These chokes are used for energy storage in applications like switching power supplies and DC/DC converters. They usually consist of one conductor wounded around a metal powder core. As the inductivity decreases at increasing load current the operational mode is chosen at 60-75% of the induction without any load.
As the current polarity continuously changes, Eddy-currents are generated causing the coil to heat up. Because of that the current ripple should be limited and the exact specification of the core is to be determined by the switching frequency.