Transformer without Y capacitor and preparation method thereof

Abstract

The invention discloses a transformer without Y capacitor, comprising a magnetic core, a primary main winding, a secondary winding and an auxiliary winding, wherein the primary main winding, the secondary winding and the auxiliary winding are successively winded on the magnetic core. The transformer further comprises a primary shielded winding connected with the primary main winding and a secondary shielded winding connected with the secondary winding, wherein the primary shielded winding and the secondary shielded winding have the same number of loops and the same phase. The invention solvestwo main problems of electromagnetic radiation and electric leakage in a switch power supply at the same time, realizes that the switch power supply can pass an electromagnetic radiation test withoutY capacitor, so the transformer is suitable for products fairly sensitive to leakage current, such as mobile phone chargers.

Description

technical field

[0001] The invention relates to a transformer structure, in particular to a Y-capacitor-less transformer capable of reducing electromagnetic radiation. Background technique

[0002] The electromagnetic radiation interference source signal is divided into two forms: differential mode and common mode. Selecting an appropriate differential mode inductor to form a JI filter, or adding an X capacitor can solve the problem of differential mode. The problem of common mode is quite difficult, and the cost of simply starting from suppression is too high, and the effect is not obvious. It is necessary to solve the problem from the source. Most of the common-mode interference noise of the switching power supply comes from the transformer, and the primary high-frequency noise inside the transformer passes through the parasitic capacitance (such as Figure 5 C3) in C3) is coupled to the secondary, and then coupled to the conduction receiving instrument through the parasit...

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