| Fluxgate sensor is a magnetic field sensor with very good comprehensive performance. It has been widely used in the fields with high precision and high stability requirements, such as aviation, aerospace, geological exploration, petroleum logging, and so on. Saturation excitation working mode not only causes high power consumption but also makes fluxgate modeling difficult. In the fluxgate sensor design process, the current analysis method with finite element software to determine the design parameters is time consuming and needs complicated meshing. Fluxgate sensor performance depends on probe, excitation circuit and signal processing circuit. It is very difficult to obtain the best performance by designing these three parts separately. To obtain best performance, co-simulation of the probe, the excitation circuit and signal processing circuit is very essential. Simulation program with integrated circuit emphasis(SPICE) has played a huge role not only in the integrated circuit design simulation field, but also in other physical devices modelling and simulation. In order to realize co-simulation of the probe, the excitation circuit and signal processing circuit, the key is the accurate fluxgate SPICE model establishment. This paper mainly studies the fluxgate SPICE modeling method.The main innovative achievements of this dissertation include:(1) A simple method for the Jiles-Atherton-Brachtendorf model parameters extraction was proposed using the initial magnetization curve, the coercivity and remanence. One of the difficulties in fluxgate SPICE modeling is the fluxgate core magnetic properties modeling. Although Jiles-Atherton and Brachtendorf‘s core hysteresis loop model is suitable for SPICE implementation, however, the determination of the model parameters is very complex, and the selection of a suitable initial value is very difficult. The proposed method needs only the initial magnetization curve, the coercivity and remanence to determine the model parameters, the calculation process eliminates the discretization of the nonlinear equations, thus greatly simplifying the computation.(2) A hysteresis loop SPICE model taking skin effect into account was proposed. Considering skin effect, it is necessary to compute the distribution of the magnetic field and the magnetic flux density in the cross-section of ferromagnetic materials sheet in the dynamic mode. However in the present hysteresis SPICE model the magnetic flux density is assumed uniform in the cross-section of ferromagnetic materials sheet. By analyzing the magnetic field produced by eddy current, the hysteresis loop SPICE model taking into account skin effect was obtained. Compared with the present hysteresis SPICE model, the proposed new model is more accurate.(3) This paper proposed a method for automatically generating fluxgate SPICE model based on integral equation method using magnetic field and a method for automatically generating fluxgate SPICE model based on integral equation method using magnetic scalar potential. In order to realize co-simulation of the probe, the excitation circuit and signal processing circuit, it is not only required that the fluxgate SPICE models should consider the fluxgate core shape, the core material performance, coil position, a coil winding method and excitation conditions and other factors, but also required that the parameters can be adjusted conveniently. To solve this problem, a method for automatically generating fluxgate SPICE model based on integral equation method using magnetic field and a method for automatically generating fluxgate SPICE model based on integral equation method using magnetic scalar potential were proposed. The model not only computes fast, but also accurately considers the fluxgate structure parameters, the excitation conditions and other factors. The model simulation results agree well with the experiment results and the finite element software simulation results. With the proposed fluxgate SPICE model automatic generation method, the fluxgate structure parameter setting is convenient. Inputting the structure parameters of fluxgate and core material parameters, then the corresponding fluxgate SPICE model can be fast established.(4) A fluxgate SPICE model based on integral equation and interpolation method was proposed. Compared with the finite element method for analyzing the fluxgate, the computing time with fluxgate SPICE model based on integral equation method was shortened greatly. But it still appears to be slower for some specific application, for example, repeated simulation tests were required to determine the optimal structure parameters and excitation parameters. For fluxgate SPICE model based on integral equation and interpolation method, relationship between current and flux of the receiving coil, and relationship between the measured magnetic field and bias current were analyzed when model establishment. Therefore, the receiving coil flux can be obtained without computing magnetic field magnetization for each grid in the repeated parameters test, reducing the unknowns to be solved effectively, then the model has fast calculation speed. The SPICE model simulation results also agree well with the finite element software simulation results, especially when the excitation current is large or the magnetic field is small, the SPICE model simulation results and the finite element results almost coincide.The research contents of this dissertation were combined with the National Natural Science Foundation of China called "Study on the low-power technology of microfluxgate" and Specialized Research Fund for the Doctoral Program of Higher Education of China by the name of "Study on the low-power technology of micro-fluxgate based on soft magnetic thin film with porous". The research of this dissertation will be of great beneficial in improving the performance and saving the cost for micro-fluxgate. The research results can be used in many fields like aerospace, micro-satellites, small unmanned aerial vehicles, biomedical, current measurement, degaussing, traffic control, automotive, and so on.
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