KR102756621B1 - Hybrid vehicle and method of driving mode control for the same - Google Patents

Abstract

The present invention relates to a hybrid vehicle capable of switching driving modes in consideration of a driver's tendencies, and a mode control method therefor. The control method of a hybrid vehicle according to one embodiment of the present invention may include the steps of: determining a target ratio range between a first driving mode using only a driving motor and a second driving mode using at least an engine, based on a current battery state (SOC: State Of Charge); predicting a driving mode ratio based on accumulated and collected driver's accelerator pedal operation tendencies information and a currently set mode switching criterion; determining whether the predicted driving mode ratio satisfies the target ratio range; and adjusting the mode switching criterion based on the accumulated and collected driver's accelerator pedal operation tendencies information so as to satisfy the target ratio range, if the determined result shows that the predicted driving mode ratio does not satisfy the target ratio range.

Description

HYBRID VEHICLE AND METHOD OF DRIVING MODE CONTROL FOR THE SAME

The present invention relates to a hybrid vehicle capable of switching driving modes in consideration of a driver's tendencies and a mode control method therefor.

Hybrid vehicles (HEV: Hybrid Electric Vehicle) are generally vehicles that use two power sources together, and the two power sources are mainly an engine and an electric motor. These hybrid vehicles are not only superior in fuel efficiency and power performance compared to vehicles equipped with only internal combustion engines, but are also advantageous in reducing exhaust gas, so they are being developed a lot recently.

These hybrid vehicles can operate in two driving modes, depending on the powertrain. One of them is an electric vehicle (EV) mode that runs solely on electric motors, and the other is a hybrid electric vehicle (HEV) mode that runs both the electric motor and the engine. Hybrid vehicles switch between the two modes depending on driving conditions.

Such switching between driving modes is usually performed for the purpose of maximizing fuel efficiency or driving efficiency, depending on the efficiency characteristics of the powertrain. For example, switching between driving modes is usually determined as EV mode if the required torque or power according to the driver's accelerator pedal operation amount is lower than the mode switching standard set based on system efficiency, and HEV mode if it is higher than the mode switching standard. Of course, the state of charge (SOC: State Of Charge) of the battery installed in the hybrid vehicle can also be considered, but it is limited to switching to HEV mode when the SOC falls below a certain standard. Ultimately, in a situation where the SOC is higher than a certain standard, whether or not to switch modes is dependent on the driver's required power, which changes from moment to moment, so it is difficult for the SOC to actually affect the switching of driving modes. The problem in this case is explained with reference to Fig. 1.

Figure 1 is a drawing for explaining an example of the relationship between the driver's demand power distribution and the mode switching criteria. In Figure 1, the horizontal axis represents the demand power according to the driver's accelerator pedal operation amount, and the vertical axis represents the occurrence frequency of the demand power.

Referring to Fig. 1, in a situation where the mode switching criterion based on system efficiency is set to the required power, if the driver's accelerator pedal operation tendency is biased toward the right side of the mode switching criterion, that is, the high power area (a2), as shown in the graph, the proportion of HEV mode driving increases. Accordingly, even if the SOC is sufficient, the probability of engine start-up is high, and if the SOC is maintained high, there is a concern that the system efficiency may drop significantly because even restrictions on regenerative braking may occur.

Of course, recent hybrid cars are introducing technology that learns the driver's tendencies in order to reflect the driver's accelerator pedal operation tendencies in changing driving modes.

However, this also only matches the driver's tendencies to one of several preset categories, and is not helpful for sophisticated SOC management.

The present invention provides a hybrid vehicle capable of more efficient driving mode switching control and a control method thereof.

In particular, the present invention provides a hybrid vehicle capable of controlling driving mode switching based on the current battery status and driver's tendencies, and a control method thereof.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

In order to solve the above technical problem, a control method of a hybrid vehicle according to an embodiment of the present invention may include the steps of: determining a target ratio range between a first driving mode using only a driving motor and a second driving mode using at least an engine, based on a current battery state (SOC: State Of Charge); predicting a driving mode ratio based on accumulated and collected driver's accelerator pedal operation tendency information and a currently set mode switching criterion; determining whether the predicted driving mode ratio satisfies the target ratio range; and adjusting the mode switching criterion based on the accumulated and collected driver's accelerator pedal operation tendency information so as to satisfy the target ratio range, if the determined result shows that the predicted driving mode ratio does not satisfy the target ratio range.

