A DC current sensor based on disk-type magnetoelectric laminate composite

Abstract

This paper describes the design and implementation of a new DC current sensor based on T-T mode disk-type magnetoelectric (ME) laminate composite, in which two layers of transversely magnetized magnetostrictive Terfenol-D and one layer of transversely polarized piezoelectric PZT are epoxy-bonded. Compared to traditional applications for AC magnetic or current sensing under constant DC magnetic field, we exploit DC current measurement of the ME laminate under constant AC magnetic field drive. A ferrite magnetic concentrator is applied to centralize magnetic flux. A pair of Nd-Fe-B magnets and the measured DC current Idc are used to provide the DC bias magnetic field for the ME composite. The DC current sensitivity calculation is performed on the base of equivalent circuit modeling and magnetic circuit analysis. The theoretical prediction and the experimental result are thoroughly compared. The difference between them is rectified by a correction factor. Under resonant AC drive, a stable induced voltage, more than 9 V, changes with the variation of the measured DC current Idc over the range of 0 ∼ 500 A, indicating that this sensor is applicable for DC current measurement. The DC current sensitivity over the range of 0 ∼ 500 A is 2.42 mV/A with 1 A AC current at the resonant frequency fr = 84.9 kHz. Several measures for enhancing the current sensitivity are also discussed in this paper.