Mechanism Research And Device Design Of Magnetic Field Sensors With New Magnetoelectric Composite Structure

The magnetoelectric composite structure combines the ferromagnetic material and the ferroelectric material,and the energy can be freely converted in the magnetic field and the electric field through the stress/ strain as the medium.The magnetic/ electric signal can be converted into the electric/ magnetic signal.Considering that the composite magnetoelectric structure usually has a strong magnetoelectric coupling coefficient,it has a very important application prospect in the preparation of new multifunctional magnetoelectric devices,especially the weak magnetic field sensor.Therefore,exploring and designing a new magnetoelectric composite structure to further improve the magnetoelectric coupling strength and sensor performance,as well as carrying out circuit design around the magnetoelectric composite structure sensing unit to miniaturize and integrate the sensor,etc.,will help promote the magnetoelectric sensor.Based on the above considerations,this paper carried out the following research:First,considering the nonlinear characteristics of magnetostrictive strain,the nonlinear magnetostrictive constitutive relationship is used to establish a finite element simulation model of the magnetoelectric composite structure in the COMSOL Multiphysics simulation software.After verifying the effectiveness of the model,the finite element simulation model of the embedded magnetoelectric composite structure is constructed by using the constitutive equation of the embedded magnetoelectric composite material,the stress-strain relationship of the material,and the corresponding boundary conditions.The simulation results are compared with the existing experimental results,which proves the validity of the embedded magnetoelectric composite structure model and the reliability of the prediction results.After that,the combination of different magnetostrictive materials and piezoelectric materials and the change of the geometric configuration of the piezoelectric materials are selected.From these two aspects,the influence on the performance of the magnetoelectric composite magnetic field sensor is studied.The prediction results show that the combination of PZT-Ni is the best choice.When PZT is round and diamond,the performance of magnetoelectric sensor is better than PZT is square.Secondly,four new geometric configurations of embedded magnetoelectric sensors were designed,and the magnetoelectric performance of the four new configurations was studied through model simulation.Next,the above four magnetoelectric composite structures were prepared through experiments,and the experimental test results were basically consistent with the conclusions drawn by the simulation.Through the calculation results of the model,the stress distribution of the four configurations is analyzed,and the effects of different geometric configurations on the magnetoelectric properties are studied.The results show that the magnetostrictive material is diamond-shaped and the piezoelectric material is square.The magnetoelectric coefficient is ?=460m V/(cm·Oe);the magnetostrictive material is square,and the piezoelectric material is diamond-shaped with the worst magnetoelectric performance,and the magnetoelectric coefficient is?=390m V/(cm·Oe).In addition,the effect of the aspect ratio of the effective length on the magnetoelectric coupling performance of the embedded structure is further studied.When the optimum aspect ratio is 1.5,the magnetoelectric coupling performance is the best.Finally,when considering the practical application of magnetoelectric sensors,it is necessary to consider both the strong magnetoelectric coupling performance of the sensor and the miniaturization and integration of the device.Therefore,the flexible piezoelectric material PVDF and the magnetostrictive material Metglas were selected to construct a flexible magnetoelectric composite material,and a flexible tri-layer magnetoelectric composite material was prepared as a sensing unit through experiments.After that,a phase-locked amplifier circuit module was designed,and the test results of the magnetoelectric sensor added to the circuit module were compared with the test on the test platform using a phase-locked amplifier.The effectiveness of the designed circuit module is confirmed.In this paper,considering the nonlinear multiphysics coupling effect,a numerical simulation model of laminated and embedded magnetoelectric composite structure is constructed to predict and guide the design of a novel magnetoelectric composite structure with strong magnetoelectric coupling.After that,the experimental preparation of the embedded magnetoelectric composite structure sensor with different geometric configurations was verified by experiments,which has important reference value for the subsequent magnetoelectric sensor in the research of coupling mechanism and new configuration design.In addition,the development of weak signal acquisition and processing circuit design,and the combination of flexible magnetoelectric sensors for experimental tests have promoted the miniaturization,integration and industrial application of magnetoelectric sensors.