A Wide Input Voltage Range LLC Converter with Multi-mode Operations

In this paper, a novel LLC resonant converter with multi-mode operation rectifiers is proposed to regulate the wide low voltage range photovoltaic panel and to connect the panel to the high voltage DC bus. The proposed converter can operate in three modes of operation: as a voltage-doubler rectifier (VDR), as a voltage-tripler rectifier (VTR), and as a voltage fifthfolder rectifier (VFR). Therefore, the proposed converter covers a wide voltage range by automatically changing the rectifier structure. The three operation modes keep the switching frequency range close to the resonant frequency resulting in increased performance efficiency. The benefits of this topology include improved efficiency and a narrow switching frequency range. Moreover, zero-voltage-switching (ZVS) and zero-current-switching (ZCS) are achieved in all power MOSFETs and power diodes. A 250 W LLC resonant converter for wide input voltage was designed and simulated to verify the theoretical analysis and the circuit functionality.