Vector closed-loop compensation type triaxial magnetic field sensor probe based on Helmholtz coils

Abstract

The invention relates to a vector closed-loop compensation type triaxial magnetic field sensor probe based on Helmholtz coils, which comprises a sensitive element, a feedback element, signal conditioning circuits, an excitation circuit and a V / I conversion circuit. The sensitive element comprises three same magneto-sensing sensors, namely an X-axis magneto-sensing sensor, a Y-axis magneto-sensingsensor and a Z-axis magneto-sensing sensor; the feedback element is a three-dimensional Helmholtz coil structure which consists of three pairs of Helmholtz coils which are orthogonal to each other, and the three pairs of Helmholtz coils respectively correspond to the three magneto-sensing sensors; the signal output ends of the three magneto-sensing sensors are respectively connected with three signal conditioning circuits which are connected with the excitation circuit, the output ends of the signal conditioning circuits are respectively converted by the V / I conversion circuit and then connected to the lead-out wires of three pairs of Helmholtz coils of the three-dimensional Helmholtz coil structure to form a closed loop. The probe can reduce the cross influence to the greatest extent andimprove the accuracy of the sensor.

Description

technical field [0001] The invention relates to the technical field of magnetic field measurement, in particular to a vector closed-loop compensation type three-axis magnetic field sensor probe based on a Helmholtz coil. Background technique [0002] The magnetic field is a vector, which has both magnitude and direction properties. Its measuring instruments are divided into two categories: scalar measurement and vector measurement. For the measurement of weak magnetic fields, commonly used high-precision and high-sensitivity scalar measuring instruments include proton magnetometers, optical pump magnetometers, atomic magnetometers, etc. These instruments have been widely used in the fields of space, ocean, geological exploration, and biomedical research. . However, scalar measurement can only obtain the magnitude of the magnetic field and loses its directional properties, so it has certain limitations in application fields such as geomagnetic navigation, unexploded ordnance...

AI Technical Summary

Problems solved by technology

However, although the use of current feedback can improve the performance of the sensor in the direction of the axis to be measured, there are the following problems: First, because the orthogonality between the three axes of X, Y, and Z is difficult to reach the standard 90°, so one of the axes Although the magnetic field generated by the feedback coil can offset its own magnetic field in this direction, it will also generate additional magnetic fields on the other two axes. Second, the solenoid structure formed by the feedback coil will also generate a magnetic field in the external space. As far as these two additional magnetic fields are treated equally with the external magnetic field to be measured, the magnetic field value obtained during measurement is the vector sum of the two magnetic fields, which is due to the cross-axis effect generated by the feedback current; in addition, in the closed-loop feedback In the circuit, the PCB onboard wires, the connecting wires between the circuit board and the feedback coil will also generate interference magnetic fields and affect the measurement. For example, when a current of 10mA passes through the DC wire, a 200nT magnetic field will be generated at 1cm around the wire

From the analysis of the above principles, it can be concluded that although the software compensation method can weaken the cross-axis effect, the operation process is complicated and the calibration process is extremely time-consuming; in addition, due to individual differences in sensors, each sensor needs to be calibrated once. suitable for mass production

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