High-power-factor single-stage converter with robust controller for universal off-line applications

This paper presents a robust-controlled single-stage converter (SSC) operating either in discontinuous conduction mode (DCM) or in continuous conduction mode (CCM) to achieve high power factor for universal line voltage range from 90 to 264 V_rms. At light load, the proposed system is operated in the DCM, while at heavy load the system is operated in the CCM, thus, the DC-link voltage can be properly controlled within a certain voltage range and the efficiency can be improved as well. The overall system is with a robust controller and is operated in a fixed frequency. In the design, the load variation and line voltage variation are treated as plant uncertainty and control disturbance, respectively. The H^∞ robust control method is adopted to design a proper robust controller to achieve robust stability and robust performance. The measured results from a prototype have confirmed the effectiveness and feasibility of the proposed system