U.S. patent application number 16/548128 was filed with the patent office on 2019-12-12 for apparatus and method for controlling start of engine for mild hybrid electric vehicle.
The applicant listed for this patent is HYUNDAI MOTOR COMPANY, KIA MOTORS CORPORATION. Invention is credited to Hwa Yong JANG.
Application Number | 20190375393 16/548128 |
Document ID | / |
Family ID | 59759192 |
Filed Date | 2019-12-12 |
United States Patent
Application |
20190375393 |
Kind Code |
A1 |
JANG; Hwa Yong |
December 12, 2019 |
APPARATUS AND METHOD FOR CONTROLLING START OF ENGINE FOR MILD
HYBRID ELECTRIC VEHICLE
Abstract
An apparatus for controlling a start of an engine for a mild
hybrid electric vehicle includes: a mild hybrid starter &
generator (MHSG) starting an engine; a first battery connected to
the MHSG through a first power cable and supplying electric power
to the MHSG; a low voltage DC-DC converter (LDC) converting voltage
supplied from the first battery into low voltage; a second battery
supplying the low voltage to an electric load that uses the low
voltage; an ignition switch including a first contact point and a
second contact point; a data detector detecting data for
controlling the engine start for a mild hybrid electric vehicle;
and a controller determining whether a charging condition of the
second battery is satisfied based on the data, and charging the
second battery with electric power of the first battery when the
charging condition of the second battery is satisfied.
Inventors: |
JANG; Hwa Yong;
(Hwaseong-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HYUNDAI MOTOR COMPANY
KIA MOTORS CORPORATION |
Seoul
Seoul |
|
KR
KR |
|
|
Family ID: |
59759192 |
Appl. No.: |
16/548128 |
Filed: |
August 22, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15367933 |
Dec 2, 2016 |
|
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16548128 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60W 10/06 20130101;
Y02T 10/72 20130101; B60W 2710/248 20130101; Y10S 903/93 20130101;
F02N 11/04 20130101; B60W 2710/06 20130101; H02J 7/007 20130101;
B60L 50/16 20190201; B60W 2510/244 20130101; F02N 2011/0888
20130101; B60K 6/26 20130101; B60W 20/10 20130101; F02N 11/0866
20130101; B60W 2710/08 20130101; B60L 50/61 20190201; B60W 10/26
20130101; B60W 2556/50 20200201; B60K 6/442 20130101; F02N 11/0803
20130101; Y02T 10/7072 20130101; B60L 2260/50 20130101; F02N
2300/2011 20130101; B60L 2210/10 20130101; Y02T 10/62 20130101;
B60K 6/485 20130101; H02J 7/342 20200101; Y02T 10/70 20130101; H02J
7/1423 20130101; B60W 2555/20 20200201; H02J 7/34 20130101; B60L
58/12 20190201; B60W 10/08 20130101; B60L 2240/62 20130101; F02N
2300/2002 20130101; Y02T 90/16 20130101; H02J 2310/40 20200101;
B60W 20/12 20160101 |
International
Class: |
B60W 20/10 20060101
B60W020/10; B60W 20/12 20060101 B60W020/12; B60K 6/26 20060101
B60K006/26; B60K 6/442 20060101 B60K006/442; B60W 10/06 20060101
B60W010/06; B60W 10/08 20060101 B60W010/08; B60W 10/26 20060101
B60W010/26 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 9, 2016 |
KR |
10-2016-0116720 |
Claims
1. An apparatus for controlling a start of an engine for a mild
hybrid electric vehicle, the apparatus comprising: a mild hybrid
starter and generator (MHSG) which starts an engine or generates
electric power by using an output of the engine; a first battery
which is connected to the MHSG through a first power cable and
supplies electric power to the MHSG or is charged with electric
power generated by the MHSG; a low voltage DC-DC converter (LDC)
which converts voltage supplied from the first battery into a low
voltage; a second battery which supplies the low voltage to an
electric load that uses the low voltage; an ignition switch which
includes a first contact point and a second contact point; a data
detector which detects data for controlling the engine start of a
mild hybrid electric vehicle; and a controller which determines
whether a charging condition of the second battery is satisfied
based on the data, and charges the second battery with electric
power of the first battery when the charging condition of the
second battery is satisfied, wherein the MHSG is connected with the
second battery through a second power cable, and wherein the
controller compares an estimated time with a reference time when a
destination is set, and determines whether the charging condition
of the second battery is satisfied when the estimated time is
shorter than the reference time.
