The Research On Temperature Compensation System For GMM-FBG Current Transformer Based On FPGA

The current transformer based on fiber bragg grating (FBG) and giantmagnetostrictive material (GMM) which has good insulation, strong anti-interference, high measuring accuracy, easy miniaturization, no explosion hazard,no liner birefringence and no power supply of high voltage electronic circuitbecomes a research hotspot in scientists. But the variations of environmenttemperature will result in inaccurate measurement because of FBG is sensitive tostress and temperature at the same time, and impact on the performance ofcurrent transformer. So the temperature compensation technology for GMM-FBGcurrent transformer is researched in this paper.On the basis of studying the work principle of GMM-FBG currenttransformer, this paper analyses many technologies of temperature compensationfor FBG, combines with the characteristics of GMM-FBG current transformer,embedded systems and signal processing technology, and proposes thetemperature compensation system for GMM-FBG current transformer based onField Programmable Gate Array (FPGA) by automatic tracking working point.The NiosII soft core was embedded in FPGA as a CPU of temperaturecompensation system, which will read and process the data in storage module.The data contains the AC component and the DC component, the AC componentis the measured variable, and the DC component is as the basis of adjusting theDistributed Feedback (DFB) laser. The processed date as a control of DFB laser is converted and outputted through the D/A module, and it automatically adjuststhe central wavelength of DFB laser following the change of the centralwavelength of FBG, so as to achieve automatic tracking of thequiescent operating point. So the function of temperature compensation isachieved.The temperature compensation system is tested on experiments platform.The experimental results show that there is a good consistent of the changingtrend between control voltage and temperature and the DC component outputtedfrom photoelectric amplifier remains constant in the changing process oftemperature. It shows that the temperature compensation system can well achievetemperature compensation for the GMM-FBG current transformer.