简介:本文提出一种新型的Boost-Buck变换器,该变换器具有输入输出电流连续、输出电压可调范围大等优点。由于该变换器的输入电流连续,所以适合于功率因数校正电路,且其实现较为简单。该变换器的输出电压可调范围大,可以大于(或小于)输入电压,这就很好地克服了传统Boost变换器输出电压必须大于输入电压的缺点。理论分析、仿真和实验均验证了该变换器的实用性。
简介:Anovelcontrolschemeispresentedbyusingsliding-modecontrolforboostconverteroperatingincontinuousconductionmode(CCM).Althoughthenon-idealswitchingconditionandphysicalconstraintofthecontrolareconsideredonthebaseofequivalentcontrol,theschemeisstillsimple.Bymodifyingthesliding-modcerrorsineachswitchingperiod,thesteady-stateerrorsandchatteringcanbesubstantiallyreduced.Simulationresultsconfirmthetheoreticalanalysisandshowtheimprovementoftheconverter’sstart-upbehaviorandlowsensitivitytoexternalperturbation.
简介:Thezero-voltagequasi-resonantboostswitchingDC-DCconverterhasbeeninves-tigatedbyusingthetimeaveragingequivalentcircuitapproachofperiodicallyswitchinglinearnetworks.TheDCsteadystateandACsmallsignalcharacteristicsoftheconverterarealsogiven.
简介:实验评估了600V,4A碳化硅(SiC)肖特基二极管(英飞凌,SDP04S06)的性能。作为一种重点的应用,作者考虑选用一种300W,按平均电流模式控制的Boost功率因数校正器(PFC)。作者测量了采用该型号SiC肖特基二极管和采用两种超快、软恢复的硅功率二极管(RURD460和目前正被列入的STTH5R06D)制成的整机的效率、开关损耗、二极管损耗和电磁干扰(EMI)等特性。本文比较了这些结果,特别是定量地考察了SiC二极管提供的恢复电流的减小对该变换器行为的这些关键参数的影响。基于试验结果,本文表明在功率因数校正器设计中,采用SiC二极管只是在高开关频率时才是合算的。
简介:PURPOSE:Toreviewtheefficacyandpatternsoffailureinaverage-riskmedulloblastomapatientstreatedwithconcurrentchemotherapyandreduced-dosecranialspinalirradiationandaconformaltumorbedboost.METH-ODSANDMATERIALS:Thirty-threepatientswithaveragerisk(definedas<==1.5cm(2)ofresidualtumorafterresection,age>3years,andnoinvolvementofthecerebrospinalfluidorspine)medulloblastomawerediagnosedatourinstitutionbetweenJanuary1994andDecember2001.Theywereenrolledinaninstitutionalpilot