2. An apparatus for controlling a start of an engine for a mild
hybrid electric vehicle, the apparatus comprising: a mild hybrid
starter and generator (MHSG) which starts an engine or generates
electric power by using an output of the engine; a first battery
which is connected to the MHSG through a first power cable and
supplies electric power to the MHSG or is charged with electric
power generated by the MHSG; a low voltage DC-DC converter (LDC)
which converts voltage supplied from the first battery into a low
voltage; a second battery which supplies the low voltage to an
electric load that uses the low voltage; an ignition switch which
includes a first contact point and a second contact point; a data
detector which detects data for controlling the engine start of a
mild hybrid electric vehicle; and a controller which determines
whether a charging condition of the second battery is satisfied
based on the data, and charges the second battery with electric
power of the first battery when the charging condition of the
second battery is satisfied, wherein the MHSG is connected with the
second battery through a second power cable, and wherein the
controller determines whether the first contact point of the
ignition switch is selected when a destination is not set, and
determines whether the charging condition of the second battery is
satisfied when the first contact point of the ignition switch is
selected.
3. The apparatus of claim 1, wherein the charging condition of the
second battery is satisfied when an outdoor temperature is equal to
or lower than a reference temperature and a state of charge (SOC)
of the second battery is equal to or lower than a first reference
SOC.
4. The apparatus of claim 1, wherein when the second contact point
of the ignition switch is selected, the controller determines
whether a discharging condition of the second battery is satisfied
based on the data, and when the discharging condition of the second
battery is satisfied, the controller starts the engine by supplying
electric power of the second battery to the MHSG through the second
power cable.
5. The apparatus of claim 4, wherein the discharging condition of
the second battery is satisfied when the SOC of the first battery
is equal to or lower than a second reference SOC.
6. The apparatus of claim 4, wherein when the discharging condition
of the second battery is not satisfied, the controller starts the
engine by supplying electric power of the first battery to the
MHSG.
7. The apparatus of claim 1, wherein the data detector includes: a
navigation device which determines a route of the mild hybrid
electric vehicle from a current position to the destination; a
first SOC sensor which detects the SOC of the first battery; a
second SOC sensor which detects the SOC of the second battery; and
an outdoor temperature sensor which detects an outdoor temperature
outside the mild hybrid electric vehicle.
8. The method of claim 9, wherein the step of determining whether
the charging condition of the second battery is satisfied is
performed when a destination is set and an estimated time is
shorter than a reference time.
9. A method for controlling a start of an engine for a mild hybrid
electric vehicle, wherein the mild hybrid electric vehicle
includes: a mild hybrid starter & generator (MHSG) which starts
an engine or generates electric power by using an output of the
engine; a first battery which is connected to the MHSG through a
first power cable; a low voltage DC-DC converter (LDC) which
converts voltage supplied from the first battery into low voltage;
a second battery which is connected to the MHSG through a second
power cable and supplies the low voltage to an electric load that
uses the low voltage; and an ignition switch which includes a first
contact point and a second contact point, the method comprising
steps of: detecting, by a data detector, data for controlling the
engine start; determining, by a controller, whether a charging
condition of the second battery is satisfied based on the data;
charging, by the controller, the second battery with electric power
of the first battery when the charging condition of the second
battery is satisfied; determining, by the controller, whether a
discharging condition of the second battery is satisfied based on
the data when the second contact point of the ignition switch is
selected; and starting, by the controller, the engine by supplying
electric power of the second battery to the MHSG through the second
power cable when the discharging condition of the second battery is
satisfied, wherein the step of determining whether the charging
condition of the second battery is satisfied is performed when the
first contact point of the ignition switch is selected.
10. The method of claim 9, wherein the charging condition of the
second battery is satisfied when an outdoor temperature is equal to
or lower than a reference temperature and a state of charge (SOC)
of the second battery is equal to or lower than a first reference
SOC.
11. The method of claim 9, wherein the step of determining whether
the discharging condition of the second battery is satisfied is
performed when the second contact point of the ignition switch is
selected.
