Research On Solar Cell Visual Alignment System

With the rapid development of the solar power industry,the market demanded higher and higher performance and quality of photovoltaic modules.As an important component in the production of photovoltaic modules,deviations in the angle and position of solar cells will have impacts on modules’ photovoltaic conversion rate and service life.To solve these problems,the visual alignment system is used to align the cells to improve the accuracy of series welding.This paper will study the solar cell visual alignment system from modules series welding process,combining the image processing algorithm and the kinematic characteristics of the UVW alignment platform.Based on the visual alignment system’s working processes and series welding accuracy requirements,the solution for cells deviation measurement and elimination are designed.To improve measurement efficiency,the chunk segmentation and image pyramids methods are uesd to reduce the number of templates and data size,which reduces the ROI(Region of Interest)detection time to 0.083s;to improve measurement accuracy,the Scharr operator,the minimum inter-class variance,Gaussian fitting and total least squares are used for edge detection and fitting to achieve sub-pixel accuracy;to eliminate the deviation smoothly,the kinematic characteristics of UVW alignment platform’s position positive and negative solution formulas,singular position shape,xyθ three-dimensional working space,are analyzed.For the synchronous constant velocity method which exists problems that the change of rotation angle θ could lead to the bending of the platform trajectory and the slowing down of the speed,the equal angular velocity instantaneous center method which eliminates the influence on the motion speed made by rotation angle θ,and keeps the platform moving at a uniform speed during alignment was designed.Finally,based on the hardware equipment,deviation measurement and UVW alignment platform trajectory planning scheme,the system hardware is connected,image acquisition,display,processing,alignment platform motion control and other software functions are completed.Through the experimental test,it can be seen that after using this system to perform alignment,the solar cell position deviation is less than 9μm and the angle deviation is less than 0.07°,meeting the precise requirements of string welding.