AMR current measurement device

Many devices for contactless current measurement employ a magnetic circuit (flux concentrator) formed by a ferromagnetic ring (or yoke) with the sensor (typically Hall element) placed in the air gap. Thus the impact of the ambient magnetic fields (i.e. other than caused by the measured cur-rent) is highly reduced and the sensitivity of the device is increased. However, the linearity of such measurement can be affected by the non-linear behavior of the magnetic material of the yoke. A device for the contactless current measurement with anisotropic magnetoresistive sensors (AMR) has been developed. As the AMRs are much more sensitive than classically used Hall sensors, no magnetic concentrator is needed. The realized device reaches so far the linearity error of +/- 0.05% in the current range of +/- 8 A, i.e. the absolute resolution is 4 mA. (C) 2007 Elsevier B.V. All rights reserved.