The research of battery model and intelligent charging in the rail transport system

This paper introduces a third-order dynamic model for lead acid battery whose parameters vary with the state of charge (Soc), charge current and the electrolyte temperature(θ). According to the practical dynamic model, this paper also proposes two control structure for charging battery applying to constant current and constant voltage mode: i) a innovative third closed loops control strategy composed of innermost inductance current loop, inner battery current loop and outer battery voltage loop based on the DC/DC converter, ii) a novel double closed loops control strategy composed of inner current loop and outer either battery current loop under constant current mode or battery voltage loop under constant voltage mode based on the three-phase voltage-sourced PWM rectifier. Moreover, the variable proportional-integral (PI) controller and the power feed-forward control strategy are used on PWM rectifier. The simulation and experiments are carried out to prove the performance of the battery model that shows a good compromise between complexity and precision and the feasibility of the system.