An RLS Based Battery Modeling Method to Compensate for Recovery Effect in Battery Balancing

In battery management systems, mismatched battery cells are expected to be equalized to the same voltage level to maintain the safety and reliability of the energy storage system. However, due to battery electrochemistry characteristics, voltage of the battery cell recovers after equalization, causing the final equalization result inaccurate. To compensate for the voltage recovery effect after balancing and to improve the accuracy of balancing process, this paper proposes a model-based prediction method. A 1
^st
order battery model is established to imitate battery behaviors. Recursive-least-squares method is utilized to identify the parameters of the model to accurately fit the battery characteristic testing data. By deriving an accurate battery model, battery behavior can be better predicted. A simulation to equalize two battery cells is conducted to validate the voltage recovery prediction. The result shows that the recovery effect can be calculated in the model on a given balancing current. Therefore, it provides guidance to decide how much extended balance process is needed to compensate for the voltage recovery.