文档名：环氧树脂高频松弛的交流电导与双极性方波击穿特性
摘要：高频非正弦电压下环氧树脂击穿表现出较强的频率依赖性,并且存在复杂的宽频电-热耦合特性.高频电压下环氧树脂交流电导,特别是载流子非线性输运过程是理解高频绝缘击穿的关键.该文以两种电工环氧树脂为研究对象,采用宽频介电谱研究环氧试样交流电导的频率与温度依赖关系,通过Almond-West模型分析得到低频下交流类直流电导率与温度的关系,低频电导随温度变化更符合Vogel-Fulcher-Tammann模型.基于Havriliak-Negami复合介质多分散松弛极化理论,分析高频、高温下的松弛行为,认为高频交流电导率主要由松弛过程α产生的极化损耗引起.通过高频双极性方波击穿测试平台,测试了重复频率双极性方波电压(500Hz,1kHz,2kHz,3kHz)下环氧试样的击穿场强,基于三参数Weibull分布统计分析特征击穿场强随频率的关系,发现击穿场强与频率呈负相关.研究提出考虑Poole-Frenkel效应的高频高场交流电导模型,并建立高频自由体积随频率变化的击穿模型.研究指出高频下分子链段振动效应增强,导致交流电导增强;高频下分子链运动滞后于频率响应,导致总体自由体积增大,造成高频击穿场强下降.研究结果对高频绝缘破坏与可靠性研究具有重要意义.
Abstract：Asoneofthesolidinsulationmaterialsofhigh-frequencytransformers(HFT),epoxyresinpresentsgoodperformanceunderhigh-frequencynon-sinusoidalelectricalvoltage.Itsinsulationperformancedependsstronglyonvoltagefrequency.Duetothelocaltemperatureriseinhigh-frequencytransformers,theelectrothermaleffectcanincreasetheconductivityofepoxyresin.Nevertheless,theACconductivityfromthedielectricspectrummeasurementcannotbeequivalenttotheACconductivitycharacteristicsunderhigh-frequencynon-sinusoidalvoltage.Therefore,thispaperstudiestheACconductivitycharacteristicsunderhigh-frequencysquarevoltagebytheFourierdecomposition.ThemechanismunderlyingtheACconductivityofepoxyresinonthebreakdownathighfrequencyisdiscussedbyimprovingthefreevolumebreakdowntheory.TherelationshipbetweentheACconductivityandthehigh-frequencybreakdownofepoxyresinisanalyzedbythehigh-frequencyrelaxationcharacteristicsandhigh-frequencyhigh-fieldconductiontheory.TwokindsofepoxyresinsamplesE1andE2werepreparedusingthesameprocessandmethod.AccordingtotheresultsofglasstransitiontemperatureTgandACconductivity,theAlmond-West(A-W)modelandHavriliak-Negami(H-N)multi-dispersionrelaxationpolarizationmodelwereusedtofitandanalyzetheACconductivityspectrumatdifferenttemperatures,andtheDCconductivityofepoxyresinatdifferenttemperatureswasalsoobtained.Then,thetemperatureandfrequencydependenceofrelaxationprocessesαandδareanalyzedaccordingtothefittingresultsoftheH-Nmodel.Accordingtotheinsulationbreakdownmeasurementresults,thebreakdowncharacteristicsoftwoepoxysampleswithin500～3000Hzwereanalyzed.Basedonthestatisticalresultsofthethree-parameterWeibulldistribution,therelationshipbetweenthefeaturedbreakdownfieldstrengthandthefrequencywasobtained.AccordingtoJonscher'suniversaldielectricresponsemodel,thePoole-Frenkeleffect,DCconductivity,andthefrequencyandelectricfieldeffectsonACconductivityunderbipolarsquarewavevoltageareanalyzed.ThefreevolumebreakdownmodelisproposedtoanalyzetheinfluenceoffrequencyontheACconductivityandhigh-frequencybreakdownintheepoxyresinsamples.AccordingtothefittingresultsoftheA-WmodelandtheH-Nmodel,theACconductivityismainlydeterminedbythepolarizationlosscausedbytherelaxationprocessαaboveTg.Therelaxationprocessαdependsonthedipoleturningpolarization,andthedipoleconcentrationintheepoxyresinsamplewithahighepoxyvalueishigh.TherelaxationprocessδisdeterminedbytheDCconductivityprocess,andδprocessisrelatedtothecarriermigrationacrossthebarrier.Thebreakdownstrengthsoftwoepoxyresinsamplesdecreasewiththeincreaseinfrequency.ThebreakdownstrengthofE1sampleisgreaterthanthatofE2.Theconclusionsareasfollowsaccordingtothemeasuredresults,fittingresults,andmodelanalysis.(1)TheACconductivityathighfrequencyandhighfieldincludesdipoleconductivityatlowfield,Poole-Frenkelemissionofchargecarriersunderhigh-frequencyelectricfield,andDCconductivity.TheACconductivityincreaseswiththeincreaseinfrequencyorelectricfield.(2)Thehysteresiseffectofmovementsofmolecularchainsegmentsunderthehigh-frequencyelectricfieldsbecomesobviousasthefrequencyincreases.Themaximumlengthoftheunoccupiedequivalentfreevolumebetweenthemolecularchainsincreases,reducingbreakdownstrengthathigh-frequencyvoltage.Inaddition,themoleculargroupspacingdecreaseswiththeincreaseinfrequency,leadingtothedecreaseofcarrierhoppingpotentialbarrierandtheincreaseinACconductivityofepoxyresinsamples.
作者：蒋起航 王威望 钟禹 李盛涛 徐永生 Author：JiangQihang WangWeiwang ZhongYu LiShengtao XuYongsheng
作者单位：电力设备电气绝缘国家重点实验室(西安交通大学)西安710049南方电网科学研究院有限责任公司直流输电技术国家重点实验室广州510080
刊名：电工技术学报
Journal：TransactionsofChinaElectrotechnicalSociety
年，卷(期)：2024, 39(4)
分类号：TM215.1
关键词：环氧树脂 交流电导 双极性方波电压 自由体积 高频击穿
Keywords：Epoxyresin ACconductivity bipolarsquarewavevoltage freevolume highfrequencybreakdown
机标分类号：TN873+.93TN386.1TM214
在线出版日期：2024年3月5日
基金项目：国家自然科学基金，陕西省自然科学基础研究计划青年项目，电力设备电气绝缘国家重点实验室中青年基础研究创新基金项目环氧树脂高频松弛的交流电导与双极性方波击穿特性[
期刊论文] 电工技术学报--2024, 39(4)蒋起航 王威望 钟禹 李盛涛 徐永生高频非正弦电压下环氧树脂击穿表现出较强的频率依赖性,并且存在复杂的宽频电-热耦合特性.高频电压下环氧树脂交流电导,特别是载流子非线性输运过程是理解高频绝缘击穿的关键.该文以两种电工环氧树脂为研究对象,采用宽频...参考文献和引证文献
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环氧树脂高频松弛的交流电导与双极性方波击穿特性 AC Conductivity with High Frequency Relaxation and Breakdown Characteristics of Epoxy Resin under Bipolar Square Wave Voltage
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