外文翻譯-太陽(yáng)跟蹤系統(tǒng)

畢業(yè)設(shè)計(jì)（論文）譯文及原稿譯文題目雙軸太陽(yáng)跟蹤器的設(shè)計(jì)與實(shí)現(xiàn)光學(xué)傳感器基于單電機(jī)的光伏系統(tǒng)原稿題目DesignandImplementationofaSunTrackerwithaDual-AxisSingleMotorforanOpticalSensor-BasedPhotovoltaicSystem原稿出處DepartmentofElectricalEngineering原稿出處雙軸太陽(yáng)跟蹤器的設(shè)計(jì)與實(shí)現(xiàn)光學(xué)傳感器

基于單電機(jī)的光伏系統(tǒng)摘要：能源耗竭和全球氣候變暖是地方發(fā)展的雙重威脅，解決方法的公共利益中心是利用可再生的能源資源。太陽(yáng)能源是一種最有前途的可再生能源。太陽(yáng)跟蹤器可以大幅度提高電力生產(chǎn)。本文提出了一種新穎的利用的雙軸太陽(yáng)跟蹤光伏系統(tǒng)的設(shè)計(jì)反饋控制理論以及四象限光電阻（LDR）傳感器和簡(jiǎn)單的電子電路提供強(qiáng)健的系統(tǒng)性能。擬議的系統(tǒng)采用獨(dú)特的雙軸交流電機(jī)和一個(gè)獨(dú)立的光伏逆變器完成太陽(yáng)能跟蹤?？刂茍?zhí)行是一種簡(jiǎn)單而有效的技術(shù)創(chuàng)新設(shè)計(jì)。此外構(gòu)造了一個(gè)按比例縮小的實(shí)驗(yàn)室原型來(lái)驗(yàn)證該計(jì)劃的可行性。實(shí)驗(yàn)證實(shí)了太陽(yáng)跟蹤器的有效性。最后，本研究結(jié)果可以作為未來(lái)太陽(yáng)能應(yīng)用的參考。關(guān)鍵詞：雙軸太陽(yáng)跟蹤器；太陽(yáng)能光伏板；反饋控制理論的光依賴電阻器；獨(dú)立光伏逆變器；能量增益1、介紹隨著人口和經(jīng)濟(jì)的發(fā)展，能源危機(jī)的問(wèn)題的快速增加和全球變暖影響今天是一個(gè)令人日益感到關(guān)切?？稍偕茉促Y源的利用是解決這些問(wèn)題的關(guān)鍵。太陽(yáng)能是的主要來(lái)源之一清潔、豐富和取之不盡，用之不竭的能源，這不僅提供了可替代能源資源，但也提高了環(huán)境污染。最直接的和技術(shù)上有吸引力地利用太陽(yáng)能是通過(guò)光伏轉(zhuǎn)換。（也稱為太陽(yáng)能電池）在PV電池的物理是非常類似于經(jīng)典的p—n結(jié)型二極管。光伏電池將陽(yáng)光直接轉(zhuǎn)化為直流電（DC）電力由光伏效應(yīng)[1，2]。光伏面板或模塊是光伏電池封裝互連的大會(huì)。在為了最大限度地從太陽(yáng)能電池板，一個(gè)需要保留小組在最佳的輸出功率位置垂直于白天的太陽(yáng)輻射。因此，就必須有它的裝備與太陽(yáng)跟蹤器。相對(duì)于固定效應(yīng)的面板，由太陽(yáng)跟蹤器驅(qū)動(dòng)手機(jī)光伏面板可能刺激一貫的能量增益的光伏面板。太陽(yáng)能跟蹤是最合適的技術(shù)，以提高電力生產(chǎn)的光伏系統(tǒng)。要實(shí)現(xiàn)較高程度的跟蹤精度，幾種方法已廣泛進(jìn)行了研究。一般來(lái)說(shuō)，可以列為要么基于太陽(yáng)能的開環(huán)跟蹤類型運(yùn)動(dòng)數(shù)學(xué)模型或使用傳感器基于反饋的閉環(huán)跟蹤類型控制器[3——5]。在開環(huán)跟蹤方法，跟蹤公式或控制算法。談到文學(xué)[6-10]，方位角和俯仰角，太陽(yáng)角測(cè)定太陽(yáng)運(yùn)動(dòng)的軌跡模型或在給定的日期、時(shí)間和地理信息的算法。的控制算法在微處理器控制器[11，12]被處死。在閉環(huán)跟蹤各種活動(dòng)傳感器設(shè)備，例如電荷耦合器件（Ccd）[13-15]或光的方法依賴電阻器（異地）[12,16-19]被用于感受太陽(yáng)的位置及反饋錯(cuò)誤信號(hào)然后生成控制系統(tǒng)要不斷收到的最大的太陽(yáng)能輻射在光伏面板。本文提出了在這個(gè)問(wèn)題上的實(shí)證研究方法。太陽(yáng)能跟蹤方法可以通過(guò)使用單軸式方案[12,19-21]，和雙軸結(jié)構(gòu)的高精度系統(tǒng)[16——18,22——27]。一般來(lái)說(shuō)，與單軸跟蹤系統(tǒng)單自由度跟隨太陽(yáng)的運(yùn)動(dòng)從東到西白天時(shí)雙軸跟蹤也跟隨太陽(yáng)的仰角。近年來(lái)，已越來(lái)越多研究關(guān)注的雙軸太陽(yáng)跟蹤系統(tǒng)的容量。