A novel control technique for an AC/DC converter used in telecom applications

In this paper, a novel control approach is proposed for an AC/DC converter used in Telecom applications. The proposed control system is able to improve the converter performance over a very wide range of operating conditions. The proposed control approach is based on a new Self-Sustained Oscillating Control (SSOC) loop, in order to adaptively change the phase-shift and the switching frequency of the converter for different operating points. In particular, the switching timing signal is produced based on the transformer primary current, which is a feedback to the SSOC loop in order to determine the switching instants of the power MOSFETs. Therefore, the control system automatically tunes the control variables for different operating conditions. The converter performance with the proposed control technique is analysed through computer simulation as well as experimental prototype. Simulation and experimental results demonstrate the superiority of the performance compared to the conventional phase-shift control approach.