1. High frequency class: Ferrite core
Ferrite core is used in high-frequency transformers. It is a ceramic magnet with a spinel crystal structure. The spinel is iron oxide and other divalent metal compounds. Such as kFe2O4 (k represents other metals), the current commonly used metals are manganese (Mn), zinc (Zn), nickel (Ni), magnesium (Ng), copper (Cu).
Its common combinations are Mn Zn series, Ni Zn series and Mg Zn series. This material has high magnetic permeability and resistance properties, and its frequency of use ranges from 1 kHz to over 200 kHz.
2. Low frequency class: LAMINATION
Silicon steel sheet is used for low-frequency transformers. There are many different kinds of silicon steel sheets. According to their different manufacturing processes, they can be divided into A: calcined (black sheet), N: no calcined (white sheet). According to its shape can be divided into: EI type, UI type, C type, mouth type.
Mouth-type silicon steel sheet is often used in transformers with large power. It has good insulation performance, easy to dissipate heat, and magnetic short circuit. It is mainly used in power transformers larger than 500~1000W and high power transformers.
A set of silicon steel plates consisting of two C-type silicon steel plates is called a CD-type silicon steel plate. The power transformer made of a CD-type silicon steel plate has the same cross-sectional area and the higher the window, the higher the transformer power. The coils can be installed on both sides of the core respectively, so the number of turns of the transformer can be distributed on two wire bundles, so that the average length of each wire bundle is shorter and the copper consumption of the coil is reduced. In addition, if the two coils requiring symmetry are respectively wound on two wire bundles, a completely symmetrical effect can be achieved.
A set of silicon steel sheets consisting of four C-type silicon steel sheets is called an ED-type silicon steel sheet. The shape of the transformer made of ED silicon steel sheet is flat and wide. Under the same power conditions, the ED type transformer is shorter than the CD type transformer, and the width is larger. In addition, since the coil is installed in the middle of the silicon steel sheet, there is an external magnetic circuit, so the leakage Magnetic small, small overall interference. However, all of its coils are wound on a wire package. The wire package is thicker, so the average length of the coil is longer and the copper consumption is larger.
The transformer produced by the excellent performance of the C-type iron core is small in size, light in weight, and high in efficiency. From the perspective of assembly, the C-type silicon steel sheet has few parts and high versatility, so the production efficiency is high, but the processing procedure of the C-type silicon steel sheet is comparatively low. Too many, more complex, need to use special equipment to manufacture, so the current cost is still high.
We mainly use EI silicon steel sheet. E-type silicon steel sheet is also called shell type or Japanese type silicon steel sheet. Its main advantage is that the primary and secondary coils share a common wire frame and have a higher window occupancy factor (duty ratio Km: copper wire net cross-sectional area and window Area ratio); The silicon steel sheet forms a protective shell for the windings, making the windings less susceptible to mechanical damage; at the same time, the silicon steel sheet has a large heat dissipation area and the magnetic field of the transformer is less divergence. However, its primary and secondary leakage inductance is large, and the external magnetic field interference is also large. In addition, due to the longer average winding length, under the conditions of the same number of turns and the core cross-sectional area, the copper used in the transformer of the EI type core is comparatively many.
The thickness of silicon steel sheet is commonly used 0.35mm, 0.5mm two.
There are two methods for assembling the silicon steel sheet: overlap method and overlap method. The overlap method is to alternately distribute the opening of the silicon steel sheet one to one on both sides. This stacking method is more troublesome, but the gap between the silicon steel sheet is small and the magnetic resistance is small, which is favorable for increasing the magnetic flux. Therefore, the power transformer adopts this method. . The overlap method is often used in applications where DC current is common. To avoid saturation due to DC current, gaps need to be left between the silicon steel sheets. Therefore, the stacking method separates the E-sheet and the I-sheet, and the gap between the two can be used as paper. Tablets to adjust.
Our factory commonly used silicon steel materials are Z-11, H-18, H-50, H-14, etc.
The Z-11 silicon steel sheet has the best performance. The usual representation method is shown in Figure 1:
3.COIL categories: divided into three types (Figure 2)
A.TOROID ring core: O-type laminated sheet, or made of silicon steel sheet. This core is very difficult for winding.
BBROD CORE rod core.
C.DRUM CORE: drum core.
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