A wide-range DC current sensing method based on disk-type magnetoelectric laminate composite and magnetic concentrator

Abstract

A DC current sensing method is developed by introducing the controllable sensitivity. The prototype sensor is implemented by inserting a transverse-transverse (T-T) mode disk-type magnetoelectric (ME) laminate into the air gap of a C-shaped ferrite magnetic concentrator to measure a wide range DC current. The equivalent circuit model of the ME laminate containing interface coupling factor, which physically reflects the strain transfer between the phases, has been further applied in DC current sensing under both low and resonant frequency excitation in this paper. The theoretical analysis results indicate that the DC current sensitivity is controllable by setting the quiescent operating point on the d31,m-Hbias curve of Terfenol-D and the excitation frequency of the ME laminate, respectively. Under 1 Oe AC magnetic field drive at 1 kHz, the DC current sensitivity dVac/dIdc of this DC current prototype sensor is 0.058 mV/A, equivalently 0.124 mV/Oe over the range of 0–500 A. Under resonant frequency AC magnetic drive, the current sensitivity dVac/dIdc = 2.38 mV/A, equivalently 5.12 mV/Oe over the same current range, considerably higher than that reported in previous DC ME sensor literatures. The experimental results provide a potential strategy for realizing wide-range DC current sensing in real applications. For lower current measurement, this ME based DC sensor should be operated under resonant excitation to obtain a high voltage output, while for higher current, it can be switched to be operated at a proper quiescent operating point under non-resonant frequency for an acceptable output.