A novel ZVS push-pull type LLC series resonant Dc-Dc converter for hybrid fuel cell power systems

Fuel cells are becoming a more attractive option for many remote power applications. To effectively control fuel cell system energy flow, improve system efficiency and lengthen lifetime of the fuel cell itself, a novel push-pull type LLC series resonant dc-dc converter was proposed. This converter, besides possessing all advantages of conventional LLC converters, emerges as a higher efficiency can be achieved for the merit of primary resonant current can be halved and where each half is carried by one push-pull branch, while the high voltage issue for conventional push-pull converters being overcome without employing the series-switches technique, and which turns out to be favorable for improving overall efficiency as well. Additionally, the wide input range capability further endows the proposed converter the applicability for the fuel cell output characteristics. Therefore the proposed converter is very suitable for the hybrid fuel cell power systems. The detail operation principles and converterpsilas characteristics were presented and the validity and applicability were also verified by a 1 kW prototype.