Abstract
This paper presents that the fractional order Kalman filter (FOKF) method is used to estimate the state of charge (SOC) for lithium-ion battery based on the fractional order model. First, a fractional order battery model was established which can better reflect the dynamic characteristics of the battery. The fractional orders were identified by genetic algorithm. Then, compared with three other modeling methods in four aspects: maximum absolute error, maximum relative error, computational complexity and number of model parameters, it is shown that the fractional order model proposed in this paper is more accurate and reliable. The results shows that the maximum absolute error of the terminal voltage is 0.014 V under constant current discharge test. The accuracy improves 0.058 V comparing to the integer order model. Finally, the SOC was estimated through two methods. The results shows that the maximum absolute estimation error of SOC is under 0.02 by FOKF, which has higher accuracy and faster convergence speed compared with extend Kalman filter (EKF) method.
Highlights
State of charge (SOC) estimation of lithium-ion power battery is always the core of battery management system [1]
A SOC estimation method based on fractional order model and fractional order Kalman filter (FOKF) for lithium-ion battery is proposed
The maximum absolute error and maximum relative error of fractional order battery model are reduced by 0.058V and 1.8% respectively compared with integer order model
Summary
State of charge (SOC) estimation of lithium-ion power battery is always the core of battery management system [1]. INDEX TERMS Lithium-ion battery, fractional order model, state of charge estimation, Kalman filter. An accurate equivalent circuit model of lithium-ion battery is established which can effectively improve the estimation accuracy of SOC [2].
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