Research And Design Of Digital Fluxgate Sensor Based On FPGA

Fluxgate sensor is a vector sensor that measures a weak magnetic field.It has the advantages of small size,simple structure,high resolution,etc.It is widely used in earth geological survey,aerospace exploration,national defense military,industrial automation,biomedical community and other fields.Weak magnetic field measurement is realized by using the nonlinear relationship between the magnetic induction intensity and the magnetic field strength of the high permeability core in the measured magnetic field under the saturated excitation of the alternating magnetic field.In the early days,traditional fluxgate sensors were mostly analog,and their internal circuits were mostly composed of analog devices.Not only did they have large mass and volume,high power consumption and complicated structure,but they were also easily affected by temperature,resulting in low accuracy and difficulty in adapting.Magnetic measurement occasions with increasingly strict accuracy requirements.With the development of digital circuits,digital fluxgate sensors have emerged.Digital sensors not only overcome the shortcomings of analog sensors,but also have higher accuracy,resolution,and sensitivity,and are in line with the trend of miniaturization of equipment,and have very good development prospects.Compared with using single chip microcomputer or DSP chip as the core of the digitalization scheme,this paper expounds the basic principle of measuring magnetic field of fluxgate sensor on the basis of investigating a large number of related materials,and designs a digital closed loop feedback magnetic flux based on FPGA Door sensor.The second harmonic detection method is used to measure the magnetic field and design related hardware circuits.The hardware circuits are divided into excitation circuits,induction circuits,and feedback circuits.Using FPGA field programmable logic gate array as the main control chip,taking advantage of its parallel operation processing speed and on-chip programmable features,it replaces the analog device circuit for signal processing,and performs digital detection and filtering within the FPGA to improve the system's Anti-interference and signal-to-noise ratio.Using high-precision digital-to-analog conversion and analog-to-digital conversion chips to collect data to improve the overall system accuracy.At the same time,the design of the feedback loop constitutes a closed-loop feedback control system to improve the stability of the system,expand the dynamic measurement range,and reduce the degree of nonlinearity of the system.The designed sensor can measure the magnetic field in three axial directions.The host computer interface is written in C #,and the test data is displayed on the host computer in real time through serial communication.Using a digital solution effectively overcomes the temperature drift effect of analog sensors,reducing volume and power consumption.The test results show that the designed closed-loop feedback fluxgate sensor has stable performance with a range of ± 65 000 n T,and a good linearity within the range,and the resolution is less than 1n T,which can achieve the measurement of geomagnetic field.