A Multi-mode Combined Control Method for Wide Input Voltage Application Based on Series-half-bridge LLC Resonant Converter

The series-half-bridge (SHB) LLC resonant converter, is suitable for the wide range input voltage applications. This paper presents that it can operate in the two-level mode, double-frequency mode, and three-level mode. Subsequently, a multi-mode combined control method is proposed to select the optimal operating mode combination under different gain ranges of converters. The proposed method can significantly reduce the frequency variation range of the converter compared to the traditional LLC resonant converter, thereby improving the conversion efficiency. The effectiveness of this method has been verified through simulations in PLECS.