What Is a Magnetic Core?

Magnetic core: A magnetic core is a sintered magnetic metal oxide composed of various iron oxide mixtures. For example, manganese-zinc ferrite and nickel-zinc ferrite are typical magnetic core materials. Manganese-zinc ferrite has the characteristics of high magnetic permeability and high magnetic flux density, and has the characteristics of low loss. Nickel-zinc ferrite has characteristics such as extremely high resistivity and low magnetic permeability of less than a few hundred. Ferrite cores are used in coils and transformers of various electronic devices.

Magnetic core

Magnetic core: Magnetic core refers to a kind of sintered magnet composed of various iron oxide mixtures

Magnetic core (magnetic ring)

[ Pronunciation ] ci xin

American physicist Wang An put forward the idea of using magnetic materials to make memories in 1950. Forrest turned this idea into reality. In order to achieve magnetic core storage, Forrest needs a substance that should have a very clear magnetization threshold. He found an old German ceramic expert at a company that produces ferrite converters for televisions in New Jersey, using molten iron ore and oxides to obtain specific magnetic properties.

Having a clear threshold for magnetization is the key to the design. The grid and core of this kind of wire are woven on the wire network, known as core storage, and its related patents are very important for the development of computers. This solution is reliable and stable. Magnetization is relatively permanent, so the stored data is retained after the system power is turned off. Since magnetic fields can be read at the speed of electrons, this makes interactive computing possible. Furthermore, because it is a wire grid, any part of the storage array can be accessed, that is, different data can be stored at different locations in the wire network, and a bunch of bits at the location can be accessed immediately. This is called Random Access Memory (RAM) and it is an innovative concept for interactive computing. Forrest transferred these patents to the Massachusetts Institute of Technology, and the college receives $ 15 million to $ 20 million a year from these patents.

The first to obtain these patent licenses was IBM, which eventually won a commercial contract to install the Tornado at a North American defense military base. What's more, this system has also been adopted by all large and medium computers since the 1950s. Magnetic core storage has been the standard method of computer main memory from the 1950s and 1960s to the early 1970s.

The magnetic ring we usually see at one or both ends of the power or signal lines of electronic equipment is the common mode choke. The common mode choke coil can form a large impedance to the common mode interference current, but has no effect on the differential mode signal (the working signal is a differential mode signal), so it is simple to use without considering the problem of signal distortion. And the common mode choke does not need to be grounded, and can be directly added to the cable. The number of turns of the magnetic ring will select the entire beam

Laminated sheet is usually punched and cut from silicon steel or nickel steel sheet into E, I, F, O and other shapes, and laminated into an iron core.

Toroidal iron core is formed by stacking O-shaped sheets, and it can also be wound by narrow and long silicon steel and alloy steel strips.

C-shaped iron core. This type of iron core can avoid the disadvantages of difficult winding of the ring-shaped iron core. It is formed by butting two C-shaped iron cores.

A can-shaped iron core, which is a structure form in which a magnetic core is outside and a copper coil is inside, which avoids the inconvenience of a toroidal coil, and can reduce EMI. The disadvantage is that the internal coil has poor heat dissipation and higher temperature rise. ^[1]

TDK Core Product Description

PC40 EF20-Z core 240501

PC40 EER42 / 42 / 15-Z core 16230

PC40 EE16-Z core 299930

PC40 EER42 / 42 / 20-Z core 13335

PC40 EE19 / 27 / 5-Z core 93300

PC44 PQ26 / 20Z-12 core 26880

PC40 EF25-Z core 81497

PC40 EI33 / 29 / 13-Z core 20848

PC44 PQ32 / 30Z-12 core 10533

PC40 EE55 / 55 / 21-Z core 3708

Q1C DR1.6X1.7D29 core 908000

PC40 EER28L-Z core 23071

PC44 PQ50 / 50Z-12 core 510.5

PC40 EE19 / 16-Z core 100430

PC44 PQ40 / 40Z-12 core 1182

PC40 EI28-Z core 18656

RM Core Introduction

In addition to pot-shaped cores, ferrite cores come in many other shapes. One popular type is the RM (Rectangular Module, square) core.

Because they are square or rectangular, they have higher PCB area utilization efficiency than circular cores. Multiple RM cores can be placed closer together physically. Although RM cores provide fewer closed magnetic circuits than pot-shaped cores, there are more between the cores.

The deflection core is used to control the electron beam deflection. These electromagnets are usually mounted on the outside, near the neck and where the bucket is connected, and consist of a series of windings moulded to match the shape of a glass picture tube. The component attached to the bucket as a deflector is called a deflection core.

Core Wars circa 1959.

Silicon steel sheet iron core

Silicon steel sheet is an alloy. An iron-silicon alloy formed by adding a small amount of silicon (generally below 4.5%) to pure iron is called silicon steel. This type of iron core has the highest saturation magnetic induction intensity value of 20,000 Gs; because of their good magnetic and electrical properties, easy to mass-produce, cheap, low mechanical stress and other advantages, they have been widely used in the power electronics industry. Such as power transformers, distribution transformers, current transformers and other iron cores. It is the material with the largest output and usage among soft magnetic materials. Also for power transformers

Reduce the loss of the inductor core

Everyone knows that inductive magnetic core is a product that will be used in many electronic products, such as mobile phones, MP3, MP4, computers, converters, transformers and LED TV displays. And everyone should also know that electronic products generate certain losses in the process of use, and inductive magnetic core is no exception. However, if the loss of the inductive magnetic core is too large, it will lead to a reduction in the service life of the inductive magnetic core, and if it is serious, it will also affect the normal operation of the product using the inductive magnetic core. So how can we reduce the loss of the inductor core?

Causes of loss in the inductor core:

The loss of the chip inductor core mainly comes from the core loss and the coil loss, and the amount of loss in these two aspects needs to be judged according to its different circuit modes. Among them, the core loss is mainly caused by the alternating magnetic field in the core material. The loss it generates is a function of the operating frequency and the total magnetic flux swing (B), which will greatly reduce the effective conduction loss. Coil loss is the energy loss caused by the change in magnetic energy, which will reduce the strength of the magnetic field when the power inductor current decreases.

Method for reducing loss of inductive core:

1. The allowable copper wire loss that the core loss generated in an inductive core will decrease with the increase in the core loss of the inductive core will also cause a surge in the flux of the same inductive core material. Therefore, when the switching frequency rises above 500 kHz, the inductor core loss and winding AC loss can greatly reduce the allowable DC current in the inductor.

2. The loss of the inductor core in the coil is mainly represented by the copper wire loss. Therefore, if you want to reduce the copper wire loss, it must be reduced when the inductor core loss rises until all losses are equal. The best case is that the losses remain stable at high frequencies and allow maximum output current from the magnetic structure. ^[2]