Engineering Application Research Of Equal Diameter Control System For Large Diameter Straight Pull Type Single Crystal Furnace

In recent years with the Solar Power fast growing, the single crystal silicon is used largely in this field. At present, the single crystal production equipment has already developed, but it also has something need to be improved. So the optimization of the single crystal production equipment is very important. It could not only improve quality of the single crystal silicon, but also reduce cost. Recently the diameter of single crystal silicon is required larger and larger.We Research on a control system for the full diameter of single crystal in CZ-Single crystal furnace, and we newly design both hardware and software of the control system. In this dissertation, the structure of CZ-Single crystal furnace is introduced firstly. Then the theory of control technique for the constant diameter of single crystal in CZ-Single crystal furnace is summarized. In hardware we improve the traditional driving mode, and also use the CCD to measure diameter. In software we use Fieldbus mode with CANopen. This makes network be digital, and the information processing be alive.The performance of control system for the constant diameter of single crystal affects the quality of single crystal silicon. In the whole process, the diameter of single crystal is affected mostly by the crystal pulling up speed and the temperature. However, pulling up speed and temperature make affect each other by the diameter. So, internal model control(IMC) is introduced to combine with PID to be IMC-PID controller. The basic principle of internal model control and the research process of IMC-PID controller are summarized. Simulations are done for the control method that the constant diameter of single crystal model is proposed by combining with IMC-PID controller. The result has satisfied the engineering application.