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毕业 论文是高校人才培养方案中不可或缺的重要组成部分，是高校英语专业的大学生毕业前必须完成的教学任务，而论文的题目确定工作则是毕业论文管理中的首要环节。下面是我带来的关于本科英语专业毕业论文题目的内容，欢迎阅读!英语专业毕业论文题目(一) 1. 浅析 广告 翻译中的 文化 顺应处理 2. 从文化角度分析中美房地产广告的差异 3. 浅析动画《加菲猫》和《加菲猫之双猫记》中的享乐主义和利己主义 4. 圣经原型解读《弗洛斯河上的磨坊》 5. 论《卡斯特桥市长》中哈代的进化向善论思想 6. 顺从的女人——分析《荒凉山庄》中埃斯特的形象 7. 从中美传统节日对比看节日的文化内涵 8. 成人的童话——《爱丽丝漫游奇境记》中象征主义的体现 9. 简析网络时代英语全球化 10. 《查泰莱夫人的情人》的生态女性主义解读 11. 从社会文化价值方面比较中美情景喜剧差异 12. 论《喧哗与骚动》中昆丁的宿命 13. 《蝇王》的启示：理性的呼唤 14. 中文旅游文本英译中的歧义现象分析 15. 从中美婚宴差异看集体主义和个人主义 16. 影响非英语专业大一新生口语输出的因素 17. 《走出非洲》：走出迪内森的矛盾态度 18. 旅游宣传资料中的误译与解决 方法 19. 从女性主义角度解读华顿《纯真年代》中的埃伦 20. 电子词典与 英语学习 英语专业毕业论文题目(二) 1. 英语习语与 ____ 2. 《伤心咖啡馆之歌》中爱米利亚性别身份分析 3. 从关联理论的角度欣赏幽默翻译 4. 英语缩略语及其语用功能 5. 英专和非英专学生 英语 作文 中错误的对比研究 6. 武汉方言对英语语音的影响及其对教学的启示 7. 中西行星命名的文化探源 8. 英语新闻中的新词 9. 中国古典诗歌英译中对“三美”理论的探索 10. 从电影《七宗罪》浅析原罪 11. 浅论体态语的社会功能 12. 中西 思维方式 差异对中英语篇的影响 13. 中国和西方国家婚俗的比较 14. 浅析合作原则的违背在广告语言中的运用 15. 浅析电影《推手》中中美家庭的文化冲突 16. 从广告语言看中美文化价值观差异 17. 用言语行为理论浅析英语广告中的双关语 18. 论新闻英语汉译中的归化与异化策略 19. 以Of Study(《论读书》)的两个中译本为例浅析译者主体性 英语专业毕业论文题目(三) 1. 广告语言模糊性的语用研究 2. 利用美剧进行 英语听力 自主学习 3. 大学生 英语口语 学习动机研究 4. 从文化视角看中国白酒广告 5. 从功能翻译看《围城》英译本中文化信息的传递 6. 对《达罗卫夫人》中克莱丽莎和塞普提默斯形象的研究 7. 公示语汉译英错误及对策探析 8. 探究美国安利公司的 企业文化 ：基于其网站内容的文本分析 9. 运用写长法促进 英语写作 能力的提高 10. 中美“面子文化”对比分析 11. 英汉恭维语和告别语的对比分析 12. 英汉爱情隐喻的对比研究 13. 新闻英语汉译的翻译技巧浅析 14. 中美家庭文化比较 15. 从文化的角度浅析中美企业 人力资源管理 的差异 16. 华中农业大学英语专业学生高级英语学习状况调查 17. 跨文化交际中中西方馈赠礼仪刍议 18. 解读《双城记》中的人道主义思想 19. 论《了不起的盖茨比》中的消费主义 20. 从戴姆勒克莱斯勒事件看文化因素对跨国企业合并的影响 21. 对中美离岸外包过程中跨文化交际案例的分析 22. 从"老友记"中看合作原则在英语称赞语及其回应语中的应用 23. 浅论美国文化与美语词汇 24. 英汉植物词语联想意义的跨文化对比 25. 一个被忽视的“准则英雄”——论《永别了，武器》中的女主人公凯瑟琳 英语专业毕业论文题目(四) 1. 美国二十世纪六十年代反战文化研究 2. 中国英语热的真相——文化帝国主义 3. 中美恭维语对比研究 4. 论民族中心主义与美国媒体近年来涉华报道 5. 从弗大枪击案看美国的枪支问题 6. 《推销员之死》中威利与比夫的父子关系 7. 从拉康的镜像理论看杨克的悲剧根源 8. 从正负值面子理论简析中美面子差异 9. 中国菜名翻译中的文化翻译策略 10. 从旧南方到新南方——斯佳丽·奥哈拉在内战前后的成长历程 11. 探究家乐福公司的企业文化:基于其网站内容的文本分析 12. 汉语对英语写作词汇的负迁移作用 13. 《美国悲剧》的消费文化分析 14. 从二语习得角度对比分析英语习语学习中的翻译导向模式与文化导向模式 15. 礼貌原则在英文商务信函中的应用 16. 南方哥特式小说特征在《心是孤独的猎手》中的体现 17. 城市公示语的汉译英探索 18. 归化与异化理论在汉语 歇后语 翻译中的应用 19. 《婚礼的成员》中弗兰淇·亚当斯双性同体现象的研究 20. 论《喜福会》中的文化冲突与共存 猜你喜欢： 1. 英语系文化类毕业论文 2. 本科英语专业毕业论文题目 3. 英语专业毕业论文选题文化 4. 翻译英语专业毕业论文选题 5. 英语语言学论文题目参考大全
英语专业毕业论文选题
1、浅析雾都孤儿的反讽性
2、海明威短篇小说中的老人形象分析
3、论英源外来词的翻译
4、从电影三个白痴看印度的社会问题
5、教师提问对学生思维发展的影响
6、浅谈英语阅读中的词汇教学方法
7、山东省英语教育培训机构现状调查
8、初中英语教学中微课的构建与应用
9、远大前程一部成长小说角度下的教育小说
10、论喜福会中中美文化的冲突及磨合
11、传播学视角下旅游文本的汉英翻译策略研究
12、角色扮演活动在小学英语课堂中的有效性研究
13、“场依存，场独立”认知风格对高中生英语阅读的影响
14、中国幼儿英语浸入式教学方法探究15、从女性主义角度研究紫色
关于英语专业的论文题目，学术堂整理了十五个好写的，供大家参考：1．《红字》中海丝特 白兰不理智的一面（The Irrational Side of Hester Prynne of The Scarlet Letter）2. 《董贝父子》中的矛盾冲突（The Conflict in Donbey and Son）3. 论文化不同对联想意义及翻译的影响（On Influence of Cultural Differences on Associative Meanings and Translation）4. 美国教育的衰弱（The Drop of American Education）5. 19世纪欧洲移民对美国工业化的积极影响（The Positive Impacts of European Immigration on American Industrialization in the 19th Century。6. 朱丽叶之人物分析（Character Studies in Juliet）7. 主述理论在文学中的运用（The Application of the Thematic Theory in Literature）8. 语用学中的会话含义理论（Conversational Implicature Theory in Pragmatics）9. 英语语音简析及对提高初学者口语的指导（A Brief Analysis of English Phonetics as well as a Guide to Improve Learners’ Oral English）10. 比较两种对于哈姆雷特复仇的评论（Comparison on Two Kinds of Comments on Hamlet’s Revenge）11. 英语语言中的性别歧视 (Sexism in English Language)12. 英语的学与教 (English Learning and Teaching)13. 由美国2004年总统选举所想到的 (More than 2004 Presidential Election)14. 论腐朽世界中的纯洁品质——关于《雾都孤儿》的赏析 (The Purity in a Corrupt World—An Analysis of Oliver Twister)15. 论理智与情感之关系——对《理智与情感》的人物分析
