Optical Fiber Current Sensor Based On MEMS Technology And Magnetic Field Gradient Force

Fiber-optic current sensors are widely used because of their wide measuring range and good insulation,which are compatible with the needs of digital power grids.This article introduces the sensing principle based on Fiber Bragg Grating(FBG)and the fiber current sensor based on the Fabry-Perot(F-P)interferometer principle,designs the sensing unit and conducts experimental analysis.Based on the finite element analysis method,the magnetic circuit structure of the optical fiber current sensor was designed by ANSYS Maxwell simulation software,the position of the sensing unit in the magnetic circuit was determined,and the excitation coupling structure of the current sensor was clarified.And continue to optimize the magnetic circuit structure,increase the magnetic field gradient value on both sides of the sensing unit,and improve the sensitivity of the optical fiber current sensor.The sensor unit of the fiber grating current sensor was designed and manufactured,and the structural design of the sensor unit was optimized by mechanical simulation of the sensor unit of different sizes,and the size of the sensor unit was determined.Based on the sensing principle of fiber grating and the force of the sensing unit in the gradient magnetic field,the sensing mathematical model of the sensor is established.Based on the demodulation principle of the spectrometer,the fiber grating current sensing measurement system is constructed,and a certain range of current measurement is realized.The sensing unit of the F-P optical fiber current sensor is designed and manufactured based on MEMS technology.Through mechanical simulation of sensing units of different sizes,the structural design of the sensing unit is optimized and its size is determined.Based on the theory of small deflection,the deflection of the sensing unit is analyzed,and the sensing mathematical model of the F-P sensor is established.Based on the principle of F-P interferometer and the principle of DFB sideband demodulation,an F-P optical fiber current sensing measurement system is constructed and experiments are carried out.The experimental results show that the current range of the sensor is significantly higher than that of the aforementioned sensor,and as the applied current increases,the sensitivity and accuracy of the F-P fiber optic current sensor also increase,achieving the expected effect of the design.