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1、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外文翻译Polycrystalline silicon solar
2、cell manufacture craft outlineAs we all know, solar energy has many advantages, photovoltaic power generation will provide the main energy for human beings, currently improve the photoelectric conversion efficiency of solar cells, reduce production costs can expand the market, solar cells have the f
3、ollowing: Monocrystalline silicon, polysilicon, ribbon silicon, film materials.From the industrial point of view, the center of gravity has been developed from single crystal to polycrystalline direction, the main reasons are; 1 There are fewer and more tail materials available for solar cells, 2 fo
4、r solar cells, square substrates are more cost-effective, 3 polysilicon production process continues to progress, 4 Nearly ten years of monocrystallineThe process technology of polysilicon battery is discussed in two aspects.2. Laboratory efficient battery ProcessLaboratory techniques typically stud
5、y ways and means to achieve maximum efficiency, providing the limits that can be achieved by specific materials and processes.2.1 about the absorption of lightFor light absorption is mainly:(1) Reduce surface reflection;(2) Change the path of light in the battery body;(3) Use back reflection.For mon
6、ocrystalline silicon, the method of anisotropic chemical corrosion can be used to make pyramidal suede structure on (100) surface to reduce surface light reflection.However, polysilicon Crystal deviation (100) surface, the above method can not make a uniform velvet surface, the following methods are
7、 used:1 Laser Groove By means of laser groove, the inverted pyramid structure can be made on the surface of polysilicon, and the reflectivity is 46% in the 500900nm spectrum range, The solar cells made by this method usually have a higher short-circuit current, but the open circuit voltage is not to
8、o high.2 Chemical grooves Using mask isotropic corrosion, this method can not form the kind of sharp conical structure formed by anisotropic corrosion. The Velvet formed by this method has obvious effect of reducing reflection on the range of 7001030 micron spectra. However, the mask layer generally
9、 has to be formed at a higher temperature, causing the performance of polysilicon material to decrease, and the life of less children is shortened.3 reactive ion corrosion (RIE) The method is a non-mask corrosion process, the formation of the suede reflectivity is particularly low, in the 4501000 Mi
10、cron spectral range of the reflectivity can be less than 2%.From an optical point of view alone, it is an ideal method, but there is a serious problem of silicon surface damage.4 Production of reflective film layer For efficient solar cells, the most common and effective method is the steaming ZnS/M
11、gF2 double-layer damping film, the optimum thickness of which depends on the thickness of the oxide layer below and the characteristics of the battery surface.2.2 Metallization TechnologyIn the production of high-efficiency batteries, the general area of laboratory batteries is relatively small, so
12、the need for fine metal grid lines, the general use of methods for lithography, electron beam evaporation, electronic plating.Electron beam evaporation and electroplating: In general, a Ti/Pa/Ag multilayer metal electrode is steamed and plated by using a positive adhesive stripping process. The disa
13、dvantage is that the electron beam evaporation causes the silicon surface/passivation layer interface damage, causes the surface compounding to increase, in the process, uses the tunnel junction contact method, in the silicon and the metal formation a thinner oxide layer, should work hard function l
14、ow metal (such as titanium, etc.) can sense a stable electron accumulation layer on the silicon surface.Another method is to open a small window on the passivation layer and deposit the metal grating line to form a mushroom-like-shaped electrode.Formation technique of 2.3 PN Junction1 Launch area fo
15、rmation and phosphorus suction For efficient solar cells, the formation of the launch area generally adopts the selective diffusion, which forms the heavy impurity area under the metal electrode and realizes the shallow concentration diffusion between the electrodes.Diffusion methods: Diffusion plus
16、 corrosion and burial diffusion processes. For Mc-si materials, the long period of phosphorus suction process (usually 3-4 hours) can increase the diffusion length of some Mc-si by two orders of magnitude. In the effect of substrate concentration on suction多晶硅太阳能电池制作工艺的阐述正如我们所家喻户晓的，太阳能电池有许多的优点。从近几年的数据可得，能够提供主要能源的是光伏发电，目前提高太阳电池的光电转换效率成为一个首要问题，方法是降低生产成本。降低成本不仅仅可以很大程度上提高太阳电池的光电转换
