A Phase Shift Full Bridge Converter with Series-Connected Two Transformers Employing a Boost Capacitor

A Phase Shift Full Bridge Converter with Series-Connected Two Transformers Employing a Boost Capacitor

  It is proposed that a capacitor be inserted in the main power flow of the primary side of a phase shift full bridge converter with series-connected two transformers (PSFBC with SCTT) for high efficiency in this paper. This method overcomes the disadvantage of conventional PSFB converter share with PSFBC with SCTT, conduction loss by a circulating current during the freewheeling mode. The primary voltage across the transformers increases due to the voltage across the inserted capacitor, allowing the turn ratio of the transformers to be increased. Furthermore, because of the capacitor, the primary current can be diminished nearly to zero during the freewheeling period so that the circulation energy during that period is reduced. As a result, the efficiency of the proposed converter is higher than that of the PSFBC with SCTT. A mode analysis and experimental results are presented to validate the proposed converter.