A DAB-Based Single-Stage Three-Phase Microinverter with Grid Current Optimization

This paper proposes a dual active bridge (DAB)-based single-stage isolated three-phase microinverter, which has excellent performances in terms of efficiency, grid-connected current quality, and power density. Firstly, it adopts a "4-in-1" structure to improve the power level. The microinverter can be connected with four PV panels and realize the four-channel independent maximal power point tracking (MPPT), which can improve the power yield under partially shaded conditions. Besides, this paper proposes a space vector single phase-shifted (SVPWM-SPS) modulation strategy based on the evaluation of the modulation index, which can achieve the modulation index matching with grid-connected current. It effectively reduces the total harmonic distortion (THD) of grid current. Finally, a 2.6kW microinverter simulation model is built to verify the effectiveness of the topology and control strategy.