Dual-Mode Soft-Transition Control for Single-Phase Grid-Connected Photovoltaic Inverters

Single-phase grid-connected inverters for photovoltaic power generation have been strongly analysed for improvement. Dual-mode control for two-stage inverters makes it possible to improve the efficiency by alternating between switching the dc/dc boost and the dc/ac buck stages, depending on the grid voltage value. However, according to the literature, the transition from one mode to the other is abrupt, which harms the grid current quality. This paper proposes a dual-mode control method which achieves high efficiency and a soft transition in the grid current. Applying suitable feed-forward compensations, this control method improves the grid current quality, as demonstrated by the presented simulation results.