Fiber Optic Current Sensor Temperature Compensation
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Solution Overview
Problem
Conventional high current measurement devices, particularly optical interferometers, face inaccuracies due to temperature variations affecting the quarter wave plate and the Verdet constant of the sensing fiber, leading to errors in current measurement.
Innovation Solution
A fiber optic current sensor system with multiple temperature sensors mounted around the optical fiber and a compensation coil, using a computer to calculate and apply correction factors to the current measurement based on averaged temperature data, ensuring accurate scaling and reducing temperature-induced errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical interferometer is used to measure current, then measurement is performed without electrical contact, but measurement accuracy deteriorates due to temperature variations
Solution Approach 1:
The patent applies parameter changes by measuring temperature at multiple locations (quarter wave plate temperature and fiber temperature) and using these temperature parameters to calculate correction factors that compensate for temperature-induced changes in the Verdet constant and wave plate characteristics, thereby maintaining measurement accuracy under varying temperature conditions
Solution Approach 2:
The patent implements feedback by continuously monitoring temperature conditions and applying real-time correction factors to the current measurement based on the measured temperatures, creating a closed-loop system that automatically compensates for temperature effects
2Measurement precision
If single temperature sensor is used, then device complexity is reduced, but measurement precision deteriorates due to insufficient temperature data
Solution Approach 1:
The patent applies segmentation by dividing the temperature monitoring function into multiple independent temperature sensors positioned at different critical locations (quarter wave plate and optical fiber), allowing each sensor to independently measure local temperature conditions that affect different components of the optical system
Solution Approach 2:
The patent achieves universality by using a computer-based processing system that handles multiple temperature sensor inputs and performs both temperature compensation for the current measurement and averaging of temperature readings, making the system capable of multiple functions through a single integrated processing unit
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
The system achieves an accuracy of 0.1% in high current measurements, significantly improving upon the 0.2% accuracy of existing technologies, thereby enhancing process control, energy management, and decision-making processes.
Implementation Method 1
Optical devices can also be used to measure current. Such devices are interferometers that utilize the Faraday effect, in which there is an interaction between light and the magnetic field produced around the conductor, to measure current.
Implementation Method 2
The quarter wave plate defines the beginning of the sensing region, where the beams are polarized, and the end of the sensing region for the returning light.
Data Source
AI summary
A non-contact device for measuring current in a conductor. The device includes an interferometer with an optical fiber that extends around the conductor and through which light beams pass. The magnetic field around the conductor, caused by the current conducted through the conductor, causes a phase shift in the light beams, which is measured. The measured current is corrected as a function of the temperature of at least the fiber, and possibly also the temperature of the quarter wave plate and/or the compensation coil in the interferometer. Multiple sensors are evenly spaced and mounted to the fiber in the preferred embodiment, and the signals from the sensors are averaged. The average signal is used to correct the measured current.