Conductive liquid property measurement using variable phase mixing
First Claim
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 toreceive 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.
1 Assignment
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Accused Products
Abstract
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.
29 Citations
20 Claims
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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:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of measuring an electrical characteristic of a fluid with a measuring circuit that includes a sensing node, a sensor switchably connected to the sensing node, and an array of components switchably connected to the sensing node, and a controller, the method comprising:
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mixing a signal indicative of a voltage at the sensing node at a first configuration of the array of components with a first phase signal and a second phase signal to create a first set of reference signals; mixing the signal at a second configuration of the array of components with the first phase signal and the second phase signal to create a second set of reference signals; adjusting the first phase signal and the second phase signal until a relationship between the first set of reference signals and the second set of reference signals satisfies a condition; setting a plurality of configurations of the array of components; mixing the signal with the adjusted first phase signal and the adjusted second phase signal at each of the plurality of configurations of the array of components to create a plurality of sets of reference signals; mixing the signal with the adjusted first phase signal and the adjusted second phase signal with the sensor connected to the sensing node to create a set of measurement voltages; determining the electrical characteristic of the fluid based on a relationship between the plurality of sets of reference signals and the set of measurement voltages. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. A system for measuring an electrical characteristic of a fluid, the system comprising:
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a sensing node; a sensor connected, via a switching array, to the sensing node; an array of components connected, via the switching array, to the sensing node, the array of components including a plurality of impedances; a monitoring circuit connected to the sensing node, the monitoring circuit configured to input a plurality of signals at a plurality of phases and output a signal related to a measurement signal at the sensing node; and a controller connected to the switching array and the monitoring circuit, the controller configured to receive the plurality of signals, set a first phase and a second phase of an input signal to the monitoring circuit; measure, at a first calibration impedance of the plurality of impedances, a first calibration voltage at the first phase and a second calibration voltage at the second phase; measure, at a second calibration impedance of the plurality of impedances, a third calibration voltage at the first phase and a fourth calibration voltage at the second phase; adjust the first phase and the second phase until a relationship between the first calibration voltage, the second calibration voltage, the third calibration voltage, and the fourth calibration voltage satisfies a condition; adjust the plurality of impedances by controlling the switching array to connect at least one component of the array of components to the sensing node in a parallel-type connection, determine a first set of reference signals based on the signal when the switching array is configured to couple a first measuring impedance of the plurality of impedances to the sensing node; determine a second set of reference signals based on the signal when the switching array is configured to couple a second measuring impedance of the plurality of impedances to the sensing node; determine a set of sensor voltages based on the signal when the switching array is configured to couple the sensor to the sensing node, and determine an electrical characteristic of the sensor based on the first set of reference signals, the second set of reference signals, and the set of sensor voltages.
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Specification