A Contactless Current Sensor Based on TMR Chips

Inexpensive, nonintrusive, and easy-installation current sensors are of great help in the economical and reliable operation of power systems. In this paper, a novel contactless current sensor with small size, ultra-micro power consumption, and self-power capability is proposed based on tunnel magnetoresistance (TMR). For measuring arbitrary line currents under an interference magnetic field, the single-axis TMR chips array and anti-interference method are introduced. Then, the designs of software and hardware are given for ultra-low power consumption and self-power. The experimental results showed that the measuring range of the current sensor is from 0A~1500A, and the error is less than 0.6% when the measured current is over 150 A.