Lithium-ion battery diagnostic and prognostic techniques
First Claim
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1. A method for determining cell imbalance of a battery comprising:
- applying a charge current to a battery comprising first and second cell strings;
monitoring the battery charge current in the first and second cell strings;
sensing a first sudden current reduction in the battery charge current;
determining a first cell string charge time in the first cell string;
sensing a second sudden current reduction in the battery charge current;
determining a second cell string charge time in the second cell string;
comparing the first cell string charge time to the second cell string charge time;
determining a charge time difference between the first cell string charge time and the second cell string charge timedetermining that a cell imbalance is not present in the battery if the determined charge time difference is less than or equal to a predetermined acceptable charge time difference; and
determining that a cell imbalance is present in the battery if the determined charge time difference is greater than a predetermined acceptable charge time difference.
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Abstract
Embodiments provide a method and a system for determining cell imbalance condition of a multi-cell battery including a plurality of cell strings. To determine a cell imbalance condition, a charge current is applied to the battery and is monitored during charging. The charging time for each cell string is determined based on the monitor of the charge current. A charge time difference of any two cell strings in the battery is used to determine the cell imbalance condition by comparing with a predetermined acceptable charge time difference for the cell strings.
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11 Claims
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1. A method for determining cell imbalance of a battery comprising:
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applying a charge current to a battery comprising first and second cell strings; monitoring the battery charge current in the first and second cell strings; sensing a first sudden current reduction in the battery charge current; determining a first cell string charge time in the first cell string; sensing a second sudden current reduction in the battery charge current; determining a second cell string charge time in the second cell string; comparing the first cell string charge time to the second cell string charge time; determining a charge time difference between the first cell string charge time and the second cell string charge time determining that a cell imbalance is not present in the battery if the determined charge time difference is less than or equal to a predetermined acceptable charge time difference; and determining that a cell imbalance is present in the battery if the determined charge time difference is greater than a predetermined acceptable charge time difference. - View Dependent Claims (2, 3)
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4. A method for determining cell imbalance of a battery comprising:
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applying a charge current to a battery, wherein the battery comprises a plurality of cell strings; monitoring the battery charge current; counting a charge time for every cell of a first cell string of the plurality of cell strings based on sensing a first sudden reduction in the battery charge current, wherein the sudden current reduction indicates a charge completion of one of the first cell string; counting a charge time for every cell of a second cell string of the plurality of cell strings based on sensing a second sudden reduction in the battery charge current, wherein the sudden current reduction indicates a charge completion of one of the second cell string; determining a charge time difference between the first and second cell strings of the plurality of cell strings; and comparing the charge time difference between the first and second cell strings of the plurality of cell strings with a predetermined acceptable charge time difference for the plurality of cell strings of the battery, wherein a condition in which the charge time difference is greater than the predetermined acceptable charge time difference indicates a cell imbalance condition of the battery. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11)
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Specification