Research On The Residence Time Difference Fluxgate

Residence Time Difference Fluxgate is the magnetic sensor which is based onmeasuring the time difference of the magnetic state. It has the characteristic that thereis not affected by the odd harmonic in it. Especially it has a smaller volume and lightweight. Therefore, the Residence Time Difference Fluxgate has excellent prospects infurther improving the accuracy and resolution. Because of there are less domesticresearches about the Residence Time Difference Fluxgate, the basic principle analysisof the Residence Time Difference Fluxgate, modeling and correction of the hysteresisloop, the physical parameters of the fluxgate probe, architecture of the digital fluxgateand stochastic resonance phenomena of the fluxgate has been researched in the article.The exploratory work of developing of the Residence Time Difference Fluxgate hasbeen completed. The main work and results of the paper are as follows:1） The fundamentals study of the Residence Time Difference Fluxgate. Basedon the assumptions of the hysteresis loop of the core is ideal, the theoretical formulaof the Residence Time Difference Fluxgate has been derived. Under this premise, therelationship between the target magnetic field and the time difference has beenstudied with the triangle wave or sine wave as the excitation field.So is the correspondding sensitivity.2） The new model of hysteresis loop has been researched. The model based onthe arctangent with coercive force and dynamicf permeability worked out the problemthat there is no proper model for the RTD fluxgate time domain research and how tochoose the material of RTD fluxgate probe. There are two main innovations in thenew hysteresis loop，Respectively, is the introduction of the parameters and the modelof the coercive force by using a dynamic permeability parameter. Introduced coerciveforce parameters to the model can be applied to the time difference fluxgate principlewith. The role played by the coercive force parameters in the time difference fluxgateis clear by the results of the model calculations. The lowest value of the excitationmagnetic field because the coercive force directly affects the emergence of the peakposition and the time difference. Therefore, it is a very important parameter in themodel. Coercive force write the model parameters by using the sign function method, The model can be used directly derived analytically, Solve the former involvescoercive force model needs to proration shortcomings; Dynamic permeabilityparameters make the model more accurate, Solve the original arctangent model of themagnetic induction over zero will produce larger deviations, While addressing theoriginal arctangent model curvature fixed, Unable to distinguish between the problemof the similarity of the two cores. Adding coercive force model using dynamicpermeability can also reduce the excitation magnetic field extreme value at step, tomake the model more accurate, higher accuracy. Use of introduction of the coerciveforce and the dynamic permeability arctangent model, Not only provide a theoreticalbasis for the study of the time difference fluxgate, and provide the basis for the timedifference type the fluxgate core material selection, you can also take advantage of thetheoretical introduction of the time difference fluxgate circuit noise intensity.3） The research on the relationship about excitation magnetic field and modelparameters. Under fitting the model with many excitation magnetic field,the functioncan be proposed. The errors between parameters computed by the function and theparameters fited by the model is less than5%. The model can also be applied to thestudy of other needs hysteresis loop model. For a core, Using the model of eachparameter and the relationship of the excitation field can be derived for the shape ofthe hysteresis loop in the under arbitrary excitation magnetic field is, Provides aconvenient and theoretical basis for the study of many materials can not directlymeasure the hysteresis loop.4） The preliminary comparative test of the probe design of time differencefluxgate. Depending on the different physical characteristics of the probe, from thepoint of view of the detect ion difficulty, explore the structure of the probe core, theinfluence of the winding programs on the output characteristics of the probe, mainlyinduced electromotive force. Followed by comparisons and instructions of theperformance of the core materials, the existing materials are brief analyzed. The moreappropriate core materials of time difference fluxgate are proposed.5） According to the problems encountered in the preliminary experiment, thestochastic resonance phenomenon of time difference fluxgate has been found bymaking use of simulation. Then the method about feedback is proposed by stochasticresonance phenomenon to improve the sensitivity of the time difference fluxgate. Thesimulation shows that with the method of using linear feedback, the parameters of the system’s inherent coercive force has been changed, and with coercive force reduced,the exciting magnetic field which is subjected to the coercive force can be furtherreduced, which can achieve the purpose of enhance the time difference fluxgatesensitivity. The