Estimating SOC and SOH of energy storage battery pack based on voltage inconsistency using reference-difference model and dual extended Kalman filter

The state-of-health (SOH) of battery cells is often determined by using a dual extended Kalman filter (DEKF) based on an equivalent circuit model (ECM). However, due to its sensitivity to initial value, this method's estimator is prone to filter divergence and requires significant computational resources, making it unsuitable for energy storage stations. This paper is proposing a novel method for determining the SOH of cells in a series-connected battery pack. The reference battery's state-of-charge (SOC) calculate firstly using the cell reference model (CRM), and then we are using the cell difference model (CDM) to calculate the internal resistance and capacity of other cells, while exploring battery health information in an innovative way by examining voltage response differences in different batteries. An experiment is conducting on a real battery data set consisting of 12 cells connected in series to verify the algorithm. The results indicate that the proposing algorithm has a lower computational cost, offers high parameter identification stability, simple parameter setting and demonstrating good performance.