Capacitive Sensor Control Electrode for Multiphase Height Detection
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Solution Overview
Problem
Capacitive measurement devices in multiphase media face limitations in sensitivity and precision due to specific geometric arrangements of excitation electrodes, particularly when the spacing between electrodes is less than twice the thickness of dielectric walls, leading to reduced mutual capacitance dependence on fluid height.
Innovation Solution
Incorporation of a control electrode and a switching circuit that applies a common electric potential to the control electrode when connected to the ground plane and leaves it floating when disconnected, allowing for the measurement of mutual capacitance in both states to detect conductive phases and determine phase height without geometric constraints on electrode spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the spacing between excitation electrodes is reduced to less than twice the thickness of dielectric walls, then the device complexity is reduced and installation is easier, but the measurement precision and sensitivity deteriorate due to decreased mutual capacitance dependence on fluid height
Solution Approach 1:
A control electrode is introduced as an intermediary element between the excitation electrodes and the ground plane. This control electrode, when connected to ground, serves as a reference that enhances the sensitivity of mutual capacitance measurements to fluid height changes, allowing precise measurements even with reduced electrode spacing.
Solution Approach 2:
The invention changes the electrical parameter configuration by introducing a controllable ground connection at the control electrode. By switching the control electrode between grounded and floating states, the system modulates the electrical field distribution to maximize sensitivity to dielectric changes in the fluid, thereby improving measurement precision without requiring specific electrode spacing.
2Device complexity
If the spacing between excitation electrodes is reduced, then the device structure is simplified, but the reliability of detection deteriorates due to loss of sensitivity in detecting conductive phases
Solution Approach 1:
The control electrode acts as a mediator that, when grounded, creates a reference potential that enhances the detection capability for conductive phases. The presence of a conductive phase alters the mutual capacitance between excitation electrodes more significantly when the control electrode is grounded, improving detection reliability.
Solution Approach 2:
The system dynamically switches the control electrode between grounded and floating states to optimize detection for different conditions. This dynamic configuration allows the system to maintain high reliability for detecting conductive phases regardless of the fixed electrode spacing, adapting the electrical field distribution to the measurement needs.
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 reliability and precision of detecting phase presence and determining phase height in multiphase media, overcoming the limitations of existing devices by providing differential capacitance measurements that are independent of electrode spacing, thus improving measurement accuracy.
Implementation Method 1
at least one pair of excitation electrodes, forming a capacitor, and intended to be inserted into the multiphase medium; an electronic circuit, arranged to electrically connect the pair of excitation electrodes to the ground plane, and configured to: apply an electrical potential to each excitation electrode at a working frequency, and measure a mutual capacitance between the pair of excitation electrodes
Implementation Method 2
detect the presence of an electrically conductive phase at the working frequency as soon as the mutual capacitance measured when the switch is in the open state is different from the mutual capacitance measured when the switch is in the closed state
Data Source
Figure 1~3
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Figure 7~8
AI summary
The invention relates to a device comprising at least one pair of excitation electrodes (1, 2) forming a capacitor, a floorplan (PM), and an electronic circuit (3), characterised in that it comprises at least one control electrode (4) arranged at a distance from the capacitor, and a switching circuit (5) comprising a switch (50) having an open state and a closed state, and designed so as to apply, to the control electrode (4), an electric potential common to the floorplan (PM) in the closed state, and to leave a floating electrical potential for the control electrode (4) in the open state; and in that the electronic circuit (3) is designed to measure the mutual capacitance between the pair of excitation electrodes (1, 2) when the switch (50) is in the open state and in the closed state.