High Efficiency Grid Tied Interleaved Flyback Micro Inverter with Hybrid Mode for Pv Ac Modules

Boundary Conduction Mode (BCM) and Discontinuous Conduction Mode (DCM) control strategies are widely used for the flyback micro inverter. For the interleaved flyback micro inverter, the dominant losses with heavy load include the conduction loss of the power MOSFETs and diodes and the loss of the transformer while the dominant losses with light load include the gate driving loss, the turn off loss of the power MOSFETs and the transformer core loss. Based on the loss analysis, a new hybrid control strategy combining the two-phase DCM and one-phase DCM control is proposed to improve the efficiency in wide load range by reducing the dominant losses depending on the load current. The proposed control strategy consists of two components: the proportional-resonant (PR) controller with the harmonic compensator (HC) and the hybrid nominal duty ratio. Moreover, by applying the hybrid nominal duty ratio yielded from the proposed operation mode selection, the disturbance rejection is achieved more effectively, and the control burden is reduced. Finally, the simulation results were shown to verify the tracking speed and disturbance rejection performances of the proposed control strategy.