Optimizing efficiency and performance for single-phase photovoltaic inverter with dual-half bridge converter

An isolated photovoltaic converter for residential use and its control strategies are investigated in this paper. This technique provides galvanic isolation and simplified control while still meeting high conversion efficiencies and wide input voltage range requirements. Through designing the equivalent resonant capacitor and inductor, zero-voltage switching (ZVS) and zero-current switching (ZCS) are realized. Efficiency is dramatically increased by reducing the circulating energy during each switching cycle. In order to analyze the resonant converter and achieve better performance, an optimal state-trajectory control is investigated and implemented. To significantly reduce the voltage error and achieve a better transient response for the grid-tied mode operation, the proposed direct-quadrature (D-Q) frame control is used instead of a normal PID control for the inverter. Simulation and experimental results reported in this paper verify the functionality of the proposed topology and the respective controller for optimizing efficiency and performance.