Product Categories

Contact Us

Add: No.38 South Taoyuan Road, Yaozhuang Town,Jiashan County, Jiaxing City, Zhejiang Province, China
Contact person: Elva Zhuang&Sunny Ni
Tel:+86-573-84775555
Fax:+86-573-84776699
Phone:+86-13732570078
E-mail:sales9@great-relay.com
       sunny.ni@great-relay.com

Exhibition

Home > Exhibition > Content
Selection and design of magnetic cores in several common magnetic devices
Oct 20, 2017

Selection and design of magnetic cores in several common magnetic devices

The use of more magnetic devices in the switching power supply, the soft magnetic devices are commonly used as a main transformer core of switching power supply device (high frequency power transformer), common mode choke, high-frequency amplifier, filter chokes, spikes suppressor etc.. The performance requirements of different devices are different, such as the performance requirements of various devices for magnetic materials as shown in the table.

 high frequency power transformer

The size of the transformer core depends on the output power and temperature rise. The design formula of transformer is as follows:

P=KfNBSI * 10-6T=hcPchWPW

Among them, P for electric power; K coefficient and waveform related; F frequency; N is the number of turns; S core area; B for magnetic induction; I current; T temperature; Pc PW copper loss; iron loss; HC and hW on the grounds of the experimentally determined coefficients.

It can be seen from the above formula that the high working magnetic sense B can obtain large output power or reduce the volume weight. However, the increase of B value is limited by the Bs value of the material. The frequency f can be improved several orders of magnitude, so that the volume and weight can be reduced significantly. The low core loss can reduce the temperature rise, and the temperature rise, in turn, affects the selection of frequency and magnetic sense. In general, the main switching power supply requirements of the material is as low as: high-frequency loss, high saturation, high permeability, high enough for the Curie temperature and good temperature stability, some use of higher squareness, is not sensitive to stress, good stability, low price. Because the core of the single ended transformer works in the first quadrant of the hysteresis loop, the magnetic requirements of the material are different from those of the main transformer. It is actually a single ended pulse transformer, so it requires large B = Bm - Br, that is, the difference between magnetic induction Bm and remanence Br is large, and high pulse permeability is also required. Especially for the single ended flyback switch main transformer, or energy storage transformer, the energy storage requirements should be considered. Source: www.tede.cn

The amount of coil energy storage depends on two factors: one is the work magnetic sense Bm value or inductance L, the other is the working magnetic field Hm or working current I, energy storage W = 1/2LI2. This requires that the material has high enough Bs value and suitable permeability, often wide and constant magnetic conductivity material. For transformer in the + Bm between, the hysteresis area, especially in the high frequency loop area is smaller, at the same time to reduce no-load loss, reduce the excitation current, due to high permeability, the most suitable for the closed ring core, see the hysteresis loops shown, the core device for double end or full bridge of working state.

Usually, the metal crystalline materials to reduce the loss of high frequency is not easy, but for the amorphous alloys, they do not exist due to magnetocrystalline anisotropy, metallic inclusions and grain boundaries, in addition it does not exist the atom long range order, the amorphous alloy resistivity than the average height of 2 to 3 times, and the fast cooling method to form a 15-30 micron thickness of amorphous ribbons, especially suitable for high frequency power output transformer. Has been widely used in arc welding inverter, single pulse transformer, high frequency induction heating power supply, uninterruptible power supply, power transformer, communication power supply, switching power supply transformer and high energy accelerator core at the frequency of 20 50kHz, power 50kW, is the best material of transformer core.

The new inverter arc welding power supply is developed in recent years at one end of the pulse transformer has the characteristics of high frequency and high power, so the transformer core material with low loss at high frequency, high saturation and low Bs Br to get a greater sense of magnetic B, make the machine size and weight reducing. Commonly used core materials for high frequency welding power ferrite, although due to its high resistivity and high frequency low loss, but its poor temperature stability, low working magnetic transformer, large volume and weight, has been unable to meet the new requirements of arc welding machine. The nanocrystalline toroidal core, because of its high Bs value (Bs, 1.2T), a high B value (B, 0.7T), high pulse permeability and low loss, frequency up to 100kHz. can make the core size and weight is greatly reduced. In recent years the application of nanocrystalline core welding inverter has reached tens of thousands of users reflect again with the welder made of amorphous nanocrystalline with high frequency inductance of the transformer core, not only has the advantages of small size, light weight, easy to carry, and the stable arc, little splash, good dynamic performance, high efficiency and high reliability. The ring shaped nanocrystalline iron core can also be used in middle and high frequency heating power supply, pulse transformer, uninterruptible power supply, power transformer, switching power transformer and high energy accelerator, etc.. The magnetic core material can be selected according to the frequency of switching power supply.

Toroidal nanocrystalline cores have many advantages, but they also have the disadvantage of winding difficulties. In order to make the winding more convenient when the number of turns is large, the high frequency and high power C amorphous nanocrystalline core can be selected. The performance of amorphous nanocrystalline alloy C core made by low stress binder curing and new cutting process is better than that of silicon steel C core. At present, this kind of iron core has been used in inverter welding machine and cutting machine. The main transformer iron core and reactor core series of inverter welding machine are: 120A, 160A, 200A, 250A, 315A, 400A, 500A, 630A series.


Add: No.38 South Taoyuan Road, Yaozhuang Town,Jiashan County, Jiaxing City, Zhejiang Province, China
Contact person: Elva Zhuang&Sunny Ni
Tel:+86-573-84775555
Fax:+86-573-84776699
Phone:+86-13732570078
E-mail:sales9@great-relay.com
       sunny.ni@great-relay.com