Design Methodology of Bidirectional Flyback Converter for Differential Power Processing Modules in PV Applications

A bidirectional flyback converter is a suitable topology for a PV-to-bus differential power processing (DPP) module in PV applications because of its electrical isolation capability, bidirectional power transfer, high step-up ratio, and simple circuit structure. Bidirectional flyback converters differ from the conventional flyback converters, which has power switches and snubber circuits on both the primary and secondary sides for bi-directional operations. The poor reverse recovery characteristics of the anti-parallel diode of the secondary (output) side power switch increase the switching loss and reduce the reliability. This paper proposes the design methodology of the bidirectional flyback converter for operating under the boundary conduction mode (BCM), which can show low power loss from the reverse recovery issue. The suitable magnetizing inductance is obtained by calculating the power losses in the bidirectional operation at the rated load. The validity of the proposed design methodology is verified using a 25.6-W bidirectional flyback converter prototype.