电容传感器的复数电压测量法

Complex Number Voltage Measuring Method of Capacitive Sensors

为解决批量生产的电容传感器检测效率低,无法满足生产需要的问题,提出了一种复数电压测量法。采用这种测量法可以同时对多个传感器的电容值和品质因数进行测量,并对模拟电路中的电子开关、运算放大器、正弦波发生电路进行跟踪鉴测,给出了修正的数学模型,并进行了数字修正。方法已在电容式湿度传感器性能测试仪中应用,对电容值在30～100pF范围的湿度传感器实现了0.1pF的高分辨率测量,误差达到±0.2pF,Q值测量误差达到±5％。

At present, the low efficiency measuring method of the capacitance sensors are widely used, but can't satisfy the need of the batching production. In order to solve the problem, a measuring method of complex number voltage is raised in this paper. The capacitance value and quality factor (Q) of multiple sensors can be measured at the same time by this measuring method. In this method, to the effect of electron switch, current amplifier and sine wave generator in analogue circuit, tracking detection is adopted, the mathematical model is established and digital redress is made. The method has been applied at the measuring instrument of capacitive humidity sensor. To the capacitance ranging from 30pF to 100pF, the measurement of high resolution that reaches 0.1 pF is realized. The accuracy of capacitance can reach +0.2pF and the one of Q can get up to +5%.