Current Stress Optimization And Peak Current Control Method For Dual Active Bridge Converter With Extended Phase-shift Modulation

Dual Active Bridge(DAB)converters have the advantages of high power density,bidirectional power transfer capability and electrical isolation,which will be served as the core circuit for electric vehicles and energy storage systems.How to improve the efficiency of DAB converters and how to suppress dc bias have regained the attention of numerous researchers.Aiming at the above problems,this paper analyzes the working principle of DAB converter,researches an extended phase-shift(EPS)modulation method to improve efficiency,and designs a peak current controller for EPS to avoid the risk of transformer saturation by suppress DC bias of transformer current.Firstly,the working principle and switching state of DAB converter with single phaseshift(SPS)modulation and EPS modulation are introduced.The formulus of transmission power,current stress and zero voltage switching(ZVS)region under the two modulation methods are deduced respectively,and the working characteristics of the two modulation methods are compared.The conclusion that EPS modulation is more advantageous is drawn.Secondly,to improve the efficiency of the converter,the minimum current stress condition of DAB was deduced,and an optimized EPS modulation method is proposed considering the current stress and ZVS range.The current stress of DAB with this method is close to the minimum,and ZVS condition is satisfy.Thirdly,aiming at the problem of transformer saturation in DAB converter,the working principle of peak current control is analyzed,and the peak current control method for dual active bridge converter under EPS modulation is designed to avoid the risk of transformer saturation by suppress DC bias of transformer current.Finally,the simulation model and DAB hardware experimental platform are built to analyze and verify the optimized EPS modulation method and peak current control method proposed in this paper.The simulation and experimental results prove the rationality of the research content.