光伏晶体硅表面陷光结构及铣削成型研究

发布时间：2018-03-13 11:34

本文选题：光伏晶体硅　切入点：陷光结构　出处：《山东大学》2017年硕士论文　论文类型：学位论文

【摘要】：太阳能是一种清洁、可持续利用能源,充分利用太阳能是解决能源危机、保证现代工业可持续发展的有效途径。太阳能光伏发电是将太阳能转化为电能的重要技术手段,但光电转换效率低是制约太阳能光伏发电的技术瓶颈。光伏晶体硅太阳能电池利用晶体硅片表面陷光结构的绒貌使光多次反射,从而减少光的反射损耗,提高光能的利用率。因此,晶体硅表面绒貌对光电转换极其重要。本文以正向金字塔结构作为光伏晶体硅表面的陷光结构,考虑结构成型加工工艺影响,计算确定了优化后的陷光结构参数。在晶体硅机械加工材料去除机理分析的基础上,对金字塔结构的机械加工成型进行了模拟分析,并进行了金字塔结构微铣削加工成型实验研究,研究工作对太阳能光伏晶体硅表面陷光结构机械加工成型技术的发展具有重要意义。本文的主要工作如下:(1)提出了基于射线追踪法的光伏晶体硅表面光线加权反射率计算方法,计算分析了光伏晶体硅表面金字塔陷光结构及结构参数对陷光效果的影响规律,得到了较优的金字塔陷光结构参数和入射光线角度。通过计算碱腐蚀法制得的典型金字塔绒面的加权反射率,对计算方法进行了验证;针对金字塔陷光结构,利用数值计算的方法跟踪每一条光线的反射行程,计算了整束光线的加权反射率;以金字塔底角、塔尖圆角半径、结构高度等作为主要结构参数,分析了金字塔陷光结构参数对加权反射率和陷光效果的影响规律,提出了较优的金字塔陷光结构参数和最佳入射光线角度。陷光结构的高度对反射率的影响很小,陷光效果随金字塔底角的增大而提高,随塔尖圆角的增大而降低,其中塔尖圆角对陷光效果的影响较大,金字塔陷光结构对垂直入射的光线拥有最好的陷光效果。(2)建立了光伏晶体硅表面陷光结构微铣削加工的有限元模型,对微铣削加工过程进行了二维和三维仿真分析,研究了工艺参数对切削力和材料去除模式的影响。二维铣削加工仿真结果表明,单晶硅材料的脆塑转变厚度为120nm左右,进给速度的增大会导致切削力明显增大,主轴转速和铣削深度对切削力的影响较小。三维铣削加工仿真结果表明,在特定的工艺参数下,可以实现单晶硅的塑性去除模式。(3)实验研究了硬质合金微铣刀铣削加工光伏晶体硅表面了V型槽阵列和金字塔结构的制备工艺。在五轴联动高速微细加工中心上,采用硬质合金微细铣刀进行了光伏晶体硅表面V型槽和金字塔陷光结构的铣削加工成型实验,制备了不同深度的V型槽和金字塔结构,并分析检测了V型槽和金字塔结构的加工质量。实验结果表明V型槽质量受铣削深度影响很小,而制得的金字塔结构存在非常突出的崩塌现象,微细铣刀磨损、破损严重,有待进一步研究改进。
[Abstract]:Solar energy is a clean, sustainable use of energy, the full use of solar energy is an effective way to solve the energy crisis and ensure the sustainable development of modern industry. Solar photovoltaic power generation is an important technical means to convert solar energy into electric energy. However, the low efficiency of photovoltaic conversion is the technical bottleneck of solar photovoltaic power generation. Photovoltaic crystal silicon solar cells can reduce the reflection loss of light by making use of the plush features of the trapping structure on the surface of the crystal silicon wafer to make the light reflect many times. Therefore, the surface velvet appearance of crystalline silicon is very important for photoelectric conversion. In this paper, the forward pyramid structure is used as the trapping structure of silicon surface of photovoltaic crystal, and the influence of structure forming process is considered. The parameters of the optimized trapping structure are calculated and determined. Based on the analysis of the material removal mechanism of the crystal silicon machining, the machining molding of the pyramid structure is simulated and analyzed. And the experimental study of micro-milling with pyramid structure was carried out. The research work is of great significance to the development of mechanical processing technology for silicon surface trapping structure of solar photovoltaic crystal. The main work of this paper is as follows: 1) A method for calculating the ray-weighted reflectance of silicon surface based on ray tracing method is proposed. The influence of the structure and structure parameters of the pyramid trapping light on the photovoltaic crystal silicon surface is calculated and analyzed. The optimum parameters of pyramid trapping light structure and incident light angle are obtained. The calculation method is verified by calculating the weighted reflectance of typical pyramidal villous surface obtained by alkali corrosion method. The reflection stroke of each ray is tracked by numerical calculation, and the weighted reflectivity of the whole beam is calculated, with the pyramid bottom angle, the radius of the tip corner and the height of the structure as the main structural parameters. The influence of pyramid trapping light structure parameters on weighted reflectivity and trapping light effect is analyzed. The optimum pyramid trapping light structure parameters and optimum incident light angle are proposed. The height of trapping light structure has little effect on reflectivity. The trapping effect increases with the increase of pyramid bottom angle and decreases with the increase of pyramid angle. The pyramidal trapping structure has the best trapping effect on the vertically incident light. The finite element model of photovoltaic crystal silicon surface trapping structure micro-milling is established, and the two-dimensional and three-dimensional simulation analysis of the micro-milling process is carried out. The effects of process parameters on cutting force and material removal mode are studied. The simulation results of two-dimensional milling show that the brittle plastic transition thickness of single crystal silicon is about 120 nm, and the increase of feed rate will result in obvious increase of cutting force. The effect of spindle speed and milling depth on cutting force is small. The plastic removal mode of monocrystalline silicon can be realized. The fabrication technology of V-groove array and pyramid structure on silicon surface of photovoltaic crystal processed by cemented carbide micro-milling cutter has been studied experimentally. The V-groove and pyramidal structure of photovoltaic crystal silicon surface were fabricated with cemented carbide micro-milling cutter, and the V-shaped groove and pyramid structure with different depth were prepared. The machining quality of V-groove and pyramidal structure is analyzed and tested. The experimental results show that the V-groove quality is very little affected by milling depth, while the pyramid structure has very prominent collapse phenomenon, and the micro-milling cutter is worn and damaged seriously. Further research and improvement are needed.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM914.41

【相似文献】