1、针对你研究的某一个范围具体命题。如：中学教育，小学教育，职业教育等等。2、侧重某一个教学法进行论述和研讨。如：行动导向教学法。3、侧重对学生德育教育、思想教育开展论文研究。4、对某一领域的教学调研和调查。
题目不要太大，也不要太小，太大了面太广容易泛泛，小了就无材料可查，没东西可写。写你熟悉的 资料好查的 参考
提供一些英语专业的毕业论文题目，供参考。
额 我也是商务英语专业的 貌似电脑里还有那时候的选题 差不多600多个你留个邮箱 我下班回去发给你吧 ===============================已发送 请查收
学术堂精心整理了五十个新颖并好写的商务英语专业毕业论文题目，供大家参考：1、商务英语的特点及翻译技巧2、商务英语函电翻译技巧3、商务英语信函的语体分析4、浅谈商务信函的文体特征5、商务英语学习方法探究6、商务英语学习中跨文化交际能力的培养7、国际商务谈判中应注意的文化因素8、商务谈判中的跨文化冲突9、试论普通英语与商务英语的差异10、商务谈判中的语言艺术11、商标名称的翻译与策略12、广告英语的分类与分析13、试论文化因素对商务活动的作用14、商务英语听力策略研究15、商务英语写作问题研究16、商务英语考试技巧研究17、电子商务对国际贸易的影响及对策18、国际商务英语信函话语分析19、商务英语发展现状浅祈20、商务英语翻译技巧21、商务英语函电中的文化因素初探22、商务英语专业人才培养模式改革与实践23、试论文化导入在商务英语教学中的作用24、中英文广告标题的共同点25、中英文广告传播之语言特色及跨文化问题26、商品译文的品牌形象对商务英语翻译教学的启示27、商务英语翻译标准初探28、试论商务英语写作的简洁礼貌原则及写作技巧29、我国在国际贸易中实施反倾销的应对策略30、商务函电翻译的用词技巧31、商标名称的翻译与策略32、商务谈判中的语言艺术33、商务谈判的文化障碍34、商务英语课程设置的探讨35、商务谈判中英语的重要性36、商务英语学习中跨文化交际能力的培养37、商务谈判中的跨文化冲突38、商务英语写作中的错误与商务英语写作教学之间的关系39、英语口语或语法在商务领域中的运用40、浅谈英语告示语的语言特色与翻译41、商务英语专业毕业生就业岗位探讨42、浅谈高职学生英语听说技能的培养43、文化差异对商务汉英翻译的影响44、商务英语函电在对外贸易中的作用45、浅谈商务英语写作时避免修饰语错位的方法46、制单工作在国际结算中的地位47、国际商务单证的作用和种类48、浅析海运提单的风险及防范措施49、如何翻译好日常商务文书50、跨文化商务交际中的语言和非语言因素
找论文去万方论文库，那里有很多方面的论文。如果你自己去下载不不了，推荐去淘宝的[翰林书店]店铺，能及时帮你下载论文的
学术堂整理了十五个好写的商务英语专业论文题目,供大家参考:1、关于中国职业高等院校商务英语课程设计中一些重要问题的思考2、研究性学习在中职商务英语口语教学中的应用3、商务合同语篇中的语法隐喻研究4、英语广告在商务英语教学中的个案应用5、教师反馈对提高商务英语写作准确性作用的研究6、论任务型教学法在商务英语写作教学中的运用7、建构主义指导下的商务英语课程设计研究8、高职生商务英语词汇学习策略实证研究9、商务英语新词构词研究10、剑桥商务英语口语考试的构念效度分析11、独立学院商务英语专业课程设置初探12、任务导向的高职商务课程开发研究13、商务英语笔译试题设计研究14、商务英语写作能力量表研究15、词组方法在商务英语词汇学习中的有效性研究
关于英语专业的论文题目，学术堂整理了十五个好写的，供大家参考：1．《红字》中海丝特 白兰不理智的一面（The Irrational Side of Hester Prynne of The Scarlet Letter）2. 《董贝父子》中的矛盾冲突（The Conflict in Donbey and Son）3. 论文化不同对联想意义及翻译的影响（On Influence of Cultural Differences on Associative Meanings and Translation）4. 美国教育的衰弱（The Drop of American Education）5. 19世纪欧洲移民对美国工业化的积极影响（The Positive Impacts of European Immigration on American Industrialization in the 19th Century。6. 朱丽叶之人物分析（Character Studies in Juliet）7. 主述理论在文学中的运用（The Application of the Thematic Theory in Literature）8. 语用学中的会话含义理论（Conversational Implicature Theory in Pragmatics）9. 英语语音简析及对提高初学者口语的指导（A Brief Analysis of English Phonetics as well as a Guide to Improve Learners’ Oral English）10. 比较两种对于哈姆雷特复仇的评论（Comparison on Two Kinds of Comments on Hamlet’s Revenge）11. 英语语言中的性别歧视 (Sexism in English Language)12. 英语的学与教 (English Learning and Teaching)13. 由美国2004年总统选举所想到的 (More than 2004 Presidential Election)14. 论腐朽世界中的纯洁品质——关于《雾都孤儿》的赏析 (The Purity in a Corrupt World—An Analysis of Oliver Twister)15. 论理智与情感之关系——对《理智与情感》的人物分析
题目不要太大，也不要太小，太大了面太广容易泛泛，小了就无材料可查，没东西可写。写你熟悉的 资料好查的 参考
1、针对你研究的某一个范围具体命题。如：中学教育，小学教育，职业教育等等。2、侧重某一个教学法进行论述和研讨。如：行动导向教学法。3、侧重对学生德育教育、思想教育开展论文研究。4、对某一领域的教学调研和调查。
语言测试在英语学习中的重要性 比较中西课堂教学及其对学生能力培养的影响 游戏在儿童英语教学中的运用 小学英语情趣教学漫谈 论中学英语教学中跨文化意识的培养 课堂气氛对高中英语教学效果的影响 记忆在语篇理解过程中的作用 记忆在词汇习得中的作用 谈英语阅读的制约因素及对策 跨文化交际中的体态语和中学英语教学 分析具有中国特色的双语教学 非智力因素在大学生英语学习中的影响 英语教学中的情感因素 论外语自主学习中师生的角色 让我们的思绪飞扬---浅谈在英语课堂教学中影响学生发言主动性的因素 C2C贸易中的写作技巧 大学生英语写作问题研究 文化词及其在外语教学中的功能 英语学习策略的成功案例 文化差异对阅读理解的影响 浅谈多媒体辅助英语教学及教师角色的改变 论母语文化在英语教学中的地位 英语教学中的文化导入
