Single-stage AC-DC power-factor-corrected voltage regulator with reduced intermediate bus voltage stress

Single-stage power-factor-correction (PFC) circuits usually suffer from high rising intermediate bus voltage stress at light load condition due to power imbalance between the input and output. Also the conversion efficiency is low due to repeated power processing. A single-stage AC-DC power-factor-corrected voltage regulator (PFCVR) is presented for which a portion of the input power is transferred to the output directly after the first power process, resulting in lower voltage stress on the intermediate bus storage capacitor while achieving a high power factor. Conversion efficiency is also improved. In addition, the duty ratio is a function of the load so that the bus voltage decreases when the load is decreased. PFC and fast output regulation are achieved through a proposed simple single-loop voltage feedback controller. Parameters affecting the voltage stress on the intermediate bus capacitor and the input power factor are examined. Experimental results to verify the operation and performance of the converter are also reported.