Inductance Estimation Method for Inductors Used in DC-DC Power Electronic Converters: Theory and Application

The information of an inductor’s inductance is required for many applications of DC-DC converters, such as controller tuning, non-invasive current estimation, power sharing between different converters, etc. Alteration in operating conditions, such as temperature, aging, possible deformation in the inductor core, and path length of the printed circuit board affects the value of effective inductance. Change in the inductance changes the peak-to-peak current ripple of the inductor current, which affects the closed-loop system behavior of the dc-dc converter. On account of different converter-related constraints (like inaccessibility of measuring points, converter packaging, etc.) the value of the inductance can not be measured directly. An indirect method of estimation of inductance is one of the solutions to the above-mentioned problem. The inductance of the inductor in a dc-dc converter can be indirectly estimated by employing a series arrangement consisting of a switch and a predetermined resistance (meter resistance) value connected in parallel with the load. The theory of the inductance estimation method and its implementation aspects are presented in this paper. The theory of estimation has been validated using a non-invasive current estimator for a dc-dc boost converter.