Bi-directional DCM DAB inverter for SST applications

Generally, conventional single phase solid state transformer (SST) topologies includes three stage conversions. In the first stage, AC/DC conversion accomplished for transforming high voltage AC (HVAC) to high voltage DC (HVDC). From HVDC, low voltage DC is obtained at the second stage, and low voltage AC is formed at the third stage. Three stage conversions are suitable for connecting renewable energy sources through low voltage DC (LVDC). However, all of the stages are switched at high switching frequency. Hence, this situation may bring high switching losses, high control complexity and lower efficiency. In this paper, we proposed bi-directional current source discontinues conduction mode (DCM) Dual Active Bridge (DAB) inverter. In the proposed inverter, HVDC is transformed to LVAC in one high frequency switching stage. Hence, it eliminates the third stage of three stage conventional SST. On the other hand, renewable energy sources can be connected to the proposed converter through LVAC bus. In this paper, the analysis of the proposed inverter is presented, and simulation results are given under resistive and inductive loads for validating the proposed inverter.