Electrode Impedance Measurement in Electromagnetic Flowmeters
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Solution Overview
Problem
Electromagnetic flowmeters face inefficiencies in measuring electrode impedance without interfering with fluid flow measurements, leading to power consumption issues and potential measurement inaccuracies.
Innovation Solution
The method involves intermittently injecting an impedance measurement signal during the coil excitation drive signal, allowing concurrent measurement of electrode impedance and flow velocity without interleaving, using a comb filter to cancel out unwanted signals and extract impedance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrode impedance measurement is performed by injecting measurement signal, then electrode integrity verification is enabled, but flow measurement signal is interfered with
Solution Approach 1:
The patent applies periodic action by using intermittent injection of impedance measurement signals at specific time intervals within the excitation cycle, rather than continuous injection. This allows the system to measure electrode impedance periodically while maintaining flow measurement capability during other periods, thus resolving the contradiction between electrode verification and flow measurement accuracy.
Solution Approach 2:
The patent segments the measurement cycle into distinct time intervals: periods when impedance measurement signals are injected and periods when they are not. This segmentation allows separate optimization of impedance measurement and flow measurement, enabling both functions to perform accurately without mutual interference.
2Measurement precision
If flow velocity measurement is disabled during impedance measurement, then measurement interference is minimized, but measurement continuity is lost
Solution Approach 1:
The system uses periodic action to alternately perform impedance measurements and flow velocity measurements within the same operational cycle. The impedance measurement signals are injected intermittently at predetermined time intervals, allowing both measurements to occur continuously over time without permanent disabling of either function.
Solution Approach 2:
The patent maintains continuity of useful action by ensuring that both impedance measurement and flow velocity measurement occur continuously over time through intermittent but regular measurement cycles. This prevents gaps in monitoring capability while managing signal interference through timing.
3Use of energy by moving object
If measurement reading frequency is reduced to save power, then battery life is extended, but measurement resolution is degraded
Solution Approach 1:
The patent implements periodic action by performing both impedance measurements and flow velocity measurements at regular intervals within continuous operation. This intermittent but continuous approach reduces average power consumption compared to continuous high-frequency sampling, while maintaining adequate measurement resolution through optimized sampling intervals.
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 enables efficient, simultaneous measurement of electrode impedance and flow velocity, reducing power consumption and preventing measurement inaccuracies, while allowing for in situ verification of electrode integrity and fluid presence detection.
Implementation Method 1
an electromagnetic (EM) flowmeter relies on at least two measuring electrodes in order to measure the fluid velocity within a conduit
Implementation Method 2
measuring the impedance of the electrode to the measuring fluid, the measured impedance having a real component and an imaginary component
Data Source
AI summary
A method measures electrical impedance of electromagnetic flowmeter sensing electrodes includes intermittently injecting an impedance measurement signal to at least one sensing electrode while a coil excitation drive signal is applied to flowmeter field generating coils. During a first interval, when the coil excitation drive signal is applied to the coils and the impedance measurement signal is injected to a sensing electrode, a first measurement signal is obtained. The first measurement signal includes an electromagnetically induced flow measurement signal and an electrode impedance measurement signal. During a second interval, when the coil excitation drive signal is applied to the coils but the impedance measurement signal is not injected to the sensing electrodes, a second measurement signal is obtained that includes an electromagnetically induced flow measurement signal. The first and second measurement signals combine into an output signal including the electrode impedance measurement signal without the electromagnetically induced flow measurement signal.