Single Stage Isolated Bidirectional DC/AC Three-phase Converter with a Series-resonant Circuit for V2G

An isolated bidirectional series-resonant DC/AC three-phase converter with a single-stage power conversion for V2G applications is proposed in this paper. It is comprised of two active bridges, a series-resonant LC tank and a HF transformer which provides the galvanic isolation between the DC and AC ports. The modulation strategy consists in duty ratio and phase-shift control under a high and fixed switching frequency, which allows high power density. Unlike existing structures, duty ratio control is performed on the AC side. This approach allows the converter to be designed as an equivalent series-resonant DC/DC converter. With the proposed modulation, reactive and real power open loop control is feasible. Efficiency and performance are compared with the existing Dual Active Bridge (DAB) structure, whose main energy transfer element is the leakage inductance of the HF transformer. For this purpose, analysis of the current flowing through the LC tank is developed. Finally, simulation results are presented to confirm the mathematical predictions.