U.S. patent application number 16/715408 was filed with the patent office on 2020-04-16 for system and method for charging a battery pack.
The applicant listed for this patent is O2 Micro Inc.. Invention is credited to Guoxing LI.
Application Number | 20200119568 16/715408 |
Document ID | / |
Family ID | 60117262 |
Filed Date | 2020-04-16 |
United States Patent
Application |
20200119568 |
Kind Code |
A1 |
LI; Guoxing |
April 16, 2020 |
SYSTEM AND METHOD FOR CHARGING A BATTERY PACK
Abstract
A battery pack receives a charging current from a charger via a
power line. The battery pack includes a battery management unit and
a transmitting unit. The battery management unit is coupled to a
plurality of battery cells and is operable for acquiring data
associated with the battery pack. The transmitting unit is coupled
to the battery management unit and is operable for transmitting the
data to the charger via a power line.
Inventors: |
LI; Guoxing; (Sunnyvale,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
O2 Micro Inc. |
Santa Clara |
CA |
US |
|
|
Family ID: |
60117262 |
Appl. No.: |
16/715408 |
Filed: |
December 16, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15282318 |
Sep 30, 2016 |
10541542 |
|
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16715408 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02J 7/0021 20130101;
H02J 7/0014 20130101; H02J 7/00034 20200101; H02J 7/00036 20200101;
H02J 7/0029 20130101; H02J 7/0026 20130101; H02J 7/0068
20130101 |
International
Class: |
H02J 7/00 20060101
H02J007/00 |
Claims
1. An electronic system comprising: a charger operable for
providing a charging current via a power line to a battery pack,
wherein said charger comprises: a receiving unit, coupled to said
power line, operable for detecting a variation pattern in said
charging current and for retrieving data embodied in said variation
pattern transmitted from said battery pack via said power line; and
a charger controller, coupled to said receiving unit, operable for
controlling said charger based on said data.
2. The electronic system of claim 1, wherein said charger further
comprises: a sensor, coupled to said power line, operable for
sensing said charging current, wherein said receiving unit
comprises: a pattern database operable for storing a plurality of
pre-defined patterns, wherein said receiving unit is operable for
retrieving said data by comparing said variation pattern in said
charging current with said pre-defined patterns.
3. The electronic system of claim 1, wherein said battery pack
comprises: a battery management unit, coupled to a plurality of
battery cells, operable for acquiring said data; and a transmitting
unit, coupled to said battery management unit, operable for
transmitting said data to said charger via said power line.
4. The electronic system of claim 3, wherein said battery pack
further comprises: a signal generator, coupled to said transmitting
unit, operable for generating a control signal based on said data
to control said transmitting unit, wherein said charging current
increases if said control signal is in a first state, wherein said
charging current decreases if said control signal is in a second
state.
5. The electronic system of claim 3, wherein said transmitting unit
is operable for varying an amplitude of said charging current to
transmit said data to said charger via said power line.
6. The electronic system of claim 5, wherein said transmitting unit
comprises: a switch coupled to said power line, wherein said switch
is controlled by a control signal to vary said amplitude of said
charging current, wherein said control signal is generated based on
said data.
7. The electronic system of claim 6, wherein said charging current
increases if said switch is in a first state, wherein said charging
current decreases if said switch is in a second state.
8. The electronic system of claim 7, wherein a current is enabled
to flow from said power line through said switch if said switch is
in said first state, wherein said current is disabled if said
switch is in a second state.
9. A method for charging a battery pack, comprising: providing, by
a charger, a charging current via a power line to said battery
pack; acquiring, by a battery management unit in said battery pack,
data associated with said battery pack; transmitting, by a
transmitting unit in said battery pack, said data from said battery
pack to said charger via said power line; receiving, by said
charger, said data; and controlling, by a charger controller in
said charger, said charger based on said data.
10. The method of claim 9, further comprising: sensing, by a sensor
in said charger, said charging current; detecting, by said
receiving unit in said charger, a variation pattern in said
charging current; and retrieving, by said receiving unit in said
charger, said data embodied in said variation pattern.
11. The method of claim 10, wherein said retrieving comprises:
comparing, by said receiving unit, said variation pattern with a
plurality of pre-defined patterns to retrieve said data.
12. The method of claim 9, wherein transmitting said data to said
charger via said power line comprises: controlling a switch in said
battery pack to vary an amplitude of said charging current.
13. The method of claim 12, wherein said charging current increases
if said switch is in a first state, wherein said charging current
decreases if said switch is in a second state.
14. The method of claim 13, further comprising: enabling a current
flowing from said power line through said switch if said switch is
in said first state; and disabling said current if said switch is
in a second state.