用于分布式在线UPS中的并联逆变器的一种无线控制器A Wireless Controller for Parallel Inverters in Distributed Online UPS SystemsJosep M. Guerrero', Luis Garcia de Vicufia", Jose Matas'*, Jaume Miret", and Miguel Castilla". Departament #Enginyeria de Sistemes, Automatica i Informhtica Industrial. Universitat Polithica de CatalunyaC. Comte d'Urgell, 187.08036 -Barcelona. Spain. Email: .. Departament #Enginyeria Electrbnica. Universitat Polit6cnica de CatalunyaAV. Victor BaLguer s/n. 08800I - Vilanova i la Geltrh. SpainAbsiract - In this paper, a novel controller for parallelconnectedonline-UPS inverters without control wireinterconnections is presented. The wireless control technique isbased on the well-known droop method, which consists inintroducing P-oand Q-V schemes into the inverters, in order toshare properly the power drawn to the loads. The droop methodhas been widely used in applications of load sharing betweendifferent parallel-connected inverters. However, this methodhas several drawbacks that limited its application, such as atrade-off between output-voltage regulation and power sharingaccuracy, slow transient response, and frequency and phasedeviation. This last disadvantage makes impracticable themethod in online-UPS systems, since in this case every modulemust be in phase with the utility ac mains. To overcome theselimitations, we propose a novel control scheme, endowing to theparalleled-UPS system a proper transient response, strictlyfrequency and phase synchronization with the ac mains, andexcellent power sharing. Simulation and experimental resultsare reported confirming the validity of the proposed approach.1. INTRODUCTIONThe parallel operation of distributed Uninterruptible PowerSupplies (UPS) is presented as a suitable solution to supplycritical and sensitive loads, when high reliability and poweravailability are required. In the last years, many controlschemes for parallel-connected inverters has been raised,which are derived from parallel-schemes of dc-dc converters[I], such as the master-slave control [2], or the democraticcontrol [3]. In contrast, novel control schemes have beenappeared recently, such as the chain-structure control [4], orthe distributed control [ 5 ] . However, all these schemes needcontrol interconnections between modules and, hence, thereliability of the system is reduced since they can be a sourceof noise and failures. Moreover, these communication wireslimited the physical situation ofthe modules [6].In this sense, several control techniques has been proposedwithout control interconnections, such as the droop method.In this method, the control loop achieves good power sharingmaking tight adjustments over the output voltage frequencyand amplitude of the inverter, with the objective tocompensate the active and reactive power unbalances [7].This concept is derived from the power system theory, inwhich the frequency of a generator drops when the powerdrawn to the utility line increases [8].0-7803-7906-3/03/$17.00 02003 IEEE. 1637However, this control approach has an inherent trade-offbetween voltage regulation and power sharing. In addition,this method exhibits slow dynamic-response, since it requireslow-pass filters to calculate the average value of the activeand reactive power. Hence, the stability and the dynamics ofthe whole system are hardly influenced by the characteristicsof these filters and by the value of the droop coefficients,which are bounded by the maximum allowed deviations ofthe output voltage amplitude and frequency.Besides, when active power increases, the droopcharacteristic causes a frequency deviation from the nominalvalue and, consequently, it results in a variable phasedifference between the mains and the inverter output voltage.This fact can be a problem when the bypass switch mustconnect the utility line directly to the critical bus in stead ofits phase difference. In [9], two possibilities are presented inorder to achieve phase synchronization for parallel lineinteractiveUPS