Electrothermal Furnace’s Intelligent Temperature Control System Based On Fuzzy PID

The electrothermal furnace is one kind of device which is widely used in heat treatment production of industry. Its temperature control has the characteristics such as changing slowly, pure time delay and non-linearity. So it is difficult to obtain a precise mathematical model and to determine parameters by using mathematics method. When we need high precision requests of temperature control, it is difficult achieve the ideal control effect by using the traditional control theories and method. Therefore, this thesis took the singlechip as core processor, and developed an excellent quality and reasonable price temperature control systems based on fuzzy PID. This method can get higher precision of temperature control, economic energy and higher reliability.In this thesis, the method and the development condition of furnace temperature control at home and abroad were presented. And the content and the significance of this thesis were discussed. On the basis of the analysis of the industrial production process and requirements, an intelligent temperature control system of the electrothermal furnace used fuzzy control is built. Then, the control system hardware, control algorithm and software realization has carried on the detailed design and analysis. This research work focuses mainly on hardware design and software design, as well as the fuzzy PID control algorithm design and simulation. The main work is stated as follows:In the hardware design, each circuit in every part of this system in detail is given, and the working principle of the circuit is discussed. Adopted the microprocessor AT89C52as the core processor, the thesis has mainly introduced the design method of the temperature detection unit and control unit. The system applied RS-232serial port circuit, in order to communicate between the temperature control system and PC. Furthermore, other peripheral circuits such as the PWM control output channel, control panel, and alarm circuit are also been designed.In software design, the system control software and program for all the functions were provided. The system has developed such application programs as temperature detection module, fuzzy PID control algorithm, RS-232serial port module and LED module.This thesis simulated analysis the conventional PID, fuzzy control and fuzzyPID control method by using MATLAB tool. Experimental results illustrate that the PID control is used in the system, regulating time and overshoot always cannot achieve the specification.When fuzzy control is used, regulating time and overshoot always can achieves the specification, but system cause a larger steady-state error. So it comes to a new method of combining them together. The parameters of Kp, Ki and Kd are adjusted by fuzzy inference. It turned out that fuzzy PID control can work effectively. The method of fuzzy PID control is an ideal method to the temperature of the electrothermal furnace. The fuzzy PID controller achieved the technology requirements of the system which are:the system must be stable, regulating time must be short, and overshoot must be small.Finally, introduce the design of communication control interface for the system and PC, the design of communication protocol and communication program.