Design And Implementation Of Dryer Temperature Control System Based On Fuzzy PID

The grain drying is a necessary step of grain transport and storage, grain dryer should have the ability of good efficiency and stability, temperature control of grain dryer is the key technology, high temperature will cause the gelatinization of grain, low temperature will not reach the effect of grain drying. Grain will be local heating because of uneven moisture after the storage, leading to mildew and rot. The structure of grain dryer is relatively simple, but the grain dryer temperature control system is a nonlinear, time-varying and large time delay control system, it is difficult to establish a precise mathematical model, the effect of conventional PID control is not very good.By consulting and studying a large number of literatures and information related to topic, taking grain dryer temperature control system of Jinzhou port limited by share food transportation center dryer renovation project as the foundation, the paper applied PID control algorithm and fuzzy control technology in grain dryer temperature control system and carried out the research on the design of fuzzy PID controller.For the hardware selection, Delta DVP14SS211 R type of PLC was selected as the core of the control system, delta DOP-B07S410 type of touch screen was selected as human-machine interface, Delta VFD075CP43A-21 type of frequency converter was selected, DVP-04 TC type of thermocouple module was selected as the temperature measurement module, K type thermocouple was selected as the temperature sensor.For the control method, touch panel was used to realize parameter setting and system state monitoring; PLC was used for receiving parameters set by touch screen and real-time temperature collected by temperature sensors, PID control algorithm was used to send instructions to frequency converter; frequency converter received the instruction of PLC, then controlled the speed of combustion air fan, thus the oxygen of dryer hot air furnace were changed, in order to achieve the purpose of indirectly controlling the degree of combustion of the combustion oven; temperature sensor real-time collected the temperature, then fed back to PLC through the process of temperature module, forming a closed loop system for dryer temperature control.Finally, MATLAB software and its SIMULINK software package were used to carry on the simulation, simulation results show that, the fuzzy PID controller designed in the paper improved the control precision of system, accelerated the dynamic response speed, enhanced the stability of system, reduced the overshoot of system. The controller has been applied in the actual production, and achieved good control effect.