Research On Hybrid-Switching Phase-Shift Full-Bridge On-Board Charger

With the popularity and promotion of electric vehicles,more and more families,businesses purchase electric vehicles as a means of transport.Electric car charger as a necessary supporting equipment,with broad market prospects.How to improve the efficiency of the converter,reduce the equipment size and improve the reliability become the focus of the study of scholars.1)Firstly,this paper introduces the research background of electric vehicle charger as well as the design requirements.The traditional phase-shift full-bridge converter and its improved topology structures are introduced,and this paper analyzed the advantages and the disadvantages of these improved topology.2)The working process of the hybrid-switching phase-shifted full-bridge converter(HSPSFB)is analyzed in detail.For the different stages of the converter's working prosess,this paper gives its mathematical models.After studied the static characteristics of the hybrid-switching phase-shifted full-bridge converter,by theory and the related formula derivation,the hybrid-switching phase-shifted full-bridge converter has been proved having better performance than the traditional phase-shift full-bridge converter,and is verified by simulation.The HSPSFB converter's parameters are optimized design,especially the resonant inductance and resonant capacitance's design principles.At the same time the selection method of the main power devices are given.3)This paper calculated the gain curve of the HSPSFB converter with the numerical calculation method for the first time,which conducive to the further optimization of control system and the parameter design.The parasitic parameters of the converter and its influence are analyzed in detail.This paper studied the oscillations caused by the parasitic parameters,and the different parasitic oscillation phenomena under different working conditions,which enrich the principles of parameter selection.For the problem of large current stress in the process of soft start,this paper studied the traditional slope soft start scheme,and proposes the variable frequency slope soft start scheme,through the simulation proved the effectiveness of the scheme of variable frequency slope soft start scheme.By keeping the same start time,the current stress has been significantly suppressed.4)At last,the experimental platform of HSPSFB converter which is designed with DSP28335 chip as the control core is set up.The theoretical analysis and experimental verification is carried out and the correctness of the theoretical analysis in this paper is proved.