Investigation of Key Technique for High Efficiency and High Power Density, Single-Stage Power Factor Correction AC/DC Converter

Dedicated to such industry requirements as high power, rigorous harmonic standard and isolation, a novel solution that combines the topology of full-bridge and fully digital controller is presented. This paper deals with a 5 KW power factor correction (PFC) converter that is based on the topology of single-stage (SS) full-bridge (FB) structure with input current shaper and RCD clamping circuit. Especially, the clamping capacitor can partly return its stored energy. A transformer used to provide galvanic isolation allows a wide range of output, offering multi-output solutions. The adopted improved digital strategy features fast dynamic response and excellent steady regulation, in addition, problem of flux density bias for the transformer that occurs in analog control strategy is successfully solved without any auxiliary circuit. Both power stage and density are drastically improved. High power factor and high efficiency are achieved. The excellent performances of the converter are verified by a prototype, whose rating output power is 5 kW and PFC operating frequency is 55 kHz. Furthermore, PF value and efficiency of full load are respective 0.994 and more than 92%.