Research On Current Sensor Based On Fiber Bragg Grating

Current is the key parameter of monitoring and equipment protection in the electric field. Accurate current measurement can ensure the electric power equipment to operate safely. Pulse high current is an important factor which causes damage of power system. Real-time monitoring current value is the key link to the maintenance of stable operation of power grid system. In the practical application of electrical field, studies of current sensor have been occupied an important position. The research of optical current transducer becomes the focus and direction. At present, the existing fiber Bragg grating current sensor has its own advantages and disadvantages in the practical application. Many researchers had conducted the research plan that the stack piezoelectric ceramic was used as the sensing material. Although it had achieved good precision, there still existed problems such as the low efficiency of energy transfer and the poor linearity of the measurement in low magnetic field. Comparing the giant magnetostrictive materials and the stack piezoelectric ceramics, the giant magnetostrictive material has more obvious advantages. To sum up, the application of giant magnetostrictive material in current sensor is the trend of the future research.In this paper, a scheme of optical fiber Bragg grating current sensor based on giant magnetostrictive material was proposed. The heavy power frequency current flowed through the Rogowski coil to get the sampling current. Sampling current flowed through the drive coil to produce certain intensity magnetic field. The adhesive fiber Bragg grating stretching was driven by the giant magnetostrictive material under the magnetic field force. The method of measuring current value was by measuring the center wavelength variation. Using ANSYS finite element analysis software determines the diameter of the drive coil. According to the simulation, the drive coil generates the magnetic field strength in the linear region of the giant magnetostrictive material. A control system of DSP based on TMS320F2812 has been designed. The built-in A/D conversion module is used as the signal acquisition device. The correction algorithm for improving the sampling precision has been studied. Secondly, the software of the system has been designed.It has realized the functions including collection of high-speed voltage signal, LED displayed and serial communication. Lastly, the whole experiment system is set up.In the A/D acquisition experiments, the displayed signal waveform is observed by the host computer. The measurement errors are less than 0.5%. Inputting the current of 0A to 100A, the value of the center wavelength of fiber Bragg grating is measured, which verifies the the feasibility of the system.