Design Optimization Control of Blower in Coffee Roasting Process with Fuzzy Logic Controller

Coffee is a key commodity in Indonesia's plantation sector, where the quality of coffee flavor is influenced by the beans (60%) and the roasting process (30%) [1]. To improve the quality, a coffee roaster with controlled temperature and stable process is used. It has a closed combustion system with a 25 cm diameter tube and a capacity of 500 grams of green beans. Temperature stability is maintained by controlling the speed of the heat dissipation blower and the gas path through an automatic valve based on a threshold value [2]. The system uses K-type thermocouple sensors to detect temperature, with inputs in the form of error and integral error. Fuzzy logic control regulates the speed of the adaptive blower motor based on temperature changes. The sensor output generates an 8-bit PWM value through a zero crossing detector to adjust the speed of the AC blower motor. For example, at a temperature error of -10 and integral error of -1000, the system generates a value of 817.6 which is converted to 67% to adjust the blower motor speed. The gas valve is set with a threshold value of ±1℃. The results show that the system is more efficient with a reduction in excess oscillation.