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high frequency transformer are mainly used for power transmission and distribution system from the power transmission, voltage conversion and insulation isolation role in the application of the use of conditions include two aspects: reliability and electromagnetic compatibility. Previously only pay attention to reliability, and now due to increased awareness of environmental protection, we must pay attention to electromagnetic compatibility.

Reliability refers to the specific conditions of use, high-frequency power transformer can work until the normal life so far. General use conditions for high frequency power transformer is the greatest impact on the ambient temperature. Some soft magnetic materials, Curie point is relatively low, sensitive to temperature. For example, manganese zinc soft ferrite, Curie point only 215 ¡æ, magnetic flux density, permeability and loss are changing with temperature, in addition to the normal temperature of 25 ¡æ, but also given 60 ¡æ, 80 ¡æ, 100 ¡æ When the various reference data. Therefore, the temperature of manganese-zinc soft ferrite core is limited to 100 ¡æ below, that is, the ambient temperature of 40 ¡æ, the temperature rise is only allowed to less than 60 ¡æ, equivalent to A-class insulation temperature.

Electromagnetic compatibility by high frequency transformer manufacturers refers to the high-frequency power transformer does not produce external electromagnetic interference, but also to withstand external electromagnetic interference. Electromagnetic interference includes audible audio noise and non-audible high frequency noise. One of the main causes of electromagnetic interference in high frequency power transformers is the magnetostriction of the core. Magnetostrictive large soft magnetic material, resulting in large electromagnetic interference. High-frequency power transformer electromagnetic interference caused by the main reason there is the magnetic force between the core and the winding between the repulsion. The frequency of these changes in frequency and high frequency power transformer operating frequency consistent.

Shielding is to prevent electromagnetic interference, increase the high-frequency power transformer electromagnetic compatibility of a good way. However, in order to prevent the transmission of electromagnetic interference from high-frequency power transformers, the corresponding measures should be taken in the design of the core structure and the design of the winding structure. The addition of the external shield is not necessarily the best solution because it can only prevent radiation interference , Can not prevent conduction transmission interference.

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high frequency transformer leakage inductance should be the primary coil generated by the magnetic field lines can not all through the secondary coil will miss a part, so the leakage of magnetic inductance known as leakage inductance.

The general leakage of the problem with the winding line of the law, the thickness of the interlayer insulation, winding width and many other factors. General measures to reduce leakage are:

1 Each set of windings must be tightened and distributed evenly by high frequency transformer manufacturers

2 leads to the place to be quite satisfactory, as far as possible at right angles, close to the skeleton wall

3 can not be full of a layer of the average to cover a layer full

4 insulation layer to minimize, to meet the pressure requirements and can be

5, such as more space, you can consider the extension of the skeleton, to minimize the thickness of the transformer can not blindly ask the leakage of small, reduce the leakage of the measures tend to make the distribution of capacitance increases, the distribution of high capacitance will also produce inrush current and peak voltage And the pulse at the top of the shock, resulting in increased wear and tear.

Any transformer there is leakage inductance, but the leakage inductance of the switching transformer on the switching power supply performance indicators is particularly important. Due to the existence of switching transformer leakage inductance, when the control switch off the moment will produce back electromotive force, easy to switch device over-voltage breakdown; leakage inductance can also be distributed with the circuit capacitance and transformer coil distributed capacitor oscillation circuit The circuit generates oscillations and radiates radiated energy, causing electromagnetic interference.

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