12. The method of claim 9, wherein the discharging condition of the
second battery is satisfied when the SOC of the first battery is
equal to or lower than a second reference SOC.
13. The method of claim 9, further comprising starting the engine
by supplying electric power of the first battery to the MHSG when
the discharging condition of the second battery is not satisfied.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/367,933 filed on Dec. 2, 2016, which claims
the benefit of priority to Korean Patent Application No.
10-2016-0116720 filed in the Korean Intellectual Property Office on
Sep. 9, 2016, the entire content of which is incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present disclosure relates to a method and an apparatus
for controlling a start of an engine for a mild hybrid electric
vehicle.
BACKGROUND
[0003] As well known, a hybrid electric vehicle uses both an
internal combustion engine and a battery power source. That is, the
hybrid electric vehicle uses an efficient combination of power of
the internal combustion engine and power of a motor.
[0004] Based on a power sharing ratio between the engine and the
motor, the hybrid electric vehicle may be classified into a mild
type hybrid electric vehicle and a hard type hybrid electric
vehicle. The mild type hybrid electric vehicle (hereinafter,
referred to as a mild hybrid electric vehicle) includes a mild
hybrid starter & generator (MHSG), which starts the engine or
generates electric power by using an output of the engine, instead
of an alternator. The hard type hybrid electric vehicle is provided
with an integrated starter & generator (ISG) which starts the
engine or generates electric power by using the output of the
engine, and a drive motor which drives the vehicle, and the ISG and
the drive motor are separately provided.
[0005] In the case of the mild hybrid electric vehicle, there is no
traveling mode in which the vehicle is driven only by torque of the
MHSG, but torque of the engine may be supplemented by using the
MHSG in accordance with a traveling state, and a battery (e.g., a
48V battery) may be charged by regenerative braking. Therefore,
fuel economy of the mild hybrid electric vehicle may be
improved.
[0006] As a battery which supplies electric power to the MHSG or is
charged with electric power recovered by the MHSG, a lithium-ion
battery is used. That is, in order to exhibit optimum performance
of the MHSG, a battery, which is fast in charging and discharging
speeds and has improved durability, is used.
[0007] However, the lithium-ion battery has a problem in that
energy storage performance and charging and discharging efficiency
deteriorate in an extremely low-temperature state. Therefore, at a
below zero temperature, the lithium-ion battery cannot supply
sufficient electric power to the MHSG, and as a result, the engine
cannot be started.
[0008] The above information disclosed in this Background section
is only for enhancement of understanding of the background of the
invention, and therefore, it may contain information that does not
form the prior art that is already known in this country to a
person of ordinary skill in the art.
SUMMARY
[0009] The present disclosure has been made in an effort to provide
an apparatus and a method for controlling a start of an engine for
a mild hybrid electric vehicle, which is capable of starting an
engine by supplying sufficient electric power to a mild hybrid
starter & generator (MHSG) even at a low outdoor
temperature.
[0010] According to an exemplary embodiment of the present
disclosure, an apparatus for controlling a start of an engine for a
mild hybrid electric vehicle includes: a mild hybrid starter &
generator (MHSG) which starts an engine or generates electric power
by using an output of the engine; a first battery which is
connected to the MHSG through a first power cable and supplies
electric power to the MHSG or is charged with electric power
generated by the MHSG; a low voltage DC-DC converter (LDC) which
converts voltage supplied from the first battery into a low
voltage; a second battery which supplies the low voltage to an
electric load that uses the low voltage; an ignition switch which
includes a first contact point and a second contact point; a data
detector which detects data for controlling the engine start for a
mild hybrid electric vehicle; and a controller which determines
whether a charging condition of the second battery is satisfied
based on the data, and charges the second battery with electric
power of the first battery when the charging condition of the
second battery is satisfied, in which the MHSG is connected with
the second battery through a second power cable.
[0011] The controller may compare an estimated time with a
reference time when a destination is set, and may determine whether
the charging condition of the second battery is satisfied when the
estimated time is shorter than the reference time.
[0012] The controller may determine whether the first contact point
of the ignition switch is selected when a destination is not set,
and may determine whether the charging condition of the second
battery is satisfied when the first contact point of the ignition
switch is selected.
