High Efficiency Three-Phase Unidirectional Buck-type PFC Rectifier Concepts

This paper presents highly efficient three-phase unidirectional buck-type unity power factor rectifiers well-suited for various power electronic applications such as high power EV battery charging or DC distribution systems. The circuits are assembled by incorporating two auxiliary circuit branches into standard three-phase buck-type PFC topologies, each one comprising of one active switch and three diodes. This enables redundant current paths for distributing the impressed output DC currents to the AC input terminals, which can be potentially used to reduce the system's total semiconductor losses and/or increase its output power capability. The advantages of a new converter constructed with a three-phase six-switch buck-type PFC, including the principles of operation, modulation strategy and suitable control structure are described in this paper. Finally, the proposed converter is compared with the conventional six-switch buck-type converter and SWISS rectifier. According to the results, the studied AC-to-DC system is the topology of choice for a buck-type PFC.