Estimation of state of charge of lithium ion battery using robust derivative free estimator

Abstract

This paper proposes the derivative free estimator, e.g. 1st and 2nd order of Central Difference Filter (CDF) for the estimation of State of Charge (SOC) for a Lithium-ion (Li-ion) battery. The lumped model of Li-ion battery has been instrumented here to illustrate the efficiency of the proposed method. The main problem of the Lithium-ion battery is to estimate the state of charge (SOC) accurately as the electrochemical features change with change in different parameters, such as temperature, aging, etc. These parameters implicates updating the model of the battery online. By using Central Difference Filter obviates the derivative Calculation reduces the system noise commendably, which in turn improves the estimation accuracy. In this work, the Thevenin voltage is perturbed with different level of measurement noises and SOC has been perturbed with different level of process noises, which is unavoidable in real world. CDF has been employed to the model experiments with high precision and less estimation errors.