A Family of Single-Stage Resonant AC/DC Converters With PFC

A family of novel, single-stage, isolated, resonant-based AC/DC power supply circuits with inherently high power factor is presented in this paper. The three topologies in the family are transformer isolated; they contain a bulk energy storage capacitor to enable output voltage holdup, and they also contain a resonant circuit in which a resonant capacitor is connected directly across the mains input rectifier. The presence of this resonant circuit results in AC line current being drawn over much of the line cycle, as well as in soft switching of the power devices. The rectifier-compensated fundamental-mode approximation (RCFMA) method is used to provide an accurate yet simple analysis of the circuit. Experimental results for closed-loop operation of two of the topologies are also presented. This family of single-stage, high-power-factor converters provides for simple control and high-frequency operation, due to the resonant configuration of the power circuit, without the excessive conduction loss of fully resonant techniques.