New five-level inverter-based grid-connected power conversion interface

In this study, a five-level inverter-based grid-connected power conversion interface is proposed. The output current of grid-connected power conversion interface is controlled to be sinusoidal and in phase with the utility voltage so as to perform the unity power factor. The grid-connected power conversion interface is configured by a DC-DC boost converter and a proposed five-level inverter. The DC-DC boost converter is employed to boost a lower DC voltage source. The presented five-level inverter is composed of a series/parallel capacitor set and a full-bridge converter. The presented five-level inverter contains only five power electronic switches, thus simplifying the circuit configuration. In addition, only one power electronic switch is switched in high frequency and only three semiconductor devices are conducting in series at the same time in the presented five-level inverter. Thus, the power loss will be reduced and the power efficiency will be improved. Moreover, the control for balancing the voltages of DC capacitors of the presented five-level inverter is simplified because the DC capacitors are discharged in series and in parallel alternately. A prototype is developed and tested to verify the performance of the proposed grid-connected power conversion interface. The experimental results show that the proposed grid-connected power conversion interface achieves the expected performance.