1. High-frequency category: iron powder core Ferritecore
Ferritecore used in high-frequency transformers it is a ceramic magnet with a crystalline structure of spinel, such spinel for iron oxide and other bivalent metal compounds. Such as kFe2O4 (k on behalf of other metals), the current commonly used metals are manganese (Mn), zinc (Zn), nickel (Ni), magnesium (Ng), copper (Cu).
The common combination of manganese-zinc (MnZn) series, nickel-zinc (NiZn) series and magnesium-zinc (MgZn) series. This material has a high permeability and impedance properties, the use of frequency range from 1kHz to more than 200kHz.
2. Low-frequency class: silicon steel sheet (LAMINATION)
Silicon steel sheet used for low-frequency transformers, there are many types of silicon steel sheet according to the different production processes can be divided into A: forging (black sheet), N: no forging (white sheet) two kinds. According to its shape can be divided into: EI type, UI type, C type, mouth type.
The mouth type silicon steel sheet is often used in the larger power transformer, it is good insulation, easy to dissipate heat, while the magnetic circuit is short, mainly used for power greater than 500 ~ 1000W and high-power transformers. By two C-type silicon steel sheet composed of a set of silicon steel sheet called CD-type silicon steel sheet, with CD-type silicon steel sheet made of power transformers in the same cross-sectional area under the condition of the higher the window.
The higher the transformer power. On both sides of the core can be installed separately coil, so the number of turns of the transformer coil can be distributed in two packages, so that the average turn length of each package is shorter, the coil copper consumption is reduced. In addition, if the two coils that require symmetry are wound on two bales of wire, complete symmetry can be achieved. By four C-type silicon steel sheet composed of a set of silicon steel sheet called ED-type silicon steel sheet. ED-type silicon steel sheet made of transformer shape is flat and wide, in the same conditions of power ED-type transformer than the CD-type transformer shorter, wider, in addition, because the coil is mounted in the middle of the silicon steel sheet, there is an external magnetic circuit, and therefore leakage of magnetism is small, on the overall interference is small. But it all coils are wound on a wire package, the wire package is thicker, so the average turn length is longer, copper consumption is larger.
C-type iron core with excellent performance of the transformer produced by the small size, light weight, high efficiency, assembly point of view, C-type silicon steel sheet parts are few, versatile, and therefore high production efficiency, but C-type silicon steel sheet processing process is more, more complex, need to be manufactured with special equipment, and therefore the cost of the current is still relatively high.
E-type silicon steel sheet, also known as shell-type or day-type silicon steel sheet, its main advantage is that the primary and secondary coil **** the same wire frame, a higher window duty factor (duty factor Km: the net cross-sectional area of the copper wire and the window area ratio); silicon steel sheet on the formation of the windings to protect the shell, so that windings are not easy to be injured by mechanical damage; at the same time, the silicon steel sheet cooling area is larger, the magnetic field of the transformer dispersal is less. But it is the initial level of leakage inductance is larger, external magnetic interference is also larger, in addition, due to the winding average circumference is longer, in the same number of turns and core cross-sectional area conditions, EI-type core transformer used in the more copper wire.
Silicon steel sheet thickness commonly used 0.35mm, 0.5mm two kinds.
Silicon steel sheet assembly method has two kinds of cross-stacking and stacking method. Cross-stacking method is the opening of the silicon steel sheet one to one alternately distributed on both sides, this stacking method is more troublesome, but the silicon steel sheet gap is small, magnetoresistance is small, is conducive to increasing the magnetic flux, so the power transformer are used in this way. Pair of stacked method is commonly used in the occasions of DC current, in order to avoid saturation caused by DC current, silicon steel sheet needs to leave a gap between, so the pair of stacked method will be the E piece and the I piece of one side, the gap between the two can be adjusted with a piece of paper.
3. COIL category: three types.
A. TOROID ring core: O-type stacked and become, or by the silicon steel coil and become. This type of core is very difficult for winding.
B.RODCORE bar core.
C.DRUMCORE: Drum shaped core.