systems. The first one is to locate a particularmodule near the bypass switch, which must to synchronizethe output voltage to the mains while supporting overloadcondition before switch on. The second possibility is to waitfor the instant when phase matching is produced to connectthe bypass.However, the mentioned two folds cannot be applied to aparallel online-UPS system, since maximum transfer timeought to be less than a % of line period, and all the modulesmust be always synchronized with the mains when it ispresent. Hence, the modules should be prepared to transferdirectly the energy from the mains to the critical bus in caseof overload or failure [lo].In our previous works [11][12], we proposed differentcontrol schemes to overcome several limitations of theconventional droop method. However, these controllers bythemselves are inappropriate to apply to a parallel online-UPS system. In this paper, a novel wireless control scheme isproposed to parallel different online UPS modules with highperformance and restricted requirements. The controllerprovides: 1) proper transient response; 2) power sharingaccuracy; 3) stable frequency operation; and 4) good phasematching between the output-voltage and the utility line.Thus, this new approach is especially suitable for paralleled-UPS systems with true redundancy, high reliability andpower availability. Simulation and experimental results arereported, confirming the validity of this control scheme.Fig. 1. Equivalenl cimuif ofan invener connecled 10 a bust"Fig. 2. P-odraop function.11. REVlEW OF THE CONVENTIONAL DROOP METHODFig. 1 shows the equivalent circuit of an inverter connectedto a common bus through coupled impedance. When thisimpedance is inductive, the active and reactive powers drawnto the load can be expressed asEVcosQ - V2 Q=where Xis the output reactance of an inverter; Q is the phaseangle between the output voltage of the inverter and thevoltage of the common bus; E and V are the amplitude of theoutput voltage of the inverter and the bus voltage,respectively.From the above equations it can be derived that the activepower P is predominately dependent on the power angle Q,while the reactive power Q mostly depends on the outputvoltageamplitude. Consequently, most of wireless-control ofparalleled-inverters uses the conventional droop method,which introduces the following droops in the amplitude Eand the frequency U of the inverter output voltageu = w -mP (3)E = E ' - n Q , (4)being W* and E' the output voltage frequency and amplitudeat no load, respectively; m and n are the droop coefficientsfor the frequency and amplitude, respectively.Furthermore, a coupled inductance is needed between theinverter output and the critical bus that fixes the outputimpedance, in order to ensure a proper power flow. However,it is bulky and increase:; the size and the cost of the UPSmodules. In addition, tho output voltage is highly distortedwhen supplying nonlinezr loads since the output impedanceis a pure inductance.It is well known that if droop coefficients are increased,then good power sharing is achieved at the expense ofdegrading the voltage regulation (see Fig. 2).The inherent trade-off of this scheme restricts thementioned coefficients, which can be a serious limitation interms of transient response, power sharing accuracy, andsystem stability.On the other hand, lo carry out the droop functions,expressed by (3) and (4), it is necessary to calculate theaverage value over one line-cycle of