Apparatus and method for estimating state of charge of battery on basis of coulomb counter

1 . An apparatus for estimating a state of charge of a battery, comprising:

a first coulomb counter STCC circuit for sampling a first charge variation ΔQ on the battery in a time comprising a number of predetermined periods, wherein the first charge variation ΔQ is calculated by adding up a battery current Im in each of the number of predetermined periods;

a compensator circuit that compensates for effects of battery aging and temperature including calculating a second charge variation ΔQ_comp in said time by compensating for the first charge variation ΔQ on the battery according to a first overpotential reference value Vds_ref, which is calculated using an internal resistance R and a second overpotential Vov of the battery obtained through an experiment on an unaged battery at room temperature;

a second coulomb counter CCE circuit for calculating a first predicted charge amount Qe by adding up the second charge variation ΔQ_comp; and

a state of charge estimator circuit for estimating the state of charge of the battery based on the first predicted charge amount Qe.

2 . The apparatus of claim 1 , wherein

the compensator circuit calculates a predicted open circuit voltage OCVe by using the first predicted charge amount Qe, and calculates the second charge variation ΔQ_comp by using the predicted open circuit voltage OCVe.

3 . The apparatus of claim 2 , wherein

the compensator circuit calculates the second charge variation ΔQ_comp by compensating for the first charge variation ΔQ so that a difference between the predicted open circuit voltage OCVe and a battery terminal voltage Vm decreases when a magnitude of the battery current Im is less than a first threshold value.

4 . The apparatus of claim 3 , wherein

the second charge variation ΔQ_comp is calculated by subtracting the predicted open circuit voltage OCVe from the battery terminal voltage Vm, then multiplying with a first constant C 1 .

5 . The apparatus of claim 4 , wherein

the first constant C 1 is predetermined on based on an internal resistance value R of the battery.

6 . The apparatus of claim 2 , wherein

the compensator circuit calculates the second charge variation ΔQ_comp by compensating for the first charge variation ΔQ so that a difference between a first overpotential predicted value Vds_e and the first overpotential reference value Vds_ref decreases when a magnitude of the battery current Im is greater than a second threshold value.

7 . The apparatus of claim 6 , wherein

the first overpotential predicted value Vds_e is calculated on a basis of a value obtained by subtracting the predicted open circuit voltage OCVe from the battery terminal voltage Vm, and the first overpotential reference value Vds_ref is calculated using a second lookup table LUT 2 comprising information about the internal resistance R and the second overpotential Vov of the battery.

8 . The apparatus of claim 7 , wherein

the information about the internal resistance R and the second overpotential Vov of the battery in the second lookup table LUT 2 is data obtained through the experiment of the unaged battery at room temperature by applying an intermittent constant current pulse at room temperature to the unaged battery.

9 . The apparatus of claim 6 , wherein

the compensator circuit calculates a charge variation compensation coefficient comp_rate, and calculates the second charge variation ΔQ_comp by multiplying the charge variation compensation coefficient comp_rate by the first charge variation ΔQ.

10 . The apparatus of claim 9 , wherein

when the first overpotential predicted value Vds_e is less than the first overpotential reference value Vds_ref, the charge variation compensation coefficient comp_rate is set to 1.

11 . The apparatus of claim 9 , wherein

when the first overpotential predicted value Vds_e is greater than the first overpotential reference value Vds_ref, as a first overpotential rate Vds_rate increases, the charge variation compensation coefficient comp_rate also increases.

12 . The apparatus of claim 11 , wherein

the first overpotential rate Vds_rate is proportional to a value obtained by dividing the first overpotential predicted value Vds_e by the first overpotential reference value Vds_ref.

13 . The apparatus of claim 9 , wherein

when the first overpotential predicted value Vds_e is greater than the first overpotential reference value Vds_ref, as a charge change rate Qm_rate increases, the charge variation compensation coefficient comp_rate increases.

14 . The apparatus of claim 13 ,

wherein the compensator circuit further includes a third coulomb counter CCM for calculating a second predicted charge amount Qm by adding up the first charge variation ΔQ; and

wherein the charge change rate Qm_rate is determined on a basis of a change rate of the second predicted charge amount Qm.

15 . A method for estimating a state of charge of a battery, wherein the method comprises:

calculating, by a first coulomb counter STCC circuit, a first charge variation ΔQ on the battery in a time comprising a number of predetermined periods, by adding up a battery current Im in each of the predetermined periods;

obtaining an internal resistance R and a second overpotential Vov of the battery through an experiment on an unaged battery at room temperature;

compensating for effects of battery aging and temperature, by a compensator circuit, including calculating a second charge variation ΔQ_comp in said time by compensating for the first charge variation ΔQ on the battery according to a first overpotential reference value Vds_ref, which is calculated using the internal resistance R and the second overpotential Vov of the battery obtained;

calculating, by a compensator circuit, a second charge variation ΔQ_comp by compensating for the first charge variation ΔQ;

calculating, by a second coulomb counter CCE circuit, a first predicted charge amount Qe by adding up the second charge variation ΔQ_comp; and

estimating, by a state of charge estimator circuit, the state of charge of the battery on a basis of the first predicted charge amount Qe.

16 . The method of claim 15 , wherein

in the calculating of the second charge variation ΔQ_comp by compensating for the first charge variation ΔQ, a predicted open circuit voltage OCVe is calculated using the first predicted charge amount Qe, and the second charge variation ΔQ_comp is calculated by compensating for the first charge variation ΔQ using the predicted open circuit voltage OCVe.

17 . The method of claim 16 , wherein

in the calculating of the second charge variation ΔQ_comp by compensating for the first charge variation ΔQ, the second charge variation ΔQ_comp is calculated by compensating for the first charge variation ΔQ so that a difference between the predicted open circuit voltage OCVe and a battery terminal voltage Vm decreases when a magnitude of the battery current Im is less than a first threshold value.

18 . The method of claim 17 , wherein

the second charge variation ΔQ_comp is calculated on the basis of a value obtained by multiplying a value, which is obtained by subtracting the predicted open circuit voltage OCVe from the battery terminal voltage Vm, by a first constant C 1 .

19 . The method of claim 15 , wherein

in the calculating of the second charge variation ΔQ_comp by compensating for the first charge variation ΔQ, the second charge variation ΔQ_comp is calculated by compensating for the first charge variation ΔQ so that a difference between a first overpotential predicted value Vds_e and a first overpotential reference value Vds_ref decreases when a magnitude of the battery current Im is greater than a second threshold value.