Research On Flexible Self-powered Magnetic Sensor Based On Magnetoelectric Transducer

As an important part of modern information technology,magnetic sensors are widely used in aerospace electronics,smart grid,biomedical and other fields.In recent years,with the rapid development of electronic skin,wearable devices and other fields,magnetic sensors with good flexibility have become a new research hotspot.Because the traditional magnetic sensor is not flexible,it has been difficult to adapt and meet the needs of measuring the diversity of the environment,so it is more important to carry out research on flexible magnetic sensors.Secondly,because in the current wireless sensor network,the sensor node is usually powered by a battery,which makes it poor in endurance and high maintenance cost,and also pollutes the environment.To a certain extent,it hinders the application development of wireless sensor networks.Therefore,it is of great research value and academic significance to carry out research on new flexible self-powered magnetic sensors.According to different detection principles,magnetic sensors can be divided into several categories,such as Hall,Giant magnetoresistance and Magnetoelectric composite.Among them,the sensor based on magnetoelectric transducer has great development potential in the field of magnetic sensors because of its advantages of simple preparation,high sensitivity and magnetoelectric conversion efficiency.Under the supported of the National Natural Science Foundation of China?No.51775070?,this thesis takes magnetoelectric transducers as the research object,and studies the magnetoelectric effect and sensing characteristics of magnetic sensors from theory and experiment.At the same time,a new self-powered magnetic sensor is designed in combination with the power management circuit.The collected magnetic field energy can be used to power low-power devices,and finally applied to industrial fields such as high-frequency power grids.The specific research of the thesis is as follows:?1?The types and performance parameters of magnetostrictive materials and piezoelectric materials were studied and analyzed.For the difference of magnetic/polarization direction,the output performance of magnetoelectric transducers under different working modes is compared.The equivalent output method is used to study the theoretical output expression of the transducer in the resonant and low-frequency states.The factors affecting the output of the transducer are summarized,which provides a theoretical basis for designing high-performance magnetoelectric transducers.?2?The effects of transducer size,applied bias magnetic field,excitation frequency and bending angle on its magnetoelectric output performance were studied.It is revealed that H_dc=5 Oe is the optimal bias magnetic field.At the same time,the larger the aspect ratio of the transducer,the better the output effect,and the maximum?_ME,r is240.42 V/cm·Oe;The transducer structure is optimized to provide good bending performance with high magnetoelectric output capability.?3?A sensing characteristic test system was built to study the sensing characteristics of PVDF/FeSiB magnetoelectric transducers for alternating magnetic field and static magnetic field.It is found that the transducer has good DC/AC sensing characteristics within a certain magnetic field,and the linearity can reach 0.382%and4.23%,respectively.The transducer's performance for weak magnetic fields,low frequency signals,and anisotropic magnetic field sensing is also studied.?4?The load output performance of the sensor was studied using three different rectifier circuits.The maximum output power obtained was 14.53?W,and the corresponding optimal load value was 70 k?.The effects of static magnetic field and dynamic magnetic field on the energy harvesting performance of the sensor are studied.The magnetic sensor parameters:sensitivity,hysteresis,reproducibility and resolution were studied separately.The results show that the minimum resolution is up to.The power management circuit is used to store the magnetic field energy collected by the sensor and used to supply power to the low-power wireless transceiver module.The sensor is finally applied to8.19?10^-8T?the current monitoring of the high frequency energized conductor.