Magneto-Inductive Flowmeter Feedback Control for Stable Field Energy

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Solution Overview

Problem

Magnetic-inductive flowmeters are susceptible to deviations in flow velocity measurements due to temperature changes and magnetic interference fields, leading to inaccuracies of up to 20% without effective control methods.

Innovation Solution

A magnetic-inductive flow measuring device with a control circuit that regulates operating signal parameters, such as coil current and voltage, to maintain a controlled variable proportional to magnetic field energy, reducing sensitivity to interference and temperature effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If coil current is controlled to a fixed setpoint, then the control system is simple and does not require measuring magnetic induction, but the magnetic induction cannot be reproduced due to temperature changes and magnetic interference fields, leading to measurement deviations of up to 20%

Engineering Contradiction:
Improvecontrol system complexityVSAvoidflow velocity measurement accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements a feedback control mechanism where the actual magnetic induction is continuously measured and compared to a reference value. The coil current is dynamically adjusted based on the deviation detected by the feedback signal, ensuring that the magnetic induction remains stable despite temperature changes and magnetic interference fields. This closed-loop control eliminates the measurement deviations of up to 20% that occur with fixed setpoint control.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If magnetic induction is continuously measured and controlled, then measurement accuracy is improved, but device complexity increases due to additional measuring and control circuits

Engineering Contradiction:
Improveflow velocity measurement accuracyVSAvoidcontrol system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent integrates magnetic induction measurement and feedback control circuits that continuously monitor and adjust the coil current to maintain stable magnetic induction. This feedback mechanism ensures high measurement accuracy by compensating for temperature changes and magnetic interference fields, while the integrated design minimizes the increase in device complexity.

Inventive Principle:
Principle #23Feedback

3Force

If coil current is increased to overcome magnetic interference fields, then magnetic field strength is improved, but temperature-dependent self-induction effects are amplified, increasing sensitivity to temperature changes

Engineering Contradiction:
Improvemagnetic field strengthVSAvoidtemperature sensitivity
Core Design Contradiction:
ForceVSObject-affected harmful factors

Solution Approach 1:

The patent uses feedback control to dynamically adjust the coil current based on the actual magnetic induction level. This ensures that the magnetic field strength is sufficient to overcome magnetic interference fields while avoiding excessive current that would amplify temperature-dependent self-induction effects. The feedback mechanism maintains optimal current levels, reducing sensitivity to temperature changes.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent dynamically changes the coil current parameter based on feedback signals that detect deviations in magnetic induction. By adjusting the current in response to actual conditions rather than using a fixed high current, the system maintains adequate magnetic field strength while minimizing temperature-dependent self-induction effects.

Inventive Principle:
Principle #35Parameter changes

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

The device achieves greater insensitivity to external interference fields and temperature-dependent self-induction, with faster settling times and improved accuracy in flow velocity measurements.

Implementation Method 1

The coil current flowing through the assembly generates a magnetic field with a magnetic induction that depends on the coil current

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

This voltage arises when a conductive medium flows in the direction of flow under an applied magnetic field. Since the detected measuring voltage depends on the velocity of the flowing medium according to Faraday's law of induction

Methodology Applied
Scientific EffectFaraday's law of induction: Electromagnetic Induction

Data Source

PatentEP4370876B1Magneto-inductive flow measurement device
Publication Date: 2025.11.26 ENDRESS HAUSER FLOWTEC AG
  • EP4370876B1 patent drawingFigure 1
  • EP4370876B1 patent drawingFigure 2~3
  • EP4370876B1 patent drawingFigure 4

AI summary

The invention relates to a magneto-inductive flow measurement device for determining a flow-rate-dependent measured variable for a flowable medium, comprising: a device (5) for producing a magnetic field, the device for producing the magnetic field comprising a coil arrangement (25); a device (8) for tapping off a measurement voltage induced in the flowable medium, in particular by means of two preferably diametrically arranged measurement electrodes (17, 18); an operating circuit (7) configured to apply an operating signal (11), in particular a voltage signal (12), to the coil arrangement (25), the operating signal (11) having operating signal parameters; and a controller circuit (10) configured to control at least one of the operating signal parameters in such a way that a controlled variable does not differ from a predefined setpoint value, the setpoint value comprising a magnetic field energy of proportional magnitude.