A Single-Stage Three Phase Bidirectional AC-DC DAB Converter with Multiphase Boost Interfaces

This work proposes a single-stage three-phase bidirectional ac-dc dual active bridge (DAB) converter for interfacing battery energy storage systems with the ac grid. The converter has multiphase boost interfaces at both the ac side and dc sides. The interleaved operation of the multiphase boost units cancels the switching frequency ripples from appearing in the input and output currents and eliminates the filtering requirement at the input and output sides. The ac side of the converter is based on interleaved half-bridge converters. By operating the interleaved converters under sinusoidal pulse width modulation, the converter draws sinusoidal currents at unity power factor from the ac grid. The interleaved operation of the half-bridge converters produces a high-frequency voltage across the switch nodes. It is used for interfacing with the high-frequency transformer for dual active bridge power flow. The dc side of the converter consists of three parallel connected boost converters formed by three boost inductors, three switching legs, and a common dc bus. Two series of connected capacitors form the dc bus on the dc side. The high-frequency transformer terminals at the dc side are connected to the switch nodes of the switching legs and the midpoint of the dc bus in star fashion. The proposed topology is analyzed using the PLECS simulation platform. The simulation results are provided to validate the theoretical claims.