Research And Design Of Capacitive Liquid Level Sensor Based On CAV444

In this subject,a capacitive level measurement system based on Atmel AT89S51 single chip microcomputer is designed as the main controller.After analyzing the measurement principle of traditional non-conductive liquid capacitive liquid level sensor,a kind of capacitance based on CAV444 capacitor-Voltage conversion chip level measurement method was adopted,a new error compensation scheme was proposed for the temperature drift in the system,and the circuit was designed to verify the correctness of this scheme.This paper mainly introduces the system design of the capacitive level sensor and the related hardware circuit module.The main modules of the hardware are power module,signal generation and conversion module,single chip and peripheral circuit module and digital voltmeter display module.And the detailed analysis of the principle and function of the discrete modules and interaction,and then also introduced the digital voltmeter display module programming.Finally,the compensation scheme of the capacitive liquid level sensor is designed and the data of the experimental measurement are analyzed.Through experimental tests prove that the measurement system was reliable and stable,the response was more sensitive,the maximum nonlinearity errorat room temperaturewas 1.10%,the measurement linearity was good;Under10-50 ? after error compensation,the reference errorwas 1.04%,the measurement accuracy was high.The compensation scheme provides an important reference for enterprises in the design and manufacture of related products.The temperature drift phenomenon in the market application of the capacitor level gauge has been improved,which has a certain significance.The measurement system can satisfy the demand for most industrial field level measurements.