An Optimized Single-Stage Isolated Swiss-type AC/DC converter Based on Single Full-Bridge with Midpoint-Clamper

The Swiss-type rectifier (SR) uses harmonic injection circuit and two DC-DC converters to help three-phase uncontrolled rectifier bridge to achieve better power factor correction (PFC). By applying the full-bridge topology to the DC structure, both the soft switching and the high frequency galvanic isolation can be achieved. However, two full-bridge structures are required to realize the PFC principle of Swiss-type rectifier. That means the current flows through at least four switches and two transformers during the power conduction or freewheeling period. There are improvements in both conduction loss and core utilization. Thus, an optimized single-stage isolated Swiss-type AC/DC converter based on single full-bridge with midpoint-clamper is proposed. Only one full-bridge structure is used to improve the conduction loss and core utilization. Two bidirectional voltage clamper are used to implement the PFC principle of the SR. The performance of the proposed converter has been verified by experiments. 95.4% efficiency under half rated power and 5% input current THD under rated power have been achieved under a 10 kW 380 Vac input/400 Vdc output prototype with 90 kHz switching frequency.