PCB fluxgate current sensor with saturable inductor

This article describes the design and testing of a planar current fluxgate sensor prototype. The prototype is composed of a fluxgate current sensor totally embedded in printed circuit board combined with signal processing electronics. The fluxgate sensor excitation and pickup coils are implemented as racetrack shaped copper windings in the printed circuit board internal layers and they are surrounded by an electroplated magnetic core consisting of a thin film of nickel-iron alloy. The electronics provides excitation (including saturable inductor) of the fluxgate and signal processing (filtering and synchronous detection) of the pick-up signal. The prototype has been tested over a 2 A current range with sensitivity 28 V/A at 60 kHz. Excitation using a saturable inductor at 60 kHz has been used and 2 A peak-peak value of the excitation current was reached. We decreased consumption in the sensor from 2.6 W for sine-wave excitation to 0.7 W for excitation for saturable inductor.