xxxxxxxxxx毕业设计说明书（论文）xxxxxxxx毕业实践任务书课题名称恒压供水的PLC控制系统指导老师xxx职称xx专业名称xxxxxxxxxxxxx班级xxxxxxxxxxxxxxx学生姓名xx学号xxxxxxxxx课题需要完成的任务：恒压供水的基本思路是当用水量大时，增加水泵数量或提高水泵的转动速度以保持管网中的的水压不变，用水量小时做出相反的动作。系统主要由变频器，PLC、水泵、压力传感器四部分组成长。水压传感器将水压的变化转变为电流或电压的变化送给EM235模块，转换成数字量信号后送给PLC，通过PID控制，输出送给EM235模块，转换成模拟量信号后，送给变频器，由变频器来控制水泵的转动速度。主要完成任务如下：（1）PID控制器的程序设计（2）西门子PLC模拟量扩展模块的程序设计（3）变频器控制的程序设计生产过程自动化技术课题计划：x.x~x.x熟悉课题，准备资料；x.x~x.x设计硬件；x.x~x.x作图，编制程序；x.x~x.x程序调试；x.x~x.x编写毕业设计论文；x.x~x.x准备毕业答辩。计划答辩时间：xxxx年x月x日~x日xxxxxxxxxx（分院、系部）xxxx年x月xx日外文翻译PolycrystallinesiliconsolarcellmanufacturecraftoutlineAsweallknow,solarenergyhasmanyadvantages,photovoltaicpowergenerationwillprovidethemainenergyforhumanbeings,currentlyimprovethe-1-xxxxxxxxxx毕业设计说明书（论文）photoelectricconversionefficiencyofsolarcells,reduceproductioncostscanexpandthemarket,solarcellshavethefollowing:Monocrystallinesilicon,polysilicon,ribbonsilicon,filmmaterials.Fromtheindustrialpointofview,thecenterofgravityhasbeendevelopedfromsinglecrystaltopolycrystallinedirection,themainreasonsare;[1]Therearefewerandmoretailmaterialsavailableforsolarcells,[2]forsolarcells,squaresubstratesaremorecost-effective,[3]polysiliconproductionprocesscontinuestoprogress,[4]NearlytenyearsofmonocrystallineTheprocesstechnologyofpolysiliconbatteryisdiscussedintwoaspects.2.LaboratoryefficientbatteryProcessLaboratorytechniquestypicallystudywaysandmeanstoachievemaximumefficiency,providingthelimitsthatcanbeachievedbyspecificmaterialsandprocesses.2.1abouttheabsorptionoflightForlightabsorptionismainly:(1)Reducesurfacereflection;(2)Changethepathoflightinthebatterybody;(3)Usebackreflection.Formonocrystallinesilicon,themethodofanisotropicchemicalcorrosioncanbeusedtomakepyramidalsuedestructureon(100)surfacetoreducesurfacelightreflection.However,polysiliconCrystaldeviation(100)surface,theabovemethodcannotmakeauniformvelvetsurface,thefollowingmethodsareused:[1]LaserGrooveBymeansoflasergroove,theinvertedpyramidstructurecanbemadeonthesurfaceofpolysilicon,andthereflectivityis4~6%inthe500~900nmspectrumrange,Thesolarcellsmadebythismethodusuallyhaveahighershort-circuitcurrent,buttheopencircuitvoltageisnottoohigh.[2]ChemicalgroovesUsingmaskisotropiccorrosion,thismethodcannotformthekindofsharpconicalstructureformedbyanisotropiccorrosion.TheVelvetformedbythismethodhasobviouseffectofreducingreflectionontherangeof700~1030micronspectra.However,themasklayergenerallyhastobeformedatahighertemperature,causingtheperformanceofpolysiliconmaterialtodecrease,andthelifeoflesschildrenisshortened.[3]reactiveioncorrosion(RIE)Themethodisanon-maskcorrosionprocess,theformationofthesuedereflectivityisparticularlylow,inthe450~1000Micronspectralrangeofthereflectivitycanbelessthan2%.Fromanopticalpointofviewalone,itisanidealmethod,butthereisaseriousproblemofsiliconsurfacedamage.[4]ProductionofreflectivefilmlayerForefficientsolarcells,themostcommonandeffectivemethodisthesteamingZnS/MgF2double-layerdampingfilm,theoptimumthicknessofwhichdependsonthethicknessoftheo...
