The Design Of Digital PSFB DC-DC Converter

With the rapid development of the world economy, the energy crisis of the world is growing, and requirement for efficiency of energy conversion and utilization has became higher. As an important energy conversion device in power system, switching power supply has a great impact on the efficient use of electric energy. Therefore,research on improving the switching power supply conversion efficiency has became an important issue. Making use of parasitic parameters of the circuit itself to achieve Zero-Voltage Switching(ZVS), Phase-Shifted Full-Bridge(PSFB) DC-DC converter has advantages of simple structure of circuit, low loss and high efficiency, low electromagnetic interference and high reliability. As a result, it becomes the preferred topology for medium-high power switching power supply of high-frequency and has broad application prospects.This paper mainly studied the realization of digital control, high frequency soft-switching technology and Synchronous Rectification(SR) technology in the PSFB DC-DC converter. First of all, the development of PSFB DC-DC converter is investigated in the article. The working principle of PSFB DC-DC converter and the technical difficulties exist in achieving its ZVS are analyzed in detail. Secondly,based on the converter qualification to achieve soft-switching, the main components of PSFB DC-DC converter are calculated and selected. What’s more, according to the designed parameter of components, the simulation platform for PSFB DC-DC converter is built based on Saber and simulation results are analyzed, which verifies the feasibility of the converter. Finally, in order to validate the theoretical analysis, a PSFB ZVS DC-DC converter hardware prototype is set up with its input of 400 VDC,output of 12 V, power rating of 1400 W, switching frequency of 140 kHz. Experimental results are presented and analyzed in detail.Digital control is the development trend of switching power supply, and digital control of PSFB DC-DC converter is implemented, which helps to improve the system anti-jamming capability and cost savings. The soft-switching realization ofmain power switches significantly reduces switching losses and switching noise of power devices. Synchronous Rectifier are adopted in converter transformer secondary side, which reduces conduction losses of the rectifier circuit and increases the conversion efficiency.