Modulation Scheme for Dual Active Bidirectional Flyback Converter

This paper proposes a novel modulation strategy for a bidirectional flyback converter. The salient feature of this modulation strategy is simultaneous conduction of switches located on either side of the transformer for some period of time for obtaining lower output voltage without going for lower duty cycles. For power flow from Port-1 to port-2, port-1 side switch is operated at a higher duty cycle than the port-2 switch. Similarly, for power flow from Port-2 to Port-1, Port-2 side switch is operated at a higher duty cycle than the Port- 1 side switch. This strategy will make higher frequency operation feasible as very low duty cycles are avoided. With this modulation scheme a certain output voltage can be obtained by a number of combinations of the two duty cycles of port 1 side switch and port 2 side switch. This has been established by extensive simulations presented in this paper. Further, steady state input- out relations have been analytically obtained. Extensive simulations were conducted on this circuit using MATLAB, and the results align well with the relationships derived analytically. This modulation scheme effectively converts a conventional bidirectional flyback converter into a dual-active bidirectional flyback converter.