New "Real" Bridgeless High Efficiency AC-DC Converter

In this paper, a new bridgeless single-phase ac-dc converter with a natural power factor correction (PFC) is proposed. Compared with existing single-phase bridgeless topologies, the proposed topology has the merits of less component counts. Other advantages include: simple structure, soft switching, common ground, electrical isolation, and simple control circuitry. The absence of an input diode bridge and the presence of only one diode in the current path during each stage of the switching cycle result in higher power density and less conduction losses; hence, improved thermal management compared to existing PFC rectifiers is obtained. The proposed topology is designed to work in resonant mode to achieve an automatic PFC close to unity in a simple and effective manner. Principle of operation and the feasibility of the proposed converter are provided. The measured efficiency of the proposed converter at low line (85-V-rms) line voltage is near 95%. Detailed experimental and simulation results are presented.