An architecture of multiple-integrated converter modules sharing an unfolding full-bridge inverter with a pseudo DC-link (MIP) is proposed for grid-connected photovoltaic (PV) systems in this paper. The proposed configuration can improve the power conversion, the control circuit complexity and the cost competitiveness. The proposed MIP is composed of distributed flyback dc-dc converters (DFC) and an unfolding full bridge inverter with an ac filter. The DFCs can eliminate the shading effect by using the individual maximum power point tracking (MPPT). In conventional flyback-type single-phase utility interactive inverter, discontinuous conduction mode (DCM) and boundary conduction mode (BCM) are popular because of the inherent constant current-source characteristics more desirable for grid-connection and of the simple procedures for the controller design. However, the operating mode suffers from a large current stress of the circuit components, which leads to the low power efficiency. To avoid this, the DFCs operates under Continuous Conduction Mode (CCM) that allows reduced current stresses and increased power efficiency, as well as the low material cost. The current control loop of the converters employ primary-side regulation contributing to improvement of dynamics as well as the cost reduction significantly due to the elimination of high linearity photo-coupler device. Development of a new DC current loop that maintains the level of DC current injection into the grid within the levels stipulated by IEEE 1547 will be dealt as well. The performance validation of the proposed design is confirmed by experimental results of a 200W hardware prototype.
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