U.S. patent application number 10/897695 was filed with the patent office on 2006-01-26 for electrical storage device heater for vehicle.
Invention is credited to Pax Maguire, Jacob Mathews, Patrick Padgett, Douglas Zhu.
Application Number | 20060016793 10/897695 |
Document ID | / |
Family ID | 34912819 |
Filed Date | 2006-01-26 |
United States Patent
Application |
20060016793 |
Kind Code |
A1 |
Zhu; Douglas ; et
al. |
January 26, 2006 |
Electrical storage device heater for vehicle
Abstract
A heater system for an electrical storage device, such as a high
voltage traction battery, is connectable to an external AC power
source maintain a proper temperature of the battery as long as the
system remains connected to the external power source. The battery
temperature can be maintained at a level that ensures that the
vehicle will start even in extremely cold climates. The heater
system includes a heater disposed within the battery itself. Other
system components, such as an AC/DC converter and a control module,
may be connected to the battery heater system outside of the
battery, allowing the battery heater system to act as a modular
component that can be easily included in or excluded from a vehicle
as an option, either alone or in a package with an engine block
heater. The battery heater system is designed so that it can be
connected along with the engine block heater to the AC power source
using a single common connector.
Inventors: |
Zhu; Douglas; (Canton,
MI) ; Mathews; Jacob; (Canton, MI) ; Maguire;
Pax; (Ann Arbor, MI) ; Padgett; Patrick;
(Detroit, MI) |
Correspondence
Address: |
CARLSON, GASKEY & OLDS, P.C.
400 WEST MAPLE ROAD
SUITE 350
BIRMINGHAM
MI
48009
US
|
Family ID: |
34912819 |
Appl. No.: |
10/897695 |
Filed: |
July 23, 2004 |
Current U.S.
Class: |
219/205 |
Current CPC
Class: |
H01M 10/63 20150401;
B60K 6/28 20130101; Y02T 10/70 20130101; B60L 2210/30 20130101;
F02N 11/0862 20130101; F02N 11/0866 20130101; H01M 10/615 20150401;
F02N 11/14 20130101; F02N 19/02 20130101; B60L 58/27 20190201; F02N
2200/064 20130101; Y02E 60/10 20130101; B60K 2001/008 20130101;
Y02T 10/72 20130101; B60W 2510/244 20130101; B60L 58/24 20190201;
B60W 2510/246 20130101 |
Class at
Publication: |
219/205 |
International
Class: |
B60L 1/02 20060101
B60L001/02 |
Claims
1. A system for heating an electrical storage device in a vehicle,
the system being connectable to an external power source,
comprising: a heater coupled to the electrical storage device; a
switch for selectively coupling the external power source to the
heater; a controller that receives an input corresponding to a
temperature of the electrical storage device and operates the
switch based on at least the electrical storage device
temperature.
2. The system of claim 1, wherein the heater comprises at least one
thermoelectric heating element.
3. The system of claim 1, wherein the external power source is an
AC power source and wherein the system is connected to the AC power
source.
4. The system of claim 1, further comprising an AC/DC converter
that is connectable to the AC power source and operable to power
the heater.
5. The system of claim 4, wherein the controller controls the
switch based on at least one of the electrical storage device
temperature, an AC/DC output from the AC/DC converter, and a key
on/off condition.
6. The system of claim 4, wherein at least one of the AC/DC
converter, the switch, and the controller are disposed outside the
electrical storage device.
7. The system of claim 1, wherein the external power source is a
supplemental electrical power source disposed in the vehicle.
8. The system of claim 7, further comprising a DC/DC converter that
is connectable to the supplemental electrical power source.
9. A vehicle, comprising: an engine block heater; an electrical
storage device heater system, wherein the engine block heater and
the electrical storage device heater system are jointly connectable
to an external power source, and the electrical storage device
heater system having a heater for heating an electrical storage
device in the vehicle, a switch that selectively couples the heater
to the external power source, and a controller that receives an
input corresponding to an electrical storage device temperature and
operates the switch based on at least the electrical storage device
temperature.
