Design of furnace temperature control system based on CPLD

Temperature is a very important parameter in commercial control system. The hardware structure of most of temperature control system is very complicated because of having many resolution elements. With the large scale using of large capacity CPLD device, the structure of temperature control system can be simplified by using CPLD. A temperature automatic control system that adopts 8051 single-chip computer is designed in this paper. The control part of this system adopts CPLD device MAX7128. The system hardware consists of temperature measurement part and power control part. Temperature measurement part makes up of signal conversion circuit, signal processing circuit and signal gathering circuit. At the same time, because furnace is a first order inertia process with pure delay, system controller adopts Dahlin algorithm in order to enhance the system dynamic performance. The using of large capacity and low cost CPLD device MAX7128 enhances system reliability. The simulation results show that this system has lower overshoot and settling time. It can satisfy the demand of real-time control. Moreover, only a little adjustment of signal processing circuit and control algorithm, this system can also control the temperature of other process.