Research On Dual Active Bridge LLC Resonant DC-DC Converter

With the rapid development of bi-directional interaction technology,energy storage technology and micro-grid technology,isolated bi-directional DC-DC converter,which can realize bi-directional power transmission,has increasingly broad application prospects in these technical fields.In this paper,based on the bidirectional interaction between electric vehicle and power grid,the working characteristics and resonance parameters optimization of LLC resonant DC-DC converter with bidirectional full bridge are studied.Firstly,on the basis of discussing the working mode of the two-way full-bridge LLC resonant DC-DC converter,analyzing the specific working process of the circuit under the control of frequency conversion and phase shift,the fundamental wave analysis method is used to model the converter,and the working characteristics of the converter are discussed.The restriction relationship between the ratio k of primary resonant inductance and excitation inductance based on the maximum value of inductive voltage gain and the soft-ness are derived.The switching conditions restrict the quality factor Q.A design method of optimizing the parameters of resonant network by combining mathematical analysis with graphics is proposed,which needs no iteration of parameters and is fast and accurate.Secondly,the main circuit parameters and some key circuits of the two-way full-bridge LLC resonant DC-DC converter are designed.The parameters of the resonant network are designed by using the above-mentioned parameter design method.A new wide-bandgap semiconductor device,SiC MOSFET,is selected as the switching device.Combined with the specific characteristics of the converter,the driving scheme of the corresponding SiC MOSFET is designed.Finally,in order to further verify the correctness of theoretical analysis and parameter optimization,PSIM simulation software is used to verify the simulation.On this basis,an experimental prototype is built for experimental research.The results show that the converter can be operated in both forward and reverse directions,the switches on the inverting side can be turned on at zero voltage,the rectifiers can be turned off at zero current,and the width can be realized.Range voltage regulation.