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US 2014/0350875 A1Published application
Relaxation model in real-time estimation of state-of-charge in lithium polymer batteries
OwnerScott Allen Mullin, Albert Aumentado +1inventors
InventorsScott Allen Mullin, Albert Aumentado, Mohit Singh
Life of this patent
Estimating the term…
Abstract
Relaxation time constants give valuable information about a lithium polymer battery cell's state-of-charge. Moreover, determination of these time constants can be performed in real time by fitting exponential functions to transient voltage or current patterns.
Claims10
A method of determining the state of charge for a battery cell comprising:
- measuring voltage and current as a function of time while the battery cell is operating;
- recording in a memory location the voltage as a function of time over periods in which the current, expressed in terms of C-rate, is stable to within +/−0.01 C;
- fitting, using a computer processor, the recorded voltage as a function of time to a pre-defined function that has three or more fit parameters, wherein the three or more fit parameters are selected to generate a fit of the recorded voltage as a function of time;
- and
- determining the state of charge of the battery cell by comparing, using a computer processor, the three or more fit parameters to a previously-populated look-up table in a memory location, wherein the look-up table correlates the fit parameters to state-of-charge values.
2 more elements
A computer-readable medium comprising code which, upon execution by a computer processor implements a method, the method comprising:
- measuring voltage and current as a function of time while the battery cell is operating;
- recording in a memory location the voltage as a function of time over periods in which the current, expressed in terms of C-rate, is stable to within +/−0.01 C;
- fitting, using a computer processor, the recorded voltage as a function of time to a pre-defined function that has three or more fit parameters, wherein the three or more fit parameters are selected to generate a fit of the recorded voltage as a function of time;
- and
- determining the state of charge of the battery cell by comparing, using a computer processor, the three or more fit parameters to a previously-populated look-up table in a memory location, wherein the look-up table correlates the fit parameters to state-of-charge values.
2 more elements
Dependencies are inferred from the claim text.