Transformer and power supply device

Abstract

The embodiment of the invention discloses a transformer and a power supply device. The transformer comprises a primary winding, a secondary winding, a shielding winding and an adjustable impedor; thefirst end or the second end of the primary winding is connected with the first end of the adjustable impedor, and the second end of the adjustable impedor is connected with the first end of the shielding winding; the adjustable impedor is a replaceable or adjustable impedance component; under the situation that the transformer is in access into a power supply circuit, when a switching tube of thepower supply circuit is switched between disconnecting and closing states, the direction of current produced by the shielding winding is opposite to the direction of the common mode current of the primary winding and the secondary winding, the adjustable impedor is used for adjusting the size of the current produced by the shielding winding, and the current produced by the shielding winding is equal to the sum of the common mode current produced by the primary winding and the secondary winding; wherein the number of turns of the shielding winding is a fixed value and larger than the thresholdvalue of the number of turns. According to the transformer and the power supply device, design and commissioning of the transformer can be simplified, the design validation cycle of the transformer isshortened, and the production cost is reduced.

Description

technical field [0001] The present application relates to the field of electric power, in particular to a transformer and a power supply device. Background technique [0002] The current power adapter must be tested for electromagnetic interference, and the electromagnetic noise generated must be lower than the limit set by international regulations on electromagnetic interference. Power adapter electromagnetic interference mainly includes differential mode noise and common mode noise. The high-speed switching of the power device of the power adapter will cause a voltage jump in the primary and secondary windings of the transformer, which will generate a displacement current through the parasitic capacitance of the transformer, forming common-mode noise of the power adapter. [0003] Generally, in order to suppress the common mode noise, it is mainly achieved by the following methods: adding a copper foil shielding layer to the transformer to shield the common mode current ...

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Problems solved by technology

[0004] However, there are the following problems in adopting the above-mentioned implementation method: 1. Copper foil shielding can only reduce the common-mode current generated by the primary winding or the common-mode current generated by the secondary winding, but does not fundamentally suppress the common-mode current of the primary and secondary windings; 2. It is difficult to realize automatic processing by using copper foil shielding method, and the production and winding of the shielding layer need to be completed manually, and the production cost is high

[0006] 1. It is difficult

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