[0013] The charging condition of the second battery may be
satisfied when an outdoor temperature is equal to or lower than a
reference temperature and an SOC of the second battery is equal to
or lower than a first reference SOC.
[0014] When the second contact point of the ignition switch is
selected, the controller may determine whether a discharging
condition of the second battery is satisfied based on the data, and
when the discharging condition of the second battery is satisfied,
the controller may start the engine by supplying electric power of
the second battery to the MHSG through the second power cable.
[0015] The discharging condition of the second battery may be
satisfied when the SOC of the first battery is equal to or lower
than a second reference SOC.
[0016] When the discharging condition of the second battery is not
satisfied, the controller may start the engine by supplying
electric power of the first battery to the MHSG.
[0017] The data detector may include: a navigation device which
determines a route of the mild hybrid electric vehicle from a
current position to a destination; a first SOC sensor which detects
the SOC of the first battery; a second SOC sensor which detects the
SOC of the second battery; and an outdoor temperature sensor which
detects an outdoor temperature outside the mild hybrid electric
vehicle.
[0018] According to another exemplary embodiment of the present
disclosure, a method for controlling a start of an engine for a
mild hybrid electric vehicle includes: a mild hybrid starter &
generator (MHSG) which starts an engine or generates electric power
by using an output of the engine; a first battery which is
connected to the MHSG through a first power cable; a low voltage
DC-DC converter (LDC) which converts voltage supplied from the
first battery into low voltage; a second battery which is connected
to the MHSG through a second power cable and supplies the low
voltage to an electric load that uses the low voltage; and an
ignition switch which includes a first contact point and a second
contact point, the method including: detecting data for controlling
the engine start; determining whether a charging condition of the
second battery is satisfied based on the data; charging the second
battery with electric power of the first battery when the charging
condition of the second battery is satisfied; determining whether a
discharging condition of the second battery is satisfied based on
the data when the second contact point of the ignition switch is
selected; and starting the engine by supplying electric power of
the second battery to the MHSG through the second power cable when
the discharging condition of the second battery is satisfied.
[0019] The determining of whether the charging condition of the
second battery is satisfied may be performed when a destination is
set and an estimated time is shorter than a reference time.
[0020] The determining of whether the charging condition of the
second battery is satisfied may be performed when the first contact
point of the ignition switch is selected.
[0021] The charging condition of the second battery may be
satisfied when an outdoor temperature is equal to or lower than a
reference temperature and an SOC of the second battery is equal to
or lower than a first reference SOC.
[0022] The determining of whether the discharging condition of the
second battery is satisfied may be performed when the second
contact point of the ignition switch is selected.
[0023] The discharging condition of the second battery may be
satisfied when the SOC of the first battery is equal to or lower
than a second reference SOC.
[0024] The method for controlling a start of an engine for a mild
hybrid electric vehicle may further include starting the engine by
supplying electric power of the first battery to the MHSG when the
discharging condition of the second battery is not satisfied.
[0025] According to the exemplary embodiments of the present
disclosure as described above, it is possible to start the engine
by supplying sufficient electric power to the MHSG even in a state
in which the SOC of the first battery is not sufficient because of
a low outdoor temperature.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a block diagram illustrating a mild hybrid
electric vehicle according to an exemplary embodiment of the
present disclosure.
[0027] FIG. 2 is a block diagram illustrating an apparatus for
controlling a start of an engine for a mild hybrid electric vehicle
according to the exemplary embodiment of the present
disclosure.
[0028] FIG. 3 is a flowchart illustrating a process of charging a
second battery in a method for controlling a start of the engine
for a mild hybrid electric vehicle according to the exemplary
embodiment of the present disclosure.
[0029] FIG. 4 is a flowchart illustrating a process when the second
battery is discharged in the method of controlling a start of the
engine for a mild hybrid electric vehicle according to the
exemplary embodiment of the present disclosure
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0030] Hereinafter, exemplary embodiments of the present disclosure
will be described in detail with reference to the accompanying
drawings so that those skilled in the technical field to which the
present disclosure pertains may easily carry out the exemplary
embodiments. However, the present disclosure is not limited to the
exemplary embodiments to be described below and may be specified as
other aspects.
