A novel pulse width modulation for grid-connected multilevel inverter Available to Purchase

This paper presents a single-phase five-level grid-connected photovoltaic inverter with a novel dual reference modulation technique. Two reference signals identical to each other with an offset equivalent to the amplitude of the triangular carrier signal were used to generate pulse width modulation (PWM) signals. The inverter consists of a full-bridge inverter and an auxiliary circuit comprising of four diodes and a switch. The inverter produces output voltage in five levels: 0, $+1/2Vdc$⁠, $Vdc$⁠, $−1/2Vdc$⁠, and $−Vdc$⁠. A digital proportional-integral (PI) current control algorithm is implemented in DSP TMS320F2812 to keep the current injected into the grid sinusoidal and to have high dynamic performance with low total harmonic distortion (THD). The validity of the proposed inverter is verified through simulation and is implemented in a prototype. The experimental results are compared to conventional single-phase three-level grid-connected pulse width modulation (PWM) inverter in terms of THD.