Research On Dual-active Full-bridge DC-DC Converter Based On Triple Phaseshift

This topic takes the dual-active full-bridge bi-directional DC-DC converter current problems that cause high current stress and low efficiency as project background,study the factors affecting the efficiency,use three phase shift control strategy to replace the traditional single phase shift control strategy,and apply the fundamental wave analysis method to the establishment of the model of system,put forward the optimization of three phase shift control strategy.The main research content of this paper is as follows:The single-phase control strategy is applied to series LC resonant type DC-DC converter.First,the working area is selected and the appropriate switching frequency is selected.Then working waveforms under the single phase shift control strategy are analyzed,and each working mode is introduced respectively.Aiming at the low efficiency of traditional single-phase shift control strategy,the loss of each part of series LC resonant type DC-DC converter is analyzed,which shows the influence of resonant current on the efficiency and provides theoretical basis for the subsequent analysis and strategy optimization.The three-phase shift control strategy is applied to LC resonant type DC-DC converter,and its principle is analyzed.For three phase shift control strategy we do a brief introduction,and in practical application,based on the output voltage and the input voltage square wave rising edge and falling edge classify its working condition,after the classification carry on a detailed analysis and introduction of its work mode circuit and a detailed analysis for each work mode,provides theoretical basis for three phase shift control strategy optimization.In order to solve the problems of high current pressure and low efficiency,the threephase shift control strategy was optimized.The fundamental wave analysis method was used to model and analyze the system,on the basis of the conditions for obtaining the minimum resonant current square root value obtain the optimized three-phase shift control strategy.In order to compare convenience,we have the same modeling and analysis of single phase shift control strategy,for both from the aspects such as transmission power and the current size,shows the superiority of the optimization of three phase shift control strategy,in the case of light load application use optimization of three phase shift control strategy can significantly lower current square root value of resonance.In order to prove the feasibility and superiority of the optimal three-phase shift control strategy,a Simulink simulation model of the dual-active full-bridge resonant type bidirectional DC-DC converter was established.Analyze its software design,and optimization of three phase shift control strategy and the traditional single phase shift control strategy was used in the topology at the same time,the simulation results are compared from resonant current,fundamental wave,output current,and other aspects in order to verify the superiority of the optimization of three phase shift control strategy,shows that optimization of three phase shift control strategy can lower the current pressure and improve efficiency.