Classification and application of magnetic cores in magnetic rings

Magnetic rings are composed of magnetic cores and plastic casings or insulating varnish. The magnetic core is used to increase the magnetic induction intensity of the electromagnet, while the plastic casing or insulating varnish serves to protect the magnetic core, prevent moisture, and enhance insulation. Magnetic rings are mainly classified by the type of magnetic core used, including ferrite magnetic rings, iron powder core magnetic rings, iron silicon aluminum magnetic rings, and amorphous magnetic rings.

Ferrite magnetic ring

Ferrite is a kind of material formed by sintering and polymerizing one or more metals such as magnesium, zinc and nickel with highly magnetic conductive materials at a high temperature of 2000℃. At low frequencies, the magnetic core exhibits a very low inductive impedance value, which does not affect the usefulness of data lines or signal lines

Signal transmission. At high frequencies, starting from around 10MHz, the impedance increases. The inductive reactance component remains very small, but the resistance component rapidly increases, forming a low-pass filter. Ferrite magnetic rings mainly include nickel-zinc ferrite and manganese-zinc ferrite magnetic rings, which are classified into low-permeability magnetic rings and high-permeability magnetic rings according to magnetic permeability. The magnetic permeability of manganese-zinc ferrite magnetic ring materials is generally above 1000, and they are called high-permeability magnetic rings. Manganese-zinc ferrite magnetic rings have a very high magnetic permeability and are usually used to wind common-mode inductors to suppress low-frequency common-mode conducted interference at power supply ports.

Nickel-zinc ferrite has a magnetic permeability between 100 and 1000 and is thus called a low-permeability ring. It is generally used for various types of cables such as power cords, HDMI cables, USB cables, etc.

Iron powder core magnetic ring

Iron powder core magnetic rings are composed of carbon-based ferromagnetic powder and resin carbon-based ferromagnetic powder, and have a very low magnetic permeability. There is an air gap between magnetic powder and insulating material, and the general magnetic permeability is between 20 and 100. It is precisely because the magnetic permeability of iron powder core magnetic rings is very low that they are not prone to saturation under differential mode large current conditions. Therefore, iron powder core magnetic rings are often used to make differential mode inductors. Iron powder core rings are distinguished by two colors in terms of material, commonly including -2 (wire/transparent), -8 (yellow/red), -18 (green/red), -26 (yellow/white), and -52 (green and blue). The iron powder core filter has a very low frequency band and is mainly used to suppress differential mode interference conducted by power lines.

Iron-silicon-aluminum magnetic rings

Iron-silicon-aluminum magnetic rings are one of the most frequently used magnetic rings. Composed of aluminum, silicon and iron, they have a relatively high BMAX(the average maximum magnetic flux density across the cross-sectional area of the magnetic core). Their core loss is much lower than that of iron powder cores. With high magnetic flux and low hysteresis (low noise), they are low-cost energy storage materials without thermal aging and can be used to replace iron powder cores. It performs very stably at high temperatures. The most prominent feature of iron-silicon-aluminum is its lower loss compared to iron powder cores, excellent DC deflection characteristics, and its price lies between that of iron powder cores and iron-nickel cores. Iron-silicon-aluminum magnetic powder cores feature excellent magnetic properties, low power consumption, high magnetic flux density, and high reliability such as high-temperature resistance, moisture resistance, and vibration resistance. A wide magnetic permeability range is available for selection, making it the best choice for common mode inductors, PFC inductors, and resonant inductors in switching power supplies. It offers a high cost-performance ratio, and iron-silicon-aluminum is generally all black.

Amorphous magnetic ring

Amorphous magnetic rings are magnetic ring-shaped structure devices made of amorphous materials, usually made of metal alloys with high magnetic permeability. This is a special type of material with unique magnetic and conductive properties. Compared with traditional crystalline magnetic materials, it has a higher saturation magnetic induction intensity, lower hysteresis loss and a wider frequency response range

According to the different materials used in amorphous magnetic rings, they can be classified into iron-based amorphous, cobalt-based amorphous, etc. According to the shape of the materials used, they can be divided into metal type magnetic rings and powder type magnetic rings. Amorphous alloys, also known as metallic glasses, refer to a kind of amorphous material with a special structure and complex composition composed of multiple metals. When manufacturing amorphous magnetic rings, powders of different metals are melted under vacuum, mixed uniformly, and then rapidly cooled to form amorphous alloy materials. Finally, the amorphous alloy materials are made into magnetic rings or magnetic strips with specific shapes, lengths, widths, materials and other dimensions. Amorphous magnetic rings are mostly black or white, and their casings are usually made of plastic. Compared with ferrite materials, they have a higher magnetic permeability. Amorphous magnetic rings are typically used to wind common-mode inductors to suppress low-frequency conducted common-mode interference.