Using repetitive control for THD reduction over wide load range for boost digital PFC converters

This paper proposes a control scheme for the reduction of the line current total harmonic distortion (THD) over wide load variation range. A new current sensing scheme is used to detect the average current under fixed or variable switching frequency condition. A repetitive controller is designed to minimize periodic errors within the current loop bandwidth. A design procedure is given for synthesizing the current loop controller to achieve good current tracking under wide input voltage variation range. A single-phase boost PFC converter with single-chip DSP controller has been constructed for the verification of the proposed control scheme. Simulation and experimental results confirm the feasibility and performances of the proposed control scheme.