The Reseaches Of Magneto-optic Current Sensor And All-fiber Optic Current Sensor Based On Magnetic Fluids

At present, the study of the optical current sensor(OCS) is in a bottleneck stage, their birefringence and temperature factors has been a difficult problem to solve, which is also an important cause that the optical current transformer is difficult to promote in practical use. Many universities and research laboratories all further work on relevant experimental and theoretical research, but there is no real practical value breakthrough reported. However, compared to conventional current transformer, the OCS has many advantages, which makes the prospect of future electricity sector is very broad. In such cases, our group decided to participate in the study of OCS, hoping to have some innovation and breakthroughs. The main work is divided into the following three parts:(1) For the study of the OCS, this work was mainly to complete the building of experimental system, and some preliminary experiments for sensor head carried on before the application of the OCS. The building of experimental system includes the hardware establishment and signal processing software based on labview. A complete high current simulation system has been set up. The repeatability error, measurement range, sensitivity, and the influence of the source power for sensor have been measured and we get all performance parameters of sensor. We also do the experimental investigation on the relationship between the environment temperature and sensor. The last, we give a data model of the output with the changing of magnetic and temperature. We also put forward the solution of the temperature compensation method.(2) This article is not only to study the signal processing of the optical current sensor, but also for the innovative research about the all-optical current measurement methods. The use of novel materials-magnetic fluid with singlemode –multimode-singlemode structure(SMS) in all-optical current measurement was put forward. The novel sensor for current measurement based on the transmission intensity of the probe laser to measure the current,which can simplify the signal processing,and propose a new research direction in OCS. We first character the sensor in wavelength for light and then it was used for the current measurement. In order to improve the sensitivity of sensor, we put forward some novel scheme,such as we use a mirror to combine with the sensor. We also use a broadband light source to replace the narrow band laser. In order to ensure the accuracy of the experiment,we do simulation analysis for principle. We also do some experiment for the different angles between the axis of the sensor head and the magnetic field. We have investigated that the sensitivity of the sensor is most sensitive when the magnetic field is perpendicular to the senor.(3) At last,we shows an overall comparison of the two current sensing mode. We indicate the different of the signal processing for two sensor because of the different testing principles. The object detection by two sensors are also different in the future. The magneto-optic glass optical current transformer can be used in AC and DC,but the all fiber optical current sensor based on magnetic liquid is only can be used in DC. We believe that the full optical fiber current sensor based on magnetic liquid can be used in AC someday with our reacearch.