A winding method of high frequency high voltage transformer

Abstract

The high frequency high voltage (HFHV) transformer is one of the biggest contributors for conducted electromagnetic interference (EMI) emission of switching power supply. The transformer technologies for reducing conducted EMI emission focus on the shielding and changing the winding structures. However, for suppressing conducted EMI, the suppression capability of shielding is limited; current methods of changing the winding structures don't fully reduce all the distributed capacitance, especially in the HFHV switching power supply. This paper proposes a novel winding method to suppress the conducted EMI. The proposed method not only considers the distributed capacitance between the primary winding and secondary winding, the interlayer distributed capacitance of the primary or secondary winding, but also considers the interturn distributed capacitance of the winding. Experimental testbed based on 1kV DC switching power supply is built. Simulation and experimental results show the proposed winding method is very effective in reducing conducted EMI emission.