Study On Control System For Alfalfa Solar Drying Based On Fuzzy Control

Vigorously develop the forage industry, able to solve the problem of shortage of protein feed in China. Alfalfa as the king of grass yield, good quality, due to its containing more colloidal substances and small amounts of carbohydrates, which is not easy silage, so its moisture content must be in a relatively short period of time reduced to safe water to alfalfa quality.Solar energy drying is a nonlinear, time-varying process, so it is difficult to establish a precise mathematical model. Both classical control theory and modern control theory, a common feature is the built in system model based on. By comparison, the fuzzy control algorithm in the application of solar drying control system, to become the best choice. Based on the analysis of drying process of each influence factor the change rule and correlation of executive element based on drying box, select the actual temperature and the set temperature deviation, deviation change rate as input variables, the motor speed variable as output variables. Will the temperature deviation, and deviation of the variation of the precise amount into the fuzzy input amount, the precise amount speed into fuzzy output, and by manual control strategy for rising fuzzy control rules, to work out the output control the fuzzy set, the solution to get output control precision of fuzzy, in the role of the controlled object.Hardware part of the pre-set oven temperature upper limit value of60℃, humidity lower limit value of14%RH. The oven temperature and humidity by the digital temperature and humidity sensor SHT10measured. LCD1602for real-time display of oven temperature and humidity. Temperature and humidity sensors to collect temperature, humidity signal, this temperature, humidity signal is sent to the microcontroller. The actual value of the oven chip with the set value, this comparison into the fuzzy controller, the algorithm processing were controlled through the drive circuit chip blower, exhaust fan, buzzer starts and stops, in order to achieve the drying automatic process control.Software includes a main part of the design, five sub-programs, the main subroutine subprogram fuzzy control, temperature and humidity measurement and calculation routines, display routines, subroutines keys, alarm subroutines. Finally, the simulation and choose MATLAB toolbox Simulink to this design system computer simulation and simulate the system output. The results show, the fuzzy controller has the advantages of fast response, stable for a long time, small overshoot, can realize the automatic control of the drying process.