Detecting internal short circuits in batteries
First Claim
1. A system, comprising:
- a plurality of cells coupled in series to power a load;
a battery management system configured to;
identify a flagged cell of the plurality of cells that has an electrical parameter different from another cell of the plurality of cells;
simulate a cell model representing one of the plurality of cells;
change a value of a simulated surrogate resistor until a first voltage across the cell model equals a second voltage across the flagged cell, wherein the value of the simulated surrogate resistor is assigned as a value of an internal resistance of the flagged cell;
track an efficiency value for the flagged cell over time; and
determine whether the internal resistance of the flagged cell is due to an internal short in the flagged cell based on changes in the efficiency value.
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Accused Products
Abstract
A battery management system (BMS) described herein determines the internal resistance for a cell that may have an internal short circuit. In one aspect, the BMS monitors the voltage across each of a plurality cells that are coupled in series. If the voltage across one of the cells differs from the voltages across the other cells, the BMS can flag the cell as potentially having an internal short circuit. Once flagged, the BMS can use a simulator that stores a model cell that has similar characteristics as the cells monitored by the BMS to determine the internal resistance of the flagged cell. In one aspect, the simulator changes the value of a surrogate resistor that is parallel with the model cell until the voltage across the model cell matches the voltage of the flagged cell. The value of the surrogate resistor indicates the internal resistance of the flagged cell.
16 Citations
21 Claims
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1. A system, comprising:
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a plurality of cells coupled in series to power a load; a battery management system configured to; identify a flagged cell of the plurality of cells that has an electrical parameter different from another cell of the plurality of cells; simulate a cell model representing one of the plurality of cells; change a value of a simulated surrogate resistor until a first voltage across the cell model equals a second voltage across the flagged cell, wherein the value of the simulated surrogate resistor is assigned as a value of an internal resistance of the flagged cell; track an efficiency value for the flagged cell over time; and determine whether the internal resistance of the flagged cell is due to an internal short in the flagged cell based on changes in the efficiency value. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A computing system, comprising:
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at least one computer processor; and a memory storing a program, wherein, when executed by the computer processor, the program is configured to perform an operation comprising; identifying a flagged cell of a plurality of cells that has an electrical parameter different from another cell of the plurality of cells, wherein the plurality of cells are coupled in series to power a load; simulating a cell model representing one of the plurality of cells; changing a value of a simulated surrogate resistor until a first voltage across the cell model equals a second voltage across the flagged cell, wherein the value of the simulated surrogate resistor is assigned as a value of an internal resistance of the flagged cell; tracking an efficiency value for the flagged cell over time; and determining whether the internal resistance of the flagged cell is due to an internal short in the flagged cell based on changes in the efficiency value. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method for monitoring a plurality of cells of a battery coupled in series to power a load, the method comprising:
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identifying a flagged cell of the plurality of cells that has an electrical parameter different from another cell of the plurality of cells; simulating, using one or more processors, a cell model representing one of the plurality of cells; and changing a value of a simulated surrogate resistor until a first voltage across the cell model equals a second voltage across the flagged cell, wherein the value of the simulated surrogate resistor is assigned as a value of an internal resistance of the flagged cell; tracking an efficiency value for the flagged cell over time; and determining whether the internal resistance of the flagged cell is due to an internal short in the flagged cell based on changes in the efficiency value. - View Dependent Claims (14, 15, 16, 17)
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18. A system, comprising:
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a plurality of cells coupled in series to power a load; a battery management system configured to; identify a flagged cell of the plurality of cells that has an electrical parameter different from another cell of the plurality of cells; simulate a cell model representing one of the plurality of cells; change a value of a simulated surrogate resistor until a first voltage across the cell model equals a second voltage across the flagged cell, wherein the value of the simulated surrogate resistor is assigned as a value of an internal resistance of the flagged cell; upon determining the value of the internal resistance of the flagged cell does not satisfy a threshold, discharge the flagged cell and disconnect the flagged cell from the load; and upon determining the value of the internal resistance of the flagged cell satisfies the threshold, prevent the flagged cell from being at least one overcharged and over-discharged during at least one of a charge cycle and a discharge cycle using a spare cell selectively coupled to the flagged cell, wherein the spare cell at least one of;
sinks charge and provides charge during at least one of the charge cycle and the discharge cycle. - View Dependent Claims (19, 20, 21)
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Specification