A Novel Single-phase Step-up Five-level Inverter Based on Model Predictive Control

To solve the problem of unbalanced capacitor voltage and low utilization rate of DC voltage in single-phase switched capacitor multilevel inverter, a novel single-phase step-up five-level inverter is proposed. The inverter is composed of a DC voltage source, switched capacitor unit and two half bridges, whose output voltage can reach twice the DC input voltage. The working principle, capacitor voltage and switching voltage stress of the inverter are analyzed. By controlling the on-off of the switches of the inverter, the capacitor can be charged in series and discharged in parallel with the DC power supply in a cycle, and the capacitor voltage self-balancing can be achieved without additional control. Model predictive control is adopted for grid-connected control of the inverter, which overcomes the adverse influence of modulation ratio changes on the inverter. The simulation and experimental results verify the effectiveness and feasibility of the new inverter and control method.