Research On Vibration And Noise Suppression Of Magnetoelectric Sensors

In today’s wide application of weak magnetic detection,magnetic field sensor based on magnetoelectric coupling effect has the advantages of high sensitivity,low power consumption,low cost,which makes it compared with other traditional high performance magnetic sensors such as fluxgate sensor and reluctance sensor,comprehensive advantages are obvious.However,in practical applications,especially for the moving platform in Marine magnetic exploration,due to the high vibration sensitivity of piezoelectric materials,the magneto-electric coupling weak magnetic sensor is not compatible with the platform environment,the signal drift is serious,the noise is high,and it is difficult to popularize the application.So far,in terms of vibration and noise suppression of magneto-electric coupled weak magnetic sensor,the intrinsic coupling performance of magneto-electric composite material and the detection ability of sensor have not been guaranteed simultaneously.Up to now,it has been found that the 2-1magnetoelectric coupling sensor in multi-push-pull mode has strong low-frequency magnetoelectric coupling characteristics and optimal weak magnetic detection capability under free boundary conditions and sandwich composite structure.However,in order to realize the suppression of environmental noise,the traditional integrated differential structure fails to make effective use of the 2-1 magnetoelectric composite structure,and the separated differential magnetoelectric coupling sensor is easy to be limited by the poor consistency of the preparation process and the weak symmetry of the sensor elements,resulting in the common mode suppression ratio of environmental noise can not meet the requirements.Therefore,in order to restrain the influence of environmental vibration and noise on the magnetoelectric sensor,a new differential structure design is proposed,which can not only ensure strong coupling and high sensitivity of the magnetoelectric coupling sensor,but also have the inhibition ability of common mode noise,so as to improve its environmental compatibility and platform adaptability.Under the background magnetic field of 1k Hz,the high magneto-electric conversion coefficient of 32V/cm/Oe is achieved,which doubles the sensitivity of the traditional 2-1 magneto electric sensor.The output signal of the single-phase sensor arm is separated and compared with the integrated vibration suppression sensor,their vibration response is calculated,and the structure principle is explained theoretically.Then through the experiment,it can be proved that the proposed integrated vibration suppression sensor structure can not only achieve noise suppression effect of 9 d B under the premise of amplifying the magnetic field response,but also achieve certain background noise suppression effect,and the detection limit can reach 1 n T in noisy indoor environment.Finally,a differential amplifying and filtering circuit for the integrated vibration suppression sensor is designed and prepared.The two magnetic field signals filtered by power frequency interference are different-amplified and outputed,which will facilitate the subsequent overall packaging and realize the integration and miniaturization of the sensor and its power circuit.