Analytical and numerical analyses of a current sensor using non linear effects in a flexible magnetic transducer

Abstract

A theoretical study and a simulation method are proposed for superparamagnetic current sensors implementing a uniformly wound toroidal core topology. So as to be easy to implement, this sensor topology can be made flexible thanks to the use of a core made up of a superparamagnetic powder embedded in a flexible plastic matrix. The measurement of DC and AC currents is possible provided that a sinusoidal magnetic field excitation is applied to the superparamagnetic transducer. An analytical model is proposed for computing the sensor output signal and we demonstrate that when the detection of the component at the second order harmonic of the excitation frequency is used, the measurement is independent of the conductor position in a given current range. For simulating the dynamic response of the sensor, we propose to combine the analytical model, or a finite elements model, with a time-discretization method. Furthermore, simulations are carried out considering a ring shaped sensor and the real magnetization characteristics of a superparamagnetic material. Simulations are provided over the [-10kA 10kA] range and for various amplitudes of the excitation signal. The results obtained with the analytical model, which is computationally efficient, are within 4% to 12.7% from the numerical results.