拓扑变换型LLC-C谐振软开关直流变换器

A Topology Morphing LLC-C Resonant Soft-Switching DC-DC Converter

提出一种拓扑变换型LLC-C谐振软开关直流变换器。它是将两种简单谐振结构相结合,利用辅助开关管控制变换器的等效电路结构。在额定工作条件下,变换器工作在LLC模式,实现高效率运行;在输入电压偏高时,自动切换至LCCL模式,以在获得较宽电压增益范围的同时仍维持较高效率。进一步地,对电路的损耗分布情况进行了分析计算,选取两种模式效率曲线相交处为模式切换最佳点,为变换器工作模式设计提供了理论依据。最后,为了验证所述变换器原理的可行性,给出了相应的实验结果:输入电压从110V变化至400V的过程中,输出电压始终维持在200V,对应的电压增益从1.8至0.5;变换器效率始终维持在高于90%的较高值,最高可达97.5%。变换器这种在宽增益范围维持高效率的特点使其非常适用于新能源发电等对电压范围和效率有较高要求的应用场合。

In this paper,a topology morphing LLC-C resonant soft-switching DC-DC converter is proposed.It successfully integrates two simple resonant structures together and adopts auxiliary switches to regulate the equivalent circuit architectures.Under the rating condition,the converter operates as LLC circuit for high-efficiency operation;when the input voltage is relatively high,the converter enters the LCCL mode automatically so that wide voltage gain range as well as relatively high efficiency is achieved.Furthermore,the loss distribution issue is analyzed and calculated.The intersection point of efficiency curves in the two circuit modes is selected as the optimal switching point of the mode transformation,which provides the foundation for the operating mode design.Finally,in order to verify the principle feasibility of the proposed converter,the experimental results are provided.When the input voltage varies from 110V to 400V,the output voltage is maintained at 200V constantly,and the corresponding voltage gain is from 1.8 to 0.5.Meanwhile,the converter efficiency is above 90%,up to 97.5%.The high efficiency of the converter in wide gain range makes it highly suitable for the renewable energy generation applications,where voltage range and efficiency issues are always required strictly.