include at least one of navigation information, driving cycle, time, and distance information. Here, the navigation information may be whether or not there is a facility (for example, household charger, public charging station, etc.) that can be charged within a certain mileage. Also, the driving cycle may be the distance from the external charge to the start-off. In addition, the time and distance information may be at least one of a total travel distance after the external charge, an average value of the travel distance between the charge and the charge extracted from the existing charge history, a predicted charge estimation time or a predicted distance using the dispersion, .

The detection of the SOC fluctuation can be performed through at least one of the measurement of the charge information according to the external charge and the measurement of the actual SOC value.

It can be judged whether or not the driver has a long-term non-charging tendency not to charge for a long time through the above-described information.

More specifically, it is possible to perform the following functions: 1) when the driving distance after the external charging is ≥ C1 2) when the driving cycle after the external charging is ≥ C2 3) when it is set directly through the user input device 4) , Or 5) the remaining distance to the next charge> = C3, that is, (estimated charging time or distance) - actual traveling distance ≥ C3. Here, C1, C2, and C3 are predetermined distance values, and the respective values may be equal to or different from each other.

FIG. 10 shows an example of a mode in which the load leveling range is changed according to an embodiment of the present invention.

As a result of the charging tendency judgment shown in FIG. 9, when the driver is judged to have the long-term non-charging tendency, the load leveling range is increased to be larger than the default value (i.e., And if not, the load leveling range can be maintained at the default value.

The SOC fluctuation when the load leveling range is expanded beyond the default value as the driver is determined to have a long-term non-charge tendency will be described with reference to FIG.

FIG. 11 shows an example of a SOC variation form when the load leveling range is controlled according to driver tendency judgment according to an embodiment of the present invention.

11, after the battery is charged through external power, the average travel distance from the charge to the next charge corresponds to the entire horizontal axis, and the vertical axis represents the SOC.

Referring to FIG. 11, since the SOC is high immediately after charging, the CD mode travel is performed, and the SOC is changed to the CS mode when the SOC reaches the mode switching reference. However, if the load leveling interval is enlarged according to the determination of the charging tendency of the driver, the SOC can be increased by performing aggressive charging with the surplus power of the engine in the section where the engine efficiency is good in the CS mode during the enlarged section. The load leveling enlargement period ends when the value obtained by subtracting the actual running distance from the average running distance between the charging and the charging is less than C3, and the load leveling range is restored to the default value by the distance corresponding to C3.

When the load leveling range is restored to the default value, the battery SOC increased in the load leveling enlargement section is lowered while traveling at a distance corresponding to C3. Therefore, when the next charge is performed, the external power can be fully utilized due to the low SOC.

A load leveling change control process based on charge pattern determination according to an embodiment of the present invention will be described with reference to FIG.

12 is a flowchart illustrating an example of a load leveling change control process based on charge pattern determination according to an embodiment of the present invention. Each determination process of FIG. 12 can be performed in the hybrid controller, but it is not limited to such a determination subject.

Referring to FIG. 12, it can be determined whether the battery SOC is equal to or higher than the switching criterion for the CD-> CS mode (S1210).

As a result of the determination, if it is equal to or higher than the switching reference, the CD mode driving is performed (S1220).

Conversely, if the switching reference is less than the switching reference, the charging pattern of the driver can be determined (S1230). As a result of the charge pattern determination, if the long-term non-charge tendency is satisfied, the SOC charge limit value may be set to a value (A2) higher than the default value (A1) in order to expand the load leveling range (S1240A). Otherwise, if the long-term non-charge tendency is not satisfied, the SOC charge limit value may be set to the default value A1 (S1240B).

Of course, the value A2 set in the step S1240A may be reset to the value A1 if the remaining distance to the point where the next charging is expected is less than C3, as described above. The A2 value preferably includes at least a part of the maximum efficiency period of the battery mounted on the vehicle.

The following effects can be expected through the load leveling change control based on the charge pattern determination according to the present embodiment described above.

First, since the SOC section having the maximum efficiency of the battery can be used due to the expansion of the load leveling range, the fuel efficiency improvement effect can be expected.

In addition, drivers who rarely charge via external power may complain that they are constantly seeing a notice of low SOC on the cluster, which can increase the SOC above the warning value by expanding the range of load leveling Such driver complaints can be resolved.

