Research On On-Board DC/DC Charge Power Supply With Phase-Shift Full Bridge

In recent years,in order to save fossil fuels and effectively control greenhouse gas emissions,the research on the technology development of new energy vehicles has become more and more intense.DC/DC converter is an indispensable key part of electric vehicle,and its research and development has also attracted the attention of the industry.On-board DC/DC power supply has the advantages of small size,high efficiency and reliability,which makes it have huge market potential.Therefore,the development of on-board DC/DC power supply has become one of the most popular projects of power companies.The DC/DC power supply studied in this paper is a single-stage ZVS phase-shifted full-bridge DC/DC converter with input voltage range is 250-430 V,output voltage range is 9-16 V and maximum output power is 2.5kW.The control chip is UCC28950.The secondary side uses synchronous rectification to further improve efficiency.The general circuit consists of the main circuit,control circuit,detection circuit and EMI circuit of the phase-shift full bridge.Firstly,the development status of DC/DC converters and the reasons for choosing phase-shifted full-bridge topology are described.Zero Voltage Switching(ZVS)soft-switching technology is selected to reduce switching losses and improve converter efficiency.Then,the working principle and characteristics of ZVS phase-shift full bridge main circuit are analyzed in detail,the reasons for the loss of secondary duty cycle and parasitic oscillation of output rectifier are explained,and the main circuit topology is improved.According to the working characteristics and technical specifications of phase-shift full bridge converter,the main components of the main circuit of phase-shift full bridge converter are designed and selected firstly,including high frequency transformer,resonant inductor,output filter inductor and main powertransistor,etc.Then the simulation model of the main circuit is built by Saber software,and the main circuit parameters are simulated,the correctness of the design is verified.The small signal model of the main circuit is established,and the transfer function of the main circuit is obtained according to the model.The peak current control strategy is adopted,and a double closed-loop controller is designed.The simulation with Matlab software proves that the designed loop has good stability and dynamic performance.Then the peripheral circuit and driving circuit of UCC28950 are designed.Finally,the relevant waveforms and efficiency curves are obtained through the experimental test of the prototype,which verifies the correctness of the design.