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 article 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-D 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. In addition, 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.