Temperature Characteristics of a Fluxgate Current Sensor With Fe–Ni–Co Ring Core

In order to reduce the variations of sensitivity against temperature in practical fluxgate current sensors, we fabricated a fluxgate current sensor comprising a 20 μ-thick Fe15Ni46Co39 film, which had not only low coercivity but also high Curie temperature, electroplated on a Cu ring. It was confirmed that the sensitivity of the sensor with Fe15Ni46Co39 core was the same as that of the sensor with the Fe21Ni79 core by adjusting the exciting current. The Fe-Ni-Co-core-based sensor demonstrated small sensitivity variations of ~5% in a temperature range from -10 °C to 125 °C, whereas typical commercial sensors with a Co-based amorphous ribbon and a Fe-Ni-based sheet showed the sensitivity variations above 10%. The small fluctuation of sensitivity was considered to be attributed to the increase in the Curie temperature of the core material. It was clarified that the above-mentioned sensor consisted of Fe-Ni-Co core has high sensitivity together with high robustness against temperature.