Bridgeless Buck-Boost AC/DC Converter with Voltage Doubler Output and BCM Operation

摘要

A Bridgeless double buck-boost AC/DC converter with low conduction losses and no reverse recovery loss on rectifier diodes is proposed to achieve high power factor, low current harmonics and a sinusoidal line current from utility side. The boundary conduction mode (BCM) operation is adopted to control active switches such that the diode reverse recovery problem is overcome and the diodes are turned off at zero current switching (ZCS). The AC source current can automatically follow the utility voltage with nearly unity power factor and active switch is turned on at ZCS. Compared to a conventional boost type AC/DC converter, there is only one diode conduction loss in the proposed circuit. Thus the proposed converter has high circuit efficiency. The voltage doubler topology can double its output voltage to extend the useable energy of capacitor when the line voltage is off. The circuit configuration, principle operation, system analysis, and design consideration of the proposed converter are presented. Finally, experiments for a 250 W prototype are presented to show the performance of the proposed converter.