全桥软开关LLG变换器模型与设计

摘要

Technology trends in modern DC/DC converter design is high frequency,efficiency and high power density.According to circuit topology,the mathematical model for LLC resonant full-bridge converter was presented.Furthermore,the relationship between voltage gain and load was deduced.On the basis of conversion relations between the best conversion efficiency and wide scope of load changes,circuit parameters were confirmed according to the model.A LLC resonant full-bridge converter with soft switching was designed.The simulation and experiment results show that the transfer efficiency can reach to 94％ from light to full load.Switch frequency and power density has been improved up to MHz-level and 2.4 x 107 W/m3,respectively.The results ultimately verify the correctness of the model and parameter deduction.%现代DC/DC变换器的发展趋势是高频率、高效率和高功率密度.基于电路拓扑结构,提出了全桥LLC谐振变换器的数学模型,推导了电压增益与负载的关系.基于最优转换效率和宽负载变化范围的转换关系,确定了谐振电路参数,并设计了一款全桥软开关LLC谐振变换器.仿真与实验结果表明,该设计从轻载到满载范围内效率均达到94％以上,开关频率提高到了兆赫兹级,功率密度达到2.4×107 W/m3,验证了模型的正确性.