全桥+LLC+谐振变换器研究

硕士学位论文全桥LLC谐振变换器研究RESEARCHONFULL-BRIDGELLCRESONANTCONVERTER黄贺哈尔滨工业大学2012年7月国内图书分类号：TM461.5学校代码：10213国际图书分类号：621.3密级：公开工学硕士学位论文全桥LLC谐振变换器研究硕士研究生：黄贺导师：贲洪奇教授申请学位：工学硕士学科：电气工程所在单位：电气工程系答辩日期：2012年7月授予学位单位：哈尔滨工业大学ClassifiedIndex:TM461.5U.D.C:621.3DissertationfortheMasterDegreeinEngineeringRESEARCHONFULL-BRIDGELLCRESONANTCONVERTERCandidate：HuangHeSupervisor：Prof.BenHongqiAcademicDegreeAppliedfor：MasterofEngineeringSpeciality：ElectricalEngineeringAffiliation：DepartmentofElectricalEngineeringDateofDefence：July,2012Degree-Conferring-Institution：HarbinInstituteofTechnology哈尔滨工业大学工学硕士学位论文-I-摘要在大功率二次电源中，LLC全桥变换器由于具备低应力，高效率，低电磁辐射等诸多技术优势，成为了研究热点。但LLC变换器的工作特性、可靠性对负载条件及工作频率所在区间较为敏感，在输入电压较低，负载由空载向满载切换的过程中，若谐振腔参数设计不合理，变换器易出现容性开关现象，烧毁变换器。为提高全桥LLC变换器的可靠性，本文在对LLC变换器的基本工作原理进行详细分析后，根据不同频率下的工作特性，将LLC变换器的工作频率区间划分为三部分，而后分别对不同工作区间内变换器稳态工作过程中的各个阶段进行详细描述。根据变换器结构特点进行简化分析后，得到全桥LLC变换器的等效原理电路，对该等效电路建立基波近似(FHA)建模，依据此模型，在推导出变换器的变压特性公式并做出曲线图后，详细的讨论了谐振腔参数对变换器变压特性的影响。对变换器在容性工作区域内的各个稳态工作阶段进行详细讨论后，找出了变换器的安全工作条件，进而推导出了谐振腔参数与该条件的关系式。在对变换器效率问题进行讨论时，分别对开关管损耗以及整流二极管损耗记性了详细的理论推导，得出了开关管损耗关于励磁电感量等参数的表达式，找到了谐振参数与变换器效率的联系。为找出LLC变换器在负载突变过程中出现暂态容性开通的具体工作机理，本文对变换器由轻载向重载切换时的工作过程进行了详细讨论，而后得出变换器输出端等效电路，对其进行暂态分析并推导出等效输出负载值的计算公式。以该公式作为参考，综合变换器软开关实现的条件、谐振腔参数与变换器工作特性的关系等因素，找出一套全桥LLC谐振变换器谐振腔参数的设计方法，达到提高变换器可靠性同时兼顾效率的目的。根据本文所述的设计方法，设计一台输出为48V/15A的LLC全桥变换器，使用saber对变换器参数进行仿真并制作了一台实验样机对理论进行了验证，昀终，实验结果证明了论文所提设计方法的可行性。关键词：LLC；全桥；软开关；可靠性；效率哈尔滨工业大学工学硕士学位论文-II-AbstractHavingtheadvantagesofthelowstress,highefficiencyandlowelectromagneticradiationinhighpowerDC/DCconverterapplying,full-bridgeLLCresonantconverterhasbecamearesearchhotspot.ButtheoperatingcharacteristicsandreliabilityoftheLLCconverterisverysensitivetotheloadconditionandtheoperatingfrequency.Especiallyinlowinputvoltagecircumstances，whenloadconditionischangedfromidletofull-load,theoperatingfrequencydecreasesrapidly,iftheparametersofresonantcavityarenotdesignedproperly,theconverterwillrunincapacitivemodeandburndownintheend.Inordertoimprovethereliability,thebasicworkingprincipleofthefull-bridgeLLCconverterisanalysedfirstly,accordingtotheintervalsthattheworkingfrequencyoftheconverterliesin,theworkphasesofconverteraredescribedindetailrespectively.Aftersimplifyingtheconverterstructure,theprinciplecircuitisobtainedandaFHAmodelisconstructed,withthatmodel,againformulaisderivedandasetofcurvesaredrawn,thentheinfluenceofthecavity’sparameterongainfeaturesoftheconverterareanalysedindetails.Afterdiscussingalltheworkingstageoftheconverterincapacitivemode,thesafeworkingrequirmentoftheLLCconverterisfound,thentherelationshipbetweenthatrequirmentandtheparametersoftheresonantcavityisgained.Indiscussingtheefficiencyoftheconverter,thelossoftheswithandtherectiferdiodeisanalysedindetail,thentheswitchlossformulawithrespecttomagnetizinginductnceisobtained,findingouttherelationshipbetweentheparametersoftheresonantcavityandtheefficiencyoftheconverter.Then,bydiscussingtheprocessingthattheloadconditonischangedfromidletofull-load,theoutputequivalentcircuitoftheconverterisachived,byapplyingtransientanalysisonthatcircuit,theformulaforcalculatingtheequivalentoutputloadvalueisderived.Takingtheformulaasadesignconsiderationandcombiningthefactorsofrequirementforsoft-switchingimplementationandtherelationshipbetweenparametersoftheresonantcavityandoperatingcharacteristicsoftheconverter，asetofdesignmethodsforfull-bridgeLLCresonantconverterresonatorparametersisfoundtoimprovethereliablityofconverterwhoseefficiencyisalsotakenintoaccount.Accordingtothedesignmethodpresentedinthisarticle,a48V/15ALLCfullbridgeconverterisdesigned,byusingthesabertosimulateandproducinganexperimentalprototype，finally，theoryisverfied.Keywords:LLC,Full-bridge,Soft-switching,realibility，efficiency哈尔滨工业大学工学硕士学位论文-III-目录摘要......................................................................................................................I ABSTRACT...........................................................................................................II 第1章绪论.......................................................................................................1 1.1课题背景与研究的目的和意义...............................................................1 1.2软开关技术发展概况介绍......................................................................2 1.2.1零电压移相全桥变换技术......................................................................2 1.2.2零电流移相全桥变换技术......................................................................3 1.2.3有源箝位技术.........................................................................................3 1.2.4零电压零电流移相全桥变换技术..........................................................4 1.2.5LLC谐振变换技术.................................................................................5 1.3本文的主要内容.....................................................................................6 第2章变换器稳态能量传输过程分析.................................................................7 2.1引言.......................................................................................................7 2.2变换器主电路拓扑结构.........................