Buck-LLC变换器三环定频控制与同步整流技术  

The Three-loop Constant Frequency Control for Buck-LLC Converter and Synchronous Rectification Technology

作　　者：刘闯 张兴[1] 赵文广 杜成孝 

机构地区：[1]合肥工业大学,电气与自动化工程学院,安徽合肥230009 [2]兴安技术师范大学,电力电子学院,越南兴安160000

出　　处：《电力电子技术》2018年第1期5-7,17,共4页Power Electronics

基　　金：国家重点研发计划(2016YFB0900300)

摘　　要：LLC谐振变换器因其高效率、高功率密度等优点,在中小功率DC/DC变换器中被广泛使用。但当LLC谐振变换器工作于变频状态时,谐振腔中的磁性元件设计困难;当工作于定频工作状态时,LLC谐振变换器允许的输入电压范围较窄。Buck-LLC变换器在LLC谐振变换器前增加了Buck变换器,可使LLC谐振变换器工作于开环的定频工作模式,有利于磁性元件的设计,前级的Buck变换器可使输入电压范围变宽。针对Buck-LLC谐振变换器,采用三环定频的控制方法,使变换器具有较宽的电压调节范围和较强的抗负载扰动能力。为进一步提高变换器效率,在LLC谐振变换器次级采用了同步整流技术。为验证所得结论,搭建了一台300 W的Buck-LLC变换器原理样机,样机工作效率达到96%。LLC resonant conveners are widely used in the low and medium power DC/DC converters due to its high efficiency and high power density.However,at variation frequency operation state,the LLC resonant converter faces difficultly to design the cavity of the magnetic core element.Meanwhile,it only allows a narrow input voltage range when operates at the fixed frequency operation state.A Buek-LLC converter,which is derived by adding a Buck con- verter in front of the LLC resonant converter, has been investigated in this work.The Buck-LLC converter is possible to operate at the open-loop fixed frequency mode and facilitate for design of the magnetic core element.In addition, with the help of the first converter stage-Buck converter based, the Buck-LLC converter can work in the wide input voltage range.Based on Buck-LLC converter,three-loop constant frequency control has been proposed,which has a wide voltage regulation range and with the ability to copy with the disturbance load.To further improve the efficiency of the converter,the synchronous rectification technology is applied in the secondary-side of LLC converter.In experiment, a 300 W Buck-LLC converter prototype is built, and the working efficiency of the prototype reaches to 96%.

关 键 词：变换器 三环定频控制 同步整流技术 

分 类 号：TM46[电气工程—电器]