Current sensor based on giant magnetostrictive material and fiber Bragg grating

A new type of fiber optical current sensor was designed. The sensing head was made by holding a fiber Bragg grating (FBG) on a giant magnetostrictive material (GMM) rod along the axial direction. The sensing head was put into one of the air gap of two silicon plate magnetic cores wound by enameled cable. In order to improve the linearity of the sensor, another silicon plate core with coil was inserted into the other air gap to provide a biased magnetic field for the Terfenol-D rod. The Terfenol-D rod was elongated in the magnetic field varying with the measured current and the strain caused the shift of the center wavelength of FBG. In certain biased magnetic field, the relationship between the measured current and the wavelength shift is linear. Experimental results show that the linear tuning range of FBG is 0.07nm when the measured current of the winding is 0~3A. The corresponding measurable current of straight conductor is 0~ 2313.07A on the assumption that the distance between the axis of the straight conductor and the GMM rod is 10mm.