Resonant Bridgeless Buck PFC Converter With Reduced Components and Dead Angle Elimination

The inherent dead angles of the input line current in buck power factor correction (PFC) converter deteriorates the power factor (PF). This article introduces a new bridgeless single-phase buck (PFC) converter with reduced components. This converter is designed to operate in discontinuous conduction mode (DCM) to achieve inherent PFC with a simple structure. The DCM operation gives additional advantages, such as low turn-
on
losses and reduced complexity of the control circuitry. Unlike the buck PFCs, in which dead angle is the main drawback, in the proposed converter the PF is improved and the dead angle is eliminated by applying an auxiliary switch. Besides, the efficiency is further improved by employing the bridgeless structure. The switching losses are eliminated due to achieved zero current switching (ZCS) at the turn-
on
and turn-
off
of the main switches, and also ZCS at the turn-
on
and zero voltage switching at turn-
off
of the auxiliary switch. The proposed topology is successfully implemented on a 120 W prototype converter at 110 Vrms input voltage and 48 V output voltages, and its performance is experimentally verified. The results show the total harmonic distortion of 5.3% and efficiency of 93.1% at the rated load.