摘要:随着科技的发展，传感器的应用越来越普及。电容式传感器是将非电量的变化转换为电容量的变化来实现对物理量的测量。现已被广泛用于位移、振动、角度、加速度、压力、差压、液面、水分含量等方面的测量。

　　电容式传感器具有耗散功率小，输出阻抗低，静电引力小，动态性能好，灵敏度高，可实现非接触测量，对高温、辐射、强振等恶劣条件适应性强等优点。但由于寄生电容等、电容检测电路输出信号与电容大小呈现非线性等影响，使得电容式传感器的分辨率和测量范围受到很大的限制。

　　本文主要研究电容传感器虚部法测量电路。通过跟传统检测电路相比，虚部法检测电路可以改善电容式位移传感器检测电路的非线性，克服寄生电容的影响，增大电容式位移传感器的检测距离。利用Multisim 10进行仿真分析影响虚部法电容检测电路正比输出的原因。

关键词：电容传感器，虚部法，测量电路

Abstract：With the development of science and technology, sensor applications are becoming increasingly popular. Capacitive sensors are changes in non-electricity which converted to capacitance changes to the measurement of physical quantities. It is now widely used for displacement, vibration, angle, acceleration, pressure, differential pressure, liquid level, moisture content measurement.

　　The capacitive sensor has a small power dissipation, low output impedance, electrostatic attraction, good dynamic performance, high sensitivity and can be achieved non-contact measurement, adaptable to heat, radiation, strong vibration and other adverse conditions. However, due to the influence of the parasitic capacitance, the capacitance detection circuit output signal and the capacitor size is nonlinear, resolution and measuring range of the capacitive sensor under great restrictions.

　　In this paper, research capacitance sensor virtual measurement circuit. Compared with the conventional detection circuit, the imaginary part method detection circuit can improve the nonlinear capacitive displacement sensor detection circuit and overcome the effects of the parasitic capacitance. What’s more, it also can increase the detection range of the capacitive displacement sensor. The simulation of Multisim 10 can analysis the imaginary part of capacitance detection circuit, which can find out the reasons for the proportional to the output.

Key words: Capacitive sensors, Virtual footwork, Measure circuit