碟式聚光器镜面单元聚焦光斑与位姿误差的关联特性

Correlative Characteristics Between Focal Spot of Solar Dish Concentrator Mirror Unit and Posture Error

为实现碟式聚光器镜面单元调焦的定量指导,需要建立镜面单元空间位姿与聚焦光斑特征的唯一定量对应关系。提出以镜面单元旋转和平移运动的组合等效引入位姿误差,基于光线跟踪方法建立位姿误差工况的聚焦光斑分布模型,引入聚光比阈值来提取聚焦光斑的特征边界,并采用最小二乘法对特征边界进行椭圆拟合,用于表征聚焦光斑的分布特征。分析了太阳直射辐照值、边界提取阈值、镜面单元位姿误差等对聚焦光斑特征的影响。结果表明,镜面单元位姿误差工况不同时,聚焦光斑的椭圆几何特征具有明显可区分性,用于镜面单元位姿反演具有可行性,为镜面单元调焦系统的搭建提供了参考。

In order to realize the quantitative guidance for the focusing of dish concentrator mirror unit,it is essential to establish the unique quantitatively corresponding relationship between the mirror unit posture and the focal spot feature.We have presented the equivalent posture error by combining rotation and translation movement of the mirror unit,and the focal spot flux density distribution model under the posture error condition is established based on the ray tracing method.The concentration ratio threshold is applied to extracting the boundary characteristics of the focal spot,and the least-squares method is used for elliptical fitting of the boundary characteristics which represents the distribution characteristics of the focal spot.The factors influencing the focal spot characteristics are analyzed,including the direct normal solar irradiation,concentrator ratio threshold,and mirror unit posture error.The results show that the ellipse geometry of the focal spot under different mirror unit posture error conditions can be obviously distinguished,and it is feasible for the mirror unit posture inversion,which provides reference for the construction of the subsequent mirror unit focusing system.