APPARATUS AND METHOD FOR CONTROLLING MILD HYBRID ELECTRIC VEHICLE

An apparatus for controlling mild hybrid electric vehicle may include: an engine; a mild hybrid starter and generator (MHSG) starting the engine or generating power by an output of the engine; a data receiving device receiving at least vehicle speed data, vehicle location data and traffic information; and a controller configured to control a state of charge (SOC) criteria for idle stop restriction based on the data supplied from the data receiving device.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2017-0177244 filed on Dec. 21, 2017, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an apparatus and method for controlling mild hybrid electric vehicle, and more particularly, to an apparatus for controlling mild hybrid electric vehicle controlling an idle stop entry condition according to driving conditions and a method thereof.

Description of Related Art

As is generally known in the art, a hybrid electric vehicle utilizes an internal combustion engine and a battery power source together. The hybrid electric vehicle efficiently combines a torque of the internal combustion engine and a torque of a motor.

Hybrid electric vehicles may be divided into a hard type and a mild type according to power sharing ratio between an engine and a motor. In the case of the mild type of hybrid electric vehicle (hereinafter referred to as a mild hybrid electric vehicle), a mild hybrid starter & generator (MHSG) configured to start the engine or generate electricity according to an output of the engine is used instead of an alternator. In the case of the hard type of hybrid electric vehicle, a driving motor configured for generating driving torque is used in addition to an integrated starter & generator (ISG) configured to start the engine or generate electricity.

The MHSG may assist torque of the engine according to running states of the vehicle and may charge a battery (e.g., 48 V battery) through regenerative braking. Accordingly, fuel efficiency of the mild hybrid electric vehicle may be improved.

The mild hybrid electric vehicle provides idle stop mode to prevent unnecessary idling and fuel consumption when the engine power is not used.

However, there is a problem that, if the frequency of entering idle stop mode is high, durability of the battery may decrease rapidly and the driver may experience discomfort. when the vehicle enters the idle stop mode frequently when the vehicle is in a dangerous section, the risk of an accident because of not immediate engine start may increase

BRIEF SUMMARY

Various aspects of the present invention are directed to providing an apparatus and method for controlling mild hybrid electric vehicle which may decrease the risk of the accident and increase the durability of the battery by reducing the frequency of entering the idle stop in the dangerous section.

An apparatus configured for controlling mild hybrid electric vehicle according to an exemplary embodiment of the present invention may include: an engine; a mild hybrid starter and generator (MHSG) starting the engine or generating power by an output of the engine; a data receiving device receiving at least vehicle speed data, vehicle location data and traffic information; and a controller configured to control an SOC criteria for idle stop restriction based on the data supplied from the data receiving device.

When the vehicle speed is less than a predetermined speed, the controller may determine whether the vehicle is in a dangerous section, and when the vehicle is determined to be in the dangerous section, the controller may increase an SOC criteria for idle stop restriction from a default SOC value to an increased SOC value.

When the vehicle speed is equal to or greater than the predetermined speed, the controller may maintain the SOC criteria for idle stop restriction at the default SOC value.

When the vehicle is determined to be out of the dangerous section, the controller may decrease the SOC criteria for idle stop restriction from the increased SOC value to the default SOC value.

When the vehicle is determined to be still in the dangerous section, the controller may maintain the SOC criteria for idle stop restriction at the increased SOC value.

The traffic information may include navigation information, and the controller may determine the vehicle to be in the dangerous section when the vehicle is at least on an intersection, a railway, or an accident prone area.

A method for controlling mild hybrid electric vehicle according to an exemplary embodiment of the present invention may include: determining whether a speed of the vehicle less than a predetermined speed; when the vehicle speed is less than the predetermined speed, determining whether the vehicle is in a dangerous section based on a vehicle location information and a traffic information; and when the vehicle is determined to be in the dangerous section, increasing an SOC criteria for idle stop restriction from a default SOC value to an increased SOC value.

