LLC电路的交错并联技术研究

硕士学位论文LLC电路的交错并联技术研究RESEARCHOFLLCCIRCUITININTERLEAVEANDPARALLELTECHNOLOGY王金录哈尔滨工业大学2011年12月国内图书分类号：TM464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LLC电路的交错并联技术研究硕士研究生：王金录导师：和军平副教授申请学位：工学硕士学科：电气工程所在单位：深圳研究生院答辩日期：2011年12月授予学位单位：哈尔滨工业大学ClassifiedIndex:TM464U.D.C:621.3DissertationfortheMasterDegreeinEngineeringRESEARCHOFLLCCIRCUITININTERLEAVEANDPARALLELTECHNOLOGYCandidate：WangJinLuSupervisor：Asso.Prof.HeJunpingAcademicDegreeAppliedfor：MasterofEngineeringSpeciality：ElectricalEngineeringAffiliation：ShenzhenGraduateSchoolDateofDefence：December,2011Degree-Conferring-Institution：HarbinInstituteofTechnology哈尔滨工业大学工学硕士学位论文-I-摘要对PWM调制的开关电源拓扑，只要采取适当的控制方法调节占空比，就可以实现良好的均流，但对采用PFM控制的LLC电路来说，通过调频方法不容易实现交错控制的均流，而调占空比又会失去软开关的优点，因此均流成为交错并联LLC设计的一大难点。研究交错并联LLC负载电流分配不均的原因和解决方法成为本课题的重点，本文主要研究内容如下：首先，对输入端串联、并联两种交错并联LLC的拓扑结构进行时域的仿真分析，总结两种拓扑结构的优缺点。针对影响并联LLC负载分配不均衡的主要因素——谐振元件的误差，进行了仿真分析。当谐振参数存在差异时，应用Mathcad绘出单相LLC的增益曲线，并在此基础上分析了输入端串联结构自动均流的原因。最终确定了输入端电容串联附加自动均流电路的拓扑结构形式。其次，为了分析谐振参数差异对交错并联LLC频域性能的影响，方便控制环路的设计，在单相LLC模型的基础上，得到交错并联LLC的小信号模型。在得出主电路的传递函数后，依据主电路时域仿真的结果，通过Saber仿真软件对谐振腔中交流量进行傅里叶级数分解，得出谐振腔中电压电流的基波分量，再应用Mathcad软件可绘出Bode图。通过Bode图分析了谐振参数的具体影响，发现谐振参数对控制系统影响不大，交错并联LLC的控制系统与单相LLC的相似，可以应用PI补偿网络提高系统的稳定性。再次，根据并联LLC负载不平衡原因的分析，对谐振参数的选取进行优化处理，进一步提升了电路的均流能力，并且提出了均流电路电感和电容参数的计算方法，完善了均流方案的整体设计。最后，完成硬件电路设计，实现了数字交错控制，并对样机进行了实测。实验包括开关管驱动、稳态和动态工作状态、环路频率响应。实验结果表明，实现了交错控制，均流效果良好。在减小了输出滤波电容容值的情况下，输出纹波电压满足标准要求，证明了本文所提理论分析的正确性及均流方法的有效性。关键词：交错并联；均流；LLC；负载不平衡；数字控制哈尔滨工业大学工学硕士学位论文-II-AbstractForgeneralPWMcontrolcircuittopology,aslongastherightcontrolmethodisused,withtheadjustmentofdutythecurrentsharingcanbeachieved,butfortheLLCcircuitwiththePFMcontrol,itisunabletorealizecurrentsharingthroughcontrollingthefrequency,andifthedutyisadjusted,theadvantagesofsoftswitchwilllost,socurrentsharingbecomeabigdifficultyofdesignofinterleavedLLC.SothereasonandthesolutionthattheparrallelLLCcan’trealizecurrentsharingbecomethefocusofthistopic.Specificcontentasfollows:Firstly,twotopologicalstructurethattheinputofinterleavedLLCisseriesandparallelismadethesimulationinthetimedomain,andtheadvantagesanddisadvantagesoftwokindsoftopologicalstructurearesummarized.AccordingtothemainfactorswhichinfluenceparallelLLCcircuitonloaddistribution—theresonantcomponentserror,thesimulationanalysisisdone,usingmathcadthegaincurveofsingle-phaseLLCisdrew,astheresonantparameterserrorvary,theimbalanceofreasonisresearched,alsotheprinciplethatseriesstructureintheinputcanrealizecurrentsharingisanalyzed.Thetopologystructureisdeterminedtobethestructureofseriesintheinputwiththecurrentsharingcircuit.Secondly,inordertoanalysistheinfluencethattheresonantparameterserrorbrighttheinterleavedLLCinthefrequencydomainandgettheconvenientoftheclosedloopdesignandanalysis,onthebaseofsingle-phaseLLCmodeling,thesmallsignalmodelofinterleavedLLCmodelingisgot,afterthetransferfunctionofmaincircuitisgot,accordingtothemaincircuitsimulationresultsinthetimedomain,usingthesabersimulationsoftwaretheexchangequantityinresonancecavityismadeFourierdecomposition,thevoltageandcurrentoftheresonantcavityinthebasewavearegotten,atthelastusingthemathcadsoftwarethebodefigureisdrew,withthegraphicstheeffectsoftheresonantparametersisanalysised,theeffectoftheresonantparametersonthecontrolsystem.Thirdly,accordingtotheanalysisoftheresonthatparallelLLCcann’tsharethecurrent,theselectionoftheresonanceparametershouldbeoptimized.Andtheparameterselectionmethodoftheinductanceandcapacitanceinthesharecurrentcircuitareputforward.Theschemeofcurrentsharingisrealized.Finally,Thehardwarecircuitdesigniscompleted,andusingDSPthedigitalinterleavedcontrolisrealized.theprototypeistested,theexperimentalwaveformmainlyincludesthedriverswaveformsoftheswitchtube,steadystateanddynamicstatewaveform,loopfrequencyresponse,throughtotheanalysisofexperimentalresultsshowthattheinterleavedcontrolisimplemented,theeffectofcurrent哈尔滨工业大学工学硕士学位论文-III-sharingarealsoverygood,alsothecorrectnessofthetheoryanalysisandthevalidityofthecurrentsharingmethodareproved.Keywords:interleave，currentsharing，LLC，unbalancedload，digitalcontrol哈尔滨工业大学工学硕士学位论文-IV-目录摘要..........................................................................................................................IABSTRACT................................................................................................................II第1章绪论.............................................................................................................11.1课题研究目的和意义................................................................................11.2LLC与并联均流技术的相关研究及发展概况...........................................11.3主要研究内容及章节安排.........................................................................6第2章主电路拓扑的选择及时域分析...................................................................82.1交错并联LLC的原理...............................................................................82.1.1交错意义及优点.........................................................................................82.1.2输入端并联结构交错并联LLC技术.......................................................9