开关电源基础知识介绍（完整版）实用资料(可以直接使用，可编辑完整版实用资料，欢迎下载）开关电源基础知识介绍电源向负载R输出一个脉冲宽度为Toff,幅度为0的脉冲电压。这样,4反激变换器正激变换器反激框图2021-3-14PFC简介二合一电源板框图2021-3-14思考与讨论？为什么一般情况下交流低压输入时器件温升更高？为什么交流高压输入时待机功耗与漏电流更高？整机绝缘耐压测试NG，主要问题可能是？整机接地电阻测试NG，主要问题可能是？整机开机无24V输出，24V输出线材拔除后重启电源，24V输出正常，能否说明电源板无异常？2021-3-1421谢谢2021-3-1422Jack:No.I'mgoingtoAustralia.IwenttoJapantwoyearsago.A.Howlonghaveyoubeenhere?B.Whenisyourholiday?C.WhenareyouleavingforAustralia?D.Howlongdoyouplantostayhere?66.Mary________passingtheentranceexamination.A.succeededB.succeededinC.succeedsinD.succeeds67.Tellthechildnottodrink_______water.A.boiledB.boilC.boilingD.boils68.iset_________tomorrowonmyjourneytoAmerica.A.onB.upC.toD.out69.Theshopownerwould_______hismoneyeveryday.A.countB.countforC.countoutD.counting70.Theoldladydevotedherlifetime_______thehomelesschildren.A.tohelpB.tohelpingC.helpingD.forhelp答案:61-70DAACBBCDAB71.Tom:Wouldyoulikemetowateryourplantswhileyou'reonyourholiday?Joe:________A.Noproblem.Iwasmorethangladtodoit.B.Iappreciateit,butI'malreadyfinishedwateringthem.C.Thanksforofferingyourhelp,butmybrother'sgoingtodoit.D.Certainlywateringplantsismyfavoritepastime.72.--Don'tyouthinkit'sgoingtorainovertheweekend?--_______.A.Idon'tbelieveB.Idon'tbelieveitC.IbelievenotsoD.Ibelievenot73.IknewIshouldnotacceptanythingfromsuchapersonbutIfounditdifficulttoturndownhis___.A.planB.offerC.suggestionD.request74.--Doyoumindmytakingthisseat?--________.A.Yes,sitdownpleaseB.No,ofcoursenotC.Yes,takeitpleaseD.No,youcan'ttakeit75.HowIenvyyou_______yourgoodluck!A.inB.ofC.toD./76.Thiseventwasratherunusual,________?A.isitB.isn'titC.wasitD.wasn'tit77.Wehave_______booksinourlibrary.A.plentyofB.greatmanyC.agreatdealofD.greatnumberof78.Thepolicesawthewoman_______abusand_______ataxi.A.getoff…getonB.geton…getoffC.getoff…getintoD.geton…getinto79.Doyoumind______howyousucceed?A.ifIgoandseeB.ifIgoseeingC.mygoingandseeD.mygotosee80.Theboywouldhavedied,_______onhimw