A high step-up ratio resonant converter for high-power applications

With the rapid development of large scale renewable energy sources and HVDC grid, it is a promising option to connect the renewable energy sources to the HVDC grid with pure DC system, in which high-power high-voltage step-up DC-DC converters are the key equipment to transmit the electrical energy. This paper proposes a resonant converter which is suitable for grid-connected renewable energy sources. The converter can achieve high voltage-gain using LC parallel resonant tank. It is characterized by zero-voltage-switching (ZVS) turn-on and nearly ZVS turn-off of main switches as well as zero-current-switching (ZCS) turn-off of rectifier diodes, moreover, the equivalent voltage stress of the semiconductor devices is lower than other resonant step-up converters. The operation principle of the converter and its resonant parameter selection is presented in the paper. The operation principle of the proposed converter has been successfully verified by experiment results.