Novel Resonant Bidirectional DC–DC Converter Based on Asymmetrical Half-Bridge Flyback

This article proposes the novel use of the asymmetrical half-bridge flyback (AHBF) topology with a bidirectional behavior. AHBF has seen an increase in industrial use in recent years due to its advantages over other topologies, such as its high power density, low component count and wide voltage range by exploiting the resonance between the transformer leakage inductance and an added resonant tank. Up to now, the AHFB topology has been used as a step-down converter; furthermore, by making use of its synchronous rectifier, a resonant flyback-forward topology with step-up function is obtained. The proposed isolated bidirectional converter can achieve high voltage conversion rate with elevated efficiency and power density. To test the theoretical analysis, a 240 W prototype with 320 to 400 V on the high voltage side and 12 to 24 V on the low voltage side built with GaN technology is carried out in the laboratory. A high boost and buck capability with wide voltage range is obtained, as well as reaching a maximum efficiency in step-down mode of 97.97% and of 97.76% in step-up configuration. This makes AHFB an attractive alternative for bidirectional conversion applications.