A variable DC link approach for high power factor three-level single-stage PFC converter

To reduce the cost of the conventional two-stage power factor correction (PFC) converters, single-stage PFC (SSPFC) converters have been studied in literature. Most commonly, the SSPFC converters are operated at DCM mode due to the simplicity of the control, non-existence of the reverse recovery losses. For ac/dc converters supporting universal input voltage range, DCM operation with relatively low dc link voltage results in highly distorted input current. In multi-level SSPFC converters, the dc link voltage can be adjusted in a larger window between 400V-800V thanks to the reduced voltage stresses on the switches. Thus, with an integrated controller adjusting dc link voltage with respect to line voltage, power factor at high line voltage can be improved. However, in DCM mode, the efficiency of the converter slightly decreases at high dc link voltage. In this paper, the tradeoff between the efficiency and the input factor is analyzed in a new integrated three-level PFC converter.