AC-AC hybrid dual active bridge converter for solid state transformer

This paper presents an alternative for energy processing in smart grids, connected through a high frequency link. It investigates the application of an ac-ac converter with high frequency transformer. The proposed converter consists of a full-bridge and a half-bridge connected through a high-frequency link. To ensure bi-directional power flow, four-quadrant switch cells are used. The alternative proposed has advantages when applied in smart distribution grids: e.g. bidirectional power flow, low cost, high efficiency, small size, allows to make leakage inductance of the transformer an energy transference device, reduced number of passive components, high power density and high reliability. The modulation adopted in this case is phase-shift modulation (PSM) and the power transferred between the bridges can be controlled through the phase angle between switches command. One design example is presented and some simulation and practical results are used to prove the theoretical analysis and to support the conclusions.