Liquid dielectric constant measuring system self-adapting to scale and precision

Abstract

The invention relates to a liquid dielectric constant measuring system self-adapting to scale and precision. The dielectric constant measuring system comprises a to-be-measured capacitor detector (1), a single-chip microcomputer (2) and an LED display. The single-chip microcomputer controls a switch circuit in the to-be-measured capacitor detector, an estimated value of the to-be-measured capacitor is acquired through a capacitor initial check circuit, a commutating and voltage-stabilizing circuit, and a low precision analog-digital converter in the to-be-measured capacitor detector and a corresponding computational formula, the estimated value is used to control a phase-locked loop to output a sampling lock with appropriate precision, then the state of the switch circuit in the to-be-measured capacitor detector is changed, the charging impulse of the to-be-measured capacitor is acquired through an RC charging and discharging subcircuit and a comparator circuit, the sampling clock is used to sample to acquire the charging time, and calculation is conducted to acquire the precise value of the to-be-measured capacitor, and finally, the dielectric constant of a corresponding liquid is obtained through calculation according to the structure of a measured electrode and the measured capacitance value and is displayed in the LED display.

Description

technical field [0001] The invention relates to the field of integrated circuit and system design, in particular to a liquid dielectric constant measurement system with self-adaptive range and precision. Background technique [0002] An important parameter in the electrical properties of liquids is their dielectric constant ε. In order to detect the dielectric constant, the capacitance value of a capacitor completely filled with the same liquid medium is generally measured, and then the dielectric constant is obtained according to the calculation formula of the capacitor. This method can be used to distinguish liquids with different components, and to identify deteriorated and contaminated liquids such as industrial lubricants, edible oils, etc., and has been widely used in industrial lubricants online monitoring systems. [0003] In order to achieve high-precision measurement, the accuracy of the analog circuit system is limited, and the digital circuit part can sample and...

AI Technical Summary

Problems solved by technology

If the digital part of the system uses a fixed precision, that is, a sampling clock with a fixed frequency, the measurement accuracy is not high when the capacitance to be measured is small, and the measurement range may be exceeded when the capacitance to be measured is large

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