Author(s)

Aktham Asfour, Jean-Paul Yonnet, Manel Zidi

Laboratoire de Génie Electrique de Grenoble (G2E-Lab), Institut Polytechnique de Grenoble, ENSE3, Saint Martin d’Hères, France.

The design and performances of a high dynamic range DC-AC current sensor utilizing Giant Magneto-Impedance (GMI) are presented. The sensor is based on a GMI element with negative feedback. The sensing element is a 30 μm diameter GMI Co-based amorphous wire. It is curled to a toroidal core of 2 cm diameter. A bias magnetic field of about 650 A/m is applied to the GMI element to obtain an asymmetric GMI effect. A strong negative feedback is introduced to ensure linearity in a wide dynamic range. Analog conditioning electronics was fully developed. This includes a square wave oscillator based on an inverter trigger; a peak detector and a high gain amplifier with zero adjust. The GMI element is driven at a 3 MHz frequency and 5 mA peak-to-peak current. The closed-loop operations are investigated and the performances of the sensor are presented. DC current measurements are performed. The sensor exhibits good sensitivity and very good linearity, free from hysteresis, in a wide dynamic range of ±40 A. The sensitivity is about 0.24 V/A and the linearity error is about 0.02% of the full scale (FS). The hysteresis error is smaller than the measurement accuracy. AC current measurements using the developed sensor have also been successfully achieved. The sensor bandwidth in closed-loop was about 1.7 kHz.

GMI; Current Sensor; Negative Feedback; DC-AC Current Measurements

A. Asfour, J. Yonnet and M. Zidi, "A High Dynamic Range GMI Current Sensor," Journal of Sensor Technology, Vol. 2 No. 4, 2012, pp. 165-171. doi: 10.4236/jst.2012.24023.