Single-stage single-switch power-factor-correction AC/DC converters with DC-bus voltage feedback for universal line applications

Single-stage single-switch power-factor-correction (S/sup 4/-PFC) AC/DC converters with DC-bus voltage feedback are proposed. The DC-bus voltage stress at light load for the S/sup 4/-PFC converter is first analyzed. The DC-bus voltage negative feedback concept in the power stage to suppress the DC-bus voltage stress is then proposed. Design considerations of total harmonic distortion (THD), power factor (PF), DC-bus voltage stress, and the boost inductor are discussed. A S/sup 4/-PFC converter is analyzed and implemented with 5 V 12 A output as an example. It is shown that the DC-bus voltage is limited within 405 V from no load to full load, and the measured line input-current harmonics satisfy the IEC 1000-3-2 Class D requirements with universal line input. The measured efficiency and PF are about 71% and 0.93, respectively. The experimental results show that using the DC-bus voltage feedback to reduce the DC-bus voltage is effective.