Research On High Power Density DC/DC Modular Power Supply

With the rapid development of modern industrial and national defense, the technical requirements for DC/DC modular power supply, such as power level, voltage level, efficiency, size and weight, need to be improved. In this paper, a wide and high input voltage full-brick DC/DC power module with28V/1kW output is mainly studied, and then the advantages and disadvantages of several circuit topologies, which are applicable to high power density DC/DC power modules, are analysed and compared. Therefore, a two-stage DC/DC topology of primary series transformer LLC and output interleaved Buck, which is suitable for the technical requirements of the project, is presented in this paper.In Chapter Ⅰ, the background, status quo and development trend of DC/DC modular power supply is introduced, and then, several topologies, which are suitable for DC/DC modular power supply, are analyzed, including the advantages, disadvantages and applicable occasions.In Chapter Ⅱ, the operation stages and efficiency comparison are analyzed between phase-shifted full-bridge converter, Boost and LLC with series/parallel transformers cascaded converter and primary series transformer LLC and output interleaved Buck cascaded converter. The theoretical studies show that two-stage topologies have some advantages in terms of efficiency.In Chapter Ⅲ, the design principle of Boost and LLC with series/parallel transformer cascaded converter is analysed, including parameter design and power devices selection. The voltage regulation is achieved by the first stage Boost, and the electrical isolation and voltage step-down are realized by the second stage LLC. An output of28V/1kW prototype is implemented and the theoretical analysis is validated by experiments.In Chapter Ⅳ, a two-stage DC/DC topology, which consists of primary series transformer LLC and output interleaved Buck, is designed. The operation stages of the converter and the parameter of the LLC is designed in this chapter, and the steady-state output current sharing are analyzed even with mismatched parameters, such as high frequency transformers’turns ratio and the duty cycles of Buck circuit. An output of28V/1kW prototype is implemented and the theoretical analysis is validated by simulation and experiments.Finally, a summary of this paper and some prospects have been made.