[0031] A part irrelevant to the description will be omitted to
clearly describe the present disclosure, and the same or similar
constituent elements will be designated by the same reference
numerals throughout the specification.
[0032] In addition, each configuration illustrated in the drawings
is arbitrarily shown for understanding and ease of description, but
the present disclosure is not limited thereto.
[0033] FIG. 1 is a block diagram illustrating a mild hybrid
electric vehicle according to an exemplary embodiment of the
present disclosure.
[0034] As illustrated in FIG. 1, a mild hybrid electric vehicle
according to an exemplary embodiment of the present disclosure
includes an engine 10, a transmission 20, a mild hybrid starter
& generator (MHSG) 30, a first battery 40, a low voltage DC-DC
converter (LDC) 50, a second battery 60, an electric load 70, a
differential gear 80, and wheels 90.
[0035] The engine 10 generates a torque by combusting fuel. Various
engines such as a gasoline engine, a diesel engine, and a liquefied
petroleum injection (LPI) engine may be used as the engine 10.
[0036] Power transmission of the mild hybrid electric vehicle is
performed such that the torque of the engine 10 is transmitted to
an input shaft of the transmission 20, and a torque outputted from
an output shaft of the transmission 20 is transmitted to an axle
via the differential gear 80. As the axle rotates the wheels 90,
the mild hybrid electric vehicle travels by torque of the engine
10.
[0037] The transmission 20 may be an automatic transmission or a
manual transmission. The automatic transmission controls hydraulic
pressure by operating a plurality of solenoid valves based on a
speed of the mild hybrid electric vehicle and a position of an
accelerator pedal, such that a shift gear is operated at a target
gear stage and a gear shift operation is automatically performed.
In a case of the manual transmission, a gear shift operation is
performed as a driver steps on a clutch pedal and moves a gear
lever to a desired gear stage.
[0038] The MHSG 30 converts electrical energy into mechanical
energy, or converts mechanical energy into electrical energy. That
is, the MHSG 30 may start the engine 10 or may generate electric
power by using output of the engine 10. In addition, the MHSG 30
may supplement the torque of the engine 10. The mild hybrid
electric vehicle may use a torque of the MHSG 30 as an auxiliary
power while using the combustion torque of the engine 10 as a main
power. The engine 10 and the MHSG 30 may be connected through a
belt 32.
[0039] The first battery 40 may supply electric power to the MHSG
30 through a first power cable 45, or may be charged with electric
power recovered by the MHSG 30. The first battery 40 may be a
lithium-ion battery which is a high-voltage battery (e.g., a 48 V
battery). The first battery 40 may be referred to as a main
battery. The lithium-ion battery is fast in charging and
discharging speeds and has good durability, but energy storage
performance and charging and discharging efficiency may deteriorate
in an extremely low-temperature state.
[0040] The LDC 50 converts voltage (e.g., 48 V) supplied from the
first battery 40 into low voltage (e.g., 12 V), and charges the
second battery 60.
[0041] The second battery 60 may be charged with electric power
supplied from the LDC 50. The second battery 60 may be an
absorptive glass mat (AGM) battery or a lead-acid battery as a low
voltage battery (e.g., a 12 V battery). The second battery 60 may
be referred to as an auxiliary battery. The second battery 60
supplies electric power to the electric load 70 that uses low
voltage (e.g., 12 V). The second battery 60 according to an
exemplary embodiment of the present disclosure may supply electric
power to the MHSG 30 through a second power cable 65.
[0042] The electric load 70 includes various electric or electronic
devices such as head lamps, an air conditioner, and wipers that use
electric power of the second battery 60.
[0043] FIG. 2 is a block diagram illustrating an apparatus for
controlling a mild hybrid electric vehicle according to an
exemplary embodiment of the present disclosure.
[0044] As illustrated in FIG. 2, the apparatus for controlling the
mild hybrid electric vehicle may include an ignition switch 110, a
data detector 120, a controller 130, the MHSG 30, the first battery
40, the LDC 50, the second battery 60, the first power cable 45,
and the second power cable 65.
