Circular Array of Magnetic Sensors for Current Measurement: Analysis for Error Caused by Position of Conductor

Abstract

This paper analyzes the measurement error, caused by the position of the current-carrying conductor, of a circular array of magnetic sensors for current measurement. The circular array of magnetic sensors is an effective approach for AC or DC non-contact measurement, as it is low-cost, light-weight, has a large linear range, wide bandwidth, and low noise. Especially, it has been claimed that such structure has excellent reduction ability for errors caused by the position of the current-carrying conductor, crosstalk current interference, shape of the conduction cross-section, and the Earth’s magnetic field. However, the positions of the current-carrying conductor—including un-centeredness and un-perpendicularity—have not been analyzed in detail until now. In this paper, for the purpose of having minimum measurement error, a theoretical analysis has been proposed based on vector inner and exterior product. In the presented mathematical model of relative error, the un-center offset distance, the un-perpendicular angle, the radius of the circle, and the number of magnetic sensors are expressed in one equation. The comparison of the relative error caused by the position of the current-carrying conductor between four and eight sensors is conducted. Tunnel magnetoresistance (TMR) sensors are used in the experimental prototype to verify the mathematical model. The analysis results can be the reference to design the details of the circular array of magnetic sensors for current measurement in practical situations.

Tunneling Magnetoresistance DC Current Transformer for Ion Beam Diagnostics

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“…These sensors are based on the MR (Magnetoresistance) effect [ 11 , 12 , 13 ]. MR IC sensors are used for low magnetic field detection since their sensitivities are extremely high, but they saturate at low magnetic field levels compared to Hall sensors [ 4 , 11 , 12 , 13 ].…”

Rectangular Array Electric Current Transducer with Integrated Fluxgate Sensors

“…Circular sensor arrays are becoming popular due to their ability to suppress the influence of the conductor position and their good crossfield immunity [11]. These arrays are also based on the Ampere law and approximate the field integral by a sum of point sensor reading.…”

Modeling and Analyzing the Mutual Inductance of Rogowski Coils of Arbitrary Skeleton

“…The influence of the adjacent external conductors on the mutual inductance of the Rogowski coil is studied in [2], and when the primary conductors are straight and of the infinite length. Mengyuan Xu et al analyze the influence of the position of the primary conductors on the measurement errors of a circular array of the magnetic sensors for current measurement, and the straight and infinitely long primary conductors are located inside of the circular array of the magnetic sensors [22]. A special experiment is carried out to prove that the mutual inductance of PCB Rogowski coil is immune to the variation of the center of the plasma current in [4], and the formula of mutual inductance applies to the cases with the infinite-length primary conductors and the uniform magnetic field on the skeleton section.…”