An Improved Discrete Preisach Model of Open Circuit Voltage Hysteresis for LiFePO4 Batteries

The relationship between open circuit voltage (OCV) and state of charge (SOC) is a critical characterization for batteries. The hysteresis that OCV differs between charge and discharge at the same SOC need to be carefully studied for some battery types such as NiMH and LiFePO₄. In previous research, the discrete Preisach model has proven to be effective and accurate for describing the hysteresis of LiFePO₄ batteries. However, the partitions of the Preisach triangle in the discrete Preisach model are assumed to be equal in the whole OCV range which will lead to large numbers of grids as well as much computational burden. In this paper, a non-equal partition method is proposed which can not only decrease the number of partitions in the Preisach triangle but also guarantee the model performances. The results show that the partitions number and grids number in the proposed method are only half and 25% of the previous ones respectively and the precisions of SOC output are still within 4%.