A Voltage Prediction Method of LiFePO_4 Batteries on Electric Vehicle During the Relaxation State after Discharging

摘要

As the electric vehicle experiences the acceleration and deceleration periods alternately, the power battery open-circuit voltage at the relaxation stte after discharging varies greatly, which brings difficulties in measuring the state of charge (SOC) and causes measurement errors. To solve this problem, a certain type of LiFePO_4 battery is taken as the research object. Based on electrochemistry and equivalent circuit theory, this research studies the relation between the open-circuit voltage at the relaxation stage after discharging of the LiFePO_4 battery in moving electric vehicle and time. Combined with system identification method, an open-circuit voltage prediction model of lithium iron phosphate batteries is established, and experiment has been carried out to verify the feasibility of the model.