A simple control method of phase-shift full bridge converter to reduce the power loss under light load and standby conditions

In order to reduce the power loss of phase-shift full-bridge(PSFB) converter under light load and standby conditions, this paper proposes a simple control method to achieve zero-voltage switching (ZVS) at light load without any additional auxiliary components. The converter with the proposed control method operates in discontinuous conduction mode (DCM) by decreasing switching frequency and all the energy stored in the magnetizing inductance of the transformer can be made used to provide ZVS by enlarging the dead-time. The ZVS operation can be achieved under light load condition. To reduce the standby power loss, the converter is controlled by burst mode under standby condition. Experimental results show that the lagging-leg switches can achieve ZVS at light load. The efficiency can be improved and the standby power loss is less than 1W. These results confirm the validity of the proposed control method.