Measurement and modeling of nonlinear magnetic core characteristics of a fluxgate direct current sensor for wide-range current monitoring

Fluxgate sensors are the most sensitive and reliable ones among different kinds of current sensors used in normal temperature. The sensor can measure a few milliamperes direct current. It is, therefore, applied in various small current measurements, especially for battery monitors. This paper proposes the way for extending current measurement range to a hundred amperes by using the information of secondary excitation frequency. The authors derive the dynamic circuit equations for analysing the frequency characteristics and a method for identify the nonlinear magnetic characteristics of the ferromagnetic core to the primary current.