Research On Fuzzy Decoupling Control System Of Wood Dehumidiflcation Drying

Drying equipment is a key part in wood drying process, and its performance greatlyaffects the drying quality. In the design of control system for drying equipment, reasonablecontrol strategies could maximize the performance of drying equipment, thus shortening thedrying time, reducing energy consumption, improving the drying quality and increasingeconomic efficiency of enterprises. So it would be practically significant to introduce theintelligent control algorithm into the design of the control system of dehumidification drying.Analyzed with the overall structure and working principle of dehumidification dryingequipment, in this study, a kind of intelligent control system was designed on the basis of fuzzydecoupling theory. The control system could dynamically adjust the run-time proportion ofdehumidifier according to the changes of temperature and relative humidity in the drying kiln,then calculate turn-on time and stop time of dehumidifier in one control cycle T, so as toexactly control the drying process to meet the wood drying schedule. Main results for thisstudy are as follows:(1) Based on the fuzzy decoupling theory, a multivariable fuzzy decoupling controller wasdesigned for the process control of dehumidification drying. During the design process, it wasdivided into two SISO systems: temperature--the run-time proportion of dehumidifier andrelative humidity--the run-time proportion of dehumidifier; then the fuzzy controllers for twoSISO systems were designed respectively, their fuzzy control rules were established afteranalyzing and summarizing the control experiences which was accumulated from the long-termuse process of dehumidification drying equipment in Beijing Kaiming fiddle CO., LTD. Next,fuzzy reasoning was calculated on the basis of the fuzzy control rules so as to get the fuzzycontrol query tables of two SISO systems respectively. In the end the control output of MISOsystem was gotten from the synthesis calculation conducted between the control outputs of twoSISO systems in accordance with “min” criterion. (2) The dehumidifier cannot frequently open and shut down, and it requires a certain timeinterval between the opening and closing. For these working characteristics, the concept ofcontrol cycle T was proposed. According to the different drying stage, it can be configured todifferent values to control dehumidifier. This method could not only ensure the precise controlof temperature and relative humidity in the drying kiln, but also reduce device wearing toprolong the life cycle of the device, and improve the drying quality to some extent.(3) Considering the functions of auxiliary electric heater at different stages ofdehumidification drying, different control ideas for drying preheating stage and drying stagewere put forward. It could accurately supply the required heat in the drying kiln withoutaffecting the heating capacity of dehumidifier itself.(4) The hardware platform of control system for dehumidification drying was built andcontrol software was designed. Control system chosen ATmega1280single chip asmicrocontroller and adopt DWIN intelligent touch screen as the man-machine interactive way.Then suitable temperature&relative humidity sensor and data storage chip were selected.Finally the corresponding control programs were established to realize the precise control andvisual operation of dehumidification drying.(5) The actual use of dehumidification drying equipment under instrument control andfuzzy decoupling control were analyzed and summarized respectively in Beijing Kaimingfiddle CO., LTD. The results indicated that compared with instrument control, the controlsystem designed in this study could shorten the drying time, from30daysto23days; reducethe energy consumption and the energy-saving ratio is17%on the premise of good dryingquality. At the same time, the running time of dehumidifier decreased by157hours, so thedevice wear was reduced to extend the life of equipment.The research used fuzzy decoupling theory in the process control of dehumidificationdrying for the first time. The corresponding control system was designed. It has been used inthe actual production for over two years and obtained a good application result. The qualifiedrate of wood after drying in the equipment is over95%. The study can provide a reference for the design and application of the same type of dehumidification drying equipment. It has agood application prospect.