Various Strategies Comparison of NPC Inverter Current Control Connected to the Grid for Photovoltaic System

Multilevel inverters offer advantages in terms of the output waveform quality due to the increased number of levels used in the output voltage modulation such us three level NPC inverter. The output current and voltage is the same for NPC and half bridge but the difference is the way to generate the signal and its current control. This paper presents a comparative study of four current control techniques such as hysteresis current controller, Predictive current controller, Proportional Integral controller and Periodic sampling current controller. Comparison is done based on switching frequency, harmonic distortion and dynamic response of each method. Simulation of these controllers is done in PSIM environment. Waveforms of output current injected into the grid, THD etc are shown for different current controllers.