Design Optimization of a Fluxgate Current Sensor With Low Interference

A new fluxgate current sensor is presented in this paper. The sensor consists of an additional magnetic toroidal core and an additional winding, aside from the elements in a traditional sensor. In addition, the exciting winding is wound along the circumference of the toroidal core to decouple the exciting magnetic field and the feedback magnetic field in order to reduce internal interference. With the additional core and the additional winding, the proposed current sensor can extend its bandwidth to medium- and high-frequency ac measurement. Another purpose of introducing the additional core is to concentrate on the exciting magnetic field and to reduce interference from external disturbances. A prototype of the proposed sensor was designed and tested. Test results show that the sensor is less affected by hysteresis effects and has a measurement error (precision) within 0.4% of the full scale, a 40-kHz small-signal bandwidth, remarkable sensitivity, and linearity in the measurement range up to 25 A.