A passive current sensor employing self-biased magnetoelectric transducer and high-permeability nanocrystalline flux concentrator

A passive current sensor, consisting of SmFe₂/PZT/SmFe₂ self-biased magnetoelectric (ME) composite and Fe_73.5Cu₁Nb₃Si_13.5B₉ nanocrystalline flux concentrator for weak current detection at power-line frequency, was fabricated and characterized. Giant magnetostrictive material of SmFe₂ plate with large anisotropic constant provides a huge internal anisotropic field to bias the ME transducer in closed magnetic loop. Consequently, the additional magnetomotive force induced by the internal field and the corresponding increased effective permeability contribute to the improvement of the 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 % full scale (FS) and matches well with the predicted value. This presented current-sensing device exhibits approximately 2.3 times higher sensitivity than that of conventional ME composite with [Pb(Zr_0.48,Ti_0.52)O₃] (PZT) and Terfenol-D plates serving as a key sensitive component. In addition, time stabilities of the presented sensor were evaluated for a long period of 72 h and analyzed through mathematical statistics method, and favorable stabilities with an uncertainty of 0.5 μV are obtained in continuous 1 h testing. These results provide a significant advancement toward promising application of the tri-layer self-biased ME laminate for power-line electric cords monitoring.