[0045] The ignition switch 110 may include a plurality of contact
points. The plurality of contact points may include an OFF contact
point (hereinafter, referred to as a first contact point), an ACC
contact point, an ON contact point (hereinafter, referred to as a
second contact point), and a START contact point. When the first
contact point is selected, the engine 10 is turned off. When the
ACC contact point is selected, accessory devices such as a radio
may be used. When the ON contact point is selected, electronic
devices, which use voltage of the first battery 40 and the second
battery 60, may be used. When the second contact point is selected,
the engine 10 starts. The contact points of the ignition switch 110
may be selected by a start key or a start button.
[0046] The data detector 120 detects data for controlling the start
of the engine for a mild hybrid electric vehicle, and the data
detected by the data detector 120 is transferred to the controller
130. The data detector 120 may include a navigation device 121, a
global positioning system (GPS) 122, a first SOC sensor 123, a
second SOC sensor 124, and an outdoor temperature sensor 125. The
data detector 120 may further include detection units (e.g., an
accelerator pedal position detection unit, a brake pedal position
detection unit, and the like) for controlling the mild hybrid
electric vehicle.
[0047] The navigation device 121 determines a route of the mild
hybrid electric vehicle from the current position to a destination.
The navigation device 121 may include an input and output unit
which inputs and outputs information about route guidance, a
current position detection unit which detects information
associated with a current position of the vehicle, a memory which
stores map data required to calculate a route and data required to
guide the route, a control unit which searches a route and guides
the route, and a display unit which displays the route.
[0048] The GPS 122 receives radio waves from a GPS satellite, and
transmits related signals to the navigation device 121. The
navigation device 121 may calculate the current position of the
vehicle based on the signals.
[0049] The first SOC sensor 123 detects a state of charge (SOC) of
the first battery 40, and transmits signals associated with the SOC
to the controller 130. Instead of directly detecting the SOC of the
first battery 40, electric current and voltage of the first battery
40 may be measured, and then the SOC of the first battery 40 may be
predicted based on the electric current and the voltage of the
first battery 40.
[0050] The second SOC sensor 124 detects an SOC of the second
battery 60, and transmits signals associated with the SOC to the
controller 130.
[0051] The outdoor temperature sensor 125 detects an outdoor
temperature outside the mild hybrid electric vehicle, and transmits
signals associated with the outdoor temperature to the controller
130.
[0052] The controller 130 may control a start of the engine based
on the signals of the ignition switch 110 and the data detector
120. The controller 130 may supply electric power of the first
battery 40 to the MHSG 30, thereby starting the engine 10. In
addition, since the MHSG 30 is connected with the second battery 60
through the second power cable 65, the controller 130 may start the
engine 10 by supplying electric power of the second battery 60 to
the MHSG 30. To this end, the controller 100 may be implemented as
one or more processors operated by a preset program, and the preset
program may include a series of commands for performing respective
steps included in the following method for controlling a start of
the engine for a mild hybrid electric vehicle according to the
exemplary embodiment of the present disclosure. The controller 100
may be a general engine control unit (ECU).
[0053] Hereinafter, referring to FIGS. 3 and 4, the method for
controlling a start of the engine for a mild hybrid electric
vehicle according to the exemplary embodiment of the present
disclosure will be specifically described.
[0054] FIG. 3 is a flowchart illustrating a process of charging a
second battery in the method for controlling a start of the engine
for a mild hybrid electric vehicle according to the exemplary
embodiment of the present disclosure.
[0055] As illustrated in FIG. 3, the method for controlling a start
of the engine for a mild hybrid electric vehicle according to the
exemplary embodiment of the present disclosure starts by detecting
data for controlling the start of the engine 10 (S100). That is, in
a case in which a destination of the mild hybrid electric vehicle
is preset, the navigation device 121 may calculate an estimated
time required for the mild hybrid electric vehicle to move from the
current position to the destination. In addition, the first SOC
sensor 123 may detect the SOC of the first battery 40, the second
SOC sensor 124 may detect the SOC of the second battery 60, and the
outdoor temperature sensor 125 may detect an outdoor temperature
outside the mild hybrid electric vehicle.
[0056] Based on the signal of the navigation device 121, the
controller 130 determines whether a destination of the mild hybrid
electric vehicle is set (S110).
[0057] If it is determined in step S110 that the destination is
set, the controller 130 compares the estimated time with a
reference time (S120). The reference time may be set to a period of
time (e.g., 5 minutes) determined as an appropriate time by those
skilled in the art in consideration of the time required to charge
the second battery 60 by using electric power of the first battery
40.
