Research Of Electronic Temperature Controlling And Dehumidifying In Small Environment

Temperature and humidity are two important parameters in effect of instrumentalstability, precision and life. Many devices and theirs parts have to certain the rangeof local ambient temperature and humidity, especially for the instruments whichcontain heat source themselves, and which are sensitive to the temperature andhumidity. And as development of instrumental miniaturization, light-duty, the spaceoccupied by instrument becomes smaller and smaller. So investigation oftemperature controlling and dehumidifying in small environment is verysignificant.Liquid cooling in temperature controlling and freezing method in dehumidifying intradition exist complex structure and high cost. And considering the characteristicsof nonlinear, time delay, time-variables and strong coupling, it is more complex tocontrol temperature and humidity. The paper controls temperature and dehumidifiesin small environment by semiconductor cooling technology, and automatic controland intelligent control is realized by using fuzzy control technology and PWMdriver. The paper mainly research and content are:1. Research of electronic temperature controlling and dehumidifying. Based on thesemiconductor cooling technology, the three implementing agencies of thesystem is designed, respectively for the semiconductor cooling system, semico-nductor heating systems and circulation fans. And considering the characteristics ofcontrolling temperature and humidity, the fuzzy control technology is provided,including fuzzy control structure, fuzzification, fuzzy reasoning andanti-fuzzy.2. Design of the simulation test box. The simulation test box mainly includes thebox, insulating layer, semiconductor cooling system and heating system. Thesemiconductor cooling system and heating system are designed especially,including selection of thermoelectric cooling, the choice of the ways of cooling andfixing etc. Two layers of four room structure is used in the box for temperaturecontrolling and dehumidifying, including temperature control room, condensationdehumidification room, circulation and heating room. The material of the insulatinglayer is chose, and the thickness of it are calculated and checked.3. Design of measurement and control circuit and design of software. The measurement and control circuit mainly includes the temperature and humiditymeasurement module, semiconductor chilling plate and fans driver module and thelord control and peripheral circuit module. The semiconductor chilling plate drivermodule is particularly important to the system, designing the PWM drive circuit,the isolation circuit and filter circuit. The software includes temperature andhumidity measurement program, fuzzy control program and PC display program.4. System experimental tests and analysis. The experiments of the open-loop arecompleted for studying important factors of the voltage of semiconductor chillingplate and fans. On this basis, the fuzzy control process is further improved and theexperiments of closed-loop were done. The obtained results validated feasibility,effectiveness.