Design consideration of low-profile LLC resonant converter for reducing temperature of the transformer

Abstract

This paper presents the design consideration of a low-profile LLC resonant converter using two flat trans- formers. The trend toward high power density, high efficiency, and low profile in power supplies has exposed a number of limitations in the use of magnetic component structures. The LLC resonant converter can be operated at a high switching frequency with high efficiency because the switching loss is reduced by soft-switching. However, flat transformer loss causes problems at a high switching frequency. As a result, temperature of flat transformers becomes high. Therefore, it is necessary to reduce the transformer temperature by analyzing the loss. In this proposed con- verter, flat transformer is integrated into advanced power conversion application systems. Low-profile power module of profile of about 14mm is achieved. Temperature inside of transformer repressed to 66.5 ℃ and an overall efficiency of about 96.5% was obtained.