10. The vehicle of claim 9, wherein the external power source is an
AC power source and wherein the electrical storage device heater
system further comprises an AC/DC converter disposed between the
external power source and the heater.
11. The vehicle of claim 10, wherein the controller controls the
switch based on at least one of the electrical storage device
temperature, an AC/DC output from the AC/DC converter, and a key
on/off condition.
12. The vehicle of claim 10, wherein at least one of the AC/DC
converter, the switch, and the controller are disposed outside the
electrical storage device.
13. The vehicle of claim 9, wherein the external power source is a
supplemental electrical power source.
14. A method of regulating an electrical storage device temperature
in an electrical storage device heater system that is connectable
to an external power source, the method comprising: checking an
electrical storage device temperature; checking whether the system
is connected to the external power source; closing the switch to
connect the heater to the external power source if the electrical
storage device temperature when the electrical storage device
temperature falls below the temperature threshold and when the
system is connected to the external power source; and opening the
switch to disconnect the heater from the external power source if
the electrical storage device temperature falls above the
temperature threshold.
15. The method of claim 14, wherein the step of periodically
checking the electrical storage device temperature comprises:
entering a sleep mode for a predetermined time period; and checking
the electrical storage device temperature during a wake-up
mode.
16. The method of claim 15, further comprising re-entering the
sleep mode after at least one of the closing step and the opening
step.
17. The method of claim 14, wherein the step of opening the switch
is conducted if the system is not connected to the external power
source.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates generally to thermal controls
for an electrical storage device in a vehicle. More particularly,
the present invention relates to a system and method for heating
the electrical storage device.
BACKGROUND OF THE INVENTION
[0002] Electric and hybrid electric vehicles have become
increasingly popular to meet the demand for fuel-efficient,
environmentally-friendly transportation. Such vehicles often
include an electrical storage device, such as a high-voltage
traction battery, for powering an electric motor to drive the
vehicle, either alone or in conjunction with an internal combustion
engine, fuel cell engine, or other prime mover.
[0003] Currently available electric and hybrid electric vehicles
tend to operate more effectively in moderate and warm climates and
less effectively in extremely cold climates. This is because high
voltage traction batteries tend to lose power as battery cell
temperature drops (e.g., below approx. 20.degree. C.). This power
decrease results in reduced vehicle performance, fuel economy and
drivability. At extremely low temperatures, the traction battery
may have insufficient power to even start the vehicle.
[0004] Maintaining a proper battery temperature is desirable to
ensure optimal vehicle performance in many different climates.
Sustaining the battery temperature at a desired level can be
challenging because the battery temperature can be affected by many
factors, such as the battery condition, the battery cell
temperature, the battery charge condition when the vehicle is
turned off, and the ambient temperature. Self-powered battery
heaters are able to maintain a minimum battery temperature level
only for short time periods because the amount of power available
for heating is limited by the storage capacity of the battery
itself. Thus, self-powered battery heaters are unsuitable when the
battery needs to be heated for an extended time period and/or when
the battery needs to be warmed to a higher temperature to ensure
optimal vehicle performance.
[0005] As such, there is a need for a system that can maintain a
battery temperature to a level that ensures reliable starting of an
electric or hybrid vehicle. There is also a need for a system that
can maintain a proper battery temperature in a controlled manner to
ensure optimum vehicle performance.
SUMMARY OF THE INVENTION
[0006] The invention is generally directed to a battery heater
system that can be connected to an external power source outside a
high-voltage vehicle battery to maintain a proper temperature of
the high-voltage battery as long as the system remains connected to
the external power source. The external power source can be, for
example, a separate low-voltage battery or a power source outside
the vehicle itself. The battery temperature can be maintained at a
level that ensures optimal battery performance as well as a minimum
level that ensures the vehicle will start in any climate. The
high-voltage battery itself can be any appropriate vehicle battery,
such as a high voltage traction battery.
