The invention discloses an SOC
estimation method based on an adaptive double extended Kalman filtering method. The SOC
estimation method comprises the following steps: firstly, establishing a second-order RC
equivalent circuit model of a
lithium battery; then, determining open-circuit
voltage and battery
equivalent model parameters at different SOC (
state of charge) positions of the
lithium battery through a pulse charging and discharging experiment; obtaining a function relationship between the open-circuit
voltage and the SOC and relationships between other
model parameters and different SOCs, the other
model parameters including ohmic
internal resistance, electrochemical polarization resistance, electrochemical polarization
capacitance, concentration difference polarization resistance and concentration difference polarization
capacitance values; establishing a
state space equation taking the SOC and
polarization voltage as state variables and a
state space equation taking the ohmicinternal resistance as a
state variable; and finally, performing iterative computation to obtain the SOC value of the
lithium battery in real time. According to the method, the problem of unknown
noise statistical characteristics in the prior art is solved, and meanwhile, the ohmic
internal resistance of the battery is estimated by using the
Kalman filtering algorithm, so that the model precisionis improved.