AUTOMATIC METHOD FOR DETERMINING THE STATE-OF-CHARGE OF A BATTERY
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Abstract
Automatically determining state-of-charge of a battery with cells includes, for each cell, scheduling refreshment times for the cell as a function of the cell'"'"'s priority level, at times that correspond to refreshment times for the first cell, fully executing an estimation algorithm for the first cell, for at least a second cell of the set of cells, and at times other than those that correspond to refreshment times for the second cell, partially executing the estimation algorithm for the cell thereby obtaining an estimate of the second cell'"'"'s state-of-charge, and determining a state-of-charge of the battery from states-of-charge estimated for each of the cells of the battery. The estimation algorithm estimates a cell'"'"'s state-of-charge at a particular time as a function of a measured voltage and a measured current, both of which are obtained at the particular time. As a result of having scheduled refreshment times for each cell based on priority levels for the cell, a first cell from the plurality of cells has its state-of-charge estimate refreshed more frequently than a second cell from the plurality of cells when the first cell has a higher priority than the second cell.
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14 Claims
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1-7. -7. (canceled)
- 8. A method comprising automatically determining state-of-charge of a battery that comprises a set of cells that are electrically connected to one another between two electrical terminals of said battery, wherein automatically determining state-of-charge comprises for each cell from said set of cells, acquiring, at each of a plurality of times, a measured voltage between terminals of said cell and a measured current that occurs during charge or discharge of said cell, for each cell from said set of cells, calculating a voltage difference across terminals of said cell, for each cell from said set of cells, assigning a priority level, for each cell from said set of cells, scheduling refreshment times for said cell as a function of said cell'"'"'s priority level, for at least a first cell of said set of cells, and at times that correspond to refreshment times for said first cell, fully executing an estimation algorithm for said first cell, thereby refreshing an estimate of said first cell'"'"'s state-of-charge, and, for at least a second cell of said set of cells, and at times other than those that correspond to refreshment times for said second cell, partially executing said estimation algorithm for said cell thereby obtaining an estimate of said second cell'"'"'s state-of-charge, and determining a state-of-charge of said battery from states-of-charge estimated for each of said cells of said battery, wherein said cells store electrical energy, wherein said voltage difference is a difference between first and second voltage measurements obtained from across said terminals of said cell, wherein said first voltage measurement was obtained at a first time and said second voltage measurement was obtained at a second time that precedes said first time, wherein a priority level of a cell increases as a voltage difference calculated for said cell increases, and wherein said estimation algorithm estimates a state-of-charge of a cell at a particular time as a function of a measured voltage and a measured current, both of which are obtained at said particular time, whereby, as a result of having scheduled refreshment times for each cell based on priority levels for said cell, a first cell from said plurality of cells has its state-of-charge estimate refreshed more frequently than a second cell from said plurality of cells when said first cell has a higher priority than said second cell.
Specification