New cascaded multilevel inverter by using capacitor based basic units with the capability of charge balance control method

Abstract

In this paper, a new basic unit for cascaded multilevel inverter is proposed. In the proposed unit, a capacitor is used as a voltage source. Then, according to the location of the capacitors in basic units, two cascaded multilevel inverters are proposed. The main advantage of the proposed topologies is decreasing the number of required insulated dc voltage sources. For the proposed cascaded inverter, three algorithms to determine the magnitude of dc voltage sources are proposed. Moreover, in order to balance the capacitor voltages a new control method is proposed. Finally, the correct performance of the proposed cascaded inverter is reconfirmed through simulation results on a five-level proposed inverter in EMTDC/PSCAD software program.