全桥LLC谐振变换器研究
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论文题目：全桥LLC谐振变换器研究 专 业：电力电子与电力传动 (签名) 刘树林 摘 要 (签名)
硕 士 生：文美娟 指导教师：张刚
随着开关电源向高频、高效和高功率密度方向的发展，传统的硬开关在应用中出现 了很多问题。为解决这些问题，软开关技术应运而生。谐振型开关变换器作为软开关的 一种，具有工作频率高、损耗小、效率高、体积小等优点。而 LLC 谐振型开关变换器 以其兼具能够在全负载范围内实现原边开关管的 ZVS 开通，整流二极管的 ZCS 关断的 特点和便于磁集成、 输入电压范围宽等优势， 在高频开关领域获得了广泛的关注和应用。 本文首先研究了谐振型开关变换器的发展及其分类，并对各种谐振变换器的优缺点 进行了比较和总结。在此基础上对全桥 LLC 谐振变换器的工作原理进行了详细分析， 同时还分析了其频率特性、空载特性以及短路特性，指出了变换器各参数对其工作情况 的影响。其次，采用 MC33067 作为全桥 LLC 谐振变换器的主要控制芯片，探讨了变换 器主电路以及驱动电路的详细设计过程，其中包括主开关管、整流二极管、输出滤波电 容等元器件的参数计算及选型，着重给出了谐振电感、谐振电容等谐振元件以及主变压 器、驱动变压器等磁性元件的选择依据和设计方法。最后，采用 Saber 软件对该变换器 主电路进行了仿真分析并搭建了实验样机，详细分析了实验过程中遇到的几个问题，如 变换器不能工作在感性状态、工作频率不可线性变化，并给出了相应的解决方案。 本文设计了一台 500W 的全桥 LLC 谐振变换器实验样机。通过对样机的测试得到 了变换器开关管的驱动波形、谐振电流以及输出纹波电压等波形。经过对这些波形的分 析可知，文中的理论研究和设计方法都是合理可行的。
关 键 词：全桥 LLC 谐振变换器，ZVS，空载特性，MC33067 研究类型：应用研究
Subject Specialty Name
：Research on Full Bridge LLC Resonant Converter ：Power Electrics&Power Drives ：Wen Meijuan Liu Shulin (Signature) (Signature)
this paper are reasonable and feasible.
Key words：Full bridge LLC resonant converter, ZVS, No load characteristic, MC33067 Thesis ：Application Research
Instructor ：Zhang Gang
ABSTRACT
With the development of the switching power supply toward the high frenquency, efficiency and power density, the traditional hard switching appears a lot of problems in the application. To solve these problems, the soft switching technology comes into being. As a kind of soft switching, the resonance switching converter has the advantages of high frequency, low loss, high efficiency, small size, and so on. As the LLC resonant power converter can achieve both ZVS of the primary switch and ZCS of the rectifier diode in full load range and have the advantages of easy integrating, wide input voltage range and so on, it gets wide attention and application in the high frequency switching field. Firstly, the basic classification of resonant converters and the advantages and disadvantages of various resonant converters are analyzed in this paper. On this basis, not only the working principle but also the frequency characteristic, no-load characteristic and short-citcuit characteristic of the converter are discussed in detail. And the impacts of the parameters on the converter are pointed out. In addition, the high performance resonant mode controller MC33067 is selected as the main control chip of the converter. The detailed design process of the converter’s main and drive circuits are investigated, including the parameters’ calculation and selection of main switch, rectifier diode and output filter capacitor. Especially, the selecting basis and design method of the resonance elements (e.g. the resonant inductor, capacitor and so on) and magnetic elements (such as the main transformer and drive transformer, etc.) are given. Finally, Saber software is adopted to simulate and analyze the main circuit of the converter. An experimental prototype is set up, and some problems, e.g., the converter can’t work on the inductive state and the operating frequency can’t be linear change, in the experiment are analyzed in detail and the corresponding solutions are given. A 500W full-bridge LLC resonant converter prototype is designed in this paper. Waveforms of switch, resonant current and the output ripple voltage can be obtained according to the prototype test. It proves that the theoretical research and design method in
目 录
目 录Biblioteka Baidu
