A hybrid modulation scheme for grid-connected photovoltaic systems

Both unipolar and bipolar modulation schemes are widely used in single-phase grid-connected H-bridge inverters. This paper makes a comprehensive comparison between the aforementioned modulation strategies in aspects of basic switching action and key points, effects on operation mode, current harmonics and efficiency et al. Furthermore, a novel hybrid modulation scheme with the fusion of the unipolar and bipolar modulations is proposed in this paper. Numerical and experimental results are given to demonstrate the effectiveness and validity of the proposed method.