Magnetic-Inductive Flowmeter Coil Control Under Temperature Drift
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Solution Overview
Problem
Magnetic-inductive flow measurement devices are susceptible to deviations in determining flow-rate-dependent variables due to temperature changes and magnetic interference fields, leading to inaccuracies of up to 20% when relying on fixed coil current target values.
Innovation Solution
The device employs a control circuit that applies time-varying operating signals to separate coils, with specific time intervals and voltages to minimize deviations from predefined control targets, adapting to coil aging and external interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed coil current target value is used to generate the magnetic field, then the control system is simple, but the measurement precision deteriorates due to temperature changes and magnetic interference fields causing deviations up to 20%
Solution Approach 1:
The patent implements a feedback control mechanism where the actual coil current is continuously measured and compared against a target current value. The controller adjusts the operating signal to the coil arrangement based on the deviation between actual and target current, ensuring that the magnetic field strength remains stable despite temperature changes and magnetic interference fields. This closed-loop feedback system eliminates the 20% measurement deviations caused by environmental disturbances.
2Reliability
If the coil current is increased to maintain magnetic field strength under interference, then the magnetic field robustness improves, but the energy consumption increases
Solution Approach 1:
The patent employs dynamic current control where the target current value is not fixed but adapts based on operating conditions. The controller dynamically adjusts the coil current within an allowable range to maintain sufficient magnetic field strength for accurate measurements while minimizing energy consumption. This dynamic approach allows the system to use higher currents only when necessary to overcome interference, rather than continuously operating at high power levels.
3Measurement precision
If separate control of multiple coils is implemented to compensate for aging and interference, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent implements a universal control approach where a single controller manages multiple coils through a standardized feedback mechanism. The same control algorithm and adjustment principles apply to each coil, allowing the system to handle coil aging and interference compensation using a unified methodology rather than requiring separate complex control systems for each coil. This multi-functional control strategy maintains measurement precision while limiting the increase in device complexity.
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
Enhances the robustness of the magnetic field, making the device more resistant to external interference fields and temperature changes, with improved sensitivity and extended settling time, while maintaining accuracy.
Implementation Method 1
A magnetic-inductive flow meter has a device for generating a magnetic field, which produces a magnetic field perpendicularly to the flow direction of the flowing medium. Single coils are typically used for this purpose.
Implementation Method 2
A measurement electrode pair attached to the lateral surface of the measuring tube taps an electrical measurement voltage or potential difference which is applied perpendicularly to the direction of flow and to the magnetic field and occurs when a conductive medium flows in the direction of flow when the magnetic field is applied. Since, according to Faraday's law of induction, the tapped measurement voltage depends on the velocity of the flowing medium
Data Source
AI summary
A magnetic-inductive flow measurement device includes: a device for generating a magnetic field, including a first coil and a second coil; a device for tapping a measurement voltage induced in a flowable medium; an operating circuit configured to apply a first operating signal to the first coil and separately a second operating signal to the second coil, wherein a first voltage over a first time subinterval is applied to the coils, and coil currents of different measurement intervals of the first operating signal are changeable variables; and a control circuit configured to control at least the first voltage of the first operating signal such that a deviation of a control function from a predefined control target value, which includes a variable proportional to a magnetic flux, is minimized.