Bridgeless High-Power-Factor Buck-Converter Operating in Discontinuous Capacitor Voltage Mode

In this paper, a new bridgeless single-phase ac-dc power factor correction (PFC) rectifier based on buck topology operating in discontinuous capacitor voltage mode (DCVM) is proposed. The bridgeless topology and the presence of only one or two semiconductor switches in the current flowing path during each interval of the switching cycle result in lower conduction losses compared with the conventional DCVM buck PFC rectifier. The DCVM operation offers additional advantages such as zero-voltage turn-off in the power switches, zero-voltage turn-on in the output diode, and continuous input current. Hence, the electromagnetic interference noise emission is minimized. The converter achieves high power factor naturally with low total harmonic distortion in the input current. Theoretical analysis and experimental results for 100 W/48 V_dc at 100 V_rms line voltage are provided to evaluate the performance of the proposed scheme. The measured conversion efficiency reached 96.3%.