Switching Control Method for Light Load Efficiency Improvement in Phase Shifted Full Bridge Converter

In this paper, a new switching control method for light load efficiency improvement in phase shifted full bridge (PSFB) converter is proposed. The main advantage of the proposed method is that it does not use any additional component in power conversion stage, so that it does not have any additional loss. By using simple "AND-gated" control signals for synchronous rectifier (SR) and optimized dead time for primary switches, it is possible to get not only reduced core losses, but also ZVS operation even in light load condition. Therefore, the proposed switching control method reduces switching and core losses in light load condition so that it shows remarkably increased light load efficiency. The feasibility of the proposed switching control method has been verified by experimental results with 90-264V(ac) input, 400V link voltage, 12V output voltage, and 750W output server computer power supply system.