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Theoretical Model Building And Experimental Research Of The Time Difference Fluxgate Magnetometer

Posted on:2016-06-04Degree:DoctorType:Dissertation
Country:ChinaCandidate:B YangFull Text:PDF
GTID:1108330482467732Subject:Instrument Science and Technology
Abstract/Summary:PDF Full Text Request
Fluxgate sensor is a magnetic field detection equipment base on the nonlinear magnetization characteristics of the soft magnetic materials. Because of the excellent performance in sensitivity, resolution and the ability to feel vector magnetic field, the fluxgate sensors find applicability in fields such as geological exploration, navigation, space and so on. As the influence of the odd harmonic noise in conventional fluxgates, promoting the sensitivity, resolution and stability of fluxgate is limited. A novel residence time difference (RTD) fluxgate is put forward to avoid the odd harmonic noise. The RTD fluxgate gain the target magnetic field from the difference time of residing in the positive and negative saturation state under periodic saturation magnetization of the core. Because of simple structure, low power consumption, RTD fluxgate would be a new research direction.By analyzing the characteristics of the RTD fluxgate with the core material and the structure of the sensing element, a modified hysteresis model is proposed in this dissertation. A RTD fluxgate prototype is designed and tested. According to the double potential well of the soft magnetic material, a novel fluxgate dived by the gauss noise is manufactured and the performance of the fluxgate is obtained by a prototype. Main research work can be summed up in the following aspects.(1) A modified hysteresis model based on the Brillouin equation is proposed by researching the particularity of the hysteresis loop in the core of RTD fluxgate probe. Fitting precision of the model and the experimental hysteresis loop is promoted by adding the demagnetization factor to the modified hysteresis model.(2) In order to provide the standard on selecting the core material, the relationship between the model parameters and the waveform of the dynamic permeability is researched according to the modified hysteresis model. By analyzing the transverse effect of the fluxgate probe with closed magnetic circuit structure, a guide to design the structure of the RTD fluxgate probe is presented.(3) The excitation signal generator, the conditioning circuit and the time difference readout circuit are designed with FPGA microprocessor control. Through the experiment of different material, size of the core and the structure of the fluxgate probe, the prototype of the fluxgate is manufactured. The prototype shows an excellent performance on stability and resolution by the fluxgate characteristic test.(4) According to the double potential well of the soft magnetic material, the relationships between the magnetic field and the steady state transition rate of a bistable system excitated by a gauss noise is established. A novel fluxgate sensor with Gauss noise and weak sinusoidal signal excitation is designed. By discussing the relationships between the transition rate curve and the above factors under period excitation using numerical simulation, the expression of the time-difference and the external magnetic field is derived.(5) The prototype of the noise excitation fluxgate is fabricated by the proposed principle. The relationships among the transition rate and the external magnetic field, noise intensity are confirmed by the experimental results. And the performance of the prototype is also tested. Comparing to the RTD fluxgate, the noise excitation fluxgate has a higher sensitivity and more stability...
Keywords/Search Tags:fluxgate, residence time difference, hysteresis loop, bistable system, transition rate of steady state, gauss noise
PDF Full Text Request
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