Temperature Transmitter EMF Correction for Faster Accurate Sensing
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Solution Overview
Problem
In process control systems, measurement inaccuracies occur due to elevated resistance in sensor connections caused by fraying, corrosion, or loose connections, leading to induced voltages that affect temperature sensor accuracy, and existing methods to account for residual EMF voltage are time-consuming, impacting update rates.
Innovation Solution
A differential voltage measurement system where the preexisting voltage across a sensor is latched to a storage capacitor and subtracted from the differential voltage before conversion, reducing inaccuracies and improving measurement speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional software-based EMF measurement and subtraction is used, then measurement accuracy is improved, but update time is increased
Solution Approach 1:
The circuit performs preliminary action by capturing the EMF voltage across the sensor before the excitation current is applied. The storage capacitor stores this pre-existing voltage, and then the circuit subtracts this stored EMF value from the subsequent measurement, eliminating the need for time-consuming software-based EMF detection and subtraction operations.
2Measurement precision
If multiple voltage measurements are taken for EMF detection, then measurement accuracy is improved, but measurement time is increased
Solution Approach 1:
The patent replaces the software-based sequential measurement and calculation process with a hardware circuit solution. The circuit directly captures, stores, and subtracts EMF values using electronic components (storage capacitor, differential amplifier, switches) in parallel, eliminating the need for multiple sequential voltage measurements and software processing.
3Measurement precision
If software-based EMF compensation is implemented, then measurement accuracy is improved, but device complexity is increased
Solution Approach 1:
The patent replaces complex software-based EMF compensation algorithms with a dedicated hardware circuit. The circuit uses a storage capacitor to capture EMF values, differential amplifiers to process voltage differences, and switches to control measurement timing, thereby simplifying the overall system by moving the complexity from software to dedicated hardware.
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 enhances measurement accuracy by compensating for residual EMF voltages in real-time, improving the update rate of temperature transmitters and reducing the impact of connection issues on sensor readings.
Implementation Method 1
a preexisting voltage across a sensor is latched to a storage capacitor
Data Source
AI summary
A preexisting voltage across a sensor is latched to a storage capacitor prior to any excitation current being applied to the sensor. Once the excitation current is applied, the voltage on the storage capacitor is directly subtracted from a differential voltage across the sensor. The subtraction is done before a measurement is converted to a digital value and passed to a transmitter. The subtraction is performed in hardware, and a time required to sample and hold the preexisting voltage across the storage capacitor is within a settling time used for collecting any sensor measurements.