The Circulating Water Temperature Control System Based On Fuzzy PID

The paper comes from the development of ultra-precision temperature controlsystem which belongs to the “02” major lithography.Temperature is a major object in manufacture and life. With the development ifhigh-precision technology, high-precision and ultra-precision temperature control areused in the industrial production increasingly, and the prospects if temperature control isbecoming broader. Since the temperature detection of temperature control system lagsthe temperature regulation, it’s easy to lead to the excessive temperature regulation ofthe whole temperature control system, the temperature oscillation and the changes ofparameters in temperature controller. The random temperature changes andunpredictable parameters regulation increase the difficulty of high-precisiontemperature control directly.The article analyses the characteristics of high-precision temperature controlsystem and the domestic/foreign control method of high-precision temperature controlsystem. After that, in the light of the characteristics of semiconductor refrigeration,designs and develops a new type of temperature controller which has advantages suchas high temperature control precision, broad, fast response, long steady time and so on.This design of high-precision temperature control system has two notableadvantages, one is the combination of analog circuits and digital circuits. It adjusts thevoltage signal by current, realizes the cycle and pulse control of voltage signalaccording to different current signal, and thereby accomplishes the purpose ofcontrolling the output power. The other one is that the whole temperature controlsystem uses a combination of rough and fine adjusting control. Rough means thetemperature control system can heat up or cool down quickly, while the fine adjustmentmake the system reach the given temperature and be stable ultimately.The control system uses the PIC24HJ12GP201microprocessor in PIC24series ofMicrochip Technology Incorporated, designs the rational and effective peripheryauxiliary circuit. It accomplishes the reasonable switch between rough and fine tuningof semiconductor cooling module, collection and transformation of temperature signal, nonlinear correction, the program writing of RS232communication serial port, digitalPID control software and PLC. It realizes the data exchange between ultra-precisiontemperature control system and computer, accomplishes the real-time monitoring ofultra-precision temperature control system by computer.The article builds a complete temperature system, regulates the parameter controlprocess of fuzzy PID control by reading lots of related documents and experiments. Atthe same time, it adds the incremental PID control algorithm and integral separationalgorithm to the control process. By texts, it proves that the adjusted ultra-precisiontemperature control system can reach the given initial target temperature quickly, and atthis temperature stably for a long time. The experiments show that the ultra-precisiontemperature control system has the advantages such as high control precision, fastresponse speed, small temperature fluctuations and so on. The PID parameterself-tuning control algorithm can also improve the response curve of temperaturecontrol system commendably.