基于CAV444的电容式液位传感器设计与优化

摘要

The measurement principle of capacitive liquid level sensor was introduced at first .And then,that how to design and optimize such a sensor based on CAV444 was proposed.Finally,a liquid level sensor was fabricated and tested.According to the rang of capacitance ,which corresponds to the measured level , the output voltage of the conditioning circuit was converted to in-crease the sensitivity of the sensor ,and a low-pass digital filter was designed according to the bandwidth of the signal to improve the resistance of the sensor .Finally,the design and testing of the sensor system were completed .The testing results shovo that the max non-linearity error is 0.75%,maximum fiducial error is only 1.13%,and this sensor has good linearity ,high measurement accura-cy,and good stability .Therefore,this sensor meets the requirements of practical liquid level measurement .%文中介绍了电容式液位传感器的测量原理，提出了一种基于CAV444线性电容－电压转换芯片的电容式液位传感器设计与优化方案。该方案根据所测液位范围对应的电容值变化范围对调理电路的输出电压进行了变换，以提高传感器的灵敏度，并根据被测信号的带宽设计了低通数字滤波器，提高了传感器的抗干扰能力。测试结果表明，该传感器性能稳定，最大非线性误差为0.75％，测量结果线性度好；引用误差为1.13％，测量准确度高，能够满足大多数工业现场实际的液位测量需求。