Design and Development of a Coaxial Integrated Triaxial Fluxgate Sensor

Triaxial fluxgate sensors are widely used in vector magnetic measurement due to their excellent robustness and high resolution. Conventionally, they are assembled from three orthogonally placed single-axis fluxgates. However, the non-coincidence of the three single-axis fluxgate axis center points results in sensitive area non-uniformity of each axis and large crosstalk. To solve the problem of sensitive area non-uniformity and improve the accuracy of triaxial fluxgate in vector magnetic measurement, the impact of the center point position of a triaxial fluxgate on magnetic field measurement is investigated through finite element analysis. A coaxial integrated triaxial fluxgate sensor probe and its supporting circuits are proposed and fabricated. In addition, the geomagnetic field at three locations is measured by the proposed coaxial integrated triaxial fluxgate and the orthogonally placed single-axis fluxgates with equivalent specifications. The experiments show that as the distance among the axis center points of the three axes of the probe increases, the measured total magnetic flux density shows a trend of increasing first and then decreasing. The total magnetic flux density measurement error of the designed coaxial probe at all three locations is less than $3~\mu $ T, which is better than the assembled triaxial fluxgate probe. The proposed coaxial triaxial fluxgate effectively overcomes the problems of large crosstalk and measurement point deviation caused by the non-uniform axis center points of traditional triaxial fluxgates.