System and method for determining and balancing state of charge among series connected electrical energy storage units
First Claim
1. A method for determining state of charge of plural series connected electrical energy storage units comprising:
- applying a non-dissipative load to a selected storage unit in a string of electrical energy storage units, resulting in an energy transfer between the selected storage unit and the string of storage units through the non-dissipative load; and
determining state of charge of the selected unit from voltage and current data of the selected storage unit resulting from the energy transfer, the state of charge of the selected unit being a fraction of a fully charged capacity of the selected unit.
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Abstract
A system and method for determining and balancing state of charge among plural series connected electrical energy storage units is provided. State of change of a selected storage unit in a string of storage units is determined by (i) applying a non-dissipative load to the selected storage unit, resulting in an energy transfer between the selected storage unit and the string of electrical energy storage units through the non-dissipative load and (ii) determining the state of charge of the selected unit from voltage and current data of the selected storage unit resulting from the energy transfer. When the state of charge of the selected unit is different than a target state of charge, energy can be transferred between the selected unit and the string of storage units, such that the state of charge of the selected unit converges toward the target state of charge.
153 Citations
42 Claims
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1. A method for determining state of charge of plural series connected electrical energy storage units comprising:
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applying a non-dissipative load to a selected storage unit in a string of electrical energy storage units, resulting in an energy transfer between the selected storage unit and the string of storage units through the non-dissipative load; and determining state of charge of the selected unit from voltage and current data of the selected storage unit resulting from the energy transfer, the state of charge of the selected unit being a fraction of a fully charged capacity of the selected unit. - View Dependent Claims (2, 3, 4)
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5. A method for balancing state of charge among plural series connected electrical energy storage units, comprising:
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applying a non-dissipative load to a selected storage unit in a string of electrical energy storage units, resulting in an energy transfer between the selected storage unit and the string of storage units through the non-dissipative load; determining state of charge of the selected unit from voltage and current data of the selected storage unit resulting from the energy transfer, the state of charge of the selected unit being a fraction of a fully charged capacity of the selected unit; and when the state of charge of the selected unit is different than a target state of charge, transferring energy between the selected unit and the string of storage units, such that the state of charge of the selected unit converges toward the target state of charge. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A system for determining state of charge of plural series connected electrical energy storage units, comprising:
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a circuit configured to apply a non-dissipative load to a selected storage unit in a string of electrical energy storage units, resulting in an energy transfer between the selected storage unit and the string of storage units; and a controller configured to determine state of charge of the selected unit from voltage and current data of the selected storage unit resulting from the energy transfer, the state of charge of the selected unit being a fraction of a fully charged capacity of the selected unit. - View Dependent Claims (23, 24, 25)
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26. A system for balancing state of charge of plural series connected electrical energy storage units, comprising:
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a circuit configured to apply a non-dissipative load to a selected storage unit in a string of electrical energy storage units, resulting in an energy transfer between the selected storage unit and the string of storage units; and a controller configured to determine state of charge of the selected unit from voltage and current data of the selected storage unit obtained during the energy transfer, the state of charge of the selected unit being a fraction of a fully charged capacity of the selected unit; and
to direct the non-dissipative load to transfer energy between the selected storage unit and the string of storage units-when the state of charge of a selected unit is different than a target state of charge such that the state of charge of the selected unit converges toward the target state of charge. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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Specification