Theoretical analysis of novel weak current sensor using FeCuNbSiB single nanocrystalline toroidal core and double-winding

Abstract

An Fe_73.5Cu₁Nb₃Si_13.5B₉ nanocrystalline toroidal core made by isothermal furnace annealing shows good thermal stability of magnetic properties and excellent soft magnetic properties due to the full release of the internal stresses of the core during the annealing process. Based on the feature of the magnetic core, a novel non-contact type weak current sensor adopting single nanocrystalline core and double-winding excited by multivibrator bridge is proposed. The measuring principles for static current are given in theory by an established mathematical model of the sensor. The theory is in good agreement with the experimental results and it indicated clearly the key factors affecting performance parameters for the sensor. The multivibrator bridge output signal was analyzed by Fourier transform. Furthermore, according to the theoretical results, the method to design the signal conditioning circuit was introduced.