Hybrid Converter with Multiple Sources for Lithium Battery Charger Applications

This paper proposes a hybrid converter with multiple sources for lithium battery charger applications. Since the output voltage of a lithium battery charger is very low, its charger needs a higher step-down voltage for a utility line source or a step-down voltage for PV arrays. In order to implement the battery charger with utility line and PV arrays sources to simultaneously supply power to battery, a flyback converter is selected for utility line sources, and a buck converter is adopted for PV arrays source. Due to leakage inductor of transformer in flyback converter, an active clamp circuit is introduced into flyback converter to recover the energy stored in leakage inductor. In addition, flyback and buck converters can adopt switch integration techniques to simplify circuit structure. With this approach, the proposed hybrid converter has less components, is lighter weight and has smaller size and higher conversion efficiency. Finally, a prototype of the proposed hybrid converter with output voltage of 5 V~8.4 V and output maximum current of 12 A has been implement to verify its feasibility. It is suitable for the lithium battery charger applications.