Grid Connected Nine-Level Inverter for Photovoltaic Applications

This paper presents single-phase nine-level grid connected inverter using a photovoltaic system as an input DC source. This inverter is using a Pulse Width Modulation (PWM) in which four identical reference signal shifted in levels are being compared with high frequency triangular carrier signal. This inverter is capable to attain nine levels (V-dc, 3V(dc)/4, V-dc/2, V-dc/4, 0, -V-dc/4, -V-dc/2, -3V(dc)/4, -V-dc) in output voltage. This grid connected inverter is being able to transfer sinusoidal current in to the grid using a control scheme with maintaining constant DC link voltage. Simulations are done in MATLAB, Simulink and results obtained are shown.