Design Of Auto-compensation And Sensor Miniaturization For Fluxgate Magnetometer

Fluxgate magnetometer is a kind of vector magnetometer which has the ability of measuring the components of magnetic field directly. The fluxgate instrument is variometer based on magnetization non-linearity of "soft" magnetic material. With the developing of the technology of automatic magnetic data processing, fluxgate magnetometer is widely used in geomagnetic observation now.First of all, this paper introduced the working theory of three kinds of fluxgate magnetometer sensors: single core sensor, double core sensor and ring core sensor. Then the author discussed relations between noise and demagnetization coefficient, and relations between noise and dimension of fluxgate magnetometer sensors. Three kinds of common methods (called as tuning and magnifying method, short circuit method, apparent coercive field strength method) for fluxgate magnetometer signal detecting and their advantages and disadvantages are described in this paper.This paper proved the possibility of the miniaturization of fluxgate sensor by theoretic analyses. Relations between the Signal-to-Noise, sensibility, demagnetizing factor, output of fluxgate sensor with its diameter, thickness and turns of core are discussed in this paper. The author of this paper also concluded some basic principle for the designing of fluxgate sensor. The author designed and produced two dimension sensors to prove the possibility of the miniaturization of fluxgate sensor.Since the geomagnetic observation developing for the simplest, the highest degree of automation and digitalization, and the geomagnetic data requiring more integrality and continuity, the developing trend of geomagnetic instrument is the fully digitalization and automation. As a kind of variometer, fluxgate magnetometer should has high observation precision as well as long-term stability and favorable temperature features. The compensation technology is the key for the performance of fluxgate magnetometer. This paper made an introduction about the compensation principle of fluxgate instrument. Compared with the traditional compensation technology, the author of this paper brought forward a new idea to realize auto-compensation on basis of the auto-controlling theory. The related electro-circuit and controlling program for auto-compensation are introduced in this paper in detail. Experiments were made to test the stability and temperatures features and the results shows that the effect of auto-compensation is better than the traditional compensation method.