Abstract—This paper presents a single-phase five-level inverter topology for grid-connected PV systems with a novel Pulse Width-Modulated (PWM) control scheme. Two reference signals identical to each other with an offset equivalent to the amplitude of the triangular carrier signal were used to generate PWM signals for the switches. A proportional-integral current control algorithm is implemented in MATLAB/SIMULINK to keep the current injected into the grid sinusoidal and to have high dynamic performance with rapidly changing atmospheric conditions. The inverter offers much less total harmonic distortion and can operate at near-unity power factor. A Proportional Integral (PI) current control algorithm is implemented to optimize the performance of the inverter. Simulation results indicate that the Total Harmonic Distortion (THD) of the five level inverter is much lesser than that of the conventional three-level inverter. Further, both the grid voltages and grid current are in phase at near-unity power factor.

Index Terms—PWM inverter, Grid connected, Photovoltaic system, Proportional integral, Current control, PID control

Cite: R Narendra Rao and V Ganesh, "FIVE LEVEL INVERTER FOR OFF GRID CONNECTED PV SYSTEM EMPLOYING PI AND PID CONTROLLERS," International Journal of Electrical and Electronic Engineering & Telecommunications, Vol. 3, No. 2, pp. 69-79, April 2014.