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Influences on the Detection Probability of Ferromagnetic Objects

Authors:
Lukas Heindler
Ruben Piepgras
Bernhard G. Zagar

Keywords: magnetic field, Hall sensor, remanence, magnetic disturbances

Abstract:
The detection of small masses of ferromagnetic ma- terials within an existing magnetic circuit can be very challenging. It is particularly difficult if the ferromagnetic material is only coupled loosely via comparably large air gaps while the rest of the circuit is ferromagnetic as well as a good electrical conductor. The problem is further aggravated by the fact that the mass can exhibit a substantial remanence of unknown strength and polarity. In principle, the influence of remanence would be suppressed using an AC excitation of the readout circuit. However, this would excite very strong eddy currents in any conductor within and in close proximity to the sensing device. Thus, even non-magnetic metallic components would cause a non-zero measurement reading. Therefore, we optimized a DC magnetic circuit that allows the detection of ferromagnetic materials. In our use case, we concentrated on cylindrical objects separated from the sensor by an air gap of up to 5 cm.

Pages: 35 to 40

Copyright: Copyright (c) IARIA, 2021

Publication date: November 14, 2021

Published in: conference

ISSN: 2308-3514

ISBN: 978-1-61208-918-8

Location: Athens, Greece

Dates: from November 14, 2021 to November 18, 2021