Ferrite Core Transformers: Types and Benefits
What are Ferrite Core Transformers? Transformers made out of ferrite core, having their windings made from ferrites, the non-conductive, ceramic, ferromagnetic compounds, are known as ferrite core transformers. The composition of ferrite cores in transformers is chiefly iron oxides, combined with nickel, zinc and manganese compounds. These compounds are characterized by low coercivity and therefore, are also known as soft ferrites.
Ferrite Core Transformers: Types and Benefits Transformers are driven by the flux linkage between primary, secondary and tertiary windings. For maximum performance, the transformer provides one low reluctance magnetic path, usually in the core. Here are considerations on how different materials are used for different types of ferrite core transformers.
Purpose of Ferrites Core Ferrites are made of ceramic compounds and act as insulators in transformers. Materials that comprise ferrites include iron oxides integrated with zinc, nickel and manganese compounds. A major advantage to a ferrite core is its high resistance to high current. It also provides low eddy current losses over many frequencies. Its high permeability adds to its ideal combination for use in high frequency transformers and adjustable inductors. In fact, the high magnetic permeability along with with a low electrical conductivity of ferrites helps in the prevention of eddy currents.
Types of Ferrite Core Transformers
Manganese Zinc Ferrite (MnZn) - useful for inductors up to 70 MHz
Nickel Zinc Ferrite (NiZn) - Higher resistivity than MnZn, useful when frequency range is from 2MHz to MHz in the several hundreds and ideal for inductors over 70 MHz
Temperature and permeability play huge roles in ferrite core selection, since ferrite materials begin to lose magnetic capabilities under 500 degrees Celsius. Ferrites are also classified by shapes such as:
E, I Cores - easy to construct with simple bobbin winding, making them useful for power and telecom inductors, along with broadband, converter and inverter transformers
ETD Cores - center post has minimal winding resistance, ideal for power transformers and inductors
EFD Cores - made with cross-sectional areas provide utility for compact transformers
EER Cores - based on a round center post, providing a shorter winding
Another option is to create a custom transformer to suit the needs of a specific application. Keep in mind that customization may provide greater performance at a higher upfront cost, but possible better cost efficiency in the long run.
Conclusion Ferrites play a major role in how inductors operate based on the materials from which they are made. Iron oxides combined with other elements form the basis of a ferrite, which is used as the magnetic core for a transformer. The performance of the application is often determined by the selection of ferrite materials.
