Power Balance Strategy for Staircase Waveform Synthesis of the Cascaded Multilevel Inverter

Firstly, it points out that the III-type cascaded multilevel (ML) inverter is the best topology, when outputs the same quality voltage. Secondly, the swapping pulse power balance strategy is proved to be better for the I-type cascaded ML inverter if the number of cascaded cells is lower than seven, or adjusting firing angles is better. After detailed analysis, it points out that the II-type can realize power balance by adjusting firing angles in one output cycle, whereas the III-type cascaded multilevel inverter can not ensure power balance. Since the switching mode is redundant for the II-type, it has several kinds of power balance equations. Finally, a one phase 2 kVA prototype is designed to verify the validity of the power balance strategy for II-type.