电容式谷物水分传感器平面探头的研制

针对谷物水分传感器平行极板探头安装难度大、高水分测量精度低等问题，将平行极板探头结构改进成为平面极板探头结构，并且通过增加保护极板减小干扰和杂散电容的影响，提出影响传感器敏感性、精度的平面极板探头的几个参数，采用有限元分析方法较精确分析了探头的电场分布和电容。根据能量的分布得到谷物测量深度、平面极板探头电容值同其驱动极宽与两感应极板间距（极距）之比的关系，当二者之比等于0.9时即为平面极板探头的优化尺寸。试验结果表明，该传感器测量含水率的误差在±1.5%范围内，测量含水率范围可达到6%～36%，测量温度范围-10～80℃。优化的平面极板探头提高了测量精度，降低了安装难度。

Development of plane polar probe of capacitive grain moisture sensor

Aimed to the problems of difficult installation and low measurement accuracy in high moisture,the grain moisture sensor has improved from the traditional parallel polar plate probe to plane polar plate probe.The plane polar probe with protect pole was used to decrease the affect of the stray capacitance and interference,and some critical parameters of the plane polar probe that influenced sensitivity and accuracy of the sensor were proposed.The finite element method was used to analyze the electric field an...