Design And Research On Flux-gate Instrument

Fluxgate magnetometer, also known as the magnetic saturation magnetic sensor, isa magnetic measuring device which is designed according to Faraday’s law ofelectromagnetic induction by selecting the soft magnetic material with high permeability(the most common are Po Mo alloy, cobalt based amorphous alloy) as core material. Asone kind of magnetic sensors, magnetic flux gate can be applied in many scientificresearch fields. Since the fluxgate sensor can be applied under the test environment ofhigh-speed movement, especially under the environment of weak magnetic field, it iswidely used in physics, metal smelting, medical and military, geophysical survey,navigation and attitude determination, industrial automation and other fields. The weakmagnetic field detection technology is the most appropriate technology for conventionalearthquake omen and geomagnetic detection, therefore the magnetic field detectionbecomes a hot research field currently.Based on the study of a large amount of literatures about flux-gate magnetometer,this paper introduces the classification of flux-gate magnetometer and its developmentstatus and trend at home and abroad. It expounds the working principle of flux-gatesensor and shows how to establish the basic structure of dual core, choose soft magneticmaterials with good magnetic properties of Po Mo alloy as the core materialmagnetometer, design and manufacture the fluxgate magnetometer according to theeffects of the structure parameters on the induction signal. In flux-gate magnetometersignal processing circuit, we choose the second harmonic circuit as flux-gatemagnetometer sensor signal detection circuit, quartz crystal (2.4576M) as frequencysource, through the frequency division and power amplification processing after drivingsignal for flux-gate magnetometer. At the same time, we use the frequency divider to getreference signal in the same frequency source which is needed in phase-sensitivedetection circuit. This paper designs the corresponding LC resonance band-pass filtercircuit preamplifier circuit phase-sensitive detection circuit low-pass filter circuit andintegral circuit so that the flux-gate magnetometer can work normally, the output end of the output signal directly proportional with the measured magnetic field strength, and themeasuring magnetic field intensity displays in the form of the LCD. In addition, we dosome research and analysis on the causes of the formation of flux-gate sensor noise.Analysis results show that all the electromagnetic characteristics of the sensor probe andthe asymmetric shape size parameters will lead to the generation of noise. By analyzingthe noise frequency spectrum, noise is mainly composed of induction signal of thefundamental component and harmonic component of three times. At the same time, thepaper gives some suggestions about reducing the noise.The experimental results show that the flux-gate magnetometer has good linearity,little error of the system and high precision and meets the design requirements.