Research On Buck-isolated Boost DC/DC Converter

At present,aeronautical static converters mostly adopt two-stage structure of front-stage DC/DC and back-stage DC/AC.The former DC/DC converter is mainly used to realize electrical isolation and provide DC voltage for the latter inverters.DC/AC converters are mainly used to convert DC to AC.In order to meet the requirements of wide input voltage range,high efficiency and high power density,a 500 W 28V/90 V DC/DC converter is developed in this paper.Firstly,the research context of the project is introduced.According to the actual needs,isolated Boost converter is selected.In order to increase the operating range of the input voltage and ensure the efficient operation of the converter in the full input voltage range,a Buck-isolated Boost topology is proposed in this paper.This paper introduces the origin and characteristics of the Non-inverting BuckBoost converter,and compares the advantages and disadvantages of each other according to the differences of control modes,which provides ideas for the control mode of Buck-isolated Boost converter.This paper introduces the basic working principle of this topology in Buck mode and Boost mode.In view of the problem that the leakage inductance of transformer causes the bus voltage spike to be too large,RCD absorption circuit is adopted and its working principle is analyzed.In order to reduce the leakage inductance and the volume of the transformer,the planar transformer is selected as the high frequency transformer.The relationship between the winding mode of the primary and secondary windings of the transformer and the leakage inductance and AC resistance is studied and analyzed.The planar transformer is simulated and verified based on Maxwell software.According to the two modes of the converter,a reasonable control method is selected,and in order to reduce the inductance current ripple,the dual-edge control strategy and the optimization of the transformer turn ratio are adopted,and the small signal model of the converter is modeled in two modes respectively,and the closed-loop parameter design is carried out.Finally,a 500 W principled sample machine is developed and verified by experiments.