Ferrite losses of cores with square wave voltage and DC bias

Abstract

Ferrite material properties may vary depending on the grade and manufacturer. Moreover, there are differences between batches and also the production process may change in time. The same material grade may have improved or reduced performance depending on the year of production. In loss critical applications it is good to be able to test the losses on real cores. The usual voltage waveforms in power applications are closer to square wave than to sine wave. The DC bias can have a significant influence on the ferrite losses, so it is good to check this sensitivity. Losses were measured at frequencies of 20 kHz, 100 kHz and 500 kHz on 3F3 material