A resonant single-stage PFC AC-DC converter

Line connected electronic devices have to meet ever stringent limitations regarding EMC. One of those standards, the IEC 61000-3-2, limits the line current´s low frequency harmonic spectrum. In case of switch-mode power supplies, meeting the IEC 61000-3-2 typically increases circuit complexity and with it costs. Thus, there is a strong wish to realize the required input current shaping with the lowest effort possible. The common approach is an active power factor correction scheme where a second converter is placed between input rectifier and bus capacitor. In contrast, single-stage topologies implement input current shaping and isolated output power processing with one switching stage (preferably a single switch). The benefits are said to be lower costs, higher efficiency and smaller overall converter volume. The majority of proposed single-stage converter employ common hard-switching DC-DC topologies as basis. In contrast, this paper picks up promising earlier work done on single-stage topologies employing resonant power conversion. The proposed converter is thoroughly analyzed and optimization results for an exemplary 20-V, 100-W universal line voltage power adapter are provided.