Description
RELATED APPLICATION
[0001] This application is a divisional of the co-pending U.S.
application, Ser. No. 15/282,318, titled "System and Method for
Charging a Battery Pack," filed on Sep. 30, 2016, which is hereby
incorporated by reference in its entirety.
BACKGROUND
[0002] FIG. 1 shows a conventional charging system 100 which
includes a charger 102 for charging a battery pack 104. The battery
pack 104 includes a charging switch 112, a discharging switch 114,
and a battery management unit 116. The battery management unit 116
monitors multiple battery cells and controls the charging switch
112 and the discharging switch 114. If a safety event such as
over-voltage, over-current, over-temperature, or short-circuit
occurs in the battery pack 104 during a charging process, the
battery management unit 116 turns off the charging switch 112 to
stop charging of the battery pack 104. The charger 102 includes a
power unit 106 for providing a charging power and a charger
controller 108 for controlling the charger 102. The charger 102
also includes a charging switch 110 which is controlled by the
charger controller 108. The charging switch 110 is turned off when
the end of charge (EOC) condition is met.
[0003] In FIG. 1, the charging switch 112 is usually implemented by
a power metal-oxide-semiconductor field-effect transistor (MOSFET)
which is relatively large and expensive. Thus, it occupies more
printed circuit board (PCB) space and increases cost. It also
increases the power loss from charging and discharging because of
its drain-to-source on-state resistance (Rdson). In discharge mode,
even though the charging switch 112 does not perform any function,
it still dissipates power. Usually the discharging current is much
higher than the charging current, and so the charging switch
dissipates a significant amount of power unnecessarily in discharge
mode. Furthermore, although not shown in FIG. 1, driver circuitry
is needed to drive the charging switch 112. The driver circuitry
itself dissipates power even if the battery pack 104 is in a sleep
mode or an idle mode. Also, the charging switch 112 may be damaged
at the startup of the discharge mode, when a large discharging
current is going through an internal body diode of the charging
switch 112. This is a factor which makes the charging system 100
unreliable.
SUMMARY
[0004] Embodiments in accordance with the present invention provide
systems and methods for charging a battery pack.
[0005] In an embodiment, a battery pack receives a charging current
from a charger via a power line. The battery pack includes a
battery management unit and a transmitting unit. The battery
management unit is coupled to a plurality of battery cells and is
operable for acquiring data associated with the battery pack. The
transmitting unit is coupled to the battery management unit and is
operable for transmitting the data to the charger via a power
line.
[0006] In another embodiment, an electronic system includes a
charger operable for providing a charging current via a power line
to a battery pack. The charger includes a receiving unit coupled to
the power line and a charger controller coupled to the receiving
unit. The receiving unit is operable for receiving and detecting
patterns of variations (variation patterns) in the charging current
and for retrieving data embodied in the variation patterns
transmitted from the battery pack via the power line. The charger
controller is operable for controlling the charger based on the
data.
[0007] In yet another embodiment, a method for charging a battery
pack includes: providing a charging current from a charger via a
power line to the battery pack; acquiring data associated with the
battery pack; transmitting the data from the battery pack to the
charger via the power line; receiving the data by the charger; and
controlling the charger based on the data.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Features and advantages of embodiments of the claimed
subject matter will become apparent as the following detailed
description proceeds, and upon reference to the drawings, wherein
like numerals depict like parts, and in which:
[0009] FIG. 1 shows a conventional charging system.
[0010] FIG. 2 shows a charging system, in accordance with an
embodiment of the present invention.
[0011] FIG. 3 shows a charging system, in accordance with another
embodiment of the present invention.
[0012] FIG. 4 shows a flowchart of a method for charging a battery
pack, in accordance with an embodiment of the present
invention.
DETAILED DESCRIPTION
[0013] Reference will now be made in detail to the embodiments of
the present invention. While the invention will be described in
conjunction with these embodiments, it will be understood that they
are not intended to limit the invention to these embodiments. On
the contrary, the invention is intended to cover alternatives,
modifications and equivalents, which may be included within the
spirit and scope of the invention as defined by the appended
claims.
[0014] Furthermore, in the following detailed description of the
present invention, numerous specific details are set forth in order
to provide a thorough understanding of the present invention.
However, it will be recognized by one of ordinary skill in the art
that the present invention may be practiced without these specific
details. In other instances, well known methods, procedures,
components, and circuits have not been described in detail as not
to unnecessarily obscure aspects of the present invention.
[0015] FIG. 2 shows a charging system 200, in accordance with an
embodiment of the present invention. The charging system 200
includes a charger 202 and a battery pack 204. The charger 202 is
operable for providing a charging current via a power line 230 to
the battery pack 204.
