Design method of auxiliary winding of switching power supply high frequency transformer for suppressing common mode EMI

Abstract

The invention discloses a method for designing an auxiliary winding of a switching power supply high-frequency transformer to inhibit common-mode electromagnetic interference (EMI). According to the method, by a measure of reasonably designing an anti-phase auxiliary winding on the primary side of the transformer, the common-mode conducted EMI of a switching power supply is inhibited in high performance. The anti-phase auxiliary winding connected in parallel with a primary winding of the transformer is designed according to a zero equipotential line theory, an electric field generated by the anti-phase auxiliary winding eliminates common-mode noise voltage of primary and secondary windings, and common-mode conducted EMI noise caused by a coupling capacitor between the primary winding and the secondary winding of the transformer is effectively inhibited. According to the method, the common-mode conducted EMI noise is effectively inhibited, the loss of the switching power supply for the transformer is effectively reduced, the volume of the power supply can be greatly reduced and the energy conversion efficiency is improved.

Description

technical field [0001] The invention belongs to the technical field of switching power supply transformer design, and in particular relates to a design method for an auxiliary winding of a switching power supply high-frequency transformer for suppressing common-mode EMI. Background technique [0002] As the switching frequency of switching power supplies continues to increase, EMI suppression becomes a great challenge in designing high-efficiency switching power supplies. The use of high-frequency transformer technology to suppress common-mode EMI noise can save the passive and active EMI suppression circuits in the switching power supply circuit, reduce power loss, reduce the physical size of the power supply, and improve the efficiency of the switching power supply. [0003] Existing high-frequency transformer technologies for suppressing common-mode EMI noise include: reducing the parasitic coupling capacitance technology between the main winding of the transformer and th...

AI Technical Summary

Problems solved by technology

This method can greatly reduce common-mode EMI noise, completely replace traditional passive EMI low-pass filters, and solve engineering problems such as suppression of common-mode EMI switching power supply high-frequency transformer leakage inductance increase, bypass capacitor design is difficult, and effective shielding is difficult to implement.

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