然而，在現(xiàn)有的研究中，其中絕大多數(shù)用兩個(gè)步進(jìn)電機(jī)[22,23]或[16,17,24,25]兩個(gè)直流電動(dòng)機(jī)來(lái)執(zhí)行雙軸太陽(yáng)能跟蹤。有兩個(gè)跟蹤電機(jī)的設(shè)計(jì)，兩個(gè)電機(jī)裝在垂直軸上，甚至在某些方向?qū)R它們。在某些情況下，兩臺(tái)發(fā)動(dòng)機(jī)都在同一時(shí)間[5]不能動(dòng)彈了。此外，這類系統(tǒng)總是涉及使用微處理器芯片作為控制平臺(tái)的復(fù)雜跟蹤策略。在這項(xiàng)工作，只有單一的跟蹤電動(dòng)機(jī)，采用雙軸企圖取得了制定和實(shí)施一種簡(jiǎn)單而有效的控制方案。兩軸間的陽(yáng)光跟蹤被允許在他們各自的范圍內(nèi)同時(shí)移動(dòng)。利用常規(guī)電子線路，需要沒(méi)有編程或計(jì)算機(jī)的接口。此外，擬議的制度使用獨(dú)立的光伏逆變器驅(qū)動(dòng)電機(jī)，并提供電源。該系統(tǒng)是獨(dú)立和自主。實(shí)驗(yàn)結(jié)果證明跟蹤的可行性光伏發(fā)電系統(tǒng)并驗(yàn)證了提出的控制實(shí)現(xiàn)的優(yōu)點(diǎn)。2、開發(fā)閉環(huán)太陽(yáng)能跟蹤系統(tǒng)發(fā)達(dá)國(guó)家的閉環(huán)太陽(yáng)能跟蹤系統(tǒng)的框圖如圖1所示描述組成和系統(tǒng)的互連。閉環(huán)跟蹤的方法，太陽(yáng)能跟蹤問(wèn)題是如何使光伏面板位置（輸出），跟隨陽(yáng)光（輸入）盡可能地接近的位置。基于傳感器的反饋控制器包含LDR傳感器、差分放大器和比較器。在跟蹤操作中，低劑量輻射傳感器測(cè)量陽(yáng)光作為參考輸入信號(hào)的強(qiáng)度。低劑量輻射傳感器所產(chǎn)生的電壓不平衡被放大，然后生成反饋誤差電壓。誤差電壓成正比陽(yáng)光位置與光伏面板位置之間的差異。在這時(shí)間的比較將與指定的閾值（公差）誤差電壓進(jìn)行比較。如果比較器輸出變?yōu)楦唠娖綘顟B(tài)、電機(jī)驅(qū)動(dòng)和繼電器被激活，旋轉(zhuǎn)雙軸（方位角和俯仰角）跟蹤電機(jī)和光伏面板給孫因此，反饋控制器執(zhí)行的臉重要功能：光伏面板和陽(yáng)光不斷地進(jìn)行監(jiān)測(cè)并發(fā)送微分控制信號(hào)來(lái)驅(qū)動(dòng)光伏面板，直到誤差電壓小于預(yù)先指定的閾值。圖1.太陽(yáng)能跟蹤系統(tǒng)框圖。系統(tǒng)會(huì)跟蹤太陽(yáng)高度自主的方位角和俯仰角角。整個(gè)工作圖2和圖3所示的流程圖中，總結(jié)了算法。四個(gè)陽(yáng)光的強(qiáng)度LDR基于傳感電路測(cè)量不同的方向。電壓vE、大眾、vS和vN是定義為傳感電壓產(chǎn)生的東、西、南、北異地分別。在嘗試從光伏面板、方位角和仰角跟蹤過(guò)程可以得出最大功率同時(shí)繼續(xù)進(jìn)行直到光伏面板垂直對(duì)齊在陽(yáng)光下。追蹤器安裝并不局限于地理位置。圖2.跟蹤方位控制算法的流程圖。圖3.跟蹤高程控制算法的流程圖。3、太陽(yáng)跟蹤器的硬件設(shè)計(jì)圖4展示了一個(gè)擬議的太陽(yáng)跟蹤器方位跟蹤的硬件電路。的整個(gè)系統(tǒng)有兩個(gè)硬件電路與方位和仰角方向到驅(qū)動(dòng)器雙軸交流電機(jī)。發(fā)達(dá)國(guó)家的太陽(yáng)跟蹤器由三個(gè)模塊，是組成LDR基于傳感電路、比較器和電機(jī)的驅(qū)動(dòng)與繼電器。圖圖4.完全控制電路原理圖的太陽(yáng)跟蹤器方位跟蹤。圖圖6.開環(huán)比較器電壓傳輸特性。ccKiLDR-bsiedtirunilCompjaral:orMolordriverwitharelayCm甌idiccKiLDR-bsiedtirunilCompjaral:orMolordriverwitharelayCm甌idi[④DlU]-3fiL3ACtixnotP￥itiverttr3.1.基于LDR的傳感電路若要跟蹤陽(yáng)光，就必須感覺(jué)到的位置，和太陽(yáng)光電所需傳感器。擬議的太陽(yáng)跟蹤器使用光電傳感器的自標(biāo)定。LDR光敏電阻是可變電阻器的電阻取決于光的強(qiáng)度或落上它。低劑量輻射電阻隨入射光強(qiáng)度增加。第一次所示部分圖4的LDR傳感器是電壓分壓器電路的一部分，使輸出電壓。3.1.1.太陽(yáng)能的傳感裝置文中建立異地用圓柱的樹蔭下，作為太陽(yáng)敏感器的太陽(yáng)追蹤器。圖5顯示設(shè)計(jì)了太陽(yáng)能的傳感裝置，其包括四象限LDR傳感器和缸安裝在一塊木頭上。