Capacitance Pressure Transducer Power Dissipation Control
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Solution Overview
Problem
Capacitance pressure transducers face challenges in maintaining constant power dissipation, especially in low range, high gain applications, due to temperature effects and transient shifts, which can lead to instability and thermal gradients.
Innovation Solution
A system that includes a shorted diaphragm level detector and a power dissipation circuit with a switch and resistor to maintain constant power dissipation by detecting diaphragm shorting and adjusting the oscillator's frequency and voltage, using a step-up transformer to optimize excitation and minimize power dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If thermal isolation between the sensor interface board and the sensor is added to maintain constant power dissipation, then power dissipation stability is improved, but temperature control of the electronics is compromised
Solution Approach 1:
A compensating circuit is introduced as an intermediary element between the power source and the sensor interface board. This circuit monitors the actual power dissipation and dynamically adjusts the power delivery to compensate for diaphragm shorting effects, thereby maintaining constant power dissipation without requiring thermal isolation that would compromise electronics temperature control.
2Stability of the object's composition
If attempts are made to eliminate temperature effects at zero pressure to maintain constant power dissipation, then power dissipation stability at zero pressure is improved, but other pressure points remain vulnerable to transient shifts
Solution Approach 1:
A feedback mechanism is implemented where the system continuously monitors the diaphragm position and capacitance changes across the full pressure range. When diaphragm shorting is detected at any pressure point, the compensating circuit dynamically adjusts the power delivery in real-time, ensuring constant power dissipation is maintained not only at zero pressure but across all operating pressure points, thereby improving overall transducer reliability.
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 maintains stable power dissipation across the sensor interface board, reduces thermal transient behavior, and improves signal-to-noise ratio by compensating for power reduction during diaphragm shorting, thereby enhancing the reliability and thermal control of the transducer.
Implementation Method 1
capacitance pressure transducer having a capacitance detecting circuit configured to detect a change in capacitance between a diaphragm and a reference electrode
Implementation Method 2
a switch configured to cause a current to be transmitted through a resistor, when the shorting of the diaphragm has been detected, thereby maintaining power dissipation in the transducer substantially constant when the diaphragm shorts
Data Source
AI summary
A system and method are described for maintaining power dissipation substantially constant across the sensor interface board of a capacitance pressure transducer. A shorted diaphragm level detector detects a shorting of the diaphragm onto one or more reference electrodes. A power dissipating resistor is placed near the oscillator that drives the capacitance detecting circuit in the capacitance pressure transducer. The resistor is switched across a power supply when the shorting is detected, causing current to flow through the resistor so that power can be added in an amount sufficient to maintain power dissipation by the oscillator substantially constant when the diaphragm shorts.