Development of a Small and Wide-Range Three-Phase Current Sensor Using a MI Element

摘要

This paper describes a three-phase electric current sensor, which implements compact size and wide measurement range, using the magneto-impedance (MI) sensor1). There were the following subjects in the conventional current sensor. A small current transformer has a narrow measurement range due to the magnetic saturation in the iron core. To reduce the influence of the magnetic saturation, an air gap is put in the core2). However, it is not suitable for measuring small current, because the sensitivity is decrease. While, the zero-flux-control3) is the other method to suppress the magnetic saturation. However, the power consumption increases as the measurement current increases, because the negative feedback current is necessary.