Excitation circuit for fluxgate sensor using saturable inductor

Abstract

Traditional excitation circuits for fluxgate sensors consist of a lossy resistor or a bulky inductor (operated in non-saturated mode), whose function is to limit the excitation current. As a result, a high voltage source is required to provide sufficient excitation current to the sensor. For these reasons, traditional excitation circuits are unsuitable for portable battery operated devices that use fluxgate sensors. In order to reduce the circuit size and operating voltage in such applications, the use of a saturable inductor is proposed in this paper. Practical methods for choosing suitable circuit components are described to ensure that the circuit operates under optimum conditions. Experimental results illustrate a good linear relationship between the second harmonic voltage and the measured current for a fluxgate dc current sensor using the proposed excitation circuit. © 2004 Elsevier B.V. All rights reserved.