太陽(yáng)能的遙感設(shè)備被連接到光伏面板。東/西LDR和南/北LDR分別用于檢測(cè)方位運(yùn)動(dòng)及高程運(yùn)動(dòng)的光伏面板。光傳感器的設(shè)計(jì)基于陰影的使用。如果光伏面板不是垂直于陽(yáng)光下，氣缸的陰影會(huì)覆蓋一個(gè)或兩個(gè)異地和這會(huì)導(dǎo)致不同的光照強(qiáng)度，以收到的傳感裝置。圖5.太陽(yáng)能與四象限LDR傳感器的傳感裝置。3.1.2.創(chuàng)建反饋誤差電壓在圖4的第一部分，提出了一種用于創(chuàng)建誤差電壓簡(jiǎn)單的電子電路。它可以看出相應(yīng)LDR時(shí)，將降低電壓分壓器的輸出電壓蒙上了陰影。如果點(diǎn)燃了一個(gè)傳感器，另一種是陰影，差動(dòng)放大器放大它們之間的差電壓。反饋誤差電壓可以表示為：

R工■-J?i.艮R="t__可'小十瓦）礙+輕"—⑴它可以重新排列，如下所示：如果西方LDR如果西方LDR是灰色，'〔二-"3.2.比較器比較器的主要功能是充當(dāng)一個(gè)開關(guān)來(lái)打開中繼和旋轉(zhuǎn)電機(jī)。A比較器是本質(zhì)上是一個(gè)運(yùn)算放大器（運(yùn)放）操作在開環(huán)配置中，將一個(gè)時(shí)變的模擬信號(hào)轉(zhuǎn)換成二進(jìn)制輸出。第二部分中所示圖4，比較器被為了比較具有兩個(gè)門限值的誤差電壓。的門檻值被定義為輸入電壓，輸出的變化狀態(tài)。如中所示圖4有兩個(gè)門限值，作為給出：⑶"蔬％）⑷比較器的輸出是高飽和的狀態(tài)VH或VL低飽和的狀態(tài)。飽和VH和VL的輸出電壓可分別接近電源電壓+VCC和VCC。的然后，如下所示表示產(chǎn)出的比較：?jiǎn)?VHrElFn^Thl=叫fbrvFRt<耳爪丫陽(yáng)=%forv￡Jr>V斑toi?￡BPV殲肥比較器理想運(yùn)算放大器的電壓傳輸特性圖6所示。它注意到跟蹤系統(tǒng)的靈敏度由是的閾值通過(guò)可變電阻R4跟蹤精度調(diào)整。隨著R4的減小，跟蹤精度越高。然而，系統(tǒng)跟蹤響應(yīng)將變得越來(lái)越振蕩。3.3.電機(jī)驅(qū)動(dòng)與繼電器圖4的最后部分所示，它指出，電機(jī)驅(qū)動(dòng)電路與繼電器包括兩個(gè)達(dá)林頓對(duì)提供更多的電流增益和激勵(lì)繼電器。如果西方LDR是陰影，反饋誤差電壓視圖生成。當(dāng)vEW>VThl>VTh2,比較器輸出vpe數(shù)據(jù)和vPW分別走高、低飽和的電壓。晶體管Q1和Q2將因此，行為和第3季度和4季度處于截止?fàn)顟B(tài)。談到圖4晶體管Q1和Q2在提出主動(dòng)模式中，操作和輸入的電流或基極電流的Q1是：其中VBE是前偏基極-發(fā)射極電壓對(duì)雙極晶體管。因此，輸出當(dāng)前可以寫成：Q=—機(jī)=%十爲(wèi)〔1十嘰=［如—區(qū)L角％=AA5（8）參數(shù)1B和2B是共發(fā)射極雙極晶體管的電流增益。繼電器被激活的輸出電流，并通常開放接觸a1關(guān)閉。在這種情況下，跟蹤電機(jī)在方位方向順時(shí)針旋轉(zhuǎn)并因此光伏面板將向東移動(dòng)到面對(duì)太陽(yáng)。更具體地說(shuō)，太陽(yáng)跟蹤器嘗試調(diào)整光伏面板這樣所有電壓由異地幾乎相等，并平衡。其結(jié)果是，光伏面板幾乎是垂直于陽(yáng)光下，具有高能源發(fā)電。4、結(jié)論本文介紹了一些簡(jiǎn)單功能和簡(jiǎn)單控件完成實(shí)現(xiàn)采用雙軸交流電機(jī)的太陽(yáng)跟蹤器，跟隨太陽(yáng)和使用獨(dú)立的光伏逆變器電源來(lái)支撐整個(gè)系統(tǒng)。提出的一個(gè)電機(jī)設(shè)計(jì)是簡(jiǎn)單和自包含的并不需要編程和計(jì)算機(jī)接口。已成功地建立和測(cè)試實(shí)驗(yàn)室原型驗(yàn)證控件實(shí)現(xiàn)的有效性。實(shí)驗(yàn)結(jié)果表明，開發(fā)的系統(tǒng)增加了能量增益達(dá)28.31%為晴間多云的一天。擬議的方法是到目前為止最為創(chuàng)新的。它實(shí)現(xiàn)了以下有吸引力的功能：（1）控制簡(jiǎn)單和符合成本效益。（2）獨(dú)立的光伏逆變器電源支撐整個(gè)系統(tǒng)。（3）能夠移動(dòng)同時(shí)在其各自的范圍之內(nèi)，這兩根軸。（4）能夠調(diào)整跟蹤精度。（5）適用于移動(dòng)平臺(tái)上的太陽(yáng)跟蹤器。以上的實(shí)證研究結(jié)果使我們相信這些研究工作能提供給我們一些好的太陽(yáng)能產(chǎn)品開發(fā)的啟示。DesignandImplementationofaSun