The present invention described above can be embodied as computer-readable codes on a medium on which a program is recorded. The computer readable medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of the computer readable medium include a hard disk drive (HDD), a solid state disk (SSD), a silicon disk drive (SDD), a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, .

Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

Claims (17)

A mode switching control method for a hybrid vehicle,
Performing a first mode travel after charging; And
And performing a second mode travel when the battery SOC value becomes less than a predetermined mode switching reference value,
The step of performing the second mode travel may include:
Determining a charging tendency of the driver; And
And controlling the battery charging permissible range during the second mode traveling according to the determined charging tendency. The method according to claim 1,
Wherein the determining step comprises:
Wherein the control is performed using the vehicle operation information and the SOC change detection information. 3. The method of claim 2,
The vehicle-
Navigation information, driving cycle information, mileage information, and driving time information,
The change detection information of the SOC includes:
And the charge related information using the measured value of the SOC and the external power. 3. The method of claim 2,
Wherein the controlling comprises:
Setting the battery charge tolerance range to a second value different from a first value that is a default value when the determined charge tendency is a long-term non-charge tendency; or
And maintaining the battery charging allowable range at the first value when the determined charging tendency does not correspond to the long-term non-charging tendency. 5. The method of claim 4,
Wherein the controlling comprises:
When the battery charging allowable range is set to the second value and the value obtained by subtracting the distance traveled after charging from the average traveling distance between charges is less than the first threshold distance, Further comprising the step of controlling the mode switching of the hybrid vehicle. 5. The method of claim 4,
Wherein the second value is greater than the first value. The method according to claim 1,
Wherein the determining step comprises:
When the driving distance after charging is equal to or greater than the first threshold distance and the driving cycle after charging is equal to or greater than the second threshold distance and the long term non-charging tendency is directly set through the user input device, And the remaining distance from the charging to the next charge is equal to or greater than the third critical distance, determining the long-term non-charging tendency. The method according to claim 1,
Wherein the first mode includes a CD (Charge Depleting) mode and the second mode includes a Charge Sustaining (CS) mode. A computer-readable recording medium on which a program for executing a mode switching control method of a hybrid vehicle according to any one of claims 1 to 8 is recorded. In a hybrid vehicle,
An engine controller for controlling the engine;
A motor controller for controlling an electric motor that receives electric power from the battery or charges the battery using the power of the engine; And
And a hybrid controller for controlling the engine controller and the motor controller,
The hybrid controller includes:
Wherein the first mode travel is performed after the battery is charged using external power and the second mode travel is performed when the SOC value of the battery becomes less than a preset mode switch reference value,
Wherein the control of the second mode travel comprises:
Wherein the controller is configured to determine a charging tendency of the driver and to control the battery charging permissible range during the second mode traveling according to the determined charging tendency. 11. The method of claim 10,
The hybrid controller includes:
Wherein the controller determines the charging tendency by using the vehicle driving information and the variation detection information of the SOC. 12. The method of claim 11,
The vehicle-
Navigation information, driving cycle information, mileage information, and driving time information,
The change detection information of the SOC includes:
A measured value of the SOC, and charging related information using external power. 12. The method of claim 11,
The hybrid controller includes:
And setting the battery charging permission range to a second value different from a first value which is a default value when the determined charging tendency is a long-term non-charging tendency, and when the determined charging tendency does not correspond to a long- And maintains the range at the first value. 14. The method of claim 13,
The hybrid controller includes:
When the battery charging allowable range is set to the second value and the value obtained by subtracting the distance traveled after charging from the average traveling distance between charges is less than the first threshold distance, , A hybrid car. 14. The method of claim 13,
Wherein the second value is greater than the first value. 11. The method of claim 10,
The hybrid controller includes:
When the driving distance after charging is equal to or greater than the first threshold distance and the driving cycle after charging is equal to or greater than the second threshold distance and the long term non-charging tendency is directly set through the user input device, , And when the remaining distance to the next charge is equal to or greater than the third critical distance, the hybrid vehicle judges the long-term non-charging tendency. 11. The method of claim 10,
Wherein the first mode includes a CD (Charge Depleting) mode, and the second mode includes a CS (Charge Sustaining) mode.

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