Keywords: batteries, supercapacitors, hybrid energy storage, power sharing, control strategy, small-signal modelling, power management, power electronics, simulation
Control and small-signal analysis of battery and supercapacitor hybrid energy storage systems
This paper is devoted to control strategies for an active battery and supercapacitor hybrid energy storage system using the master-slave control scheme, where the charging and discharging currents of the supercapacitor are dependent on that of battery and the current sharing ratio depends upon the load conditions. A small-signal model is proposed, which considers the variations in the currents of individual energy storage devices and the DC bus voltage as state variables, the variations in the power converter duty cycles as control variables, the variations in the voltages of battery and supercapacitor and the load current as external disturbances. This paper also studies the effects of the variations in the controller and filter parameters on system performance using frequency-domain analysis. Simulation results verify the proposed control strategies and the effects on the final states of the energy storage devices and also validate frequency-domain analysis.