TrackerwithaDual-AxisSingleMotorforanOpticalSensor-Based

PhotovoltaicSystemAbstract:Thedualthreatsofenergydepletionandglobalwarmingplacethedevelopmentofmethodsforharnessingrenewableenergyresourcesatthecenterofpublicinterest.Solarenergyisoneofthemostpromisingrenewableenergyresources.Suntrackerscansubstantiallyimprovetheelectricityproductionofaphotovoltaic(PV)system.Thispaperproposesanoveldesignofadual-axissolartrackingPVsystemwhichutilizesthefeedbackcontroltheoryalongwithafour-quadrantlightdependentresistor(LDR)sensorandsimpleelectroniccircuitstoproviderobustsystemperformance.Theproposedsystemusesauniquedual-axisACmotorandastand-alonePVinvertertoaccomplishsolartracking.Thecontrolimplementationisatechnicalinnovationthatisasimpleandeffectivedesign.Inaddition,ascaled-downlaboratoryprototypeisconstructedtoverifythefeasibilityofthescheme.TheeffectivenessoftheSuntrackerisconfirmedexperimentally.Toconclude,theresultsofthisstudymayserveasvaluablereferencesforfuturesolarenergyapplications.Keywords:dual-axisSuntracker;photovoltaicpanel;feedbackcontroltheory;lightdependentresistor;stand-alonePVinverter;energygain1.IntroductionWiththerapidincreaseinpopulationandeconomicdevelopment,theproblemsoftheenergycrisisandglobalwarmingeffectsaretodayacauseforincreasingconcern.Theutilizationofrenewableenergyresourcesisthekeysolutiontotheseproblems.Solarenergyisoneoftheprimarysourcesofclean,abundantandinexhaustibleenergy,thatnotonlyprovidesalternativeenergyresources,butalsoimprovesenvironmentalpollution.Themostimmediateandtechnologicallyattractiveuseofsolarenergyisthroughphotovoltaicconversion.ThephysicsofthePVcell(alsocalledsolarcell)isverysimilartotheclassicalp-njunctiondiode.ThePVcellconvertsthesunlightdirectlyintodirectcurrent(DC)electricitybythephotovoltaiceffect[1,2].APVpanelormoduleisapackagedinterconnectedassemblyofPVcells.InordertomaximizethepoweroutputfromthePVpanels,oneneedstokeepthepanelsinanoptimumpositionperpendiculartothesolarradiationduringtheday.Assuch,itisnecessarytohaveitequippedwithaSuntracker.Comparedtoafixedpanel,amobilePVpaneldrivenbyaSuntrackermayboostconsistentlytheenergygainofthePVpanel.SolartrackingisthemostappropriatetechnologytoenhancetheelectricityproductionofaPVsystem.Toachieveahighdegreeoftrackingaccuracy,severalapproacheshavebeenwidelyinvestigated.Generally,theycanbeclassifiedaseitheropen-looptrackingtypesbasedonsolarmovementmathematicalmodelsorclosed-looptrackingtypesusingsensor-basedfeedbackcontrollers[3-5].Intheopen-looptrackingapproach,atrackingformulaorcontrolalgorithmisused.Referringtotheliterature[6-10],theazimuthandtheelevationanglesoftheSunweredeterminedbysolarmovementmodelsoralgorithmsatthegivendate,timeandgeographicalinformation.Thecontrolalgorithmswereexecutedinamicroprocessorcontroller[11,12].Intheclosed-looptrackingapproach,variousactivesensordevices,suchaschargecoupledevices(CCDs)[13-15]orlightdependentresistors(LDRs)[12,16-19]wereutilizedtosensetheSun'spositionandafeedbackerrorsignalwasthengeneratedtothecontrolsystemtocontinuouslyreceivethemaximumsolarradiationonthePVpanel.Thispaperproposesanempiricalresearchapproachonthisissue.Solartrackingapproachescanbeimplementedbyusingsingle-axisschemes[12,19-21],anddual-axisstructuresforhigheraccuracysystems[16-18,22-27].Ingeneral,thesingle-axistrackerwithonedegreeoffreedomfollowstheSun'smovementfromtheeasttowestduringadaywhileadual-axistrackeralsofollowstheelevationangleoftheSun.Inrecentyears,therehasbeenagrowingvolumeofresearchconcernedwithdual-axissolartrackingsystems.However,intheexistingresearch,mostofthemusedtwosteppermotors[22,23]ortwoDCmotors[16,17,24,25]toperformdual-axissolartracking.Withtwotrackingmotorsdesigns,twomotorsweremountedonperpendicularaxes,andevenalignedthemincertaindirections.Insomecases,bothmotorscouldnotmoveatthesametime[5].Furthermore,suchsystemsalwaysinvolvecomplextrackingstrategiesusingmicroprocessorchipsasacontrolplatform.Inthiswork,employingadual-axiswithonlysingletrackingmotor,anattempthasbeenmadetodevelopandimplementasimpleandefficientcontrolscheme.ThetwoaxesoftheSuntrackerwereallowedtomovesimultaneouslywithintheirrespectiveranges.Utilizingconventionalelectroniccircuits,noprogrammingorcomputerinterfacewasneeded.Moreover,theproposedsystemusedastand-alonePVinvertertodrivemotorandprovidepowersupply.Thesystemwasself-containedandautonomous.ExperimentresultshavedemonstratedthefeasibilityofthetrackingPVsystemandverifiedtheadvantagesoftheproposedcontrolimplementation.Theremainderofthearticleisorganizedinthefollowingmanner:Section2describesthetrackingstrategiesofthedevelopedclosed-loopsolartrackingsysteminwhichasensor-basedfeedbackcontrollerisused.ThedetailedarchitectureoftheSuntrackerhardwareisproposedinSection3.InSection4,ascaled-downlaboratoryprototypeisbuiltandtested.Finally,themainconclusionsofthisworkaredrawninSection5.2.DevelopedClosed-LoopSolarTrackingSystemTheblockdiagramofthedevelopedclosed-loopsolartrackingsystemisillustratedinFigure1,describingthecompositionandinterconnectionofthesystem.Fortheclosed-looptrackingapproach,thesolartrackingproblemishowtocausethePVpanellocation(output)tofollowthesunlightlocation(input)ascloselyaspossible.Thesensor-basedfeedbackcontrollerconsistsoftheLDRsensor,differentialamplifier,andcomparator.Inthetrackingoperation,theLDRsensormeasuresthesunlightintensityasareferenceinputsignal.TheunbalanceinvoltagesgeneratedbytheLDRsensorisamplifiedandthengeneratesafeedbackerrorvoltage.TheerrorvoltageisproportionaltothedifferencebetweenthesunlightlocationandthePVpanellocation.Atthistimethecomparatorcomparestheerrorvoltagewithaspecifiedthreshold(tolerance).Ifthecomparatoroutputgoeshighstate,themotordriverandarelayareactivatedsoastorotatethedual-axis(azimuthandelevation)trackingmotorandbringthePVpaneltofacetheSun.Accordingly,thefeedbackcontrollerperformsthevitalfunctions:PVpanelandsunlightare

constantlymonitoredandsendadifferentialcontrolsignaltodrivethePVpaneluntiltheerrorvoltageislessthanapre-specifiedthresholdvalue.Figure1.Blockdiagramofthesolartrackingsystem.ThesystemtrackstheSunautonomouslyinazimuthandelevationangles.ThewholeworkingalgorithmsaresummedupintheflowchartsshowninFigures2and3.ThesunlightintensityfromfourdifferentdirectionsismeasuredbytheLDR-basedsensingcircuit.ThevoltagesvE,vW,vSandvNaredefinedasthesensingvoltagesproducedbytheeast,west,south,andnorthLDRsrespectively.InanattempttodrawmaximumpowerfromthePVpanel,theazimuthandelevationtrackingprocessescansimultaneouslyproceeduntilthePVpanelisalignedorthogonallytothesunlight.Thetrackerinstallationisnotrestrictedtothegeographicallocation.Figure2.Flowchartoftrackingalgorithmforazimuthcontrol.ST.AKTTnK：lir!i|LFKDFigure2.Flowchartoftrackingalgorithmforazimuthcontrol.ST.AKTTnK：lir!i|LFKDilu■沁s￡lhccurtiikIwealI.RfbilumiluRI15ohtndFTKWVmnurruD-J-AgnJ7-imistridaj*nvidI'umLhcKliyolCnaHFigure3.Flowchartoftrackingalgorithmforelevationcontrol.

r9f4nparrihrli|4ilinlrmil^lkMidi4ldfKflhLPH1rdr9f4nparrihrli|4ilinlrmil^lkMidi4ldfKflhLPH1rd卻閒pZmgurnoiiTMiihu-adTirnIIkrcbr|i<nnail!*耶附pnThhTV^ITimihcncbi^nlTnxlfJrpmrirf3.SunTrackerHardwareDesignFigure4presentsoneofthehardwarecircuitsoftheproposedSuntrackerforazimuthtracking.Theentiresystemhastwohardwarecircuitswithbothofazimuthdirectionandelevationdirectiontodrivethedual-axisACmotor.ThedevelopedSuntrackeriscomprisedofthreemodules,whicharetheLDR-basedsensingcircuit,comparatorandamotordriverwitharelay.Figure4.CompletecontrolcircuitdiagramoftheSuntrackerforazimuthtracking.LDR-baiedsjtntiiigfiirnilCornpMratarMolardriverudtharelayFigure4.CompletecontrolcircuitdiagramoftheSuntrackerforazimuthtracking.LDR-baiedsjtntiiigfiirnilCornpMratarMolardriverudtharelayLDR-BasedSensingCircuitTotrackthesunlight,itisnecessarytosensethepositionoftheSunandforthatanelectro-opticalsensorisneeded.TheproposedSuntrackerusestheelectro-opticalsensorforself-calibration.ALDRorphotoresistorisavariableresistorwhoseelectricalresistancedependsontheintensityofthelightfallingonit.TheLDRresistancedecreaseswithincidentlightintensityincreasing.AsseeninthefirstpartofFigure4,theLDRsensorisapartofthevoltagedividercircuitinordertogiveanoutputvoltage.SolarSensingDeviceThepapercreatesaSuntrackerusingLDRswithacylindricalshadeasaSunsensor.Figure5showsthedesignedsolarsensingdevice,whichcomprisesafour-quadrantLDRsensorandacylindermountedonawood-block.ThesolarsensingdeviceisattachedtothePVpanel.TheEast/WestLDRandtheSouth/NorthLDRarerespectivelyusedinthedetectionofazimuthmotionandelevationmotionofthePVpanel.Thedesignofthelightsensorisbasedontheuseoftheshadow.IfthePVpanelisnotperpendiculartothesunlight,theshadowofthecylinderwillcoveroneortwoLDRsandthiscausesdifferentlightintensitytobereceivedbythesensingdevice.Figure5.Solarsensingdevicewithafour-quadrantLDRsensor.CreatingFeedbackErrorVoltageThesimpleelectroniccircuitforcreatingerrorvoltageispresentedinthefirstpartofFigure4.ItcanbeseenthattheoutputvoltageofthevoltagedividerwillbelowerwhenthecorrespondingLDRisshadowed.Ifonesensorislightedandtheotherisshadowed,thedifferentialamplifieramplifiesthedifferencevoltagebetweenthem.Thefeedbackerrorvoltagecanbeexpressedas:7?ReKRnF—耳5++瓦）礙十陋"whichcanberearrangedasfollows:IfthewestLDRisshaded,'-''廣―-比ComparatorThemainfunctionofthecomparatoristoactasaswitchtoturnontherelayandrotatethemotor.Acomparatorisessentiallyanoperationalamplifier(op-amp)operatedinanopen-loopconfiguration,whichconvertsatime-varyinganalogsignalintoabinaryoutput.AsdepictedinthesecondpartofFigure4,thecomparatorisdesignedtocomparetheerrorvoltagewithtwothresholdvalues.Thethresholdvalueisdefinedastheinputvoltageatwhichtheoutputchangesstates.AsshowninFigure4,therearetwothresholdvalueswhicharegivenas:⑶（4）TheoutputofthecomparatorisahighsaturatedstateVHoralowsaturatedstateVL.ThesaturatedoutputvoltagesVHandVLmaybeclosedtothesupplyvoltages+VCCandVCC,respectively.Thecomparatoroutputsarethenexpressedasfollows:VFE=『ft血VETF>^Thl二VLforvFFT.<V7hl「FFT=拖IT耐二嶺壯二VHtOLT胡「VVmThevoltagetransfercharacteristicsofthecomparatorwithidealop-ampsareshowninFigure6.Itisnotedthatthesensitivityforthetrackingsystemisdominatedbythethresholdvalues,whichareadjustedbythevariableresistorR4accordingtothetrackingaccuracy.AsR4decreases,thetrackingaccuracyincreases.However,thesystemtrackingresponsewillbecomeincreasinglyoscillatory.Figure6.Voltagetransfercharacteristicsoftheopen-loopcomparator.MotorDriverwithaRelayAsseeninthelastpartofFigure4,itisobservedthatthedesignedmotordriverwitharelayconsistsoftwoDarlingtonpairsthatprovideincreasedcurrentgainandactuatetherelay.IfthewestLDRisshaded,afeedbackerrorvoltagevEWisgenerated.WhenvEW>VTh1>VTh2,thecomparatoroutputsvPEandvPWgohighandlowsaturatedvoltagesrespectively.ThetransistorsQ1andQ2willthereforeconductandQ3andQ4areinthecutoffstate.ReferringtoFigure4,transistor