the output active andreactive instantaneous power. This can be implemented bymeans of low pass filters with a smaller bandwidth than thatof the closed-loop inverter. Consequently, the powercalculation filters and droop coefficients determine, to a largeextent, the dynamics and the stability of the paralleledinvertersystem [ 131.In conclusion, the droop method has several intrinsicproblems to be applied 1.0 a wireless paralleled-system ofonline UPS, which can he summed-up as follows:Static trade-off between the output-voltage regulation(frequency and amplitude) and the power-sharingaccuracy (active an4d reactive).2) Limited transient response. The system dynamicsdepends on the power-calculation filter characteristics,the droop coefficients, and the output impedances.Lost of ac mains synchronization. The frequency andphase deviations, due to the frequency droop, makeimpracticable this method to a parallel-connectedonline UPS system, in which every UPS should becontinuously synchronized to the public ac supply.1)3)111. PROPOSED CONTROL FOR PARALLEL ONLINE UPSINVERTERSIn this work, we will try to overcome the above limitationsand to synthesize a novel control strategy withoutcommunication wires that could be appropriate to highperformanceparalleled industrial UPS. The objective is toconnect online UPS inverters in parallel without usingcontrol interconnections. This kind of systems, also namedinverter-preferred, should be continuously synchronized tothe utility line. When an overload or an inverter failureoccurs, a static bypass switch may connect the input line tothe load, bypassing the inve:rter [14][15].Fig. 3 shows the general diagram of a distributed onlineUPS system. This system consists of two buses: the utilitybus, which is connected lo the public ac mains; and thesecure bus, connected to the distributed critical loads. Theinterface between these buses is based on a number of onlineUPS modules connected in parallel, which providescontinuously power to the: loads [16]. The UPS modulesinclude a rectifier, a set of batteries, an inverter, and a staticbypass switch.11638Q ac mainsutility busI I Ij distributed loads !Fig. 3. Online distributed UPS system.syposr /I 4(4Fig. 4. Operation modes of an online UPS.(a) Normal operation. (b) Bypass operation. (c) Mains failureThe main operation modes of a distributed online UPS1) Normal operation: The power flows to the load, fromthe utility through the distributed UPS units.2) Mains failure: When the public ac mains fails, theUPS inverters supply the power to the loads, from thebatteries, without disruption.Bypass operation: When an overload situation occurs,the bypass switch must connect the critical busdirectly to the ac mains, in order to guarantee thecontinuous supply of the loads, avoiding the damageof the UPS modules.For this reason, the output-voltage waveform should besynchronized to the mains, when this last is present.system are listed below (see Fig. 5):3)Nevertheless, as we state before, the conventional droopmethod can not satisfy the need for synchronization with theutility, due to the frequency variation of the inverters, whichprovokes a phase deviation.To obtain the required performance, we present a transientP-w droop without frequency-deviation in steady-state,proposed previously by OUT in [ 111w=o -mP (5)where is the active power signal without the dccomponent,which is done by. -I t -1sP= p ,( s + t - ' ) ( s + o , )being zthe time constant of the transient droop action.The