Research Of High Quality Polysilicon Ingot Furnace And Its Control System

In the national "14th Five-Year Plan" and the long-term goal of 2035,it is clearly advocated to actively develop photovoltaic and other new energy industries.As a key production equipment in the photovoltaic industry,polysilicon ingot furnace plays an important role.The traditional polysilicon ingot furnace adopts a two-zones heating structure,the heating efficiency and the quality of the polysilicon ingot products are limited.The efficiency,accuracy and reliability of the control system need to be improved.In order to solve the above problems,a three-zones and six-sides heating structure is designed in this dissertation,and a popular transmission heat dissipation device is designed at the bottom of the graphite platform of the ingot furnace to improve the heating efficiency in the melting stage and the heat dissipation efficiency in the long crystal stage.Based on the independent heating structure,the control system algorithm is optimized,and the software and hardware are designed and tested.Main achievements of the dissertation are as follows:Firstly,the dissertation background and significance of polysilicon ingot furnace are expounded.The furnace structure,control system and its principle,and the development at home and abroad are summarized.The research status and development trend of polysilicon ingot furnace and its control system are introduced from the three aspects: thermal field structure,mathematical model and system control algorithm.Secondly,By analyzing the heat transfer process,performance and energy consumption of the heat field,and combined with the production process and requirements,a three-zones and six-sides heating structure is designed,and a hot transmission device is added at the bottom of the graphite platform.ANSYS is used for the thermal field simulation analysis software.Thirdly,the mathematical model of temperature and gas flow control is constructed,and a fuzzy controller is designed to solve the problems of nonlinearity and large lag of gas flow control objects.For the temperature control system,in order to automatically adjust the control parameters in the production process,a fuzzy PID controller is designed,and the quantitative factor and scale factor in the fuzzy PID temperature control are automatically optimized by Particle Swarm Optimization(PSO),so as to improve the control efficiency.In order to solve the problem of insufficient PSO search accuracy,a nonlinear decreasing inertial weight optimization algorithm is designed to improve the above temperature control deficiencies.Finally,MATLAB simulation is used to verify the control effect of the control system.Finally,the software and hardware design and experiment of the control system based on OPTO22 PAC are completed,and the reliability of the control system is improved by designing the interlocking and coordination strategy and the network redundant communication structure.The feeding test is carried out,and the analysis shows that the gas flow fuzzy control and NDWPSO fuzzy PID control are better based on the optimized three zone heating structure,and the product quality is further improved.