In addition, a hybrid vehicle according to one embodiment of the present invention may include an accelerator pedal sensor that detects an accelerator pedal operation amount of a driver; and a hybrid controller that determines a target ratio range between a first driving mode using only a driving motor and a second driving mode using at least an engine based on a current battery state (SOC: State Of Charge), predicts a driving mode ratio based on the driver's accelerator pedal operation tendency information accumulated and collected through the accelerator pedal sensor and a currently set mode switching criterion, and adjusts the mode switching criterion based on the accumulated driver's accelerator pedal operation tendency information so as to satisfy the target ratio range when the predicted driving mode ratio does not satisfy the target ratio range.

A hybrid vehicle according to at least one embodiment of the present invention configured as described above is capable of more efficient driving mode switching.

In particular, according to embodiments of the present invention, the mode switching criteria can be adjusted based on the driver's tendency to operate the accelerator pedal so as to satisfy a desirable ratio between driving modes for the current battery status, which is advantageous for SOC balancing and improved fuel efficiency.

The effects obtainable from the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

Figure 1 is a drawing to explain an example of the relationship between the driver's required power distribution and the mode switching criteria.
FIG. 2 shows an example of a power train structure of a parallel hybrid vehicle that can be applied to embodiments of the present invention.
FIG. 3 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. 4 illustrates an example of a change in the form of a driver's demand power distribution and a mode switching criterion based on SOC according to one embodiment of the present invention.
FIG. 5 is a flowchart showing an example of a mode switching criterion control process according to one embodiment of the present invention.
FIG. 6 is a drawing for explaining a mode ratio map form and a mode switching criterion adjustment form that can be applied to mode switching criterion control according to one embodiment of the present invention.
FIG. 7 shows an example of a form of outputting that a change in mode switching criteria is performed according to one embodiment of the present invention.

Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts that are not related to the description are omitted, and similar parts are assigned similar drawing reference numerals throughout the specification.

Throughout the specification, whenever a part is said to "include" a certain component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated. Furthermore, parts designated by the same reference numerals throughout the specification refer to the same components.

Before describing a hybrid vehicle and a driving mode switching control method thereof according to an embodiment of the present invention, the powertrain configuration and control system of the hybrid vehicle applicable to the embodiments will first be described.

First, the hybrid vehicle structure is described with reference to Fig. 2. Fig. 1 shows an example of a power train structure of a parallel hybrid vehicle that can be applied to embodiments of the present invention.

Referring to FIG. 2, a power train of a hybrid vehicle is illustrated that employs a parallel type hybrid system in which an electric motor (or drive motor, 140) and an engine clutch (EC: Engine Clutch, 130) are mounted between an internal combustion engine (ICE, 110) and a transmission (150).

In these vehicles, when the driver steps on the accelerator pedal after starting, the engine clutch (130) is opened and the motor (140) is driven first using the power of the battery, and the power of the motor moves the wheels through the transmission (150) and the final drive (FD: Final Drive, 160) (i.e., EV mode). When the vehicle gradually accelerates and a greater driving force is required, the auxiliary motor (or, starter-generator motor, 120) may be operated to drive the engine (110).

Accordingly, when the rotation speeds of the engine (110) and the motor (140) become the same, the engine clutch (130) is engaged so that the engine (110) and the motor (140) drive the vehicle together, or the engine (110) drives the vehicle (i.e., transition from EV mode to HEV mode). When a preset engine-off condition, such as when the vehicle decelerates, is satisfied, the engine clutch (130) is opened and the engine (110) is stopped (i.e., transition from HEV mode to EV mode). In addition, in a hybrid vehicle, the driving force of the wheels can be converted into electric energy during braking to charge the battery, which is called braking energy regeneration, or regenerative braking.

The starter generator motor (120) functions as a starter motor when the engine is started, and operates as a generator when recovering the rotational energy of the engine after the engine is started or when the engine is turned off. Therefore, it can be called a “hybrid starter generator (HSG)” and, in some cases, it can also be called an “auxiliary motor.”

The interrelationships between controllers in a vehicle to which this power train is applied are illustrated in Fig. 3.

FIG. 3 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.

Referring to FIG. 3, in a hybrid vehicle to which embodiments of the present invention can be applied, an internal combustion engine (110) is controlled by an engine controller (210), a starter/generator motor (120) and an electric motor (140) can have their torque controlled by a motor controller (MCU: Motor Control Unit, 220), and an engine clutch (130) can be controlled by a clutch controller (230). Here, the engine controller (210) is also called an engine control system (EMS: Engine Management System). In addition, a transmission (150) is controlled by a transmission controller (250). In some cases, a controller for each of the starter/generator motor (120) and the electric motor (140) may be provided separately.

Each controller is connected to a hybrid controller (HCU: Hybrid Controller Unit, 240) that controls the entire mode switching process as its upper controller, and can provide the hybrid controller (240) with information necessary for changing driving modes, controlling engine clutch during gear shifting, and/or controlling engine stop, or perform operations according to control signals.

More specifically, the hybrid controller (240) determines whether to perform a mode switch according to the driving state of the vehicle. For example, the hybrid controller determines the release (Open) timing of the engine clutch (130), and performs hydraulic pressure (in the case of a wet EC) control or torque capacity control (in the case of a dry EC) at the time of release. In addition, the hybrid controller (240) can determine the state (Lock-up, Slip, Open, etc.) of the engine clutch (130) and control the fuel injection stop timing of the engine (110). In addition, the hybrid controller can control engine rotation energy recovery by transmitting a torque command for controlling the torque of the starter-generator motor (120) for engine stop control to the motor controller (220). In addition, the hybrid controller (240) can control a lower controller for judging and switching the mode switch condition during the driving mode switch control.

Of course, it is obvious to those skilled in the art that the above-described control period connection relationship and the functions/divisions of each controller are exemplary and are not limited to the names. For example, the hybrid controller (240) may be implemented so that the corresponding function is provided by replacing it in any one of the other controllers, or the corresponding function may be provided by distributing it in two or more of the other controllers.

The configurations of Figures 2 and 3 described above are only examples of hybrid vehicle configurations, and it will be apparent to those skilled in the art that hybrid vehicles applicable to the embodiments are not limited to these structures.

In one embodiment of the present invention, it is proposed to control a mode switching criterion so that a desirable driving mode ratio for the current SOC can be achieved based on the accumulated driver's accelerator pedal operation tendency.

The concept of mode switching criterion control according to one embodiment of the present invention is explained with reference to FIG. 4. FIG. 4 shows an example of a change form of a mode switching criterion based on a driver's demand power distribution and SOC according to one embodiment of the present invention. In FIG. 4, the horizontal axis represents the demand power according to the driver's accelerator pedal operation amount, and the vertical axis represents the occurrence frequency of the accumulated collected demand power.

In the graph shown in Fig. 4, the driver's demand power is concentrated in a relatively high power range. In this situation, if the default mode switching criterion (410) is set, EV mode driving will be performed in the left area (a1) of the mode switching criterion (410) in the graph, and HEV mode driving will be performed in the right area (a2) of it (410). In Fig. 4, since a2 is relatively large with the default mode switching criterion (410) as the center, the proportion of the HEV mode during driving will be relatively higher than that of the EV mode.

This ratio between driving modes may be desirable in situations where the SOC is low, but in situations where it is acceptable to consume SOC for efficient driving, such as when the SOC is high, or where it is desirable to lower the SOC, it is desirable to set the default mode switching criterion (410) to a higher value (420). For example, in a situation where the driving mode control is ideally scheduled so that the target ratio of the EV mode and the HEV mode during driving is 4:6 considering the current SOC, if the default mode switching criterion (410) is applied to the driver's accelerator pedal operation tendency, it is predicted that it will be difficult to satisfy the target ratio because 'a1:a2 = 3:7', and in this embodiment, the mode switching criterion can be raised so that the target ratio can be satisfied (for example, so that 'a1:a2 = 4:6'). The operation process of the hybrid controller (240) for this purpose will be described with reference to FIGS. 5 and 6 together.

FIG. 5 is a flowchart showing an example of a mode switching criterion control process according to one embodiment of the present invention, and FIG. 6 is a drawing for explaining a mode ratio map form and a mode switching criterion adjustment form that can be applied to mode switching criterion control according to one embodiment of the present invention.

Referring to Fig. 5, the ratio range of the HEV mode and the EV mode according to the current SOC can be determined in the hybrid controller (240) (S510A). This step may be performed when the vehicle is started, may be performed periodically, and may be performed according to the variation amount or variation ratio condition of the SOC.

The determination of the ratio range can be performed in the form of determining at least one of the upper limit and the lower limit. In this case, the upper limit and the lower limit may be applied with values determined in advance according to the SOC, or if the expected driving path is determined (for example, if the destination is set in the navigation system), the remaining distance, the average driving load of the expected driving path, etc. may be further considered. For example, if the remaining distance is short, the upper limit and the lower limit may be set with a larger margin, and if the average driving load is large, the upper limit and the lower limit may be set with a smaller margin.

