STUDY ON OPTIMUM PID CONTROLLER SETTINGS FOR TEMPERATURE CONTROL IN A GROWTH CABINET

Abstract

To obtain the criteria for the optimum setting of the PID controller of temperature, the effect of the setting combinations of proportional band (PB), reset time (TI) and rate time (TD) on the response characteristics in temperature control was analyzed by measuring the control area and the settling time in step response of air temperature in a growth cabinet (KG 208) . From the results, following points were made clear:1) The response characteristics were remarkably affected by PB setting; the PB was most responsible for the control area and the settling time.2) When PB was more than 50%, the control area and the settling time were very large, and in most cases, the temperatures were not settled during an hour.3) When PB was 3%, the cycling occurred in all cases, regardless of TI and TD settings.4) When PB was 10%, the control area and the settling time were very small. However, when TD was 2 min, the cycling occurred even when PB was 10%.5) Optimum setting was given when PB is 10%, TI=10-20 min and TD=0-0.5 min.