Packaged current-sensing device with self-biased magnetoelectric laminate for low-frequency weak-current detection

A packaged current sensor consisting of a SmFe₂/PZT/SmFe₂ self-biased magnetoelectric (ME) laminate and a Fe_73.5Cu₁Nb₃Si_13.5B₉ nanocrystalline flux concentrator for weak-current detection at the power-line frequency is fabricated and characterized. The giant magnetostrictive material of the SmFe₂ plate with its large anisotropic constant provides a huge internal anisotropic field to bias the ME transducer in a closed magnetic loop. Consequently, the additional magnetomotive force induced by the internal field and the corresponding increased effective permeability contribute to an improvement in sensitivity. Experimental results demonstrate that the presented sensor has a higher sensitivity of 152 mV A⁻¹ at 50 Hz with a slight nonlinearity of ∼0.01% FS and matches well with the predicted value. This current-sensing device exhibits approximately 2.3 times higher sensitivity than does conventional ME composite with PZT and Terfenol-D plates serving as the key sensitive component. In addition, the packaged sensor is evaluated for a long period of 72 h to determine stability over time, and the results are analyzed by means of a mathematical statistics method; favorable stability with an uncertainty of 0.5 μV is obtained in continuous 1 h testing. These results represent a significant advancement in the development of promising applications of tri-layer self-biased ME laminate for monitoring power-line electric cords. (paper)