[0007] In one embodiment, the system includes a battery heater,
such as a heater containing thermoelectric heater elements,
disposed within the battery system itself. Other heater system
components, such as a converter and a controller, may be connected
to the heater either inside or outside the battery system. Keeping
other system components outside the battery system allows the
battery heater system to act as a modular component that can be
easily included as a part of the battery itself or as part of an
optional vehicle heating package. Moreover, placing the converter
and/or the controller outside the battery allows the battery heater
system to be easily omitted from vehicles operating in climates
that do not require battery heating.
[0008] These and other features of the present invention can be
best understood from the following specification and drawings, the
following of which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a block diagram illustrating a battery heater
system according to one embodiment of the invention;
[0010] FIG. 2 is a block diagram illustrating a battery heater
system according to another embodiment of the invention;
[0011] FIG. 3 is a block diagram illustrating an example of the
battery heater system in conjunction with an engine block heater;
and
[0012] FIG. 4 is a flow diagram illustrating a method for
controlling the battery heater according to one embodiment of the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0013] FIG. 1 is a block diagram illustrating components of a
battery heater system 100 according to one embodiment of the
invention. Generally, the invention is directed to a vehicle
battery heater system 100 that is powered by an external power
source e.g., a 120V AC power source outside the vehicle or a
supplemental low-voltage or accessory battery on-board the vehicle)
outside a high-voltage battery system 102 or other electrical
storage device. The battery system 102 includes one or more battery
cells 103. By using an external power source that is separate from
the high-voltage battery system 102 to operate the heater system
100, the invention can keep the battery system 102 warm and
regulate the temperature of the battery system 102 reliably when
the vehicle is exposed to a cold environment.
[0014] As shown in FIG. 1, the battery heater system 100 includes a
heater 104 for warming the battery cells 103. The heater 104 itself
may have any configuration known and appreciated in the art that is
appropriate for regulating the temperature of the battery cells
103. In one embodiment, a plurality of resistive or other
thermoelectric heater elements disposed in the battery system 102
act as the heater 104. The heater 104 is coupled to the battery
cells 103. The battery cells 103 themselves can be, for example,
nickel metal hydride cells, lithium-ion cells, lead acid cells, or
any equivalent electric energy storage device. Although the
description below focuses on battery cells, the heater system may
apply to other electrical storage devices, such as
ultra-capacitors, without departing from the scope of the
invention.
[0015] The heater system 100 also includes a converter 108. In the
example shown in FIG. 1, the converter 108 is an AC/DC converter
that converts an AC voltage output from an external AC power source
110 to a lower level DC voltage output. The AC power source 110 can
be, for example, power from a wall outlet in a garage. A connector
112, such as a conventional three-pronged plug, connects the
battery heater system 100 to the AC power source 110. The output of
the AC/DC converter 108 or a suitable control signal may also be
sent to a controller 114 that controls operation of the heater 104
via one or more switches 116, such as relays, mechanical switches,
field effect transistors, etc. In one embodiment, the controller
114 also receives signals indicating a battery temperature, a key
on/off condition (e.g., whether a key is in the vehicle ignition),
and an AC/DC active signal as inputs and controls operation of the
switch 116 based on these inputs.
[0016] Alternatively, the controller 114 may be powered by, for
example, a separate low-voltage battery 120 or other alternative
power source. The low-voltage battery 120 may be, for example, a
conventional accessory battery having a nominal voltage output of
approximately 10V-15V. If the controller 114 is powered by the
low-voltage battery 120, the controller 114 can monitor the
temperature of the battery system 102 even when the battery heater
system 100 is not connected to the AC power source 110. The
controller 114 preferably draws a very small current during
operation (e.g., on the order of less than 1 mA). Moreover, by
intermittently placing the controller 114 into a sleep mode where
it draws minimal current, as will be described in greater below,
the controller 114 avoids draining the low-voltage battery 120. The
components of the heater system 100 may be connected together via
any connection structure, such as an electrical harness (not
shown).
