Implementation of Microcontroller Based PWM Scheme for PV Multilevel Inverter

This paper presents a single phase five level photovoltaic (PV) 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 digital Proportional-Integral derivative (PID) current control algorithm is implemented in MICROCONTROLLER PIC16C7F88 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-unit power factor. The proposed system is verified through simulation and is implemented in a prototype. Experimental results are compared with the conventional single phase three level grid connected PWM inverter.