[0058] If the estimated time is equal to or longer than the
reference time in step S120, the controller 130 continues to
monitor the estimated time.
[0059] If the estimated time is shorter than the reference time in
step S120, the controller 130 determines whether a charging
condition of the second battery 60 is satisfied (S130). The
charging condition of the second battery 60 may be satisfied in a
case in which the outdoor temperature is equal to or lower than a
reference temperature and the SOC of the second battery 60 is equal
to or lower than a first reference SOC. The reference temperature
may be set to a temperature determined as an appropriate
temperature by those skilled in the art in consideration of energy
storage performance of the first battery 40 in a low-temperature
state. The first reference SOC may be set to an SOC determined as
an appropriate SOC by those skilled in the art in consideration of
the SOC of the second battery 60 which is required to perform a
next start of the engine 10.
[0060] If the charging condition of the second battery 60 is
satisfied in step S130, the controller 130 charges the second
battery 60 with electric power of the first battery 40 (S140). That
is, the controller 130 converts voltage, which is supplied from the
first battery 40, into low voltage through the LDC 50, and charges
the second battery 60. The controller 130 may charge the second
battery 60 until the SOC of the second battery 60 reaches an SOC
required to perform a next start of the engine 10. Therefore, when
the mild hybrid electric vehicle reaches the destination and the
engine 10 is turned off, the SOC of the second battery 60 may be
sufficient to perform a next start of the engine 10.
[0061] If it is determined in step S110 that the destination is not
set, the controller 130 determines whether the first contact point
of the ignition switch 110 is selected (S150). The first contact
point may be the OFF contact point of the ignition switch 110.
[0062] If the first contact point is not selected in step S150, the
controller 130 continues to monitor whether the first contact point
is selected.
[0063] If the first contact point is selected in step S150, the
controller 130 determines whether the charging condition of the
second battery 60 is satisfied (S130).
[0064] If the charging condition of the second battery is satisfied
in step S130, the controller 130 converts voltage, which is
supplied from the first battery 40, into low voltage through the
LDC 50 and charges the second battery 60. That is, even when the
engine 10 is turned off, the controller 130 may operate the LDC 50
until the SOC of the second battery 60 reaches the SOC required to
perform a next start of the engine 10.
[0065] FIG. 4 is a flowchart illustrating a process when the second
battery is discharged in the method of controlling a start of the
engine for a mild hybrid electric vehicle according to the
exemplary embodiment of the present disclosure.
[0066] As illustrated in FIG. 4, the controller 130 determines
whether the second contact point of the ignition switch 110 is
selected (S200). The second contact point may be the START contact
point of the ignition switch 110.
[0067] If the second contact point is not selected in step S200,
the method for controlling the mild hybrid electric vehicle
according to the exemplary embodiment of the present disclosure
ends.
[0068] If the second contact point is selected in step S200, the
controller 130 determines whether a discharging condition of the
second battery 60 is satisfied (S210). The discharging condition of
the second battery 60 may be satisfied in a case in which the SOC
of the first battery 40 is equal to or lower than a second
reference SOC. The second reference SOC may be set to an SOC
determined as an appropriate SOC by those skilled in the art in
consideration of the SOC of the first battery 40 which is required
to start the engine 10.
[0069] If the discharging condition of the second battery 60 is
satisfied in step S210, the controller 130 may start the engine 10
by supplying electric power of the second battery 60 to the MHSG 30
through the second power cable 65 (S220).
[0070] If the discharging condition of the second battery 60 is not
satisfied in step S210, the controller 130 may start the engine 10
by supplying electric power of the first battery 40 to the MHSG 30
(S230).
[0071] According to the exemplary embodiment of the present
disclosure as described above, it is possible to start the engine
10 by supplying sufficient electric power to the MHSG 30 even in a
state in which the SOC of the first battery 40 is not sufficient
because of a low outdoor temperature.
[0072] While this invention has been described in connection with
what is presently considered to be practical exemplary embodiments,
it is to be understood that the invention is not limited to the
disclosed embodiments, but on the contrary, is intended to cover
various modifications and equivalent arrangements included within
the spirit and scope of the appended claims.
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