RTD Self-Heating Correction via Dual Sensing Elements
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Solution Overview
Problem
Resistance temperature detectors (RTDs) with dual sensing elements on a shared substrate face self-heating errors due to fault currents, leading to inaccurate temperature measurements, which can propagate and affect both channels, potentially causing engine performance degradation or stalling.
Innovation Solution
A method and system that measure the intensity of electric currents in one sensing element and apply corrections to the temperature measurement of the other element based on stored correction data, accounting for both current intensity and fluid mass flow rate, to mitigate self-heating errors and maintain accurate temperature readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fault current exceeding 5 mA passes through a sensing element, then the sensing element can withstand the fault without destruction, but self-heating errors cause temperature measurement accuracy to deteriorate
Solution Approach 1:
The patent segments the temperature measurement function into two independent sensing elements on the same substrate. When one element experiences fault current and self-heating, the other element remains unaffected and provides accurate temperature measurement. This segmentation isolates the harmful self-heating effect to one element while preserving measurement accuracy through the other element.
Solution Approach 2:
The patent uses the second sensing element as an intermediary to compensate for the self-heating error in the first sensing element. By measuring the temperature with the unaffected element and using it to correct the reading from the affected element, the system maintains measurement accuracy even when one element experiences fault conditions.
2Device complexity
If two sensing elements are positioned close together on the same substrate, then device complexity is reduced, but self-heating from one element propagates to the other via thermal conduction
Solution Approach 1:
The patent places two sensing elements on the same substrate but uses them in a segmented manner - one element is dedicated to measurement while the other serves as a reference or compensation element. This segmentation allows close positioning for structural simplicity while maintaining measurement accuracy through functional differentiation.
Solution Approach 2:
The patent implements a feedback mechanism where the temperature measurement from one sensing element is used to correct or compensate for self-heating effects in the other element. The system continuously monitors and adjusts based on the interaction between the two elements, maintaining accuracy despite thermal conduction.
3Measurement precision
If the feed current is kept low below 5 mA, then self-heating errors are limited, but the sensing element cannot withstand fault currents above 22 mA without destruction
Solution Approach 1:
The patent segments the current handling function between two sensing elements. One element operates at low current for accurate temperature measurement, while the other element can withstand fault currents. The system uses the low-current element for precision measurement and the other element as a protective backup that can handle surge currents without compromising the measurement accuracy of the primary element.
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 effectively compensates for self-heating errors caused by fault currents, ensuring reliable temperature measurements and preventing engine performance issues by accurately accounting for the impact of current intensity and fluid flow on temperature readings.
Implementation Method 1
The resistance of a sensing element 3, 4, in metal in particular and more particularly in platinum is dependent on the temperature of said sensing element 3, 4
Implementation Method 2
the feed current creates power dissipation via Joule effect generating self-heating of the sensing element 3, 4 inside which the current circulates
Implementation Method 3
the self-heating of one of the sensing elements 3, 4 is likely to propagate via thermal conduction to the other sensing element 3, 4
Data Source
AI summary
The invention relates to a temperature measurement method using a thermometric resistance-type temperature probe (1) comprising at least two electroconductive sensitive elements (3, 4) on the same substrate (2), wherein different parameters representative of the strength of the electric current circulating in one of said sensitive elements (3, 4) are measured, and a correction, according to said strength of the electric current circulating in said sensitive element (3, 4), is applied to a signal representative of a temperature measurement generated from the other one of said sensitive elements (3, 4), in order to correct an error created as a result of the self-heating by the Joule effect of said sensitive element (3, 4) affecting the other one of said sensitive elements (3, 4).