A new hybrid mode control strategy of flyback inverter for photovoltaic AC modules

According to the topology of flyback for photovoltaic grid-connected inverter, a new switching strategy was proposed to make the flyback inverter working in hybrid operation modes. To make the corresponding boundary curve between Discontinuous Conduction Mode (DCM) and Continuous Work Mode (CCM), a suitable transformer is selected, which can overlap the inverter primary side input current curve, especially can makes the flyback inverter works at alternate mode, DCM, boundary work mode (BCM) and CCM within a half sine wave. By the help of analyzing the principle of the new control strategy, the relationship between the reference signal (including the duty radio, D and the peak value of the primary side current, I_pt) and the grid current was derived, and with Matlab simulation software, the feasibility of the proposed hybrid operation modes was verified. The proposed switching strategy can make the output current of ACM in pace with the grid voltage, and the power factor is nearly 1.0.