Analysis And Research Of High-Precision Temperature Control Instrumentation

With the development of modern production and scientific research, the processof temperature control have become increasingly demanding, and temperature controlinstrumentation for the measurement of the department requires a higher accuracy,stability and reliability.This paper describes the measurement of temperature control instrumentationand control methods, and combining of detailed system design specifications andrequirements on this basis, it is developed by Freescale microcontroller as the core oflow-cost, high-precision temperature control system.In hardware, use a high-performance 16-bit Freescale microcontroller(MC9S12XS128) as a control instrument of the core control device, and selectAD7714Y AD converter as a system converter,the actual voltage value is measured byAD7714Y, the filter effect well, the precision high, while using LCM12832ZK as aliquid crystal display device, it makes computer interaction more friendly.In software, using look-up table and linear interpolation algorithm in platinumresistance and temperature range gives the corresponding polynomial fittingformula ,to change the program code of computing the space for the speed andaccuracy.Temperature control use a fuzzy adaptive PID control algorithm.Amongthem, based on the proportion of calculus in the analysis of fuzzy control structure, itsimplifies fuzzy PID control structure, and writed a fuzzy PID algorithm in C andported to MC9S12XS128 chip program, the final run is to reach the precisemeasurement and control results.Temperature control instruments send data to a PC by RS232 bus, and PC canmake up for the next crew due to resource constraints because the chip can not keeplarge amounts of data deficiencies. PC software system can be achieved in addition tohistorical data stored function, it is also displayed real-time dynamic curve oftemperature variation.