Research On Electromagnetism - Induced Electro - Telescopic FBG Magnetic Field Sensor

Magnetic field is able to deflect the needle, which can also have the magnetic force to the magnet in it. With the rapid development of technology, the problem of magnetic field measurement is closely related to many areas of industrial production and scientific research, such as magnetic prospecting, geological exploration, magnetic navigation, with median separation, controlled thermonuclear reactions and artificial earth satellite, etc.In recent years, the measurements of the magnetic field are varied, but most of the sensors often take use of the electromagnetic measurements, these magnetic sensors used in industrial production, which are often confined to take anti-explosion, anti-spark measures and some other measures. In recent years, a new type of fiber-optic sensing technique becomes more and more popular, and it has been widely used in many testing areas and industries as a result of the advantages of strong insulation, anti-electromagnetic interference, fast signal transmission, and also it can achieve the advantages of distributed measurement.In this paper, by combining the fiber grating sensing technique with electromagnetic induction principle and inverse piezoelectric effect of stack piezoelectric ceramics, a fiber Bragg grating sensor based on the inverse piezoelectric effect and electromagnetic induction principle is developed. Since the sensor itself has inherent advantages of fiber Bragg grating, it can be applied to the petroleum, chemical, coal, metallurgy and other flammable and corrosive environments. The main contents of this paper are as follows:1. A fiber Bragg grating sensor model is established based on the inverse piezoelectric effect works and electromagnetic induction principle, and a fiber Bragg grating magnetic field sensor is designed.2. According to the design of magnetic field sensor, it is necessary to take some measures, such as the mechanical components of the sensor’s selection and processing. The motor’s speed is closed-loop controlled through the PWM pulse width modulation by using MCU and driver board, in which can keep the motor’s speed constant. It can easily calculate the theoretical value of the sensor according to the mathematical model of the material and the size of the sensor. The theoretical calculations show that the sensitivity of fiber Bragg grating magnetic field sensor is0.1218pm/G, its resolution is8.21G.3. The main work of this design is assembling the various parts of the sensor, and testing the main components of performance, including testing the speed of DC drive motor by controlling the duty cycle of the PWM pulse width to control the motor’s speed, testing of piezoelectric ceramic’s working linear areas, performance testing of strain transfer relationship between piezoelectric ceramic and fiber Bragg grating, as well as builting the test platform to satisfy the functional requirements of the different components, and also analyze the data results of the test.4. According to the magnetic field sensor’s testing requirements and the state’s test specifications, built a test system throughout the magnetic field sensor, carried out the pros and cons of repeatability test to the magnetic field sensor designed in this paper, and also analyzed the test data of this sensor. Test results show that the sensitivity of the magnetic field sensor is0.113pm/G, the nonlinear error is5.45%FS, the repeatability error is6.29%FS, the hysteresis is6.61%FS.