A Mathematical Guideline for Designing an AC-DC LLC Converter with PFC

Although LLC topology has been applied to AC-DC power supplies as a Power Factor Correction (PFC) converter in the literature, there is no publications present intuitive equations that simplify LLC designing in order to meet the PFC gain requirements. In this paper, a mathematical design guideline is derived for LLC PFC converter applications, proving that by carefully designing the resonant tank gain at parallel resonant frequency at the peak AC voltage higher than 1, its gain will meet the PFC requirement for other AC voltages and result in a successful single-stage PFC design with power factor over 0.99. The guideline is extended to offline wide input and output voltage LLC PFC applications. A 240-Watt prototype of a single-stage LLC LED driver with PFC has been built to verify the feasibility of the proposed design guideline.

使用PFC设计AC-DC LLC转换器的数学准则

尽管在文献中LLC拓扑已作为功率因数校正（PFC）转换器应用于AC-DC电源，但是没有出版物提供直观的方程式来简化LLC设计以满足PFC增益要求。 本文针对LLC PFC转换器应用推导了数学设计指南，证明了通过精心设计并联谐振频率下峰值交流电压高于1时的谐振回路增益，其增益将满足其他交流电压的PFC要求。 从而成功完成了功率因数超过0.99的单级PFC设计。 该指南扩展到离线宽输入和输出电压LLC PFC应用。 已构建具有PFC的单级LLC LED驱动器的240瓦原型，以验证所提出设计指南的可行性。