An Isolated, bridgeless, quasi-resonant ZVS-switching, buck-boost single-stage AC-DC converter with power factor correction (PFC)

The number of power supplies connected to the public household power grid is constantly increasing. For a good mains voltage quality, the harmonic input currents are limited in standards. Many applications also require a lower output voltage with isolation. Today, this is mostly obtained via a multi-stage converter, consisting of a diode bridge rectifier, a boost PFC and a DC-DC converter with galvanic isolation. For higher efficiency, a bridgeless PFC-stage can be used, but it nevertheless requires a DC-DC converter for isolation. In order to further increase efficiency and decrease component count, a single-stage concept can be used. The Cuk “True Bridgeless PFC” rectifier system, for example, can perform all the requirements in a single stage. A simple application and realization of a converter topology is also quite important, especially in consumer electronics, where costs are crucial. In this paper, a new single stage topology with a different operation principle is presented, focusing on ease of use in hardware realization.