Transformer core content sharing
The iron core is the main part of the magnetic circuit in the transformer. It is usually composed of hot-rolled or cold-rolled silicon steel sheets with high silicon content and coated with insulating paint. The iron core and the coil wound on it form a complete electromagnetic induction system. The amount of power transmitted by a power transformer depends on the material and cross-sectional area of the iron core. Classification introduction 1. High frequency class: Ferritecore Ferritecore is used for high frequency transformers. It is a ceramic magnet with a spinel crystalline structure. This spinel is iron oxide and other divalent metal compounds. Such as kFe2O4 (k represents other metals), currently commonly used metals are manganese (Mn), zinc (Zn), nickel (Ni), magnesium (Ng), copper (Cu). Its commonly used combinations such as manganese zinc (MnZn) series, Nickel-zinc (NiZn) series and magnesium-zinc (MgZn) series. This material has high magnetic permeability and impedance properties, and its use frequency range is from 1kHz to more than 200kHz. 2. Low frequency: silicon steel sheet (LAMINATION) For low-frequency transformers, there are many types. According to their different production processes, they can be divided into two types: A: calcined (black sheet) and N: non-calcined (white sheet). According to their different shapes, they can be divided into: EI type, UI type , C type, mouth type. Mouth-shaped silicon steel sheet is often used in high-power transformers. It has good insulation performance, easy to dissipate heat, and has a short magnetic circuit. It is mainly used for power transformers greater than 500~1000W and high-power transformers. A set of silicon steel sheets composed of two C-type silicon steel sheets is called CD-type silicon steel sheets. The power transformer made of CD-type silicon steel sheets has the same cross-sectional area, the higher the window. The greater the power of the transformer. The coils can be installed on both sides of the iron core, so the number of turns of the transformer coil can be distributed on the two coils, so that the average turn length of each coil is shorter, and the copper loss of the coil is reduced. In addition, if the two coils that require symmetry are wound on two coils respectively, a completely symmetrical effect can be achieved. A set of silicon steel sheets composed of four C-type silicon steel sheets is called ED-type silicon steel sheets. The shape of the transformer made of ED-type silicon steel sheets is flat and wide. Under the same power conditions, the ED-type transformer is shorter than the CD-type transformer. In addition, because the coil is installed in the middle of the silicon steel sheet, there is an external magnetic circuit, so the magnetic flux leakage is small, and the overall interference is small. However, all coils are wound on a coil, and the coil is thick, so the average turn length is longer. , the copper consumption is large. The transformers made of C-type iron cores with excellent performance are small in size, light in weight and high in efficiency. From the perspective of assembly, there are few C-type silicon steel sheet parts and strong versatility, so the production efficiency is high, but the C-type silicon steel sheet processing process is relatively It is more complicated and needs to be manufactured with special equipment, so the current cost is still relatively high. E-type silicon steel sheet, also known as shell-type or Japanese-type silicon steel sheet, its main advantage is that the primary and secondary coils share the same wire frame, and have a higher window space factor (space factor Km: copper wire net cross-sectional area and window Area ratio); the silicon steel sheet forms a protective casing for the winding, so that the winding is not easily damaged by mechanical damage; at the same time, the silicon steel sheet has a larger heat dissipation area, and the transformer magnetic field diverges less. However, its primary and secondary leakage inductance is larger, and the external magnetic field interference is also larger. , In addition, due to the longer average perimeter of the winding, under the same number of turns and core cross-sectional area, the EI core transformer uses more copper wires. The thickness of silicon steel sheet is commonly 0.35mm and 0.5mm. There are two ways of assembling silicon steel sheets: overlapping method and anti-stacking method. The overlapping method is to distribute the openings of the silicon steel sheet on both sides alternately one-to-one. This method of stacking is more troublesome, but the gap between the silicon steel sheets is small and the magnetic resistance is small. , which is beneficial to increase the magnetic flux, so this method is used for power transformers. The stacking method is often used in occasions where there is a DC current. In order to avoid saturation caused by the DC current, a gap needs to be left between the silicon steel sheets, so the stacking method will Put the E and I pieces aside, and the space between them can be adjusted with paper pieces. 3.COIL category: divided into three types. A.TOROID ring core: O-shaped lamination, or made of silicon steel sheet winding. This core is very difficult for winding. B.RODCORE rod core. C.DRUMCORE: drum core. 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