基于临界模式Boost电路与LLC谐振电路的单级交直变换器

摘要

A single-stage AC-DC converter based on the boundary conduction mode( BCM )boost circuit and the LLC resonant circuit is proposed in the paper. The input voltage is divided into two parts,each of which forms a BCM boost circuit by sharing one switch of the LLC resonant circuit. Because of the integration,the proposed AC-DC converter is with less components and low cost. At the same time,the boost circuit works in the BCM mode so that the power factor correction function is realized. The integration of the switches does not affect the soft-switching characteristics of the half bridge LLC resonant circuit,so that the converter switching losses is decreased and the converter efficiency is increased. A 100 W prototype is built to prove the analysis,the power factor(PF)is 0. 975,the total harmonic distortion(THD)is 21. 5% satisfying the IEC 63000—3—2 standard, and its efficiency is 90. 8%.%提出一种基于临界模式Boost电路与LLC谐振电路的单级交直变换器，由于其通过输入分压与LLC谐振电路的两个开关管各形成一个临界模式的Boost电路，实现了开关管的集成，降低了系统成本。同时Boost电路工作在临界模式，实现了功率因数校正作用，开关管的集成并没有改变LLC半桥谐振电路的软开关特性，降低了变换器中开关元件的损耗，在一定程度上提高了变换器效率。通过一100 W实验样机的实验验证可知，系统满载时功率因数高达0.975，总谐波失真（ THD）为21.5豫并满足IEC 63000—3—2的标准，效率为90.8豫。