Three-phase isolated full-bridge boost PFC with flyback passive auxiliary converter

A three-phase isolated full-bridge boost power factor correction (PFC) converter with a flyback passive auxiliary converter is presented and investigated. The PFC converter operates in discontinuous conduction mode (DCM), it can achieve zero voltage turning off for the upper switches and zero voltage turning on for the lower switches. With the adoption of the passive auxiliary converter, the voltage spike of the PFC converter is suppressed efficiently, and during one charging period, the absorbed energy can be transferred to the load by itself, from which the stresses of main circuit can be reduced. The operational process of the PFC converter is analyzed in details, and design considerations of both the PFC converter and the auxiliary converter are given. Finally, the feasibility of the presented method and the validity of the theoretical analysis are verified by the experimental results.