【摘要】 杀青是茶叶加工过程的第一道关键工序,其中杀青过程中温湿度的精确控制是保证茶叶品质的关键。为提高茶叶品质,保证茶叶杀青充分,又不产生大量枯叶,基于STM32单片机,采用模糊PID和PWM温湿度闭环控制系统,输入量为实际温湿度与上限值的偏差值,用输出量PWM值控制风扇转速及红外加热管功率,达到精确控制滚筒杀青所规定的温湿度,并由Matlab进行仿真验证。结果表明,采用模糊PID和PWM温湿度闭环控制系统能精确控制滚筒内的温湿度值,温度误差控制在2℃以内,湿度误差控制在3%RH以内,可防止杀青叶因温度降低过慢而被烧焦,滚筒内湿度过高被闷黄等现象,满足茶叶杀青工艺要求,从而保证茶叶品质。更多还原

【Abstract】 Water-removing is the first important step of tea processing. As a key process, the accurate control of temperature and humidity is directly related to the quality of tea. In order to improve tea quality and ensure that the fresh tea leaves are fully water-removed without a large amount of bad leaves,a temperature-humidity closed-loop control system combining fuzzy PID and PWM is used to control the rotate speed of fan and the power of infrared heating tube on the basis of STM32 SCM,so as to achieve accurate control of the temperature-humidity values in the roller of water-removing machine. The deviation between the actual temperature/humidity and the upper limit is taken as the input,and the PWM value is taken as output. The simulation verification of the system is carried out with Matlab. The results show the fuzzy PID and PWM closed-loop control system can accurately control the temperature and humidity in the roller;the temperature error is kept within 2 ℃ while the humidity error is within 3%RH. It also can prevent the phenomenon that tea leaves are burnt due to the slow fall of temperature or become sallow because of too high humidity in the roller. Therefore,it can meet the requirements of tea waterremoving process and ensure the quality of tea.更多还原