A novel method of phase-shifted full-bridge converter to improve efficiency under light load condition

The main theme of this paper is to propose a novel peak current mode control method to reduce the loss of phase-shifted full-bridge (PSFB) converter under light load condition. The proposed control method can adjust the switching frequency of the converter to keep the on-time of switches fixed. According to the loss analysis model in discontinuous current mode operation, the switching frequency is proportional to load current and the efficiency is independent from the load. Moreover, the small signal model of the PSFB converter with the proposed control method is presented. A digital-controlled experimental system is set up. The proposed method is investigated and confirmed by experimental results. Experimental results show that the efficiency and dynamic performance can be improved. These results confirm the effectiveness of the proposed control method.