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A Neel Effect® current sensor featuring a double toroidal core is proposed. The measurement relies on the application of a harmonic excitation to the magnetic core and on the sensing of the magnetic flux density variations in the presence of a current to measure. The principle of a device designed so as to perform both those operations by means of the same winding is presented and validated experimentally. The measurement of DC currents is carried out over the [2200-200 A] range under different excitation conditions.
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Introduction: There exist many current sensor technologies such as shunt, Hall current sensors, fluxgates, current transformers, Rogowski coils etc. [1, 2]. They differentiate from each other by their ability to measure AC or DC signals and by their performances in terms of dynamic range, sensitivity, accuracy, size, flexibility, cost etc. Neel Effect current sensors which have recently been proposed [3, 4], rely on a principle almost similar to that of a fluxgate. Their originality lies in the characteristics of the magnetic transducer, the nonlinearity behaviour without saturation of which enables the measurement of high currents to be performed. Sensors based on the Neel Effect principle are being developed using superparamagnetic (SPM) nanostructured materials. Thus, Neel Effect sensors belong to the magnetic field sensors category. On the one hand, a harmonic magnetic field excitation is applied to the transducer via a winding fed by a sinusoidal current and on the other hand, the electromotive force (EMF) due to the magnetic flux density variations is sensed, also by a winding. In the presence of a current to measure, assumed to be continuous or slowly variable with respect to the excitation, a magnetic bias point is superposed to the magnetic excitation of the magnetic core, which results in a modification of the sensed EMF. The measurement of the EMF, and in particular that of the component at the second-order harmonic of the excitation frequency, enables the current to be determined [4]....