Research On One-stage PFC AC/DC Converters

Power factor correction techniques have become one of the most important research topics. In order to compliance with IEC 1000-3-2 harmonic regulation and realize low-cost, high-performance, the single-stage power factor techniques have been given much attention these years. Especially in lower power application, single stage power factor correction converters become more and more urgent. In this dissertation the single-stage power factor correction converters are thoroughly studied.A single-stage PFC converter combines the PFC stage and a DC/DC converter into one stage with a shared switch and controller. They can implements the input current shape and provide tight output regulation. Because the flyboost PFC converter has the characters of boost type and the ones of flyback type PFC convert, we present a topological study of representative boost and flyback single-stage PFC converter and analyze the operation principle and characteristics of these single-stage PFC converters thoroughly. The single-stage PFC converters of Boost type can be classified as 2-terminal input current shaper (ICS) cell and 3-terminal ICS cell. Several new PFC topologies were derived from some existed ones using the translation rule of the 2-terminal and 3-terminal ICS cell.In this dissertation, we studied the concept of direct-power-transfer (DPT). The topology with flyboost cell which use the concept DPT is analyzed, the operation principle and characteristics of the topology is depicted in detail.From the experimental results we can see the flyboost PFC cell can achieve a high power factor and low voltage of the intermediate energy-storage capacitors. Moreover, The DPT cell give the system a higher efficiency.