1 绪论 .......................................................................................................................... 1 1.1 本课题研究背景及意义 ................................................................................................1 1.2 国内外研究动态和发展趋势 ........................................................................................2 1.2.1 谐振型开关变换器的研究动态 .............................................................................2 1.2.2 LLC 谐振变换器的发展趋势 .................................................................................9 1.3 本文的主要研究内容 ..................................................................................................10 2 全桥 LLC 谐振变换器的原理及特性 ........................................................................ 12 2.1 全桥 LLC 谐振变换器的主电路结构 .........................................................................12 2.2 全桥 LLC 谐振变换器的等效电路及工作区域 ..........................................................13 2.2.1 全桥 LLC 谐振变换器的等效电路 ......................................................................13 2.2.2 全桥 LLC 谐振变换器的工作区域 ......................................................................16 2.3 全桥 LLC 谐振变换器工作原理分析 .........................................................................19 2.3.1 变换器在 fm<f<fr 时工作原理 ...............................................................................19 2.3.2 变换器在 f=fr 时工作原理 ....................................................................................24 2.3.3 变换器在 f>fr 时工作原理 ....................................................................................25 2.4 全桥 LLC 谐振变换器的特性分析 .............................................................................28 2.4.1 频率特性 ..............................................................................................................28 2.4.2 空载特性 ..............................................................................................................30 2.4.3 短路特性 ..............................................................................................................32 2.5 本章小结 .....................................................................................................................32 3 全桥 LLC 谐振变换器设计 ...................................................................................... 34 3.1 全桥 LLC 谐振变换器电路组成框图 .........................................................................34 3.2 主电路设计 .................................................................................................................35 3.2.1 主变压器设计 ......................................................................................................35 3.2.2 谐振电容 Cr 选取 .................................................................................................37 3.2.3 谐振电感 Lr 选取..................................................................................................38 3.2.4 励磁电感 Lm 选取 ................................................................................................38 3.2.5 主开关管的选用...................................................................................................39 3.3 整流滤波电路设计 ......................................................................................................41 3.3.1 整流电路拓扑选择...............................................................................................41 3.3.2 输出整流二极管的选择 .......................................................................................42
硕 士 生：文美娟 指导教师：张刚
随着开关电源向高频、高效和高功率密度方向的发展，传统的硬开关在应用中出现 了很多问题。为解决这些问题，软开关技术应运而生。谐振型开关变换器作为软开关的 一种，具有工作频率高、损耗小、效率高、体积小等优点。而 LLC 谐振型开关变换器 以其兼具能够在全负载范围内实现原边开关管的 ZVS 开通，整流二极管的 ZCS 关断的 特点和便于磁集成、 输入电压范围宽等优势， 在高频开关领域获得了广泛的关注和应用。 本文首先研究了谐振型开关变换器的发展及其分类，并对各种谐振变换器的优缺点 进行了比较和总结。在此基础上对全桥 LLC 谐振变换器的工作原理进行了详细分析， 同时还分析了其频率特性、空载特性以及短路特性，指出了变换器各参数对其工作情况 的影响。其次，采用 MC33067 作为全桥 LLC 谐振变换器的主要控制芯片，探讨了变换 器主电路以及驱动电路的详细设计过程，其中包括主开关管、整流二极管、输出滤波电 容等元器件的参数计算及选型，着重给出了谐振电感、谐振电容等谐振元件以及主变压 器、驱动变压器等磁性元件的选择依据和设计方法。最后，采用 Saber 软件对该变换器 主电路进行了仿真分析并搭建了实验样机，详细分析了实验过程中遇到的几个问题，如 变换器不能工作在感性状态、工作频率不可线性变化，并给出了相应的解决方案。 本文设计了一台 500W 的全桥 LLC 谐振变换器实验样机。通过对样机的测试得到 了变换器开关管的驱动波形、谐振电流以及输出纹波电压等波形。经过对这些波形的分 析可知，文中的理论研究和设计方法都是合理可行的。
关 键 词：全桥 LLC 谐振变换器，ZVS，空载特性，MC33067 研究类型：应用研究
Subject Specialty Name
：Research on Full Bridge LLC Resonant Converter ：Power Electrics&Power Drives ：Wen Meijuan Liu Shulin (Signature) (Signature)
this paper are reasonable and feasible.
