Abstract: According to the characteristics of delay, inertia and nonlinearity in the baking of tea materials, the low accuracy of temperature control, large overshoot and poor robustness of traditional PID control largely limited relative application. A tea drying machine was designed based on DMC-PID control in this paper. The drying machine adopted multi-layer tunnel with the infrared radiation plate heating element above the conveyor belt. The DMC-PID cascade temperature control system was also used. The first DMC algorithm improved the robustness and capability of the dynamic temperature control system and the second PID algorithm improved the anti-jamming performance simultaneously. The green tea baking experiment on the prototype was carried out. The results showed that when the PID temperature control system was adopted, the overshoot of the dryer became 10.5%. When the DMC PID cascade temperature control was used,the overshoot was 5.9%. DMC-PID control could improve the temperature control precision and tea quality of the tea dryer.

Key words: tea dryer, DMC-PID control, infrared radiation heating unit