A super-twisting sliding mode observer for boost inverter-based hybrid photovoltaic -battery system control

This paper proposes an observer-based control scheme for a three-phase differential boost inverter in a hybrid PV-battery system. In a conventional control scheme for three-phase differential boost inverter (DBI)-based PV system, the measurements of input inductor current and voltage across output capacitors are required for obtaining the desired voltage at the load end. In a typical three-phase differential boost inverter operation, four voltage sensors and seven current sensors are required to achieve the desired AC voltage. In this paper, an observer-based strategy for elimination of these sensors without compromising power quality is reported. For estimation of boost inverter inductor current and output capacitor voltage, only DC-link capacitor voltage and the load currents are measured. A super-twisting sliding mode observer is used for estimation of the states of the boost inverter. A comparative study between the first-order sliding mode observer and super-twisting sliding mode observer is also presented. The simulation and experimental results show that the proposed observer-based control scheme works satisfactorily under various operating conditions such as sudden change of load, changes in solar insolation, and also under unbalanced load conditions.