Abstract
A nonlinear hysteresis model of magneto-mechanical-thermo coupling for Terfenol-D materials is presented according to Wiss ferromagnetic theory, thermodynamics relations and Jiles–Atherton model. Numerical calculation and experimental results show that the mode well reflects the magnetostrictive characteristics of Terfenol-D rod under the coupling of stress, temperature and magnetic field. A fiber Bragg grating current transformer based on Terfenol-D material is designed according to the strain sensing mechanism of fiber Bragg grating and the demodulation principle of unbalanced M–Z interferometer. The theoretical analysis and research on the working characteristics of the fiber current transformer under the influence of different prestressing force and bias current are carried out. The results are important for the design and application of the current transformer with the Terfenol-D material.
Highlights
High accuracy, safety, stability and reliability of high voltage and high current detection have always been the key to the measurement of power system, and the current transformer with optical fiber as sensing element has become a research hotspot in the measurement of power system with its advantages of high stability, reliability, antielectromagnetic interference, corrosion resistance, integration of sensing and transmission, compatibility with digital communication system, etc.The optical current transformer based on the Faraday magneto-optical effect is studied in reference [1,2,3,4], which uses magneto-optical crystal/glass as a sensing element and optical fiber as the transmission link to realize 3000 A
The continuous curve was the numerical calculation result of the model, and the curve composed of discrete points was the actual test result. It can be seen from the figure that the calculation results of the dynamic hysteresis nonlinear model of the Terfenol-D material considering the multi field coupling characteristics were in good agreement with the measured results
The results show that the dynamic model could reflect the hysteresis and nonlinear characteristics of Terfenol-D
Summary
Safety, stability and reliability of high voltage and high current detection have always been the key to the measurement of power system, and the current transformer with optical fiber as sensing element has become a research hotspot in the measurement of power system with its advantages of high stability, reliability, antielectromagnetic interference, corrosion resistance, integration of sensing and transmission, compatibility with digital communication system, etc. The optical current transformer based on a magnetic fluid is a new type of current transformer, which has developed rapidly in recent years [12,13] This transformer uses the magnetic controllability of magnetic fluid and SMS (Single mode-Multimode-Single mode)optical fiber structure to realize the measurement of current or magnetic field. The characteristic fiber grating and giant magnetostrictive material (Terfenol-D) is an important direction of the of this type ofofsensor that it does not needinpolarization fiber and devices, is easy development opticaliscurrent transformer recent yearsmaintaining [20,21,22,23]. Demodulation technologies affect thechange measurement and accuracy based giant magnetostrictive can reflect thethat wavelength in real sensitivity time and accurately is one of on theakey technologies that material and fiber grating current
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