Research And Design Of High-Power Isolated Bidirectional DC-DC Converter

With the rapidly developing of new energy technologies,its clean and efficient feature catch more and more attention.National also vigorously promote the development of new energy technologies on electric vehicle,UPS and micro-grid.As the function of storage and conversion energy,the composite energy storage system become an important part of new energy technologies.The bidirectional DC-DC converter which used to transmitting energy between energy storage devices and power grid play a key role in the composite energy storage system.Its performance indexes direct influence the whole composite energy storage system,its research is very important.This article firstly collected and researched all kind of bidirectional DC-DC converter in the existing data,detailed analysis these features on topology and performance.With considering the feature of composite energy storage system which based on super-capacitor and storage battery,this article choice the topology of full-bridge isolated bidirectional DC-DC bonverter as the power stage and analysis the function of each part.For the selected topology,its operating principle and model has been deeply studied in this article.Then designed bipolar control method and shift control method to achieve the step-up and step-down operation which aims to achieve the energy flow between different energy storage units.A Simulink simulation model of bidirectional DC-DC converter is built,and verified the design of topology and operating principle.On that basis,this paper constructed the steady state equivalent model and AC small-signal model of bidirectional DC-DC converter.As these model,this paper completed to analysis of time-domain and frequency-domain feature and design control circuit.Finally,the whole converter of power circuit,control circuit and software are designed in detail.This design includes the parameter design of isolation transformer,inductor and the reasonable selection of IGBT module,control chips,detection chips and other components.After the hardware design of the system,phototype and experimental platform of bidirectional DC-DC converter has been built.The conversion experiments between 28V and 270V was verified on it.Experimental results show that the design of bidirectional isolated DC-DC converter can meet all the requirements of different used environment.Some suggestion which based on RC circuit and current sharing technology of optimization has been discussed,these suggestions can improve the performance of bidirectional DC-DC converter in this paper.