Demans for the dc current sensor have been increasing recently. We have developed a hysteresis free current sensor based on a magnetic bridge by using a magnetic fluid as a core material which is superparamagnetic and has on magnetic hysteresis. In the experiment, the core size is 42mm in outer diameter, 28mm in inner diameter, 3.5mm in height. The sensor gets saturated at +-200A input current, but hysteresis was not observed in the whole measurement range. In the measurement range of +-20A, the sensitivity was 0.603mV/A, the linearity error was +-0.7%, and the temperature error characteristic was -0.2%/degree C at from 0degree C to 30degree C. This hysteresis free current sensor would be useful in energe efficient power systems for accurate current monitoring, especially dc power distribution systems.
[ FULL TEXT (pdf) ]