A novel method for elimination of line-current harmonics insingle-stage PFC switching regulators

摘要

This paper studies a particular single-stagenpower-factor-correction (PFC) switching regulator employing andiscontinuous-conduction-mode (DCM) boost-input cell and ancontinuous-current-mode (CCM) forward output cell. Although thisnsingle-stage PFC regulator can provide a reasonably high power factornwhen its PFC stage is operating in discontinuous mode, substantialnreduction in line-current harmonics is possible by applying a suitablenfrequency-modulation scheme. This paper derives a frequency-modulationnscheme and proposes a practical implementation using a simplentranslinear analog circuit. A quantitative analysis on the totalnharmonic distortion (THD) of the line current when the circuit isnsubject to a limited range of frequency variations is presented alongnwith some considerations for practical design. Experimental datanobtained from a prototype confirms the effectiveness of the proposednfrequency-modulation scheme. The proposed analog translinear circuitnallows custom integrated circuit implementation, making it a viablenlow-cost solution to the elimination of line-current harmonics innswitching regulators