Small Signal Modeling of LLC Resonant Converters Based on Extended Describing Function

Due to the advantages of low switching loss and high efficiency, LLC resonant converters have been widely used. Based on the extended describing function concept, the small-signal model of an LLC resonant converter is derived in this paper. The equivalent circuit of small-signal model is illustrated so that the corresponding frequency response can be easily obtained by using IsSpice simulation. The well agreement with experimental measurements has verified the accuracy of the derived small-signal model.