| CPC H02J 7/0049 (2020.01) [G01R 31/367 (2019.01); G01R 31/382 (2019.01); G01R 31/392 (2019.01); G01R 31/396 (2019.01); H02J 7/0016 (2013.01); H02J 7/005 (2020.01); H02J 7/007182 (2020.01)] | 16 Claims |
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1. A method for estimating a state of charge (SOC) of a battery pack in use, performed by a battery management system that comprises a memory and a processor, wherein the battery pack comprises a first cell whose state of charge-open circuit voltage (SOC-OCV) curve does not have a plateau and a second cell whose SOC-OCV curve has at least one plateau, and the first cell is serially connected to the second cell, wherein the method comprises:
determining a capacity variation of the battery pack based on a SOC variation of the first cell in comparison with an initial SOC of the first cell and based on a nominal capacity of the first cell;
obtaining an equalization capacity of the first cell and an equalization capacity of the second cell, each equalization capacity being obtained by calculating an integral of an equalization current with respect to an equalization time;
estimating a SOC of the second cell based on the capacity variation of the battery pack, the nominal capacity of the first cell, the equalization capacity of the first cell, the equalization capacity of the second cell, and an initial SOC of the second cell;
determining the SOC of the battery pack based on the SOC of the second cell;
when the first cell is to be fully discharged first before the second cell, performing an equalization discharge on the second cell to ensure that the second cell is fully discharged first; and
when the first cell is to be fully charged first before the second cell, performing an equalization discharge on the first cell to ensure that the second cell is fully charged first.
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