Amorphous Block Cut Cores for Output Filter Reactors

An amorphous block cut core is a magnetic component made from a non-crystalline, iron-based metallic glass ribbon that is wound into a block and then cut into two halves to form a cut core. Because the material has very low core loss, high permeability, and good thermal stability, these cores are widely used in output filter reactors, inverters, and power supplies where efficiency and stable performance are critical.

What Is an Amorphous Block Cut Core?

Amorphous alloys are produced by rapid solidification: molten metal is cooled extremely quickly so that the atoms do not form a regular crystal lattice. The resulting ribbon has a disordered, glass-like structure with high electrical resistivity. For a block cut core, the ribbon is wound into a rectangular or block-shaped body, annealed to optimize magnetic properties, and then cut into two halves. The two-piece construction makes it easy to wind the coil before the core halves are reassembled, which is convenient for reactors and inductors.

Key Features

Low core loss: hysteresis and eddy current losses are significantly lower than in traditional silicon steel, improving efficiency and reducing heat.

High permeability: the core stores and transfers magnetic energy effectively, allowing a smaller core for the same inductance.

High saturation flux density: typical iron-based amorphous material reaches about 1.56 T, which supports compact reactor design.

High-frequency performance: losses remain low at switching frequencies, which is essential for power electronic devices.

Good mechanical properties: the core has high mechanical strength and can withstand vibration and mechanical stress.

Low temperature coefficient: magnetic properties remain stable over a wide temperature range.

Environmentally friendly: amorphous cores do not contain rare earth metals and are fully recyclable.

Why Amorphous Cores Are Used in Output Filter Reactors

An output filter reactor smooths the current waveform and limits voltage overshoot in a power supply. The core material must provide stable inductance over the operating current and temperature range while keeping losses low at the switching frequency. Amorphous material meets these requirements better than silicon steel at high frequency because its thin ribbon and high resistivity suppress eddy currents. Compared with ferrite, amorphous material offers a much higher saturation flux density, so the reactor cross-section can be smaller for the same current rating.

Typical Applications

Output filter reactors for switch-mode power supplies and uninterruptible power supplies.

Reactors in solar inverters and wind power converters.

Common mode chokes and differential mode inductors.

Energy-efficient distribution transformers in electric grids.

Filters and chokes in industrial drives and welding equipment.

Manufacturing and Quality Control

The production route includes ribbon slitting, core winding, annealing under a controlled atmosphere, impregnation or coating, cutting into halves, and final testing. Magnetic performance such as core loss and permeability is verified according to IEC 60404-6 methods for soft magnetic materials. Dimension and weight checks are performed on every batch to ensure consistency.

Ordering Information

Required inductance and operating frequency range.

Rated current and peak current, including overload conditions.

Core dimensions or available window area.

Operating temperature range and cooling conditions.

Whether a coated, taped, or cased finish is required.

Frequently Asked Questions

Q1. What is the difference between a block core and a cut core?

A block core is the wound, uncut body of ribbon material. A cut core is the same body sawn into two halves, which allows the coil to be wound around each leg before assembly. Cut cores are preferred for reactors where the winding must be replaced or the core is large.

Q2. Why is amorphous material better than silicon steel for high-frequency reactors?

Amorphous ribbon is very thin and has high electrical resistivity, so eddy current losses stay low at high frequency. Silicon steel suffers sharply increasing losses when the frequency rises above power frequency.

Q3. What is the typical saturation flux density of iron-based amorphous material?

Typical iron-based amorphous alloys have a saturation flux density of about 1.56 T, which is lower than grain-oriented silicon steel but much higher than ferrite.

Q4. Can amorphous cores operate at high ambient temperatures?

Yes. Amorphous material has a low temperature coefficient of magnetic properties and good thermal stability, which makes it suitable for enclosures with limited ventilation.

Q5. Are amorphous block cut cores available in custom dimensions?

Yes. The winding process can produce a wide range of cross-sections and window sizes. Customers provide the required core geometry or electrical specification and the core is built to order.

Q6. Do amorphous cores contain rare earth metals?

No. Iron-based amorphous alloys are composed of iron, silicon, boron and small additions, and do not contain rare earth elements, which supports environmental compliance.