Coordination control for supercapacitor charge and discharge in PV energy storage system based on EL and backstepping

To realize the constant voltage charging of photovoltaic(PV) supercapacitor energy storage system and the control target of the constant voltage power supply, a control method which combines the signal control strategy and energy control strategy is used to control the supercapacitor charging and discharging processes. From energy control strategy, the Euler - Lagrange (EL) models of the supercapacitor charging and discharging circuits are respectively established. The damping matrix injected and expected by the system during charge and discharge process of supercapacitor are given, and the equilibrium of the system has been determined, the EL controller of the system is calculated. From signal control strategy, backstepping controller of the system is calculated. Coordinated controller is calculated through coordination function. The simulation results show that the coordinated control method not only can realize the constant voltage charging of the super capacitor and the constant voltage discharge of the supercapacitor to the load but also save the energy of system, and the supercapacitor constant voltage discharge system has strong robustness.