Research On Isolated Bidirectional Full-bridge DC-DC Converter

With the non-renewable energy consumption, traditional energy such as petroleum and other will cause environmental harm. So the development and utilization of renewable energy are becoming more and more popular in recent year. The DC micro-grid system made up of renewable and energy storage elements are also been widely used. Among these, electric vehicle (EV) has become an important part of energy development strategy in our country because of its advantages of efficient energy utilization. The interaction between EV and distribution network not only brings challenge of large scale access network, but also play a positive role in grid load shifting as distributed energy storage elements. Therefore, the study of isolated bidirectional full-bridge DC-DC converter (IBDC) which as a power electronic interface device between distribution network and EV has a great significance that achieve good interaction between distribution network and EV.According to the characteristics of IBDC converter, this paper researches these three strategies, single-phase-shift control (SPS), dual-phase-shift control (DPS), triple-phase-shift control (TPS) and proposes unified mathematical model. By analyzing control theory of three control strategy, this paper introduces the operating mode of IBDC converter under every control strategy. Then base on the above analysis, the related formula and corresponding mathematical model of the converter are established. Power characteristic analysis of IBDC converter with the three control strategies also has been introduced. This paper points out the transmission power adjustment range and make sure that the TPS control strategy has the best flexibility.Considering the inherent power backflow phenomenon always exists when IBDC converter under the SPS control strategy which will increase the loss of switching device, magnetic elements leader to reduce the system efficient, the paper drives the formula of backflow power when the IBDC converter under these three control strategy. Then point out the relationship between voltage transmission ratio and phase shift ratio. Making sure the DPS and TPS can eliminates the backflow power effectively. Compares the TPS and DPS also, and the former is better than the latter by reducing peak current, RMS current and reactive power. This paper builds a simulation model to verify three control strategies by Matlab/Simulink platform.At last, this paper also builds an experimental prototype and gives the experimental device parameters. Then according to the parameters to select switch devices and design high frequency transformer. The detail of primary side full-bridge circuit, vice side full-bridge circuit and drive circuit are introduced, and dead band phase shift programmed on TMS320F28335 platform. The preliminary tests of three control strategy are completed and get the efficiency of each, verify the accuracy of the theoretical analysis.