Design Of Phase-shift Bidirectional Full-bridge DC-DC Converter

With the development of green energy,bi-directional DC-DC converter becomes more and more widely used.It not only has the function of cutting peak and filling valley in the energy storage system of microgrid,but also can improve the charging and discharging life and life-span of electric vehicle in the power conversion system of electric vehicle.And in the field of aerospace fuel cell management devices to make full use of the drive motor system energy.Therefore,the research and design of bi-directional DC-DC converter has very important application value.In this paper,after comprehensively analyzing the five topological structures of the isolated converter,the converter designed in this paper is determined to be a bidirectional full-bridge structure,and then the topology composition and working principle of the bidirectional full-bridge DC-DC converter are explained.After that,the control mode of the converter is determined to be a phase shift control mode.Then,the SPS and DPS control methods are studied separately.After analyzing the various operating modes of the two controls in detail,the reason that affects the operating efficiency of the converter is the reflow power generated when the voltage and current polarities are inconsistent.In order to eliminate the reflow power,the transmission power of the two controls is mathematically modeled,and the magnitude of the reflow power is determined by the shift.Based on the shift,the Lagrangian function is used to design an optimal control algorithm to reduce the maximum value of the inductor current and decrease the reflow power.Through the discussion of the soft switching range of the bidirectional full-bridge DC-DC converter and the comparative analysis of the PSCAD simulation waveform,it is concluded that the bidirectional full-bridge DC-DC converter optimized under DPS control has smaller reflow power and can keep the converter constant.The output of the voltage value makes the converter work more efficiently.According to the research results,the hardware and software design of the bidirectional full-bridge DC-DC converter is done.Firstly,the overall structure of the hardware is determined.According to the overall structure,the main circuit,the sampling conditioning circuit,the control circuit and the driving circuit are respectively designed.Then,the main program of the bidirectional full-bridge DC-DC converter,the interrupt subroutine and the PWM program are software-designed.Finally,a small test prototype was built according to the design scheme,and the feasibility of the design scheme was verified by the test results.