Double-Line Frequency Ripple Suppression of a Quasi-Single Stage AC–DC Converter

Abstract

Owing to the instantaneous difference between variable AC input power and the constant DC output power, power factor correction (PFC) converter suffers from serious double-line frequency (DLF) output voltage ripple. A Ripple-Suppressor (RS) in series with the PFC converter, which generates same magnitude but 180° phase shifted voltage as PFC converter output voltage ripple, is utilized in this brief to suppress the DLF output voltage ripple. The relationship among output impedance, audio sensitivity and output voltage ripple coefficient is analyzed, the closed-loop audio sensitivity and the stability of DLF ripple suppressor with constant on-time (COT) control are investigated. RS using a COT-controlled Buck converter can suppress DLF voltage ripple effectively with fast dynamic response and improved efficiency. Simulation and experimental results are given to verify the theoretical analysis.