Modified triple active bridge DC/AC three-phase converter with a series-resonant LC circuit on the AC-side

A novel three-port, isolated, and single-stage DC/AC three-phase converter is proposed. This converter aims at interfacing a renewable energy source, a battery pack, and the three-phase electric grid. The battery and grid ports have bidirectional power flow capability. It is comprised of three active bridges, a HF AC-link three-winding transformer, and a series-resonant LC circuit in the AC-port. In contrast to the conventional three-port series-resonant converter, this structure only includes one LC tank, which makes it more reliable and less complex. The proposed modulation consists in phase shift control under a high and fixed switching frequency. Duty ratio depending of the grid phase is introduced on the AC-side. An extra phase angle is added to control real and reactive power transfer. This topology can be considered as the superposition of a DAB DC/DC and a series-resonant DC/AC three-phase converter. As a result, the currents flowing through the transformer's windings are quasi-sinusoidal and trapezoidal waves, which permits low rms and peak current magnitudes. Steady-state analysis, design procedure, and simulation results are presented for a 1kW converter.