LLC Resonant Converter with Reconfigurable Voltage Rectifier for Wide Input Voltage Applications

In conventional LLC converters, when the input or output voltage is wide, the switching frequency must have a wide-swing range to achieve the desired output or input voltage that results in decreased efficiency. In this paper, a novel LLC converter with a reconfigurable rectifier is proposed to achieve high efficiency with a narrow switching frequency range. The proposed converter is suitable for applications that call wide input and wide output voltage ranges. This converter integrates three rectifier structures: a voltage-doubler rectifier (VDR), a voltage-tripler rectifier (VTR), and a voltage fifthfolder rectifier (VFR), all integrated into a novel rectifier structure that switches between them depending on the input voltage values. As a result, the switching frequency range becomes narrow with improved efficiency. This paper will show that Zero-voltage-switching (ZVS) is realized in all power MOSFETs, and zero-current-switching (ZCS) is achieved in all power diodes. A 250 W converter prototype was built and tested to verify the feasibility of the proposed converter.