Research On Magnetic Hysteresis Suppression Methods For High Performance Magnetoresistance Sensors

With the rapid development of applications of weak magnetic detection such as unmanned aerial magnetic anti-submarine,geomagnetic navigation and intelligent magnetic fuze,high performance small three-axis magnetic sensors are urgent needed.However,the hysteresis in the output response seriously affects its performance.Supported by the National Natural Science Foundation of China,this paper focuses on the hysteresis problem in the magnetoresistive sensor and studies the suppression method : a T(x)hysteresis model of GMR magnetoresistive sensor is established,and a magnetic field tracking compensation method based on T(x)model is proposed to suppress the effect of hysteresis;Through the design and preparation of micro-compensation structure,and the development of the corresponding compensation hardware and software systems,the final experiment verifies the correctness of the GMR magnetoresistive sensor T(x)model and the effectiveness of the magnetic field tracking compensation method based on the T(x)model for hysteresis suppression.By analyzing the principle of hysteresis in multilayer GMR magnetic sensors,an improved T(x)hysteresis model for multilayer GMR magnetoresistive sensors is derived based on the traditional T(x)hysteresis model.In order to reduce the linear approximation error in the magnetic tracking compensation method,a magnetic field tracking compensation method based on the T(x)model,and taking the multi-layer GMR magnetoresistance sensor as an example,this method is proved theoretically to suppress the hysteresis and improve the accuracy of the magnetic signal measurement.Aiming at the key performance parameters such as excitation coefficient,resistance and inductance,the finite element simulation design method of compensation coil is established,and the optimal design of compensation coil and hysteresis compensation structure is realized;through the introduction of micro-plating technology,the high-density large thickness compensation of the micro-coil high-quality preparation process is broken through.By introducing a buffer layer and adopting a high-precision optical alignment system,a three-dimensional high-precision mounting of the sensitive body is realized,and then the preparation of a high-performance hysteresis compensation structure is completed.Using high-resolution DAC and voltage-controlled constant current source technology,developed a high-precision low noise compensation / pulse current generation circuit.Using orthogonal phase lock parameter estimation and digital PI current control algorithm,magnetic field tracking compensation and GMR magnetoresistive sensor operating point control are realized.The hysteresis tracking compensation test based on T(x)model is carried out by setting up a hysteresis compensation test platform.The error of the fitted model is 0.31% for the improved T(x)model;magnetic field tracking compensation based on the T(x)model is compared with the direct magnetic field tracking compensation method.The hysteresis is reduced from 1% to 0.4%.