Multistring seven-level inverter for standalone photovoltaic systems

Abstract

This paper presents a single phase standalone two stage photovoltaic (PV) system using seven level inverter. The first stage of conversion in the proposed system uses basic boost converter which ensure Maximum power point tracking(MPPT) and inverter dc bus voltage regulation. A hybridised seven level inverter with less number of components is used as the second stage of conversion that provides ac voltage of required magnitude and frequency. The modulation scheme used for the inverter is level shifted multi carrier pulse width modulation (LS-PWM). A central controller is designed to maintain the dc bus voltages within the reference band irrespective of variations in solar irradiance and load demand. The validity of proposed inverter in PV system is verified through simulation.