State of charge algorithm for lead-acid battery in a hybrid electric vehicle
First Claim
1. A method of determining the state of charge of a battery comprising:
- integrating the charge going in and out of the battery to determine a current based state of charge measurement;
compensating the current based state of charge measurement using a Peukert factor; and
measuring the open circuit voltage to determine a voltage based state of charge measurement; and
compensating the current based state of charge measurement based on the voltage based state of charge measurement.
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Abstract
A method and apparatus for determining the state of charge of a lead-acid battery. The present invention includes steps to determine a current-based state of charge while accounting for such factors as current, temperature, charge efficiency, parasitic losses and self-discharge. The present invention is capable of measuring and/or calculating the open circuit voltage during and after operation to determine a voltage-based state of charge while compensating the open circuit voltage for its transient behavior and accounting for the voltage shift caused by charge events. The correlation of the open circuit voltage to the state of charge is dependent on the battery'"'"'s mode of operation. The present invention is adaptive to battery aging by updating the battery resistance, correcting coulomb errors, and accounting for capacity degradation while in operation.
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Citations
17 Claims
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1. A method of determining the state of charge of a battery comprising:
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integrating the charge going in and out of the battery to determine a current based state of charge measurement;
compensating the current based state of charge measurement using a Peukert factor; and
measuring the open circuit voltage to determine a voltage based state of charge measurement; and
compensating the current based state of charge measurement based on the voltage based state of charge measurement. - View Dependent Claims (2, 3, 4, 5)
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6. A method of determining the state of charge of a lead acid battery comprising:
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integrating coulombs charging and discharging the battery to determine a first state of charge measurement;
adjusting the first state of charge measurement using a Peukert factor;
measuring the open circuit voltage to determine a second state of charge measurement;
determining the operation of the battery and using the first state of charge or second state of charge measurement as the actual state of charge measurement based on the operation of the battery. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A method of determining the state of charge of a lead acid battery operating in a vehicle, the method comprising:
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integrating current charging and discharging the battery to determine a first state of charge measurement;
adjusting the first state of charge measurement using a Peukert relationship;
measuring the open circuit voltage to determine a second state of charge measurement by using a set of data points mapping open circuit voltage to state of charge for the battery; and
determining which of the first state of charge measurement or the second state of charge measurement more accurately represents the actual state of charge of the battery. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification