High-Efficiency Low-Loss Amorphous Iron Core for Transformers

What Is an Amorphous Iron Core?

An amorphous iron core is a soft magnetic component made from amorphous metal, a metallic glass produced by cooling molten alloy so fast that no crystalline structure can form. The molten metal is cast onto a rotating copper wheel and solidifies into ribbon at a cooling rate of about one million degrees Celsius per second. Because the atomic arrangement is random rather than crystalline, there are no grain boundaries to pin domain walls, which gives the material outstanding soft magnetic behavior.

Features of Amorphous Alloy Cores

Rapid solidification: ribbon is produced at a cooling rate of about 1,000,000 °C per second.

Non-crystalline structure: the absence of grain boundaries eliminates magnetic anisotropy and improves soft magnetic response.

High permeability: the material concentrates magnetic flux efficiently and reduces the magnetizing current.

Low core loss: losses are significantly lower than conventional silicon steel, cutting heat generation and raising efficiency.

High saturation flux density: amorphous cores operate at higher flux density than ferrite cores, enabling smaller and lighter designs.

Comparison with Silicon Steel and Ferrite

For distribution transformers, amorphous cores reduce no-load loss by roughly 60% to 80% compared with conventional silicon steel cores of the same rating, which is why grid operators adopt them in loss-reduction programs.

Applications

Power transformers: smaller, lighter and more energy-efficient distribution transformers.

Power electronics: high-power medium- and high-frequency transformers and switching power supplies.

Inductors: common-mode chokes, PFC boost inductors and filter reactors.

Other components: EMI suppression parts, magnetic amplifiers and pulse transformers.

Design Considerations

Amorphous ribbon is very thin, typically 20 to 30 µm, and hard, which raises punching difficulty and reduces the stacking factor that must be accounted for. The material is also magnetostrictive, so cores must be clamped and annealed properly to limit audible noise. When a transformer with an amorphous core is designed, the no-load current, inrush current and noise should be verified with the actual core lot, because small variations in annealing affect loss values. GNEE Electric supplies amorphous ring cores, C-cores and distribution transformer cores with measured loss data, tested in accordance with GB/T 19346.1 and IEC 60404-6.

FAQ

1. How is amorphous ribbon produced?

Molten alloy is ejected onto a rapidly rotating copper wheel and solidifies at about one million degrees Celsius per second into ribbon 20 to 30 µm thick, without forming a crystalline structure.

2. Why is amorphous core loss much lower than silicon steel?

The random atomic structure eliminates grain boundaries and reduces the energy needed to move magnetic domain walls, while the thin ribbon suppresses eddy currents. Both effects lower hysteresis and eddy-current losses.

3. Can amorphous cores replace ferrite cores at high frequency?

In many high-power designs yes, because amorphous material offers higher saturation flux density and permeability. Ferrite still wins at very high frequencies where its extremely low eddy-current loss and low cost matter more.

4. What is the typical thickness of amorphous ribbon?

Standard ribbon thickness is about 20 to 30 µm, roughly one-third the diameter of a human hair.

5. Which standards apply to amorphous core testing?

Loss and permeability measurements follow GB/T 19346.1 and IEC 60404-6; transformer application requirements follow the IEC 60076 series.