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直拉法单晶硅直径的控制难点在于过程对象的大惯性、大滞后、非线性及多干扰。采用双重控制思想,快则治标,主控制器快速调整拉晶速度,快速影响直径;缓则治本,副控制器平稳调整液面温度,保证产品质量。针对对象的惯性和滞后,结合预测PI控制算法,提出双重预测PI控制算法。算法简洁,结果表明,采用双重预测PI控制算法,能够协调控制拉晶速度和液面温度,兼顾系统快速性和产品质量。特别在液面温度的控制上,该算法可以提高系统的工作频率,平稳且快速调整液面温度。控制系统运行稳定,该算法具有实用价值。
Czochralski method of controlling the diameter of silicon is difficult to control the large inertia of the process object, large lag, nonlinear and more interference. Adopting double control idea, quick rule, the main controller quickly adjust the crystal pulling speed, quickly affect the diameter; slow rule, the deputy controller to adjust the liquid surface temperature to ensure product quality. In view of the inertia and lag of the object, combined with the predictive PI control algorithm, a dual predictive PI control algorithm is proposed. The algorithm is simple and concise. The results show that the dual predictive PI control algorithm can coordinate the crystal pulling speed and the liquid surface temperature, taking into account the rapidity of the system and product quality. Especially in the control of the liquid surface temperature, the algorithm can improve the working frequency of the system and adjust the liquid surface temperature smoothly and rapidly. The control system runs stably, this algorithm has the practical value.