Study On FBG Current Sensing Technology

With the development of electric power industry, traditional currentsensors can not satisfy the requirement of industry commendably in somespecial condition. Fiber current sensor will be a preponderant substitute, due toits good electric insulation, resistance of the interference of electromagneticand corruption, small volume, light weight, high-sensitivity and strongcapability of multiplexing. Fiber and FBG current sensor have a goodforeground in the future.The subject of this paper is FBG current sensing technology, and we makea deeply and systematically research on FBG sensing theory and experimenttechnology.FBG sensing technology and its recent progress in applications isintroduced systematically;the coupled-mode theory and the sensing principleof FBG are expatiated and the Bragg formula and reflectivity formula arededuced;the work principle, variety and essential characteristic of PZT areexpatiated in detail, and the configuration of PZT parts of an apparatus issummarized. The mechanism of piezoelectric electrostriction is analyzeddeeply, and the normalized control model is introduced aiming at analyzinghysteresis characteristic, and an electrical polarization intensity (charge) control methodbased on the aforementioned model which can effectively reduce the hysteresischaracteristic is discussed.A novel current sensor based on FBG controlled by PZT is designed andthe current sensing principle formula, namely the relationship of currentintensity and Bragg wavelength is deduced. The performance of FBG currentsensor is tested, and the experimental result is consistent with theoreticalanalysis.An enhanced-sensitivity scheme is presented. We design the enhanced-sensitivity structure and study the scheme experimentally. The sensitivity isincreased 2.2 times which is 1.6×10-3 nm/A in the 0~2 A range of electricityintensity, and the linearity of current response is good. Accordingly, we realizethe FBG current sensing technology.