The method may further include; when the vehicle speed is equal to or greater than the predetermined speed, maintaining the SOC criteria for idle stop restriction at the default SOC value.

The method may further include; when the vehicle is determined to be out of the dangerous section, decreasing the SOC criteria for idle stop restriction from the increased SOC value to the default SOC value.

The method may further include; when the vehicle is determined to be still in the dangerous section, maintaining the SOC criteria for idle stop restriction at the increased SOC value. The traffic information may include navigation information, and in the step determining whether the vehicle is in the dangerous section, the vehicle may be determined to be in the dangerous section when the vehicle is at least on an intersection, a railway, or an accident prone area.

Various aspects of the present invention are directed to providing an apparatus and method for controlling mild hybrid electric vehicle which may decrease the risk of the accident and increase the durability of the battery by reducing the frequency of entering the idle stop in the dangerous section.

DETAILED DESCRIPTION

In the following detailed description, various exemplary embodiments of the present application will be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. However, the present invention is not limited the exemplary embodiments which are described herein, and may be modified in various different ways.

Parts which are not related with the description are omitted for clearly describing the exemplary embodiment of the present invention, and like reference numerals refer to like or similar elements throughout the specification.

Since each component in the drawings is arbitrarily illustrated for easy description, the present invention is not particularly limited to the components illustrated in the drawings.

FIG. 1is a block diagram of a mild hybrid electric vehicle according to an exemplary embodiment of the present invention.

As shown inFIG. 1, a mild hybrid electric vehicle1according to an exemplary embodiment of the present invention includes an engine10, a transmission110, a mild hybrid starter & generator (MHSG)120, a battery130, a differential gear apparatus140, a wheel150and an auxiliary battery160.

In connection with torque transmission of the mild hybrid electric vehicle1, torque generated from the engine10is transmitted to an input shaft of the transmission110, and a torque output from an output shaft of the transmission110is transmitted to an axle via the differential gear apparatus140. The axle rotates the wheel150so that the mild hybrid electric vehicle runs by the torque generated from the engine10.

The MHSG120starts the engine10or generates electricity according to an output of the engine10. Furthermore, the MHSG120may assist the torque of the engine10. In other words, the torque of the engine10may be used as main torque, and a torque of the MHSG120may be used as auxiliary torque. The MHSG120may be an inverter-integrated MHSG.

The battery130may supply electricity to the MHSG120, and may be charged through electricity recovered by the MHSG120in a regenerative braking mode. The battery130may have 48 V voltage. The battery130may be a LDC-integrated battery including a LDC (low voltage DC-DC converter) which converts a voltage supplied form the battery130into a low voltage. The mild hybrid electric vehicle1may further include an auxiliary battery160charged with the low voltage converted by the LDC, and configured to supply low voltage (e.g., 12V) power to electronic loads of the mild hybrid electric vehicle1.

FIG. 2is a diagram illustrating a portion of an apparatus configured for controlling mild hybrid electric vehicle according to an exemplary embodiment of the present invention.

As shown inFIG. 2, the apparatus controlling mild hybrid electric vehicle according to an exemplary embodiment of the present invention may further include a controller170and a data receiving device180.

The controller170may control the idle stop operation of the vehicle1based on the data like vehicle speed information and vehicle location information supplied from the data receiving device180.

The data receiving device180may receive the data necessary for controlling the idle stop operation and supply it to the controller170. The data receiving device may include a vehicle speed detector181, location information module183and SOC detector185. The data receiving device180may further include detectors or devices receiving data necessary for controlling the mild hybrid electric vehicle (e.g., engine speed detector, acceleration detector).

The vehicle speed detector181may detect the speed of the vehicle1and generate vehicle speed data. The controller170may get the vehicle speed data necessary for controlling the idle stop operation through the vehicle speed detector181.

