Research On PSFB Topology Based Switching Power Converter For Vehicle

With the popularization of electric vehicles,the switching power converter for vehicle has gradually become a research hotspot of enterprises and research institutes.It's related to performance and drive safety of electric vehicles that whether we can design high-power,high-efficiency,stable and reliable switching power converter.The work of this paper came from the 500 W switch power converter designed by the author and a vehicle electronics company.Firstly,this paper summarizes the development status of switching power converter for vehicle in recent years,and analyzes the design schemes of other scholars.It analyzes the topology selection,hardware design,control strategy and mechanical structure of these schemes,and explains the advantages and disadvantages of them.Secondly,the advantages and disadvantages of several existing topologies were studied.The phase-shift full-bridge and synchronous rectification topology were selected as the power circuit topology of switching power coverter for converter.The operation mode of phase-shift full-bridge circuit was analyzed.Several problems that may arise were listed,and some feasible solutions to these problems were proposed.Thirdly,the design requirements of switching power converter for vehicle were clarified.The main parameters of the main transformer,bus capacitor and output filter inductor were determined and the models of the power MOSFET were selected.After determined the component parameters of the main circuit,the driving circuit of the MOSFET,the isolation circuit between the high and low voltage,the main relay circuit,and the sampling circuit were designed.Fourthly,a fuzzy control strategy with feedforward loop based on PSFB topology was proposed,which is digitized by DSP.At the same time,subroutine for controlling the operation of the switching power converter,such as soft-start subroutine and state machine subroutine,and a new PWM control strategy was designed to realize the magnetic balance of the transformer.Finally,an experimental prototype was made.The PWM control signals of the prototype and key signal in other control circuits were sampled during operation of the switching power converter.In addition,the load was quickly changed between 100 W and 500 W,and the output voltage and current waveforms were sampled for analysis.The effect of the control strategy was verified.