| With the development of intelligent power system,the demand for global monitoring of power grid,operation tracking of power related equipments and accurate positioning of fault areas has become increasingly obvious in recent years.These demands undoubtedly need to be solved by intelligent means,and the development of digital information sensing technology and the construction of advanced communication network are the key to breaking through the intellectualization.In the actual detection process,the traditional sensors in the power grid often expose some shortcomings: The electromagnetic current transformer with a wide range of applications often has magnetic saturation in the core magnetic circuit during long-term operation,resulting in current waveform distortion;The Hall sensor and electronic current transformer can not work without the continuous supply of external power supply;The manufacturing cost of magnetostrictive/piezoelectric sensor is very high,which will inevitably have a certain impact on its popularization.Combined with the above practical needs,this paper focuses on a layered magnetoelectric composite（copper electrode/piezoelectric ceramic PZT/copper electrode）to explore its magnetoelectric coupling effect under the action of external magnetic fields,so as to provide a strong core material for the research and development of new magnetoelectric sensors.Based on the charge measurement method under short circuit condition,a magnetoelectric energy exchange test system is designed and built to analyze the magnetoelectric coupling characteristics of composites.In order to obtain the most obvious magnetoelectric response,the resonant frequency of the experimental device is first measured.Then,the composition of the output voltage of the magnetoelectric energy exchange system is analyzed through experiments,and the waveform and phase of its input and output signals are studied.It is fully confirmed that the magnetoelectric voltage generated by the proposed composite comes from the product effect of the ampere force effect generated by the induced eddy current in the copper electrode and the piezoelectric effect of the piezoelectric ceramic itself.In addition,by testing the changes of system magnetoelectric voltage under different magnetic fields,it can be found that there is a good linear relationship between AC and DC magnetic fields and magnetoelectric voltage.In order to verify the reliability of the magnetoelectric system,the accuracy of the measurement results and the magnetic field detection limit are calculated,and finally a higher magnetoelectric voltage coefficient is obtained.At the same time,by considering the influence of variables such as magnetic field,eddy current and Ampere force,combined with the mechanical equation and the eigen equation of piezoelectric ceramics,the theoretical model of electromechanical coupling is established,and the theoretical modeling of magnetic force electric energy conversion of the whole system is realized,which provides theoretical support for the analysis of subsequent experimental results.The experimental results are highly consistent with the theoretical results,which proves that the proposed layered composites have considerable magnetoelectric effect.The good linear relationship between input and output signals also proves the practicability and reliability of the magnetoelectric material in DC/AC magnetic field detection.Because the magnetoelectric material does not need magnetostrictive phase and additional power supply,and has the advantages of simple structure,high magnetoelectric conversion efficiency and linear response measurement,it is expected to have a good application prospect in smart grid on-line monitoring and electrical equipment health tracking. |
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