Tunnel Magnetoresistance-Based Noncontact Current Sensing and Measurement Method

Abstract

The dynamic characteristics of power systems have become increasingly complex with the growing application of power electronics equipment. A high level of real-time monitoring is now required to provide a database for system stability and safety control. Therefore, flexible and accurate sensor technology is crucial. In this article, a noncontact current sensing method is proposed using tunnel magnetoresistance (TMR) technology. Based on the introduction of TMR chip characteristics, the sensing law of a TMR chip surrounding a current-carrying wire is revealed. An arrangement of four TMR chips is then proposed to reflect the magnetic field intensity around a current-carrying wire. A TMR chip array-based noncontact current sensing technique is presented for use as a real set-and-use current sensing method. The convenience of the proposed method is superior to traditional current sensors because the wire does not need to be surrounded by a magnetic ring or coil. A method for location detection is presented to avoid iterating for every sample, which significantly reduces the computation burden. Simulations are then carried out to demonstrate the effectiveness of the proposed method. A current sensor prototype based on a printed circuit board (PCB) is developed, and its practicality is proven by experiments. Test results show that the prototype can meet the requirements of phasor measurement unit (PMU) standards, indicating that the proposed current sensing method is practical and can be applied in M-class and P-class PMUs for current sensing.