A New Compact Fluxgate Current Sensor for AC and DC Application

This paper presents a compact current sensor for the measurement of ac and dc. The sensor consists of two toroidal magnetic cores. One core works in fluxgate principle to measure dc and low-frequency ac, and the other one is used as a current transformer for higher frequency application. The closed-loop configuration with a magnetic core and feedback winding in the sensor improved the sensitivity of the sensor, eliminated the offset and drift related to temperature, and greatly reduced the error caused by magnetic hysteresis phenomenon. It can measure currents up to 20 A, has an accuracy of 0.7% and $\sim 30$ -kHz bandwidth.