Research Of Phase Shift Full Bridge DC/DC Converter Based On DSP

Zero Voltage Switching Full Bridge Converter (ZVS-FB) has been widely used in medium to high power level because of its many advantages. This thesis mainly focuses on two issues: the main circuit configuration of ZVS-FB DC-DC converter with auxiliary networks and the implementation of digital control scheme ZVS-FB converter.Firstly, the difference to achieve ZVS with different parameters has been discussed and the principle of abnormal transition process has been investigated in this paper. The constraint equations are deduced quantificationally to ensure the ZVS realized independence of the load condition. Then, a novel optimal design method is proposed. These conclusions are verified by prototype testing results.Secondly, many kinds of methods to suppress the voltage spike of rectifier diodes in ZVS-FB converter are discussed;the "synchronization problem", which is very important in the system composed of parallel converters or cascade converters, is introduced and several synchronization methods are analyzed respectively through simulation and experimental results.Finally, some pivotal issues of digital control technology are discussed;the small signal circuit model of ZVS-FB converter with double loop control is deduced and the duty-cycle loss has been taken into account. Then, A novel phase shift pwm generation method is proposed and based on this method, the arithmetic handling unbalance of the magnetic core of transformer have been analyzed. Based on these analyses, the digital control hardware implementation and control program of a 500W ZVS-FB prototype are designed and experimental results are given.