Cold Junction Temperature Compensation Algorithm
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Solution Overview
Problem
Existing control systems using thermocouples and resistance temperature detectors face inaccuracies in temperature measurements due to environmental temperature disturbances, which current methods like physical insulation are expensive and not fully robust.
Innovation Solution
A method and system that calculates the cold junction temperature using an algorithm developed in an offline phase, deployed in firmware, which utilizes current and historical temperature readings to estimate the cold junction temperature without requiring physical closure, thereby compensating for environmental disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical insulation (environmental closure) is added to mitigate temperature disturbance, then temperature measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical/physical insulation system with a computational algorithm. Instead of using physical closure to isolate the cold junction from environmental temperature disturbances, the system uses an algorithm that processes temperature readings from accessible sensors to calculate compensated temperature values, thereby eliminating the need for complex physical insulation structures.
Solution Approach 2:
The patent introduces an algorithm as an intermediary computational layer between the temperature sensors and the control system. This algorithm acts as a mediator that processes raw temperature readings, applies compensation calculations based on thermal models, and produces accurate temperature measurements without requiring direct physical protection of the cold junction.
2Reliability
If physical insulation is used to protect cold junction, then reliability against environmental disturbance is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent substitutes complex mechanical insulation structures with a software-based algorithm deployed in firmware. This replacement maintains reliability against environmental disturbances while dramatically simplifying manufacturing, as firmware can be updated without physical rework and requires no additional insulation materials or assembly steps.
Solution Approach 2:
The patent changes the approach from modifying physical parameters (adding insulation material, changing structural properties) to modifying computational parameters (algorithm coefficients, thermal model parameters). This allows the system to adapt to different environmental conditions through software configuration rather than physical redesign, improving ease of manufacture.
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 provides accurate temperature measurements by minimizing the difference between calculated and actual cold junction temperatures, enhancing the robustness and cost-effectiveness of temperature compensation in control systems.
Implementation Method 1
The temperature detected by the sensor on the PCB is often regarded as the cold junction temperature. However, abrupt environmental temperature disturbances (i.e. wind, exposure to heated wires or other PCB elements, exposure to the environment outside the control system cabinet, etc.), cause a difference between the on PCB sensor detected temperature and the temperature of the screw actually causing electric potential difference. This is a result of the varying thermodynamic properties of such elements (i.e. thermo capacity, thermo conductivity, etc.).
Data Source
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AI summary
A method and system for calculating a cold junction temperature comprises an offline phase comprising: determining an applicable algorithm for calculating a cold junction screw temperature, and deploying the applicable algorithm in firmware; and an online phase comprising: providing at least one measured temperature to the applicable algorithm deployed in firmware, calculating a temperature of a cold junction screw according to the applicable algorithm deployed in firmware, and assigning the calculated temperature of the cold junction screw as a cold junction temperature.