What types of cores are used for transformers? What type for inductors?
07 May 2010
| Jason Hare
Desirable materials for transformer cores are those that have a high flux density and keep the temperature rise within desirable limits. High permeability materials are desirable to limit the exciting current (air gap minimized). For lower frequency applications (under 20 kHz), strip materials have the highest flux density; for higher frequency applications (above 20 kHz), ferrites are desirable because the materials are designed to have low core losses (lower heat rise) at these higher frequencies.
For inductors, cores that have discrete or distributed air gaps are desirable because they can maintain their constant permeability levels up to high DC or AC drive levels. Ferrites and strip wound cores can be gapped. Powder cores have a built-in distributed air gap.