State of charge quality based cell balancing control
First Claim
1. A battery control system comprising:
- a traction battery including a plurality of cells; and
at least one controller programmed to generate model parameter estimates for the cells and, in response to a magnitude of a state of charge difference between cells being greater than a predetermined value while a persistent excitation condition and an estimation convergence condition are satisfied, balance the cells according to states of charge derived from the model parameter estimates.
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Accused Products
Abstract
Hybrid-electric and pure electric vehicles include a traction battery comprised of many cells. During repeated charge and discharge cycles, the state of charge of the cells may vary from cell to cell. To optimize traction battery usage, it is desirable that the state of charge of the cells be equalized. Cell balancing can equalize the states of charge and improve battery performance. To achieve proper cell balancing, an accurate state of charge value should be known for each cell. An accurate state of charge value may be achieved when a persistent excitation condition and an estimation convergence condition are met. If the conditions are not met, active excitation of the battery may be performed to improve the chances of meeting the conditions. Cell balancing may be initiated and terminated according to state of charge values estimated when the conditions are satisfied.
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Citations
19 Claims
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1. A battery control system comprising:
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a traction battery including a plurality of cells; and at least one controller programmed to generate model parameter estimates for the cells and, in response to a magnitude of a state of charge difference between cells being greater than a predetermined value while a persistent excitation condition and an estimation convergence condition are satisfied, balance the cells according to states of charge derived from the model parameter estimates. - View Dependent Claims (2, 3, 4)
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5. A vehicle comprising:
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a traction battery including a plurality of cells; and at least one controller programmed to, in response to a magnitude of a state of charge difference between cells being greater than a predetermined value while a persistent excitation condition and an estimation convergence condition are satisfied, balance the cells according to states of charge derived from estimated cell model parameters. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12)
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13. A method of balancing cells of a traction battery by at least one controller comprising:
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initiating, after learning a first set of states of charge for the cells in response to a persistent excitation condition and an estimation convergence condition being satisfied, cell balancing based on first state of charge differences between the cells having a magnitude greater than a predetermined value; and terminating, after learning a second set of states of charge for the cells in response to the persistent excitation condition and the estimation convergence condition being satisfied, cell balancing based on second state of charge differences between the cells having a magnitude less than the predetermined value. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification