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ID:38420488
大小:104.00 KB
页数:12页
时间:2019-06-12
《电力电子及电力系统常用翻译》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、第一章电力电子技术Semiconductorswitchesareveryimportantandcrucialcomponentsinpowerelectronicsystems.theseswitchesaremeanttobethesubstitutionsofthemechanicalswitches,buttheyareseverelylimitedbythepropertiesofthesemiconductormaterialsandprocessofmanufacturing.在电力电子系统,中半导体开关是非常重要和关键部件。半
2、导体开关将要替换机械开关,但半导体材料的性质和生产过程严重限制了他们。1开关损耗SwitchinglossesPowerlossesinthepowerelectronicconvertersarecomprisedoftheSwitchinglossesandparasiticlosses.电力电子转换器的功率损耗分为开关损耗和寄生损耗theparasiticlossesaccountforthelossesduetothewindingresistancesoftheinductorsandtransformers,thedielectri
3、clossesofcapacitors,theeddyandthehysteresislosses.寄生损失的绕组电感器、变压器的阻力、介电损耗的电容器,涡流和磁滞损耗theswitchinglossesaresignificantandcanbemanaged.这个开关损耗是非常重要的,可以被处理。theycanbefurtherdividedintothreecomponents:(a)theon-statelosses,(b)theoff-statelossesandthelossesinthetransitionstates.他们可以分
4、为三个部分:通态损耗,断态损耗和转换过程中产生的损耗。2通态损耗On-StateLossesTheelectricalswitchesconductheavycurrentandhavenonzerovoltageacrosstheswitchintheon-state.Theon-statepowerlossesaregivenbyPon=Usonif.这个电子开关能导通大电流,并且在通态时有非零的压降。这个通态功率损耗的公式为Pon=Usonif.TheUsonandIfarerespectivelytheswitchvoltageinth
5、eon-stateandtheforwardcurrentthroughtheswitch.Forexample,thetypicalpowerdiodesandthepowertransistorshavenearly0.5tolvoltacrossthemintheon-state.Theforwardcurrentscanbehundredstothousandsofamperes.Theon-statepowerlossesareverysignificant.其中Uson是通态时开关上的压降,if是流过开关的电流。例如,典型的功率二极
6、管和功率晶体管有近似0.5~1伏的通态压降。而电流会有数百到数千安培。这个通态损耗非常重要。3断态损耗Off-StateLossesTheelectricalswitcheswithstandhighvoltagesandhavenonzeroleakagecurrentthroughtheswitchintheoff-state.Theoff-statepowerlessesaregivenbyPoh=Uoffir在关断状态时,电子开关到经受得起高电压,并会有非零的漏电流。断态损耗的公式为Poh=Uoffir.TheUsoffandIrare
7、respectivelythereversebiasvoltageintheoff-stateandthereversecurrentthroughtheswitch.Forexample,thetypicalpowerdiodesandthepowertransistorshavehighreversevoltagesinhundredstothousandsofvoltsandmicroampstomilliampsthroughthemintheoffstate.其中Uoff在断态时的反向偏置电压,ir是流过开关的反向漏电流。例如,典型的
8、功率二极管和功率晶体管有很高的反向压降几百到几千伏和几微安到几毫安的漏电流。4转换损耗Transition-StateLossesThepractic
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