Modeling and simulation of three phase multilevel inverter for grid connected photovoltaic systems

This paper presents a control for a three phase five-level neutral clamped inverter (NPC) for grid connected PV system. The maximum power point tracking (MPPT) is capable of extracting maximum power from the PV array connected to each DC link voltage level. The MPPT algorithm is solved by fuzzy logic controller. The fuzzy MPPT is integrated with the inverter so that a DC–DC converter is not needed and the output shows accurate and fast response. A digital PI current control algorithm is used to remain the current injected into the grid sinusoidal and to achieve high dynamic performance with low total harmonic distortion (THD). The validity of the system is verified through MATLAB/Simulink and the results are compared with three phase three-level grid connected NPC inverter in terms of THD.

► Three phase five-level inverter model for grid connected photovoltaic systems.
► Using fuzzy MPPT an optimum DC voltage is set by the inverter itself.
► Conclusion made between the five-level and three-level inverter in terms of THD.
► THD of the five-level inverter is less than that of three-level inverter.