Interference‐rejecting current measurement method with tunnel magnetoresistive magnetic sensor array

Abstract

Innovative methods for wide range measurement of electric current remains an active research problem in modern power systems. Conventional methods based on magnetic field readouts have realized non‐contact current measurement by interpreting magnetic flux density into electric current, such as Hall effect and Rogowski Coil arrangement. TMR magnetic sensor has spread its application for current measurement due to its miniaturization, low cost, high response frequency and high sensitivity. However, due to the superposition of unwanted magnetic field, the magnetic fieldunder measurement is strongly affected. In this paper, a four‐sensor array design is proposed to solve this problem. Transcendental equations, which can not only calculate the current under measurement but also the interference current at random places, are constructed. Numerical simulations, finite element analysis (FEA) of the field and laboratory experiments were performed to verify the proposed method. It is shown that when targeted current is 100 A and interference is 820 A, the largest simulated error is 3.92 × 10 −10 ; when targeted current is 100 A and interference is 1000 A, error with FEA is 2.3796%, when targeted current and interference are both 500 A, experimental error is 4.14%. This verifies the effectiveness of the proposed method.