DC to Single-phase AC Voltage Source Inverter with Power Decoupling Circuit based on Flying Capacitor Topology for PV System

A novel power decoupling circuit using a flying capacitor topology is proposed in this paper. The inverters, which are connected to a single-phase grid, have single-phase power fluctuation at the twice the grid frequency. Thus, bulky electrolytic capacitor is generally used as DC link capacitor. In the proposed circuit, the power fluctuation is compensated by the flying capacitor in the flying capacitor DC-DC converter. The proposed circuit does not need an additional magnetic component in comparison with the conventional system, which has a boost chopper and an inverter. The proposed converter is experimentally tested with a 1-kW prototype. A voltage ripple at twice the frequency on the inverter DC voltage is suppressed from 35.1% to 4.6%. Moreover, the maximum efficiency of 94.5% with an output power of 1.0 kW is achieved. Finally, the design method of the boost-up inductor for proposed circuit is estimated by experiment. As a result, the error of the ripple current between design and measurement value is 4.7%.