Magnetic-Inductive Flowmeter Coupling Device for Feedback Reduction
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Solution Overview
Problem
Magnetic-inductive flowmeters face a feedback effect between impedance and flow rate determinations, which compromises the accuracy of flow rate measurement.
Innovation Solution
The flowmeter incorporates a coupling device with additional capacitors and switches that alternate between different capacitors during positive and negative magnetic field phases, reducing feedback and maintaining accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the coupling device uses only two capacitors (first and second capacitors) for galvanic isolation during positive and negative magnetic field phases, then the device structure remains simple, but a feedback effect occurs between impedance and flow rate determinations that compromises flow rate measurement accuracy
Solution Approach 1:
The coupling device is segmented into four separate capacitors (first, second, third, and fourth capacitors) arranged in a bridge configuration. This segmentation allows independent optimization of each capacitor's function: the first and second capacitors handle the positive magnetic field phase, while the third and fourth capacitors handle the negative magnetic field phase. This segmentation eliminates the feedback effect between impedance and flow rate measurements while maintaining structural organization through the systematic arrangement of the divided components.
2Ease of operation
If excitation signals are transmitted through the same capacitors used for flow measurement during both positive and negative magnetic field phases, then the device operation is simplified, but the feedback effect between impedance and flow rate determinations cannot be eliminated
Solution Approach 1:
The coupling device dynamically switches between different capacitor configurations based on the magnetic field phase. During the positive magnetic field phase, the first and second capacitors are activated for signal transmission and flow measurement. During the negative magnetic field phase, the third and fourth capacitors are activated. This dynamic switching, controlled by phase-synchronized switches, ensures that excitation signals for impedance measurement and flow measurement signals are transmitted through different capacitor paths, thereby eliminating the feedback effect while maintaining operational simplicity through automated phase-based control.
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 solution effectively reduces the feedback effect, allowing for accurate determination of both flow rate and impedance without compromising either measurement.
Implementation Method 1
a magnetic field generator (5) which generates an alternating magnetic field (21) with a positive magnetic field phase (22) and a negative magnetic field phase (23) in the medium (9) in the measuring tube (2)
Implementation Method 2
The first capacitor (10) is located in the first signal path (16), and the second capacitor (11) is located in the second signal path (17). The first and second capacitors (10, 11) galvanically isolate the impedance signal generator (6) and the first and second electrodes (3, 4) from one another, while also ensuring the transmission of the excitation signals generated by the impedance signal generator (6) to the first and second electrodes (3, 4)
Data Source
Figure 1
Figure 2a~2c
AI summary
A magnetic-inductive flowmeter (1) is shown and described, comprising a measuring tube (2), a first electrode (3), a second electrode (4), a magnetic field generator (5), an impedance signal generator (6), a coupling device (7), and a control device (8). The first electrode (3) and the second electrode (4) are connected to the measuring tube (2) for direct contact with a medium (9) within the measuring tube (2). The magnetic field generator (5) is designed to generate an alternating magnetic field (21) with a positive magnetic field phase (22) and a negative magnetic field phase (23) in the medium (9) within the measuring tube (2). The impedance signal generator (6) is designed to generate excitation signals (i). The coupling device (7) comprises a first capacitor (10), a second capacitor (12),The control unit (8) comprises a first signal path (16) and a second signal path (17). The first signal path (16) connects the impedance signal generator (6) and the first electrode (3), and the second signal path (17) connects the impedance signal generator (6) and the second electrode (4) for transmitting the excitation signals (i). The control unit (8) is configured to determine the flow rate of a medium (9) through the measuring tube (2) using flow measurement signals induced in the medium (9) by the alternating magnetic field (21) and measurable at the first electrode (3) and the second electrode (4). The control unit (8) is also configured to determine the impedance of the medium (9) in the measuring tube (2) using impedance measurement signals caused by the excitation signals (i) and measurable at the first electrode (3) and the second electrode (4). The invention reduces the feedback effect from the determination of the impedance of the medium on the determination of the flow rate of the medium by...that the coupling device (7) comprises a third capacitor (12), a fourth capacitor (13), a first switch (14) and a second switch (15), that the first switch (14), the first capacitor (10) and the third capacitor (12) are connected to each other and the first switch (14) is configured such that in a first switching state (S1) only the first capacitor (10) and in a second switching state (S2) only the third capacitor (12) is connected to the first signal path (16), that the second switch (15), the second capacitor (11) and the fourth capacitor (13) are connected to each other and the second switch (15) is configured such that in a first switching state (S1) only the second capacitor (11) and in a second switching state (S2) only the fourth capacitor (13) is connected to the second signal path (17), and that the control device (8) is configuredto set the first switch (14) and the second switch (15) to the first switching state (S1) for a duration of the positive magnetic field phase (22) and to the second switching state (S2) for a duration of the negative magnetic field phase (23).