电阻加热炉（Resistance heating furnace）.doc

电阻加热炉（Resistance heating furnace） One, foreword Automatic control system is widely used in various fields, especially in industry. Temperature control is one of the most common control types in the control system. With the rapid development of single chip microcomputer, the control of the controlled object is becoming an important trend in the field of automatic control. The design requires a single-chip microcomputer to design an electric furnace temperature control system. The characteristics of electric furnace temperature control system The temperature control system consists of four parts: temperature sensor, temperature regulator, actuator, and controlled object. The system structure diagram is shown in figure 1. The controlled object is the thermal furnace temperature object of large capacity and large inertia, which is a typical multi-order volume delayed characteristic, which is often approximated to include the second volume of the second volume with pure lag. Due to the large capacity of the controlled object, the actuator of the controllable silicon is usually adopted as the actuator, and its specific circuit diagram is shown in figure 2. The characteristics of the actuator: the temperature regulation of the electric furnace is through the intermittent action of the regulator (power supply), and the ratio of the time Tb of the closed time of the electric furnace to the time of disconnection is alpha, alpha = Tb/Tk. To regulate the temperature of the heating furnace, in industry is to pass within the set period, the circuit connected several cycles, and then disconnect several frequency, change the thyristor in the set period of on-off time ratio, to adjust the average voltage or load power load on both ends of the communication, which is called the dynamometer or frequency controller; The dynamometer is the conduction of the thyristor when the power voltage is over zero, so the load is full of the sine wave, and the regulating is only the voltage cycle o