[0017] In the example shown in FIG. 1, the controller 114 and the
switches 116 are disposed in the battery system 102, while the
AC/DC converter 108 may be placed at any location in the vehicle
outside the battery system 102. The AC/DC converter 108 tends to be
an expensive component; by placing the AC/DC converter 108 outside
of the battery system 102, the battery heater system 100 can be
marketed as a separate component as part of a vehicle heating
package and can be omitted in vehicles that do not require cold
weather assistance. Note that other components in the system (e.g.,
the controller 114 and/or the switch 116) may be placed outside the
battery system 102 as well, if desired, to further enhance
modularity by placing these components only in vehicles that
require it. FIG. 2 illustrates another embodiment of the battery
heater system 100 where both the AC/DC converter 108 and the
controller 114 are disposed outside the battery system 102.
[0018] Moreover, by placing the AC/DC converter 108 outside the
battery system 102 (e.g., near a vehicle engine), only low voltage
DC electrical lines, as opposed to high voltage AC lines, need to
be passed through a passenger compartment of the vehicle,
eliminating possible safety concerns. Keeping the AC/DC converter
108 separate from the battery system 102 makes UL certification
simpler because certification is needed only for the AC/DC
converter 108, as opposed to the entire battery system 102 if the
AC/DC converter 108 were included within the battery system
102.
[0019] Connecting the battery heater system 100 to the AC power
source 110 allows the battery system 102 to be heated for an
unlimited time period as long as the connection lasts. This creates
a distinct advantage over self-powered battery heaters, which can
heat the battery only for a finite time period. Also, the unlimited
nature of the AC power source 110 allows the battery system 102 to
be heated to a higher temperature without risking power supply
drainage, making it possible to maintain the battery temperature to
a level that allows the vehicle to start. In another embodiment,
the temperature level may be selected to ensure optimum battery
performance.
[0020] Note that if the supplemental battery is used as the
external power source, the converter 108 may be a DC/DC converter.
Of course, the converter 108 may also be omitted altogether.
[0021] FIG. 3 illustrates the battery heater system 100 coupled
with an engine block heater 200. In extremely cold regions,
vehicles are typically equipped with the engine block heater 200 to
keep an engine in good working condition in cold climates. Like the
inventive battery heater system 100, the engine block heater 200 is
designed to be connected to the AC power source 110. The modular
design of the inventive battery heater system 100 allows it to be
easily coupled to the engine block heater 200.
[0022] As shown in FIG. 3, both the battery heater system 100 and
the engine block heater 200 may be connected to the same AC power
source 110 through a single connector 112 (e.g., a single plug) as
opposed to two separate connectors. The single connector 112 is
appropriate because the battery heater system 100 and the engine
block heater 200 are usually both needed at the same time in
extremely cold climates. This streamlines the vehicle heating
package 202 and simplifies connection of the battery heater system
100 and the engine block heater 200 to the AC power source 110. The
battery heater system 100 and the engine block heater 200 may be
offered together as a modular vehicle heating package 202.
[0023] FIG. 4 is a flow diagram illustrating a control process 250
used by the controller 114 to control the battery temperature
according to one embodiment of the invention. As noted above, the
controller 114 may receive inputs corresponding to battery
temperature and a key on/off condition. The controller 114 also
checks whether it is receiving the AC/DC active signal to determine
whether the battery heater system 100 is connected to the AC power
source 110.
[0024] In the illustrated control process 250, the controller 114
assumes that the vehicle key is not in a vehicle ignition; that is,
the vehicle is in a key-off condition (block 252). The controller
114 then checks whether it is receiving the AC/DC active signal
(block 254). If not, the controller 114 assumes that the battery
heater system 100 is not connected to the AC power source 110
(block 255) and therefore maintains the heater 104 in an OFF
condition (block 256). The controller 114 then enters a sleep mode
during which it is inactive. The sleep mode may, for example,
reduce the current draw of the controller 114 (block 258). During
this sleep mode, the controller 114 waits for a selected period of
time (e.g., 2 hours) (block 260) before waking up (block 262). Note
that it may be possible to operate the heater when the vehicle is
in a key-on condition, if desired, as long as the battery heater
system 100 is connected to the AC power source 110.
