Hybrid Interleaving Control Strategy for Interleaved Flyback Microinverter

The flyback converter is widely adopted due to its simple structure and compact form factor. An interleaved flyback converter can further enhance power capability. To increase energy transmission density, the system typically operates in Boundary Conduction Mode (BCM). However, this mode often leads to incomplete interleaving of the primary transformer current near power peaks due to an excessive duty cycle. To address this issue, this study introduces a control method that incorporates a constant primary peak current in a variable frequency discontinuous conduction mode (VF-DCM). This strategy can limit the maximum duty cycle by setting a constant value for the primary peak current, thereby ensuring complete interleaving of the total input and output currents near the power peaks. Considering the high voltages and currents that the switching devices endure near the power peaks, a resonant period compensation is adopted to enable zero-voltage switching (ZVS). The proposed method is substantiated through detailed simulations conducted using PLECS software, which confirm that the approach can achieve complete interleaving across the entire operational range, reduce the ripple in total input and output currents and lower the harmonic content in the grid current.