[0016] The battery pack 204 includes a battery management unit 216,
a discharging switch 214, and a transmitting unit 220. The battery
management unit 216 is coupled to multiple battery cells (e.g., the
battery cells 241 and 242) and is operable for managing the battery
cells. For example, the battery management unit 216 is operable for
performing balance control of the battery cells during a charging
state or mode and controlling the discharging switch 214 during a
discharging state or mode. Furthermore, the battery management unit
216 is operable for monitoring the status of the battery cells and
acquiring data associated with the battery pack 204. Such data can
be, but not limited to, voltage, current, temperature, and state of
charge (SOC) of each individual battery cell or the battery pack.
Such data can also indicate various events that have occurred in
the battery pack such as over-voltage, under-voltage, over-current,
over-temperature, short-circuit, unbalanced cells, etc. The
transmitting unit 220 is coupled to the battery management unit 216
and is operable for transmitting the data to the charger 202 via
the power line 230. Receiving the data, the charger 202 is operable
for adjusting charging parameters or taking protection actions
accordingly. Adjusting the charging parameters can be, but not
limited to, adjusting the charging current, charging voltage, or
charging time, or stopping the charging output.
[0017] In an embodiment, the transmitting unit 220 includes a
switch 224 coupled to the power line 230 through a resistor 222.
The battery management unit 216 includes a signal generator 218
operable for generating a control signal 228 to control the
transmitting unit 220 based on the aforementioned data. More
specifically, the control signal 228 can have a first state, e.g.,
logic high, to turn on the switch 224 and a second state, e.g.,
logic low, to turn off the switch 224.
[0018] When the switch 224 is turned on, a current is enabled to
flow from the power line 230 through the resistor 222 and the
switch 224. Accordingly, in response to the turn-on of the switch
224, the charger 202 increases the charging current at its output
to meet the increased demand for current. When the switch 224 is
turned off, the current flowing from the power line 230 through the
resistor 222 and the switch 224 is disabled. Accordingly, the
charger 202 decreases the charging current at its output. Thus, by
controlling the switch 224, the transmitting unit 220 is operable
for varying an amplitude of the charging current, thus creating
variations in the charging current that have different patterns
(referred to hereinafter as variation patterns) based on the data.
In an embodiment, these variation patterns can be composed of
current pulses which possess a duty cycle or a frequency. The data,
which is embodied in these variation patterns, is transmitted from
the battery pack 204 to the charger 202 via the power line 230.
[0019] The charger 202 includes a power unit 206 for providing a
charging power, a charger controller 208 for controlling the
charger 202, and a charging switch 210 controlled by the charger
controller 208. The charger 202 further includes a sensor 212
coupled to the power line 230 for sensing the charging current, and
a receiving unit 221 coupled to the power line through the sensor
212. By monitoring the charging current, the receiving unit 221 is
operable for receiving and sensing or detecting the variation
patterns in the charging current and retrieving data based on the
variation patterns, as described below. In an embodiment, the
receiving unit 221 includes a pattern database 226 that stores
multiple pre-defined patterns, each corresponding to specific data.
The receiving unit 221 is operable for comparing the variation
patterns in the charging current with the pre-defined patterns to
retrieve the data transmitted from the battery pack 204 via the
power line 230. The charger controller 208 is coupled to the
receiving unit 208 and is operable for controlling the charger 202
based on the data.
[0020] In an embodiment, the pattern database 226 includes a first
pre-defined pattern T1. Data corresponding to pattern T1 indicates
that the battery pack 204 is in an over-temperature status. In
operation, if the battery pack 204 is in an over-temperature
status, then the battery management unit 216 (which monitors the
status of the battery pack as described above) opens and closes the
switch 224 in a particular pattern uniquely associated with that
status. This in turn creates a particular variation pattern in the
charging current that is also unique to that status. The receiving
unit 221 receives (senses or detects) the variation pattern in the
charging current and matches that pattern to the first pre-defined
pattern T1. In this manner, data corresponding to pattern T1 is
retrieved and is used to identify the presence of the
over-temperature status. Accordingly, the charger controller 208
turns off the charging switch 210 to stop the charging.
[0021] In a second embodiment, the pattern database 226 includes a
second pre-defined pattern T2. Data corresponding to pattern T2
indicates that the temperature of the battery pack 204 is above a
threshold. In operation, if the temperature of the battery pack 204
is over a threshold, then the battery management unit 216 opens and
closes the switch 224 in a particular pattern uniquely associated
with that status. This in turn creates a particular variation
pattern in the charging current that is also unique to that status.
The receiving unit 221 receives (senses or detects) the variation
pattern in the charging current and matches that pattern to the
second pre-defined pattern T2. In this manner, data corresponding
to pattern T2 is retrieved and is used to identify that the
temperature of the battery pack is above a threshold. Accordingly,
the charger controller 208 adjusts the charging current to a lower
level in order to decrease the battery pack temperature.