shape of the potential well of the system by using cubic feedbackmethod can be changed, thus the value of optimum stochastic resonance noise willchange, too. Matching the optimum noise of system with external noise intensity bythe initiative adjust of system, it can reach resonance state. Then we can also improvethe sensitivity of the time difference fluxgate.6） Basic performance testing of static indicators of the time difference fluxgate.According to the basic requirements of the sensor test, the time difference fluxgatemeasurement range, linearity, dynamic range, and other basic indicators of the testtime difference fluxgate meet the basic indicators of the current magnetic explorationand measurement needsconclusion. Test of basic indicators, given the time differencefluxgate parameter range and the direction for the time difference fluxgateapplications.The innovation of this paper is mainly reflected in the following aspects:1） Put forward the model contain the parameters of the coercive force hysteresisloop and solve the problems of the original hysteresis loop model involving coerciveforce parameters can not resolve the derivativly. Before the model in the paper, almostall the research on the hysteresis loop model has rarely involved in the coercive forceparameters. Once the research involves the coercive force parameters, the use ofalmost all is piecewise function method. The piecewise function biggest problem isnot conducive to view the role played by the coercive force throughout the course ofthe study, and not conducive to intuitively find the relationship between the coerciveforce and the object of study. In this article with the coercive force parameter modelproposed to solve the conventional relates coercive force requires segmented solvingproblems. Will take coercive force of the magnetic hysteresis model is applied to timedifference type magnetic gate can more easily find coercive force to the influence oftime and coercive force the existence of the influence of the output signal delay.Hysteresis loop model with a coercive force can be further applied to a series of usedmagnetic core device power consumption calculation, and provide theoreticalreference.Changing the arctangent model’s magnetic permeability parameter to thedynamic parameter can reduce the model’s fitting errors caused by the fixed curvature. Arctangent model of the hysteresis curve is sufficient in the nonlinear models, themain problem of the model is the magnetic permeability parameters are constants.The arctangent model is in accordance with a substantially constant curvaturevariation and can’t simulate the nonlinear characteristics of the hysteresis curve well.By introduction of dynamic magnetic permeability parameter, the curvature of thearctangent model can change dynamically as needed. So, the arctangent model get abetter simulation results of the hysteresis curve’s nonlinear characteristics. Theoriginal arctangent model’s maximum errors, which are caused by the zero crossingmagnetic induction and the extreme position of the excitation magnetic field, can bereduced to an acceptable range (<5%).2）The function about the parameters of the model and the excitation field hasbeen found, which solved corresponding model of excitation of magnetic field and themagnetic permeability the is established. Previously, none of the model gives the linkbetween the magnetic permeability and incentives. In this paper, the arctangent modelapproximately gives relationship between permeability and excitation field, and thatprovide reference and solutions for the other studies on permeability. On the dynamicpermeability model that the order is five, The fitting residual magnetic permeabilityparameters on the magnetic permeability is small, and that meets the need for thestudy of the magnetic permeability. Thus the permeability changes under arbitraryexcitation field can be calculated directly without measurement, and the study onmagnetic permeability is easier.3） Based on stochastic resonance phenomenon of time difference fluxgate,putting forward the application feedback methods to improve the sensitivity of thetime difference fluxgate. Time difference fluxgate has similar characteristics of thesystem with Schmitt trigger, while the input signal is also a regular cycle signal, sothe time difference fluxgate meet the prerequisites of stochastic resonance. Thestochastic resonance phenomenon of time difference fluxgate can be observedvisually by simulation. According to the research results of stochastic resonance,adjusting parameters of the time difference fluxgate whose parameters are fixed byusing feedback on the system, then the higher sensitivity of time difference fluxgatecan be obtain. By using linear feedback lower threshold of time difference fluxgatecan be obtained, with reducing the incentive intensity, the sensitivity of timedifference fluxgate can be increase with less power consumption; using cubic feedback can change the shape of potential well of the time difference fluxgate andthus the time difference fluxgate can take the initiative to adapt to the noise, thenreach the purpose of matching the optimal noise system with outside noise, andother high-level feedbacks have a similar effect.