Temperature Control System Of Thermal Cycle Based On PLC

In the actual temperature control, normally, traditional control has some disadvantages, such as nonlinearity、time-variance、hysteresis quality,which makes the system hard to meet the need, even lose control. To adopt PLC control base on the expert control is a effective way to work out these problems. In this article, we use both ES theory and PLC control technology to study the thermal cycle control system.We make expert control rules base on the study of PLC and expert control, and use control method of PLC and expert control rules to design thermal cycle system. The control can be divided into two parts, one is refrigeration, and another is heat. In the refrigeration, when the deviation is much big, we control the temperature by adding or reducing the number of compressor, while the deviation is small, we control temperature by controlling the frequency of frequency converter, and so does fine adjustment. In the heat. we use the PWM to control the on-off time of SSR. which control the temperature through control the heat time of the heater. Besides, the article analyze in detail the system constructions and hardware.