Analysis of Dual Active Bridge based Power Electronic Transformer as a Three-phase Inverter

Dual Active Bridge (DAB) converter finds applications in the intermediate high frequency link power conversion stage of a high-power solid state transformer. In this paper, a three phase inverter based on DAB topology is proposed for grid interconnection of Photo Voltaic (PV) system. Two phase-shifted active bridges are interfaced through a single-phase high frequency transformer where the transformer leakage inductance works as the main energy transfer element. A novel switching technique is proposed to achieve dc-to-three phase ac power conversion using DAB without an intermediate dc-stage at the ac-side bridge. The inverter has advantages of high-switching frequency operation thus high power density and direct dc-to-three phase ac conversion which makes it suitable for PV applications. Steady-state analysis of the converter with the proposed switching scheme is presented along with simulation results.