[0025] If the controller 114 is receiving the AC/DC active signal
(block 254), it knows that the battery heater system 100 is
connected to the AC power source 110 (block 263). The controller
114 then checks the battery temperature (block 264) to determine
whether the battery temperature is less than a selected temperature
threshold (block 265). As noted above, the temperature threshold is
selected to ensure that the vehicle will start and/or ensure
optimum vehicle performance.
[0026] If the battery temperature is at or greater than the
temperature threshold, the controller 114 switches the heater 104
to the OFF condition if it is turned on or leaves the heater 104 in
the OFF condition if it is already turned off (block 256). The
controller 114 then enters the sleep mode (block 258) as described
above, checking the battery temperature again when it wakes up
after the selected time period.
[0027] If the battery temperature is less than the temperature
threshold (block 265), it indicates that the battery system 102
needs to be heated to reach its desired temperature. The controller
114 turns on the switch 116 to connect the heater 104 to the AC
power source 110 (block 268). At this point, the heater 104 is in
the ON condition (block 270).
[0028] The controller 114 then enters a sleep mode (block 272). In
this example, the amount of current sent to the heater 102 is low
enough so that the heater 104 can remain turned on during the sleep
mode without any danger of overheating. Alternatively, the
controller 114 may turn the switch 116 on only for a predetermined
period of time before turning it off again, without waiting for the
controller 114 to wake up out of sleep mode. Note that if the
controller 114 is powered by the AC power source 110 rather than
the low-voltage battery 120, the controller 114 can monitor the
battery temperature 114 continuously rather than only during
periodic wake-ups, further optimizing the battery system 102 power
without risking overheating.
[0029] In the example shown in FIG. 3, the controller 114 remains
in sleep mode for the selected time period (e.g., 2 hours) (block
274). The controller 114 then wakes up (block 276) and checks
whether it is receiving the AC/DC active signal (block 277). If
not, it re-enters the sleep mode (block 272). If the controller 114
is receiving the AC/DC active signal, indicating that the battery
heater system 100 is connected to the AC power source 110, the
controller 114 then measures the battery temperature (block 278).
If the battery temperature is at or below the desired temperature
threshold (block 280), the controller 114 re-enters the sleep mode
(block 272) with the switch 116 closed, thereby allowing current to
continue passing through the heater 104 and keep the heater 104 in
the ON condition. Of course, if the controller 114 is no longer
receiving the AC/DC signal at this stage, the controller 114 opens
the switch 116 to switch the heater 104 to an OFF condition.
[0030] If the battery temperature is above the temperature
threshold (block 278), it indicates that the battery system 102 is
at or above the desired optimum temperature, making it unnecessary
to continue operating the heater 104. The controller 114 therefore
opens the switch 116 to disconnect the heater 104 from the AC power
source 110 (block 282) and place the heater 104 in an OFF condition
(block 256). The controller 114 then enters the sleep mode (block
258) as described above and delays for the selected time period
before waking up to check the battery temperature again.
[0031] The inventive battery heater system therefore maintains a
desired battery temperature indefinitely by connecting the battery
heater to an AC power source rather than relying on its own
internal power source. Using the AC power source also allows the
battery heater system to work in conjunction with an engine block
heater and be powered through the engine block heater's connection
to the power source, eliminating the need for separate power source
connections. The modularity of the inventive battery heater system
also allows it to be included or omitted from a given vehicle
easily.
[0032] It should be understood that various alternatives to the
embodiments of the invention described herein may be employed in
practicing the invention. It is intended that the following claims
define the scope of the invention and that the method and apparatus
within the scope of these claims and their equivalents be covered
thereby.
* * * * *