摘要
提出利用介电损失角测量谷物含水率的方法,设计了一种新型电容传感器和由激励电路、选频放大器、相敏检波电路、低通滤波电路等组成的检测系统。通过对京411小麦的试验,建立了谷物含水率与介电损失角正切值之间的分段线性关系。多次标定试验表明,系统重复性误差小于0.5%。针对烘干机的大滞后、变参效等特点,采用前馈加反馈的智能 PI 控制器控制出粮含水率的在线测量和调节。
A method for measuring the grain moisture content by means of dielec- tric loss angle is presented.A measuring system consists of capacitance sensor, measuring circuit,signal acquisition and processing system is developed.Through experimental study on Jing 411 wheat,a sectionally linear relationship between the grain moisture content and the tangent of dielectric loss angle is derived.The re- suits of many rating experiments show that the repeat measuring errors of grain moisture content is no more than 0.5%.In view of drying time heavy laging and parameters varing,an intellectual PI controller with feedforward and feedback is used to control the on-line measuring and adjustment of final grain moisture con- tent.
关键词
谷物含水率
介电损失角
控制
谷物
烘干机
grain moisture content
dielectric loss angler intellectual PI controller
