Power pulsation decoupling for a two-stage single-phase photovoltaic inverter with film capacitor

This paper presents a power pulsation decoupling strategy for a two-stage single-phase photovoltaic (PV) inverter with film capacitor, which has small capacitance and large voltage ripple. Such large voltage ripple at DC bus is propagated to the PV array and decreases the maximum power point tracking (MPPT) efficiency. To maintain the MPPT efficiency, a new small-signal model which considers the DC bus voltage ripple is derived. Based on the model, a new boost current controller is developed and it consists of two parts: a PI controller to control DC component and a repetitive controller to suppress the harmonic component caused by the DC bus voltage ripple. Simulation results show that the proposed controllers have drastically reduced the double frequency voltage of the PV array, which improves the MPPT efficiency of the PV array. Experimental result further verified the effectiveness of the controller, the measured MPPT efficiency was increased from 97.06% to 99.9%.

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