Amorphous Magnetic Cores For High Frequency Electronics

Amorphous magnetic cores allow smaller, lighter and more energy efficient designs in many high frequency applications for Invertors, UPS, ASD(Adjustable speed drives), and Power supplies (SMPS). Amorphous metals are produced in using a rapid solidification technology where molten metal is cast into thin solid ribbons by cooling at a rate of one million�C/second. Amorphous magnetic metal has high permeability due to no crystalline magnetic anisotropy.

Amorphous magnetic cores have superior magnetic characteristics, such as lower core loss, when compared with conventional crystalline magnetic materials. These cores can offer superior design alternative when uses as the core material in the following components:

Where typical ferrite cores can only operate up to a flux saturation level (B_sat) of 0.49 Tesla, amorphous metal cores can be operated at 1.56 Tesla. Combined with operating at permeability similar to high-end ferrites and the flexibility of manufacturing large cores sizes these cores can be an ideal solution for many of these components.

Nanocrystalline amorphous metal offers size, core and labor savings for various EMC applications.

MICROLITE 100 m Cores vs. The Competition  -  Properties

This comparison was done using 2500 perm ferrite and core loss comparison performed at 100 kHz and 1 kG _BAC

To choose the best core for your design down load the PFC calculator:

Executable | Zip file

• Data sheet for ordering: (link: Core Specifications for Ordering)
• PFC Design benefits: (link: Product Overview (PDF)159k )
• Technical data sheet: (link: Technical Bulletin (PDF) 104k)

Three phase designs can be done with standard single-phase cores or a custom three-phase core can be constructed in a two-piece set as shown below:

Amorphous metal C-cores allow for operation at higher frequencies at the same flux level. Where traditional steel cores need to operate at increasingly lower flux densities as the frequency increases. In order to compensate for running at lower flux densities significantly more material is needed. Even with additional material higher temperatures still occur. Another contributor to lowering losses is the I²R of the winding. A physically smaller amorphous core reduces your mean length per turn, hence your I²R copper losses are lower and copper costs are lower.

For higher current applications these cores open up the new options for the conductor winding process that is not easily achievable for toroidally constructed cores:

• Copper foil
• Large gauge square conductors
• Edge or disc winding.

In each of the above options, the winding can be accomplished on a separate mandrel and assembled onto the C-core after the winding process. Litz is wire commonly used for high current/high frequency designs. However, terminating litz wire for these applications can be expensive. An alternative to consider is disc or edge winding. This involves winding a rectangular wire that has a relatively high aspect ratio on its edge The quasi-planar structure reduces the skin effect, but not as great as using litz wire although greater than can be realized with similar magnet wire or copper foil. Other advantages are: lower copper loss, reduced DCR, smaller size, improved heat dissipation.

Higher wattage switching devices allowing operating frequencies of 10 and 20kHz are now becoming cost effective for the high power designer. In the past traditional EI and UI laminated inductors using 3% Ni, silicon grain oriented steel could be used with little problem. 3 percent nickel, silicon grain oriented steel appears to be dead above 1kHz. Special design considerations that take into account the lower flux densities at these frequencies allow this material to be pushed beyond its normal intended application. This however can result higher temperatures and much larger core sizes than with a comparable amorphous core design. These are summarized in the below chart:

This design assumes 50% permeability with 50 Oe of bias, 2500 perm ferrite was used for comparison and core determined at 20 kHz and 2 kg B_AC

When comparing Iron Powder to Amorphous core. The Amorphous core will tend to be less expensive, and have lower losses, smaller physical size, better heat dissipation, and are mechanically rugged

To choose the best core for your design, download following calculators:

• Data sheet for ordering: (link: Core Specifications for Ordering)
• PFC Design with C-cores (link: PFC Application Guide PDF Format 828k )
• Technical data sheet:   (link: Technical Bulletin PDF Format 305k)

For larger kilowatt power supplies,. High frequency transformers using these C-core offer higher saturation induction of 1.56 Tesla and lower losses allowing for:

• higher efficiency
• lower transformer weight
• reduced transformer volume

We produce rectangular shapes of amorphous metal cores by stacking layers of laminations made from amorphous metal ribbon. An adhesive rated for a continuous operating temperature of 155°C holds the laminations together.

