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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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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.
More transformer in www.xp-elec.com
Any transformer there is leakage inductance, but the leakage inductance of the SMPS transformers
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 the device over-voltage breakdown;
leakage inductance and the circuit can be distributed in the capacitor
and the transformer coil distributed capacitor oscillation circuit The
circuit generates oscillations and radiates radiated energy, causing
electromagnetic interference. Therefore, the analysis of leakage
inductance generated by the principle and reduce the leakage inductance
is also one of the important components of the design of switching
transformers.
SMPS transformers manufacturer said, there is a leakage inductance between the switch transformer coils because of the leakage flux between the coils. Therefore, the value of the leakage inductance can be calculated by calculating the leakage flux between the coils. To calculate the leakage flux between the transformer coil, the first is to know the magnetic field distribution between the two coils. We know that the magnetic field distribution in the spiral coil is similar to the distribution of the electric field in the two plates, that is, the magnetic field intensity distribution in the spiral coil is substantially uniform and the magnetic field energy is concentrated in the helical coil. In addition, when calculating the distribution of the magnetic field intensity inside or outside the spiral coil, the more complex case can be used Maxwell's theorem or Bi-sand theorem, and the simpler case can be given by the Ampere loop law or the Kirchhoff law of the magnetic circuit.
The magnetic flux? 1 generated by the transformer primary coil N1 passes through the transformer secondary coil N2, and there should be no leakage flux therebetween; however, the direction of the magnetic flux? 1 generated in the area S1 in the area S1 and the magnetic energy generated in the area Sd2 The direction of the ¦Õ1, just opposite to each other; therefore, the transformer primary coil N1 in the area Sd2 generated in the magnetic flux ¦Õ1, still known as the transformer primary coil N1 transformer secondary coil N2 leakage flux, the equivalent inductance is also known as Leakage.
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SMPS transformers manufacturer said, there is a leakage inductance between the switch transformer coils because of the leakage flux between the coils. Therefore, the value of the leakage inductance can be calculated by calculating the leakage flux between the coils. To calculate the leakage flux between the transformer coil, the first is to know the magnetic field distribution between the two coils. We know that the magnetic field distribution in the spiral coil is similar to the distribution of the electric field in the two plates, that is, the magnetic field intensity distribution in the spiral coil is substantially uniform and the magnetic field energy is concentrated in the helical coil. In addition, when calculating the distribution of the magnetic field intensity inside or outside the spiral coil, the more complex case can be used Maxwell's theorem or Bi-sand theorem, and the simpler case can be given by the Ampere loop law or the Kirchhoff law of the magnetic circuit.
The magnetic flux? 1 generated by the transformer primary coil N1 passes through the transformer secondary coil N2, and there should be no leakage flux therebetween; however, the direction of the magnetic flux? 1 generated in the area S1 in the area S1 and the magnetic energy generated in the area Sd2 The direction of the ¦Õ1, just opposite to each other; therefore, the transformer primary coil N1 in the area Sd2 generated in the magnetic flux ¦Õ1, still known as the transformer primary coil N1 transformer secondary coil N2 leakage flux, the equivalent inductance is also known as Leakage.
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