Study Of Fluxgate Sensor With Dual Magnetic Circuit And Magnetic Field Measurement System

Magnetic field measurement has been deep into all areas of space science,national defense science, biomedicine, geophysics and industrial inspection,detection methods become indispensable. But as the existence of a weak signal,is susceptible to excitation signal interference problem and measurement of the magnetic field, the impact of the specific application. Therefore, researching on new magnetic sensor and detecting method are very necessary.This paper proposed a dual fluxgate sensor structure on the basis of a large number of literatures on the magnetic field measurement, and developed the corresponding magnetic field measurement system, mainly including fluxgate sensor, incentive system, detection system and other main modules. First discussed the basic principle of the fluxgate technology, elaborated the essential difference between the transformer effect and magnetic fluxgate effect. On the basis of this theory, developed a new type of magnetic fluxgate sensor, and gived the mathematical model of the designed sensor, this paper has also analyzed the characteristics of the structure.The fluxgate sensor transformer effect and square wave incentive fluxgate prone to the problem of harmonic interference, the design of using a sine wave excitation of fluxgate excitation system. The incentive system has a strong versatility, you can switch to achieve square wave and sine wave excitation, the bandwidth of the system is 1k Hz to 4MHz, the excitation signal output current is0.03-3A. On the analysis of the design of magnetic fluxgate sensor output signal based on the characteristics of by mature second harmonic method, is developed and the corresponding detection circuit, analog lock-in amplifier is designed,extraction and the measured magnetic field related to the second harmonic signal,magnetic field signal data display is realized through the data acquisition system.This paper built a test platform of system, determining that the sensor undersine wave excitation optimal excitation frequency is 16 k Hz. And test results are given in the paper: the excitation current is 200 m A, the power consumption of the sensor is 160 m W, the measuring range is 0-3m T, the sensitivity of 1.1(m V/T),resolution 0.99μT. The experimental results show that this system can realize the measurement of the small range of magnetic field intensity, which lay a foundation for practical.