Meanwhile, separately from the determination of the ratio range, the hybrid controller (240) can cumulatively collect the sensing values of the accelerator pedal sensor (APS) (S510B) and predict the probability for each driving mode based on this (S520).

The probability by driving mode can mean the probability based on one of the two modes, and can also be replaced by the ratio of the two modes. For example, if the probability of the HEV mode is 40% and the probability of the EV mode is 60%, it means 40% based on the HEV mode and 60% based on the EV mode, and the ratio of the two modes can mean 'HEV:EV = 4:6'.

In addition, the hybrid controller can manage the driver's accelerator pedal operation tendency information accumulated from the sensing values of the accelerator pedal sensor, and the accelerator pedal operation tendency information can be in the form of a distribution map with the accelerator pedal sensor value converted into the required power and the frequency as different axes, but is not necessarily limited thereto.

Here, the probability for each driving mode can be predicted based on the cumulative distribution of the value converted from the APS to the required power (or required torque) and the currently set mode switching criterion power. At this time, the currently set mode switching criterion may be the last adjusted value if the mode switching criterion adjustment according to the present embodiment has already been performed, and may be a default value preset based on the system efficiency before the adjustment, but is not necessarily limited thereto. For example, if a required power distribution in the form of FIG. 4 is obtained as a result of the cumulative collection of the APS sensing value, according to the currently set mode switching criterion (410), the area ratio corresponding to a1 becomes the probability of the EV mode, and the area ratio corresponding to a2 becomes the probability of the HEV mode.

The hybrid controller (240) can determine whether the driving mode probability obtained as described above satisfies the ratio range of the HEV mode and the EV mode according to the current SOC (S530). This will be described with reference to (a) of FIG. 6. In (a) of FIG. 6, the horizontal axis represents SOC, and the vertical axis represents the ratio of the EV mode and the HEV mode, respectively. For example, if the vertical axis value for a specific SOC on the graph is close to the EV axis at the top, it means that the EV mode driving probability is high, and if it is close to the HEV axis at the bottom, it means that the HEV mode driving probability is high. In addition, the colored area (610) in the center of the graph may mean the ratio range for each mode for the current SOC obtained in step S510. Accordingly, the hybrid controller (240) can determine that the mode-specific ratio range for the current SOC is satisfied if the driving mode-specific probability obtained at step S520 is located within the colored area (610), and that the mode-specific ratio range is not satisfied if the probability commonly corresponds to ① in CASE #A and CASE #B.

The hybrid controller (240) can maintain the currently set mode switching criteria (S550) if the driving mode-specific probability obtained at step S520 satisfies the mode-specific ratio range for the current SOC obtained at step S510A (Yes in S530).

Conversely, if the driving mode-specific probability obtained at step S520 does not satisfy the mode-specific ratio range for the current SOC obtained at step S510A (No of S530), the mode switching criteria can be adjusted to satisfy the mode-specific ratio range (S540).

For example, in the CASE #A situation where the SOC is relatively low as shown in (a) and (b) of FIG. 6, the mode switching reference power can be lowered to increase the ratio of the HEV mode so that the ratio range (610) for each mode is satisfied at the corresponding SOC.

As another example, in the CASE #B situation where the SOC is relatively high, as shown in (a) and (c) of FIG. 6, the mode switching reference power can be raised to increase the ratio of the EV mode so that the ratio range (610) for each mode is satisfied at the corresponding SOC.

To summarize the mode switching control method explained so far, the hybrid controller (240) adjusts the mode switching criteria so that the target EV/HEV mode ratio range can be satisfied for each current SOC, and the adjustment of the mode switching criteria uses the driving mode probability based on the accumulated distribution of the driver's accelerator pedal operation.

Therefore, unlike the general driving mode switching criterion adjustment method that simply classifies driver tendencies into categories such as soft/normal/aggressive and applies fixed values according to the classification results, there is an effect in which the target driving mode ratio according to the current SOC can be precisely adjusted according to the accumulated driver tendencies.

Meanwhile, whether or not the mode switching criteria are adjusted according to the driving control method described above can be output in a form that the driver can recognize. Specifically, the hybrid vehicle according to the embodiment can be equipped with a display device such as a cluster, a head unit, a display of an AVN (Audio/Video/Navigation) system, a head-up display (HUD), etc. When information on whether or not the mode switching criteria are changed according to the SOC and the driver's accelerator pedal operation tendency is acquired from the hybrid controller to the display device, the information can be displayed through the display device. This will be described with reference to FIG. 7.

