Inductive Conductivity Meter Impedance Matching

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Solution Overview

Problem

Inductive conductivity meters face inaccuracies in determining electrical conductivity due to varying amplitudes, leading to errors in measurement across the entire range of values.

Innovation Solution

The method involves specifying a setpoint input impedance, determining and adjusting the terminating impedance to match the input impedance, and iteratively adapting this process to compensate for changes in conductivity, allowing for accurate conductivity determination using the adjusted input and terminating impedances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the amplitude of the receiving alternating signal is measured to determine conductivity, then conductivity can be determined from the signal ratio, but the accuracy of determination is not constant over the entire range of values

Engineering Contradiction:

Improveconductivity determination accuracyVSAvoidmeasurement accuracy consistency

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The control device continuously monitors the actual input impedance and compares it with the setpoint input impedance. Based on this feedback, the control device automatically adjusts the terminating impedance to maintain optimal measurement conditions, ensuring constant accuracy across the entire conductivity range.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The invention dynamically changes the terminating impedance parameter based on the measured input impedance. By adjusting the terminating impedance in response to varying conductivity conditions, the system maintains constant measurement accuracy across different amplitude ranges.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If a fixed amplitude transmitting alternating signal is used, then the measurement process is simplified, but measurement errors occur across the entire range of conductivity values

Engineering Contradiction:

Improvemeasurement process simplicityVSAvoidconductivity determination accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system transitions from a static fixed amplitude signal to a dynamic adjustable amplitude signal. The control device varies the transmitting alternating signal amplitude based on the measured input impedance and setpoint comparison, optimizing measurement accuracy across different conductivity ranges while maintaining operational simplicity.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If the terminating impedance is fixed, then the device structure is simpler, but the input impedance varies with conductivity changes leading to measurement errors

Engineering Contradiction:

Improveterminating impedance adjustment mechanismVSAvoidconductivity determination accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The control device implements feedback by continuously measuring the input impedance, comparing it with the setpoint, and adjusting the terminating impedance accordingly. This feedback mechanism maintains measurement accuracy while providing a clear structure for the adjustment process.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The control device performs multiple functions: it measures the input impedance, compares it with the setpoint, determines the difference, and controls the terminating impedance adjustment. This multi-functionality reduces overall device complexity while maintaining high measurement precision.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances the accuracy of conductivity measurement by compensating for changes in input impedance, reducing measurement inaccuracies and maintaining a narrower range of amplitude values, thus improving the overall precision of conductivity determination.

Implementation Method 1

The inductive coupling of the transmitting coil and the receiving coil with one another by the electrically conductive medium takes place in that the transmitting alternating signal fed into the transmitting coil generates eddy currents in the medium and the eddy currents induce an electrical receiving alternating signal in the receiving coil

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10585055B2Method for operating an inductive conductivity meter and respective conductivity meter

Publication Date: 2020.03.10 KROHNE MESSTECHNICK GMBH & CO KG

AI summary

A method for operating an inductive conductivity meter having a transmitting coil, a receiving coil and a terminating impedance device, the transmitting coil having a transmitting coil terminal, the receiving coil having a receiving coil terminal and the terminating impedance device having a terminating impedance, wherein the receiving coil is terminated with the terminating impedance device and wherein the transmitting coil and the receiving coil are inductively coupled with one another by an electrically conductive medium. To provide an improved accuracy of a determination of a conductivity of a medium a setpoint input impedance is specified, an input impedance is determined at the transmitting coil terminal, the terminating impedance is set such that the input impedance is matched to the setpoint input impedance, and a conductivity of the medium is determined using the adjusted input impedance and the set termination impedance.