LLC谐振变换器效率优化设计

Optimal Efficiency Design of LLC Resonant Converters

由于LLC谐振变换器拓扑具有高效率和高功率密度的优势,广泛应用于DC-DC变换器场合。但是由于谐振过程分析的复杂性,关于谐振回路参数的选择,LLC变换器缺少一种明确的设计方法。在基于工作模态以及谐振腔电流分析的基础上,提出峰值增益配置的优化设计法。通过该方法,变换器可以在要求增益的范围内将导通损耗最小化。搭建一台400 W、400 V输出,25～38 V输入的LLC变换器。为验证本文优化设计方法的正确性,在减少谐振电容的同时采用搜寻的方法依据优化原则重新选择LLC的其他参数,实验结果表明,提出的优化设计法具有更好的性能,样机最高效率超过98%。

The LLC resonant converter topology is widely used in DC-DC conversion applications due to its advantages in achieving high efficiency and high power density.However,due to the complexity in the analysis,the converter lacks a clear design guideline on the selection of resonant tank parameters.In this paper,an optimization method is developed based on the operation mode analysis and peak gain placement.Following this approach,the converter can minimize the conduction losses while maintaining the required gain range.A 400 W,400 V output and 25～38 V input LLC converter is built using the proposed method,As a comparison,the conventional searching method is used to reselect the LLC parameters for the same specifications,and the experimental results show that the optimal design has better performance and peak efficiency can reach over 98%.