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Modular Multilevel Inverter of A Standalone Photovoltaic System With New Modulation Techniques

Mrs.C.Thulasiyammal, Dr.S.Sutha, Mrs.Harini

This paper presents a 9-level photovoltaic (PV) inverter topology for single phase induction motor with a sinusoidal pulse width modulation (SPWM) control scheme and MPPT. Thus reducing the complexity of the system, these MPPT algorithmic methods which are based on use of perturb and observe (P & O) algorithms have been proposed with the PV panel to determine an optimum operating current for the maximum output power. Multilevel inverter as compared to single level inverter has advantages like minimum harmonic distortion and can operate on several voltage level inverters. A key component in this project is the DC to AC nine level multilevel inverter. The DC source feeding the multilevel inverter is considered to be varying in time and the switching angle is adapted to the dc source variation. This paper uses Newton Rapson algorithms to obtain switching angle offline for different dc sources value and used to determine the switching angle that correspond to the real time value of the dc sources for each phases. The modulation switching angle is updated at each cycle of the output fundamental voltage. For a multilevel inverter, switching angles at fundamental frequency are obtained by solving the selective harmonic elimination equations in such a way that the fundamental voltage is obtained as desired and certain lower order harmonics are eliminated. This paper gives details on the method in addition to simulation & experimental results