A Method for the Calculation of an Apparent Time Invarying Inductance for an Iron Core Inductor

A method for measurement of the instantaneous inductance L(t) of an iron core inductor is presented as a function of the inductor current i, the rate of change di/dt of this current, and the past history of the iron core at that moment. The inductance of a filter inductor is shown as a function of unidirectional continuous and discontinous currents. The concept of an equivalent time invarying inductance Leq is formulated for the purpose of piecewise linear time-domain analysis of switching networks, and a method for its calculation is indicated. The usefulness of this new tool of analysis is confirmed by agreement of calculated and experimentally obtained data.