transient droop function ensures a stable frequencyregulation under steady-state conditions, and 'at the sametime, achieves active power balance by adjusting thefrequency of the modules during a load transient. Besides, toadjust the phase of the modules we propose an additionalsynchronizing loop, yieldingo=w'-m%k,A$, (7)where A$ is the phase difference between the inverter and themains; and k, is the proportional constant of the frequencyadjust. The steady-state frequency reference w* can beobtained by measuring the utility line frequency.The second term of the previous equality trends to zero insteady state, leading tow = w' - k4($ -@'), (8)being $and $* the phase angles of the output voltage inverterand the utility mains, respectively.Taking into account that w = d $ / d t , we can obtain thenext differential equation, which is stable fork, positived$ *dt dt- + km$ = - + k,$' . (9)Thus, when phase difference increases, frequency willdecrease slightly and, hence, all :he UPS modules will besynchronized with the utility, while sharing the power drawnto the loads.IV. CONTROLLIEMRP LEMENTATIONFig. 5 depicts the block diagram of the proposedcontroller. The average active power P , without the dccomponent, can be obtained by means of multiplying theoutput voltage by the output current, and filtering the product........................................................................................io",.LSj'nchronirorion loop.......................................................................................Fig. 5. Block diagram of the proposed controller.using a band-pass filter. In a similar way, the averagereactive power is obtained, hut in this case the output-voltagemust be delayed 90 degrees, and using a low-pass filter.In order to adjust the output voltage frequency, equation(7) is implemented, which corresponds to the frequencymains drooped by two transient-terms: the transient activepower signal term; and the phase difference term, whichis added in order to synchronize the output voltage with theac mains, in a phase-locked loop (PLL) fashion. The outputvoltageamplitude is regulated by using the conventionaldroop method (4).Finally, the physical coupled inductance can be avoided byusing a virtual inductor [17]. This concept consists inemulated an inductance behavior, by drooping the outputvoltage proportionally to the time derivative of the outputcurrent. However, when supplying nonlinear loads, the highordercurrent-harmonics can increase too much the outputvoltageTHD. This can be easily solved by using a high-passfilter instead of a pure-derivative term of the output current,which is useful to share linear and nonlinear loads [I 1][12].Furthermore, the proper design of this output inductance canreduce, to a large extent, the unbalance line-impedanceimpact over the power sharing accuracy.v. SIMULATION AND EXPERIMENTARELS ULTSThe proposed control scheme, (4) and (7), was simulatedwith the parameters listed in Table 1 and the scheme shownin Fig. 6, for a two paralleled inverters system. Thecoefficients m, n, T, and kv were chosen to ensure stability,proper transient response and good phase matching. Fig. 7shows the waveforms of the frequency, circulating currents,phase difference between the modules and the utility line,and the evolution of the active and reactive powers. Note theexcellent synchronization between the modules and theACmiiinr 4 j. ...L...I.P...S...1... ..........................B...u...n...r.r..r..e..s... ................................... iFig. 