[0022] In a third embodiment, the pattern database 226 includes a
third pre-defined pattern T3. Data corresponding to pattern T3
indicates that the temperature of the battery pack 204 is below a
threshold. In operation, if the temperature of the battery pack 204
is below a threshold, then the battery management unit 216 opens
and closes the switch 224 in a particular pattern uniquely
associated with that status. This in turn creates a particular
variation pattern in the charging current that is also unique to
that status. The receiving unit 221 receives the (senses or
detects) variation pattern in the charging current and matches that
pattern to the third pre-defined pattern T3. In this manner, data
corresponding to pattern T3 is retrieved and is used to identify
that the temperature of the battery pack is below a threshold.
Accordingly, the charger controller 208 adjusts the charging
current to a higher level to speed up the charging process.
[0023] Other statuses, such as those mentioned above, can be
identified in a similar manner, and the various embodiments just
described can be combined.
[0024] As described above, utilizing the transmitting unit 220, the
battery pack 204 is operable for transmitting data to the charger
202 via the power line 230. Utilizing the receiving unit 221, the
charger 202 is operable for retrieving the data and performing
corresponding actions to control the charging process.
Advantageously, a simple and low-cost solution to communicate
between the charger and the battery is provided. Compared with the
conventional charging system 100 in FIG. 1, the expensive and
large-size charging switch in the battery pack can be eliminated.
With the communication between the charger and the battery, the
battery pack can be fully and safely charged, and the power loss is
reduced. For example, if both charging switch 112 and discharging
switch 114 in FIG. 1 have the same drain-to-source on-state
resistance Rdson, the total power loss will be 2*I.sup.2*Rdson,
where I is the current flowing through the charging switch 112 and
the discharging switch 114. According to the present invention, the
conventional charging switch in the battery pack is eliminated
while its function is taken over by the charging switch 210 in the
charger, and thus the total power loss in the battery pack side can
be reduced by half.
[0025] FIG. 3 shows a charging system 300, in accordance with an
embodiment of the present invention. Elements labeled the same as
in FIG. 2 have similar functions.
[0026] The charging system 300 includes a charger 302 for charging
a battery pack 304. In addition to the power line 230, the charging
system 300 includes a communication line 330 coupled between the
charger 302 and the battery pack 304. For example, the
communication line 330 can be a data line in a universal serial bus
(USB) cable. In the charger 302, the charger controller 208 is
coupled to the communication line 330. The battery pack 304
includes a temperature sensor, e.g., a negative temperature
coefficient thermistor 312 coupled to the communication line 330. A
resistance of the thermistor 312 and a voltage across the
thermistor 312 change with the temperature. In an embodiment, the
thermistor 312 senses temperature and transmits the temperature
data to the charger 302 via the communication line 330 by adjusting
a voltage at the communication line 330. The charger 302 obtains
the temperature data by monitoring the voltage at the communication
line 330. In another embodiment, the temperature data is converted
to a variation pattern in the charging current by the transmitting
unit 220 and is transmitted to the charger 302 via the power line
230. The charger 302 obtains the temperature data by monitoring the
variation of the charging current over the power line 230.
[0027] FIG. 4 shows a flowchart 400 of a method for charging a
battery pack, in accordance with an embodiment of the present
invention. FIG. 4 is described in combination with FIG. 2.
[0028] In block 402, a charger 202 provides a charging current via
a power line 230 to a battery pack 204.
[0029] In block 404, a battery management unit 216 in the battery
pack 204 acquires data associated with the battery pack 404.
[0030] In block 406, the data is transmitted by a transmitting unit
220 in the battery pack 204 to the charger 202 via the power line
230. In an embodiment, in order to transmit the data, a switch 224
in the battery pack 204 is controlled to vary an amplitude of the
charging current and to create a variation pattern in the charging
current based on the data.
[0031] In block 408, the charger 202 receives the data. More
specifically, a sensor 212 in the charger 202 senses the charging
current. A receiving unit 221 in the charger 202 receives and
detects the variation pattern in the charging current and compares
the variation pattern with pre-defined patterns to retrieve the
data.
[0032] In block 410, a charger controller 208 in the charger 202
controls the charger 202 based on the data.
[0033] While the foregoing description and drawings represent
embodiments of the present invention, it will be understood that
various additions, modifications and substitutions may be made
therein without departing from the spirit and scope of the
principles of the present invention as defined in the accompanying
claims. One skilled in the art will appreciate that the invention
may be used with many modifications of form, structure,
arrangement, proportions, materials, elements, and components and
otherwise, used in the practice of the invention, which are
particularly adapted to specific environments and operative
requirements without departing from the principles of the present
invention. The presently disclosed embodiments are therefore to be
considered in all respects as illustrative and not restrictive, the
scope of the invention being indicated by the appended claims and
their legal equivalents, and not limited to the foregoing
description.
* * * * *