High Step-Up Zero-Voltage Switching Resonant Converter for Megahertz Applications

Due to the high efficiency benefited from soft switching technology, resonant converters are more suitable for high frequency applications than conventional hard-switching power converters. This paper presents a novel step-up resonant converter for megahertz applications. The converter features dead-time free zero voltage switching (ZVS) operation. Firstly, a symmetrical current-fed structure at the front side, which avoids the risk of input voltage source short circuit, thereby eliminating the necessity for dead-time, reducing control complexity and improving stability. Meanwhile, a unique parallel-loaded resonant unit enables the fully utilization of the output parasitic capacitance of the switches to achieve ZVS, nearly eradicating switching losses and enhancing efficiency. A mathematical model derived from the analysis of the converter demonstrates its high step-up capability. To verify above features and feasibility, a 2MHz/600W SiC-based prototype is developed and evaluated through both simulation and experiment, achieving a peak efficiency exceeding 97%.