1、 外文翻译 译文： ： ： ； ； 1 Introduction Hot stove using simple bit type constant temperature control method, temperature control precision is not high, the temperature control is of unidirectional rising, large inertia, large time delay, time-varying characteristics, and the heating, thermal insulation is
2、dependent on the resistance wire heating, cooling, rely on the natural environment for cooling or add furnace material, once the overshoot is difficult to use control means to bring the temperature. According to mathematical model of controlled object is difficult to determine precisely the characte
3、ristics, the system consists of PLC as the core controller, according to the temperature change of the PID controller, the collection of temperature data, and then through the PLC output control, regulating thyristor conduction, to achieve accurate control of temperature. In this paper, the control
4、object is commonly used in the metallurgical industry in HX1 type electric heating furnace, furnace temperature for 20-600 2 System structure . The hardware device is mainly composed of PC, programmable controller, temperature sensor, temperature transmitter, solid state relays and electric heating
5、furnace. As shown in figure 1. Fig 1 the block diagram of the control system of heating furnace The control system of control information and data information in the computer centralized management, allocation, make the system more simple, effective, the user can browse, printing various field data,
6、 statements, and also to control the spot operation control. The temperature control system of single loop control system, by the Mitsubishi Co Fx2N series PLC as the core component, temperature detection using platinum thermal resistance KrlOO, used for real-time detection of temperature output, th
7、e RTD module is placed after the big into analog input module Fx2N 4AD, converted into digital quantity, the user procedure, call the PLC internal PID the control algorithm, a PID operational values, the values are converted into time value, to a time-varying PWM wave to control zero voltage trigger
8、 solid state relay SSR, to regulate the electric heating wire working current, to realize the heating furnace temperature control system. The software part Windows XP as the operating system, the industrial control configuration software MCGS as the application server platform. Between computer and
9、PLC through the MPI port connection, the realization of PC and PLC communication. By the computer to complete the temperature setting, temperature and various control parameters real-time monitoring. 3 PID control algorithm to achieve the PLC Using programmable controller for analog PID control, you
10、 can use the PID process control module, and this module is expensive, economy is poor. The system uses the PID function instruction, when P1D function instruction with the analog quantity when used together, not only can be similar to the PID process control module, and the economy is good. Due to
11、the heating furnace is large delay, large inertia link control object, the system adopts the integral separation PID algorithm and Bang position Bang control methods, namely at the beginning of the process, the Cambodian guitar or substantially increase the set value, by using the Bang Bang control,
12、 prevent excessive deviation, integral accumulation, the system caused by larger overshoot even oscillation, so that the system stability decline. And to the process of the late, when the deviation to the specified range, increase the integral action, in order to improve the control precision. In the actual process of debugging, after several revisions of control parameters, can achieve good control parameters, to achieve the required precision. PLC main program flow diagram as shown in figure 2, Fig 2 The PID algorithm program flow diagram as shown in Figure 3
