CONDUCTIVE LIQUID PROPERTY MEASUREMENT USING VARIABLE PHASE MIXING

摘要

A system and method for measuring an electrical characteristic of a fluid using a measuring circuit. In one implementation, the measuring circuit includes a sensing component, a current supply connected to the sensing component, a sensor switchably connected to the sensing component, an array of components switchably connected to the sensing component, and a monitoring circuit connected to the sensing component. A controller performs a calibration of the measuring circuit by switching parallel impedances in and out of the circuit while measuring voltages across the sensing component. The voltages are measured at at least two different phase angles that are determined by the calibration. Once voltages at different impedances and different phases are determined, the controller calculates a value of the electrical characteristic of the fluid by interpolating between lines of fixed capacitance or resistance.

主权项

1. A system for measuring an electrical characteristic of a fluid by separating a first orthogonal component of a signal change of a measurement signal and a second orthogonal component of the signal change of the measurement signal, where the first orthogonal component is due to a change in resistance across a sensor and the second orthogonal component is due to a change in capacitance across the sensor, the system comprising:
an array of components including the sensor; a mixer that mixes the measurement signal with a first phase signal and a second phase signal, the mixer outputting a first mixed signal related to the first phase signal and a second mixed signal related to the second phase signal; and a controller that is configured to
receive a signal indicative of the first mixed signal and the second mixed signal;control the array of components to cause the signal change;adjust the first phase signal and the second phase signal such that when there is a change in the first orthogonal component, the first mixed signal is increased and the second mixed signal is reduced;control the array of components to cause additional signal changes;receive a plurality of mixed signals indicative of the additional signal changes at the first phase and the second phase;determine the electrical characteristic of the fluid based on the plurality of mixed signals.