6. Parallel operation oftwa online UPS modules,mains, and, at the same time, the good power sharingobtained. This characteristik let us to apply the controller tothe online UPS paralleled systems.Two I-kVA UPS modules were built and tested in order toshow the validity of the proposed approach. Each UPSinverter consisted of a single-phase IGBT full-bridge with aswitching frequency of 20 kHz and an LC output filter, withthe following parameters: 1. = 1 mH, C = 20 WF, Vi" = 400V,v, = 220 V, I50 Hz. The controllers of these inverters werebased on three loops: an inner current-loop, an outer PIcontroller that ensures voltage regulation, and the loadsharingcontroller, based on (4) and (7). The last controllerwas implemented by means of a TMS320LF2407A, fixedpoint40 MHz digital sigrial processor (DSP) from TexasInstruments (see Fig. 8), using the parameters listed in TableI. The DSP-controller also includes a PLL block in order tosynchronize the inverter with the common bus. When thisoccurs, the static bypass switch is tumed on, and the droopbasedcontrol is initiated.1640big 7 Wa\cfc)rms for twu.invencr, ;mnectcd in parallel. rpchrontred io Ihc ac mdnl.(a) Frequencics ufhoth UPS (b) Clrculattng currcni among modulcs. (CJ Phmc d!Nercn;: betucen ihc UPS a#>dth e ai mum(d) Ikiril uf the phze diNmncc (e) md (0 Activc and rcactlw pouerr "I ooih UPSNote that the iimc-acs arc deliheratcly JiNercni due in thc disiinct timuion*uni) ofthe \ inrblrr1641TABLEI.PARAMETEROSF THE PARALLELESDYS TEM.Filter Order I IFilter Cut-off Frequency I 0, I 10 I ragsFig. 8 shows the output-current transient response of theUPS inverters. First, the two UPS are operating in parallelwithout load. Notice that a small reactive current is circlingbetween the modules, due to the measurement mismatches.Then, a nonlinear load, with a crest factor of 3, is connectedsuddenly. This result shows the good dynamics and loadsharingof the paralleled system when sharing a nonlinearload.Fig. 8. Output current for the two paralleled UPS, during the connection of Bcommon nonlinear load with a crest factor of 3. (Axis-x: 20 mddiv. Axis-y:5 Mdiv.).VI. CONCLUSIONSIn this paper, a novel load-sharing controller for parallelconnectedonline UPS systems, was proposed. The controlleris based on the droop method, which avoids the use ofcontrol interconnections. In a sharp contrast with theconventional droop method, the controller presented is ableto keep the output-voltage frequency and phase strictlysynchronized with the utility ac mains, while maintaininggood load sharing for linear and nonlinear loads. This fact letus to extend the droop method to paralleled online UPS.On the other hand, the proposed controller emulates aspecial kind of impedance, avoiding the use of a physicalcoupled inductance. Th.e results reported here show theeffectiveness of the proposed approach.
不会写论文还这么嚣张?不就是250分吗得到了又怎么地？能吃呀？
Welding Automation Research in the engineering school is largely focused on problems involving sensing, modeling, and control of welding processes, i.e., welding automation. Faculty and students from electrical engineering, mechanical engineering, and material science are involved in the welding automation research. The overall objective of this research is to provide both greater productivity and enhanced quality for welding in the manufacturing environment.http://eecs.vanderbilt.edu/researchgroups/weldingautomation
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