Analysis on near-field effect caused by stray magnetic field of integrated LLC transformer

In LLC resonant converter, the integrated transformer with high leakage inductance is preferred to get high power density by eliminating the series resonant inductor. However, high leakage inductance results from stray magnetic field between primary winding and secondary winding, which brings near-field effect and severely impacts on near-by components. In this paper, the mechanism of near-field effect is discussed and the model of the integrated transformer applied in LLC converter is built. Furthermore, this paper takes the metal case of power supply for example to analyze the near-field phenomenon. Based on an 185W power supply, both simulation and experiment results are carried out. The near-field phenomena get well explanation.