Minimum Loss Trajectory Modulation for Single-Stage SR-DAB Based DC/AC Converter

Single-stage DC/AC converter is increasingly adopted in photovoltaic inverters, energy storage systems and electric vehicle chargers due to its high flexibility, high efficiency and low cost. This paper introduces a minimum loss trajectory modulation strategy for single-stage SR-DAB based DC/AC converter. By establishing the precise model for the loss of the converter, the operation efficiency is optimized in a 2-dimension optimization procedure. The two operation modes of the optimized trajectory handle the heavy load and light load operating modes, respectively, which can achieve the highest converter efficiency in the 50-Hz grid cycle. Additionally, to solve the problem caused by the discontinuous modulation variables, a seamless mode switching strategy is proposed. An 500-W prototype is implemented, with rated voltage of 48-V on DC side and 220-Vrms on AC side. Experimental results validate the theoretical analysis and the practical feasibility of proposed modulation strategy.