Control of Grid-connected Inverter using Carrier Modulation

Abstract

Multilevel inverters are becoming prevalent due to their remarkable attributes, including their ability to withstand high voltage shocks and accommodate high capacity. As a result, they find extensive applications in grid-connected inverter systems utilizing photovoltaic (PV) panels and electric drive systems for electric motors. However, their power quality is heavily reliant on current controls and inverter modulation techniques. Conventional modulation methods typically employ fixed frequency carriers for inverter modulation, lacking inherent control signal information. In response to this challenge, this study proposes a novel modulation method for grid-connected multilevel inverters utilizing frequency and phase-modulated carriers. The study findings demonstrate the effectiveness of the proposed approach in the nominal operation, showcasing a reduction in Total Harmonic Distortion (THD) by 15.92% and a 48.5% decrease in the highest individual harmonic amplitude compared to the conventional method using the modulation of phase opposite disposition. Moreover, the switching count is also decreased by 26.37%.