The location information module183may receive at least location information related to the vehicle1and traffic information. The location information related to the vehicle1may be Global Positioning System (GPS) information. The traffic information may be navigation information or other location-based information supplied from a traffic information service provider, and may include information related to a dangerous section such as intersection, railway or accident prone area. The controller170may get the vehicle location information and the traffic information necessary for controlling the idle stop operation through the location information module183.

The SOC detector185may detect a state of charge (SOC) value of the battery130and generate an SOC data. The controller170may get the SOC data necessary for controlling the idle stop operation through the SOC detector185.

The controller170may get the SOC data necessary for controlling the idle stop operation through the SOC detector185. When the SOC value of the battery130detected by the SOC detector185is less than the SOC criteria for idle stop restriction, the controller may restrict the vehicle from entering idle stop.

Hereinafter, a method for controlling mild hybrid electric vehicle according to an exemplary embodiment of the present invention will be described with reference toFIG. 3.

FIG. 3is a flowchart illustrating the method for controlling mild hybrid electric vehicle according to an exemplary embodiment of the present invention.

As shown inFIG. 3, when the engine starts at step S11, the controller170determines whether the vehicle speed is less than a predetermined speed at step S13. The predetermined speed may be set to a value determined by a person of ordinary skill in the art to be suitable for the idle stop operation control. For example, the predetermined speed may be 30 kph.

When the vehicle speed is equal to or greater than the predetermined speed at step S13, the controller170enters a normal mode in which the SOC criteria for idle stop restriction is set as a default SOC value at step S23. The default SOC value may be set to a value determined by a person of ordinary skill in the art to be enough for the reliable engine start-up after idle stop in general situation. For example, the default SOC value may be 50% of the maximum SOC value of the battery130.

When the vehicle speed is less than the predetermined speed at step S13, the controller170determines whether the vehicle1is in a dangerous section based on vehicle location information and traffic information at step S15. The controller170may determine that the vehicle1is in the dangerous section when the vehicle is located on intersections, railways, or accident prone area.

In an exemplary embodiment of the present invention, the accident prone area may be an area in which the vehicle accident occurs more than an average value, e.g., 50% of vehicle accident in a country or a town.

The dangerous section may further include other places in which a person of ordinary skill in the art determines that a vehicle may be easily exposed to a dangerous situation.

When the controller170determines that the vehicle1is not in the dangerous section at step S17, the controller170enters the normal mode at step S23.

When the controller170determines that the vehicle1is in the dangerous section at step S17, the controller170increases the SOC criteria for idle stop restriction from the default SOC value to the increased SOC value at step S19. The increased SOC value may be set to a value determined by a person of ordinary skill in the art to be enough for the reliable engine start-up after idle stop when the vehicle is in the dangerous section. For example, the increased SOC value may be 90% of the maximum SOC value of the battery130.

The frequency with which the vehicle1enters idle stop may be reduced if the controller170increases the SOC criteria for idle stop restriction when the vehicle1in the dangerous section. This may reduce the risk of the vehicle becoming difficult to timely avoid dangerous situations due to the time it takes to start the engine10again.

Furthermore, even if the vehicle1enters idle stop in the dangerous section, it is made to have high enough SOC value of the battery130to ensure more reliable and quick engine start-up. Accordingly, startability of the engine may be improved and the safety of the mild hybrid electric vehicle1may be ensured when the vehicle1is in the dangerous section.

On the other hand, durability of the battery130may be improved because of the decreased frequency of unnecessary idle stop entry.

The controller170determines whether the vehicle1passed and got out of the dangerous section at step S21.

When the controller170determines that vehicle1is still in the dangerous section at step S21, the controller170maintains the SOC criteria for idle stop restriction at the increased SOC value.

When the controller determines that vehicle1passed the dangerous section at step S21, the controller170enters normal mode at step S23. In other words, the controller170decreases the SOC criteria for idle stop restriction from the increased SOC value to the default SOC value.