Research On High-gain Symmetric Bidirectional LCLC Resonant Converter

In the system of new energy power generation,the bidirectional DC/DC converter connecting the DC bus and the energy storage system plays an important role,and has a high requirement on the voltage input range of the converter.Therefore,the research of high gain bidirectional DC/DC converter research is very important.In order to increase the input voltage range of the bidirectional DC/DC converter,a high gain symmetric bidirectional LCLC resonant converter is proposed in this paper.The proposed resonant converter does not use the magnetizing inductor of transformer to participate in resonance.And a parallel LC branch is added on the primary side of the transformer to participate in resonance,so that the converter still has a large gain with a large inductor ratio.The balance between high efficiency and large gain range at the resonance point is achieved.The proposed resonant converter can also ensure the soft switching both on the primary and secondary side,and can realize the symmetric bidirectional operation.First,a high-gain symmetric bidirectional LCLC converter is proposed,and its working principle is described in detail.The proposed converter is mathematically modeled with First harmonic approximation(FHA),and its gain formula and resonance current formula are derived using the fundamental wave equivalent model.This equivalent model makes a foundation for studying the characteristics of the converter.Secondly,according to the results of mathematical model,the characteristics of the proposed converter are studied in depth,how each resonance parameter affects the gain change of the converter,the influence of the magnetizing inductance of the converter on the gain is studied,and it is compared with the traditional bidirectional LLC resonant converter,and the newly added LC branch of the proposed converter is studied,how it affects the performance of the converter,and the reason for its high gain is revealed.Then according to the characteristics of the proposed converter,according to the design index,the method of the converter resonant parameters is given,the corresponding design flow chart is given,and the design method of the transformer and inductor used in the converter is given,and the control circuit of the converter The current and voltage sampling in is designed,and the software design flow chart is also given.Finally,the simulation software was used to verify the forward and reverse operations.a bidirectional DC/DC converter experimental prototype was built based on the designed experimental prototype results.Both simulation and experimental results verify the correctness of the theoretical analysis of the proposed converter and the practical feasibility and effectiveness of the proposed topology.There are 50 figures,4 tables and 65 references in this paper.