欢迎来到天天文库
浏览记录
ID:56960371
大小:906.50 KB
页数:37页
时间:2020-07-22
《缓冲电路参数选取课件.ppt》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、Chapter27:SnubberCircuits27-1FunctionandTypesofsnubberCircuits27-2DiodesSnubber27-3SnubberCircuitsforThyristors27-4NeedforSnubberswithTransistors27-5Turn-offSnubber27-6Overvoltagesnubber27-7Turn-onSnubber27-8SnubbersforBridgeCircuitConfigurations27-9GTOSnubberConsiderations27-1OverviewofSnubberC
2、ircuitsforHard-SwitchedConvertersFunction:Protectsemiconductordevicesby:Limitingdevicevoltagesduringturn-offtransientsLimitingdevicecurrentsduringturn-ontransientsLimitingtherate-of-rise(di/dt)ofcurrentsthroughthesemiconductordeviceatdeviceturn-onLimitingtherate-of-rise(dv/dt)ofvoltagesacrossthe
3、semiconductordeviceatdeviceturn-offShapingtheswitchingtrajectoryofthedeviceasitturnson/offTypesofSnubberCircuits1.UnpolarizedseriesR-Csnubbers•Usedtoprotectdiodesandthyristors2.PolarizedR-Csnubbers•Usedasturn-offsnubberstoshapetheturn-offswitchingtrajectoryofcontrolledswitches.•Usedasovervoltage
4、snubberstoclampvoltagesappliedtocontrolledswitchestosafevalues.•Limitdv/dtduringdeviceturn-off3.PolarizedL-Rsnubbers•Usedasturn-onsnubberstoshapetheturn-onswitchingtrajectoryofcontrolledswitches.•Limitdi/dtduringdeviceturn-on27-2NeedforDiodeSnubberCircuit1ThecauseofovervoltagesTheovervoltagesocc
5、urduetothestrayorleakageinductanceLσinserieswiththediodeandthesnap-offofthediodereverserecoverycurrent.-+DfRsCsLsVdIoSwIrrdtVdLs=IottiDf(t)DiodevoltagewithoutsnubberdtLsdiLsvDf(t)diDfVd27-2NeedforDiodeSnubberCircuit2overvoltageprotectionIntroducingaRs-CssnubbercircuitIntroducingabaselinecapacita
6、nceCbaseandbaselineresistanceRbase,-+DfRsCsLsVdIoSw3PerformanceofR-CSnubberVmax=themaximumreversevoltageacrossthediode.ThereisanoptimumvalueofRs=Ropt=1.3RbasethatminimizesVmax.0123012VdVmaxRsRbaseRsIrrVdCs=CbaseRs,optRbase=1.34Implementation(2)Step-down,half-bridgeandfull-bridgeconvertersmaynotr
7、equireadiodesnubberifLσisminimizedbypropercircuitlayout.(1)Theconvertersthoseconsistofanisolationtransformerthatintroducedasubstantialleakageinductanceneeddiodesnubbercircuits.(3)Sinle-phaseline-frequencydiodeconverters.+Vs-
此文档下载收益归作者所有