Single-stage single-switch power factor correction (S4-PFC) AC/DC converters with DC bus voltage feedback for universal line applications

Single-stage single-switch power factor correction (S⁴-PFC) AC/DC converters with DC bus voltage feedback are proposed. DC bus voltage stress at light load for the S⁴-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. A S⁴PFC 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 input current harmonics satisfy the IEC 1000-3-2 Class D requirements with universal line input. The measured efficiency and power factor are about 71% and 0.93, respectively. The experimental results show that DC bus voltage feedback to reduce the bus voltage is effective