Novel Bidirectional Single-Stage Isolated Three-Phase Buck-Boost PFC Rectifier System

Future three-phase ac-dc converter systems ideally allow for bidirectional power flow, provide high-frequency isolation, and feature buck-boost capability. Further, high efficiency and high compactness and the applicability of standard half-bridge and/or three-phase full-bridge (B6) semiconductor arrangements are crucial aspects. This Paper proposes a novel converter concept that employs B6-type circuits on the input and on the output side and a low-complexity Discontinuous Conduction Mode (DCM)-type or a Dual Active Bridge (DAB)-type modulation strategy, thereby enabling single-stage isolated three-phase ac-dc power conversion with sinusoidal grid currents and controlled dc output voltage. The converter operation is detailed on the switching-frequency and on the grid-frequency time scale and verified by means of circuit simulations. The converter control characteristic and the main power component stresses are discussed and design guidelines for a 6.6 kW prototype system with an expected efficiency eta > 98% are presented. Finally, an outlook on future research related to the practical realization and advanced modulation of the topology is provided.