1.?About Soft Magnetic?FerritesFerrite is a new type of non-metallic magnetic material, which is a compound of iron oxide and other metal oxides.?In fact, all the magnetic phenomena in metallic magnetic materials can be observed in ferrites.?But there are two basic differences. One is that the saturation magnetization of ferrite is far lower than that of metal magnetic materials; the other is that the resistance of ferrite is several orders of magnitude higher than that of metal. Therefore, metal magnetic materials are generally used for power frequency and low frequency high power cores, and ferrite is used for high frequency cores.
1. About Soft Magnetic Ferrites
Ferrite is a new type of non-metallic magnetic material, which is a compound of iron oxide and other metal oxides. In fact, all the magnetic phenomena in metallic magnetic materials can be observed in ferrites. But there are two basic differences. One is that the saturation magnetization of ferrite is far lower than that of metal magnetic materials; the other is that the resistance of ferrite is several orders of magnitude higher than that of metal. Therefore, metal magnetic materials are generally used for power frequency and low frequency high power cores, and ferrite is used for high frequency cores.
Soft magnetic ferrite is a ferromagnetic oxide mainly composed of Fe2O3, which is produced by powder metallurgy. There are Mn-Zn, CuZn, Ni-Zn and so on. Among them, the output and consumption of Mn-Zn ferrite is the largest. The resistivity of MnZn ferrite is low, ranging from 1 to 10 Ohm-m. It is generally used at frequencies below ferrite core 100 kHZ. The resistivity of CuZn and Ni-Zn ferrites is 102-104 Ohm-m, and the loss in the radio frequency band of 100 kHz-10 MHz is small. They are mostly used in antenna coils and radio intermediate frequency transformers.There are many kinds of core shapes, such as E, I, U, EC, ETD, square (RM, EP, PQ), tank (PC, RS, DS) and circular etc. It is very convenient in application. Because soft magnetic ferrite can obtain high permeability without using scarce materials such as nickel. And powder metallurgy method is suitable for mass production, so it has a low cost, and because of its high hardness and insensitivity to stress, it is very convenient in application. Moreover, the permeability is steady with the changes of frequency and remains unchanged below 150 kHz. With the emergence of soft magnetic ferrites, the production of magnetic powder cores has been greatly reduced. Magnetic powder cores were replaced by soft magnetic ferrites in many places.
2. Production level of MnZn power materials:
The special study report of China Association of Magnetism Materials Industry and Information Network points out that: Under the existing conditions of raw materials and equipment in China, the performance of mass production products is around PC40, and it is quite difficult to produce qualified PC44 materials in batches in nitrogen kilns. From the performance level of domestic products, the low-grade products of soft magnetic ferrites in China occupy more than 60% of the domestic and foreign markets, and the high-grade products are gradually becoming more and more competitive. The power soft magnetic ferrites with high performance PC40 and above accounts for only 20% of the total domestic output in 2003, 23% in 2004, 28% in 2005, 32% in 2006 and 37% in 2007.
3. EE TYPE CORE
Type of EE core has a large space of wire-wrapping and it is easy for winding and wiring. It can be used in a wide range of application. The core has some advantages, such as high working efficiency and wide range of operating voltage. EE Core is assembled easily and fast, which is easy to automatic production. It is widely used in various fields, such as power supply of program-controlled switch, power supply of liquid crystal display, power supply of high-power UPS inverter, power supply of computer and energy-saving lamp, etc.
Take EE13/12/6 for an example:
A=13.3±0.3 Bmin=10.0 C=2.7±0.2 D=5.8±0.2 E=4.8±0.2 F=6.2±0.2
(2) EFFECTIVE PARAMETER
C1mm-1=1.88 Lemm=30.3 Aemm2=16.0 Vemm3=487.0
TP40=1000 TH5=1900 TH7=2500 TH10=4300
The following are the specifications provided by our factory.
4. Inductor core
Iron core inductor is a basic component, which has an impedance effect on the change of current in an inductor circuit, and is widely used in electronic equipment. The main requirements for inductors are as follows:
(1) The inductance of inductor should keep the minimum change rate with time when it works at a certain temperature for a long time.
(2) The temperature coefficient of inductance should be kept within the allowable limit under the given operating temperature range.
(3) Low electric and magnetic losses of inductors.
(4) The non-linear ambiguity becomes smaller.
(5) Low price, small size.
The most commonly used are power inductor filter choke coil and AC choke coil (including inductor coil). Inductor coils are mostly used in high frequency circuits, such as inductor coils for filters, inductor coils for oscillating circuits, notch coils, high frequency inductor choke coils, matching coils, noise filter coils, etc. Most of the cores work in AC state, and ferrite cores are used most frequently.
Transformer is a kind of passive device widely used in electronic circuits. It can transform AC (or signal) voltage, current and impedance by mutual inductance between coils. It can transmit signals. Transformers such as blocking DC are generally composed of coils, ferromagnetic cores and bobbins. They are usually expressed in English letters "T" or "B" in electronic circuits.
The function of transformer bushing is to bring the high and low voltage lead bow inside the transformer to the outside of the tank. As the ground insulation of the lead and the role of fixed lead, transformer bushing is one of the current-carrying components of transformer. During the operation of transformer, it passes through the load current for a long time and through the short-circuit current when the external short-circuit of transformer occurs. Therefore, there are the following requirements for transformer bushing:
(1) It must have specified electrical strength and sufficient mechanical strength.
(2) It must have good thermal stability and be able to withstand instantaneous overheating in short circuit.
(3) Small shape, small quality, good sealing performance, strong versatility and easy maintenance.