Research On Reconfigurable DC-DC Resonant Converter With Wide Gain Range

While the rapid advancement of the global industrialization process and the continuous increase of social productivity,problems such as air pollution,water pollution and fossil fuel depletion have become increasingly prominent.Therefore,the exploration and research of new energy systems such as photovoltaic power generation systems and electric vehicle systems are increasingly favored by scholars.However,photovoltaic power generation is susceptible to environmental influences to produce a wide range of output voltages,which affects the DC bus voltage;There is also a wide-range voltage change during the charging process of electric vehicle batteries.Based on the problem of the wide-range voltage change,a recomfigurable DC-DC resonant converter is proposesd to achieve high efficiency and wide voltage gain in this paper.Based on the analysis of the related research on the wide-gain resonant converter of the recomfigurable structure transformation,this paper adopts a combined DC-DC resonant topology structure constructed by two sets of LLC resonant networks and three sets of rectifier bridge arms.Through the combination of the primary side resonant network and the collocation of the secondary side rectifier bridge arms,the resonant converter can realize four circuit working modes and the effect of wide gain.Each working mode can be equivalent to an LLC resonant circuit,inheriting the advantages of LLC resonant circuit such as high frequency,soft switching and effective use of leakage inductance.In addition,the four operating modes have the same resonant frequency operating point and similar operating frequency range,which facilitates the design of magnetic components and frequency modulation control of the overall circuit.The analysis of the structure transformation,equivalent circuit network and gain model of four working modes is completed in detail for the proposed circuit.The influence of resonance parameters on the gain and the soft switching of each mode are analyzed and discussed.Finally,an experimental prototype with a maximum power of 3.3k W,input 400 V and a wide range of voltages of 75V-450 V is designed.The experimental results indicate that a wide voltage range gain can be achieved and the switches can realize ZVS in the full operating range of the proposed recomfigurable DC-DC resonant converter.