Key words：Full bridge LLC resonant converter, ZVS, No load characteristic, MC33067 Thesis ：Application Research
Instructor ：Zhang Gang
ABSTRACT
With the development of the switching power supply toward the high frenquency, efficiency and power density, the traditional hard switching appears a lot of problems in the application. To solve these problems, the soft switching technology comes into being. As a kind of soft switching, the resonance switching converter has the advantages of high frequency, low loss, high efficiency, small size, and so on. As the LLC resonant power converter can achieve both ZVS of the primary switch and ZCS of the rectifier diode in full load range and have the advantages of easy integrating, wide input voltage range and so on, it gets wide attention and application in the high frequency switching field. Firstly, the basic classification of resonant converters and the advantages and disadvantages of various resonant converters are analyzed in this paper. On this basis, not only the working principle but also the frequency characteristic, no-load characteristic and short-citcuit characteristic of the converter are discussed in detail. And the impacts of the parameters on the converter are pointed out. In addition, the high performance resonant mode controller MC33067 is selected as the main control chip of the converter. The detailed design process of the converter’s main and drive circuits are investigated, including the parameters’ calculation and selection of main switch, rectifier diode and output filter capacitor. Especially, the selecting basis and design method of the resonance elements (e.g. the resonant inductor, capacitor and so on) and magnetic elements (such as the main transformer and drive transformer, etc.) are given. Finally, Saber software is adopted to simulate and analyze the main circuit of the converter. An experimental prototype is set up, and some problems, e.g., the converter can’t work on the inductive state and the operating frequency can’t be linear change, in the experiment are analyzed in detail and the corresponding solutions are given. A 500W full-bridge LLC resonant converter prototype is designed in this paper. Waveforms of switch, resonant current and the output ripple voltage can be obtained according to the prototype test. It proves that the theoretical research and design method in
目 录
目 录Biblioteka Baidu
1 绪论 .......................................................................................................................... 1 1.1 本课题研究背景及意义 ................................................................................................1 1.2 国内外研究动态和发展趋势 ........................................................................................2 1.2.1 谐振型开关变换器的研究动态 .............................................................................2 1.2.2 LLC 谐振变换器的发展趋势 .................................................................................9 1.3 本文的主要研究内容 ..................................................................................................10 2 全桥 LLC 谐振变换器的原理及特性 ........................................................................ 12 2.1 全桥 LLC 谐振变换器的主电路结构 .........................................................................12 2.2 全桥 LLC 谐振变换器的等效电路及工作区域 ..........................................................13 2.2.1 全桥 LLC 谐振变换器的等效电路 ......................................................................13 2.2.2 全桥 LLC 谐振变换器的工作区域 ......................................................................16 2.3 全桥 LLC 谐振变换器工作原理分析 .........................................................................19 2.3.1 变换器在 fm<f<fr 时工作原理 ...............................................................................19 2.3.2 变换器在 f=fr 时工作原理 ....................................................................................24 2.3.3 变换器在 f>fr 时工作原理 ....................................................................................25 2.4 全桥 LLC 谐振变换器的特性分析 .............................................................................28 2.4.1 频率特性 ..............................................................................................................28 2.4.2 空载特性 ..............................................................................................................30 2.4.3 短路特性 ..............................................................................................................32 2.5 本章小结 .....................................................................................................................32 3 全桥 LLC 谐振变换器设计 ...................................................................................... 34 3.1 全桥 LLC 谐振变换器电路组成框图 .........................................................................34 3.2 主电路设计 .................................................................................................................35 3.2.1 主变压器设计 ......................................................................................................35 3.2.2 谐振电容 Cr 选取 .................................................................................................37 3.2.3 谐振电感 Lr 选取..................................................................................................38 3.2.4 励磁电感 Lm 选取 ................................................................................................38 3.2.5 主开关管的选用...................................................................................................39 3.3 整流滤波电路设计 ......................................................................................................41 3.3.1 整流电路拓扑选择...............................................................................................41 3.3.2 输出整流二极管的选择 .......................................................................................42