Estimating Inductances of Coils with Ferromagnetic Cores with a Data Acquisition System in a Noisy Environment

This paper deals with the experimental setup, methodology and original algorithms used for the estimation of inductance specific to coils with ferromagnetic cores during the transient process associated to the discharging of a capacitor in a series RLC circuit. A data acquisition system characterized by a sampling rate of 100 kHz for each of the employed channels (one for current and one for voltage) and a resolution of analog to digital conversion of 12 bits is used. Experimental data were acquired on a test stand in an industrial environment where significant electromagnetic noise pollutes the acquired signals. An original program was conceived for the preprocessing of acquired data. It performs the removing of fake spikes and eliminates the electromagnetic noise, computes the signal to noise ratios and allows the user to select variable coordinates for zooms by using the graphical interface in order to provide accurate estimations of the inductance in different moments. Two case studies are presented and discussed.