Bp 463 en

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Excitation unit for orthogonal fluxgate with dc bias flipping

Author: Coroli Iurie

Bakalářské práce 2016

Stáhnout práci v PDF

The goal of this bachelor thesis is to develop a system for suppression of the offset and its temperature drift in an orthogonal fluxgate in fundamental mode. The offset is gen-erally high, unstable and has a large thermal drift, which results in a large low-frequency noise. We propose a system that periodically flips the polarity of both DC and AC excitation currents to overcome this issue. The polarity flipping however introduces transients and additional noise at larger frequency; we overcome this issue by digital signal processing, excluding the first periods after polarity flipping from integration. We managed to achieve thermal offset variation of about 0.015 nT/°C with tolerable increase of the noise floor at high frequency. The achieved offset stability and low noise floor are comparable to top class available fluxgates. Such combination of characteris-tics has never been achieved on a cheap fluxgate sensor so far. Moreover, we have low power consumption because we use low excitation current below 100 mA and there is no need for expensive electronics.

Bp 2016 coroli iurie.pdf
P 2016 coroli iurie.pdf