Highly precise determination of the state of charge of vehicular battery

ABSTRACT

An intelligent battery sensor is an important component for vehicular energy management, and the precision of online estimation of the state of charge determines sensor’s performance. A simple equivalent circuit was employed to describe the dynamic properties of vehicle lead-acid batteries. A model is reported to estimate the state of charge using the approximately linear relationship of open circuit voltage with this parameter. A time-varying circuit of the model was prepared and an identification model was derived to improve the accuracy. A method that employed a cascaded combination of double improved extended Kalman filters is reported and employed in a demonstration intelligent battery sensor. This approach has higher precision and speed in estimating the state of charge compared to previous protocols.

KEYWORDS:

• Battery circuit model
• dual extended Kalman filter
• estimation of state of charge
• lead-acid battery