On-line PHEV battery hysteresis effect dynamics modeling

High penetration of Plug-in Hybrid Electric Vehicles (PHEV) are expected in the near future. Battery state information is essential in protecting the PHEV battery from harmful charging/discharging, and in optimal battery management. With accurate battery relaxation effect model, the battery ν_oc (open circuit voltage) can be obtained from direct measurements on the battery´s terminal voltage and load current. The battery SoC thereby can be accurately estimated through the battery hysteresis effect model. This paper proposed a novel battery hysteresis effect dynamic model that providing a compact and accurate description to describe a family of the battery ν_oc-SoC trajectory over a large operating range and charging/discharging control strategies. The battery hysteresis loops are modeled as the responses of timeinvariant first order systems with various initial conditions. Experiment validation demonstrated that the proposed model can provide accurate descriptions to both the hysteresis major loop and the hysteresis minor loop of the battery.