FIG. 7 shows an example of a form of outputting that a change in mode switching criteria is performed according to one embodiment of the present invention.

Referring to FIG. 7, a hybrid vehicle according to an embodiment may output information in the form of text on whether or not to change the mode switching criteria according to the SOC and the driver's accelerator pedal operation tendency in an area (710) that allows arbitrary text display of a cluster (700).

Of course, these display forms are exemplary, and the text can be replaced with a flashing warning light in a fixed position, displayed in the form of an icon, or displayed on the battery gauge as a criterion for changing mode switching, etc., and various other variations are possible.

In addition, not only the display form but also the location where it is displayed can be changed to another location within the cluster, the AVN system, the display of the head unit, a head-up display, etc.

The above-described present invention can be implemented as a computer-readable code on a medium in 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, an optical data storage device, etc.

Accordingly, the above detailed description should not be construed as restrictive in all respects but should be considered as illustrative. The scope of the invention should be determined by a reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are intended to be included in the scope of the invention.

Claims (15)

A step of determining a target ratio range between a first driving mode using only a driving motor and a second driving mode using at least an engine, based on the current battery state (SOC: State Of Charge);
A step for predicting a driving mode ratio based on the accumulated driver's accelerator pedal operation tendency information and the currently set mode switching criteria;
a step of determining whether the predicted driving mode ratio satisfies the target ratio range; and
A control method for a hybrid vehicle, comprising: a step of adjusting the mode switching criterion based on the accumulated driver's accelerator pedal operation tendency information so as to satisfy the target ratio range when the predicted driving mode ratio as a result of the judgment does not satisfy the target ratio range. In the first paragraph,
The above accumulated driver accelerator pedal operation tendency information is as follows:
A control method for a hybrid vehicle, comprising a distribution map in which an accelerator pedal sensor value is converted into a demand power value and a frequency are on different axes. In the second paragraph,
The step of predicting the above driving mode ratio is:
A control method for a hybrid vehicle, performed based on the ratio of two different areas divided by applying the currently set mode switching criteria to the above distribution map. In the second paragraph,
The above adjustment steps are:
A method for controlling a hybrid vehicle, performed based on the above distribution map. In the first paragraph,
The above target ratio range is:
A method for controlling a hybrid vehicle, wherein at least one of an upper limit and a lower limit for a ratio between the first driving mode and the second driving mode is set according to the current battery state (SOC: State Of Charge). In the first paragraph,
The above target ratio range is:
A control method for a hybrid vehicle, wherein the ratio of the first driving mode is set higher than the ratio of the second driving mode as the current battery status is higher. In the first paragraph,
A method for controlling a hybrid vehicle, further comprising the step of outputting, through a display device, whether or not the above mode switching criteria are adjusted. A computer-readable recording medium having recorded thereon a program for executing a method for controlling a hybrid vehicle according to any one of claims 1 to 7. An accelerator pedal sensor that detects the driver's accelerator pedal operation amount; and
A hybrid vehicle comprising a hybrid controller which determines a target ratio range between a first driving mode using only a driving motor and a second driving mode using at least an engine based on a current battery state (SOC: State Of Charge), predicts a driving mode ratio based on the driver's accelerator pedal operation tendency information accumulated and collected through the accelerator pedal sensor and a currently set mode switching criterion, and adjusts the mode switching criterion based on the accumulated driver's accelerator pedal operation tendency information so as to satisfy the target ratio range when the predicted driving mode ratio does not satisfy the target ratio range. In Article 9,
The above accumulated driver accelerator pedal operation tendency information is as follows:
A hybrid vehicle comprising a distribution map with different axes for frequency and a value converted into a required power by the sensor value of the accelerator pedal sensor. In Article 10,
The above hybrid controller,
A hybrid vehicle, which predicts the driving mode ratio based on the ratio of two different areas divided by applying the currently set mode switching criteria to the above distribution map. In Article 10,
The above hybrid controller,
A hybrid vehicle that adjusts the mode switching criteria using the above distribution map. In Article 9,
The above target ratio range is:
A hybrid vehicle, wherein at least one of an upper limit and a lower limit for a ratio between the first driving mode and the second driving mode is set according to the current battery state (SOC: State Of Charge). In Article 9,
The above target ratio range is:
A hybrid vehicle, wherein the ratio of the first driving mode is set higher than the ratio of the second driving mode as the current battery status is higher. In Article 9,
A hybrid vehicle further comprising a display device that outputs whether the above mode switching criteria are adjusted.