Research And Design Of Hybrid Magnetometer Based On Fluxgate And TMR

The frequency domain electromagnetic method(FDEM)is one of the important methods of geodetic resource exploration.The detection magnetic field frequency ranges from 0.1m Hz to hundreds of k Hz.In magnetic anomaly detection applications,the magnetic anomaly value is usually very small,ranging from f T to several n T,so higher requirements are imposed on the working frequency and detection accuracy of the magnetic sensor.So,we designed a hybrid wideband magnetic sensor based on a fluxgate and TMR,which aims to solve the problem that many low-noise magnetic sensors have a low operating frequency band to meet the multi-purpose requirements of magnetic field measurement.Fluxgate sensors have low noise at low frequency noise and have high noise at high frequency,wide measuring magnetic field range.However,it have low operating frequency.TMR sensors have low power consumption and high operating frequencies,but noise high at low frequency.In this paper,the characteristics of the fluxgate sensor and TMR sensor are "complementary" in the operating frequency band and noise characteristics.According to the idea of complementary filtering data fusion,after lowpass and highpass filtering are performed on the fluxgate and TMR,respectively,On the FPGA platform,the data fusion method of digital filtering and comparison is used to “splice” the output of the two sensors in the frequency band to achieve the data fusion of the two magnetic sensors,thereby achieving the expansion of the magnetic sensor operating frequency and simulation through Simulink.Tool,the feasibility of the fluxgate and TMR data fusion method is simulated,and the feasibility of the method is verified.The dissertation analyzes and designs the hardware circuits of the fluxgate and TMR hybrid magnetic sensors and the key modules of the hybrid magnetic sensors,including hardware circuits such as ADC,DAC,FPGA,etc.,completes the prototype production of the hybrid sensors,and passes the existing instruments in the laboratory.The equipment has built a hybrid sensor test platform to test and verify the prototype of the hybrid sensor,including verification of functional modules,calibration of the sensitivity of the fluxgate,TMR and hybrid sensors,and testing of noise and sensor frequency response.The test results show that the prototype of the hybrid sensor prototype has a peak-topeak noise background of 0.8n T,a sensitivity of 0.113 m V/n T,a magnetic field measurement range of ± 0.8Gs,and a working frequency from DC to 10 k Hz,thereby expanding the frequency range of the existing magnetic sensor and solving the The problem of low working frequency of the fluxgate validates the feasibility of the above method.