High-Conversion-Ratio Push-Pull Resonant Converter for High-Power Fuel-Cell Applications

Abstract

We propose a high-conversion-ratio push-pull resonant dc/dc converter for high-power fuel-cell applications. The conventional converter suffers from a high current spike at the secondary-side switches when the load exceeds the threshold. The proposed converter incorporates a resonant neutral-point-clamped (NPC) cell on the secondary side, and therefore does not have the high current spike, but maintains the advantages of the conventional converter such as high step-up function, soft switching capability. When the load is over the threshold, the switches of the NPC cell are turned off with complete zero-voltage-switching (ZVS) and its diodes are turned off with zero-current-switching (ZCS). The theoretical analysis of the proposed converter is presented, then validated using a 1.2 kW laboratory-built prototype. © 2023 The Korean Institute of Power Electronics.