A Novel Tunneling Magnetoresistive Current Sensor Based on Reference Magnetic Field Source

Accuracy improvement of the current sensor is crucial in the electric power industry. In this letter, we present a novel nonintrusive current sensor, based on the tunneling magnetoresistance (TMR) chip, with the feature of simple, low cost, low power consumption, and high accuracy. A stable reference magnetic field, which is generated by the coil, is designed to be mixed with the primary current induced magnetic field and can be detected by the TMR chip simultaneously. An error compensation scheme was introduced based on the reference magnetic field and the error created by the hysteresis is effectively reduced. Experiments were made in which the hysteresis curve, the linearity, the error, and the stability of the sensor were tested. The results show that the errors of our sensor are below 1.46%, when increasing the primary current from 1 to 10 A, which is much less than the TMR chip.