Design for High-Voltage-Step-Down LLC Resonant Converter Based on Low-Winding-Turn-Ratio Planar Transformer

LLC resonant converter is widely used in big data centers and telecom rectifiers because of its ZVS, ZCS, and high efficiency. These applications require a high voltage step down LLC converter to convert high-voltage input such as 380Vdc to low-voltage output such as 12Vdc. However, with the traditional resonant transformer structure of LLC converter, because of the high voltage step down, even if the secondary windings' turn number is designed only 1, the primary winding's turn number will be a