多电平高压变频器的研究

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1、效开关频率与输出电压谐波关系的数学模型。对单元级联型变频器的输出谐波分布规律进行了研究，并进一步分析了其输出谐波与各影响因素之间的关系，最终论证单元级联型变频器在低频段并不是‘完美无谐波’的；其次结合功率单元的拓扑结构，研究了变频器在制动和减速过程中能量的流动，并通过仿真深入分析了各因素对制动过程中的泵升电压的影响，进而得出封锁系统脉冲可以有效的抑止制动能量的回馈；最后针对单元级联型变频器的模块化结构，结合工程应用中的问题，进一步分析了功率单元中IGBT的失效机理以及相关旁路保护措施，指出故障单元的保护动作需要在10---一2

2、0ms以内完成。多电平高压大容量变频器在有效地解决其低频输出特性、制动能量回馈以及单元监控保护等问题后，必定能更全面的体现其高效、环保、节能的特色。关键词：多电平，单元级联型变频器，输出谐波分布，制动能量，旁路保护AbstractResearchanddevelopmentofmulti-levelconverters谢tllllighvoltageandlargecapacityishelpfultoimprovethelevelofenergyutilizationandindustryautomationin0111"c

3、ountry．Fromthesettingofmulti-levelconverters，andthebasicofthemulti—cell-cascadeinverter,thispapershowsthestudiesandanalysis，includingthespectrumofoutputharmonic，theprocessofbrakeenergy,theprotectofcellbreakdown，andSOon．Firstly，basedontheprincipleofSPWMandFourier-ana

4、lysistheory，themodelsarebuiltfmally，whichCanbeusedtocalculatetherelationshipbetweentheswitchingfrequencyofmulti—cell-cascadeinverterandtheharmonicofoutputwave．Thispapergivestheanalysis，whichistheoutputharmonicspectrumdistributionofmulti·-cell--cascadeinverterandther

5、elationshipbetweentheoutputharmonicandtheinfluencefactors．ItprovesnoPERFECTHARMONYatthelowfrequencyintheend．Secondly，combining埘t}lthestructureofthepowercell，theenergyflowingoftheinverterduringtheprocessofbrakinganddeceleratingisshowedbythepaper．Accordingtothesimulat

6、ion，itstudiestheinfluencefactorsforthepumpvoltageinthebrakeprocess，andthengivestheresultthattheclosingofsystemPWMpulsescallrestrainthefeedbackofthebrakeenergy．Finally，forthemodeldesignofthemulti-cell-cascadeinverterandtheproblemsintheproject，thepaperfurtheranalyzest

7、heinvalidprincipleoflGBTandrelatedbypassprotectmethods，thenprovesthattheprotectshouldbefinishedinlessthan10or20ms．Multi—levelconverters、)l，itllhi曲voltageandlargecapacitywillall-roundlyexpressitscharacteristicofefficiency,EnergySaving，Environmentalprotection，afterres

8、olvingtheproblemsincludingtheoutputfeatureunderlowfrequency，thefeedbackofthebrakeenergy,themonitorandprotectionofpowercell，andSOon．Keyword