Battery state-of-charge estimation for hybrid and electric vehicles using extended kalman filter techniques
View Patent ↗Adaptive estimation techniques to create a battery state estimator to estimate power capabilities of the battery pack in a vehicle. The estimator adaptively updates circuit model parameters used to calculate the voltage states of the ECM of a battery pack. The adaptive estimation techniques may also be used to calculate a solid-state diffusion voltage effects within the battery pack. The adaptive estimator is used to increase robustness of the calculation to sensor noise, modeling error, and battery pack degradation.
1. A method for managing a battery in a vehicle, wherein the vehicle includes a battery management controller including a processor and a computer-readable medium containing computer readable and executable instructions, the method comprising:
in response to detecting a predetermined state in the vehicle:
sensing, with at least one sensor electrically coupled to the battery, a voltage and a current of the battery;
executing, in the battery management controller, an instruction to cause the battery management controller to:
determine a solid-state diffusion voltage effect employing a solid-state diffusion effects model based upon the sensed voltage of the battery,
determine an observed output by subtracting the solid-state diffusion voltage effect from the sensed voltage of the battery,
determine double-layer voltage and circuit parameter estimates and an associated covariance based upon the observed output employing an adaptive estimation technique,
determine a Kalman gain based upon the double-layer voltage and circuit parameter estimates and the associated covariance, and simultaneously calculate a modeled output of terminal voltage based upon the double-layer voltage and the circuit parameter estimates,
sense, with the at least one sensor electrically coupled to the battery, a voltage and a current of the battery,
determine an output model error based upon the sensed voltage of the battery,
update the double-layer voltage and the circuit parameter estimates based upon the Kalman gain and the output model error,
determine an open-circuit voltage of the battery based upon the double-layer voltage, and
determine a state of charge for the battery based upon the open-circuit voltage; and
managing the power output of the battery using the state of charge for the battery.
2. The method of claim 1 , wherein a start-up temperature and a shut-down temperature are recorded in the computer-readable medium and used to vary the solid-state diffusion effects model upon start-up.
3. The method of claim 1 , wherein an off-time is recorded in the computer-readable medium and used to compensate the solid-state diffusion effects model upon start-up.
4. The method of claim 1 , wherein the solid-state diffusion effects model comprises an equivalent circuit of the battery, at least one state of the battery and a diffusion circuit element of the battery.
5. The method of claim 1 , wherein the adaptive estimation technique comprises an extended Kalman filter.