A current stress optimization control method for photovoltaic DAB microinverters

Abstract

This paper presents a control strategy to reduce current stress and reactive power in high-efficiency single-stage double-active-bridge (DAB) photovoltaic microinverters. It uses a changing ratio of the phase shift angle between the primary and secondary bridges to the phase shift angle inside the primary bridge, instead of a fixed value, to obtain better performance. First, variable frequency control is used to linearize the phase shift function. Then, the variation pattern of the phase-shift ratio is optimized through online calculation. This method expands the zero-voltage switching (ZVS) range, lowers current stress and reactive power, and achieves 96.68% efficiency in the DAB microinverter. Experiments on a 400-W prototype confirm the effectiveness of the method.