What is a Ferrite?
In the 1940s, a novel class of non-metallic magnetic material was created: ferrite. It’s a ferrimagnetic metal oxide. When it comes to electrical properties, ferrite has stronger dielectric qualities and far higher resistance than magnetic materials made of a single metal or alloy. High magnetic permeability at high frequencies is another way that ferrite’s magnetic characteristics are shown. Ferrite is now a commonly utilized non-metallic magnetic material in the high-frequency weak current field as a result.
High-Frequency Transformers and Ferrite Cores
In power supply applications demanding operation above 50 kHz, transformers become smaller and highly efficient. These transformers utilize cores made from powdered ferrites—an alloy of magnetic materials in fine powder form. The ferrite core is produced by firing the powder in a kiln with a ceramic filler, resulting in an insulating core composed of numerous small volumes of magnetic material. This composition minimizes core losses at high frequencies, making these cores suitable for inductors and transformers.
In typical applications, coils are wound on a bobbin, and the core, often shaped like two cups, surrounds and passes through the coil bobbin. This specific core geometry limits external fields. The mating surfaces of the core are meticulously machined and polished to eliminate gaps, crucial for achieving effective high permeability. Some core versions allow for the introduction of a precise air gap if necessary.
These ferrite cores find use in building inductors or transformers requiring DC ampere-turns. Gapped transformers with these cores can store energy, facilitating transfer to secondary circuits. This energy storage and transfer mechanism is fundamental to the design of switching regulators—a key aspect of modern power supply systems operating efficiently at higher frequencies.