电容传感器处理电路

为减少电容传感器处理电路带来的测量误差，提高仪器的测量精度和稳定性，利用对称平衡电路，选用“零”温漂系数的电容作为参考，用于补偿温度变化引起的电子元器件参数漂移带来的误差；采取“中和电流”的方式，消除本体电容、寄生电容对测量结果的影响，提高了传感器的测量分辨率，降低了处理电路对驱动电缆的要求．实验表明，用1．5m长的电容传感器测量油位，分辨率可达0．1mm，常温下长期稳定性小于0.3mm，与其他处理方式相比，精度从0．8％提高至0．18％．

Processing Circuit for Capacitance Sensor

To reduce the measurement error brought by the processing circuit and improve the measurement resolution of the capacitance sensor,a new processing circuit was presented.Considering the measurement precision and stability,a sym-metrical and balanceable circuit,which takes a capacitor of zero thermal coefficient for reference,was applied to compensate the drift error of components parameter.The neutralizing-current method can reduce the effect from the inherent capacitance and parasitic capacitance.As a result,the circuit improves the resolution of the measurement and reduces the demand for the drive-cable in the processing circuit.The experimental result shows that when the capacitance sensor with a length of 1.5 m measures the fuel level,0.1 mm resolution can be achieved,and the long-term stability is less than 0.3 mm.Compared with other measuring methods,the accuracy of the presented method can be increased from 0.8% to 0.18%.