Balancing control based on states of charge and states of health estimates at cell level

Abstract

Optimized balancing strategies are required to manage in the long-term the imbalances in batteries with cells strings. They are usually based on voltage monitoring and/or instantaneous estimates of the cells states of charge and aim to equalize the states of the cells at the end of a charge. The present paper proposes to take benefit from estimates of the cells capacity disparities to optimize these strategies. It allows the battery management system to predict the balancing needs in order that each of the cells reaches its individualized objective. After the presentation of the algorithm principle, a focus is done on passive balancing systems. They are implemented for numeric simulations with a Li-ion battery.