Design principle of high frequency transformer
In the design of high frequency transformer, the leakage inductance and distributed capacitance of transformer must be minimized, because the high frequency transformer transmits the high frequency pulse square wave signal in the switching power supply.In the transient process of transmission, leakage inductance and distributed capacitance will cause surge current and peak voltage, as well as top oscillation, resulting in increased loss.Usually the leakage inductance of the transformer is controlled at 1% ~ 3% of the primary inductance.
Leakage inductance of primary coil - leakage inductance of transformer is caused by incomplete coupling of flux between primary coil and secondary coil, layer to layer, and turn to turn.
Distributed capacitance -- the capacitance formed between the transformer winding turns, between the upper and lower layers of the same winding, between different windings and between the winding and the shielding layer is called distributed capacitance.
Primary winding -- the primary winding should be placed in the innermost layer, which can make the transformer's primary winding use the shortest length of wire for each turn, thus making the whole winding use the least wire, which effectively reduces the primary winding's own distributed capacitance.
Secondary winding -- the primary winding is finished, and the secondary winding is made by winding (3 ~ 5) layer of insulation cushion.In this way, the capacitance of distributed capacitance between primary winding and secondary winding can be reduced, and the insulation strength between primary and secondary can also be increased, which meets the requirements of insulation withstand voltage.
Bias winding - the bias winding is wound between the primary and secondary, or wound in the outermost layer, and the switch power supply adjustment is based on the secondary voltage or primary voltage.
The key word for this information is： working transformer Definition inductor Design characteristics inductance inductive selection frequency differential difference principle common resonant
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