Research On Phase-Shifted Full-Bridge ZVS Dc-DC Converter

Phase-shifted full-bridge ZVS DC-DC converter is favored in medium and high power applications due to its characteristics of constant frequency operation,simple topology,high power density and utilizing the resonance between its own circuit to realize ZVS.However,conventional phase-shifted full-bridge ZVS converters still have drawbacks such as limited soft switching range,loss of circulating current-related power,loss of secondary side duty cycle,and parasitic oscillation on rectifier diodes.This leads to the limitation of optimization performance of the full-bridge converter application,and becomes a hot issue that most scholars are trying to explore.The key problems of the phase-shifted full-bridge converter are discussed in this paper.On the basis of a summary of the corresponding solutions,the measures to improve the performance of the converter are mainly studied,and then two new improvements are proposed.The main research work of this paper is as follows:Firstly,the working principle of the traditional phase-shifted full-bridge ZVS converter is analyzed,and the key problems in the work are discussed.Then the parameter design and simulation analysis are carried out.The simulation reflects the accuracy of the analysis.In addition,the related solutions proposed for the above work defects are summarized,and some typical topologies and modulation strategies are classified and the advantages and disadvantages of each scheme are compared with the characteristics.Secondly,an improved full-bridge ZVS converter based on complementary duty ratio is proposed.The converter widens the soft switching range and greatly reduces the duty cycle loss through the auxiliary resonance network,and eliminates the parasitic oscillation problem of the rectifier bridge through the primary clamping network.In this paper,the working principle and characteristics of the converter in detail are analyzed,and its main circuit parameters design is discussed,its related characteristics are verified through simulation.Then,an improved full-bridge converter based on secondary phase-shift modulation is proposed.The converter eliminates the primary phase-shifting phase through the characteristics of the secondary phase shift,and then eliminates the problem of circulating current loss.Due to the introduction of the CDD energy recovery reset circuit,there is no problem of loss of duty cycle loss,and the rectifier bridge parasitic oscillation is suppressed,the secondary switches can achieve a wide range of ZCS,and the primary switches can achieve ZVS under heavy load conditions.In this paper,the working principle and characteristics of the converter are analyzed in detail,its main circuit parameters design is discussed,and its related characteristics are verified through simulation.Finally,the research contents of the paper are summarized,and the problems that need further research and solution are pointed out.