Battery management system and driving method thereof
The present invention relates to a battery management system and method. In some embodiments the battery management system includes a sensing unit and a micro controller unit (MCU). The sensing unit measures the current, the voltage and the temperature of a battery. The MCU receives the voltages, the currents, and the temperatures, calculates an estimated cell voltage, by applying a pack voltage sensing error and the cell voltage deviation to the cell voltages, and calculates an estimated cell resistance, by adding a pack assembly resistance to an internal resistance of the cell, and calculates an pack output of the battery by using the estimated cell voltage and the estimated cell resistance.
1. A battery management system that manages a battery comprising at least one pack comprising a plurality of cells, the system comprising:
a sensing unit to measure a voltage, a current, and a temperature of each of the cells; and
a micro controller unit (MCU) to receive the voltage, the current, and the temperature of each cell, to calculate an estimated cell voltage, by applying a pack voltage sensing error and a cell voltage deviation to each cell voltage, to calculate an estimated cell resistance, by adding a pack assembly resistance to an internal resistance of the cell, and to calculate a pack output, by using the estimated cell voltage and the estimated cell resistance,
wherein the pack assembly resistance is a resistance of elements of the pack other than the cells.
2. The battery management system of claim 1 , wherein the MCU is to calculate the estimated cell voltage by adding the pack voltage sensing error, a cell voltage deviation, and the cell voltage, and to calculate a charged cell current by using a voltage difference between a fully charged cell voltage and the first estimated cell voltage, and the estimated cell resistance.
3. The battery management system of claim 2 , wherein the MCU is to calculate the charged pack output by using the equation:
P
c
=
[
4.2
-
(
V
cell
+
V
acc
+
V
cell_var
)
R
cell
×
1000
×
4.2
]
×
the
number
of
cells
wherein, Vcell is the cell voltage, Vacc is the pack voltage sensing error, Vcell 13 var is the cell voltage deviation, and Rcell is the estimated cell resistance.
4. The battery management system of claim 1 , wherein,
the MCU is to calculate the difference between the cell voltage, the pack voltage sensing error, and the cell voltage deviation that are produced while discharging the battery, to calculate a second estimated cell voltage, and to calculate the discharging cell current by using a voltage difference between the second estimated cell voltage and the fully charged cell voltage and an estimated cell resistance.
5. The battery management system of claim 4 , wherein the MCU is to calculate a discharging pack output of the battery using the equation:
P
d
=
[
(
V
cell
-
V
acc
-
V
cell_var
)
-
2.8
R
cell
×
1000
×
2.8
]
×
the
number
of
cells
wherein Vcell is the cell voltage, Vacc is the pack voltage sensing error, Vcell 13 var is the cell voltage deviation, and Rcell is the estimated cell resistance.
6. The battery management system of claim 1 , wherein the MCU further comprises a data storage unit to store data from the sensing unit.
7. The battery management system of claim 1 wherein the MCU further comprises a pack modeling unit to calculate the pack output.
8. A battery management method for managing a battery comprising at least one pack comprising a plurality of cells, the method comprising:
calculating by using a micro controller unit (MCU) an estimated cell voltage by using a pack voltage sensing error, a cell voltage deviation, and a cell voltage;
calculating an estimated cell resistance by adding a pack assembly resistance to an internal resistance of the cell; and
calculating a pack output by using the estimated cell voltage, the estimated cell resistance, and one of a fully charged cell voltage and fully discharged cell voltage,
wherein the pack assembly resistance is a resistance of elements of the pack other than the cells.
9. The method of claim 8 , wherein the calculating of the estimated cell voltage comprises, adding the pack voltage sensing error, the cell voltage deviation, and the cell voltage, wherein the pack voltage sensing error, the cell voltage, and the cell voltage deviation are detected while the pack is charging.
10. The method of claim 9 , wherein the calculating of the battery output comprises, calculating a charging cell current by using a difference between the fully charged cell voltage and the estimated cell voltage, divided by the estimated cell resistance.
11. The method of claim 9 , wherein the calculating of the pack output comprises using the following equation:
P
c
=
[
4.2
-
(
V
cell
+
V
acc
+
V
cell_var
)
R
cell
×
1000
×
4.2
]
×
the
number
of
cells
wherein Vcell is the cell voltage, Vacc is the pack voltage sensing error, Vcell_var is the cell voltage deviation, and Rcell is the estimated cell resistance.
12. The method of claim 8 , wherein the calculating of an estimated cell voltage comprises calculating the difference between the cell voltage the pack voltage sensing error, and the cell voltage deviation, wherein, the cell voltage, the pack voltage sensing error, and the cell voltage deviation are detected while the pack is discharging.
13. The method of claim 12 , wherein the calculating of the pack output comprises calculating the discharging cell current by using a voltage difference between the second estimated cell voltage and the fully discharged cell voltage, divided by an estimated cell resistance.
14. The method of claim 12 , wherein the calculating of the pack output comprises calculating the discharging pack output of the battery using the following equation:
P
d
=
[
(
V
cell
-
V
acc
-
V
cell_var
)
-
2.8
R
cell
×
1000
×
2.8
]
×
the
number
of
cells
wherein, Vcell is the cell voltage, Vacc is the pack voltage sensing error, Vcell_var is the cell voltage deviation, and Rcell is the estimated cell resistance.
15. The method of claim 8 , wherein the cell voltage is an average voltage of the plurality of cells.
16. A battery management method, for managing a battery pack comprising a plurality of cells, the method comprising:
calculating by using a micro controller unit (MCU) an estimated cell voltage of the pack;
calculating an estimated cell resistance of the pack; and
calculating a pack output of the pack by using an estimated cell voltage of the plurality of cells, an estimated cell resistance of the plurality of cells, and one oft the fully charged cell voltage of the pack and the fully discharged cell voltage of the pack,
wherein the calculating of the estimated cell voltage comprises detecting the cell voltage, the pack voltage sensing error, and the cell voltage deviation of the pack, while the pack is discharging.
17. The method of claim 16 , wherein the calculating an estimated cell voltage comprises, adding a pack assembly resistance of the pack to an internal resistance of the plurality of cells of the pack,
wherein the pack assembly resistance is a resistance of elements of the pack other than the cells.
18. The battery of claim 16 , wherein the calculating a pack output comprises, using the following formula:
P
c
=
[
4.2
-
(
V
cell
+
V
acc
+
V
cell_var
)
R
cell
×
1000
×
4.2
]
×
the
number
of
cells
wherein Vcell is the cell voltage, Vacc is the pack voltage sensing error, Vcell_var is the cell voltage deviation, and Rcell is the estimated cell resistance.
19. The method of claim 16 , wherein the calculating an estimated cell voltage comprises detecting the cell voltage, the pack voltage sensing error, and the cell voltage deviation, of the pack, while the pack is charging.
20. The method of claim 16 , wherein the calculating a pack output comprises using the following formula:
P
d
=
[
(
V
cell
-
V
acc
-
V
cell_var
)
-
2.8
R
cell
×
1000
×
2.8
]
×
the
number
of
cells
wherein, Vcell is the cell voltage, Vacc is the pack voltage sensing error, Vcell_var is the cell voltage deviation, and Rcell is the estimated cell resistance.