The Design Of Heating/cooling Circulator's Electric Control System

This essay gives a detailed account of the design of the soft and hard wares of heating/cooling circulator's electric control system. It mainly includes the temperature control of const temperature box and the variable frequency control for single-phase motor. And that temperature control is the core of whole design. In temperature control, the temperature-collecting system is composed of AVR Megal28 SCM, platinum resistors PT100 and 16 bit A/D AD7705 so as to get such high-precision on the hard wares. Using the control algorithm with combining self-adjust fuzzy control with digital PID control, the temperature can be controlled within the range of 4～60 ℃ with a precision of ±0.1℃ and uninterrupted adjustability of temperature setting is realized. In order to enhance the precision, this design proposes that software should be employed to carry on adjustment of measured precision; And meanwhile it calls for the application of the photoelectric insulation, the over electric current protection and alarm so as to enhance the security performance of the system.Based on the practices in engineering, in this paper some key technological problems are deeply discussed in designing the whole structures and hardware and designing controlling algorithm for this system. First, considering the technological requirements of the system and based on the study and absorption of relative theories and technologies for the key problems, the whole structure of temperature control system and variable frequency control system is designed which is satisfied for the requirements of high reliability, practicality and convenience operations. In the process of making temperature control realized, calculating precision is improved by designing software and, designing hardware improves measuring and controlling precision of the system. This strategy is of excellent accuracy and strong robustness. The adjusting results prove that the requirement of technology of the system is satisfied in essence. Next, considering the complexity of the heating and cooling process of the system, such as the characteristics of the time change and delay, the controlling strategy has to be designed to self-optimization based on temperature control algorithm, and enhances the self-adaptation of system greatly.