These forms offer a unique combination of high saturation induction (1.56 T), high permeability and low core loss and can be configured into various shapes, allowing for one large gap to be distubuted across several smaller gaps, reducing fringing flux, and core loss.

Hybrids and be designed using c-core sections with corresponding bricks for unique shapes

Applications: Medium Frequency and High Power Inverters

MicroLite® Toroidal Choke Cores from Metglas® are manufactured with iron-based Metglas® amorphous Alloy-SA1. They offer a unique combination of high saturation induction, high permabiliity and the lowest core loss available for high frequency choke cores allowing the use of significantly smaller sizes than possible with conventional materials.

Applications:
dc Output Inductors; Flyback Transformers; Differential Mode in Chokes; PFC Boost Chokes - Continuous Mode.

MICROLITE XP products are made of amorphous alloys, which are non-crystalline in nature. Metglas� MICROLITE XP cores operate cooler and have lower core losses than cores made of conventional crystalline materials such as powdered iron, ferrite or sendust. MICROLITE XP's energy-efficient properties reduce the size of powder sources for demanding applications in the electronics industry

Applications:
Differential Input Inductors, PFC Inductors, Flyback transformers, and VRM Inductors.

MagnaPerm� High Permeability Cores are manufactured with cobalt-based Metglas amorphous alloy 2714AF for high frequency applications. Theses flat loop toroidalcores offer a unique combiation of ultra-high permeability, high saturation flux density and extremely low core loss for electronic component designers.

Applications:
EMI Common Mode Filtering; Telecommunications and Data Communications Interface Transformers; High Accuracy Current and Pulse Transformer Ground Fault Protection Devices.

Metglas® Square Loop Cores manufactured with cobalt-based Metglas® amorphous Alloy 2714A allow the design of mag amps that can operate at higher frequencies than previously possible. Their combination of magnetic properties enable mag amps to provide unparalleled precision and efficiency in output regulation.

Applications:
Saturable Reactors; Magnetic Amplifiers.

Nanocrystalline amorphous metal is produced by rapid quenching a molten alloy to produce a amorphous metal and then heat treating this alloy at higher than its crystallization temperature The alloy forms Nanocrystalline grain size of approximately 10 nm in the amorphous metal.

Our NANO amorphous tape-wound cores are used in (SMPS) Switched-Mode Power Supplies, Frequency Inverters, ASD and UPS and other applications for effective noise suppression caused by rapid changes in current. The high pulse permeability of these cores allow excellent performance in the suppression of reverse recovery current from the diode and ringing or surge current from switching circuit. The Surge Absorber Cores are normally used as single-turn choke or with very few turns

The saturation magnetic flux density is twice as high as that of Co-based amorphous metal and three times higher than that of Ni-Zn ferrite. The pulse permeability and the core loss are comparable to Co-based amorphous metal. As a result, a small core made of this material offers higher performance in suppression of surge current and voltage.

Are used for medium and large power and are toroidally wound cores which show excellent performance for the suppression of various kinds of current or voltage surge, such as a surge from a switching diode.

Core range in size from outside diameters of 11 to 38mm and inside diameters of 4 to 22mm.

For several years now, electronic watt-hour meters have more and more replaced the electromechanical Ferraris counters in the industrial world. Since their advantages are self-evident, it is now foreseeable, that domestic counters will also be substituted by electronic versions within the next decade.

The key component of an electronic watt-hour meter is a high-precision current transformer (CT) which isolates the whole device from the mains potential and provides the signal to be counted. By making use of modern high permeability materials like crystalline 80% NiFe of permalloy type (VACOPERM), Fe-based nano-crystalline VITROPERM or Co-based amorphous alloys (VITROVAC), the CT meets the requirements of phase and amplitude-error and linearity according the international meter standards ( e.g. IEC 61036, ANSI C12.xx) with and without DC tolerance in a very easy and economic way. Design support can be given with recommendations for core material, core size, number of