Methodology for Multiple Soc Estimation in Lithium-Ion Battery Packs based on an Adaptive Square-Root Unscented Kalman Filter

The definition of the State of Charge (SoC) at pack level represents a crucial task to be addressed in order to maximize the performances of lithium-ion battery packs while ensuring its safe operating conditions. Indeed, Soc estimation methods are currently safety oriented, thus focused on identifying the Soc of the least/most charged cells. However, this approach does not take into account for the actual pack energy utilization. This paper proposes a methodology based on an Adaptive Square-Root Unscented Kalman Filter for correctly estimating both the Soc at pack level and the one related to the least/most charged cell with a low computational cost.